The Charge Of The Turbo Brigade:<br/>A Century And More Of Boost
We’ve got it in for air

The internal combustion engine seemed to be doing fine on its own in the 1970s. After all, its dense fuel and explosive nature was pumping out previously unthought of levels of power. We’re talking about something that was measured against the previous standard method of transport, the muscle and sinew of a horse, and power levels were already being reached that were the equivalent of dozens of squadrons of flesh and bone. But still people wanted more. And there was an atmospheric technology on the cusp of being perfected that could take things stratospheric, if only the challenges could be surmounted: turbocharging.


The 1970s saw turbocharging break out into the mainstream. Horsepower numbers went vertical: hundreds became a thousand and more. The age of the turbo had arrived, and ever since then, if you’ve had a street car with a Turbo badge on the back you know you’d made it.


It could almost make you pity the air. It’s not like air wasn’t already having a hard time of it: sucked in, soaked in fuel and then blown up. Turbos added to the torture: what remained would now be compressed, spun and injected back into the engine to reach new levels of fantasy power numbers.

The story of boost has ebbed and flowed, varying in application and moving between the benefits of economy and the stuff we’re more interested in: raw power. All tuned engines have a mystique about them, whether a grunty V8 or howling V12, but the additional whistle and whine, pops and bangs of a turbocharged engine are quite magical. The sound is one thing, but it’s really what your backside feels when driving a boost-laden car that makes the difference.

Chopard Superfast event to launch the new range of super fast watches at the Ascari Race Resort, Spain, 22 November 2012

So it’s a relatively modern invention then? Of course not. As is so often the way with the automobile, boost’s roots (if you’ll excuse the pun) go right back to the dawn of the motor car. Remember that in the beginning – as in, the turn of the 19th century – there simply wasn’t a single method of motivation that had been settled on. It was the age of discovery. Internal combustion (and its various ancillary hop-ups) was just one of a number of dangerous-seeming options: steam, electricity, gas and more were other avenues of investigation. Proof, as ever, that nothing under the sun is new.

The 2013 Autosport International Racing Car Show

Turbo’s exhaust-driven methodology had split off from its original line of development, the mechanically driven supercharger, and therefore its original epithet was turbosupercharging – proving that anything with ‘super’ in the title always sounds good.


Almost predictably it’s our old friends Gottlieb Daimler and Rudolf Diesel who pioneered the concept of turbocharging right back in 1885, by using pre-compressed air to increase power and reduce fuel usage. 1885! A Swiss engineer, Dr Alfred Büchi, then refined the process, finding 40 percent power increases during testing. He pushed through commercial patents in 1905, but the technology only stuttered along before finding an appropriate environment in which to gestate: a world war.


From the beginning, turbos were associated with diesel engines, but this period also saw turbocharging’s primary use diverging from its origin: it seemed that everything but cars would be avenues for turbocharger experimentation for almost the next half century. The French used turbos to increase the power of their WW1 fighter plane engines, and then as the conflict drew to a close the Americans applied a turbo to their V12 Liberty aero engine.

The interesting factoid here is that the engine was tested at Pikes Peak in Colorado, where it could be proven to compensate for the loss of power that engines would experience in high altitude, low air pressure environments.


Ships and trains also saw turbos added to their vast internals in the 1920s to produce serial units producing some tens of thousands of horsepower, and then some of the most iconic fighting machines of the 20th century were amped up in the same way: the B17 Flying Fortress and P47 Thunderbolt amongst many US planes, and the Focke Wulf FW190 on the German side.


Without wishing to go off on a tangent about classic fighter planes (much as I’d like to, I have to admit), this period also demonstrates one of the biggest differences between turbo- and supercharging – just where the power is created – as both methods were heavily exploited in period.

Supercharging (such as used on the engine of the P51 Mustang) directly affects the internals of the base engine: mechanically connected to the engine’s crank it soaks up horsepower to run, and then throws a multiple of that back at the engine to cope with. The power is also more predictable and controllable, but doesn’t have the same level of power hike that turbocharging can potentially provide.


Then we get onto lag: along with materials, the main reason why turbocharging hadn’t really made it into the automotive industry so far. From their use on planes and ships, turbos were mainly seen as ways of overcoming the inertia of massive engines or balancing power loss due to extraneous conditions.

Rapid changes in power delivery were not really possible, plus the idle speed of an average car at the time just wouldn’t provide enough exhaust gas to keep the fan spinning effectively. It’s why supercharging had remained the predominant boost technology in the automotive world throughout the inter-war period, with cars like the epic supercharged Blower Bentley powering to multiple successes in the early 1930s.

