before/after 383 dyno results

[ClassAct]

You have a problem with blanket statements?

Yet you said low lift flow is always good..

Let's see one of your engine builds that proves it? A before and after would be good

Flow is good. When someone goes to buy a better cylinder head for their engine, do they look at it and say, "Well, this head has more low lift flow than my stock head, must be garbage then!". No, people swap to cylinder heads that have better low lift flow and gain power ALL THE TIME. The heads also have better high lift flow! How come they don't cancel out and gain zero power?

You are making a change that happened to decrease low lift flow, and your conclusion is to say that low lift flow is bad. Instead, you should be investigating what else changed when you decreased low lift flow. We have thousands upon thousands of available dyno tests, magazine articles, and OEM test data that shows a better flowing system makes more power (within reason).

Maybe the dynamic flow improved, but obviously a flow bench doesn't show that. In an engine the valves are opening and closing, it's not a static flow condition like a flow bench. It's possible that, under the conditions the engine is running at, you improved flow and don't even know it. This does not mean low lift flow is bad, it just means the way people are measuring low lift flow is bad. You have to be more specific and get to the root of the issue.

I'd share some data if I could, but the NDAs I work under are pretty ironclad. Take that as you will.

You answered your own problem. If you reduce low lift flow, you have to know WHY you are doing it. I know why I do it. In fact, I don't really care what the actual flow number are. They make little difference in the actual power of the engine.

It's how you use a flowbench that counts. Every single time I've used steeper that 45 degree seats clear up to 55 degrees I've made more power. Every time. That's N/A, blown alcohol, nitrous, several turbo combos and a bunch of circle track stuff. There is more to cylinder heads than flow at 28 inches.

Again, a reduction in low lift flow is the least of my concern. If I use a steeper than 45 degree seat and lose flow, even lose flow to max lift, I do not care. I care about the end result.

[randy331]

Well, got the short block together on this 383. Takes 15-16 Lbs to rotate it over.
I'd like that to be less, but it's still 1/16 1/16 3/16 ring pac.
The owner is up for a custom pan too now.
He's askin about trying a 4500 series 1050 on it when it's back on the dyno.

Lookin like compression is still gonna be right at 13-1. Wasn't wantin it any higher.


Not sure how soon I'll have it back on the dyno.
Got my son's 505 Cube engine for his truck he tows with sittin here ready to go to the dyno, and
got a BBC pullin truck engine ready to go as soon as he brings the motor plate up so i can get the vacuum pump fitted up on it.
Tryin to keep the thread up dated.


Randy

[frankthetank]

Appreciate you guys sharing, I mostly lurk and learn on this forum. Cant wait to see the 383 results.

Care to share any details on the 505 truck build, maybe a separate thread I guess...?

Been looking at older gas duallies but the motors generally are ho hum until the 8.1l, and those are hard to find.

Sorry for the sidetrack...

Thanks,

Frank

[randy331]

Care to share any details on the 505 truck build, maybe a separate thread I guess...?

The 505 in named Overkills, it's 4.350 bore x 4.25" stroke. Has a set of ported BB1 heads on it, ported dual plane intake, forged flat top pistons, 1/16- 1/16-3/16 rings,. 9-1 compression, has a coustom solid roller in it. Bigger than I'd have used cause he wanted some sound. 650 Quick fuel carb. 1.72 ratio magnum rockers.
It should run good. May be a little hard on the fuel bills. LOL
We've ran it here in the shop, but he wants it on the dyno before it goes in the truck.

Randy

[racinnut15xm]

Appreciate the update randy. Our modified stuff is all track 1, wish you wouldn't of welded/ported them to see what a valve job and all the rest would of done as ours have spec heads. But still following along.

[PRH]

Appreciate the update randy. Our modified stuff is all track 1, wish you wouldn't of welded/ported them to see what a valve job and all the rest would of done as ours have spec heads. But still following along.

Are those motors using actual “track 1” heads, or the spec heads that have the “spec” cast into the runners?
The SPEC heads have cnc’d chambers........ is that how Track 1’s come?(I haven’t done anything on a set of Track 1’s in ages.....I can’t remember if the chambers were cnc’d or as cast)

Through the years I’ve freshened quite a few sets of the SPEC heads, and I’ve flow tested a number of them too.
For something that supposed to be part of a solution to equalizing the performance between competitors........ I’ve seen a pretty big variance in what they flow, although I’ll also say it seems the variances have lessened in recent years.

