#161  
Old 02-22-2020, 01:04 PM
F/S GTO F/S GTO is offline
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Wrap your head around this. My 350 HO shows 450 hp on the Moroso speed power calculator. The heads flow 200 c.f.m . Of course that's Stock and not SS. My head was the one poured by NHRA for the spec on their website for the 18 head.

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Old 02-22-2020, 01:25 PM
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Originally Posted by F/S GTO View Post
Wrap your head around this. My 350 HO shows 450 hp on the Moroso speed power calculator. The heads flow 200 c.f.m . Of course that's Stock and not SS. My head was the one poured by NHRA for the spec on their website for the 18 head.
If you don't mind. At what RPM are you shifting at?

Thanks,
Stan

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  #163  
Old 02-22-2020, 01:57 PM
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Shifting @ 6300 cross the finish line @ 6900. Haven't had it on the dyno yet so I don't know where it peaks. Hope to do that this summer.

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Old 02-22-2020, 01:58 PM
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Quote:
Originally Posted by F/S GTO View Post
Wrap your head around this. My 350 HO shows 450 hp on the Moroso speed power calculator. The heads flow 200 c.f.m . Of course that's Stock and not SS. My head was the one poured by NHRA for the spec on their website for the 18 head.
Yeah, that's interesting.

If I remember correctly, he ran high 10's with that engine, in his '68 Bird.

I wonder how much power is possible with that same 200cfm flow, for a 400, a 428, or a 455 engine, with the correct cam for head flow & engine used ?

Also the heads used on the larger 4-barrel engines would have bigger valves, or at least bigger intake valves.

I'm just ASSUMING that if those heads would make 450hp, on a 350, with a low lift Stocker cam, they would have to make more than 450hp on a larger cube engine, with a bigger cam, wouldn't they ? OR, would the 200cfm flow actually limit the power of the larger cube engines, so that they couldn't make any more power than the 350 ?

I have all these questions because I really don't have a clue. Exactly how much torque & hp can be made with a 400, 428, & 455 engine, with heads that flow 200cfm, 210cfm, 220 cfm. I'd love to have the money to do all the dyno testing to find out, for sure.

Anybody here have a Pontiac engine that made over 450hp, with unported D-port iron heads ? Not counting the Stock Elim cars.

Len Williams estimates that his 6X head 455 will make aprox 425hp. That's with unported heads, and at aprox 9.25 pump gas CR. It has Rhoads lifters & what i assume is probably an 041 clone cam, like maybe a Melling SPC-8.

http://lenwilliamsautomachine.com/455_Long_Block.html

If that estimate is pretty close, then, with the correct drag only cam, it should easily make over 450hp. How much over, I don't know.


Last edited by ponyakr; 02-22-2020 at 02:23 PM.
  #165  
Old 02-22-2020, 02:07 PM
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Shifting @ 6300 cross the finish line @ 6900. Haven't had it on the dyno yet so I don't know where it peaks. Hope to do that this summer.
Thank you. Would you mind posting a time slip and telling us the min you and your need to weight? Also based on your F/S I take it you are running a manual trans.

Stan

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  #166  
Old 02-22-2020, 02:09 PM
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My 400 heads flow more than that.

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Old 02-22-2020, 02:17 PM
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Yes, it's a stick car. The minimum weight is 3220 but I can only get it down to 3300,so I'm 80 lbs heavy for E/S. Here's the best run last year. Going to try another set of headers and I found something in the oil pan so I'm hoping for a little more this year.
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  #168  
Old 02-22-2020, 03:15 PM
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Found his chart compiled by Air Flow Research.

It says that 200cfm flow will only support 411.4 hp,

and that 250cfm flow will support 514.3 hp.

https://www.hotrod.com/articles/airf...ylinder-power/

Don't have a clue how this might apply to Pontiac engines, or if it would, at all.

Another rule of thumb, ball park, figure I saw posted was that hp potential is aprox 2 times the flow. So 200cfm flow would support 400hp. 250cfm flow would support 500hp.

Many say an engine is just a air pump. So, power potential depends on how much air you can pump thru it.

But, all this doesn't answer all my specific questions about the power potential of the particular Pontiac engines in question, in legal SS form. Most, or at east many of those may never be answered. But, at least I'm searchin for the answers.


