quote:

Originally posted by 1320racer:
Al, that's a big head for a bracket 565 but obviously worked well in your dragster. Shafiroff sells a similar combo

https://www.shafiroff.com/chev...-block-drag-race.php

Ed

Relatively speaking, dragsters are light cars and with the alky fuel and injection, low/mid range torque was not lacking. If you look at it from a HP/CID view point, 1.8 -1.85 is pretty typical on your professional engine builders for similar BBC engines built today as advertised with similar heads to the 383 HH's. And both intake manifolds and gas carb's have been improved since I had mine 565 which comes in at 1.81 HP/CID.

Agreed, good job

quote:

Originally posted by TOP38:

quote:

Originally posted by gxp7903:
Gas (X16) to Alky carb makes zero difference on my 632. BB3 heads. The only difference is the fuel bill is more expensive on X16, even with having to warm it up more on alky!

Not saying I don't believe you but without specific details I will say you have a choke point below the threshold of gas to alky fuels. With those cubes, the heads aren't big enough on alky so something else is the choke.

Well this has been back to back with a 1250 alky to 1250 gas. 1250 alky to a 1450 gas. And 1450 alky to 1450 gas. the 1450 alky at most was worth .01 over 1250 alky, if anything. the 1450s have 2.25 throttle bore. what area in my combo are you thinking is being chocked??

This is on a typical 1920 lb dragster running high 4.50s to the 1/8... Ive been 7.17 187 in 1/4 with 4.10s in rear, and 7.26 183 with 4.30 in rear.

Jeff do you need to stay with a short deck because of the hood/scoop combo? Do you need the weight of a steel block in the front? I would say either a 598 conventional head, aluminum block or a 598 sr20 with steel block.

Kenny he really just doesn’t want to part with the Benjamin’s in his pocket

quote:

Originally posted by gxp7903:

quote:

Originally posted by TOP38:

quote:

Originally posted by gxp7903:
Gas (X16) to Alky carb makes zero difference on my 632. BB3 heads. The only difference is the fuel bill is more expensive on X16, even with having to warm it up more on alky!

Not saying I don't believe you but without specific details I will say you have a choke point below the threshold of gas to alky fuels. With those cubes, the heads aren't big enough on alky so something else is the choke.

Well this has been back to back with a 1250 alky to 1250 gas. 1250 alky to a 1450 gas. And 1450 alky to 1450 gas. the 1450 alky at most was worth .01 over 1250 alky, if anything. the 1450s have 2.25 throttle bore. what area in my combo are you thinking is being chocked??

This is on a typical 1920 lb dragster running high 4.50s to the 1/8... Ive been 7.17 187 in 1/4 with 4.10s in rear, and 7.26 183 with 4.30 in rear.

When you put the 4.30's in, did you back to back the alky vs gas? Also the 4.30's certainly hurt performance due to added rpm.

Any 632 using conventional BBC's is over taxing the heads, they can not keep up with the air demand of those cubes, period! I don't care if you use Dart 355 heads or XYZ 380 heads or YYY 410's, the air/fuel still goes through the same size valve! So this limits both HP and rpm. If you try to spin it higher, you will lose performance. Adding alky to this combo just makes it worse since it occupies twice the space that gas does.

So assuming that your carbs used in your test are equal (big assumption & not talking CFM here), your results are due to the relatively low rpm you turn the motor which means the loss of HP on alky is offset by the added torque it provides.

[/QUOTE]

When you put the 4.30's in, did you back to back the alky vs gas? Also the 4.30's certainly hurt performance due to added rpm.

Any 632 using conventional BBC's is over taxing the heads, they can not keep up with the air demand of those cubes, period! I don't care if you use Dart 355 heads or XYZ 380 heads or YYY 410's, the air/fuel still goes through the same size valve! So this limits both HP and rpm. If you try to spin it higher, you will lose performance. Adding alky to this combo just makes it worse since it occupies twice the space that gas does.

So assuming that your carbs used in your test are equal (big assumption & not talking CFM here), your results are due to the relatively low rpm you turn the motor which means the loss of HP on alky is offset by the added torque it provides.[/QUOTE]

Not disagreeing with the thought about twice the amount of fuel in same space.. These heads are RFD 24-B, they have a 2.375 intake valve. So they are not stock bb3. I have never ran gas 1/4 mile. The reason I run the 4.30s is bc they are about 01 quicker to the 1/8 mile, and about everything is 1/8 mile now.
As for the RPM thing spinning it higher, when I was running the hughs converter, it went to 67-6800 in low gear, shifting at 7300, i raised shift to 7600 and it picked it up .01. I switched to a slack converter and put it back to 7300 and it ran the samething, its about 6500 in low gear. So how high are you referring to spinning it high loosing performance?

The 1450 carbs are both apd. 1250 alky (cast) was blp, 1250 gas (cast) was dale cubic. I also have tried a 1250 billet apd.
when switching gas to alky, RPM, 60ft, 330, 660, and mph were all the same. So what's that say.....

