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Discussion Starter #1
I recently finished a build on a 11.5 to 1 572 (4.25 x 4.625). Engine was built by Jason Pettis and dyno'd at his shop.

Basic build:
BB-3 heads done by Darin Morgan. "Only" 2K worth of porting. Ti valves.
Gen 1 sniper, also done by Darin. Port matched and a little clean up.
Big oil pan
Nitrous pistons
4 vane Moroso pump
284 / 298. .851 lift on a 114
1150 Pro-systems

960 HP at 7200 rpms and 780 ish Ft lbs.

1.68 Hp per inch

I am tossing around the idea of a bigger engine in a couple of years. I know flow #'s are not everything. These heads "only" flow 442 cfm at .800

A 632 with the same HP per cu in. would come in around 1060.

Little more head and intake work "probably" worth 40 hp? 1100 Hp pump gas engine....all under the hood, pretty cool

Just bench racing a little..
 

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Should be able to do it with the right parts. You're not going to do it with those heads though, 632 or not. I know it's possible to make over 1000 on pump with the Sr20 heads on 598 cubes.
 

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I would imagine it should be fairly easy. I built a pump gas 598 for my drag boat that made 1000hp at 6500. It had out of the box 1800 Big Duke heads, tunnel ram with dual dominators, but it was all racing junk parts. Nothing special. It was 11.1, but in a jet boat with cool water, it would run just fine on 87 dock gas.

Anyone want to buy it? :p
 

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depends on what dyno you choose, ...
True, but the piece of nothing above was ran on one of our Superflows, constant .985cf and a friction table based off of our cup small blocks.
Wet sump, no depression pump, .780 lift roller, 80's ring pack 20-50 mineral ect.
I can't imagine with todays heads and some good parts, should be a shelf type item eh?!?
 

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At what point does "pump gas" not really matter? I mean, is the engine going to have a long enough service life for the difference in fuel costs to matter that much? Is it something that is going to be driven 3000 miles per year? If a person spends a ton of extra money to make a certain horsepower on pump gas, is it really going to get driven enough to make it worthwhile? Is avoiding the cheapest race gas or even Av-Gas worth 100+ horsepower? Av-Gas, especially with some Torco Accelerator (MMT) added, isn't bad stuff on a budget.

Good Luck!
 

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Limiting factor here will be the intake valve so whatever head will get you at least a 2.40 valve, and that's small for making peak power @ ~6500. With a 268 @ .05 intake lobe you're only looking at ~400cfm demand so the heads really don't need to flow a ton. They only need about 3.3"-3.4" min. area so I would try to find a set of small oval port spread port heads and run a 2.45 valve @ 90% throat and you can get away with a 45* valve job for longevity.
Tunnel ram with ~5.0 sq. in. runner entry would really help hit the 1K number.
JMO
 

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I have quite a few big effort pump gas engines that I do. The customers want to drive on the street and pull up to the pump for gas. Pretty simple... nothing more than that.
 

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Discussion Starter #12
I have quite a few big effort pump gas engines that I do. The customers want to drive on the street and pull up to the pump for gas. Pretty simple... nothing more than that.
Yup, that is it in my case. Also, if I ever get the car to Drag Week...I think pump gas is a requirement.

Scott, I am sure that different heads and a tunnel ram would certainly make more power, but I want to stick with the heads I have (ok with a little work done to them). Also, everything must fit under the hood.

John
 

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Yup, that is it in my case. Also, if I ever get the car to Drag Week...I think pump gas is a requirement.

Scott, I am sure that different heads and a tunnel ram would certainly make more power, but I want to stick with the heads I have (ok with a little work done to them). Also, everything must fit under the hood.

John
632 is a lot of cubes for those heads. The TR was "just sayin"...
I think I'd stick with the 4.25 stroke and just get really comprehensive with the build. Dry sump, big(dia.) cam and lifters, front drive dist, max out the heads and intake, get really detailed on internals and oil control etc.
 

