low compression 2v question

joshdj13 · November 13th, 2011, 03:29 PM

i havent heard about anyone running a low compression 2v and am interested to see if anyone is. i know they make less hp n/a but will they make alot more f/i like the termi's. just a question to pick your brains.

sharkbait · November 13th, 2011, 03:33 PM

they wont make "more FI"

they'll just be able to make more FI with less chance of detonation. Termis run like what 8.5 compared to the regular 9.0?

na svt · November 13th, 2011, 03:44 PM

lower compression means lower hp, lower tq, less power when off boost and reduced driveability.

joshdj13 · November 13th, 2011, 04:03 PM

ok thanks, i was under the impression that a low compression engine made more than stock compression at the same boost level.

sharkbait · November 13th, 2011, 04:06 PM

for every point of compression i think it makes 4% more power. So going to stock cobra compression you would lose 4% power over a comparable car at stock compression.

mustanginky · November 13th, 2011, 04:08 PM

no it will make less. more compression will always =more horsepower. it's just at what cost. everything has a trade off. higher compression will net you more power, but less safety with a blower/turbo. lower compression will resist detonation better, but will take more timing to make the same power, which can offset.

in todays world with better tuners/tuning abilities, there really isn't a reason to go to a lower compression unless you're planning on 20 psi or more.

joshdj13 · November 13th, 2011, 04:38 PM

Originally Posted by mustanginky

no it will make less. more compression will always =more horsepower. it's just at what cost. everything has a trade off. higher compression will net you more power, but less safety with a blower/turbo. lower compression will resist detonation better, but will take more timing to make the same power, which can offset.

in todays world with better tuners/tuning abilities, there really isn't a reason to go to a lower compression unless you're planning on 20 psi or more.

thats what i needed to know. thanks

codycat91 · November 13th, 2011, 04:59 PM

The only reason you think that is because cars with lower CR's can run more boost, giving more power. A high compression car at high boost has a high chance of detonation. So the lower the CR, the more potential for boost (you can have high CR and higher boost with meth and/or high octane race fuel or even E85).

So the lower the CR, the better for more boost to a certain point. I think anything under 8.0:1 is pointless in and out of boost and shows no benefits over slightly higher CR.

Shaun03GT · November 13th, 2011, 05:56 PM

Low compression with boost is old news. The only good thing is with lower compression, you can run more boost and timing without getting detonation. Not much more, but higher compression with more boost will require race gas.

na svt · November 13th, 2011, 06:06 PM

10:1 with 14psi is very safe and can be run on93 octane.

At 14psi an 8.5:1cr combo will be down 50rwhp/50rwtq when compared to a 10:1cr engine.

November 13th, 2011, 03:29 PM	#1
joshdj13 Enthusiast 02 gt 5 speed 13.7 @96 stock Join Date: Mar 2011 Location: ga Posts: 613 iTrader: 0 reviews	low compression 2v question i havent heard about anyone running a low compression 2v and am interested to see if anyone is. i know they make less hp n/a but will they make alot more f/i like the termi's. just a question to pick your brains.

November 13th, 2011, 03:33 PM	#2
sharkbait Hooo Ha Ha 1997 Mustang GT 11.65 @ 115 Join Date: Apr 2009 Location: Pasadena MD Posts: 9,743 iTrader: 10 reviews	they wont make "more FI" they'll just be able to make more FI with less chance of detonation. Termis run like what 8.5 compared to the regular 9.0? __________________ 410rwhp 520rwtq @ 12.9 psi

November 13th, 2011, 04:06 PM	#5
sharkbait Hooo Ha Ha 1997 Mustang GT 11.65 @ 115 Join Date: Apr 2009 Location: Pasadena MD Posts: 9,743 iTrader: 10 reviews	for every point of compression i think it makes 4% more power. So going to stock cobra compression you would lose 4% power over a comparable car at stock compression. __________________ 410rwhp 520rwtq @ 12.9 psi

November 13th, 2011, 04:08 PM	#6
mustanginky MM Fanatic 2000 gt Join Date: Feb 2009 Location: La grange, KY Posts: 4,259 iTrader: 2 reviews	no it will make less. more compression will always =more horsepower. it's just at what cost. everything has a trade off. higher compression will net you more power, but less safety with a blower/turbo. lower compression will resist detonation better, but will take more timing to make the same power, which can offset. in todays world with better tuners/tuning abilities, there really isn't a reason to go to a lower compression unless you're planning on 20 psi or more. __________________ Procharged 2000 5 Speed BAB GT, built motor, blower cams, speedy dyno tune 412 hp, 450 rw tq HARDCORE CREW BRIGHT ATLANTIC BLUE CREW #1 MEMBER

November 13th, 2011, 04:59 PM	#8
codycat91 MM Fanatic 2003 MUSTANG GT Join Date: Dec 2010 Location: Buffalo, NY Posts: 3,497 iTrader: 10 reviews	The only reason you think that is because cars with lower CR's can run more boost, giving more power. A high compression car at high boost has a high chance of detonation. So the lower the CR, the more potential for boost (you can have high CR and higher boost with meth and/or high octane race fuel or even E85). So the lower the CR, the better for more boost to a certain point. I think anything under 8.0:1 is pointless in and out of boost and shows no benefits over slightly higher CR. __________________ 4v MMR 4.75 Stroker, Teksid block .020 over, 9.27:1CR, Posi Race Ported Eaton 4v MMR Stroker 1000 / Posi Race Ported Eaton Build How To: 2v to 4v COP Swap

November 13th, 2011, 03:44 PM	#3
na svt 4v Know-it-all Join Date: Jan 2011 Posts: 488 iTrader: 0 reviews	lower compression means lower hp, lower tq, less power when off boost and reduced driveability.

November 13th, 2011, 04:03 PM	#4
joshdj13 Enthusiast 02 gt 5 speed 13.7 @96 stock Join Date: Mar 2011 Location: ga Posts: 613 iTrader: 0 reviews	ok thanks, i was under the impression that a low compression engine made more than stock compression at the same boost level.

November 13th, 2011, 05:56 PM	#9
Shaun03GT I Post Entirely Way Too Much 2003 Mustang GT 1/8 - 7.92 @ 91.13mph 1/4 - 12.21 @ 115.84mph Join Date: Sep 2009 Location: Weymouth, MA Posts: 13,444 iTrader: 12 reviews	Low compression with boost is old news. The only good thing is with lower compression, you can run more boost and timing without getting detonation. Not much more, but higher compression with more boost will require race gas. __________________ Vortech V1 Intercooled @ 11psi 394rwhp/392rwtq @ 9.5psi 415rwhp/400rwtq @ 11psi on Methanol Tuned By: Pete @ Performance Dyno Affordable Supercharger Build Guide Supercharger Info for Noobs

November 13th, 2011, 06:06 PM	#10
na svt 4v Know-it-all Join Date: Jan 2011 Posts: 488 iTrader: 0 reviews	10:1 with 14psi is very safe and can be run on93 octane. At 14psi an 8.5:1cr combo will be down 50rwhp/50rwtq when compared to a 10:1cr engine.

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