Lower compression or stock?
Thread Starter
Intermediate
Joined: Mar 2017
Posts: 26
Likes: 1
Lower compression or stock?
hey guys so the shop called me today and said i need to get pistons that are 5 though larger.
option is -2cc OR -12cc in the size i need
opinions? is lower compression better for boosted applications on a DI motor? will this affect anything i currently have?
ysi-b 2.7 pulley
stage 3 tsp blwoer cam
full valve train & manifold/tb setup
option is -2cc OR -12cc in the size i need
opinions? is lower compression better for boosted applications on a DI motor? will this affect anything i currently have?
ysi-b 2.7 pulley
stage 3 tsp blwoer cam
full valve train & manifold/tb setup
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
ttt
I wouldn't go any lower than 10:5 on it I don't know what ci bore you went with on your set up. I went with stock bore and went back with stock comp on it but did port the heads. Robert
Le Mans Master
Joined: Mar 2010
Posts: 7,050
Likes: 945
From: DFW TX
Advanced
Joined: Feb 2017
Posts: 99
Likes: 3
hey guys so the shop called me today and said i need to get pistons that are 5 though larger.
option is -2cc OR -12cc in the size i need
opinions? is lower compression better for boosted applications on a DI motor? will this affect anything i currently have?
ysi-b 2.7 pulley
stage 3 tsp blwoer cam
full valve train & manifold/tb setup
option is -2cc OR -12cc in the size i need
opinions? is lower compression better for boosted applications on a DI motor? will this affect anything i currently have?
ysi-b 2.7 pulley
stage 3 tsp blwoer cam
full valve train & manifold/tb setup
Le Mans Master
Joined: Mar 2010
Posts: 7,050
Likes: 945
From: DFW TX
No it doesn’t. Just about every boosted built motor you see from LME, Texas Speed, etc is 10.5:1 which is lower than stock. Thousands on the road including mine. Runs fine with a huge cam and all the boost.
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 921
From: Lehigh Acres FL
Tech Contributor
^^This. Don’t run 20+ psi on a stock compression motor. And by the way, the difference between those two piston options are not 10.5:1 and stock. Their actually 10.5:1 or 11.7:1 raising your compression slightly. Saying to use “stock” compression is just not the right answer here as Tim mentioned above.
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Le Mans Master
Joined: Oct 2010
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From: cold & windy
if you're turning the boost up a lot (15+), then lower compression will help as far as cylinder pressure is concerned, but that's also more for if you're planning on running around in high boost all the time because when compared to higher compression, you have more air in the cylinder at the same cylinder pressure. it also creates a larger tuning window before detonation. what you lose from it, though, is part-throttle response & efficiency.
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
ttt
if you're turning the boost up a lot (15+), then lower compression will help as far as cylinder pressure is concerned, but that's also more for if you're planning on running around in high boost all the time because when compared to higher compression, you have more air in the cylinder at the same cylinder pressure. it also creates a larger tuning window before detonation. what you lose from it, though, is part-throttle response & efficiency.
Former Vendor
Joined: Sep 2016
Posts: 1,397
Likes: 267
From: Houston Texas
At the end of the day we are talking about cylinder pressure to make hp. If you start out with a higher static comp. You will need less boost to make desired cylinder pressure. Lower boost means lower IATs which makes more power per psi of boost.
Billy
Billy
Thread Starter
Intermediate
Joined: Mar 2017
Posts: 26
Likes: 1
cam is a tsp stage 3
fueling is 94 daily and 105 on track
pulley on the ysi-b is a 2.7
car has the following mods:
dsx lowside
msd mainfold
ported tb
dual nozzel meth
co2 cooling system
tsp valve train
forged internals
rpm trans & diff
thats the highlevel gist of it
fueling is 94 daily and 105 on track
pulley on the ysi-b is a 2.7
car has the following mods:
dsx lowside
msd mainfold
ported tb
dual nozzel meth
co2 cooling system
tsp valve train
forged internals
rpm trans & diff
thats the highlevel gist of it
