Low Compression N/A Build opinions
07-16-2008, 12:19 PM
#1
Staging Lane
Thread Starter
Join Date: Jul 2008
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
Low Compression N/A Build opinions I am considering doing a N/A 454lsx engine. Eventually in a few years I want to do a F/I setup, but for the meantime a N/A N20 build will suffice.
This is my question, if I build the motor to something like 8.7:1 compression ratio for the future F/I build will this work fine minus the roughly 3-4% loss per compression point?
For example i see alot of 454lsx motors putting out 550rwhp, will my 3 pts of compression really kill around 60rwhp? I have heard other issues such as torque loss etc..
Plans are E85 tune, Big Cam, good flowing heads, 2" headers etc...
Whats your input?
I hate to lose all that hp, but pulling out the motor in a couple years and rebuilding for low compression doesnt sound like much of an option.
This is my question, if I build the motor to something like 8.7:1 compression ratio for the future F/I build will this work fine minus the roughly 3-4% loss per compression point?
For example i see alot of 454lsx motors putting out 550rwhp, will my 3 pts of compression really kill around 60rwhp? I have heard other issues such as torque loss etc..
Plans are E85 tune, Big Cam, good flowing heads, 2" headers etc...
Whats your input?
I hate to lose all that hp, but pulling out the motor in a couple years and rebuilding for low compression doesnt sound like much of an option.
Last edited by Bucktooth; 07-16-2008 at 12:25 PM.
07-16-2008, 01:23 PM
#2
E85 and low compression are not good bed fellows.
If it were me. I would build to about 10:1, run gasoline for now and when you get ready to boost the motor, switch to e-85. Optimal for neither, but compromises rarely are.
Or if you want run a smaller combustion chamber on your heads for now and when you get ready to boost the motor, pull the heads and replace with larger ones.
These are just options. You need to figure out hom much you want out of it after it is boosted. When you really turn the wick up, ring selection changes. Like I said earlier compromises are never the best for either of the things compromised.
If it were me. I would build to about 10:1, run gasoline for now and when you get ready to boost the motor, switch to e-85. Optimal for neither, but compromises rarely are.
Or if you want run a smaller combustion chamber on your heads for now and when you get ready to boost the motor, pull the heads and replace with larger ones.
These are just options. You need to figure out hom much you want out of it after it is boosted. When you really turn the wick up, ring selection changes. Like I said earlier compromises are never the best for either of the things compromised.
07-16-2008, 03:06 PM
#3
Staging Lane
Thread Starter
Join Date: Jul 2008
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
Can you use boosted rings for non boosted applications? Or is that a dumb question? They prly wouldnt seat well i would imagine.
Might have to consider switching pistons at a later date and run close to 12:1 compression now....
Might have to consider switching pistons at a later date and run close to 12:1 compression now....
07-17-2008, 11:20 AM
#6
FormerVendor
I was talking to them and Wiseco has this piston available which could set you up in NA form at least. You'd probably need a real blower piston if you want to make big power later but of it's for a few years I would rather have the right pistons for NA during that time.
""The k462f185 piston has a -3cc .215 tall solid dome and nets about 12.0 with a 70cc head and the typical 4.185 bore/4.125 stroke. That same piston with the dome leveled off to flat top nets -7cc. That's an 11g difference in gram weight and wouldn't affect balance badly, but would drop the compression about 1/2 a point without affecting the strength of the piston.""
If not probably as Stang's Bane said you could do something that would be somewhere in between.
Starting with a 72cc chamber shouldn't be tough to find and would net a 11.9 ratio to start and 11.4:1 after the mill. There are quite a few people running boost w/ e85 at 11 to 11.5:1 with no issues.
""The k462f185 piston has a -3cc .215 tall solid dome and nets about 12.0 with a 70cc head and the typical 4.185 bore/4.125 stroke. That same piston with the dome leveled off to flat top nets -7cc. That's an 11g difference in gram weight and wouldn't affect balance badly, but would drop the compression about 1/2 a point without affecting the strength of the piston.""
