I know this has been talked about ad nauseum about for years, but I'm still curious to get an update on whether anyone on this forum has or is currently giving an effort to develop a custom TT manifold that would, say, use all of the original vaccum/pressure lines (controls).

 

As far as I know, not yet.

 

I think the housings that connect the twins are more of a bottle neck than the manifold...I could be wrong???

Would be nice to get the heat brick manifold out though.

 

There was somone on this board who claimed they were near completion on one, but that was a few months ago, and I havent seen any posts about it since. Anyways, does anyobdy have any info on the old run-of-one manifold made by HKS for twin turbos? Was that manifold to provide for a sequential operation, and what was the reason it was never put into production?

 

Buy a hunk of stainless and some dremel bits and get started!!

j/k that sounds like a lot of work/cost no matter how it's fabricated.

 

And the extreme heat of the exhaust ports also makes this a problem for fabrication.

 

Problem with the intake manifold is when you want to make power above 8000 rpm. You aren't going to do that with the twins, so what is the point of having all the vacuum line connectors?

 

Spyfish, this is in reference to an exhaust manifold that would say, use the solenoids and actuators (TC, prespool, CRV, CCV) of the stock setup (why bother reengineering that part), effectively just a manifold/twin turbo/ypipe upgrade. Heat would definitely be the biggest hurdle on something like that, ESP on the TC flapper. I was just curious about the progress people who have mentioned this before have made.

 

Ah, I hadn't really heard about that one. I think the cost of development would not be worth the end result. I also don't think that many people would sign up to buy a kit.

 

Oh everybody and their brother would sign up, it's just that when it came time to pay for it nobody would do it. Same as every other thread where somebody asks "If I make this would you buy it?"

 

R&D would be a bitch for sure..but to say its not worth it might not be a valid statement. Something like this could bascially rejuvenate the FDs status in relation to the very high HP production cars which are now coming out (say new Z06 and SRT-10, new 911 turbo etc ). It could add another another decade's worth of relevance of the car in the sports car world.

 

Before anyone says the factory control system sucks, I should also mention that the only part of it that would need to be upgraded in my opinion, would be the manner in which the secondary turbo is prespooled. That would have to be more precise than the primitive manner in which Mazda arranged that function (basically a fixed duty cycle control of the prespool door based in a binary way on RPM and throttle position). A proper system for smooth transition would involve a control law based on just one observation- how much the secondary is currently spooled, which could be determined by measuring the pressure thourgh some fixed size orifice on the secondary turbo compressor housing. Based on this observation, a duty-cycle controlled solenoid could then adjust the pressure on the precontrol actuator to allow various angles of opening of the precontrol door (between 0-100%). A simple separate ECU, boost sensor and solenoid would be all that would needed in theory to be able to dial in seemless transition.

 

Didn't RE Amemiya have one almost ready to come out? I thought I saw a stock twins manifold on here somewhere that someone posted supposedly developed by RE..

 

Would the goal be to eliminate the "log" that is thought to be the bottleneck of stock-twin based setups like the BNRs etc.?

This sure would be great, but i'm not sure whether at the point that you've payed to upgrade the two turbos to higher-flowing units AND paid for what would be an impossibly complicated and expensive fabrication job, especially to maintain a sequential operation, you wouldn't have mostly paid for a quick-spooling, ball bearing single.

 

There is no set price as of yet because of cracks. I assume stress cracks from holding the weight of the cast iron turbo manifold.

As far as the SS turbo assembly manifold, that company never got back to me.

https://www.rx7club.com/showthread.p...turbo+manifold

 

You must remember that the CRV is open and venting all that compressed air to the atmosphere. I have no problems with my boost control (spiking and dipping) with my setup. It is all in the tuning and having a free flowing exhaust.

 

True Spyfish, the CRV is venting to atmosphere during prespool BUT there is indeed also pressure at that outlet nevertheless..I have measured it before and seen anywhere from 1-4 psi depending on how much I prespool the turbo.

Peter, yes the idea would be to ditch that resrictive log. I guess the first step to this would be to get a twin turbo manifold that achieved great performance in parallel, and then modify it to allow for the sequential operation. Ultimately it would be much better than a quick spooling single. Ideally (this could be just dreaming) you would want something with the low end spool of an RX6B and the top end of a t78.

 

^ sequential would be too complicated and therefore too expensive. I don't see why a parallel setup can't be done with some SS tubes and flanges (similar to exhaust manifold).

 

A parallel manifold is really nothing hard to fabricate, and really wouldnt provide any advantage over a single.
That would be a first step (making one that performed well) though.

 

Perfomance advantage - no, price advantage - yes. Best advantage - street legal. Oh yeah, light weight compared to the cast iron setup and easy to heat coat.

 

This shouldnt be cast iron, but rather tubular (if such a setup could accomodate valves).

 

Cool, I'm glad to see that you actually took the time to measure it.

 

The stock twins exhaust manifold is so small. If your full non seq. and cut out the doors and smoothed and enlarged the stock one, theres really no need to have some custom manifold.

 

^ There is a need. It's extemely heavy and soaks in heat. A stainless steel version would be light weight and can easily be heat coated for 2k degrees.

The exhaust manifold can be replaced with stainless steel as well. RE-Amemya allready has a prototype. The problem is the cast iron turbo manifold is too damn heavy and it creates stress cracks on exhaust manifold.

 

Mazdaspeed did a set of "Bathurst turbo's" back in 95 for the series-6 (92-95) RX-7 SP. They did a run of 100 sets i heard. Only 20 came down under & the rest where sold through Mazdaspeed then Auto-Exe until they ran out.

These turbo's & manifolds all bolted straight onto the 13B as standard, with vacum pipes & working actuators etc etc

Looked identical but when you placed them alongside the normal turbo's, you could see the big differences in the manifolds & turbo sizes.

Find yourself a "super rare" set of them & your laughing