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2.5? N/A exhaust downpipe

B

bkaushansky

Member
Joined
Jun 13, 2021
I know this shouldn’t be so hard… can someone point me toward a 2.5” N/A exhaust down pipe for ‘88 240. Stainless and USA preferred. Planning to build the remainder of the system from scratch but didn’t want to reinvent the down pipe.

OR

A good quality 4-2-1 header that won’t disintegrate in a year. 2.5” (63.5mm) termination.


Thanks much.
B.
 
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Budget: yes! Not looking for custom header
Mods: cam, will be free flow exhaust, and working on MS just because I can. Ultimately will go +T for low 200?s range.

I can weld but don?t want to build header from pieces. Will gladly modify though.

Thx.
B.


Bready said:
Budget? Current/future modifications?
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the kl one barely fits and will disintegrate in a year, ask me how I know.

Right now I am running a stock cast manifold and a cleaned up ipd stainless header pipe and feels the exact same butt dyno wise as the kl header. Sorry I couldn't help more. It terminates in 2.25
 
Of the stuff you can do to wake up a non turbo 240 economically, opening up the exhaust would not be on my list. Stock manifold+downpipe is pretty good. Stick to cam+compression, or just a cam.
 
redblockpowered said:
Of the stuff you can do to wake up a non turbo 240 economically, opening up the exhaust would not be on my list. Stock manifold+downpipe is pretty good. Stick to cam+compression, or just a cam.
Click to expand...

Came here to say this.
The stock cast manifold is good for substantially more HP than most will ever make NA.
The best thing you can do is upsize and shorten the secondaries in the down-pipe, and move to a 2.5" system after that.
 
Yeah man. Just build a simple 2-1 downpipe and leave the header alone. Then 2.5" all the way to the rear. It's what I'm going to do with mine.
 
Just as a point of reference, a 2.25" 16ga pipe will support just south of 180hp, and by that I mean it's absolutely not a restriction to that point. 2.50" will do about 200.
 
I can't find the pic at the moment, but it is recommended to enlarge/rework the transition at the end of the n/a downpipe to 2.5" and use 2.5" from there back.
 
HiSPL said:
Yeah man. Just build a simple 2-1 downpipe and leave the header alone. Then 2.5" all the way to the rear. It's what I'm going to do with mine.
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I just cut off the cat flange and put the 2.5 pipe onto the end of the oem pipe (my guy welded it but I'd recommend using a clamp instead).

No disagreement on the 2.5 vs 2.25 - I had bigger plans for the car so opted for the larger and really the cost is pretty negligible :e-shrug:
 
Can anyone recommend a quality downpipe. Tons on ebay, IPD sells one, but without seeing it in person its hard to tell whats good.

Taking recommendations above, I'm going to widen the end to accept 2.5" and go 2.5" back. I can weld basic pipe, so that's not an issue.
Thanks.
B.
 
bkaushansky said:
Can anyone recommend a quality downpipe. Tons on ebay, IPD sells one, but without seeing it in person its hard to tell whats good.

Taking recommendations above, I'm going to widen the end to accept 2.5" and go 2.5" back. I can weld basic pipe, so that's not an issue.
Thanks.
B.
Click to expand...

I'd suggest just using the OEM pipe, cut off the flange, put the new pipe over that. Getting rid of the stock cat, and the two mufflers are what are going to give you the bang for the buck - I don't think you'll get much in terms of a return on your investment in some aftermarket down-pipe with your performance goals. Just my thoughts.
 
rearwheelpeel said:
Can anyone tell me what it is about the kl header that makes it barely fit? I?ve got a kg trimming header im about to attempt to install on my 76 B21.
Click to expand...

The two main fitment issues were it was ~10mm too close to the control arm mount rear bracket and the exit should have been about 30mm lower as it was intersecting with my m46 crossmember. I had an exhaust shop cut it and remove some material to tweak where it was pointing. Both tighter to the engine and aimed lower down. Cut right where the 2 parallel pipe 90 degree bend was. It would have been fixable at home with a welder or even maybe an apparatus to bend pipe.

Another thing I forgot to mention is it makes oil filter changes suck. Very little clearance but it's doable. I like to do my oil changes hot too so I have a couple burn scars now :lol:
 
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