Dustin,

Quick question... Theoretically, if he has better flowing heads than stock wouldn't he make less boost and potentially more power with the same pulley since more air can get into the engine with less resistance? In the end he would make more power with less boost?

Then again...even if the heads flow better, now the cam would be limiting his power output?

Frank

Theoretically, yes, but he went to aluminum heads, which I'm all for, but they lower combustion temp and effictevely make less hp at the same cylinder pressure. But aluminum allows you to run more compression, via more air and fuel, which significatnly compensates for the difference in material. So if you have this motor at stock 8.75:1, then install Darts with the exact same combustion size (typically slightly larger), then the "rule of thumb" compression went down to nearly 7.75:1, yet you have the same airflow through the engine.

He said he has 5psi, the kits normally have 6.5-7psi so he lost 1-1.5psi from heads and port matching. The difference in power for the blower on 1-1.5psi is 3-5hp, so it's almost nothing in the way of restriction. Temp would only be effected 8-10deg F before the IC, after IC, it would be closer to 4-5deg F. Also, when lowering pressure on the inlet side of the valve, less air enters the cylinder. You need pressure to get the 02 in the cylinder.

Thats why I say go to 8psi, and 34 deg timing, or 9psi and 31 deg timing, it will past 800hp and somewhere near 850-875 trq. Right now it has 32deg timing and 5psi when stock, with cast irons, we ran 32 and 6.5psi.

Camshaft is really not much of a restriction at this level except for the 5600-6000rpm range. Ideally, with these heads, and a smaller pulley, I would go bigger, because you can safely run 6000rpm, and with the right cam, there is no question that another 30-50hp is in the motor. If it's all right, a 502ci, with Dart Pro1 heads, our stg2 kit, 8psi, 6000rpm should make 825-850hp on 91 octane fuel.

Thanks,
Dustin

Thanks for the insight Dustin, it's much appreciated!

What's total timing set at on the stage two kit. Or do you program them all differently. I asked the builder what he was running for total and he didn't know, only knew he set it at eight initial. The AFR's were well on the safe side running throught the stock CMI's but the chambers were on fire! and not in a good way :D. This is the first whipple motor I've worked on up here and it is truly an awesome kit!!

32Deg at anything over 5200rpm, 3psi+. Otherwise it's all over the place depending on manifold pressure and rpm.

If I know customer is running aluminum heads, I give it 2degs more timing normally.

Thanks,
Dustin

CHANGE PULLEY!! CHANGE PULLEY!! CHANGE PULLEY!! :D

Just teasing ya.

When you get it in the boat, I would recommend using a wide band AF, preferably from Innovative motorsports. Install on 1/3/5/7 side, at tailpipe, 2" away from flange to collector. Preferably on the side, not on bottom, water drips to the bottom. You'll want it to be 12:1 @ WOT above 5000rpm.

Thanks,
Dustin

Is this side leaner then the other side?

What is better, more boost or more timing? I am guessing and strickly a guess more boost and less timing produces more HP.

Thanks Dustin. Very good information

Great info...

It's extra nice when then man that builds the product is also a OSO member and will take the time to help a brother member. That's why Whipplechargers are top shelf and so is OSO!

this is awesome info for someone looking to do the same thing.
thanks everyone :evilb::cool-smiley-027: