I purchased my Rx7 a few years ago with the stock twin setup. Knowing that I am always wanting to go faster, and the twin turbo system is a problem waiting to happen, I started planning for a single turbo build.

20 years ago, I ran a T78 setup and didn’t really put much thought into flow, heat or data. For this build, I am trying to research as much as possible to make the best decision regarding parts to achieve a ~650rwp build.

One of the many important parts being the Turbo Manifold.

I remember Howard Coleman had an interesting manifold design that looked compact, equal length runner and single wastegate for less hardware and plumbing. For the past few years, I have been speaking to Howard (read bugging him) about producing a V2 of his manifold.




I won the battle and wanted to share the progress made.

For over two years Howard worked with Carter at High Pressure Performance(hppfab.com) to optimize the manifold. The objective was to take it from a welded state to an investment cast form. Thank you Solidworks, 3D Printing, Investment Casting and Carter.

I wanted to share a little bit of the journey and the result. The challenge was to create a fully divided short manifold with the least amount of bends for the best response and low backpressure.

Here’s a bit of the prototype process and the end product:










Being 3D printed of Stainless Steel, the manifold can maintain great flow characteristics, without welds.

I was able to get the first 3D Printed prototype from Howard. I know that he has plans and is looking into having more of these manifolds produced. With the great data and results of his V1 manifold, I am looking forward to running this improved version. I will keep everyone updated as my build progresses in a build thread.

Please reach out to Howard and bug him to make more of these manifolds.

I would also highly recommend Carter if anyone is looking for custom Rx7 work. Below is a photo of my S366 turbo with a 3.5” downpipe. I would also like to highlight Carter’s ability to work on our cars. I asked that he build my 3.5” Downpipe with recirculated WG and resonated Mid-pipe. Fab work looks excellent, and I am excited to get my build started.

Should you be interested in the thinking behind the design I suggest you visit the “System Design Section of Howard’s site:
CPR LOW DRAG TURBO MANIFOLD

Enjoy the eye candy below. This is my S366 and Carters custom 3.5" exhaust. I will likely make a new Build thread to consolidate and document my progress for the full build.

Eric

 

Very cool! I thought I had seen a cast (or printed) version of this pop up recently, somewhere!

I'm a fan of the singular large wastegate assuming there are no disadvantages. Was personally considering a Turblown V2 shorty and a turbine housing mounted gate but this looking promising. We need the man himself to jump in here with pricing and availability!

 

i am indebted to iceman for his persistent (many years) nudging me along re the manifold. in addition, he hooked me up w Carter Thompson. Carter is both a metal wizard and an actual engineer. he also is fluent in SolidWorks. maybe quantum computing in his spare time. thank you Eric and Carter.

i won't bore you w the "WHY" of the manifold as it is all on my site. i suggest anyone interested please read my "System Design Section" first, then visit the new section specifically on the manifold.

SYSTEM DESIGN

CPR LOW DRAG TURBO MANIFOLD

i am now, again, an RX7club vendor. my vendor membership is Howard Coleman CPR

while at this time i can't give you pricing i can tell you that we are not far from taking orders. the manifold will come with a well engineered-executed downpipe, and Tial 60 mm V60 wastegate. the system can be bought with or without a turbo. i sell Garrett and Borg Warner. pretty much anyone can sell you a turbo. deal w me on turbos and i hope you will find some helpful advice. there might be a new paradigm around your corner. competitive pricing of course.

 

I haven't really seen any disadvantage in my research. Conversely, one less wastegate, plumbing and line to run. All of the data I have seen from Howards original manifold look ideal for our platform. This new manifold has better transitions and is not welded, so I assume it will perform the same or better than his original V1. Regardless, Howards data on his old manifold is the best I have seen for a single wastegate manifold.

 

Lovely design. Do you reckon this will fit for RHD cars with the steering linkage in the way?

 

Impressive and great job translating that design to be 3D printed.

A big advantage of 3D printing is the ease of making changes. It would be nice to see an improvement of the flow to the wastegate with more of a radius since the wastegate is already mounted at a less than ideal <90* angle.

 

have recently made a few more changes to arrive at OPTIMUM configuration. hopefully be in production soon... Made in USA.

 

first run in 2013 and finalized for production today. you are looking at a 3D prototype of what will be the CPR production manifold. there's way more engineering than meets the eye.

i may have pricing and availability within the week.

i did a 3rd gear pull w my original welded manifold yesterday which is still running very well. only 35% exhaust backpressure. 21.9 psi versus 29.6. the low EMAP is even more impressive given that the wastegate is plumbed into the downpipe and i have a 3 inch exhaust.

591/405 tq at just 7643. more boost than backpressure until 6563. 24 psi makes 650. Garrett G40-1150. i expect the SolidWorks iteration to perform even better in all respects.

considering that BW estimates it takes around 100 hp to drive a compressor at 80 pounds of air the 35% cost V boost is a really good number. less backpressure, less polluted charge air.

here's the run from yesterday:





.

 

say hello to CPR manifold one. machine work complete. journeying over to Carter Thompson at High Pressure Performance tomorrow to get fitted to my downpipe and IC. i am excited about the optimized configuration of the interior passages. the change from round to semi rectangular literally continues even thru the 5/8 flange. check out the wastegate exit. huge... 57 mm. the wastegate piston is 60 mm/ 2.36 inches in diameter. 4.38 square inches of wastegate!




built like the Yamoto at 13.2 pounds, well O K shy about 72,000 tons. ASTM-A351 SS heat treated to 185 BNH. i hope to be back on the road in 10 days. since i have done more than 50 3rd gear runs fully instrumented w my steel manifold it will be interesting to see the numbers. after a few checks with Carter tomorrow i expect production to start Monday. in Alabama.