[racinnut15xm]

Appreciate the update randy. Our modified stuff is all track 1, wish you wouldn't of welded/ported them to see what a valve job and all the rest would of done as ours have spec heads. But still following along.

Are those motors using actual “track 1” heads, or the spec heads that have the “spec” cast into the runners?
The SPEC heads have cnc’d chambers........ is that how Track 1’s come?(I haven’t done anything on a set of Track 1’s in ages.....I can’t remember if the chambers were cnc’d or as cast)

Through the years I’ve freshened quite a few sets of the SPEC heads, and I’ve flow tested a number of them too.
For something that supposed to be part of a solution to equalizing the performance between competitors........ I’ve seen a pretty big variance in what they flow, although I’ll also say it seems the variances have lessened in recent years.

Different sanctions have different chambers. Usra/usmts has cnc chambers and are angle plug, the IMCA spec that the late models run I've had were a cast chamber. 2brl sprints around here run the same casting as imca its straight plug and cast chambers. And they all have a Spec cast into the runners. They are based on a track one casting.

[randy331]

I was just running your flows through Rick's Curtain area program, very pronounced increase in window DC at all lifts.

Is an increase in window DC always good ?
No limit to it ?
What else will you trade for an increase in window DC ?

Randy

[ClassAct]

I was just running your flows through Rick's Curtain area program, very pronounced increase in window DC at all lifts.

Is an increase in window DC always good ?
No limit to it ?
What else will you trade for an increase in window DC ?

Randy

And we're off!!!!!! I'd love to hear the answers to the questions you ask.

[steve316]

there may be a lot of answers but are they the right one?

[CGT]

I was just running your flows through Rick's Curtain area program, very pronounced increase in window DC at all lifts.

Is an increase in window DC always good ?
No limit to it ?
What else will you trade for an increase in window DC ?

Randy

More bowl?????‍♀️

Valve limited or port limited or valve timing limited applications?

Seems like in some of those instances an engine may respond to maybe a larger valve and corresponding window even if the rate or efficiency was less.

[PRH]

The SPEC heads I’ve done are all angle plug with cnc’d chamber...... and as from Brodix I’ve seen them as bad as:

2.055/1.60, back cut on both valves, 4.00 bore, no tube on ex
Lift——— in/ex
.100—— 64/51
.200——130/114
.300——187/156
.400——232/172
.500——243/174
.600——255/179
.700——255/181

That’s with the Brodix radius valve job on both seats.

I’ve also had them flow just over 270 ootb with the same VJ.

[steve cowan]

The SPEC heads I’ve done are all angle plug with cnc’d chamber...... and as from Brodix I’ve seen them as bad as:

2.055/1.60, back cut on both valves, 4.00 bore, no tube on ex
Lift——— in/ex
.100—— 64/51
.200——130/114
.300——187/156
.400——232/172
.500——243/174
.600——255/179
.700——255/181

That’s with the Brodix radius valve job on both seats.

I’ve also had them flow just over 270 ootb with the same VJ.

Why would they do this sort of valve job when they must know it not the normal,
Surly a 45 deg 3 angle VJ would outway a radius on the intake and produce a better product out of the box??

[zums]

I was just running your flows through Rick's Curtain area program, very pronounced increase in window DC at all lifts.

Is an increase in window DC always good ?
No limit to it ?
What else will you trade for an increase in window DC ?

Randy

Different upper rpm points could make those questions moving targets
Tom

[PRH]

The SPEC heads I’ve done are all angle plug with cnc’d chamber...... and as from Brodix I’ve seen them as bad as:

2.055/1.60, back cut on both valves, 4.00 bore, no tube on ex
Lift——— in/ex
.100—— 64/51
.200——130/114
.300——187/156
.400——232/172
.500——243/174
.600——255/179
.700——255/181

That’s with the Brodix radius valve job on both seats.

I’ve also had them flow just over 270 ootb with the same VJ.

Why would they do this sort of valve job when they must know it not the normal,
Surly a 45 deg 3 angle VJ would outway a radius on the intake and produce a better product out of the box??

You’d have to ask that question to Brodix..... and Edelbrock.
To the best of my recollection, all of the E-Street or RPM heads I’ve had in the shop have always had a radiused intake seat.