400 Exhaust Pipe Diameter
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400 Exhaust Pipe Diameter
I am finishing a mild 400 buildup that I started over 10 years ago. The truck is a 1978 F150 2WD longbed.
I finished the engine over 10 years ago and never put it back in the truck. I am tearing it down cleaning it and putting it back together.
These are the parts I purchased new 10 or so years ago: Performer intake (EGR) and matching cam. Roller timing chain and stock compression pistons. I have a set of headers but can not recall the brand. I asked Edelbrock what headers to get, either they told me what model or what size runners to get etc.
I need to put an exhaust system on the truck. An exhaust shop is not a great option in that I live in the middle of nowhere. I found these pipes from hooker, they are sold without mufflers. The truck has a 2nd gas tank between the drive shaft and the frame so both pipes need to run down the right side of the truck.
http://www.jegs.com/i/Hooker/520/16561/10002/-1
That should work with a bit of modification but it is only 2 1/4 OD pipe. It sounds a bit small. Suggestions?
LMC truck used to carry a set of pipes for this setup but I did not see it when I check online.
I finished the engine over 10 years ago and never put it back in the truck. I am tearing it down cleaning it and putting it back together.
These are the parts I purchased new 10 or so years ago: Performer intake (EGR) and matching cam. Roller timing chain and stock compression pistons. I have a set of headers but can not recall the brand. I asked Edelbrock what headers to get, either they told me what model or what size runners to get etc.
I need to put an exhaust system on the truck. An exhaust shop is not a great option in that I live in the middle of nowhere. I found these pipes from hooker, they are sold without mufflers. The truck has a 2nd gas tank between the drive shaft and the frame so both pipes need to run down the right side of the truck.
http://www.jegs.com/i/Hooker/520/16561/10002/-1
Competition Exhaust System
Header Back
1978-78 Bronco 4WD; 1977-79 F-150 4WD; 1977-1/2-79 F250 Low Profile, F350 4WD w/ 351-400M
Part Number # 520-1656
Header Back
1978-78 Bronco 4WD; 1977-79 F-150 4WD; 1977-1/2-79 F250 Low Profile, F350 4WD w/ 351-400M
Part Number # 520-1656
LMC truck used to carry a set of pipes for this setup but I did not see it when I check online.
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Originally Posted by 79f100six
I have a 78 motor that is stock except for intake and 600 cfm carb and i ran 2 1/4 and my truck runs good and sounds even better. But i have straight pipes though.
Straight pipes are not an option. I like the sound of magnaflow mufflers. The plan is to run the pipes all the way out the back to keep the cab quiet on longer trips.
Since I am using an aftermarket intake and exhaust do you think 3 inch pipes would be a better choice ?
Plans are to add either a gearvendor OD or an aftermarket overdrive replacement for the C6 next summer.
You have quite a collections of 78's.
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From: Calgary Canada
I don't think you need much larger than 2 1/4" for a daily driver application. At lower RPM's they will flow plenty.
Of course this is just a wild-assed guess. Others may think differently.
Of course this is just a wild-assed guess. Others may think differently.
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Originally Posted by seventyseven250
I don't think you need much larger than 2 1/4" for a daily driver application. At lower RPM's they will flow plenty.
Of course this is just a wild-assed guess. Others may think differently.
Of course this is just a wild-assed guess. Others may think differently.
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I have been doing some more reading and found an aricle on header design that convinced the that the 2 1/4 pipes will be fine.
http://crankshaftcoalition.com/wiki/Header_design
http://crankshaftcoalition.com/wiki/Header_design
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Im not totally convinced by the article, I went from running a mild low sc (8.7) 351m with a big cam (282int-290ext) with stock mainfolds and dual exhausts to special 4 miniheaders. These 4 miniheaders collected with 2" pipes 2 cylinder per tube into 2 1/2" collectors each pair giving me 4 exhaust pipes exiting behind the front door of my car. That would seem extremist for a miled low cr 351m but it wasnt at all, my car went from revving 5k to 6k making more power. It lost some low end but not as loosing the whole thing! I still rejetted my carb. Im turning it right now into a ful 400 and checking the effect of these miniheaders on it....
