I just want to know who's running them and any problems they are having.

I run meth and have HPT so I think that should cover the basics.

 

why would you want to raise the compression on your boosted engine?

 

Throw on some ARP Head Studs and a Cometic Head gasket and you could be making some nice numbers with that blower. nothing wrong with higher compression. dont listen to everyone who says higher compression is bad, it isnt if done right. mild boost + higher compression = more power then them =P

 

well, with 271 hp i'm guessing he's not putting out "mild" boost.

 

yea. what he said.. if your goal is boost, instead of performance, then lower ratio is what you want.. ive seen a boosted K20 runnin 11 to 1 ratio makin 350+whp on 13 psi. I guess its just easier turnin up the boost with a lower comp. then fine tuning with the higher comp

 

well I've gone uping the boost, so now I think I want to try something different with low boost. This will help keep the SC in its efficiency range.

 

Also understand that you are going to be increasing combustion chamber temperatures by raising the compression. You would also need to fine tune ignition timing depending on how much of an advance it is currently.

You'd also probably want to run richer as well.

You'd be better off going with a more efficient compressor which would yield more power than your supercharger even with higher compression. Another thing to think about, how much air is being delivered into the combustion chamber (talking about your valvetrain) per intake stroke.

Higher octane would be needed as well to avoid knocking.

I think you're really pushing it with that high. Even the J-bodies with the M62 start seeing knocking issues when they reach 3.0" or under.

(Note: The L61 motor is 10.0:1 compression)

 

Rice eater from the RL forums, has 10.5:1 compression with a 2.6" pulley.

...he has to run a minimum of 100 octane, all the time...

 

As long a it doesn't knock during regular driving I am happy.

oh yea

What's going on with his car anyways?

 

Mase, if you care about efficiency and you recognize that raising the compression (just for example sakes) will put you in the temperature range of a 2.5" pulley, why go this route? Less boost or more boost, it's overall about the temperature inside the combustion chamber.

You actually COULD knock in vacuum or with very low boost pressure.

As far as running rich, remember the whole issue with having a return-less fuel system...

One last thing

If you have to use Meth Injection on a constant basis to keep temps down, there IS a problem. It should be a helper, not a must have.

 

I know what you're saying about heat inside the motor.

One of the main reasons I want to go with 10.5:1 is due to the 2.4L. The solstice I tuned made 311RWHP at only 8psi. Now I know they have more displacement, but in comparison to the turbo cobalt which made 323WHP at the front on 18psi, I'm thinking these motors like compression more than boost.

 

It's not necessarily of what the engine likes...

You're comparing a Turbocharged Unit to your Supercharger unit. Even with your supercharger staying within it's efficiency range, it does not compare to a properly sized turbocharger as far as how much air (CFM) is being produced AND the parasitic loss that you're having when it comes to turning the supercharger. Displacement defenitley does play an effect as well...there is a slight bore increase over your engine but it's mostly the stroke that's the difference, this means more air and higher VE.

It's hard to really compare 2 setups and try to say that they are slightly similar because even if it was the same engine as yours, you're not going to duplicate it's results.

 

If you wanna run low boost, increase ignition timing rather than compression ratio. You'll see larger gains.

People that are running higher comp pistons are doing so because of aggressive cams.

 

You make my cam aggressive...grr

 

My cams are going to be far past aggressive, more like, "WHAT? Your actually gonna drive that on the street!?!?" 9.5:1 compression FTMFW!!! 15 psi with a 2.6" pulley FTMFW!!!! Boost/Heat equal to a 2.9" pulley, but the CFM of a 2.6", can't beat that!

 

are you going to run any other cooling mods or just keep the ones you have

 

Adding a dry ice box/extra coolant resevior, most likely 3/4 to 1 gallon in capacity. Plus I'm thinkin about a 100 shot of nitrous until I get the twin screw, hey it works for the Cobra guys.

 

Adding compression and lowering boost will grant you the same power as when you had higher boost and lower compression. The benefits are that your spinning the SC slower which = less parasitic loss, and the roots type you use is less and less efficient the faster you spin it. Turbo's its cool to lower comp, but roots type equipped cars love comp.

10.5 is damn high btw

 

Yeah adding compression and lowering boost will help keep the SC in its best efficiency. However, 10.5:1 is probably gonna be too high to run the car on anything lower then 100 octane.

 

Wow some people who actually think like i do. I was blasted over at the redline forums because i'm going with SRP 8:1's and a custom whipple at 20psi.

 

Tell me, was the head of the attack on you by chance AlphaJaguar? He TRIED to blast me when I posted about my blower porting! He blasts everyone, and says he has 300 whp with no dyno to prove it.

 

He was one of them trying to tell me that i was "Retarded" for wanting to drop compression that much and i should stick to around stock compression for 20psi of boost.

One of the reasons why i came over here. Lots of knowledgeable people here.

 

I was thinking of going 8.8:1 compression...I just haven't found the pistons.

 

Is That Really Tempe Az I See On Your Location!?!? **** Man Im From Chandler!!!

 

I bought 10:5:1 pistons which Rob Archer told me he was going to do before he had to get rid of the car. Now after reading everything and I talked to Todd at Intense I don't know if I want them anymore. Should I sell them or give them a try? I really don't want to run 100 octane. I run only 94 now so I don't really want to go above that. Any advice would be appreciated.