ProComp/Speedmaster aluminum heads

-
I’ll go a step further.....

On a suitable stroker short block, targeting at least 500hp, I would have no trouble taking a set of the cnc ported SM heads and crushing a set of the typical home ported 596’s.
 
PRH said:
I’ll go a step further.....

On a suitable stroker short block, targeting at least 500hp, I would have no trouble taking a set of the cnc ported SM heads and crushing a set of the typical home ported 596’s.
Click to expand...
I'm at 238-248@50 506-526 lift. I will likely need a cam change to see a serious change....
 
410 .010 flat tops with valve reliefs.
PRH said:
I’ll go a step further.....

On a suitable stroker short block, targeting at least 500hp, I would have no trouble taking a set of the cnc ported SM heads and crushing a set of the typical home ported 596’s.
Click to expand...
And what would your thoughts be doing that comparison using the non cnc-ported heads with what I understand to be a magnum Port? Which is supposed to be better?
 
j par said:
I assume you're referring to a member and I really hope he hasn't already chimed in on this thread and I can't remember?
Click to expand...
I have... Run the cnc ootb and commented on the thread. Lol ootb with the exception of changing the springs for my cam. Not a fan of the helicoiled rocker shaft stands, but honestly a more mild flat tappet setup may not have had my problems.
 
Nobody likes it when I refer to NHRA stock eliminator stuff....... but those things are excellent learning tools/examples on what’s important for getting good ET’s from mild stuff.

One of the best lessons is, the farther you stray from the race combo towards the street combo, the harder it is, or..... the more power you need to make...... to cover up the loss of overall efficiency of the car.

My friend races a 68 Firebird in Stock.
He’s always run a 400 in it.
A couple years ago he decided he wanted to build a 350 for it.
So, it’s a .060 over Pontiac 350, stock compression, the heads they use in 68(the only thing that’s legal) have 1.96 valves, and with a decent valve job they flow [email protected] lift..... which is the max lift allowed.
Stock iron manifold and Q-jet.
3320 race weight.

10.91@121 @2750ft DA
 
PRH said:
Nobody likes it when I refer to NHRA stock eliminator stuff....... but those things are excellent learning tools/examples on what’s important for getting good ET’s from mild stuff.

One of the best lessons is, the farther you stray from the race combo towards the street combo, the harder it is, or..... the more power you need to make...... to cover up the loss of overall efficiency of the car.

My friend races a 68 Firebird in Stock.
He’s always run a 400 in it.
A couple years ago he decided he wanted to build a 350 for it.
So, it’s a .060 over Pontiac 350, stock compression, the heads they use in 68(the only thing that’s legal) have 1.96 valves, and with a decent valve job they flow [email protected] lift..... which is the max lift allowed.
Stock iron manifold and Q-jet.
3320 race weight.

10.91@121 @2750ft DA
Click to expand...
How long is that valve held open at .420... LOL
 
And what would your thoughts be doing that comparison using the non cnc-ported heads
Click to expand...

If I were building it, I can’t imagine how the cnc heads wouldn’t make more power.
 
How long is that valve held open at .420...
Click to expand...

I’m not going to say, however it can be whatever you want, but no flycutting of the pistons is allowed.

I will say...... it’s probably less duration than you might think.

The 400 uses the same lift, but has heads with 2.11 intake valves.
It’s been 10.40’s@127+.

12526C0C-FEF0-4D94-82E4-DF2A65709BE6.png
 
PRH said:
I’m not going to say, however it can be whatever you want, but no flycutting of the pistons is allowed.

I will say...... it’s probably less duration than you might think.
Click to expand...
LOL..... I have a friend that went 11.3's in a full size dodge truck/360 in stock eliminator. Starts with 5k stall converter, 5.13 gears, and duration that only opens and closes the valve twice down the track... LOL But cast intake, TQ, and factory lift cam breathing through 1.88 valves :)
 
PRH said:
If I were building it, I can’t imagine how the cnc heads wouldn’t make more power.
Click to expand...
You made a reference in picking the CNC SM heads over the 596 s and I guess what I was asking is what was your thoughts over the unported SM heads over the 596's?
 