Our 565 conventional Pro-Filer head with alky carb will start it's 5th season in May, has about 420 runs on it now. Intake or oil pan has never been off. Oil samples are getting better not worse. Runs exactly the same ETs it ran when new.
Schaeffers 40wt oil, Rupert 1250 alky carb, check valves every 25-30 runs, Comp Cams bushed .904 lifters, don't take it above idle until it has reached 170 degrees and heat soaked for a while. Shift at 7200 and only a few 1/4 miles passes, mostly 1/8th. Same PAC valve springs for over 400 runs and are only down about 25 lbs on seat and around 50-75 open. Still well within spec.

The 565 seems to be a very easy combination to get 950 HP out of and it just keeps going.

Jok

quote:

Originally posted by Toad1:
Our 565 conventional Pro-Filer head with alky carb will start it's 5th season in May, has about 420 runs on it now. Intake or oil pan has never been off. Oil samples are getting better not worse. Runs exactly the same ETs it ran when new.
Schaeffers 40wt oil, Rupert 1250 alky carb, check valves every 25-30 runs, Comp Cams bushed .904 lifters, don't take it above idle until it has reached 170 degrees and heat soaked for a while. Shift at 7200 and only a few 1/4 miles passes, mostly 1/8th. Same PAC valve springs for over 400 runs and are only down about 25 lbs on seat and around 50-75 open. Still well within spec.

The 565 seems to be a very easy combination to get 950 HP out of and it just keeps going.

Jok

Jok

Not surprising at all. I can't say I wouldn't take a peek at it now though and if all looked good, which it likely will, I'd put new bearings & rings in it and keep going. When it does come time for springs, it's easy enough to do that on the car. Not saying you have to look at it now but you getting close to the cheap insurance time frame. 1/8 mile doesn't hurt either...

quote:

Originally posted by gxp7903:

quote:

Originally posted by TOP38:

quote:

Originally posted by gxp7903:
Gas (X16) to Alky carb makes zero difference on my 632. BB3 heads. The only difference is the fuel bill is more expensive on X16, even with having to warm it up more on alky!

Not saying I don't believe you but without specific details I will say you have a choke point below the threshold of gas to alky fuels. With those cubes, the heads aren't big enough on alky so something else is the choke.

Well this has been back to back with a 1250 alky to 1250 gas. 1250 alky to a 1450 gas. And 1450 alky to 1450 gas. the 1450 alky at most was worth .01 over 1250 alky, if anything. the 1450s have 2.25 throttle bore. what area in my combo are you thinking is being chocked??

This is on a typical 1920 lb dragster running high 4.50s to the 1/8... Ive been 7.17 187 in 1/4 with 4.10s in rear, and 7.26 183 with 4.30 in rear.

4.10 gears - 7.117 @ 187
4.30 gears - 7.26 @ 183

Looking at those numbers your motor is making anywhere from 1000 to 1060 HP! Big swing! Even using 1060, that's 1.67 HP/CID. My 10 plus year old 565 made 1.81 HP/CID which is 1144 w/a 632. Your combo is well short of that! Why? Answer that and you will have your answer why you don't see any difference swapping fuels.

A good 15 years ago we dyno'ed a friend 555 with a good gas and alky carb, both made 925 HP but the alky fuel made 50 FT-LBS more at peek torque BUT it did so at 500 rpm's less than the gas fuel. With the higher torque curve, the alky combo should be faster on the track if the converter is matched to the lower torque curve. This motor also was 1.67 HP/CID.

Your heads - are still too small to feed a 632, a 2.400" intake is too small! The airflow demand from this combo is way to great to be adequately feed from that valve size. Put that head on a 565 and it will make more HP/CID than on a 632. So your rpm limited by the head/induction systems capacity to feed the motor which limits the power you can make and alky fuel just adds to this problem. However at lower HP/CID numbers, as noted above with the 555 motor, your close to even. Go lower with this number and alky will be faster.

Why do you think motors stop making more HP as you increase RPM at some point?

quote:

Originally posted by 369dragster:
Jeff do you need to stay with a short deck because of the hood/scoop combo? Do you need the weight of a steel block in the front? I would say either a 598 conventional head, aluminum block or a 598 sr20 with steel block.

no I dont need to stay short deck and i really dont want the added weight of the aftermarket steel block I had a stock block before so the new blocks I would guess are much heavier.

quote:

Originally posted by TOP38:

4.10 gears - 7.117 @ 187
4.30 gears - 7.26 @ 183

Looking at those numbers your motor is making anywhere from 1000 to 1060 HP! Big swing! Even using 1060, that's 1.67 HP/CID. My 10 plus year old 565 made 1.81 HP/CID which is 1144 w/a 632. Your combo is well short of that! Why? Answer that and you will have your answer why you don't see any difference swapping fuels.

A good 15 years ago we dyno'ed a friend 555 with a good gas and alky carb, both made 925 HP but the alky fuel made 50 FT-LBS more at peek torque BUT it did so at 500 rpm's less than the gas fuel. With the higher torque curve, the alky combo should be faster on the track if the converter is matched to the lower torque curve. This motor also was 1.67 HP/CID.

