Bink

I'm planning a new engine for my '01 C5/Z06. Key word is -> planning.

Car is used recreationally on the street. Plan on doing some autocross (fun only) and track days.

Current LS6 engine is about 450 rwhp and 405 rwtq.

The new build I want to go with:

-4.125" bore (either resleeved LS2 - Katech shortblock or a Warhawk - Katech shortblock).
-12:1 Katech LS7 Pistons
-Ported LS7 heads and intake.
-Kooks 1 7/8" headers


4.00 stroke x 4.125 bore = 427
3.62xx stroke x 4.125 bore = 387
3.27xx stroke x 4.125 bore = 350


With the 3.27 stroke I can spin it to 8000 RPM - with the proper (light) valvetrain. Best to have a dry sump - I would lose my AC though. I won't give up the AC ..so, wet sump and I'll sacrifice HP at the top end.
Should be about 550 crank HP.

With the 3.62 or 4.00 stroke I can spin it safely to 7000 RPM. Crank HP should be in the 575 - 625 range, respectively. A bunch more torque than 3.27 stroke.

My question is which stroke would you go with??

Thanks for any and all suggestions!

John Shiels

8,000 rpm what manifold wil you use?

John Shiels

how about 402 with LS7 heads? I know someone making one now See how it turns out. 427 should be in the 600+ RWHP. What are the cost of each? Even if it doesn't matter to you just curious.

Falcon

Any idea what the torque curves are going to look like with the different engines?

Bink

Cost is critical, John - always.

From Katech thread:
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Quote:
Originally Posted by Katech
add $1000

Quote:
Originally Posted by Bink
Katech "Value 427" short block with Katech forged LS7 pistons, hardcoat anodized................................ ..$7230
Billet main Caps.........................$1000.
*********************Total $8230



Add $1000 and I have ******$9230

Value Sneak Attack 347
__________________


Here's a link to the thread on LS1Tech -> Jason from Katech on the 'Value' shortblocks.
Pricing on Katech's Warhawk blocks isn't up yet. --->http://www.ls1tech.com/forums/showth...1&page=4&pp=20

I figure the 427 completed Longblock with LS7 heads, LS7 Intake, cam, Timing set etc. about $14,000. The 350 "Sneak Attack add $1000.

Might be better off going with a new LS7 and have Katech rebush the wrist pins and replace the OEM pistons with their 12:1 forged slugs. SDPC has all the accessory LS7 dry sump parts available. I don't remember...does the LS7 have Billet main caps oem??

.....

Bink

Here's a link to the Value 427 with 3 different cams.





-->>>http://www.ls1tech.com/forums/showthread.php?t=571369


I think a shorter stroke will mean less torque for a given rpm, setup and cam.

Bink

Ported LS7.
Lingenfelter 100 mm MAF.
Hopefully I can get my hands on a Nick Williams' 100 mm TB.

John Shiels

Ported LS7 with what heads on a 350 what will fit?

Bink

350 is 4.125 bore with 3.2xx crank so LS7 heads will work.

AU N EGL

Joel

Talk to Jason. I think with an 8000 rpm range you may need a custom made intake manfold.

The LSx and FAST manifolds are really good for 4800 rpm tq max and 6300 rpm HP max, so any thing above 6500 may be waisted.

0Randy@DRM

I voted for the 4.00 inch stroke. Remember this is a 3000+ pound car. You will need a large amount of torque to pull it out of the corners. If you like 8000 rpm get a motorcycle or a honda.

Just my thoughts
Randy

Falcon

I agree with Randy. That horsepower is great, but you have to get to 7,500+ RPM's to get to it, while low end torque is just a throttle punch away. Remember, it's torque that puts you back in the seat.

What's the engine life of an engine that has to turn high RPM's vs one that turns less to develope power?

gpm30236

torque = would look for a nice fat torque curve


, desktop dyno pro , did a really good job predicting my numbers when i rebuilt the engine,. you could play with lots of variables. and see the effects. including things like changing degree of camshaft

XPC5R

With no rule restrictions, build the larger lower stressed motor any time you can. Components are cheaper, and wear and tear is reduced

Higher revs also mean running the gearbox at more revs - lower final drive - to get the poewr output at the wheelsm, which means more temp. to control there.

I'd suggest a crate LS7 - the keep popping up at around $13k. That gives the lighter rotating assembly (Ti rods) than the katech 427, and a lighter Ti valvetrain. Change cams, and play in the mid 500 rwhp range, with a functional dry sump setup and AC. Port the heads later when that feels weak, change cams, and get over 600rwhp.

The lighter assembly will accelerate faster, regardless of dyno output. The LS7 rods weigh approx. half of what after market steel rods do. You are saving 400g per rod, 3200g total - that's 7lbs of rotating assembly!

RAFTRACER

I can tell you from first hand experience that too much bottom end torque in an autox application is a very bad thing...........makes the car very knife edge and hard to drive, no one makes good enough tires to support that correctly at low vehicle speeds. I vote for the 3.622 crank Joel, but you already knew that

Additionally he forgot to mention that his car has a 4.10 rear gear ratio in it already......If you are going to go with large stroke crank and less RPM you better be changing that at the same time.

Bink

Tom -Good point, I've heard that too.
If the LS7 intake and 90 mm TB will support 7000 then I think 100mm TB and ported LS7 Intake might push 8000 rpm.

AU N EGL

I would not guess. I would ask someone. Dont want to waist time and money on a build that will not be optimal.

trumper Z06

I agree. Revving the hell... out of an engine & drive train....

reduces longevity!

At 13 large.... the technology included with the crate LS7 is tough to beat.

Cobra4B

^ Yes but the LS7 comes w/ the LS2 style reluctor wheel on the crank and is not compatible w/ the LS1 PCM. You have to tear down the motor and swap reluctor wheels to make it work.

Katech and SDPC will build you a sweet setup... I know SDPC was advertising wet sump LS7 builds for under $14,000 w/ everything you need for a running/functioning motor.

I agree that LS7 w/ a cam would be the way to go so long as you can find a cost effective way to run the motor... shoot my buddy Rich's z06 makes 490 w/ an air filter, headers w/ cats, and a corsa catback.

It's fast... very fast.

AU N EGL

Joel and I have both been talking to Katech about two slightly differnt engines.

An Katech LS2 427ci build up with high end parts, about 12-13G depeding on what one needs.

The Katech LS2 block is much stronger the the LS7 block and far better oiling. Note: Katech LS2 not GM LS2 block

Personally I dont think I want an LS7 at all, espeically for anything beyond DEs.