Downpipe ideas for my turbos
Downpipe ideas for my turbos I have huge restriction issues with my 76/82 borgs. I'm currently only running dual 3 inch downpipes down to the driveshaft loop then into a single 4. My plan is to make dual 4 inch ones that will dump a few feet away with boost activated cutouts at 2 psi. My issue is I only have 8.5 inches between the turbos so I'm going to have to do some pie cutting and merge the 2 4 inch pipes together into 1 for a foot or so. Will this be sufficient exhaust for these things?
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From: Norn Iron
Your intake plumbing does restrict options there.
Ages ago, Hugh Maccines turbo booked mentioned using a top hat type discharge for the turbine housing where space was very limited to turn.
The hat section gives room for the gases to exit and expand, with the pipe discharge just a vent really. So whilst it appears it doesnt flow smoothly, it can still do the job well.
Or if you could angle your turbos a little, you could crossover the discharge to opposite sides, rather than trying to do a U turn back to the same side ?
Fabrication donuts also allow smooth tight turns.
Or whilst a different application, you could turn and merge immediately ? The larger you make the merge, gives both turbos plenty of volume to expand into, which is largely what you want, then after a large expansion chamber route the exhaust how you want
ie
Ages ago, Hugh Maccines turbo booked mentioned using a top hat type discharge for the turbine housing where space was very limited to turn.
The hat section gives room for the gases to exit and expand, with the pipe discharge just a vent really. So whilst it appears it doesnt flow smoothly, it can still do the job well.
Or if you could angle your turbos a little, you could crossover the discharge to opposite sides, rather than trying to do a U turn back to the same side ?
Fabrication donuts also allow smooth tight turns.
Or whilst a different application, you could turn and merge immediately ? The larger you make the merge, gives both turbos plenty of volume to expand into, which is largely what you want, then after a large expansion chamber route the exhaust how you want
ie
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From: Norn Iron
How flow vs CSA goes...I'm not sure, but a single 4" pipe has only a little smaller CSA than a pair of 3" pipes. And depending how far back the merge was, it may not really be the problem.
Either way, bigger is better, and a said 4" downpipes are maybe out of the question, but 3.5" would be a huge step up vs a 3", some 35% or so larger CSA.
And even if it meant merging 2 pipes like the Mambo setup...again it's merging into a larger volume which can be a good thing, after all, there's only ever 1 cylinder firing at a time, and discharging at a time ( although there might be some overlap )
Either way, bigger is better, and a said 4" downpipes are maybe out of the question, but 3.5" would be a huge step up vs a 3", some 35% or so larger CSA.
And even if it meant merging 2 pipes like the Mambo setup...again it's merging into a larger volume which can be a good thing, after all, there's only ever 1 cylinder firing at a time, and discharging at a time ( although there might be some overlap )