maxpro

I have a question for the group, what turbo manifold are people running? How much PSI are you able to run with it? Do you have any issues of backpressure restrictions? If so what PSI? I would like to keep the powersteering pump on the car. I'm currently running a FM log manifold and it is causing backpressure issues and need to find something else that will allow me to run the Garrett GT3071R (modified to external WG ). https://www.atpturbo.com/mm5/merchan...archcatcount=1
02 NB with a GT3071R, Skunk2 intake, Keegen ported head & cams, ID 1050 cc, lots of other stuff.
I want to be able to run 18 to 20 psi.

Thanks in advance

Max

WigglingWaffles

If you want more out of a cast manifold than fm log, kraken

maxpro

All that I have seen with the kraken is either bottom mount and no PS or side mount for internal WG. I guess I could then fab for my external WG.

codrus

Have you measured the backpressure coming from the FM manifold?

--Ian

maxpro

Ian, I'm not sure how to measure the backpressure on the FM manifold. Suggestions?

curly

iTrader: (25)

Your original post made it sound like you already had. What are the “back pressure issues” you’re experiencing? We’re asking because I’m fairly certain there’s plenty of people that have ran 18-20psi on an FM manifold and a 3071R.

maxpro

It has a Keegen ported head with 2mm larger valves. With a 7 lb spring the car pulls strong through 7800 rpm making good power. I changed the spring to a 14 lbs spring and the car pulls strong till about 6000 rpm or 6200 rpm and seems to caugh right there. It is an external WG and with the internal WG the engine with the WG locked wide open would make 11.8 psi. boost creep which is the reason to go to the external WG. I think the head is flowing more than the manifold can handle. All suggestions are welcome.

codrus

What kind of exhaust do you have on the car? If you are experiencing backpressure problems, then it is more likely caused by the exhaust after the turbo than by an FM manifold in front of it.

I would start with the exhaust. Get an O2 sensor plug and some copper tubing, drill a hole in the plug the same size as the tubing, and insert it. Install the plug into an O2 sensor bung in the downpipe as close to the turbine outlet as possible. Run 6-8 feet of the tubing to some vacuum line and then to a pressure gauge. Go for a drive and log the pressure that you see at various RPM/boost levels. You want this value to be as low as possible, not more than a few psi at most.

If it's low then do something similar to the above, but using holes in the manifold. Do you have an EGT sender in the collector, right before the turbine inlet? If so, that's a great place to measure turbine inlet pressure in the same fashion. If you want to compare turbine inlet pressure to head outlet pressure, you can use the EGR port at the back of the head.

If you're handy with electronics, an even better approach is to use a pressure sensor hooked to an aux input on the ECU, then you can log it all electronically and generate graphs like this:


I ran my car up to about 280 KPA MAP with an FM log manifold and a GTX2863R using an EWG turbine housing. I never bothered to check pressures in the EGR port because I never saw any signs of the manifold being a problem -- I was seeing turbine inlet pressures lower than compressor outlet pressures for a good chunk of the RPM band.

Lots more pics and graphs in my build thread (look around post #400).

--Ian

maxpro

Ian,

It is the FM 3" from the turbo all the way back. Thanks for the thread and how to do some testing. I now have some testing to do.

codrus

Do you have the FM cat? That was causing some substantial restrictions in my car.

--Ian

maxpro

Yes, I do. Something else to look at.

Gee Emm

Don't know about FM cats, but cats generally can break up and create blockages. Ask me how I know :-(

der_vierte

maybe change that out for a 5" 100 cell cat, if your state allows, these can support over 600hp and are pretty much no restriction

codrus

When I bought my FM 3" exhaust (2010) it used a metal core cat which flowed extremely well. After a few years of track (ab)use it started coming apart -- no blockage, but a good chunk of the back of it was missing. It turned out that FM had been having a lot of failures of the metal core ones and was now selling ceramic core cats which did not flow nearly as well as the metal ones.

--Ian

maxpro

Update on the issue of back pressure. I removed the Cat and it was perfectly clean. I thought then it might be the exhaust muffler. I removed it and took the car for a drive (very loud) and my back pressure issue was still present. After some deep thought, I decided to retard the exhaust cam by 2 degrees. I reinstalled the muffler and took it for a drive and the issue was almost non existant. I made another adjustment and the exhaust is retarted by 3 1/2 degrees and the problem has been resolved. What I failed to mention is this entire problem solving mission was the car has a Keegen ported head with Keegen ground cams. The exhaust valves are opening earlier and with 7 lbs of boost it runs fine and pulls hard to about 7800 rpm. With a 14 lbs spring the car would stutter at about 6200 rpm. Now with the 14 lbs spring in the WG and the exhaust cam retared 3 1/2 degrees the car pulls hard with no issue to 8000 rpm. Thank all of you that made suggestions and areas for me to look into. On to the next area to work on the car. I have to make or modify the turbo heat shield to accept the external Wastegate to protect the brake reservoir.

SpongeBob

Yeah if you are willing to fab something for the EWG, then I also recommend Kraken.