im ordering manley h beam rods and wiseco 81.5mm pistons with a 9.7.1 ratio. my question is should i go with a lower compression ratio?

 

nah..you're just fine unless you live in an area with 91 octane swill.

 

some ppltell me i need to lower it and some say ill loose some throttle response? is lower better or more relaible?

 

what fuel do you plan on running this motor on? how much boost? power level? cams?

 

You are fine, im 9.8:1 and put close to 500 down with pump gas, if you plan on running race gas i would suggest lower, keep in mind cylinder pressure is cylinder pressure whether you run high comp/less boost or low comp/high boost

cheers

 

Ater the past few hours of searching i decided to go with 9.1 cp pistons. I always use 93 shell or sunoco but Im reading that ratio is more reliable. I believe i have type r cams and intake mani. Im hoping to push 19psi

 

19 psi is no issue with 93, you would get more HP if you ran higher compression and still be safe, if it's a daily driver your much better off going higher cp but up to you. Don't believe me call up Shaun at Church tuning.

good luck

 

Reliability is in your tuning, not your compression.

I'm at 10.4:1 on my turbo car for 7 years on 93 octane
I'm at 12.5:1 on my NA car for 4 years on 93 OCtane.

How you build and who builds is the X factor. not your compression

 

jeff evans is dyno tuning it. So should i use 9.7.1 or 9.1

 

if its a daily driver go with the higher cr which will make driving around town much more fun, that is my opinion. Like Pete said its all about how its put together and the tune.

 

how much power are you going for? I saw you said 19psi but that doesnt saw how much power your going for. I would go 9.7:1 comp. If you plan on going for insane power than 9.1. I daily drive my teg at 10.2:1 comp pushing just over 300whp.

 

500hp

 

cp 9.8.1 or 9.0.1? Wiseco was 9.7.1 but im using cp. just wanna make the best decision

 

i think i should be good with 9.8.1

 

its not quite that simple, hence why you cant just run super high compression on pump gas to match an even mild turbocharged 300whp. pressure created by the turbocharger can be cooled off before entering the combustion chamber as opposed to higher compression where there is no way to avoid an increase in temperature in the cylinder.

 

so i ordered the cp 81.5mm 9.0:1 manley rods this morning after calling a few tuner shops. Since its a street car it would be better im told.

 

So...you have 93 octane and are going to get a great tune. I would say something ~10:1. The only reason to go lower is if your goals exceed the ability of the tuner or if the fuel in the area is of a sub-par grade. You seem to have neither of those issues and should therefore go with something a little higher.

 

The issue is the efficiency of the intercooler, if it actually increases the density of air then yes you are correct, also keep in mind that a turbocharged engine runs hotter in general compared to a NA setup so the charged air can sometimes just offset the difference and your back to where you started. Tune of course has a lot to do with it but given tune is equal in both setups you will be surprised how close the EGG, ECT temps are of an off-shelf turbo kit compared to a all motor NA setup.

cheers