Another "How much will it make?" Project "Special Needs"

[randy331]

Well,.. I haven't figured the port energy on the new heads.

I was hoping someone would say, well if it was me doing a second set of heads for SN with those goals, I'd make the MCSA a small amount larger and the overall average port CSA just a bit larger and have it flow enough to make the average port speed the same or faster (more cfm). Then work on making the port/intake combination flow better together. I'd want a mean flow curve from .400" lift or so up to .650" lift. That should help it at and after peak TQ rpm.

And I'd want that all accomplished with a smaller intake valve and throat with 50* seats in hopes that the added throat and widow DC will help TQ and HP/cfm numbers some and maybe the smaller window area will help protect the power down at the start of the pull.

Then I'd go on to a steeper ex seat. Say 52*-55* in hopes that will help power below peak TQ rpm and the 252* ex duration will still be enough with the steeper ex seats to not be a restriction at the top end.

Maybe add a bit of in. lift with a 1.7 intake rocker.

And I'd make sure the chambers are the same size or smaller to keep compression up.

A slightly thinner head gasket too if you can.

I'd think about testing a smaller tube header also. A 1 5/8 x 1 3/4 step may help the bottom without hurting the top. Maybe a smaller collector. Ex. can surprise you sometimes.

Then that big 4825 series Braswell and vacuum if you still don't have your 10 and 10 found.
Well,.. I'd try them anyway.

See,...those are kinda suggestions I was looking for.

Randy

[GARY C]

Maybe I should ask,.... what should the size / valve sizes / seat angles / flowZ be for the new SN heads ?

Randy

Whatever gives it the most Port Energy!!!

Rick

The real question is how well are these heads developed vs the original set?

EDIT, I posted this while you posted that.

[CGT]

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[randy331]

What are the flowz?

Flowz of
old heads.....New heads
200---123........128
.300---184.......185
.400---236.......237
.500---267.......273
.600---288.......296
.650---291.......300

Old heads 200cc,... new heads 208 cc.
Waitin on valves, springs, locators, etc and they will be ready.

Randy

[Carnut1]

Excellent flow #s for that sized port. I am betting you are well over 320ft/sec ave port velocity with very high port energy if you want to laugh at the term or not. I think they will make excellent power, Nice work!

[Carnut1]

The inake wing looks like it was added. If it was added what did you make the wing out of, how are you holding it in place and how did it change your flows? Thanks, Charlie

[randy331]

The inake wing looks like it was added. If it was added what did you make the wing out of, how are you holding it in place and how did it change your flows? Thanks, Charlie

The wing behind the guide boss is epoxy. I used an electric engraver on that area, then power washed them, then cleaned it with brake clean. Then I take the first bit of epoxy and smash it hard into the engraved surface before putting the full amount on I want.

As for flow, they add a bit of cfm. These are around 5-6. It calms the port to a little higher lift.

I'm a little concerned about rpm. I don't think these will peak at a lower rpm.

Maybe a dual plane?

Randy

[Carnut1]

The inake wing looks like it was added. If it was added what did you make the wing out of, how are you holding it in place and how did it change your flows? Thanks, Charlie

The wing behind the guide boss is epoxy. I used an electric engraver on that area, then power washed them, then cleaned it with brake clean. Then I take the first bit of epoxy and smash it hard into the engraved surface before putting the full amount on I want.

As for flow, they add a bit of cfm. These are around 5-6. It calms the port to a little higher lift.

I'm a little concerned about rpm. I don't think these will peak at a lower rpm.

Maybe a dual plane?

Randy

If you can get a dual plane to feed that high velocity port that might be a nice combo for the small cubes. I wouldn't be shy using a bigger carb as well. Bolt it all on the bench and you may be surprised. Dual planes are notorious for flowing much different port to port and upper H vs. Lower H. I think it would be a good experiment for this application. Thanks, Charlie

[randy331]

I'm sure it will be down on cfm on the bench vs a the single plane intake. It would probably be better on the dyno till 5000 rpm or so and then down above there, but it may surprise us.

I've given some thought to some epoxy in the single plane on the corners of the outside walls. Fill them in a bit and widen the radius. That'd probably help the bottom of the pull.

It will be interesting to see these vs the other heads on the same engine.

Randy

[Carnut1]

Last time I did this experiment was on a 275 cfm intake port with a well prepped dual plane it dipped to 247 cfm with a 770 cfm carb. I did not get to check against a single plane for that experiment just other dual planes. My best was a D.V. quadrajet copy that had tons of work. 253 cfm. I do think with a bit of work this combo will really haul the freight with a worked up dual plane and careful grinding. Thanks, Charlie

[GARY C]

This would actually be an interesting test to see.. Flow Bench #'s duel plane vs single plane compared to actual dyno #'s. I have a Edy Air Gap I can donate if Chad and Randy are interested.

[Carnut1]

I would love to see this test but be warned the dual plane needs a good amount of porting! Thanks, Charlie

[GARY C]

I would love to see this test but be warned the dual plane needs a good amount of porting! Thanks, Charlie

Even if the Air Gap flow #'s were in ported form the dyno #'s would be worth seeing vs a good single plane.

[randy331]

I would love to see this test but be warned the dual plane needs a good amount of porting! Thanks, Charlie

I've been involved in dual plane vs single plane dyno tests before and the duals are better down below 5000 or so.
They are better below peak TQ rpm and or move peak TQ rpm down some.

I just put a performer rpm I had done some porting on, on the new SN heads and it flowed 250 ish cfm at peak. I'm at mid 270s with the GMPP single plane on the same heads. The RPM intake doesn't fit the ports good, so it could be better as far as cfm.

Below peak TQ rpm more cfm isn't the restriction, but it'd be interesting to see if it'd pick up the peak TQ some and what it did to the overall power curve.

But,... I think Chad wants big peak HP numbers.

Randy

[CGT]

I would love to see this test but be warned the dual plane needs a good amount of porting! Thanks, Charlie

I've been involved in dual plane vs single plane dyno tests before and the duals are better down below 5000 or so.
They are better below peak TQ rpm and or move peak TQ rpm down some.

I just put a performer rpm I had done some porting on, on the new SN heads and it flowed 250 ish cfm at peak. I'm at mid 270s with the GMPP single plane on the same heads. The RPM intake doesn't fit the ports good, so it could be better as far as cfm.

Below peak TQ rpm more cfm isn't the restriction, but it'd be interesting to see if it'd pick up the peak TQ some and what it did to the overall power curve.

But,... I think Chad wants big peak HP numbers.

Randy

Not necessarily. I just know i want a single plane on the car.....for dumn reasons. I hate the way dual planes look!