To get the highest HP on NA LSX running on methanol :

What is the best compression to run?

Dome or flat tops with small chamber ?

Stroker and displacement combo?

Will try to keep you posted as i go along.

Thanks.

 

Where are you located? What is the application?

You can run over 14.5:1 compression, but we set up most of our motors at 13.5 so that there is some decent life expectancy.

You are going to need a very small dome with a small chamber to reach that compression number, Wiseco has a shelf piston that might work out of the box, it's for a 4.0" stroke combination. I would want to see this on a big bore motor which means an after-market block too.

 

Bingo! Just to add: use at least 12.5:1 or it will be a dog.

Rich

 

Thanks to you all,

This setup is for drag race so if i go say 16:1 won't it make more power?

How about 4.125 bore and 4.125 stroke ?

Flat top piston is better than a dome and bigger chamber flows better

so which way should i go to make more compression?

 

In my fairly limited experience with NA alcohol, 14:1 seems to be a sweet spot, in general.

Rich

 

This is a ridiculous question unless you have a ton of disposable income.

800-900 horsepower isn't out of the question at all with an NA LSx, but it's going to come with a huge pricetag and will only be able to be attained by a very competent engine builder.

Something like a 427-454ci new LSX block with small chamber seriously worked C5R/LS7 heads, a $2500+ sheetmetal EFI intake manifold, and a 28x/29x @ .050" solid roller with .800-900" lift with a valvetrain that has the ability to spin 8000-8500 rpm.

Properly done, it'll set you back $25,000+... and that's just the motor

Mike

 

Eh, 800+ fwhp can be achieved with cathedral port heads at 427cid, with a sheetmetal intake, not quite that much duration, but around that much lift. You'll need 9000RPM though. It can be done on high octane gasoline. Change to square port heads and run alky will help things a bit more.

Check out what has been done by the School of Automotive Machinists. They/we were over 800hp back in 2003/4. In a recent magazine article, Judson said they were at 925hp with the C5R stuff.

 

Thanks eveybody,

to keep you posted i called to order my custom dome pistons

and was told to go with flat top and small chamber, may be better burn

and lighter weight.

Here is some of the parts on order:

ET LS7 heads with Titanium Valves - $4499

T&D Rocker Arms, Lightweight option - $1250.00

Custom Solid Roller Camshaft - $500.00
Rough specs are 274° to 276° in / 280° to 284° ex lift approx .750"

Pushrods - Trend 3/8" custom length - $200.00

Valve Covers - ETP aluminum - $300.00