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Just for comparison



571.207 Cubic Inches @ 7200 RPM with 107.00 % Volumetric Efficiency PerCent

Required Intake Flow between 414.4 CFM and 440.1 CFM at 28 Inches
Required Exhaust Flow between 289.4 CFM and 324.6 CFM at 28 Inches

600 RPM/Sec Dyno Test Lowest Low Average Best
Peak HorsePower 897.6 934.5 953.0 971.4
Peak Torque Lbs-Ft 723.7 753.5 768.4 783.2

HorsePower per CID 1.571 1.636 1.668 1.701
Torque per Cubic Inch 1.267 1.319 1.345 1.371

BMEP in psi 191.1 198.9 202.9 206.8
Carb CFM at 1.5 in Hg. 1273 1417 1488 1560

Target EGT= 1287 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
Octane (R+M)/2 Method = 102.9 to 104.3 Octane required range
Air Standard Efficiency = 62.90147 % for 11.500:1 Compression Ratio

Peak HorsePower calculated from Cylinder Head Flow CFM only
600 RPM/Sec Dyno Test Lowest Average Best Potential
Head Flow Peak HP = 855.2 958.0 1060.8



631.524 Cubic Inches @ 7200 RPM with 107.00 % Volumetric Efficiency PerCent

Required Intake Flow between 462.5 CFM and 491.8 CFM at 28 Inches
Required Exhaust Flow between 323.1 CFM and 362.3 CFM at 28 Inches

600 RPM/Sec Dyno Test Lowest Low Average Best
Peak HorsePower 1016.6 1058.4 1079.4 1100.3
Peak Torque Lbs-Ft 817.5 851.1 867.9 884.7

HorsePower per CID 1.610 1.676 1.709 1.742
Torque per Cubic Inch 1.294 1.348 1.374 1.401

BMEP in psi 195.2 203.2 207.2 211.3
Carb CFM at 1.5 in Hg. 1408 1566 1645 1725

Target EGT= 1287 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
Octane (R+M)/2 Method = 102.6 to 104.3 Octane required range
Air Standard Efficiency = 62.90147 % for 11.500:1 Compression Ratio

Peak HorsePower calculated from Cylinder Head Flow CFM only
600 RPM/Sec Dyno Test Lowest Average Best Potential
Head Flow Peak HP = 954.6 1069.3 1184.1


Ya, that's all you need is a little more head flow, little more lift and widen the LCA and you should be pretty close if the intake and carb can keep up.
 

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Discussion Starter #17
Just for comparison



571.207 Cubic Inches @ 7200 RPM with 107.00 % Volumetric Efficiency PerCent

Required Intake Flow between 414.4 CFM and 440.1 CFM at 28 Inches
Required Exhaust Flow between 289.4 CFM and 324.6 CFM at 28 Inches

600 RPM/Sec Dyno Test Lowest Low Average Best
Peak HorsePower 897.6 934.5 953.0 971.4
Peak Torque Lbs-Ft 723.7 753.5 768.4 783.2

HorsePower per CID 1.571 1.636 1.668 1.701
Torque per Cubic Inch 1.267 1.319 1.345 1.371

BMEP in psi 191.1 198.9 202.9 206.8
Carb CFM at 1.5 in Hg. 1273 1417 1488 1560

Target EGT= 1287 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
Octane (R+M)/2 Method = 102.9 to 104.3 Octane required range
Air Standard Efficiency = 62.90147 % for 11.500:1 Compression Ratio

Peak HorsePower calculated from Cylinder Head Flow CFM only
600 RPM/Sec Dyno Test Lowest Average Best Potential
Head Flow Peak HP = 855.2 958.0 1060.8



631.524 Cubic Inches @ 7200 RPM with 107.00 % Volumetric Efficiency PerCent

Required Intake Flow between 462.5 CFM and 491.8 CFM at 28 Inches
Required Exhaust Flow between 323.1 CFM and 362.3 CFM at 28 Inches

600 RPM/Sec Dyno Test Lowest Low Average Best
Peak HorsePower 1016.6 1058.4 1079.4 1100.3
Peak Torque Lbs-Ft 817.5 851.1 867.9 884.7