Personally since I'm aiming my car more for the street I would like to do more with horsepower than with adjusting my car...
 
318willrun said:
LOL..... I have a friend that went 11.3's in a full size dodge truck/360 in stock eliminator. Starts with 5k stall converter, 5.13 gears, and duration that only opens and closes the valve twice down the track... LOL But cast intake, TQ, and factory lift cam breathing through 1.88 valves :)
Click to expand...
Lol. "I have a friend"- that has a Chevy with a 3/4 cam....lol.....
 
It’s not that they make all kinds of power...... they don’t.
It’s about not wasting what you’re making.
Which is where the typical street/strip combo falls short.

It’s part of the compromise of the street use.

For street/strip stuff, I figure most combos are going waste 50-100hp..... so you need to overbuild by(at least)that much to reach the goal.
And it’s usually worse with a stick.

For a 3400lb street/strip combo with a stick and 3.5 gears...... trying to run consistent 11.9’s or better, I’d say it’s going to need an honest 500hp(std corrected flywheel)....... and have the car not be totally out to lunch....... or be racing in dog **** air.
Something like 60’ times in the mid-1.80’s....... speed about 115mph.
 
Toluene56 said:
I have... Run the cnc ootb and commented on the thread. Lol ootb with the exception of changing the springs for my cam. Not a fan of the helicoiled rocker shaft stands, but honestly a more mild flat tappet setup may not have had my problems.
Click to expand...
You currently run them? Do you run them on a stroker? Do you just Street Drive? Automatic or 4-speed?
 
PRH said:
It’s not that they make all kinds of power...... they don’t.
It’s about not wasting what you’re making.
Which is where the typical street/strip combo falls short.

It’s part of the compromise of the street use.

For street/strip stuff, I figure most combos are going waste 50-100hp..... so you need to overbuild by(at least)that much to reach the goal.
And it’s usually worse with a stick.

For a 3400lb street/strip combo with a stick and 3.5 gears...... trying to run consistent 11.9’s or better, I’d say it’s going to need an honest 500hp(std corrected flywheel)....... and have the car not be totally out to lunch....... or be racing in dog **** air.
Click to expand...
And that's exactly where I'm at. of course I'm at a average of a 12 V but have done it 12-3. I'd like to work off that 12/5 because that's seemingly a relatively easy number for my car to hit. Again I would like it to be pretty easily hitting the 11.9 and on a good day maybe a little better. So again I'm just looking for that little bit of extra horsepower, but also one of my big goals is again to drop the octane from about a 96. 5 down to 92...
All this being in the perfect world of not having to hook the car any harder than a 2.0-1.9 60 foot...
 
Well...... you have a plan.

You’ll just have to try it and see what happens.

One thing is for sure, nothing I say or think will have any affect on how your car actually runs.
 
PRH said:
Well...... you have a plan.

You’ll just have to try it and see what happens.

One thing is for sure, nothing I say or think will have any affect on how your car actually runs.
Click to expand...
I have a lot of ideas, but a plan....
 
PRH said:
Well...... you have a plan.

You’ll just have to try it and see what happens.

One thing is for sure, nothing I say or think will have any affect on how your car actually runs.
Click to expand...
Very, very true. 3 Components so critical and what I have lived by for years and years.
  1. Have a plan
  2. Try it and see
  3. Nothing said or written will have any affect on how the car actually runs.
 
The only way to really “learn” what does what..... is to try it yourself.
See if the way you think something is going to work out, actually does what you thought it would.
If it does..... great.
If it doesn’t...... try and figure out why not.
Learn from it either way..... and move on.
 
You must log in or register to reply here.
-

Back
Top