Exhaust manifolds for Turbo.

[240sxin]

So i have been searching both here and on Goolge for aftermarket exhaust. I just recently bought an 87 300zx Turbo and both the manifolds are leaking. I know I could just replace the studs and be done with it, but I figure if I'm going to go through all that trouble I might as well upgrade a little. Was also wondering if the factory could be modified to be better flowing (ported/polished?). Any info would be great, and I honestly did try to search before i came here. Can see my Z here my-new-old-z-87-300zx-turbo-t524713.html

Thanks.

[Perrenial Badass]

They can be polished up and port-matched. I have also seen people modify the transition into the crossover pipe to smooth out the flow, but that only really helps the PS bank. The stock Z31 manifolds, port-matched and polished, are not supposed to be a bottleneck until somewhere in the range of 600+hp. Can't hurt to smooth those suckers out.

[evildky]

the cost of having the stockers ported is likely more than buying the satan tubular manifolds, alsthough unless your running a fatty turbo injectors intercooler and rolulator the manifold mods would be a waste

[240sxin]

Thanks for the reply. Everything I'm finding says the same thing. Good to know that they are good for what I'm doing.

[evildky]

te z31 really is an under appreciated chassis/engine, you can spend a fraction fo the money and embarrass some z32's with just an intercooler and some tuning you'll have a great gain for minimal money

[240sxin]

So i have an exhaust leak on both manifolds from broken studs. I really want to replace all my studs with arp or something equal. What i was wondering is how hard is it to get the broken studs out. The car is my daily driver and i have accesses to a shop with everything I'll need. How hard is it to do the studs while the motor is in? If i had to pull the engine what kind of down time am i looking at? I only ask this here cause I'm having a hard time finding write ups that leave the engine in the car. Was wondering if anyone here had experience dong the studs with the engine still in. I was planning on doing my fly wheel/clutch at the same time so the transmission wouldn't be in the way. Any info would be great, thanks guys.

[evildky]

it all depends, sometimes a broken stud can be turned out ith a wrench, scredrivers removal tool etc, sometimes it simply has to be drilled and retapped or helicoiled, if thts the case then the engine or at lease the heads ill need to come out, not a lot of fun but sometimes it's the only solution no moatter ho unpleasant

[240sxin]

So if i bought all the gaskets needed, got all the parts i needed, and replaced stuff as i went. About how much down time am i looking at to pull heads/reinstall them? This is my daily driver and i have no other car so need a round about time frame if anyone knew.

[evildky]

Depends on your skills and tools, for a stock car and you've never done this, I say planfor a couple of days, keep in mind if they go to the machineshop you'll be subject to their timeframe

[RustspecS13]

You should find some one with a welder, and use that to remove the broken exhaust studs. All you have to do is weld a new bolt to the broken one. The heat from the weld breaks the stud loose, and expands the aluminum. Half the time you can use your hand and turn it out, when its cooled off of course.

I REALLY need to make a writeup on how to do it. It'll save soo many people so much time.

~Alex

[240sxin]

I'm guessing I'll still have to pull the heads tho? Is it pretty much impossible to get the manifolds off with out dropping or removing parts of the engine? I work at a shop so i have all the tools needed to do what ever, this car is my daily driver tho, so down time needs to be minimal.

[AZ-ZBum]

You don't have to pull the heads, but it does make it easier. Or... Lift the engine enough to get to them.