Last edited by ponyakr; 02-22-2020 at 03:30 PM.
  #169  
Old 02-22-2020, 03:39 PM
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Originally Posted by F/S GTO View Post
Yes, it's a stick car. The minimum weight is 3220 but I can only get it down to 3300,so I'm 80 lbs heavy for E/S. Here's the best run last year. Going to try another set of headers and I found something in the oil pan so I'm hoping for a little more this year.
First let me say thank you again for willing to share your information. If I my ask did you build this combination because you basically had the parts for it or you looked at different combinations in the guide and decided this was the best one?

Stan

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  #170  
Old 02-22-2020, 04:02 PM
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Someone got NHRA to take 15 hp of the 350 back in 2008. I thought it would be fun to try something nobody had really run before. It's fun motor with the 4 sp. I ran it with the 400 headers so this year I'm going to have some built just for the 350 and go to the dyno. Hoping for another tenth out of it,it'll never run as fast as the 350 Chevys in the same class,they're rated at 295 hp. Someone else is building one but it's going to be an automatic car.

Most of the time I run the 400.

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Old 02-22-2020, 05:35 PM
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Originally Posted by F/S GTO View Post
Someone got NHRA to take 15 hp of the 350 back in 2008. I thought it would be fun to try something nobody had really run before. It's fun motor with the 4 sp. I ran it with the 400 headers so this year I'm going to have some built just for the 350 and go to the dyno. Hoping for another tenth out of it,it'll never run as fast as the 350 Chevys in the same class,they're rated at 295 hp. Someone else is building one but it's going to be an automatic car.

Most of the time I run the 400.
Nice. So he was able to drop about 150 pound?

Stan

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  #172  
Old 02-22-2020, 06:03 PM
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Plus, SS rules allow a max of 4.229 stroke. So, the 4.25 stroke would be legal.
Umm, what???


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Old 02-22-2020, 06:11 PM
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Umm, what???

I saw that. Just figured with how old I am that was this new math I keep hearing about.

Stan

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  #174  
Old 02-22-2020, 06:33 PM
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Umm, what???

VERY funny guys ! 1st mistake I ever made.

Let's see 4.250 - 4.229 = .021

Is that correct ?

Just out of curiosity, how much less power would the .021 shorter stroke engine make than the longer stroke engine ?

Another way to say it is: How much of a power difference would that .021 stroke difference make ? Ya'll have any computer programs or rule of thumb calculations to figure that ?

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Old 02-23-2020, 01:07 AM
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Originally Posted by ponyakr View Post
Found his chart compiled by Air Flow Research.

It says that 200cfm flow will only support 411.4 hp,

and that 250cfm flow will support 514.3 hp.


https://www.hotrod.com/articles/airf...ylinder-power/

Don't have a clue how this might apply to Pontiac engines, or if it would, at all.

Another rule of thumb, ball park, figure I saw posted was that hp potential is aprox 2 times the flow. So 200cfm flow would support 400hp. 250cfm flow would support 500hp.

Many say an engine is just a air pump. So, power potential depends on how much air you can pump thru it.

But, all this doesn't answer all my specific questions about the power potential of the particular Pontiac engines in question, in legal SS form. Most, or at east many of those may never be answered. But, at least I'm searchin for the answers.
Quote:
Actually reaching the predicted power level requires maximum compression, the right cam, a tuned exhaust system, and a nonrestrictive carb and intake manifold. The combined lift generated by the cam lobe and rocker arm should equal the observed lift on the flow bench needed to achieve the desired intake port flow. You don't want a doggy exhaust port, either. Depending on the engine, if the intake/exhaust-port flow ratio is 65 percent or less, the engine may not meet your power goals, although it can be crutched in some cases with a dual-pattern cam.
Stan

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  #176  
Old 02-24-2020, 12:05 PM
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ponyakr,

This thread is going nowhere and yet has been all over the place.

Stop posting all kinds of links to different engine specs and engine builds.

Pick one engine

Check what bodes it was offered in and pick one

See what SS class it will race

We now know what it has to weight and from the class index can guesstimate the HP needed to run .15 under the index.

We can now look to see what it will take to build that HP from the engine that was chosen.

Also once there is a given set of spec, maybe other will have some ideas to add.

Stan

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  #177  
Old 02-24-2020, 04:10 PM
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"...Pick one engine..."

If I pick one engine, there will be others who say, it'll be easier with some other engine. I personally think there are several engines that could possibly be built to run the index or slightly better, without gigantic mega-bucks. And I posted a list of those.

