As you probably know, from (required) reading my "System Design Section" i am, and always have been, obsessed with system flow. I grew up in the NA world where you only have atmospheric pressure helping you to make power.
The turbo world is incredibly sloppy. Hang on a turbo and slam some air into the motor. The only reason my low drag manifold exists is because there were no other good options.
A bold statement but backed up in the "System Design Section." Please read it carefully prior to this section.
I am currently running the prototype I created in 2013. It has no cracks and has never been re-welded.
I have never marketed my manifold however I have received a continuing interest in making it available. Fabrication tech has evolved since 2013. SolidWorks, along with 3D Printing and uprated casting techniques has enabled me to create an even better manifold. Prior to getting into the details permit me to share the bottom line:
Here are a couple of screenshots from my most recent 3rd gear run generated with my 2013 welded manifold.. Note screen one is 72 MPH at 4:44.617.
Here's a perfect example. Notice the setting is at zero smoothing. If it were set at a typical setting the lines would look smooth to the end of the run. It is all about combustion chamber pressure. As it rises additional demands are placed on the charge air. If it is partially polluted with exhaust from exhaust system restriction misfires occur. You may remember that my manifold had more BOOST than backpressure until 6500 rpm. Zero intake pollution. More power and a safety margin versus knock.
Optimal engineering matters.
The turbo manifold is a key piece of the knock mitigation puzzle in that by optimized engineering EMAP can be reduced leading to less charge air heating.
Clearly it is very important to engineer low back pressure. Since it takes around 100 horsepower to drive the turbo to the 500 hp area there will be some pressure but it is important to reduce that pressure as much as possible. Minimal runner volume, minimal bends, minimal wastegate port interference and laminar flow shine on the CPR Low Drag manifold.
Not only low drag but equal flow between the front and rear runners. Note on the second screenshot my front EGT was 1714.1 and the rear was 1717.3!
As they say on TV, "But there's more."
The second screen is the last tick at 100% throttle. 112 mph at 4:46.244. The next data point is at less than 100% throttle as i had to get out of the power due to the car starting to go sideways. 40 MPH in 1.63 seconds at 22 pounds of boost. 628 rwhp.
Take a look at the total package: CPR LOW DRAG MANIFOLD
Notice how the CPR huge 60 mm Tial wastegate (singular) ports are after the turn towards the turbo resulting in very low drag from the wastegate.
The balance between flow to the wastegate and to the engine is critical. Too much flow to the wastegate and power is unnecessarily lost. Too little and low boost control is difficult.
Most manifolds favor the wastegate over drive to the turbine. The CPR manifold favors drive to the turbine/power. If your objective to run less than 14 psi you might be better served with Elliot's internal wastegate setup. The CPR manifold shows zero boost creep even with a large turbo (EFR 9180/G40-1150) at 15 psi.
The CPR Low Drag Manifold is available with a turbo specific downpipe, Tial 60 mm wastegate and your choice of turbos. If you have a turbo I will provide a specific downpipe so you have a bolt in project. Various other items, such as an oil drain line are included. If you don't have a turbo, or want to upgrade, I recommend you give me a call. I handle Garrett and Borg Warner. Most anyone can sell you a turbo. Not anyone can provide you with helpful insight as to which turbo.
FYI, the turbo paradigm has changed. Don't be the last one to get on the old school train.
If you have an interest in the manifold system simply give me a call or send me an email or text. I look forward to speaking with you. I am now a vendor (again) on the RX7club.
Howard Coleman
262-339-3858 howracer@gmail.com
My manifold project partner is Carter Thompson.
His contributions have been essential and he is an all around awesome guy.
highpressureperformance@gmail.com
615-969-9337
You are looking at 22 exhaust manifold gaskets. And they all leak. If you have a single turbo manifold your exhaust gaskets are leaking. They all leak in the same exact places. 9 o'clock on the front and 3 o'clock in the rear... as in the picture.
Why the leak on all gaskets and why only in a certain area? An inspection of the manifold flange will show it is warped between the exhaust ports leading to leakage. While heat from the exhaust flow torches the manifold equally around the circumference of the port the metal cannot expand equally in the area between the ports. The expansion is stopped by the exhaust studs as well as the greater amount of material. This section expands away from the motor.
Here's the solution to exhaust leakage:
Finally, a proper FD turbo manifold constructed in modern stainless steel form. (before finish machining.)
Job one: LOW DRAG
MINIMAL BENDS
MINIMAL EQUAL RUNNER VOLUME
INVISABLE WASTEGATE
Thereby locating the turbine wheel as close to the explosive combustion power as possible with minimum drag between the two points.
Bends create drag. Of course the outer wall of any bend is most important as it does the work of turning the flow. It is especially important that the bend outer wall remain intact so it can make the turn un-interrupted.
I see many manifolds locating a wastegate port on the outside of a turn. Very very bad for flow. Great for increased drag and EMAP.
Really nice numbers but let's look closer.
At 72, 5183, 439 hp/459 torque we see 21.6 boost and only 14.1 EMAP/exhaust backpressure! There is more boost than backpressure until 6500 RPM! Finally, at 8047 back pressure is only 35% more than boost at over 8000 RPM and 600 rwhp.
Further making this exceptional is that the wastegate is blended into the downpipe AND the exhaust is 3 inch.
Exhaust backpressure (EMAP) is evil.
Our OE motors have overlap. Porting often increases overlap. Overlap is when both the intake and exhaust ports are open.
Restrictive turbo manifolds create significantly higher backpressure.
Mix backpressure with overlap and bad things (knock and pre-ignition) can happen. Exhaust gas can be 1700F and contains almost no oxygen. If you are making 17 psi boost and your exhaust back pressure is 25 or 30 psi it is probable that some of the scorching hot exhaust will pollute the cool charge air.
This dangerous degradation of the charge air WILL create misfires, at minimum, or detonation/knock/pre-ignition. All engines misfire, it is just a question of degree. Higher EMAP results in moving misfires closer to knock. Misfires are generally not evident from the driver's seat. Misfires are easily spotted on a dyno chart when zero smoothing is selected. You will see the power line change from being smooth to little squiggles to reflect loss of power. This will happen around peak torque which is the point of maximum cylinder pressure. It will continue to redline.
CPR LOW DRAG TURBO MANIFOLD