Gatebil on ice

Because turbocharging acts on the exhaust gases it could be more powerful and more efficient, recycling spent energy from the core engine. Aside from lag, the other problem through this period was the difficulty of preventing the components detonating under load…

But the exponential rate of development caused by two world wars overcame many of the issues: improvements in metallurgy and other sciences would permeate down to the previously frivolous automotive industry. It would still take time though. In the immediate post-war era, the only automotive outlets for turbos were still in the commercial arena, for example, trucks and industrial vehicles.

From interstates to racetracks

Caterpillar can be credited as one of the firms that helped bring turbos to the mainstream. Power-hungry machinery required a constant quest for horsepower, and a collaboration with Garrett (who had made intercoolers for planes like the B17 and the turbine for the P80 Shooting Star jet) showed that turbocharging diesel engines was a viable – and indeed optimal – way forward. Improved metals and alloys radically changed what was possible: now the housings, seals, turbines and compressors could be made much smaller and stronger – they actually had a chance of surviving the pressures created.

The big T15 commercial turbocharger of 1955 took Garrett down a path that would lead to their involvement with one of the world’s first turbocharged production cars, the Oldsmobile Jetfire Rocket of 1962.


Who wouldn’t want to own a car with than name? All it needed was Super in there somewhere. Unfortunately that was the best thing about it: the turbo on its V8 had a hilarious compression ratio of 10.25:1, it suffered from severe knocking and enormous lag. Not helping things was the single side-draft carburettor’s unpredictable fuel delivery and the overly complex water/alcohol mix injection system.


The latter was the Turbo Rocket Fluid: a marketing man’s dream and driver’s nightmare. Most people didn’t drive the car hard enough to generate the necessary boost, resulting in a lack of lubrication for the turbo’s compressor shaft and frequent jamming…


Chevrolet’s Corvair Monza of the same year was a little better, with a simpler and more effective turbocharger, but it wasn’t enough to ignite the passion of the masses.


Continued reliability (both perceived and real) and the relative commercial failure of these early cars meant that turbos lapsed back into the hinterland for almost a decade. As with so many strands of automotive history, it would be the 1970s that would have the biggest impact on turbocharging.


By now the keys to a turbo car weren’t high on people’s lists. Perhaps this advert shows someone trying to swap their Monza for a potted plant… The 1973 oil crisis put a premium on gas prices globally, and even in the previously profligate US an awareness of what could happen at home caused attitudes to change. First, commercial use of turbo-diesels rocketed, with the cost saving of fuel finally offsetting the high development costs being incurred.


But even if you couldn’t find turbos in mainstream street cars during this time, there were still two arenas where turbos were being taken up: specifically hot rodding and racing. Turbines and turbochargers made their way into USAC racing in the mid-’60s (although a diesel-turbo had been entered into the Indianapolis 500 as far back as ’52, and in Europe a Rover-BRM gas turbine also raced at Le Mans in ’65).


A Garrett/AiResearch-enabled Offenshauser Eagle won the 1968 Indy 500, hot on the heels of the famous STP-Paxton turbine car performing strongly the year before. It’s said that some of these early Indy cars had up to three seconds of lag before the power kicked in! So things were still far from ideal.

Gatebil on ice

Something that changed the hot rodding landscape in the US was the TurboSonic range of retrofit turbo kits: I loved this refrain from a book on turbos, that this put ‘thousands of turbochargers into the hands of energetic consumers who knew nothing at all about what turbos were, how they worked, or how to install them.’ But install them they did. So, returning to the ’70s, and all these strands came together: a changing environment, the development of automotive turbos as a viable, reliable technology, their taming by motorsport and adoption by the tuning hardcore. The floodgates (wastegates?) were now open for wider adoption.


The focus now changed to Europe: initially a Europe looking back at America (and an American sorting things out). In a story which continually ticks so many boxes of things I love, this gives me the excuse to mention Can-Am. This is where turbocharging was unconcerned with efficiency and instead unleashed in the search for pure, unadulterated, volcanic power.


Porsche’s developments of the Le Mans-winning 917, the fearsome 917/10K and /30K, pulverised the CanAm series in 1972 and ’73. The former produced 900hp, the latter anything up to 1,600hp – levels of power that previously couldn’t be dreamed of and are rarely achieved now. Not that it was initially very useable. We can still complain about lag on modern cars, but it’s nothing – absolutely a different world – to the first iterations of Porsche’s brutal turbo racer.

This was no bespoke unit, remember, but a development of Porsche’s 350hp eight-cylinder of the decade before; the incremental increases in power expected of the engine were revealing flaw after flaw. Low speed performance was terrible, throttle response ambiguous and the idle poor. But people were learning, and learning fast.


