After a few years of struggles I'm getting around to dropping another SR into my dusty ol S13 after eating the bearings on the old one. I was running 2871r .86, HKS 264 step2 cams, 740cc blah blah... and all the normal goodies but stock manifolds. I currently have the motor out, rebuilt SR next to it, and a knock-off manifold that I never got around to installing years ago is looking more and more tempting after remembering how much crap is involed on and under the stock intake manifold.

Are the gains of this manifold worth the reported loss of bottom end? Is that an issue with larger than stock turbos or is it more limited to the stock T25? I like the idea of everything being cleaned up a little on the intake side, installing a power-adder that I already had sitting around, and easier access to the oil filter is always a plus, but at the same time I don't want to have a powerband thats only at the top. I did install an R32 rear end with the 4.36 ratio to compensate for the extra lag that the .86 added as opposed to the .64

 

If its just a knock off greddy manifold... I wouldn't. There's really no reason to. On a T2 setup, even with a 2871 you wouldn't even be close to having the need for an aftermarket manifold. Plus I've seen idle issues with those manifolds as well, and a lot of them have slag and other junk inside them.

 

I've "heard" stories about the manifolds causing engine problems but I can't recall once seeing some evidence of anything other than some leaking vacuum fittings. I think the fittings supplied with most of the knockoffs were junk and if they leak, you're certainly going to have idle issues. As for slag, this one's already been cleaned up and smoothed out so I'm not too concerned with that.

I know, a knock off is never going to be quite as good as the brand name; and ideally I would have like to have a Greddy, but I can't justify $900 for a manifold that isn't 900% better than the $100 manifolds as this point in time.

However, for the sake of moving forward, lets just call the manifold a greddy. What gains are there to be had, and what kind of downsides are to be expected. Would the gains outweigh the losses?

 

if it is in good shape, and doesn't have "weak spots" like bad welds or whatever, then swap it out.
I've not actually seen any evidence that it is going to lower your low rpm power. If anything, it is supposed to decrease spool time because it it is supposed to flow better.

personally, I would just expect the engine bay to look a little better and the engine to run the same as it always has.

 

I am with kendallh. But I do also have an sr with stock internals and no cams putting down 392whp with a stock manifold with a gt2871r .64 on 24psi. The key as Martin from R S Enthalpy is in the external waste gate that I have had him do to it. I was like you wondering if I should do an aftermarket manifold the Megan's and others that fit the t2 flange. But like some other people have said the gains aren't worth the problems. Problems being bad quality manifold that crack. But that is just my opinion.

 

Prob won't see any gains except for the fact that it will look better, but could crack later, and you will need to make a new cold pipe

 

Don't do it, unless you want to lose torque. You aren't close to maxing out the stock s13 intake manifold unless you're making 500whp. The only motor this would be worthwhile on is a low port sr.

 

1. Dont expect it to actually gain you anything.
2. Having driven T28 cars with one, I dont remember complaining.
3. Remember its knockoff junk, which has become hit and miss, some have been so bad as to leak through the porosity in the casting, others are fine, while others the threads just fall apart to the fitting holes.
4. Changing the oil filter really isnt that bad, if this is such an issue that you need to replace the intake manifold to help with it, you probably should just go buy a vehicle that offers free oil changes.