BennAustralia

Hey Guys new Aussie to the forum here, ill give you a quick intro then see if you can help me out. The reason im asking here is I have been getting very conflicting opinions from workshops over here.

Note: I dont know much about engines, I just like driving them

So ive just bought a new car with an LS7 that the previous owner spent a load of money on and I know the history of the car, its in great condition so I got a great deal but want more power.

Engine Details:
LS7 7 Litre 427
bore x stroke 4.125" x 4.000"
Compression 11:1
Cast Ali block with 6 bolt cross bolted main caps
Crankshaft Forged Steel
Connecting Rods: Forged Titanium
Pistons: Hypereutectic
Aluminum Cylinder Heads: CNC Ported Aluminum LS7 style ports
Lingenfelter GT21 Camshaft
Isky Valve Springs
Titanium Retainers
Harrop HTV2300 (Rear Drive Pulley Kit) Supercharger
Running 6psi (IM TOLD BUT CANT CONFIRM, any ide how I can work this out?)
Power: 600rwhp

Goals:
I would like to be getting 700-800rwhp while keeping the engine very reliable, I plan to put a lot of miles on this, all street use.

Problems Ive been told I will face:
Detonation issues
Thin Cylinder walls

Possible solutions:
Run E85 fuel to reduce temp and possible detonation
Cylinder Sleeves

So guys what do you think on the following:
Can I get a reliable 700-800rwhp and remain reliable?
Is E85 a good solution to reduce detonation (I will run E85 either way)?
Are cylinder sleeves a good option?
Are these the best options, do you suggest anything else?
How much boost should I be running to keep things reliable?
What power numbers would you expect with your suggestions?

Cheers
Benn

KiwiKid

Hi Benn,

Bigger is better as in engine capacity, so you might want to think about re-sleeving your block with Darton's Ductile iron sleeves, as they will go out to 4.165" which will increase your cubic capacity to 435ci. It may not sound much but it will eliminate a weakness with the stock Ls7's thin sleeves etc.

The extra bore size will also help un-shroud the valves as well as increase the potential of the engine to carry more revs with a suitable cam change.

It all depends what you are willing to spend but, if you do decide to re-sleeve, and fit 4.165" forged pistons, then you could also go to a longer rod, like a 6.200" which will increase the engine's efficiency, as well as its reliability, by getting rid of the Hypereutectic cast pistons, which are "hand grenades" in my experience with these engines.

The world's your oyster, if you enough money to optimize the potential of the Ls7 engine.

Cheers,

Mark.

NAVYBLUE210

Agree with Kiwi on Sleeves for strength & Durability, Longer Rods, Pistons to drop Compression to 10:1 to run 12 PSI, with E85 should reach
750+ RWHP

KiwiKid

Hi Navy,

Good advice, strange that Benn, post's a question, gets two well meant responses and disappears.

I don't have any experience with forced induction Ls engines, but I am impressed with how much power potential they have even running comparatively little boost.

Cheers,

Mark.

redtan

iTrader: (5)

Depends on how much you want to spend also.

Simplest way is to get a bigger cam and E85, that should help get you close to your power goals while keeping reliabilty.

Next would be to add in some forged pistons which will lower compression and increase strength. With E85 there's no reason that a forged engine will not last at 7-800rwhp. The liners are thin but not that bad if you only plan on running 10psi.