I'm going to run a Tial 38mm wastegate on a stock SR cast manifold. I already have the flange welded on. My question is, Nissan guru's can contribute, I have heard on the stock SR manifold that you need to drill a hole through the runners, because the 1st and 4th runners, don't collect into the 2nd and 3rd. I've heard that this is supposed to keep the boost from spiking among other things. Is this the correct way to run an external gate on a stock manifold. A friend of mine had one welded that was nicely done at XAT, and they drilled a small port through both pairs of runners. I'm just curious what this is supposed to do and if it effects or increases performance.

 

Drilling Ports through Runners 1 and 4 will aid in better collection and therefore the more equal relief of Boost pressure. I will tell you more is the key word in the last statement. You could drill it as much as you want and if you were to flow bench it you would not see nearly as good of results as you would on a custom manifold or a full race. I say flow bench instead of dyno because with the use of the dyno their are many variables in the equation that could effect numbers besides the changing of manifolds so this form is not as accurate as flow bench. I would recommend taking a Megan and cutting a cross section in the collector and then welding in a pipe into that collector cross section this well give you better results for more equalized boost relief. Take a look at full race's design, I am not trying to jump on their bandwagon but their product works so you can take some of their design elements and apply it to your application.

 

Yes, but Full Race starts at $1000
Cast starts at $200 with a flange added.

Once you drill your primary 38mm hole, drill at least a 25 mm hole through the wall you see dividing the manifold. No this is not flow benched or tested, but it got rid of a 3-4 psi spike I was seeing on all turbos using this kind of manifold setup.

BTW... they might not be Full-Race or PB manifolds, but if you have a budget and aren't trying to squeeze every last bit of HP out, this is a good alternative... and I have gotten 420 rwhp out of these fairly easily.


Martin
XAT RACING

 

I picked up my cast manifold for $10. So with the flange weld that's far cheaper than a $1000 Full Race manifold. This is the best alternative, in my opinion, for those of you wanting to run an external gate on a T25/T28 flange style turbo, because you don't have to worry about those thin steel manifolds cracking over time. Sure it doesn't have the best flow characteristics, but regardless it's all funneling down to a small turbo exhaust blade on a T25/T28 style turbine. I'd rather sacrifice a few ponies, and have rock solid boost, than crossing my fingers on a tubular manifold, hoping it doesn't crack.

By the way, XAT does a great job with these flanges, so if your interested in adding an external gate, running your stock manifold, give them a call. Myself and a friend are both satisfied with the quality of the welding.

Here are some pictures of mine:

 

Question. Can this same flange be welded to a tubular manifold (i.e. Megan). If so does it decrease the integrity of the manifold?

 

Yes it can, BUT due to the fact that all the Chinese tubular manifold are a little different, I would have to have the car at the shop for mock up.
Do a cast.. will not be disappointed.

Martin

 

Martin My Bad I was not saying that your product was not good or even a good solution. I should have reworded what I said and yes I believe that it god rid of a boost spike you were seeing. Not trying to be like that.

 

I was running a setup like that for about 2 years best bang for the buck. I was using it on my 2871r. to me boost was coming on alot stronger.

 

One more question. I have a pretty good carbon bit that I use to grind hard metals. Do you think it will benefit if I bore out the center divider, that separates runners 1,4 and 2,3. It's the part on the bottom of the manifold that attaches to the turbo itself. There is a small divided outlet. By looking at it, it looks like that whole divider wall can be ground down so all the runners collect together. Have you experimented with this at all, what are your thoughts on it?

 

Yes.. look at the first couple of posts in this thread. I gave a exact measurement.

Martin