 

I like the equal length design, I hope it works well. There are lots of experienced people online claiming that the wastegate angle should be about 45 degrees, and 90+ degrees angles like this manifold should be avoided for best power and accurate boost control. One example is this wastegate install guide from Garrett. https://www.garrettmotion.com/wp-con...ll_Guide-1.pdf . I understand the wastegate itself may need to be that angle because of packaging, but had you considered adding curvature to the wastegate pipe so it can have a better merge angle with the two exhaust primary pipes?


After seeing the video below, my pie-in-the-sky dream exhaust manifold would include some anti-reversion features as well.

 

With a large enough gate it shouldn't matter even on bad pump fuel target boost.

Only small critique would be given it is a common gate you should only need to sample one runner for EMP reducing the cross pulse loss area. The individual EGT probes and wideband are better for identifying misses or compression issues than reading averaged EMP tea leaves.

 

" the wastegate angle should be about 45 degrees, and 90+ degrees angles like this manifold should be avoided for best power and accurate boost control."

wastegate configuration is about finding a balance between control while reducing the flow penalty.

without any question placing the WG port more directly in the path of the flow increases control.

without any question placing the WG port more directly in the path of the flow decreases flow to the turbine.

here are a couple of trainwrecks to make the point.


:

clearly way too biased towards the WG.
.
the CPR WG location purposely favors flow to the turbine.

there are other important negative factors relating to the WG that i see on many manifolds. ideally we are wanting to efficiently transfer the energy/flow from the explosion to the turbine wheel. in that process the flow must be turned. in a tube, all of the turning is done by the outside wall of the turn.


. the last thing you want to do is locate a hole in the tube for the WG on an outside wall.


another prevalent WG negative is the remote WG.





remote position WGs exist primarily because of packaging considerations. WG efficacy is diluted by the significant additional runner volume, bends and wall drag. in addition, typically the fragile diaphragm in the wastegate is closer to the very hot downpipe and runners.

my WG position places the critical end of the WG away from the heat and in the ambient airstream. it was nice of Mazda to provide an accommodating space in the subframe.


lots of good theory here but how does my my WG actually control boost?

turning off the boost control and running on two Tial red springs

Borg Warner SX-E 62 1.0 hotside 14.2 psi. recirculated WG into a 3 inch exhaust 2016



EFR 9180 off the same springs 15.2 psi


i haven't experimented w softer springs.

"With a large enough gate it shouldn't matter" WG valve size IS a big part of the WG efficacy. the Tial V60 sports a, wait for it, 60 mm valve.

4.38 square inches of WG valve area. two 44 mm wastegates have only 7% more valve area, along with another set of V bands. loads of plumbing and more dollars. i love the real pro race quality of Tial. i have been running both the same WG and the same untouched welded steel manifold since 2013.

for those interested in further info i suggest you read the "System Design Section" of my site.

SYSTEM DESIGN

 

just to clarify, i don't mean to suggest that other manifolds won't work. i have always been infected by racer-itus and it has almost always worked for me. for many, just doing the Turblown setup is an easy solution. for others, looking to optimize their setup my manifold is an answer.

 

Are you able to plumb the wastegate exhaust back into the downpipe?

 

"Are you able to plumb the wastegate exhaust back into the downpipe?"

yes and it is beautiful. not one bend from the WG and a happy joining angle to the DP.

here is a very dated picture that lays it out

l

 

Do you run your radiator really high or really low?

 

radiator is in stock location. normal coolant temp 155 F

 

Normal coolant temp of 155? How so? Also do you alway run a fan for the intercooler? Ive thought about adding one to my mount for low speed and traffic situations.

 

here's a recent 7 minute log showing ECT. driving around/warmup and a third gear pull. max temp was 151 F/66 C. prior to making 3 coolant system changes my driving around was the typical 189/87. i used to raise the hood after a drive. to be greeted w a blast of hot air, similar to opening the oven after cooking a pizza. .that's why i louvered my hood.

after making 3 changes i went for a drive and couldn't believe my digital dash. really couldn't believe. i raised the hood and was greeted by nothing. i grabbed my heat gun and all i could get was 150 F. that was 7 years ago. normal to me is 67 C.

the three items are: a Mishimoto 153 F thermostat, a FFE idler pulley and a Rick Engman water pump. the ECT sensor has not been changed nor have any calibrations. i have had 2 motors in the 7 years. i sold my motor (which was working great) to buy a new Mazda motor which has been in my car for 3 years. two motors, same temps.

back when i was (road) racing w piston motors i did an engine dyno coolant temp test and found 195 made the best power. so i am running coolish and am very happy to make the trade as i think heat is cumulative as to engine degradation. cool is always good on an FD.

here's Rick's masterpiece:



i didn't have the IC fans on for the above log. i seem to always forget to turn them on... will fix that
.

 

Glad to see this come to fruition, the manifold design has been very well optimized for the fitment space on an FD3. Unfortunately the fitment doesn’t work on some chassis’, such as the RX8. 😭
.

 

Any chance there will be a IWG version of this manifold available too? Everything staying the same but with no external wastegate location.

 

I would think any decent radiator and proper ducting could keep the water temps at 150*F when Cruising at 4500rpm without much load (which does not put a ton of heat into the system). I would be interested to see if the stock water pump could accomplish that as well with a 153*F thermostat.

 

"I would think any decent radiator and proper ducting could keep the water temps at 150*F when Cruising at 4500rpm without much load (which does not put a ton of heat into the system)."

totally understand, however prior to changing those 3 items my car was 87C cruising.

re doing the manifold with no WG... that would be easy. the key would be if the WG diaphragm, actuating rod, and flapper valve would fit. my guess is the flapper would possibly interfere w the ABS unit. just a guess.

 

What thermostat did you have before?

 

i don't recall