4-2-1 turbo manifold?

[newaccorddriver]

im thinking about ditching the manifold i have now in the favor of creating something that would truly stand out in the crowd. i cant really make a 4-1 merge section on my own, so i cant really make a typical manifold. would a 4-2-1 turbo manifold be possible to make some decent power out of?

[AccordEpicenter]

you can buy prefab 4-1 collectors welded together or non welded together, i think bmc racing has some. If not, a 4-2-1 will work fine if the merges between runners are smooth

[89T]

4-2-1 manifolds are typically a longer manifold but i see no reason why you couldent do it. one thing you dont want to do is step up too big at each "y" going too large will slow the velosity of the exhaust gasses, thus the turbo will spool slower.

[newaccorddriver]

i emailed the guys at BMC, and it takes about 3 weeks to get in.

the way i see it is that the turbo will see exhaust gases from each set of cylinders that are being fired. so when one cylinder fires, gas flows through to spool the turbo while the next cylinder fires and flows through the other set of runners

[MessyHonda]

cool you got any pics of the thing? or how it will look like....how will it affect your clearance

[newaccorddriver]

cool you got any pics of the thing? or how it will look like....how will it affect your clearance

im in the thinking/designing phase right now. itll most likely be a sinktrap type manifold where those 4 runners go down and merge into 2, then the 2 runners come back up and merge into 1 for a top mount 'show quality' setup. or i can skip the top mount part and waste less material in the pursuit of savyness

[89T]

this is what i am getting at.

you want to use 1.5"(in) x 1.5" (out) for you'r first 2 "y" collectors and

1.5"(in) x 2.25" (out) for the third collector. this is the best fit for a t/3 flange.
the first 2 can be steped from 1.5"(in) to 1 5/8"(out) and the third from 1 5/8"(in) to 2.25"(out) but you will loose volosity. If you have major head work and a high reving engine this may be the way to go.

[AccordEpicenter]

ehh maybe but all the highest performance race oriented turbo manifolds ive seen have been 4-1. Either design will work just fine

[newaccorddriver]

i dont really want to wake a couple weeks for those 4-1 kits to come out, and i cant really justify paying that much for tubing with a few cuts done to them. since i cant make my own, i figured a 4-2-1 header would be a unique approach.

[newaccorddriver]

this is what i am getting at.

you want to use 1.5"(in) x 1.5" (out) for you'r first 2 "y" collectors and

1.5"(in) x 2.25" (out) for the third collector. this is the best fit for a t/3 flange.
the first 2 can be steped from 1.5"(in) to 1 5/8"(out) and the third from 1 5/8"(in) to 2.25"(out) but you will loose volosity. If you have major head work and a high reving engine this may be the way to go.

thanks for the suggestion, ill take this into consideration when i go into the building phase.

[A20A1]

Burns stainless sells some top quality merges, 4-1 or custom.... but they are pricey.

Anywho I don't really see any difference or benifit to the 4-2-1 or 4-1 on a short manifold, it wont be the same as an N/A header, that uses momentum to draw out gases since you have the turbine in the way, unless perhaps you had a long tubed manifold.


there are two pairings you can use

Sequential Pairing 180* 1 & 2 . 3 & 4
and Non-Sequential 360* 1 & 4 . 2 & 3

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[Accordtheory]

Do you know which cylinders to pair together? You want the 2-1 collector to receive alternating pulses every 180 deg..

If you really want to stand out and make more power with better spool than a 4-1 or 4-2-1 anyway, forget that last collector and get a split housing turbo.

[AccordEpicenter]

same as NA header, 1-4 and 2-3. Divided tang exhaust section turbos do work pretty good but they do tend to be on the large side, like a Holset HX35, thats a diesel truck turbo that supports over 500hp, its kinda pointless if youre only going for like 250whp lol