I am having a dispute about turboing a high comp ratio application as appose to a low comp application. Yes lower means better psi levels and high means greater chance of "BOOM". what is more efficient high or low compression? this is a need to know kind of thing here not a Q on how I would turbo my car. MY BROTHER SEEMS TO Want TO KNOW HOW efficient THIS WOULD BE NOT HOW MUCH LOW COMP WOULD BETTER BENIFET THE TURBO AND ITS power output


sorry for the big letter but I will not fix that problem


http://www.cardomain.com/ride/2187947

Using a high compression ratio, medium boost level engine would ultimatley be more effcient in making power, IF you control and stop detonation.

Bob Norwood took a Ferrari F50, with an 11:1 compression ratio, and twin turbocharged it, around 15psi. He used a Motec standalone to control it all, high effciency water to air intercoolers and instead of gaslone, he used E80 as a fuel.

Also, look at the 80's Formula 1 cars that were turbocharged. They ran 1.8L high compression ratio engines, like 11-12:1 AND 30psi using methanol as a fuel. They made 800hp.....thats more the 400hp/liter!

If you think about it, the more avaiable cylinder pressure you have to turn the crank and create torque the more effcient an engine will be at making power. Theoretically, you would be able to use a larger turbo, which will be more effcient than a smaller one, and this will dealy spool time, which is normally bad but in this case, the high compression will keep the torque of the motor high until boost builds in the higher rpms and REALLY makes the torque.

Unless you have a bunch of money for RandD, then lowering the compression ratio, using a modest boost pressure (10-15psi) and makign sure the motor is well tuned is gonna be a lot cheaper, easier to tune and will give you some great power.

If I had some RandD money....I would be thinking about a 5-6L V12 a high, 12:1 compression ratio, 20psi of boost and either alky or possibly propane as a fuel. Just to experiment. But alas, I am not rich. Damn



1988 Pontiac Fiero, engine transplant underway.
2004 ECOtec, built and boosted

great right up. this explains it well


http://www.cardomain.com/ride/2187947

Hunter wrote:Bob Norwood took a Ferrari F50, with an 11:1 compression ratio, and twin turbocharged it, around 15psi. He used a Motec standalone to control it all, high effciency water to air intercoolers and instead of gaslone, he used E80 as a fuel.

If it is the same car that I am thinking of, the guy who owns the F50 was one of the creaters of the video game DOOM. I have actually seen the guy driving the car on the street a few times. And if you are ever able to go over to Bob Norwood's house, you will see some crazy ass race cars....like a 5.0 liter 4 cylinder twin turbo "Integra" funny car.


275hp & 306tq - 1999 2.2 ohv
13.2 @ 108 mph
-1996 2.4 liter + Turbo + Built motor + Torco + More boost = Lots o' Power
-2000 Mustang GT + 2004 Cobra motor, Whipple 2.3 supercharger,
built rear-end,Dodge Viper spec T56 6 speed, bolt-ons = wheelies at the track!!!!!

Quote:

I am having a dispute about turboing a high comp ratio application as appose to a low comp application. Yes lower means better psi levels and high means greater chance of "BOOM". what is more efficient high or low compression? this is a need to know kind of thing here not a Q on how I would turbo my car. MY BROTHER SEEMS TO Want TO KNOW HOW efficient THIS WOULD BE NOT HOW MUCH LOW COMP WOULD BETTER BENIFET THE TURBO AND ITS power output

HIGH compression and boost will net more power. the only problem ass far as stopping detonation is that pump fuel will only work so much. if u want to run race fuel all the time or C16, then go for it

its all about your effective compressin ratio. lower compression allows more boost for the sam amout as high compression with low boost. for exampl: 8.5:1 compression with 12lb boost has say an effective compression of 14:1 (example) then take a 10:1 compression and 6lb boost has the sam 14:1 effective comrerssion. do in the end your ending up with the same compression ratio. but remember more compression the more octane. --OCTANE=RESISTANCE TO DETONATION-- write that down.

you can easy run 11 to 1 compression ratio in our cars with say 15psi... BUT! only gas you will be able to run is like 106octane and you neeed an amazing tune.... but if you could get this to work... that a HIGH! horse power jbody i can tell you that much..

i used 11 to 1 as an example because i am talking with a guy who is also twin charging his car like mine is but running that compression but this guy builds engines for a living so i am sure he knows his @!#$...



