Hey guys...

My 393 is going to be revamped and soon it'll start pushing 450-500 horsepower. I'm going to need some bigger headers, long tubes. I have seen a couple sets of long tubes, but they're all running about 1 1/2" primary tubes. It doesn't seem like that's going to be big enough for my motor. This thing is going to flow some serious air and I need a good exhaust system to get that air out.

I'm thinking of running 3" true duals with cats and mufflers, and want some nice long tube headers.

Do you guys know of some headers that'll work for my application?....the 95 F-150.

 

Justin, I was told from an engine builder that an 1 1/2" primary is big enough for a 393. I went though the same thing with getting my headers. For a car 1 5/8" is fine with top end. But reading your other posts about your truck It feels like I have been working on it. lol.... The research that I have done on headers to keep your tq where you want it with a truck I would stay with 1 1/2" primarys. All of this is JMHO.... Good luck.. If someone has some dyno results that would be great.

 

Well I have 1 5/8" shorties on it now...

Some guys are tellin' me 2" primaries....

 

Shorties don't have any low end to them though... My post was just what a couple local engine guys told me for a truck app. with a 393. I would like to know the correct answer also.. If there is one.

 

The shorties I have are probably intended for mild 351s...

I'll have a lot more air going through my 393 and just don't want to be undersized I guess, but I have a feeling nobody makes a serious header for our trucks that I can find.

I wish there was a way to find parts easier, it's almost like you have to hunt down the people that make them instead of the opposite.

 

Did you call someone like Hooker for your application and see what they say? I'm also trying to ask of couple more people what they have on there strokers on another site.

 

2" primaries are overkill for that setup. 1 5/8" primaries are used on 500+ hp smallblocks and will have more than enough flow potential.

I searched for about 2 hours to find a long tube set when you first posted the question. Outside of getting some custom made ($$$) I could not find anything with 1 5/8" long tubes that are designed to fit that year. The slight power difference of the shorties compared to long tubes will probaby not be noticeable with the kind of power your engine will be making. I seriously dissagree with the comment that shorties "have no torque".

What you could try, if you can weld, is to buy some flanges and build your own.

 

[QUOTE=kens64]2" primaries are overkill for that setup. 1 5/8" primaries are used on 500+ hp smallblocks and will have more than enough flow potential.

I agree....


I searched for about 2 hours to find a long tube set when you first posted the question. Outside of getting some custom made ($$$) I could not find anything with 1 5/8" long tubes that are designed to fit that year. The slight power difference of the shorties compared to long tubes will probaby not be noticeable with the kind of power your engine will be making. I seriously dissagree with the comment that shorties "have no torque".

Ok.. I should of re-read my post...What I meant was shorties have very little torque... "Compaired to a long tube header" The length of the primary creates more torque. I have had shorties on cars then went to a long tube header and wow... what a differance.. Night and Day
I still have shorties on my old 87 F-250 with a 351.. The reason for that was the fit easy.. Like I stated above it would be nice if someone had some dyno numbers on this.

 

This is a post back when I asked a question somewhere else....

I have the standard 1.5" primaries. I think 2" primaries is rediculously large. That wouldn't be good except for an all out race engine. He definately is killing his performance with that. I am using the 1.5" primaries into 2.5" exhaust to keep the low end torque up. I read an article where they test different headers on a Chevy 383. Up to about 3000 RPM the 1.5" primaries kept torque up by about 10 to 20ftlbs with 20 being around 2000RPM. IT was about the same between 3000 and 4000RPM and then then 1 5/8 primaries kept torque up about 10 to 15ftlbs after 4000 RPM.
I havent even had mine over 3700RPM yet and am mostly below 2000 so I stayed with the 1.5" to get the best performance for my usage. You need proper exhaust flow through the primaries to scavenge exhaust from the cylinder. Smaller headers work better for lower RPM's.

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'76, 5.5inch lift, 4.11's, wide ratio toploader, 35x12.50's MTR's, 408 (SCAT cast crank, 6.2 H-rods, SRP pistons, 9.6:1 compression, AFR185's, Stealth intake, Extreme Energy 218/224 cam, Pro Magnum roller rockers),
670 truck avenger carb


I hope this helps a little... Just another opinion out there. I guess it boils down to where you want your power...

 

The engine will be operating to 6000 rpm.

I think calling a few manufacturers and asking what they have to say regarding flow is a good idea. I'll let you guys know what I find out.

 

[QUOTE=MustangGT221]The engine will be operating to 6000 rpm.

Is 6k for mud bogs? Where will your main rpm range be? Will you be towing with it? Anyway, please let us know when you find something out.

 

It's an on road/off road rig...towing...hauling...you name it. It's a wide scope vehicle.

It's operating range is about 1500-6000. It's not a high winder with all it's power up top. Think of it as being in the middle of a low rpm torque monster and high rpm race motor.

 

2" really is overkill for that engine. Full out race built 460-572 cubic inch engines are using 2 to 2 1/8" primaries and they're running 6000 and higher rpm all the time. Hell, my 460 is 550 horse and I'm only running 1 7/8" primaries. If you go too large you'll kill your low end.