It was the engineering know-how of Mark Donohue and the Penske team that turned things round, making alterations to the induction and fuel delivery along with geometry and aero changes that created a legend. The 917/30 has to go down as one of the most awesome turbo cars ever produced, weighing just 816kg, with its 5.4-litre flat 12 and mighty twin-turbochargers. Porsche would of course figure strongly again in the turbo story, but there was a brief interlude from one of its fiercest rivals – and an important one in terms of bragging rights.

Turbos tearing up the streets

It’s actually BMW that can take credit for introducing Europe’s first turbocharged production car. Their range-topping 2002 Turbo was unveiled at the 1973 Frankfurt Motor Show: a KKK turbo running at 6.9:1 compression was added to the Neue Klasse’s two-litre inline four, to produce 170hp and a commensurate amount of torque.


Light boost was used to minimise pre-ignition of the fuel in the cylinders and prevent knocking, and the 0-60mph was a supercar-style sub seven seconds – though lag was still a major factor. The picture above isn’t a driver being exuberant, it’s just what driving a 2002 Turbo was like.


A bigger problem was that BMW were just the wrong side of the oil crisis: just 1,672 were built before production ceased. And that lag? Maybe that’s why there are thought to be less than 500 Turbos still in one piece.


At the same ’73 Frankfurt show as the 2002 Turbo, Porsche’s stand also featured a turbocharged 911 concept: a 2.7-litre quoted as having 280hp and a top speed of over 160mph. This was the precursor to the legendary 911 Turbo. A pre-production model was shown off in ’74 before an all-out turbo attack on the streets of the world the following year. The Turbo had arrived.


A larger three-litre engine to balance off-boost inertia, and that whale-tail body became shorthand for performance.


It set the template for turbo-powered sports cars from then on, a high-performance GT with relentless, overwhelming power, and it’s certainly something that defined a new benchmark for Porsche themselves.


From there, both BMW and Porsche pursued turbocharging in racing as part of an all-out arms race: the former’s 320 range topped out with the over-the-top Turbo models, whilst Porsche ramped up through iterations of the 935 to make monsters like the Moby Dick.

The 41st AvD Oldtimer Grand Prix, run 9-11 August 2013 at the Nürburgring circuit in Germany

Tuners on both sides of the Atlantic were getting on board with turbos in a big way too, with Kremer and more taking turbo-charged Porsches to even greater levels of beautiful, flaming power. Boost was now hitting the headlines on both the street and track: it was the beginning of something big. Poor old air. It’s had a hard time since then, and I’ll be taking a look at some key turbo cars from the more recent decades in a following story tomorrow. In the meantime, there’s a whole world of boost to be discovered, so welcome to the Speedhunters #WeHaveBoost theme.



Comments are closed.


by Oldest
by Best by Newest by Oldest

Interesting article for sure, but... You forgot about the SAAB 99 Turbo!! If I'm not mistaken, it was the first production car to really control the lag and improve the reliability of the engine and turbo thanks to the blow off valve the engineers at SAAB made.


Bumblebi I agree, it was defiantly a groundbreaking car for sure. Ive ridden in a few SAAB turbos, and their quite fun.


Thank you for feeding my brain with some much valued auto history.


Bumblebi Only real noteworthy fact of the 99 Turbo is that it was the first "mainstream" or "family" car that had a turbo. The first turbo car for the average chap. Never heard about the swedish inventing the blow off valve or a recirculation valve..


dovvv Bumblebi As I said (or atleast meant to say) is that I was not sure about it, but I think they did invent the blow off valve/wastegate (dad is a SAAB freak so yeah..), but I know that the turbo in the 99 Turbo was a different kind that the ones in the 2002 Turbo and the Porsche 911 Turbo.  It was designed to work better on low RPMs than the other ones.

Patrick Deschenes

What about the Saabs?

First turbocharged WRC win is worth at least a mention, no?


Great piece, thank you.


Bumblebi We're not done yet! :)


Are superchargers welcome in the #wehaveboost theme or not?


TURBOS  so much lag then soooo much boost all building and building then pop pop bang next gear lag........ boost........ power red line pop pop bang .... equals smile from ear to ear. mk4 escort RS turbo my drug and I'm a completely addicted.


I'm sorry, how can you write a story on the history of turbos and cars without including Saab (99 Turbo, 900 Turbo APC, Trionic, etc etc etc) - the company that actually brought turbos to the masses in a usable form?
Also the first production car (at least in the us) with a turbocharger and a multi-valve head.


