And very few have made over 500 HP fuel only with a HO pump. They just fizzle out between 485 and 495 rear wheel horse power.

 

It can definitely be done. The right combo usually goes to about 570HP.

But the SO pump is just so much easier!

The thing I don't like about the HO trucks is the higher compression ratio. So those going with higher HP, can benefit from a +.020" gasket.

Dave

 

dont be afraid of twins. they are better all around and can be done cheaper than a single charger.

 

Perfect discription. Took me 2 seconds, 235 SO. I would have never known to look there. Thanks Fishin2deep

 

I agree the higher compression isn't ideal for a max effort engine, but the mere .6 of a point or whatever it is isn't that big, imo.

Just run a hair less timing and that should basically be a wash.

 

AHHH! You said the magic words about compression!

You are talking static compression. And with the tight lobe centers and early valve closing events, dynamic compression DOES make a huge difference!

And pulling timing out of any engine further hurts it. Loss of bottom end and fuel economy to start.

And since we really can't finely control the timing yet, it's not a great option. The easiest thing is to lower compression slightly, keep the timing and allow that motor to spin!

Dave

 

Even better would be to give a proper cam that can USE that extra compression! Spread those centers already! Exhaust prob opens way too late, and intake closes way too soon.

Anyway, what the cam card for a stock ISB cam?

 

I have degreed a few stockers, but I don't have my notes. Probably tossed them. I had designed a few cam profiles but I lost interest.

Closing the intake later and spreading the lobe centers do help. Unfortunately, it often comes at the detriment of idle quality and some loss of low rpm torque. However, it can be made to work. It's tough to dial in the cams with a regrind as you start getting into the base circle to "make them right".

The best thing would be to start with a wide lobe blank and grind from there. And then produce off that cam. So we are just kinda stuck with the basic can profiles that are currently available. This is why most of the top racing/ pulling guys run low compression. There is only so much that can be done with the standard profile. And none of this goes into ramp profiles, opening/ closing rates, lobe width, tappet inertia and the list goes on and on. Just so much to consider when dealing with so much weight.

But again, dropping a touch of compression has huge gains. Especially with the SO pump. Typically, we look for more compression when we have a lower dynamic compression ratio. This recovers cylinder pressures, but usually at a higher RPM.

Dave

 

If you gave me a stock PN, I could pull the specs

 

I am sure I have a pile of them upstairs. But if I am gonna pull one down, I would just get the actual numbers. The advertised numbers were not even close on a few that I has checked.

Dave

 

I found the specs for a stock 24V cam.

LAME! The lift isn't on it, but 191 deg intake duration and 212 exhaust. Pretty tame.

107.75 LSA-- tighter than I expected.

 

Duration@.050
Intake 159
Exhaust 206

Lift:
Intake .235
Exhaust .297

LSA 107.5

Are the specs. I've seen floating around on the net.

 

From my '00 215hp 24v cam, lift on the intake is 0.234", exhaust is .293"