Built ls1

[M01ST]

Hey guys need some info please.

Plan is to build a high compression motor and run e85.
I have a victor jnr manifold plus throttle body and will be running a 232/234 112lsa .598 cam, underdrive pulleys, double row chain, 241 heads ported and all the valve train gear already done. Where I need help is what Pistons and rings to run. Should I flycut or should I run domed Pistons with valve reliefs? And what brands do people recommend.

Cheers guys

 

[enroh]

To make the most of e85 on a naturo motor is be running a much more aggressive cam then a run of the mill comp 284xer. Your best bet is talk to an engine builder and he will work out what pistons rings etc to use. Are you going to spray it?

 

[M01ST]

Spray what? Was just gunna build it all in my shed myself. What size cam do you reccomend.

 

[Simon by sv8 ls1]

Hey did this high compression build get done?

 

[monstar]

Hey did this high compression build get done?

I did a high compression LS build FWIW.

 

[Simon by sv8 ls1]

I did a high compression LS build FWIW.[/QUOTE
Did you make a thread ?

 

[monstar]

Info here, some pics to and discussion in comments, happy to help.
More related stuff

 

[monstar]

hey mate! Big fan of the high comp ls you have do you think it would be safe with something similar in a ls1 staying 346ci on e85?

Well depends on how high you are safely prepared to go and how you intend to use the car because the older ECU isn't up to the ultimate job, but alcohol and high CR is better than stock.
My build is an L77 with an e38 twin 32 bit PowerPC ECU so it has the brainpower to utilise a fuel composition sensor to inform tune in real time and a cam phaser to alter valve events, so it can run good whether 98 or e100.
This is where I got a lot of info from, not all relevant but worth covering the basics first coz I don't know your level of experience is all.
Here is the spreadsheet mentioned on that page that you use to calculate the effective (dynamic) compression ratio.
With the spreadsheet calcs and notes you quickly discover static or nominal compression(CRn) despite being the most bandied about ratio is too basic and almost meaningless, that the key to the build is effective compression ratio (CRe).
CRe is the first determinant whether you can safely run on pump petrol, part ethanol or e85. Then there is mechanical octane - squish / quench, chamber dynamics. Then there is the usual like IAT, plug heat, etc.
As I see it you can use the older ECU but everything must be tuned to one fuel fraction - e85. Is that what you intended?

 

[monstar]

Plug in head chamber volume and rod length and stroke to the above calculator and it will fill in the gaps re design geometry. You want to keep same cubes so the first thing is whether engine out swap pistons or shave the shit out of the heads and deck the block.
Best approach is don’t shave heads so to leave contours of the chamber vs a flat head. You need the curves of the LS heart shaped box there for swirl, tumble, and other real estate for squish / quench.
I’m assuming you are going with e85 fuel fraction, which means no practical upper knock limit, so you will want the smallest possible chamber via domed, forged, lightweight relieved pistons and maybe shave some deck height to get high squish.
All that's about CRn, static compression. The second thing to consider is how you are going to use the motor, as in fit for purpose driving daily for starting and reliability and of course the spread of torque curve / power delivery hence cam spec. specifically piston position vs Intake Valve Close (IVC).

Called A on the above spreadsheet = crankshaft angle in degrees ABDC from 00 to 900. BTW that is actual seating spec, @ 0.006" on a cam sheet not the @ 0.050".
Although the LS1/LS2/LS6 cathedral-port versions are different, not as developed for anti-knock combustion efficiency, this article helped me with acceptable CRe range for GenIV 821 heads, generally accepted stock GenIV rectangle ports are up to 9.0 CRe with 98.

Here is the spreadsheet mentioned in post #28 that lists the CRe for a given IVC.
FYI different terms on this sheet:
CRn = SCR
CRe = dynamic CR
IVC = theta
My IVC @ 66.0º ABDC with CRn of 13.47 = CRe of 10.56:1. That is too high for gasoline, propane, only alcohols.
My IVC @ 79.5º ABDC with CRn of 13.47 = CRe of 9.288:1. That is 'workable' with 821 heads and high squish (mechanical octane) on pump gasoline.

 

[DLFHUB666]

Shiver me timbers! The old seadog has returned, Hoist the Jolly Rodger and prepare for battle. AAAAAAAARRRRRRRRGGGGGGHHHHHHHHHH!!!!!!!!!!!!!!!