This is right. This is so true!
And the Bmw 2002 was not the first production car in europe with turbo charging.
Ford introduced the Ford Capri May Turbo BEFORE Bmw does. So the first production car with Turbo Charging in Europe was the Ford Capri May Turbo at 1970! It was a tuners car, such like a bmw / alpina.
But you could buy it new with full warranty. Around 10.000 was produced with May Turbo.
These cars had between 180HP (2,3litre) and 206HP (2,6 litre) with an weight of only 1000kg.
It was also the Ford Zakspeed Turbo Capri who clocks one of the best times on the nordschleife ever. with an awesome 1,4l Turbocharged engine.


maranello48 Do they provide boost?


The Porsche "Moby Dick" had much power, but they lost in some races against the turbocharged zakspeed capri with much less weight. This video is a MUST have seen for all turbo lovers:
there you see the Zakspeed Capri fighting against the moby dick. The red moby dick in front had awesome 1034hp and the 650kg capri around 580hp. The start is just awesome and the acceleration of the Moby Dick is brutal!


why is "10.25:1" "a hilarious compression ratio" with a turbo? high compression with boost is awesome!


Other the question above, I really liked this feature. I love boost. Turbos became my profession for a number of years, and I recently just swapped back over from my gigantic basketball sized Turbonetics Super T-76 to a gigantic supercharger. I always think about the turbocharged 1000hp monsters of the F1 era (Mcclaren MP4/4 in particular). But all in all, great feature.


Erik001 JamesMackintosh Wow, what a video! The acceleration on the Capri looks pretty insane but the Moby Dick 935... damn!
As for mention of the Saab, as I said below, we're not finished yet! ;)


This reads like the writer hasn't got a clue about turbos or turbocharging at all, and seems to be mixing up compression ratio with boost pressure, not to mention other things in this article.
A waste of some awesome pics.


Wildcardfox  Interesting - obviously most people put turbos on lower comp engines to avoid the risk of det/increase reliability. I'm sure the tech back then wasn't really sophisticated enough to avoid these issues! Would you run this sort of set-up on normal pump fuel then?


Wildcardfox  So basically, when you add boost it increases the effective compression ratio.
So, an engine that has 10.25:1 compression may be fine when it's n/a, but once you start compressing that air and shoving it in, you start to get knock.
This is why turbo engines have lower compression than their n/a counterparts. It enables more boost.
These days with indirect and now direct injection, compression can be much higher than before. That's why the ZN6 twins can run turbos on their stock compression of 12.5:1.
But back then, due to carburettors, it wasn't possible to combine compression like that and boost.


SuzyWallace Wildcardfox  Well it is not that interesting. It is the popular
trend in engine building nowadays. I do agree with you for the Jetfire with
carburetion, the technology at the time played a key role into why they had so
many problems.
The shop that I am affiliated with almost exclusively builds
high compression engines that are either equipped with turbo(s) or a
supercharger. My particular setup is 700rwhp on 10:1 motor (Ford Modular V8). I
can make that power with extremely low boost (8-12psi). The new setup will be
set at 12psi, but I’ll have my old wastegate and my electronic boost controller
still in the system so the boost may be less. Under the turbo setup we hit our
numbers at 9 psi. The torque was 608 ft/lbs at 8.8 psi.
My car runs 91 octane, but other customers in states with 93
octane and run up to 900-1000 on the street, and on higher octane up to 1600hp
for some of the race/street vehicles. The shops heavy hitters—our Pro Street,
Real street, and True street cars run between 1900-2500hp. The Pro Street car
is 13:1 compression at around 47 psi on its twin turbos which propel it to 6.05
in the quarter. This shop has been building high compression motors for over 20
years, and even at those high power levels the engines last. The pro street car
usually last an entire season without having to have its engine rebuilt.
The benefits are no lag and huge amounts of torque, as well
as engine responsiveness. For a street car, it is great because the car drives
on motor without any low power issues. Most people always say that low
compression cars suffer from lack of power down low until the boost hits. When
the boost comes on they transform into rocket ships. On a high compression car
there is no doctor jeckel, Mr. hyde experience. The motor is quick and
responsive without the aid of the turbo, and when the power adder kicks in at
3-4 grand it just takes you to happy land. Plus, since you are in boost only 5%
of the time it is good to still have a powerful responsive motor. High
compression also helps to quickly spool up a turbo. 
Making high compression motors work with boost has a lot to
do with the timing and having adequate injector sizing. The key is finding the
exact moment of igniting the spark. The latter was researched by Mazda
extensively and culminated in their new engine lines that are running insane
compression ratio on (I believe it is) 87 regular octane. I think that it is the
old way of thinking that a power adder must be accompanied by low compression.
There are tons of benefits for high compression and boost, and lots of examples
of it being done properly now days.


