700hp 540s
 

You guys with the 540s what rpm are you turning and at what compression ratio? How many hp are you getting?

5500...........9.1............630

5900, 9.5, 675

Friends 540's. 6000RPM, 9.25:1, 690HP.

Are those naturals Joe?

Let's hope mine are similar...... haha

yes...if they are the ones he told me about.

9.7 ratio 5,900 rpm 711hp

You also need to know if carbed or efi as well as if the dyno numbers are as dressed or dry headers without accessories.

I've sold the boat but:
540s from 500efis (using plenumber and mono blade TB)
9.75 cr
628 HP at 5,250 (needed more air to make more power)
699 TQ at roughly 4,300 (can't remember exactly)

The key here is these numbers were achieved pumping water in MY seawater pump, and out of MY CMI's by Mark boos at precision marine. The motors were dyno ed exactly as they sit in the boat.

Payupsucker yes they were. Dart 320 race series heads with some mild port work, bob madera solid roller, 1050 dominator carb.

9.8..........5700-5900rpm and 700hp, how much compression is to high? Do these numbers sound good?

Mer
 

MER Performance

4.500” x 4.250” 540 CID

9.6:1 CR

AFR 325 CNC Chamber_Hyd Roller

Correction factor_3.8% (1.038)

717.86 HP @ 5800

Mark commented the engine baseline dyno pull was ~685 and the additional 33 HP was found in the tune w/ the Holley EFI.

Bob

BB28

With a properly designed combustion chamber.9.8 on pump fuel is very doable.

Bob

Would that be with the Cnc afr chamber like we discussed?

Does that mean the combustion chamber needs to be cnc'd? How do you know if is properly designed? What octane pump gas are you talking.....89?

From talking to Bob, CNC is the way to go..

I guess a canfield 320 hard anodized is a great head because we run 10.3-1 and 0 issues on a bunch of 540's.:drink:

yup,everything is more likely to be the same size and volume.

No it does not need to be cnc'do what it means is you have a lot better chance of running higher compression with pump fuel with a combustion chambered designed today than 50 years ago. With the right chamber you can retard ignition timing therefore giving the motor less time to have a chance to detonate. The LS based motor / combustion chambers don't need much timing at all. If memory serves me when I had a conversation with a guy that specializes in LS motors (9 a week) he said because of the chamber design 21 degrees of timing is the sweet spot. 21 degrees of advance has alot less time to detonate than say 36 degrees (15 degrees to be exact). Hope this might shed some light on your question...

this off the ls forum.

Good safe place to start is 26 degrees at peak torque (4800 rpm) and ramping up to 28 degrees by 5600 rpm. You can then experiment with more timing or less. The 26/28 is very common for stock LS1 running 91-93 octane. Don't be surprised if your power doesn't change much with 2 degrees more or 2 degrees less timing. 26-28 degrees is the sweet spot for most stock motors.

The CNC ported chamber option helps low lift airflow substantially.

Our local cylinder head expert, stressed working the chambers on most BBC heads to me, years back. Guy is pretty sharp. Aside from the aid in low lift airflow, the swirl effect, and other tricks to aid in combustion efficiency were in his opinion, the best place to spend money on most bbc heads, aside from the valve pocket area, valve seat angles, and valve backcuts. He's old school, and has been porting bbc chambers for years, just doing it by hand the old fashioned way.

Myengine guy told me same stuff today also....

A few years back I took a set of aluminum Pontiac heads to Tommy Slawko. Told him to get what he could out of them. When I picked them up he never touched the ports he completely re-shaped the combustion chambers in the heads when he was done the chambers almost looked like a perfect heart shape. Just from doing the combustion chambers in the heads they picked up 30cfm. I asked him why he didn't touch the ports and he said they weren't worth porting if we wanted to get something out of them he would have to cut the heads up move the ports and weld them back together. There is a whole lot to a combustion chamber not just combustion it affects every stroke of the motor.