Got into a debate with a Ford guy today about high compression and boost..
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From: Germantown, MD
Originally Posted by eviltwins
If a 14:1 nitrous motor can spray 2, 3, 400 horsepower worth of juice, why can't you boost an 11.75:1 motor? They're both adding air, it's practically the same thing once it's in the chamber.
To the poster, I'm sure it could be done, but who cares. Is it the optimum configuration for a boosted car? I seriously doubt it.
Mike
Thread Starter
Joined: Nov 2001
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From: Valrico, Florida
Originally Posted by Got Me SOM
just get some 325/50/15 M/t drag radials Vince and that' bitch will hook. 
When ya gonna bring that car to Orlando?
When ya gonna bring that car to Orlando? Awesome man, hang in there take advantage of the OT while its there, maybe 17 inch Mickey's will do the trick? Caveman aka Dave with the Red Formula has a set and let me tell you that is a gummy sticky tire, so sticky its hard to get it off your car!
no traction on a small nitrous shot...yet you want booost lol
anyways think about the RX car IFlyubye car. D1 blower car with 10/1 compression 346 on pump gas. just short of 600 rwhp on a very safe tune.
anyways think about the RX car IFlyubye car. D1 blower car with 10/1 compression 346 on pump gas. just short of 600 rwhp on a very safe tune.
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From: Hazard Co. Maryland
Originally Posted by gator's 99TA
anyways think about the RX car IFlyubye car. D1 blower car with 10/1 compression 346 on pump gas. just short of 600 rwhp on a very safe tune.
Yes it can be done but if you have the choice with a forced induction car, drop the comp. and turn the boost up.
Thread Starter
Joined: Nov 2001
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From: Valrico, Florida
Originally Posted by Got Me SOM
Awesome man, hang in there take advantage of the OT while its there, maybe 17 inch Mickey's will do the trick? Caveman aka Dave with the Red Formula has a set and let me tell you that is a gummy sticky tire, so sticky its hard to get it off your car!
They do hook for sure. I will keep you posted on it.. LS1 Tech Stories
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Originally Posted by sb427f-car
But it still comes down to the equation of power per # of boost. What are the calculations, 1 full point in compression gives you a 15% increase in power where as 1 lb of boost allows roughly 40 HP (give or take and depending upon application). If you drop the compression one full point you can run more than one more additional lb of boost. If boost is the limiting factor (IE you can't run any more of it) and timing being equal as well...sure, run more compression. Yes, Nitro motors aren't an equal example but why do you think those guys run 60#s of air into the motor rather than dropping it down to say 40#s and run 8:1 compression (not relative I know)? But it's because they can get more out of it with less compression and more boost. Besides, the effective compression ratio increases too.
While Nitrous does cool down the intake charge, once it gets into the combustion chamber the result is the same; higher cylinder pressures, creating the need for more fuel and more octane. You're right, a flat top piston is much less prone to detonation and produces a better flame front than a dome top, but I'll bet you money that his 11.7:1 408 is using a flat top piston. And 1 point in compression is give or take 3-4% in total power output, not 15.
I still believe a high compression forced induction setup can run very well on the street. A friend of mine just finished a mod motor ford car to run PSCA heavy street, it's 10.5:1 compression and we've had it up to 32-33 pounds of boost on C16 so far. NMRA renegade cars are fairly limited by the blower's (YSi is about the biggest, and they must run 8-rib serpentine, and NO intercoolers) so they have found other ways to make power. Can you guess what that is? Higher compression. Some around 10.5:1, and pushing over 30 pounds of non intercooled boost into their motor. I don't believe nitrous "loves" high compression, because which cars do you always see with burnt pistons at races? The ultra high compression nitrous guys. Rarely do you see a blower/turbo guy destroying pistons. Nitrous is just as finnicky in a high boost race gas setup as a blower/turbo is, in my humble opinion.
Staging Lane
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Well fellas I am one of them ford boys 
(not the one he talked to)
I run 10.25.1 comp in my 308 with 10psi Non intercooled 11.8AF with 20* total timing at WOT
This mustang runs fairly high comp around 10.25.1 and 28+ lbs of boost
They are a few local guys here in town who won the WFC this year.
http://inductionweb.com/UndrPrsr2.mpg
But like said earler there are alot more vairbles involved!!
And some times its alot harder to hit 35-40 lbs of boost vs just uppin the comp just a little. To get the same power.
But in most cases 8.5.1 comp with alot of boost is IDEAL
(not the one he talked to)I run 10.25.1 comp in my 308 with 10psi Non intercooled 11.8AF with 20* total timing at WOT
This mustang runs fairly high comp around 10.25.1 and 28+ lbs of boost
They are a few local guys here in town who won the WFC this year.
http://inductionweb.com/UndrPrsr2.mpg
But like said earler there are alot more vairbles involved!!
And some times its alot harder to hit 35-40 lbs of boost vs just uppin the comp just a little. To get the same power.
