Has any one installed the new down pipe from TTi? Not sure of the details but I understand it is larger in circunference and increases boost. Also deos anyone know the cost?

Thanks
The Big Dog

 

We have done a few sets of them. We are doing another car now with them also. I think they are just under 1k.

 

On C5's? Older turbos? What are the results?

 

Sorry no that was all on C6's

 

I should be receiving mine soon. I plan to post pics, etc in my build thread.

 

I dont know of anyone that has done these on the C5s. I am curious to what 3 inch exhaust setup they ended up going with.

 

Just so its clear a larger downpipe will not increase your boost.

 

Maybe if less restriction = boost creep?

 

I thought the boost creep issue was the gates and BOVs.

Would it make as much or more power on the same boost level given the added flow?

 

Boost creep is caused by having to much pressure before the turbine. This would be caused by several things, poor exhaust design, undersized wastegate, turbine size and a/r etc. Having a larger downpipe changes the pressure difference from the inlet to the outlet of the turbine. Larger downpipe increases the efficiency and decreases spool up time.

 

There was a thread in the C6 section where Fran discussed dealing with it. He said it creeped with 3" open DP. It makes sense, due to the external WG. When I changed mufflers once it affected the boost alot. I will be glad to give a before & after review if someone donates the DP.

 

What is your plan as far as the 3 inch DPs all the way to the rear of the car? You have a 3 inch exhaust setup already?

 

Wastegate location could be a part of that of that creep problem. Where you running just off the wastegate's when you switched mufflers?

 

Yes, running off the WG springs when a muffler swap resulted in 2-3psi.

 

Is that really an issue for those who have an ABC?

 

Beats me, I'd have to swap mufflers again to find out. I'm not making an issue, just giving an example how restriction changes on the exhaust side can affect boost.

 

If that was the only changes the wheel speed increased. Turbos spin because of the pressure differnce from high to low. since the only change to the setup was muffler or downpipes this would mean the pressure was now lower post turbine and the exhaust gasses could now flow faster causing an increase in wheel speed. I dont think this would be considered boost creep. I always thought of boost creep as the wastegate can no longer bleed off enough volume to maintain a desiered boost level. I dont think thats what you have going in here.

I know a guy that is planing on getting some of those BW EFR turbos for a build. They have provisions for wheel speed sensors. I would love to do some test with wheel speed and exhaust pressure before/after the turbine. Would love to see what would happen with some cam swaps aswell but that may be out of the question on that build lol. Cant imagine the truth that would come out of that. I want to test the difference that cams make in turbo setups aswell because I think there is a lot of bs flying around about it. I think the key factor in a turbo cam is the exhuast side because of the difference in manifold design. I dont think a manifold/log vs header desgin have the same pressure ratio therefore the split should be differnt for the setups. Will find out soon enough though as I have recently purchased a kit with a header design and know a guy building a manifold kit and both will be tuned by the same guy.