I'm trying to decide on wastegate configuration for my RX3 and would like input from anyone who's built similar setups.
Option 1: Single Large Gate with Divider
1x 50-60mm wastegate with divider design
Based on DMA manifold concept but with longer divider extending to valve seat like CPR
Option 2: Dual Small Gates
2x 38-40mm wastegates positioned near the exhaust flange
Similar to GleaseMan and Turblown FD manifolds (see reference images)
Option 3: Tee-Style Gates
Pipe tees after the first bend on each runner for 2x 38-40mm wastegate ports
Less wastegate priority but potentially better flowing
Would this placement work effectively?
My Current Thinking: Initially liked the DMA single-gate design for simplicity, but now leaning toward the tee-style gates. My main concern with the single large gate is flow disturbance being so close to the area reduction before the turbine inlet. However, I'm also not thrilled with the dual gate setup having the wastegates on the outside of the first bend. The pipe tee approach appeals to me because when the wastegates are closed, you get a nice reentrant curve that should flow much better than having the gate pocket on the outside of a bend.
Specific Questions:
What are the real-world pros/cons of each configuration?
How significant would flow disturbance be with the single large gate placement?
Has anyone tried the tee-style placement? Does it work well despite lower wastegate priority?
For rotary applications specifically, which setup preserves exhaust pulse energy better?
The car is just a street driven hotrod that might go to the drag strip and to the track on occasion. It has a Street Ported Cosmo 13B, an EFR9180 w/ 1.05AR and a Mr Enforcer Engineering Modular Intercooler. Fuel system is E85 compatible , but no flex sensor yet. Thinking about running ~17psi with the ability to turn it down to 10ish.
I went with Howard Colemans design. He has a lot of data on back pressure for larger turbos your size. It has one large single waste gate, which I like. Less hardware, lines, etc.
"10psi is low boost that will require high wastegate priority and generous wastegate sizing."
spot on
as mentioned by FDAuto, your turbo will call the tune as to wastegate ability and you have a big one. easily capable of 600+ rw rotary at 22 psi. if you had a GT3582r, yes, you could run 10.
as Blue T2 correctly points out by directing the flow to the wastegate rather than the turbo you would move the ball towards lower gated boost but you would be castrating the turbo. having owned an EFR 9180 for four years and having a proper manifold i can tell you that if you are going to put your foot down you will be looking at 450 minimum. and that might be low. you have a 650 rw rotary hp turbo. and it spools pretty well.
EDIT post nine contradicts my above statement... w just a change to a softer WG spring my manifold was making 350 at 12 psi w a 9180!
as to the drawing in post 4, it looks pretty. until you bolt on the TWO wastegates and then decide how to connect them to your DP.
further, TWO wastegates sounds pretty awesome compared to one wastegate.
until you look at the numbers;
valve area
one 60 mm 4.38 sq inches
one 50 mm 3.04
two 44 mm 4.71
two 40 mm 3.89
two 38 mm 3.51
Two 44s have only 7% more area than one 60. plus lots more V bands and piping into the DP. if you go w two they need to be 44s. two 40s will not properly manage a 9180.
just for the record, my manifold has a 100% linear shift from round to T4 that starts, literally on the outer edge of the engine flange and ends at the outer edge of the turbo flange. thank you SolidWorks. my partner in crime on the project just finished gluing the new cast manifold to my DP and IC so i should be up and running this week. generating data. i wouldn't sell anything without the data.
my cast manifold may be good or bad... if it is good, it is coming to a theatre near you. .
Thanks for the great feedback everyone. This has really helped narrow my focus to either a single 60mm or dual 44mm wastegate setup.
@Blue T2 - Really appreciate the tip on moving the wastegates closer to the turbo for better boost control. That makes a lot of sense regarding exhaust backpressure fighting the wastegate at higher RPMs when positioned too close to the ports.
@Howard Coleman - Your valve area calculations really put things in perspective. The fact that dual 44s only give 7% more area than a single 60mm (4.71 vs 4.38 sq in) while adding significant complexity with extra V-bands and downpipe routing is eye-opening. Definitely leaning toward keeping things simple if the performance difference is that minimal.
Looks like I need to get a bit closer to finalizing my routing layout and identifying clearance obstacles before I can make the final call on packaging (single vs dual WG).
Looking forward to hearing about your cast manifold results Howard - always interested in real-world data vs theory!
at first glance you might be wondering why you are looking at an 12 psi boost chart.
a few years ago i did a small production run of my welded CPR manifold.
an engine customer is running one with an EFR 9180. a few days ago he decided that running in the high 30s probably wasn't a great idea w re to longevity so he decided to do a bit of wastegate spring swapping. the log above is the result.
12 PSI on an EFR 9180!
i have always run two red springs and w my 9180 or the G40. w the boost controller off i generally see 16/17. i have often wondered what my boost would be w less spring.
question answered.. to me that's a big WOW.
the CPR manifold was designed for max flow with the exhaust flow biased towards the turbo not the wastegate.
any article written on wastegate positioning guides you to positioning it in the flow. to the extent you do that you lose flow to the turbine.
the above log proves you can have effective wastegating while not interrupting the main event... power to the turbo.
the point being, whether you are running a small or large turbo you can dial in pretty much any boost level you want w my manifold.
it will be interesting to see how much power he can make w just the one small spring..
