Headers too big??

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hoffman900
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Re: Headers too big??

Post by hoffman900 »

hoffman900 wrote: Fri Mar 16, 2018 5:17 pm
Casper393W wrote: Thu Mar 15, 2018 5:57 pm Hey folks,. I know we have a topic going on headers but I have a different problem... I'm building a 393w with David Vizard and I am putting it in a 71 F100. My question is...what is the most power you guys have seen 1.625 headers support? There isn't a company out there that manufacturers a 1 3/4 or 1 7/8 header for a Windsor engine in a F100... So I'm stuck with a set of Hedman street headers until I can get some custom made.

Here is a pic of the engine
Let me know what you guys think!
Here are Elston 1 5/8" tubing off the head before stepping. Of course, these aren't catalog headers.

Image
I would not be afraid at all of using 1.625 at all off an even larger port area. I do it all the time for Cobra Automotive and their nostalgia mustangs and cobras. 1.63@8-1.75@10, 2" secondary for 12-14", (not a typo) and a 2.25" choke at the final collector. 620hp no problem and all sorts of bottom end. Especially for such a small motor and road racing
It all eventually feeds into a single 3" tailpipe to exit.

In-car. The Camaro is also out of the same shop

Boss 302 Mustang: https://www.youtube.com/watch?v=t28GFX6H2tA
Z/28 Camaro: https://www.youtube.com/watch?v=HH8IPGwOLMg

It's also interesting to hear the difference between the Chevy and Ford with what is essentially the same engine specs.

The typical off the shelf catalog header will not work with those diameters.
I agree with gRobersts101 and Stats. Everything Calvin says is important (+1 to groberts), but you also can't piecewise it together. Diameters like Calvin recommends only works when you use large bend radii, seamless port transitions, and pay attention to flow in a header (+1 to Stats).
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Re: Headers too big??

Post by statsystems »

hoffman900 wrote: Fri Mar 16, 2018 5:39 pm
hoffman900 wrote: Fri Mar 16, 2018 5:17 pm
Casper393W wrote: Thu Mar 15, 2018 5:57 pm Hey folks,. I know we have a topic going on headers but I have a different problem... I'm building a 393w with David Vizard and I am putting it in a 71 F100. My question is...what is the most power you guys have seen 1.625 headers support? There isn't a company out there that manufacturers a 1 3/4 or 1 7/8 header for a Windsor engine in a F100... So I'm stuck with a set of Hedman street headers until I can get some custom made.

Here is a pic of the engine
Let me know what you guys think!
Here are Elston 1 5/8" tubing off the head before stepping. Of course, these aren't catalog headers.

Image
I would not be afraid at all of using 1.625 at all off an even larger port area. I do it all the time for Cobra Automotive and their nostalgia mustangs and cobras. 1.63@8-1.75@10, 2" secondary for 12-14", (not a typo) and a 2.25" choke at the final collector. 620hp no problem and all sorts of bottom end. Especially for such a small motor and road racing
It all eventually feeds into a single 3" tailpipe to exit.

In-car. The Camaro is also out of the same shop

Boss 302 Mustang: https://www.youtube.com/watch?v=t28GFX6H2tA
Z/28 Camaro: https://www.youtube.com/watch?v=HH8IPGwOLMg

It's also interesting to hear the difference between the Chevy and Ford with what is essentially the same engine specs.

The typical off the shelf catalog header will not work with those diameters.
I agree with gRobersts101 and Stats. Everything Calvin says is important (+1 to groberts), but you also can't piecewise it together. Diameters like Calvin recommends only works when you use large bend radii, seamless port transitions, and pay attention to flow in a header (+1 to Stats).

Ha! I should have opened this thread first!
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Re: Headers too big??

Post by BILL-C »

I have multiple sets of sb ford dyno headers that Calvin made for us. They are configured in a way that allows us to experiment with secondary pipe lengths and swap firing order easily. We have made 650+ hp with the dyno configuration of the headers in the picture posted by hoffman 900. They match or beat the lower end power of any 1.625 dia straight tube header and beat the top end power of any 1.75 header we have ever tested. They are far superior to any "catalog" header .
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Re: Headers too big??

Post by hoffman900 »

BILL-C wrote: Fri Mar 16, 2018 10:05 pm I have multiple sets of sb ford dyno headers that Calvin made for us. They are configured in a way that allows us to experiment with secondary pipe lengths and swap firing order easily. We have made 650+ hp with the dyno configuration of the headers in the picture posted by hoffman 900. They match or beat the lower end power of any 1.625 dia straight tube header and beat the top end power of any 1.75 header we have ever tested. They are far superior to any "catalog" header .
Every shop should have dyno headers of that caliber :shock:

My guess is the mainstream thinking on some engine items would change if that were the case. We never met,Bill, but we’ve been entered in a lot of the same race weekend as your customer stuff. Your engines really sing and run like a freight train. Thanks for the reply.

+1 to Calvin’s work being far superior. I let him know about this thread. Maybe he’ll chime in when he gets a chance.
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Re: Headers too big??