Such a good read! Thanks Jonathan. It's amazing that turbos are so fascinating even when you look all the way back to the first ones being engineered. Then to see how far things have come. One car comes to mind, WEC Audi R18!


aussieANON Wildcardfox Well Thank you for
the response aussieAnon. I’m a little confused because your response states two
things that seem contradictory and I’m a little lost. It first states that high
compression+boost=knock, which I disagree with. But then it states that with
fuel injection setups you can manage it, which I agree with. So I’m confused as
to whether the former was responding that with the carburetors on the Jetfire
it could’ve resulted in knock issues? In any way I guess my response to Suzy
says my thoughts on high compression and boost setups.
As for turbos and my
background with them, I spent a number of years as a turbocharger and
intercooler specialist for a few companies. My focus was on designing and
building turbo and intercooler systems for vehicle applications. During that
time I was a Presicion Turbo and Engine distributor. I love boost, I don’t
really care how it comes by whether it be turbo or supercharger, its all good.


Wildcardfox  aussieANON Basically, yeah. I should've said that on a carbed engine, high comp + boost means knock unless you're on a fuel like E85, methanol, or some other form of very high octane.


Good article Jonathon. And one where everyone will respond with "what about (insert favorite marque here)". :-)
I am currently on something that has 6x 18 litre V32 turbocharged engines that produce in excess of 42000hp. Now that's boost!

p.s. I win. lol


SuzyWallace Erik001 JamesMackintosh 
Yes this is very nice to see. As I know he used at least more than 3.0 Bar boost in the capri but only for short time that he can overtake the moby dick at tight corners. I think the 935 is one of the greatest cars porsche ever made. Even if they are Old they are still very fast.


Wildcardfox  SuzyWallace : Couldn't agree with you more: It's al about propper fuel and ignition control. But it's also true that you can hop up low compression engines more then you can do high compression engines with boost. At least in theory. Low compression engines are more forgiving for error's....


Kevski Style Wildcardfox  SuzyWallace
You are absolutely right that a low compression engine with
boost is more forgiving which is the reason why factory compression ratios (cr)
are around 8:1 or 8.5:1. Carmakers do it because of insurance. For car
companies that sell cars with power adders from the factory, a low compression
ratio is a much safer option than a high compression car because: (1) there is much
more safety room from detonation on street octane due to a lower cr; and (2)
the companies know that people will crank up the boost from the factory
defaults and with a lower compression ratio it makes it a lot less likely that
they will destroy their engine, so it is better for the bottom line. But
cars like the new Cobra Jet are changing the idea that factory offered boosted
engines must have a lower cr engine. It comes with 9.5:1 compression ratio and
a power adder either a supercharger or twin turbos. Granted that is a drag
prepped car with zero factory liability outside of product design failures or
negligence, but it is still a instance where a car maker shook the norm of
having a lower cr engine accompanying a power adder and went with a little
higher cr engine instead. Mazda is also doing the same. Although, I still
suspect that lower cr will stay the norm in factory offered power adder
assisted engines.
By hop up do you mean you can add more boost? Or do you mean
that you can make more hp off of a lower cr boosted motor? On a given octane I
will agree that you can add more boost, but more boost does not equal more hp.
So I agree with you that on lets say pump gas (91 cali octane) if you were to run
beyond 12 psi on a high cr car you would be pushing it, but that 10:1 car will
make the same hp numbers—at a lower boost—than a comparable 8.5:1 car would on higher
boost (15-18 psi). Although the boost number of the lower cr car will be
higher, the higher cr car will hit the same power numbers and be equivalent. So
I guess I’m confused because I don’t know what “hop up” is referring to.
So just to recap: You are absolutely right that high
compression plus boost is less forgiving. It has be done completely correct,
from proper injector size, wastegate sizing, boost control, fuel pump sizing,
and tuning. If it is not correct 100% of the time, detonation will occur. But
on high hp cars we expect all of these things to be correct anyway, so I guess
those requirements are just the norm. But anyways, thanks for the comment.


