Eagle02

iTrader: (20)

Found a kit local for a good price on a 78mm kit and would like to drop it into my 2002 WS6.

I'm currently running forged rods and -4cc pistons on a stock crank, stock LS6 block with nitrous rings, gapped to mfg spec for a 200 shot.

I've got a set of ported polished 241s with ~61cc combustion chambers. Given a 6.0L gasket @ .054" I calc a CR of ~9.9.

Is that too high for say, 17lbs of boost? Or should I drop down to a set of 317s with a 71cc CC?

Finally, what about fuel system? I'm running a single 255 walbro intank through Lucas 42# injectors right now. Will I need more?

Thanks for any help folks.

Eagle02

iTrader: (20)

The 241s have been worked and flow 290cfm on the intake side and 204cfm on the exhaust... its the only reason I want to keep them

cjmatt

iTrader: (4)

better off selling the 241s and using a set of 317s. ported 241s can be sold for some decent cash, plus 9.9 is borderline too high for boosted applications.

317s will flow very well out of the box, plus boost is an equalizer to ported heads, you just up the boost a lb and it negates the effects of ported heads.

Ive got an extra set of 317s you could buy cheap, clean up and toss a set of springs on. My roommate goes to chicago every weekend to see his gf and could meet you if interested

Eagle02

iTrader: (20)

PM me on that, might be interested. How many miles on them?

XtremeDime

iTrader: (16)

Sell the 241s, pick up some 317s, bigger injectors and another walbro. Are you running pump gas? Were you going to use meth?

Eagle02

iTrader: (20)

I was aiming for 93, yes. Meth? Hadn't really considered it yet.

XtremeDime

iTrader: (16)

The lower the compression, the higher boost you can run on pump gas. Meth is always good, cheap insurance against detonation and it also drops IAT a good bit. You can probably do 17 psi @ about 9.3-5 CR on pump gas. Alot of comes down to tuning though, if you have a **** tune then it doesnt matter what your CR is.

Photochop

iTrader: (74)

This concerns me. You may wanna check with the piston manufacturer to verify that the nitrous gap is the same specification they give for blower/turbo applications with this piston/ring combo you're running.

Otherwise for fuel I'd hit up speedinc for some 60lb motoron's, pick up some of their budget rails, add a 2nd walbro to your intank assembly, and run the stock feed and plumb in a 6an return. You'll also need to remove the stock in tank fuel pressure regulator and pick up something like an aeromotive 6an boost referenced one.

A good tuner should be able to write up a good 3 bar speed density tune that will allow you to run up to 17psi or higher with that compression. You may want to consider a meth or meth/water mix to help maximize power at that boost level, as well as add some cheap octane/insurance.

LsxCody

iTrader: (3)

just keep the 241s,9.9 cr isnt too high for boost. you could still get away with running high boost. i would atleast run meth also

ZL1Killa

iTrader: (17)

as long as your rings/ringlands can take the boost, go for it.

Fuel wise, you will NEED a 2nd pump.
Lonnies performance has a great DUAL 255 setup that works wonderfully and it is worth the dough. You will have to send him your stock sending unit at first then he will send it back modified and it will be a complete bolt in kit.

cjmatt

iTrader: (4)

70k. they were on a friends truck, it ran fine. id clean em up though. kinda dirty and sat in the garage for a year or so. But youd need to upgrade the springs anyway if going turbo. Castings are good though. put in new valve seals, lap the valves and pop in springs and youll be all set. $150

Eagle02

iTrader: (20)

Lots of good feedback guys, keep it coming.

I do see quite a few people saying 9.99:1 CR is OK... which sounds good to me, but I'd rather not have to meth the car if I didn't have to.

Injectors and fuel pump... seems everyone is saying dual intank fuel pumps and 60# injectors. Fair enough. For duty cycle on the injectors, should there be more cushion allowed than the 90% mark for NA applications?

FPR... what pressure should I be aiming for @ WOT? I guess the return style is required when you go boost referenced FPR?

Which fuel rails should I use? Not looking for super expensive either...

Thanks again all!

Photochop

iTrader: (74)

I'd sell the 241s in favor of 317s, just to be on the safe side and aid in less compression.

With boost, more than enough fuel is crucial. You don't wanna run anywhere close to marginal. 60lb injectors are more than you'd need and fairly inexpensive ($380/set).

Base fuel pressure is debateable. You'd set your base fuel pressure at say 43psi, and your adjustable-boost referenced fuel pressure regulator would cause the fuel pressure to rise 1psi per psi increase in boost. So if you were boosting 17psi, your max fuel pressure would be 60psi based on a 43psi base idle pressure.

Like I mentioned, the speedinc budget fuel rail kit ($140ish for the kit) would be some to look into - used them on my last car.

Eagle02

iTrader: (20)

Speed inc is very close to me, I'll have to talk to Larry about the rails. Thanks for the heads up!

cjmatt

iTrader: (4)

yeah, id sell the ported heads just for the simple fact that ported heads are less necessary in boosted applications. you dont need to port heads so they suck more air as your forcing it in anyway...you can sell them for more than redoing a set of 317s also. allowing you to recoup some cash. you could probably pop off the springs from the 241s also if ya wanted