The First Twin Charged jbody
blue car (R.I.P) - 240whp @7psi..
silver car - 305whp 315lbs.tq @15psi (91 Octane) or 420whp & 425lbs.TQ @20psi (94 octane+Alcohol Injection)
All dynos run on a Mustang dyno

It is possible but you don't want to go there with a street car.



Cardomain|Myspace

M I N I O N - Sinbird wrote:It is possible but you don't want to go there with a street car.

x 2


You'll notice that pretty much the only cars running higher than stock compression with boost are also on race gas, and get nifty trinkets like titanium engine components and the very best in engine management and tuning You can do it on a street car too, to an extent, but pump gas will only allow you to go so far, and in the end, the difference between a high comp, med. boost and stock or lower comp/high boost setup on pump gas won't be significant enough to make the hours of tuning required to ensure no detonation worth it.

But, since your question was really, is it more efficient to do higher compression, lower boost, yes, that is correct assuming proper fuel and tuning.




Arrival Blue 04 LS Sport
Eco
Turbo
Megasquirt
'Nuff said

Adler wrote:

Hunter wrote:Bob Norwood took a Ferrari F50, with an 11:1 compression ratio, and twin turbocharged it, around 15psi. He used a Motec standalone to control it all, high effciency water to air intercoolers and instead of gaslone, he used E80 as a fuel.

If it is the same car that I am thinking of, the guy who owns the F50 was one of the creaters of the video game DOOM. I have actually seen the guy driving the car on the street a few times. And if you are ever able to go over to Bob Norwood's house, you will see some crazy ass race cars....like a 5.0 liter 4 cylinder twin turbo "Integra" funny car.

Ya thats the car. Bob Norwood has some siiiiick cars...never been to his house, but I have met him once at Bonneville when he was racing his Ferrari 308 with a TT Chevy Bigblock in it.


1988 Pontiac Fiero, engine transplant underway.
2004 ECOtec, built and boosted

Here are some pics of Bob Norwood doing the 360hp tune on Mike Kara's 2.4.....Take notice the Ferrari shirt








275hp & 306tq - 1999 2.2 ohv
13.2 @ 108 mph
-1996 2.4 liter + Turbo + Built motor + Torco + More boost = Lots o' Power
-2000 Mustang GT + 2004 Cobra motor, Whipple 2.3 supercharger,
built rear-end,Dodge Viper spec T56 6 speed, bolt-ons = wheelies at the track!!!!!

Yes you can tune a car for boost with higher compression. You will definitely notice faster throttle response, and a lot more power out of the box. However, you suffer high EGT's and you can't exactly run pump gas. Not the best way to go for a street car.




I was a retard, and now I'm permanently banned.

Well you don't necessarily have to run race fuel to run high compression with boost just use efficient intercooling with water/methanol injection and good tuning. I have a Monte Carlo SS with a 383 10.5:1 static cr with 12# - 13# of intercooled boost with boost referenced water/methanol injection making 850hp on pump gas that can be driven daily if needed. I'm planning to turbo my 2000 Z24 with a ported head , secret cams, extrude honed HO intake, 62mm tb,T3/T40E 57 trim turbo, jtuners turbo manifold, fmic, bigger injectors, 8psi on stock bottom end (for now more after building a new engine) and a custom tune for my setup. hoping to make 275 - 350 hp on stock bottom end.


2000 Z24 5spd header & catback for now.

...........and here is a video that I just found of Bob Norwood's Acura Integra with a twin turbo 5.0 liter 4 clyinder that was on the History Channel.

http://videos.streetfire.net/hottestvideos/1/wm/EF72972B-1543-4C67-A00E-052C936F472C.htm


275hp & 306tq - 1999 2.2 ohv
13.2 @ 108 mph
-1996 2.4 liter + Turbo + Built motor + Torco + More boost = Lots o' Power
-2000 Mustang GT + 2004 Cobra motor, Whipple 2.3 supercharger,
built rear-end,Dodge Viper spec T56 6 speed, bolt-ons = wheelies at the track!!!!!