Is 3" exhaust to much for a 318??

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Firemybird

Firemybird

Firemybird
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Riverside, CA!!!!
I have headman headers with a 3" collector, 3" "H" piping into 3" flowies dumped right before the diff...

I bought the car this way, it sounds fine at a higher RPM or right when i come off from idle (nice, strong and pronounced), but inbetween the two it's kinda choppy and loses almost all it's tone......

I was wondering if maybe my exhaust is to big for my motor (318LA). The only mod i have besides the exhaust is a mild cam.....

Thanks!
 
if its stock yes, thats what i have. There is no low end torque. I went to this because im building a 360 and is the only reason why i went to 3
 
So do you think i should go down to the muffler shop and have them replace the 3" with a 2 1/2"??

the only mod's i'm gonna do in the near future is a aluminum intake manifold and a 600cfm carb.....
 
Get some tailpipes on it,go down to 2 1/2 or 2 1/4 and tell the muffler guy not to weld it together that you might want to change it later,that's all just sh oot for the (I can change it later if I dont like it) the tailpipes will wake it up.you should go for the 2 1/4 pipe with what you have or smaller just save the big stuff for just in case
 
3" would be good for a Forced Induction 318-416, but for a NA 318...2.5" is probably overkill.

Nice Color.
 
Prine said:
3" would be good for a Forced Induction 318-416, but for a NA 318...2.5" is probably overkill.

Nice Color.
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Thanks, it's still got the factory paint job on her... She sure wasn't that shiney when i got her 8).......

Also, your saying that even the 2 1/2" would be a little too much??
Could i still use my mufflers??
 
Longgone said:
Or you could build a 500 hp + engine? :toothy10:
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That's true. From my reading of much exhaust tech articles and such the 3" will hurt any motor unless you are over 500 hp. You would be better off with a 2 1/4 pipe, but no larger than 2 1/2.
 
While I agree that motor would be fine with 2.25 from my experience I have never noticed a loss of torque from running 3" pipes on a mild small block.

I went from 2.5" to 3" on a mild 340, low compression, headers and intake and carb. I didnt notice a loss of torque. I ran 2.5" on a 318 B body. Motor was stock except for the electronic ignition. stock 904 and converter, 276 gears. It had no problem spinning the tires.

I would keep what you have and maybe add a set of 2.5" tail pipes.
 
well you said mild and his is basicly stock, you ran yours on a 340, thats already more HP than a stock 318. I know i have a 318 with a intake, carb, headers and a carb spacer.
 
I think people are quick to spend others money, If the exhaust is in good shape I see no reason to replace it. Theres really no difference in a pair of 2.25" flowmaster or a pair of 3" flowmasters other then the size of the pipe going in it.

They are chambered mufflers and the chambers dont change with inlet size so to replace the mufflers with another pair of Flows is a waste of money to me. He would be slowing down the exhaust gasses with smaller pipe but pretty much be feeding them in to the same muffler. It may bring torque up a bit but not enough to be worth the investment unless he find a shop willing to do it real cheap and can sell the old system to offset the cost.

I bet a bit of time spent on ignition and carb tuning would bring his toque to were it should be.
 
ya do the 2 1/4 piping from the mufflers to the back and that should help a bit
 
AdamR said:
I think people are quick to spend others money, If the exhaust is in good shape I see no reason to replace it. Theres really no difference in a pair of 2.25" flowmaster or a pair of 3" flowmasters other then the size of the pipe going in it.

They are chambered mufflers and the chambers dont change with inlet size so to replace the mufflers with another pair of Flows is a waste of money to me. He would be slowing down the exhaust gasses with smaller pipe but pretty much be feeding them in to the same muffler. It may bring torque up a bit but not enough to be worth the investment unless he find a shop willing to do it real cheap and can sell the old system to offset the cost.

I bet a bit of time spent on ignition and carb tuning would bring his toque to were it should be.
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If it was mine and I wanted to go down in the exhaust size from 3" before the mufflers or after I would use the same mufflers. A good exhaust shop can cut and down size the outlets of the mufflers to accept 2 1/2 or 2 1/4. They did it on mine so I didn't have buy new mufflers because the mufflers was just about new.
 
So.... With a mild cam, aluminum intake manifold, 600cfm carb, and all the right little stuff.....

Will i be puting out enough HP or exhaust flow to fill my 3" exhaust??
Also, would you highly recommed the tail pipes because i kinda dont like the look of them?.?.?.
 
I recommend tail pipes to keep the exhaust out of the car. Much healthier, LOL

But Its been a long time since I have had a car with tail pipes on it. Mostly because I'm cheap.
 
AdamR said:
I recommend tail pipes to keep the exhaust out of the car. Much healthier, LOL

But Its been a long time since I have had a car with tail pipes on it. Mostly because I'm cheap.
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LOL, that is true... I get more than my fair share of beautiful high quality southern california air with out the help of the ol' swinger, i'm sure the exhaust gas's creeping up into my cab only make it worse!!

BUT, you can't beat the smell of unburnt gas in the morning :love7:!!!
That and wakeing all my neighbors up is a plus too :-D!!!
 
Also, would you highly recommed the tail pipes because i kinda dont like the look of them?.?.?.[/quote]


Just have the shop put turn downs on the pipes befor the bumper. That will make them harder to see.

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Firemybird said:
I have headman headers with a 3" collector, 3" "H" piping into 3" flowies dumped right before the diff...

I bought the car this way, it sounds fine at a higher RPM or right when i come off from idle (nice, strong and pronounced), but inbetween the two it's kinda choppy and loses almost all it's tone......

I was wondering if maybe my exhaust is to big for my motor (318LA). The only mod i have besides the exhaust is a mild cam.....

Thanks!
Click to expand...

The previous owner must have had big plans for your car to put such a large diameter exhaust system on it. Stock 318`s probably have a 1 and 7/8" tubing ( no larger than 2" ) and many reduce the size after the muffler in order to keep temperatures high and exhaust gases moving. Like most everybody has said here ,tailpipes a size or two smaller may help some but probably will be of little consequence.
 
Well i got a little problem.... My dart has the (im assuming factory) towing package on it that i would have to remove before i have tail pipes installed...

Heres my problem, should i ditch the hitch or keep it?!?!
I'll never use it, EVER!!!! Is it a rare option?
 
Firemybird said:
Well i got a little problem.... My dart has the (im assuming factory) towing package on it that i would have to remove before i have tail pipes installed...

Heres my problem, should i ditch the hitch or keep it?!?!
I'll never use it, EVER!!!! Is it a rare option?
Click to expand...

I believe you have answered your own question. :-D
 
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