Loot
Member
wondering what exhaust pipe size people are running in there 318's and what I should be looking for I only have an upgraded intake currently. Was thinking of doing a 2.5 Id.
318 exhaust size
- Thread starter Loot
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2.5 works fine ..... and not just for 318's, but 340's & 360's as well.
Loot
Member
Okay perfect just needed someone with some knowledge to agree with me.
d1970
TODAY IS A GOOD DAY TO HAVE A GOOD DAY
318willrun knows his stuff. Stock 318 cars had 1 7/8 down pipe connected to 2 1/4 inch pipes, so an upgrade to 2 1/2 inch system would work great.
Loot
Member
Wow that looks nice. Is that cross pipe in the middle functional? Similar to an x pipe?
2.5" Jegs on my Duster/318
And on my 360....
And on my 360....
yes that was what was used before the X pipe!
I've run 2 1/4"...
yep, and even a good 2" dual exhaust will work fine on a mildly built small block
A dual 2 inch is closer to a factory dual exhaust. Minor gains. But they are there.
A dual 2-1/4 is fine for minor engine upgrades. The most modest cam should be employed at max.
A dual 2-1/2 should be the standard exhaust size with or without headers. It is an excellent size for power and decent sound control for street or street strip vehicles. You should be able to go very fast with a 2-1/2 exhaust.
A 3 inch exhaust should be used on a heavy hitter. N02, turbo/supercharged engines where there at least 85% track. On the street, they tend to be loud! A pain to fit vs. a 2-1/2 exhaust though a few here do run it. I just find it a hard pressed reason to use a 3 inch exhaust on something like a street strip ride where it is in the street 80% of the time.
Can you find useable power in a 3 over a 2-1/2 for street vehicles? Sure! But is it really necessary?
A dual 2-1/4 is fine for minor engine upgrades. The most modest cam should be employed at max.
A dual 2-1/2 should be the standard exhaust size with or without headers. It is an excellent size for power and decent sound control for street or street strip vehicles. You should be able to go very fast with a 2-1/2 exhaust.
A 3 inch exhaust should be used on a heavy hitter. N02, turbo/supercharged engines where there at least 85% track. On the street, they tend to be loud! A pain to fit vs. a 2-1/2 exhaust though a few here do run it. I just find it a hard pressed reason to use a 3 inch exhaust on something like a street strip ride where it is in the street 80% of the time.
Can you find useable power in a 3 over a 2-1/2 for street vehicles? Sure! But is it really necessary?
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A while back, I called flowmaster about exhaust on a Dart, and they said 2.25 exhaust (duals behind headers) would support 450 hp. Just what they said
*I Think* it was Flow master, but for sure other muffler/exhaust companies had charts that related and engine size, given performance perameters (HP) & there suggest pipe size for use with that power. I haven't seen it in quite a while.
While I would agree with that pipe size statement, I myself would go up one size. In most cases (that have crossed my path) the next size up never hurt performance. Even more so on a boarder line-ish power level when the question of what size pipe should be used. That's why I did my "Suggested pipe size list." the way I did.
(Which I know see needs a spelling edit!)
mderoy340
Well-Known Member
I run the 2.5 Summit kit on my 340, it works great for the street and is quiet. I have manual cutouts and the car runs a tenth quicker uncapped.
DartGTDan
'71 Dart GT Fan
I run factory exhaust manifolds with 2 1/4" pipes, to FlowMaster 40s on my '71 Dart GT.
BigBlockMopar
BigBlockMember
Something I knew upfront got confirmed as an eye-opening experience on the dyno tonight.
Stockish 318s with 2.5 dual exhausts leave power on the table.
It had stock castiron manifolds with dual 2-1/4" seperate exhausts into turbo muffler like mufflers and tailpipes.
Now there's a pair of full length Doug's headers, 2.5" dual exhaust, X-pipe, Borla ProXS mufflers and tailpipes. This setup makes 20 (!) ft/lbs less @ mid range and about 8hp less at WOT.
Stockish 318s with 2.5 dual exhausts leave power on the table.
It had stock castiron manifolds with dual 2-1/4" seperate exhausts into turbo muffler like mufflers and tailpipes.
Now there's a pair of full length Doug's headers, 2.5" dual exhaust, X-pipe, Borla ProXS mufflers and tailpipes. This setup makes 20 (!) ft/lbs less @ mid range and about 8hp less at WOT.
What cam in the teen? sounds good.
Please explain.
Manifold vs header comparison. Moparts on the Web - Main Index
Simply put, just to much of a good thing isn't a good thing.
With the headers into the exhaust pipe into the muffler, the collector becomes to long and it lost the pressure wave tuning. The muffler used is just like extending the exhaust pipe.
A stock/near stock 318 is often best with a 2-1/4 exhaust pipe w/a H or X into a turbo muffler. If you could put the muffler closer to the header that would be preferred since the power level is low with small cam size.
This is what I have personally found.
If you can make it sing better with a 2-1/2, go for it and share!
BigBlockMopar
BigBlockMember
Meaning a too large exhaust can/could cost more in power than headers or a digitally tuned ignition curve could make up.
Thanks guys. I thought that's what you meant. More is not always better! I think the HP single exhaust on the early A's was the same. It worked better than a dual system on a stock engine. I'm from Iowa, I was corn-fused!
The summit cam kit 109.99 to yer door... LOL. Not the 6900/6901, the other cheapy. I think its the old crane fireball????. .454 lift/272 adv. dur.
It was part of the low dollar 318 build.....
Thanks. I wonder if the Summit cams are ground by Crane?
I believe so..... or used to be. However, the lifter boxes said Elgin. I cannot complain at all, cam and lifters for 109.99. When I did that project, I had to keep it under 500 bucks, so that's why I picked that cam. That being said, I'm happy with it, especially for the price.
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