For all of you that have seen my custom turbo manifold thread, I have received a lot of inquiries about building them as a production item. I'm thinking very seriously about doing just that, but I wanna know what the majority of you would like to see in a manifold design.

I'm looking to compile a lot of information about what all you turbo guys would like to see in a manifold.

Questions?
1. How long of runners would you think are the best length for a race type manifold?
2. T3 or T4 style?
3. One wastegate or two?
4. Fully divided or undivided?
5. Why type of wastegates?
6. Turbo placement?
7. Fitment on different cars?

Other comments...
Any of your ideas, comments or generation differences will be much appreciated. I am modeling this manifold off of my S4 Turbo2. If anybody's close to my area and is willing to bring thier 3rd Gen. here to help design a manifold for FD's that would be really cool!! Feel free to go crazy with your posts. You're only limited by your imagination. Thanks in advance!

 

You could make both T3 and T4 style flanges, and then just weld on whichever one the customer needs, it shouldn't be that hard to offer both.

I think most people would preper a single wastegate. That's all 99% of the people on here really need anyway. Keeps manifold construction simpler and cheaper.

Does it matter if the manifold is fully divided and it is being used on a regular single entry turbocharger? If not, then might as well make them all divided.

 

For sales number I would suggest you try to build a mani that would duplicate the popular HKS/XS/SR cast manifold turbo and wastegate(single) locations with a fully divided T4 style turbo flange (fits the SR KKK, T78, and T4 style turbonetics, garret, and innovative turbos not to mention other T4's) and HKS style 4-bolt wastegate flange. Not knowledgable enough to talk runner length but with skills shown on your mani I'm sure you could find a way to get near optimum runner length in there. This would let any of those owners easily upgrade from a cast manifold, should sell in huge numbers, I would buy one today.

 

This is really good feedback....Thanks guy's

Does any one have a cast mani I can borrow?

 

Fully divided would be good. But I Speculate that
to keep the benifits of the divided turbo the wastegate
plumbing must keep the runners divided upstream (not short them together). That is one of the reasons I used two 35s on my manifold. With a single gate keeping them seperate becomes a bit more work. The other benifit of two 35s is 70mm of flow for < $500. But a
disadvantage of two 35s is plumbing the dump tube
into the exhaust becomes more difficult.
Which leads me to another thought. How about a
manifold for a t4 with a matching down pipe that
bolts on to the factory exhaust (at least the same location) and piping for the wastegate to the down
pipe?
The hidden bitch with a custom manifold is the fabrication of the exhaust downpipe, o2 bung,
v-band.
If something like that could be had for a reasonable
price I would get one.
jp

 

actually a pair of 35 is closer in flow to a 50 or something like that, 2 35's have the same open area as a 50

 

first off... what is the projected price? i mean if they are good bargin then i would definitly buy one... if they are super dupa expensive like chrisspeed's manifold art work then i would have to pass...

what i would think is thebest is somehting that is exact like the HKS cast manifold for FC, but fully divided.

with single wastegate either TIAL or HKS wastegate.

 

Well it seems like alot of you are looking for cheap manifolds. This is not what I had in mind, but it is not out of the question. For those of you that have not seen my other post here is a link.

https://www.rx7club.com/forum/showth...hreadid=152645

What would you think about a mild steel manifold that's been coated? I'm asking this because after doing some math I found that most of my costs are due to the flanges, the material is very expensive. Just a thought.

Can anyone post a link to crispeed's mani info?

 

I stand corrected about the gate flow
the area of 2 - 35 is about = to 1 - 50.
Thanks for the correction.

But I think cheap and durable are most important
to me. Coated steel would be fine. Stainless looks
cool but most of us are looking for functionality rather
than looks.

jp

 

to plumb a single wg to a fully divided mani, you just need a wg runner from ea. side of the divide and "y" them together into a single wg. this'll make it cheaper than having 2 wg's and simpler to plumb the wg into the dp. as for the length, you should contact someone w/ experience in pressure wave tuning on rotaries. i'd assume that it would be different than w/ piston engines, cause the exhaust port is closed for a shorter period of time on a rotary, thus changing the dynamics of the pressure waves. rotaries do offer some overlap, especially ported ones, so a mani. tuned to take advantage of that should make good power and low end torque.

 

if your make a manifold off the hks/xs cast design, I think you would be better off looking at the hks stainless manifold. the cast ones sit down to low and turbo selection is limited. with the stainless you car run a bigger turbo and not hit the frame rail. I have some pics comparing the cast and stainless if you want to look at them from a design point of view.

honestly I don't think it would even be worth your time to do this. you do some awesome work, but for the effort and money you spend making these no one is going to want to pay what they are worth. most people I see don't even want to spend $150 for a good manifold. I would be suprised if you can make yours for less than 500-600

with the influx of all the obx manifolds the market for manifolds has gone downhill even if the product quality is not on par.

James

 

The HKS tubular is like $850!!! What is your custom manifold gonna cost?