HorsePower per CID 1.610 1.676 1.709 1.742
Torque per Cubic Inch 1.294 1.348 1.374 1.401

BMEP in psi 195.2 203.2 207.2 211.3
Carb CFM at 1.5 in Hg. 1408 1566 1645 1725

Target EGT= 1287 degrees F at end of 4 second 600 RPM/Sec Dyno accel. test
Octane (R+M)/2 Method = 102.6 to 104.3 Octane required range
Air Standard Efficiency = 62.90147 % for 11.500:1 Compression Ratio

Peak HorsePower calculated from Cylinder Head Flow CFM only
600 RPM/Sec Dyno Test Lowest Average Best Potential
Head Flow Peak HP = 954.6 1069.3 1184.1


Ya, that's all you need is a little more head flow, little more lift and widen the LCA and you should be pretty close if the intake and carb can keep up.
Thanks....and very interesting. Your analysis is what I expected.

Scott; No doubt that would be the way to do it if I were willing to spent the money. Not that I am trying to be cheap....but like I said, sorta bench racing at this point. I need to get the car done and see how the current 572 lives on the street.. My real goal is a 6 second pass in a street legal nitrous car. I think I can go low 7's with the 572, but gotta get the car together and find out.

I am aware of Steve Barkers 632 (the Chevelle forum post) but his is with Big Chief heads. is RWHP numbers are IMPRESSIVE, for sure
 

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Just want to be sure you know how pipemax works, it figures HP/TQ on air flow/CR/VE/RPM, it does not use cam specs. So I just roughed in the 572's numbers and then adjusted the VE to fit your HP numbers, then changed the stroke to get the 632 numbers.

What I find interesting is that pipemax came up with CFM numbers close to what you said your heads flowed, so I would think the CFM numbers for the 632 is close to what you may need.

I don't have a clue if your heads can be made to flow close to those numbers, someone else will have to clue you in on that one.
 

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I recently finished a build on a 11.5 to 1 572 (4.25 x 4.625). Engine was built by Jason Pettis and dyno'd at his shop.

Basic build:
BB-3 heads done by Darin Morgan. "Only" 2K worth of porting. Ti valves.
Gen 1 sniper, also done by Darin. Port matched and a little clean up.
Big oil pan
Nitrous pistons
4 vane Moroso pump
284 / 298. .851 lift on a 114
1150 Pro-systems

960 HP at 7200 rpms and 780 ish Ft lbs.

1.68 Hp per inch

I am tossing around the idea of a bigger engine in a couple of years. I know flow #'s are not everything. These heads "only" flow 442 cfm at .800

A 632 with the same HP per cu in. would come in around 1060.

Little more head and intake work "probably" worth 40 hp? 1100 Hp pump gas engine....all under the hood, pretty cool

Just bench racing a little..
I am trying for a 1000 with pump gas right now. It's a 615 BBC with RFD heads and a Straub spec 55mm cam. Not going to the dyno...it's just not in the budget at this time. I look forward to seeing what your car does at that weight with pump gas.
 

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I recently finished a build on a 11.5 to 1 572 (4.25 x 4.625). Engine was built by Jason Pettis and dyno'd at his shop.

Basic build:
BB-3 heads done by Darin Morgan. "Only" 2K worth of porting. Ti valves.
Gen 1 sniper, also done by Darin. Port matched and a little clean up.
Big oil pan
Nitrous pistons
4 vane Moroso pump
284 / 298. .851 lift on a 114
1150 Pro-systems

960 HP at 7200 rpms and 780 ish Ft lbs.

1.68 Hp per inch

I am tossing around the idea of a bigger engine in a couple of years. I know flow #'s are not everything. These heads "only" flow 442 cfm at .800

A 632 with the same HP per cu in. would come in around 1060.

Little more head and intake work "probably" worth 40 hp? 1100 Hp pump gas engine....all under the hood, pretty cool

Just bench racing a little..

Was this on pump or race gas?
 
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