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The 400 in my Crew Cab has been worked some, and is running headers as well, into 21/2" pipes, to Cherry Bombs and into 3" pipes out the side like the Lightning. Sounds and works well. I had the shop run the pipes down the right side as well, since I also have the middle tank, they had to do some real funky bends to the left pipe to get it across. Going to fix that soon. I think in your case 21/2" pipes would probably be the better choice, 3" would be too large, and I think 21/4" is a little on the small size.
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Originally Posted by Bouts21
The 400 in my Crew Cab has been worked some, and is running headers as well, into 21/2" pipes, to Cherry Bombs and into 3" pipes out the side like the Lightning. Sounds and works well. I had the shop run the pipes down the right side as well, since I also have the middle tank, they had to do some real funky bends to the left pipe to get it across. Going to fix that soon. I think in your case 21/2" pipes would probably be the better choice, 3" would be too large, and I think 21/4" is a little on the small size.
Do you have a crossover on that exhaust setup? I am thinking it would be difficult to impossible without removing the middle tank.
Also the gear vendor website talks about a right angle drive for trucks with the middle tank. That sounds bad too.
I once had a 77 F150 with tanks between the bed wall and the frame. Fillers were in flaps in the front of the rear fender wells. The tanks were much thicker /heavier then a normal tank to standup to an impact.
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No crossover, the new system will have a X pipe in there. I remember seeing a system available, I think from LMC Truck, I don't know if they are supporters of this site or not, but their catalogue does show a dual setup for the trucks that takes into account the middle tank. I'm toying with the idea of removing the middle tank and running an oversize rear tank. That would make things easier.
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Originally Posted by Bouts21
No crossover, the new system will have a X pipe in there. I remember seeing a system available, I think from LMC Truck, I don't know if they are supporters of this site or not, but their catalogue does show a dual setup for the trucks that takes into account the middle tank. I'm toying with the idea of removing the middle tank and running an oversize rear tank. That would make things easier.
I found the LMC exhausts here (site was down). Top set is for use without a center tank and applications as 73-76. The bottom set if for use with the center tank and shows applications as 77-79. No X pipe or crossover on either. I am thinking the top set should work on 77-79 too.
What I do not like about the set (bottom) for use with the center tank is that the drivers side pipe must be 2 or 3 feet longer. Not sure how much that matters. Do not see a good way to put a crossover or X pipe on it.
I found a nice system from a company called pypes that has an x pipe. Includes mufflers and hangers. It is a $438.
.
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When I had mine done the crossmember right after the header collector was completely in the way, hence some funky 90 degree bends over to the right side then down the right. I'm still not decided if I want to go the flatbed or rebuild the shortbox, that may determine if I go with a complete system under the truck or run stacks. Time will tell, and $$
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Are you talking about the crossmember that supports the AT. I image one could make a custom job with clearance or holes for the pipes to pass through.
I found 14 gauge mandrel bent pipes on Ebay. If the kids at school can do a decent job of welding them together that would be a way to go. It would be a bit less then the pypes setup and more durable.
The headers are hooker competition headers. Not exactly equal length tubes but they will have to do.
The exhaust is still about a month away. Just finished putting the pistons in. If I got the time I will port match the heads to the gasket/manifold. I want this thing to breath easy for MPG and some power.
I found 14 gauge mandrel bent pipes on Ebay. If the kids at school can do a decent job of welding them together that would be a way to go. It would be a bit less then the pypes setup and more durable.
The headers are hooker competition headers. Not exactly equal length tubes but they will have to do.
The exhaust is still about a month away. Just finished putting the pistons in. If I got the time I will port match the heads to the gasket/manifold. I want this thing to breath easy for MPG and some power.
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From: Colorado
I run 2.25" dual exhaust on my 79 f-250 4x4 with a 400. I tried bigger exhaust, it slowed it down, tried open exhaust, it slowed it down, went back to my ugly 2.25" setup and runs like im used to. Im planning on some time over the summer putting factory manifolds back on it (ran better with manifolds than headers) and then doing 2.25" down pipes off the manifolds into a single 3" exhaust. The truck is the one in the link in my signature.