Turbo Exhaust manifold questions

[Ron240zxt]

Hello all again,

How much flow can i get out of the factory turbo exhaust manifold before it starts restricting performance by causing back pressure.

a: 300 hp

b: 400hp

c: 500hp

 

This is what it comes down to. Will i be happy with the performance of a turbo header. or should i use the factory manifold. What are the advantages/disavantages between both set ups.

 

thank you

Ron

[SleeperZ]

I don't know the upper limit, where the stock manifold makes a serious impact on performance, but I saw a L28T yesterday rip low 12's on the stock manifold. I think that is close to 400 horsies in a 240Z. Of course, he's running the stock cam as well, but a 3" exhaust.

 

If I were to try to make 500 hp, I'd go with a tubular exhaust manifold, but not for 400.

[240Z Turbo]

Ron, people are and have made 500hp with the stock exhaust manifold. However, I would do as much porting as you possible can to help flow. The inlets can be heavily ported, but the best area to hit is where cylinders 1-4 enter through 1 opening to the turbo area. If you stick your finger in there you will notice the top wall can have atleast 3/4" of material removed. Anyway, I don't think you will have a problem using it for your application. Hell, TimZ made 391hp&410ft-lbs @wheels with that manifold. However, a tubular exhaust manifold would probably net about 40hp on a big turbo application.

[randy 77zt]

i am collecting parts to build up a turbo engine with more hp.has anyone sent an exhaust manifold to extrude hone?this gets places where you cant get grinder into.

[DavyZ]

Randy, Extrude Hone is pretty cool, and if you have the bucks for their services, I'm sure they can make a good thing better! The examples of what they can do for manifolds are really stunning. I suppose if I were putting together a 500hp Turbo Z I would look them up.

 

Davy

[Guest Anonymous]

Whatever type of exhaust manifold u chose,(standard or fabricated tubular) I strongly recomend getting it ceramiced coated(HPC)inside and out,and while you're there get the exhaust housing done as well--The last turbo exhaust manifold I built using cast steel welding bends I had it HPCed along with the exh housing , man what a differance way lower under bonnet temp's, and far less lag-------GOTTA DO IT

[Evan Purple240zt]

hey turbo boy! Do you have pictures? Custom manifold is a dream, but im still curious

 

have you had any cracking, or deformity problems with it?

 

Evan

[Guest Anonymous]

Evan, the manifold was'nt for a Zed,it was for my (dont laugh) turbocharged intercooled Mini circuit car, no warpage or cracking problems at all: the key to that is keeping the primary pipes seperate all the way too the turbo flange, and making both cyl head and turbo flanges out of at least 10mm thick plate , I used 10mm for head flange and 12mm for turbo ,try and stay away from "log" type manifolds where 2 or more exhaust pulses overlap, as this is where you get differing temps along the lenght of manifold,causing cracking/warping etc, also the ceramic coating on the inside of manifold reduces the amount of heat soaking into manifold therefore reducing these problems, as well as keeping exhaust gas hotter-the hotter the gas the faster it moves= less lag

 

........hope I hav'nt bored you.