But, if you wanna focus in on just one at a time, lets 1st go with the 1977 180hp 400, with 6X heads. 285hp factor in SS. 289hp factor in GT/auto trans.

http://www.classracerinfo.com/Engine...4&MAKE=Pontiac

Not interested in the super high dollar heads & super huge roller cams & valve spring pressures needed to run really quick. Just trying to find a low buck recipe to make enuff power to run the index.

Sorry, don't know how to say it any simpler than that.

  #178  
Old 02-24-2020, 04:18 PM
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Found a link to a list of NHRA national event winners, up thru 2000. As time goes by, I'll post some of the Pontiac powered cars that got either a win or RU, both here & on the Stocker thread. Or, for those who prefer to do it yourself, here's the link.

http://www.nhra.net/50th/resultslist.html

The 1st SS win I noticed was in '75. Don't know how accurate these records are. They show that Jack Mullins won 3 events & was RU @ another. I knew about 2 of the wins, but not the other.

http://www.nhra.net/50th/results.asp?mYear=1975

The '76 list shows a win & 2 RU's for Jack.

http://www.nhra.net/50th/results.asp?mYear=1976
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Last edited by ponyakr; 02-24-2020 at 04:31 PM.
  #179  
Old 02-24-2020, 04:48 PM
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Quote:
Originally Posted by ponyakr View Post
"...Pick one engine..."

If I pick one engine, there will be others who say, it'll be easier with some other engine. I personally think there are several engines that could possibly be built to run the index or slightly better, without gigantic mega-bucks. And I posted a list of those.

But, if you wanna focus in on just one at a time, lets 1st go with the 1977 180hp 400, with 6X heads. 285hp factor in SS. 289hp factor in GT/auto trans.

http://www.classracerinfo.com/Engine...4&MAKE=Pontiac

Not interested in the super high dollar heads & super huge roller cams & valve spring pressures needed to run really quick. Just trying to find a low buck recipe to make enuff power to run the index.

Sorry, don't know how to say it any simpler than that.
Ok you need to pick a class

here are the indexes
https://www.nhra.com/stats/14-mile-i...ock-eliminator

The pdf shows the weight brakes for Super Stock and GT.

One we have a class we will know the index, be able to calculate the weight and then estimate min need HP.

Stan
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  #180  
Old 02-24-2020, 05:48 PM
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Ok you need to pick a class

here are the indexes
https://www.nhra.com/stats/14-mile-i...ock-eliminator

The pdf shows the weight brakes for Super Stock and GT.

One we have a class we will know the index, be able to calculate the weight and then estimate min need HP.

Stan
OK, I'll play along. Lets go with a regular SS class, rather than a GT, class. That will reduce the hp factor by 4hp. Every little bit helps.

OK, then in order to get by with 9" tires & Stocker type suspension, lets go with a heavier car. There are several '77 Pontiacs, with an NHRA weight of around 4000lbs. So, you could pic any of those, since they'll allow you to add & remove some weight, to better fit a class.

Let's use a 14lb/hp class. 14 x 285hp = 3990lbs. Add 170lbs for driver. Min weight is 4160lbs.

In reg SS, the 14lb/hp class is M. With an auto trans, the SS/MA index is 11.85.

http://www.classracerinfo.com/NHRA_Classes.aspx

So, the car will need to go at least 11.85. 11.75 would be safer, but not absolutely necessary.

So, there you have it. The objective is to see if this engine can be built to legal NHRA SS specs, making enuff power to run 11.85, at 4160lbs. But, the trick is to do it WITHOUT the mega buck heads & huge cam & springs that have been mentioned.

Keep in mind, the car can have a lightened, tricked out TH350, with trans brake & a 2.75 1st gear, a GOOD racing converter for the app, and whatever rear gear is needed.

If for any reason you don't wanna figure using a heavy car, then go with the lightest '77 Bird. Whatever.

The '77 Birds have an NHRA weight of around 3500lbs. So, you could run the 12lb/hp class & the wight would be 12 x 285 =3420 + 170 =3690. That's almost 500 lbs lighter. That would be SS/KA, with an 11.25 index. So, the lighter car would need to go .6 quicker, in order to be just as competitive as the heavier car. At least that's what I figured. As we've all seen, I could be wrong on any of my numbers or calculations.

http://www.classracerinfo.com/NHRA_Classes.aspx


Last edited by ponyakr; 02-24-2020 at 05:57 PM.
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