Wildcardfox  SuzyWallace
This is right :)
In my opinion it is not bad to use high compression if you use low boost, good fuel and good throttle response to reduce turbo lag.
But if you reduce the compression you can get much more boost, even if the turbo lag will increase.
Best example is the VW (VAG) 1.8T 20V engine. It is very popular to reduce the compression to 7,5:1 or even 7:1 but than use boost pressure over 2Bar. Some of the fastest street legal VW drag racing cars (Golf and Polo) do 8 second runs in germany with this setup. Runs also with Ethanol, E85 is very popular!
Another funny thing is, to see what you can do today with old turbocharged systems.
For example I build this year one of the first turbocharged carburated Ford Ohc engines that can respond very well on throttle and rev into high rpm.
All I needed was an Wideband Lambda, Boost Controller, Boost related-Fuel-Regulator, ignition timing and exhaust Temperatur and a set up the carb to the boost. Tune a Carb to Turbo is like building a watch. not easy, very detailed, but possible.
Because it all relates mechanic and not electronic, I have no problems with throttle response and no electronic problems. It just works fine and there are no crazy problems because a wire is broken or you have a damaged air-mass sensor. Another thing is the Intake. Most tuners use a intake with 1 throttle body. and then 1 into 4. This is okay and best to get HIGH HP, but really you can get much better throttle response if you don't ignore the flow of air and use single throttle bodies.
In my car I use the Venturi effect so that the air speed will increase before the throttle bodies.
I use 2 throttle bodies on my car. The intake works such like this:
1 into 2 into 4.
- 1 Turbo
- 1 Intercooler
- 2 Throttle Bodies
- 2 into 4 Intake
- 40mm turbo outlet
- 50mm first pipe
- 65mm intercooler
- 65 to 50mm reducing out of the intercooler
- 50 to 65mm expand before the carb
So the air (even under boost) can expand into the intercooler and will be compressed if
the temperatures get colder. So you simply can use a smaller pipe out of the intercooler,
because the air is much colder and more compressed now. To increase the speed
and get better throttle response (and also reduce turbo lag) you use a little bit smaller pipe than before. and then let is expand again - lol ;-) sounds crazy but works fine. I tested this with some other piping (bigger piping, same diameter piping and so on)
One of the issues with turbo and carb is that the engine consump much more fuel and that
the car must run very rich at idle and very rich at full load and that the car must have a little higher idle rpm. Not the best way.
My own Turbocharged Capri Ohc runs at 8Psi boost ( for street use) and a compression ratio with 8,5:1 and producing 190hp with 95 octane fuel. The car can get 250-260Hp at 15Psi if I run 102 octane Fuel (Aral Ultimate 102) to reduce knocking.
you can get more information on my page about the car:
With that compression ratio - and if the ignition is set up right, you use a good head gasket, and with forged pistons, good piston oil cooling (I use a double piston oil cooling with 8 injectors that cool down the pistons from the sump) you can reach 350-400Hp and 25psi boost - out of a 2.0 litre engine with carb. funny thing.
A friend of me drives one of the high boosted carb engines I know for street use.
He use 29Psi Boost on his Carburated Turbo engine and use a  secondary methanol injection to cool down the engine under full load.
So in my opinion it is good to use a Compression Ratio between 8,5:1 and 9,2:1 for boost engines depending on the fuel and ignition timing. But this works very well for everyday driving.
If you made 1/4 Mile racer, you should reduce compression ratio to 7:1 and use more boost to get maximum peak Hp. And if you use high comp turbo engines, then you must be a professional tuner and be very careful in ignition timing. the engine can be damaged with wrong fuel.
But it works very fine and is also good for trackday use. you should see good results with high octane fuel or with ethanol on this high comp. engines. You should also use methanol to cool down the engine if exhaust temperatures get to high!


aussieANON Wildcardfox I'm sure that with the technology now days there are many
examples of carburetion high compression engines with boost that are running on
pump gas. I think that for the Jetfire, terms like "carburetion”, “turbo”,
“high compression” and “factory” say it all—these terms do not mix together
well to equal a great motor that will operate without issues. I’m sure that
nowadays properly done it is not a problem.


aussieANON Wildcardfox
And oh, that is not the true point. The point is not knocking by carbed engine. It is the temperatures and the material of pistons and the engine.
With Fuel injection you can cool pistons better and use higher boost. so BECAUSE OF THAT you can use more boost. It all depends on the temperature, ignition timing and fuel.
Also too high comp and too high boost means knocking!
It is just very simple - less comp, more boost
more comp, less boost.
if you can get same HP with more boost and less comp or with less boost and more comp. Both will be fine ;-)
But you have to keep in mind that with higher comp you can get better throttle response and normally you can get a bit higher HP with less comp and more boost!
So what we learn about that:
The main important things of tuning a turbo engine are:
- Fuel quality
- Fuel Injection and position of injectors [a carb is does the same, but the POSITION is different]
- Keep Temperature as low as possible (use bigger Intercooler!)
- Compression Ratio
- Boost
- Good Material that can withstand high temperatures
- Ignition Timing
- Exhaust Temperature (AVOID exhaust beckpressure and keep exhaust piping as large as possible)
Because they don't know or don't used intercoolers (FMIC) in the early years of turbo charged engines, the engine temperatures was very high and because of that the engines was very bad and last only for a short time.


