On a screw compressor, centrifugal and turbo, more boost is almost always better. Roots is a fine line and is very dependent on sc version, boost, heads, etc. Timing can have an effect on EGT's though, so sometimes you have to trade off.

With the 3.3, the odd side is .5 a/f leaner.

Thanks

Thanx for all the info Dustin, I am going to have to reread it again to fully understand what is in print.

I did have my builder weld in a nub for an oxi sensor before the water enters the tailpipes so we can fine tune this thing in the boat. he also tells me the same about the af ratios.

Question, if I don't change the pulley (don't think I will, the boat will be fast enough) I asume the engine is still strong and religable right? I mean I'm not hurting anything with these heads and lower boost right? I doubt it, just wanted to ask now that I have your ear.

We built 540's with AFR Alum. heads and ran the same Whipple package. With the port matching you did, and the better flow of the Dart heads, plus being Aluminum heads their is less restriction. Thats why you did all that was to make horsepower, you might as well take advantage of it. Just change the top pully that will get you 1.5 pounds of boost. Our motors were in a 35 Fountain, then a Black Thunder, and currently in another Black Thunder in North East Md. I know in the 100 hrs we put on them they never came apart, and the first Black Thunder owner, never took them apart. Probably close to 250 hrs thats with the smaller pully at 7lbs of boost. Im sure Dustin will answer you but if you do it now and get the motor propped right, you will be done. When you decide you want more power or someone goes by you then its back to testing props and that headache. Good luck have fun. Great boat, I have a good friend with a 572 ci. N/A in a 288 Sunny.

Not hurting anything, just leaving quite a bit of power on the table. Or, you could go the route of lower octane, I think your very close to being safe on 89 octane, it would be best to run a test on the dyno before the boat, but I'm pretty confident that if you take 2 deg's of timing out, she'll be a runner on 89 octane.

Thanks,
Dustin

CRAP, the engine was put in this week. So can I install a smaller pulley in the future without touching anything else? ie timing? If the timing does HAVE to be adjusted, it can be done in the boat right?

You can do it in the boat, but you move the entire curve, which is not so bad in most cases. Computer assumes it's set at 8deg in base timing mode. Therefore, when it says it's got 34deg, then it would really have 34. But if you turn base to 6, then it will still say 34, but will really only have 32. Same for advancing. Otherwise it needs to be done in computer calibration.

If the cal is correct, you can change pulley without changing ecm cal, but with the mods you already have, chances are that your gonna need to have the computer tweaked.

Dustin

K thanx, phuck it then, I'm very happy with how it is running right now. Idels like a champ when cold. Hope to water test this Sunday, rain or shine.

Thanx again for all your help Dustin, I understand this engine, and your product, ALOT more now.

naw Jeff 720 hp IS pretty facken bad.......tell you what.....I'll come up there and take it off your hands.....save you the pain.....

Maybe in a couple years when I'm ready for more boat. ;-)

haha what about the Apache....???