2012 SS N/A Build

[morepowerjoe]

Originally Posted by Vicster

Hello,

If you are planning to add boost I would not go above 10-1 compression. My LSA and 427ci are around 9.5-1 compression.

Do you know how much horsepower loss I would see N/A with 11.1 to 10.1 because that's a big decision for me? A full point of compression seems like it would be pretty big N/A. One thing is I don't know how far down the road boost will be in my future. It could be a year from now or three years. Another thing that I have to consider is the ring end gap. Will the bigger gap right now hurt anything like my cats and will it burn more oil?

Thanks Vic

[morepowerjoe]

I stole this from an old thread from 2009. Tell me if this does or does not make sense?
This issue comes up because when you lower compression ratio with a centrifugal supercharger, you disproportionately affect the low end of the power range. That is, the engine has lower power at pre-boost rpm, even though it is much more powerful at post-boost rpm. The solution would seem quite naturally to be higher compression with lower boost.

[morepowerjoe]

Ok so I've been reading up on compression versus boost applications and it seems like 10.1 to 11.1 is only about 20 hp. So I think that is acceptable to me and be able to run around 10psi safely (correct me if I'm wrong). But I've also read with a very good tune 11.1 is ok but again with a very good tune, which I have one of the best if not the best tuner in Austin. I just don't know how much boost I could run at 10.1 or 11.1. I know a lot of people run 10-12 lbs. of boost all the time on stock ls3's with the stock compression being at 10.7.1. Sorry just up late thinking about all of this

[Vicster]

No problem, but be careful it can drive you crazy!
I get 20mpg on the highway with approx. 1100hp. I feel that dropping the power at low rpm helps with fuel economy and for street drivabilty. If I was building a drag car I would go turbos as the power off the line is lower and climbs with rpm's. Superchargers are great for the track they hit hard at lower rpms and fall off at higher rpm's. Also the higher the compression pressure rises so does the problems of knock and detonation.

Everyone has an idea on what they want for throttle response and power levels, which I think is great! Or we would all have the same thing... Just remember as your power levels go up, so does the requirements for drive train and suspension upgrades.

[morepowerjoe]

Originally Posted by Vicster

No problem, I get 20mpg on the highway with approx. 1100hp. I feel that dropping the power at low rpm helps with fuel economy and for street drivabilty. If I was building a drag car I would go turbos as the power off the line is lower and climbs with rpm's. Superchargers are great for the track they hit hard at lower rpms and fall off at higher rpm's. Also the higher the compression pressure rises so does the problems of knock and detonation.

Everyone has an idea on what they want for throttle response and power levels, which I think is great! Or we would all have the same thing... Just remember as your power levels go up, so does the requirements for drive train and suspension upgrades.

Like I said before that’s an insane amount of power for the road but unfortunately mine will be my daily so I'm not sure if yours is that streetable (and I'm not saying that yours isn't) . I Just want a fun ride for the moment and 500 whp might do it for me I'll just have to wait and see. Like you were saying all the other mods that I will have to do are a ways away anyway so I think that they are anyways but you never know what life will do for you. I think that I will go ahead with the 11.1 compression and if I decide to go boost I can always change the heads back to a stock height and then be back down to 10.3.1 or go with a 70cc chamber size foe more of a reduced compression ratio. Thanks for your input Vic I appreciate it.

[Vicster]

Originally Posted by morepowerjoe

Do you know how much horsepower loss I would see N/A with 11.1 to 10.1 because that's a big decision for me? A full point of compression seems like it would be pretty big N/A. One thing is I don't know how far down the road boost will be in my future. It could be a year from now or three years. Another thing that I have to consider is the ring end gap. Will the bigger gap right now hurt anything like my cats and will it burn more oil?

Thanks Vic

If you know you are going to add forced air, go with the larger piston ring gap. I run large gaps 0.026" on top I am planning on 18 psi boost. But that depends on the heads and cam, as increased flow lowers the intake pressure. You only need to see one engine come apart due to rings being set to tight. Usually ends up being total engine loss.

Also centrilfugal blowers need a more specific cam profile to get the most out of it. With ported heads something like this.

https://cammotion.com/camshafts/cs-2...r-centrifugal/

Just remember this is just my personal feelings, ask 100 mechanics you will get 100 different answers.

[morepowerjoe]

That cam is really similar to the GPI SS3 vvt cam that I'm going to use. The SS3 vvt just has a bit more lift.

[Vicster]

Originally Posted by morepowerjoe

Like I said before that’s an insane amount of power for the road but unfortunately mine will be my daily so I'm not sure if yours is that streetable (and I'm not saying that yours isn't) . I Just want a fun ride for the moment and 500 whp might do it for me I'll just have to wait and see. Like you were saying all the other mods that I will have to do are a ways away anyway so I think that they are anyways but you never know what life will do for you. I think that I will go ahead with the 11.1 compression and if I decide to go boost I can always change the heads back to a stock height and then be back down to 10.3.1 or go with a 70cc chamber size foe more of a reduced compression ratio. Thanks for your input Vic I appreciate it.

Sounds like you know what you want! That is the hardest thing to figure out! You are most welcome!

[morepowerjoe]

It has begun.

[morepowerjoe]

Talked to machinist today and we discussed ring end gap. He set my worries at ease. I'm definitely new to the boost scene but was wondering if the 24/26 versus the traditional 18/20 N/A ring end gap would consume more oil or lose power and he said no. So, I went ahead and told him to do the 24/26 gaps for boost or maybe even nitrous later on. Now my block will be able to handle all
I want to through at it although I still have the stock crank being my only weak point, but it should hold up for a big number I just don't really know how much. Everything that I've read says it's capable of 900-1000 crank hp maybe a little more. That should be good for me because I don't think I even want that much power anyways, but you never know.

[Vicster]

Originally Posted by morepowerjoe

It has begun.

Awsome!!!

[Risingson05]

Originally Posted by morepowerjoe

It has begun.
Attachment 1109981
Attachment 1109982

Haha.. man that block sure is purdy !! ..

[morepowerjoe]

Originally Posted by Risingson05

Haha.. man that block sure is purdy !! ..

Thank you sir.

[morepowerjoe]

For cooling I'm going to use the Mishimoto oil cooler kit (https://www.mishimoto.com/chevrolet-...2010-2015.html) (doing factory oil cooler delete) with a Tru Cool 40k tranny cooler and a Lingenfelter T-stat (https://www.summitracing.com/parts/LPE-L310155307). I think when I need to I will get a Mishimoto radiator too.