Wildcardfox  Kevski Style SuzyWallace 
You are very intelligent, I like this Turbo Article of Speedhunters ;-)
I totally agree with you!


Erik001 aussieANON Wildcardfox  You know I didn't think about intercooling as a cause of the Jetfire's knocking. Good catch! Definitely, inlet temps are key and if it did not have an intercooler that would have added to the issues.


Wildcardfox  Kevski Style SuzyWallace :
Lower CR will stay the norm. But then again, these day's 9,5:1 compression ratio isn't all that high nowadays. So you could say thats probably the norm for low compression right now.
By hopping up I don't mean adding more boost. Boost in general is a weird term. I'd rather talk about volume. 14,7 psi or 1 bar in a car with a displacement of 1600cc isn't even remotely the same as with an engine of 5000cc. Looking at volume is way better to understand power figures. With hopping up I meant tuning a car for higher horsepower figures. The thing is though, that with low compression engines with equal cooling capabilities, the one with the lowest compression has the best thermal efficiency. But not by much. Factor in that it's almost allways down to the way components are chosen en the way it is tuned however, and that doesn't really make much of a difference.
BTW:The cali gas is that 91 octane NON or RON rated?


"Who wouldn’t want to own a car with than name?" <-error there. I do apologize, I just have a strong penchant for finding these.
I must say kudos on the tortured air bit, had quite a good internal giggle reading about that. 
I have been told that all facets of automotive technology has been explored at one point. Electric cars and charging stations were around 100 years ago as well.


Kevski Style Wildcardfox  SuzyWallace Thanks for the response. I do agree that 9.5:1 doesn’t
technically qualify as high compression, but it is higher than the standard of
8.4:1 that you will find in Fords GT500 or 8.2:1 that you will find in a STI.
You mentioned different cc motors in your example of how boost is different on
a smaller vs. larger motor, I’m not sure if you thought that my example of what
my vehicle makes at a certain boost level was some how relating my motor to a
smaller or dissimilar motor. The numbers I was stating were to be only judged
against the same motor with 8.5:1 compression ratio. I am unsure whether our California pump gas is MON or RON rated. All I know is that it is the worst gas in the country.
I disagree that a lower compression engine you will have
higher horsepower figures. The reason that I disagree is because it is all down
to cylinder pressure.
 Power is equivalent to cylinder pressure. If we can achieve
the cylinder pressure that we want dynamically with less strain on the motor
then why not do so? So lets say our target is 4000psi in the cylinder per unit
time. Higher boost or higher pressure (psi or bar—whichever you prefer) raises
the induction charge in temperature. So with low cylinder pressure (low
compression engine) you will need more boost to raise the cylinder pressure to
our target of 4000psi because we have further to go. The higher boost will
produce a higher intake charge temperature that you will try to remove after
the charged air leaves the compressor through intercooling means. Also the
higher pressure of the charged air will be denser so it is harder to feed it
into the engine (throttle body, intake manifold, etc.) because of increased air
restriction or drag. So with a higher density it takes longer to shove all of
those air molecules into the throttle body, and into the cylinders. With lower
cylinder pressure low in the rpm power band, we cannot offer a steady exhaust
pulse to the turbo low in the rpm band, so the turbo will not spool up until
the cylinder pressure becomes higher. Alternatively, on a higher compression
motor you start out with a higher cylinder pressure, so you do not need as much
boost to reach the target cylinder pressure of 4000psi. So with less boost the
charged air leaving the compressor is colder. Because it is colder we are not
relying the on intercooler as much to bring the temperature down before we
shove it into the engine.  Colder air is
less dense, so it will be easier to feed the air into the engine, passed the
throttle body and into the combustion chamber because the air molecules are not
packed so tightly. Another addition is that with an engine that has a higher
cylinder pressure down low in the power band we have a steady pulse that we can
use to spool up a turbo lower in the rpm range, so the turbo comes on quicker.
And once we have hit the target goal of 4000 psi cylinder pressure we will have
done it with less boost, so a higher compression engine is more boost
efficient. So, the benefits are: (1) you are closer to your target goal of
cylinder pressure; (2) less boost=colder air entering the combustion engine;
(3) colder air is less dense air, so we are having less restriction flowing the
air into the engine; (4) higher compression is more boost efficient; and (5)
because the motor has higher cylinder pressure down low in the power band, you
are able to give a steady pulse to the turbo, so the turbo comes on earlier.  
Here’s some vids from my team. I show these to illustrate
that these are motors that are doing more power than equivalent motors on low
compression ratio. Also we seem to be having a nice discussion of engines so
here’s some vids.  
Here’s one of our supercharged motors running around 13:1
compression doing 1600hp
 And our 6.05s ¼ mile pro street car that runs 13:1 on a
283cu in motor. This car was the fastest modular motor in the world for more
than a decade. I hear we were just edged out by our sister team by a tenth of a
second. But it is the fastest small motor car in the world. Stock cube is 281,
so it’s a tiny motor.
Other motors that my team has built that were the Heffner
Ford GT that held the standing mile record,
 and the Hennessey Ford GT that I think took the official
standing mile time.
 All motors are Accufab Racing High compression boosted engines.