But in most cases 8.5.1 comp with alot of boost is IDEAL
Last edited by GenofiveO; Apr 6, 2005 at 07:25 PM. Reason: change
Staging Lane
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Also tell him that the theoretical compression is ASTRONOMICAL! Especially when more power can be made with less compression, cheaper gas, and WAY more boost. There is a reason Top Fuel and Funny car nitro motors run CRs aroun 6:1, because they can pack more boost in the cylinders safer.
Because its not how you get there, Its who gets there first!!!! Thats why i drive a FORD
(flame away) lol!! 
Originally Posted by GenofiveO
Well fellas I am one of them ford boys (not the one he talked to)
I run 10.25.1 comp in my 308 with 10psi Non intercooled 11.8AF with 20* total timing at WOT
This mustang runs fairly high comp around 10.25.1 and 28+ lbs of boost
They are a few local guys here in town who won the WFC this year.
http://inductionweb.com/UndrPrsr2.mpg
But like said earler there are alot more vairbles involved!!
And some times its alot harder to hit 35-40 lbs of boost vs just uppin the comp just a little. To get the same power.
But in most cases 8.5.1 comp with alot of boost is IDEAL
(not the one he talked to)I run 10.25.1 comp in my 308 with 10psi Non intercooled 11.8AF with 20* total timing at WOT
This mustang runs fairly high comp around 10.25.1 and 28+ lbs of boost
They are a few local guys here in town who won the WFC this year.
http://inductionweb.com/UndrPrsr2.mpg
But like said earler there are alot more vairbles involved!!
And some times its alot harder to hit 35-40 lbs of boost vs just uppin the comp just a little. To get the same power.
But in most cases 8.5.1 comp with alot of boost is IDEAL
Awesome vid man! That thing must be fun to drive
well im convinced now, i gotta go get me a F4R blower, and some 16:1 domed pistons, and run about 30psi..
I wont even cheat and use alky, just 93 octane, and some 42lbhr injectors, whatll you all say?
ed
I wont even cheat and use alky, just 93 octane, and some 42lbhr injectors, whatll you all say?
ed
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From: Hazard Co. Maryland
Originally Posted by 69firebird
well im convinced now, i gotta go get me a F4R blower, and some 16:1 domed pistons, and run about 30psi..
I wont even cheat and use alky, just 93 octane, and some 42lbhr injectors, whatll you all say?
ed
I wont even cheat and use alky, just 93 octane, and some 42lbhr injectors, whatll you all say?
ed
Good luck with that, I hope your budget is REAL big
lol.Evil...obviously with in limits. The thing is...there isn't much room for error on a setup like that if it doesn't knock retard quick enough (assuming you have knock sensors) or if a compressor surges with a turbo. Also...it does come down to a lot of piston and head design. Ever stop to think that perhaps the heads on a 5 liter are better suited for a good amount of quench? I know a few people on here that are running stock internals and on P1SCs that have a 10# pulley on there and a good tune that run on pump gas with no problems, but as I said above in this post...very fine line.
Originally Posted by GenofiveO
If this were the case how come every peformance car and drag racer out there is not running 2.5.1 comp and 100+psi of boost
Because its not how you get there, Its who gets there first!!!! Thats why i drive a FORD (flame away) lol!!
Because its not how you get there, Its who gets there first!!!! Thats why i drive a FORD
(flame away) lol!! 
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Originally Posted by sb427f-car
Good luck with that, I hope your budget is REAL big lol.
Evil...obviously with in limits. The thing is...there isn't much room for error on a setup like that if it doesn't knock retard quick enough (assuming you have knock sensors) or if a compressor surges with a turbo. Also...it does come down to a lot of piston and head design. Ever stop to think that perhaps the heads on a 5 liter are better suited for a good amount of quench? I know a few people on here that are running stock internals and on P1SCs that have a 10# pulley on there and a good tune that run on pump gas with no problems, but as I said above in this post...very fine line.
lol.Evil...obviously with in limits. The thing is...there isn't much room for error on a setup like that if it doesn't knock retard quick enough (assuming you have knock sensors) or if a compressor surges with a turbo. Also...it does come down to a lot of piston and head design. Ever stop to think that perhaps the heads on a 5 liter are better suited for a good amount of quench? I know a few people on here that are running stock internals and on P1SCs that have a 10# pulley on there and a good tune that run on pump gas with no problems, but as I said above in this post...very fine line.
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From: Downers Grove,IL
Blown Nitro motors need lower compression because of the sheer amount of fluid entering the cyl. Nitro runs at around a 2-1 AF and can even be considered a mono propellant. It's possible to hydraulic lock the cyl so they need space for all that fluid volume. Should not even be remotely compared with a gas burning motor.
The ls1 and Ford heads are actually pretty similar. But if we are to say the ls1 chamber is superior and burns faster, that just means it's possible to run the same high compression with less chance of detonation.
The slower a chamber burns the more chance of detonation from the end gasses.
Steve
The ls1 and Ford heads are actually pretty similar. But if we are to say the ls1 chamber is superior and burns faster, that just means it's possible to run the same high compression with less chance of detonation.
The slower a chamber burns the more chance of detonation from the end gasses.
Steve
The slower a chamber burns the more chance of detonation from the end gasses.