Post by exhausted »

The first thing I learned in early 90's doing Cup stuff only was fewer and larger diameter bends trumped equal length and the headers could be one size smaller diameter if the layout allowed better flowing tubes.
Makes it hard to advise others what size to make their headers. It has always amazed me how easily people can do things in headers flow-wise they would never do on the intake side. Flow is horsepower, but if you want a strong power curve you have to deal with pressure waves tuning. You have to keep them back somehow. Smaller tubes and chokes and AR valves in some combination.
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Re: Headers too big??

Post by exhausted »

The first thing I learned in early 90's doing Cup stuff only was fewer and larger diameter bends trumped equal length and the headers could be one size smaller diameter if the layout allowed better flowing tubes.
Makes it hard to advise others what size to make their headers. It has always amazed me how easily people can do things in headers flow-wise they would never do on the intake side. Flow is horsepower, but if you want a strong power curve you have to deal with pressure waves tuning. You have to keep them back somehow. Smaller tubes and chokes and AR valves in some combination.
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Re: Headers too big??

Post by groberts101 »

exhausted wrote: Sat Mar 17, 2018 3:47 pm The first thing I learned in early 90's doing Cup stuff only was fewer and larger diameter bends trumped equal length and the headers could be one size smaller diameter if the layout allowed better flowing tubes.
Makes it hard to advise others what size to make their headers. It has always amazed me how easily people can do things in headers flow-wise they would never do on the intake side. Flow is horsepower, but if you want a strong power curve you have to deal with pressure waves tuning. You have to keep them back somehow. Smaller tubes and chokes and AR valves in some combination.
Thanks for that Calvin. This is very logical and intuitive for those who've repeatedly built custom header back exhausts using mandrel bends. Always amazed me how a properly routed and designed 2.5" system could easily make more power over the entire curve and not give up one bit of peak power vs a crappy muffler shop compression bent 3" system tucked and twisted all to hell just to stuff a bigger tube in there. Even when using the 2.5" pipes(in/out) it also helps to find mufflers with larger 3" or better inner diameter flow tubes as well. Keep the exhaust flow moving as fast as possible and work on the biggest corks first.

Have you ever been involved or heard of anyone building a FULL AR style engine?

Meaning.. multiple A/R type devices/geometry being used from the air bells entry point all the way to the tail pipes/tips?

I am planning and designing a full A/R type engine and I still have to wonder along the way if too much of a good thing might just turn out to be a complete waste of time and resources. It is amazing how many transitional opportunities there are within the induction, cylinder head and exhaust system to implement such methodology. Just curious to what extremes you may have implemented it and/or what additional tricks you may have experienced along the way to where your current mindset is now.

Thanks,

Greg
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Re: Headers too big??

Post by exhausted »

groberts101 wrote: Sat Mar 17, 2018 4:07 pm
exhausted wrote: Sat Mar 17, 2018 3:47 pm The first thing I learned in early 90's doing Cup stuff only was fewer and larger diameter bends trumped equal length and the headers could be one size smaller diameter if the layout allowed better flowing tubes.
Makes it hard to advise others what size to make their headers. It has always amazed me how easily people can do things in headers flow-wise they would never do on the intake side. Flow is horsepower, but if you want a strong power curve you have to deal with pressure waves tuning. You have to keep them back somehow. Smaller tubes and chokes and AR valves in some combination.
Thanks for that Calvin. This is very logical and intuitive for those who've repeatedly built custom header back exhausts using mandrel bends. Always amazed me how a properly routed and designed 2.5" system could easily make more power over the entire curve and not give up one bit of peak power vs a crappy muffler shop compression bent 3" system tucked and twisted all to hell just to stuff a bigger tube in there. Even when using the 2.5" pipes(in/out) it also helps to find mufflers with larger 3" or better inner diameter flow tubes as well. Keep the exhaust flow moving as fast as possible and work on the biggest corks first.

Have you ever been involved or heard of anyone building a FULL AR style engine?

Meaning.. multiple A/R type devices/geometry being used from the air bells entry point all the way to the tail pipes/tips?

I am planning and designing a full A/R type engine and I still have to wonder along the way if too much of a good thing might just turn out to be a complete waste of time and resources. It is amazing how many transitional opportunities there are within the induction, cylinder head and exhaust system to implement such methodology. Just curious to what extremes you may have implemented it and/or what additional tricks you may have experienced along the way to where your current mindset is now.

Thanks,

Greg
Yeah, 4valve and VVT. Bunch of them out there, eh? 4 valves don't need as much cam, and you can move the cams around? That's the easiest way to deny reversion to kill your curve...
Very little being done on
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Re: Headers too big??

Post by groberts101 »

exhausted wrote: Sun Mar 18, 2018 4:08 pmYeah, 4valve and VVT. Bunch of them out there, eh? 4 valves don't need as much cam, and you can move the cams around? That's the easiest way to deny reversion to kill your curve...
Very little being done on
Lol.. sorry should have specified typical OHV pushrod 2 valvers in my question. Looks like maybe that incomplete sentence at the end of your reply would have finished off with.. very little being done with.. 2 valve pushrod motors?

Thanks for your time to reply.
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Re: Headers too big??

Post by exhausted »

Yes sorry, little reason to spend money on old technology.
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