ive done some research and now im trying to decide if the engine combo ive thought about would make good power and decent spool time.i have one question tho im waiting to here back from cp piston because i noticed the 9.7:1 comp pistons dont come in 81.5mm bore size? i figured to use a little higher compression because im going to be using a sc61.

reason why i want 81.5mm is room for error also that the cylinder walls wont be so thin. im shooting for around 400-425 wheel horse. i have a hondata s200 also

b16 head
supertech valvetrain
gsr cams
stock porting
victor mani
havent decided on tb yet
780cc injectors
aeromotive regulator
walbro 255

ls stock sleeves
eagle h beam rods
arp headstuds
i want cp 9.7:1 81.5mm but i dont know if they make them

sc61 with 63. ar exhaust housing v band
3inch turbo back exhaust
custom ramhorn header(my buddy is certified tig welder and went to school for fabricating)

im figuring that the sc61 wont have the best spool time but it is a fwd car and if you are getting full boost at say anything lower then 5000rpm your going to be burning tire everywhere.

 

i got off the phone with cp, they dont make that piston.... he did say that they are able to make custom pistons about $118 each. i was looking through there catolog and they make 81.5mm gsr pistons 9.8 compression. those would work in my setup up correct?

 

Those are the pistons you want!

 

the 9.8 comp gsr pistons? if so how do you think the rest of my build looks?

 

the compression ratio as long as your high 9's low 10's then it doesnt matter. you dont want anythign lower than a mid 9:1. the sc61 will do well but is a little over the top for 400whp. sc61 is a 600+hp turbo

57 or 60 trim with a .63 hotside is where you want to be with your setup. The gsr cam will make nice power with either choice and the .63 works well on a gsr cam. If you were going with a ctr/itr cam or something larger then i would say a .82 hotside and more rpms.

 

down the road i want to build a sleeved block and achieve more horse so i dont want to short myself by having to buy another turbo. i realize it will be a little laggy but when it does spool u will know it. another question what do you think would be a safe redline for this setup? the lower end will be balanced and blue printed.

john

 

you will be limited to the power production of the GSR cams but they should carry to 8500, rev till it stops making power.

 

A friend of mines gsr sc61 made 441whp with 81.5mm bore and stock sleeves with 9:1 pistons and stock cams and hit 10psi at 3800rpms

 

id like to see that boost plot

 

I made 512whp on my ls/vtec stock sleeves with a sc61. Yeah it took a while to spool but when it did it was amazing.

 

here is the dyno

 

ive seen builds with gsr cams making over 500hp how much quicker would the sc61 spool with itr or ctr cams? has anyone used this throttle body? http://www.go-autoworks-store.com/prprthbo.html

john

 

"spool" will not be "quicker" due to cams alone. This is where more stroke accompanied w/ bore comes into play. The cams help more with top end power. Think about it, you have 61mm inducer turbocharger on a sub-3.0 litre car. It's going to reach maximum pressure rather late in the rpm band (over 4500rpms). Deal with it..

 

so do you belive that i should go with a bigger bore? say i bored the block out to 83mm would it really make a noticeable difference?

 

don't go past ~82mm on stock sleeves.

 

im problay going to stay with 81.5, would .5mm even make a difference. and what do you guys think of that tb http://www.go-autoworks-store.com/prprthbo.html ? any1 ever have any expirence with it?

 

stick with 81.5mm running 81mm usually ends up in being a loose motor and very noisy, also not good for the piston skirts

 

What I'm saying is NO. a couple of mllimeters of bore isn't going to change anything. At that point you might as well stay 81.5mm or so. There's more to creating displacement w/ additional bore. Like I said, as a sub 3 litre engine displacement, maximum pressure will still not be reached until about 4500rpms with that turbocharger.

 

the reason you bore it out .5mm is because over time the cylinders go out of round and boring and honing it bring it to round.

 

i want to thank you all for the info everyone gave me. yea i didnt think it would really make a difference. another question the reason why i should go with pistons with compression higher to 10 is because the charger im going to use is bigger, and with higher comp pistons it will help it spool better? only reason why i ask is because ive seen alot of builds with comp about 9.1. correct me if im wrong

 

yea i would never build a engine without boring and honing it out at least 5mm over just for that reason.

 

lol. i hope you mean "0.5mm"

 

There's more to a turbocharged car than the turbocharger. The higher static compression helps with your acceleration rate OUTSIDE of positive boost pressure, since it will get to your effective compression a bit faster than at 9.0:1. The double side of that is to make sure that your tuning is done by a professional, and not just "a friend that knows how to change the numbers on the laptop".

 

dame shodan you know your ****!! no no no i wouldnt let somone i know tune my car unless they knew what there doing. i was planning on using gsr cams do you think that i should run a different set of cams such as itr or ctr?

 

Changing the cams out to ITR/CTR will net more power. If my goal was to make 400hp I would rather make it on say 15psi instead of 18psi. ITR cams will make it run more efficient thus make more power but like The Shodan said, it will not make much of a difference at all in spool. I picked up an SC61 as well but I've had a 60trim for the past 2 years and it made 425whp on pump gas which is more than enough for the street and 475whp on 112oct. The SC61 had been boxed up in a closet for almost 4 months now because I just love the power and spool of the 60trim. I just decided to slap on the SC61 because I want to go faster in the 1/4 mile otherwise the 60trim is perfect.