Wildcardfox  Kevski Style SuzyWallace :
No no, it's not like that. I was referring to different boost levels, because, although this is a sort of conversation between us two, there are still a lot of people reading that are not in the know of things. I'm allways trying to educate I guess? Comes with job as being an engineer and writer I suppose? The reason I asked is because I live on the other side of the Atlantic (the pond for short), and allways see people complaining about it. I know the current highest octane rating in my country is 97RON (although in reality it's closer to 100RON). But, I the fuels you use are MON rated, that would compare to 91MON. 
I can understand why you dissagree, but let me tell you this: A cilinder is all about volume. Thats the only reall thing to make horsepower. About 2CFM makes 1HP. Pressure is more volume in the same space by compressing it, making it denser and in the process produces energy, which in this case is heat. Your absolutely right about the rest though. And especially on the street high compression turbocharging is the best way to go. You don't get the drawbacks that you mentioned above. But for absolute power, lower compression is still the way to go, as the thermal efficiency is better. Drag/resistance is counter balanced by bigger ports, since drivability is not an issue voor all out power.  But there is a question that come to mind: Why would you have all out horsepower if it's a bitch to drive on the street? The only reall answer should be: Because it's only used on the track. Ohterwise the old saying still goes:
Tuning should be a compromise between what is possible and what is necessary


Kevski Style Wildcardfox  SuzyWallace For what makes power, we are not talking about filling the
motor. And cfm to hp is based on brake specific, so it is dynamic. I don’t
recall ever saying that “x” hp is “a bitch” on the street. My car is
controllable at 700rwhp. I know that one of our 1300hp Ford GT’s is driving
back and forth to Vegas all the time—no issues. The 1600hp engine went into a
GT500. The guy races, but he also drives the car around in Arizona. Do we need
all this hp? That’s debatable, but is it practical? Obviously not. If all we
need is a car to get us from point A to point B, then we could use a 87 hp
Smart car to do the job. One could argue that would be the most practical
method. But in car culture and as car enthusiast we live in impracticality.
It’s about pushing limits. It’s about having more. There are lots of people
running big power numbers on the street. Some track their car as well as drive
them, but many don’t. Many just want a fire breather. Practical? I’ll leave
that up to them. This car culture is all about one word: passion.
 I come from an engineering, writing, and legal background.
The shop that I’m affiliated with builds engines for all types of vehicles and
setups (Street/Strip, standing mile, drag, land speed record, American lemans,
etc.) and the side that I am advocating for is based on that background. I’ve
never had the pleasure of visiting Europe, so I don’t know how your roads are,
but in California we are the land of freeways, and there are many places for a
person to use their power as an enthusiast. And California is not alone. People
in Florida, Texas and other states have locations where they can go and use all
of their power—whether illegally or legally. So having a person build or have
built a vehicle that is on the extreme of everything, I’m all for it. If it is
what they want, and if it fulfills their passion and their need for speed, then
I think it is all right. After all, this is what we love to do.  
 And yes this conversation is out in the open and available
to anyone who has internet. Whether this a teachable arena or moment? I don’t
know about that. What I do know is that we will continue to disagree about
which motor setup will make the most power. I guess we will just have to agree
to disagree.


Wildcardfox  Kevski Style SuzyWallace :
Don't get me wrong here: I won't say that either. What I will say, is to make absolute big power and forget about everything else, you will lose drivability. I'm talkig about horsepower figures in the 2000 Bhp and up.
As for the roads: Depends on the country your in. I've been to the States and Canada (relatives over there), but in general the roads are better maintained on this side of pond. Drag strips are a different matter though. Although we do have a lot of circuits with history.
As for the agree/disagree thing: I suppose you right. There are allways more ways to skin a cat I suppose? What I can agree upon is that for street use, high compression turbo charging is the way to go, so long as it's done right....


Amazing video. Just gotta say that the Porsche in the video is a 935K3, not a Moby Dick. Still an awesome car though.

Unverified User

I beg to differ when it comes to street automotive and or hot rodding cars, the NHRA, is home of thee fastest cars period, and they, use, superchargers.