If not probably as Stang's Bane said you could do something that would be somewhere in between.
Starting with a 72cc chamber shouldn't be tough to find and would net a 11.9 ratio to start and 11.4:1 after the mill. There are quite a few people running boost w/ e85 at 11 to 11.5:1 with no issues.
07-17-2008, 11:39 AM
#7
I was talking to them and Wiseco has this piston available which could set you up in NA form at least. You'd probably need a real blower piston if you want to make big power later but of it's for a few years I would rather have the right pistons for NA during that time.
""The k462f185 piston has a -3cc .215 tall solid dome and nets about 12.0 with a 70cc head and the typical 4.185 bore/4.125 stroke. That same piston with the dome leveled off to flat top nets -7cc. That's an 11g difference in gram weight and wouldn't affect balance badly, but would drop the compression about 1/2 a point without affecting the strength of the piston.""
If not probably as Stang's Bane said you could do something that would be somewhere in between.
Starting with a 72cc chamber shouldn't be tough to find and would net a 11.9 ratio to start and 11.4:1 after the mill. There are quite a few people running boost w/ e85 at 11 to 11.5:1 with no issues.
""The k462f185 piston has a -3cc .215 tall solid dome and nets about 12.0 with a 70cc head and the typical 4.185 bore/4.125 stroke. That same piston with the dome leveled off to flat top nets -7cc. That's an 11g difference in gram weight and wouldn't affect balance badly, but would drop the compression about 1/2 a point without affecting the strength of the piston.""
If not probably as Stang's Bane said you could do something that would be somewhere in between.
Starting with a 72cc chamber shouldn't be tough to find and would net a 11.9 ratio to start and 11.4:1 after the mill. There are quite a few people running boost w/ e85 at 11 to 11.5:1 with no issues.
Trending Topics
07-17-2008, 11:46 AM
#8
FormerVendor
Oh I would drop the compression to maybe 9.5 to 1 for boost and run a different piston but I know you can run a little more that that with E85 although I would just keep that as detonation insurance and not go crazy on the boost compression.
07-21-2008, 06:48 AM
#11
Staging Lane
Thread Starter
Join Date: Jul 2008
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
I was talking to them and Wiseco has this piston available which could set you up in NA form at least. You'd probably need a real blower piston if you want to make big power later but of it's for a few years I would rather have the right pistons for NA during that time.
""The k462f185 piston has a -3cc .215 tall solid dome and nets about 12.0 with a 70cc head and the typical 4.185 bore/4.125 stroke. That same piston with the dome leveled off to flat top nets -7cc. That's an 11g difference in gram weight and wouldn't affect balance badly, but would drop the compression about 1/2 a point without affecting the strength of the piston.""
If not probably as Stang's Bane said you could do something that would be somewhere in between.
Starting with a 72cc chamber shouldn't be tough to find and would net a 11.9 ratio to start and 11.4:1 after the mill. There are quite a few people running boost w/ e85 at 11 to 11.5:1 with no issues.
""The k462f185 piston has a -3cc .215 tall solid dome and nets about 12.0 with a 70cc head and the typical 4.185 bore/4.125 stroke. That same piston with the dome leveled off to flat top nets -7cc. That's an 11g difference in gram weight and wouldn't affect balance badly, but would drop the compression about 1/2 a point without affecting the strength of the piston.""
If not probably as Stang's Bane said you could do something that would be somewhere in between.
Starting with a 72cc chamber shouldn't be tough to find and would net a 11.9 ratio to start and 11.4:1 after the mill. There are quite a few people running boost w/ e85 at 11 to 11.5:1 with no issues.
So cant i put in a real blower piston now? Ill be shooting it with plenty of N2O.
07-21-2008, 10:58 PM
#13
Staging Lane
Thread Starter
Join Date: Jul 2008
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts