user_name

I would like to hear from other TTIx owners about their setup and if they have boost creep issues. I have a 347 with twin PTE 6265 billet turbos with the CEA wheel and TTI 3" downpipes into a 3" X pipe and an XS Power 2.5" catback. I cannot make less than 16-17psi. It was 22psi when I had straight 3" exhaust. TTi confirmed that this is a known issue with these particular turbos and 2" downpipes on their kit. The only solution other than re-engineering the kit for better wastegate placement is to restrict the exhaust or intake more. This gives you slower spool.

I'm not happy with the setup, and I want to make the right change. The car makes 950rwhp as it is, and I'm not looking to make more. I'm considering going to the turbonetics turbos that are the base option on the kit, but I can't find anyone running these with 3" downpipes to comment on boost control.

Yes, the boost controller and lines are hooked up correctly. It is mechanical issue. The exhaust housings used on this kit are really designed for internally gated turbos, and they do not divert enough air to the wastegates to slow down the wheel and reduce boost.

Frans96ss

What boost controller are you using?

We use Eboost 2's on our TT manual transmissions stuff... Here is 2 graphs from diff cars we did.

What WG springs do you have? We can controller then down to like 10PSI but no less with a 3.5PSI spring

Chris Stewart

I don't fully understand your issue, but have been happy with mine running Turbonetics and 2.5" DP. I ran 7psi at the start (off the gates) and up to 23psi so far (manual pressure regulator), making up to 920rwhp thru an A4 on a Mustang dyno. You have a 6 speed, 6265 and 3" DP but only 30hp more? I was looking at the 6265 upgrade for more power, so I'm also confused by your results. We could trade turbos if you want.

user_name

I am also running the eb2. I have tried 8psi springs on up to 13 psi. It makes no difference at all.

Fran, what is the exhaust setup and are these 6265's with the cea wheel that has been out only about a year?

950 is at 22psi and a conservative tune. It would do 1100+, but I am not interested in the fate all the 1k+ rwhp vettes i know of see. More shop time than street or track...lol

Corvette_c6_AD

I would like to hear from other TTIx owners about their setup and if they have boost creep issues. I have a 347 with twin PTE 6265 billet turbos with the CEA wheel and TTI 3" downpipes into a 3" X pipe and an XS Power 2.5" catback. I cannot make less than 16-17psi. It was 22psi when I had straight 3" exhaust. TTi confirmed that this is a known issue with these particular turbos and 2" downpipes on their kit. The only solution other than re-engineering the kit for better wastegate placement is to restrict the exhaust or intake more. This gives you slower spool.

I'm not happy with the setup, and I want to make the right change. The car makes 950rwhp as it is, and I'm not looking to make more. I'm considering going to the turbonetics turbos that are the base option on the kit, but I can't find anyone running these with 3" downpipes to comment on boost control.

Yes, the boost controller and lines are hooked up correctly. It is mechanical issue. The exhaust housings used on this kit are really designed for internally gated turbos, and they do not divert enough air to the wastegates to slow down the wheel and reduce boost.





sorry to hear that. I have faced the same problem and this is what i have done.

This is before porting the turbine + dyno sheet




And this is when i did the porting to turbine housing, i also changed the wastegate to 44mm and left wastegate outlet to atmosphere!!






And i did a tricky porting to the turbine if you are interesting to do porting to your turbos, just let me know

user_name

That is very interesting. I have been down this road also. It looks like you ported the housing where you saw carbon build up. I did the same thing, but my results were nothing like yours. Any tips?

Corvette_c6_AD

Yes correct. Did you port inside the turbine hosing? If yes, then you have to change the wastegate to 44mm as my tuner recommended me while i was doing porting to my turbine hosing. Good luck!

user_name

Yes I did. I just opened them up though to match the port on the downpipe which already matched the 38mm wastegate size. I don't understand why this fixed the issue for you if you didn't replace that piping on the downpipe to the wg also.

Corvette_c6_AD

Try to open the wastegate to atmosphere instead of going back to downpipes.

user_name

I have also done this...grrr

Tiago

44mm gate will deffinately help if you currently have a 38mm.

user_name

How will this help if the opening on the housing and the piping leading to the gate are only 38mm? I would think those would be a bottleneck.

Vince99FRC

I cant go any lower than 12.5psi. I have tried different springs.

Tiago

port housing and replace the WG tubing with 1.75" tubing.

slow ride

Have you tried it with the ported gate holes, returning wastgate back to the exhaust and running the catback? I'm pretty sure when you ported the gate holes you did the external dump at the same time if I remember correct. Not sure how easy it would be or if you would feel like trying this after going to external dump without lots of welding, etc, but it might help. I always had better control of boost with the gate routed back into the exhaust back in my dsm days.

Corvette_c6_AD

user_name

Check the last picture for the turbine housing in the below link. I did the same thing but i made it more wider then the one in the picture. This is to force the air to go inside the pipe to wastegate. I hope you understand what i'm writing because my english is weak.

http://forum.miata.net/vb/showthread.php?t=349841

slow ride

I think He or Geroge from ttix said the porting was angled towards the wastgate path already. I've never seen pictures from the inside of the volute/inlet flange.

Have you tried to run just off spring pressure? Just run the boost ref. to the side port on the gates with the top open and no electronics.

user_name

I definitely am not up for too much experimenting. I'd rather make a drastic change and do this once. I'm definitely sick of this issue. This kit is NOT easy to work on. I have the drivetrain out currently though and had to take the DP's off.

Slow Ride, I did do the venting to atmosphere and porting at the same time. You may be right on the venting, but I doubt it is going to drop boost 50% 1 way or the other. That's what I am wanting it to do basically.

I've set the eb2 to 0 SP and 0 GP. The solenoid does not click when you do this, and you are on spring pressure. SP goes from 0-100, and the boost increases linearly when I make these changes which tells me it is working fine. I've tried a few springs. 13psi being the highest which is in there now. It makes zero difference on the low end. I just have to up the SP more with the smaller spring to get high boost.

Corvette_c6_AD, your english is perfectly fine. I see what you are saying. I think I was worried about going to thin on the housing and did not do this when porting. If I'm going to do it again I'll need to look up some kind of guidelines for wall thickness on there.

Turbo-Geist

It looks like this is the closest that you have gotten to a possible solution. I looked at the pictures in the link and they remind me a lot of a reverse cathedral port with the way the channel works to smooth out the short side radius. The exhaust flow wants to deflect or separate off the short side wall and mix with the rest of the flow when you have a tight short side radius. Basically they compete with each other to get out of the opening in the housing. The internal trench allows you to flatten the short side radius and give some room for everything to exit.

Now, the only other question is whether the 38mm wastegates will be big enough? When you try to get down to 12 psi, it will mean that you are diverting even more exhaust through the wastegate. If you can get it out of the turbine housing but not through the 38mm wg, that will be your next bottleneck.

Your best shot at solving this will probably be to do the correct porting as well as 1.75" tubing to a 44mm wg if there is room to fit everything. Unfortunately, that means spending more money.

Corvette_c6_AD: Big props for bringing some real tech back to the FI section.

Corvette_c6_AD

Anytime Turbo-Geist

I have fitted 44mm wastegate with no problems and i did not change the wastegate pipe.