Your heads - are still too small to feed a 632, a 2.400" intake is too small! The airflow demand from this combo is way to great to be adequately feed from that valve size. Put that head on a 565 and it will make more HP/CID than on a 632. So your rpm limited by the head/induction systems capacity to feed the motor which limits the power you can make and alky fuel just adds to this problem. However at lower HP/CID numbers, as noted above with the 555 motor, your close to even. Go lower with this number and alky will be faster.

Why do you think motors stop making more HP as you increase RPM at some point?[/QUOTE]

Sure my heads are probably to small. by your logic, when i had these exact heads on my 582 it should NOT have been .15 slower than what i am running now- while being 50 lbs lighter at the sametime. Good luck getting a head that flows more air like an sr20 or spread port on alky, and still make the same power.

I prefer not to race on dynos. The dyno does not show the true power when you can have a really loose one, which your 1144 sounds loose, or a tight one. Ive talked to multiple engine builders, some say its 1050, most say is 1150-1200.
What did yours do on the track when it was off the dyno? what weight?

All my original post said was I see no difference between fuels. A good sr20 615-632 runs 4.30s around here. and thats with an alum block, around 1800 lbs. give me an alum block, and im only .1 off that. I dont think thats to bad for a "small" head with a 632.

quote:

Originally posted by camaro77:

quote:

Originally posted by 369dragster:
Jeff do you need to stay with a short deck because of the hood/scoop combo? Do you need the weight of a steel block in the front? I would say either a 598 conventional head, aluminum block or a 598 sr20 with steel block.

no I dont need to stay short deck and i really dont want the added weight of the aftermarket steel block I had a stock block before so the new blocks I would guess are much heavier.

What kind of mph are you wanting to run on the stop? w
hat kind of ET off of the stop?
Those answers will direct you to the head/ci you should get, or even baby blower.
You did mention alky, id stay conventional if your set on alky.

Sure my heads are probably to small. by your logic, when i had these exact heads on my 582 it should NOT have been .15 slower than what i am running now- while being 50 lbs lighter at the sametime. Good luck getting a head that flows more air like an sr20 or spread port on alky, and still make the same power.

I prefer not to race on dynos. The dyno does not show the true power when you can have a really loose one, which your 1144 sounds loose, or a tight one. Ive talked to multiple engine builders, some say its 1050, most say is 1150-1200.
What did yours do on the track when it was off the dyno? what weight?

All my original post said was I see no difference between fuels. A good sr20 615-632 runs 4.30s around here. and thats with an alum block, around 1800 lbs. give me an alum block, and im only .1 off that. I dont think thats to bad for a "small" head with a 632.[/QUOTE]

OK, last time I will explain this to you. You clearly don't understand the ability to do work with respect to Torque & HP. Your 582 could have made the same HP as your 632 but it certainly did not make the same torque and therefore would be faster on the track. The 632 has more area under the HP curve therefore can do more work.

Dyno's do show what the motor is capable of and therefore what the potential performance would be in a given car. I did not say my 565 made 1144 HP, I said it made 1.81 HP/CID which simple math comes out to 1025HP. I also said that your combo based on your car's performance & weight shows 1060 max which is only 1.67 HP/CID. I also stated that if your 632 was as efficient as my 565 it would make 1144HP and one of the reasons it doesn't is due to the use of alky fuel vs gas in your combo! My car was 1925 lbs and ran 7.26 at 185 plus in good air over ten years ago.

No idea what engine builders you talked to about your motor making 1150 to 1200! It is not and can not.

And to be clear, I never stated that your combo was a dog! It performs as it should. Just as I never said your heads are too small, it's the intake valve that is!

So you never answered my question, why do motors stop making more HP once you get to a magical RPM? Once you understand this, you will understand the big picture.

This message has been edited. Last edited by: TOP38,

quote:

Originally posted by camaro77:

quote:

Originally posted by 369dragster:
Jeff do you need to stay with a short deck because of the hood/scoop combo? Do you need the weight of a steel block in the front? I would say either a 598 conventional head, aluminum block or a 598 sr20 with steel block.

no I dont need to stay short deck and i really dont want the added weight of the aftermarket steel block I had a stock block before so the new blocks I would guess are much heavier.

I would never try to make in the 1000hp range with a stock block. Will it work, maybe but it's something I wouldn't be comfortable with. Build either a 582 or 598 with conventional heads and you will be fast enough. I would give Joe at Sunset a call and get a price.

Camaro 77,

If you are trying to make 1000 hp, easiest way is to go low deck, 598, Dart Pro 2 380 heads, 800 to 850 lift, 288/300 at 0.050, 14:1 compression. Brodix HH's are a good choice too, i prefer the Dart heads. The pro 2 380s are quite a bit different than the Pro 1 series heads, put a 2.350" intake valve, they are a different casting and have more meat where they need it.

If you want more, move to a 20 degree head, more cam, more compression, these can make 1100 to 1200 on gas or alky. My 615, injected, 20 degree dart head motor makes 1090 hp 908 tq, runs 4.60 at 150 mph at 2000 lbs, 4 link dragster.

If you still want more you'll need a blower or a 20 degree setup with an aluminum block, or big chief style heads and tons of compression with lots of cam.