Whiled overboost at 4k

[gavinc69]

Hi guys

Car's been off the road for 5 months so had no updates until now.

An Omex 710 ECU has been installed with all new wiring etc etc by a local specialist to replace the Microsquirt that I installed which just was never quite 100%. Now the car is setup and runs fine with the new ECU, but on the dyno as it pass's 4000 rpm the boost spikes and keeps rising to 1bar +

Hardware :
3.0 SC motor
3.0 heads (ported)
RS cut valves
993 Cams
3.2 intake manifold
Full bar IC
Tial 46mm WG with 0.5bar spring
OBX headers
K27-7200
BOV
Omex 710 ECU with coil packs


I have gone through various configurations and upgraded the hardware to the above spec over the last 3+ years and have never had this issue before, yeah it would creep a bit, but to 0.6 or 0.7.

The guys installing the new ECU and wiring have gone over the setup, removed the WG and checked it, that's all fine.

Has any one got any ideas as I've run out ans the guys installing are starting to scratch there heads

Thanks

Ah, best put a pic

[quattrorunner]

OBX HEADERS and better response from the new software. The headers are the problem.
I too am having tis issue, my car has a new larger displacement engine and larger turbo on the same headers. I put a .5 bar spring in to quell some clutch issues my new engine gave me and my Porsche waste gate attached to the OBX headers creeps up to 1 bar+. My intercooler and tune can deal with it as long as the clutch can hold it. But I'd rather have a better header design..

[gavinc69]

Thanks for the quick reply.

I had ready a few older posts about Schnell headers causing a similar issue and wondered if that was the case.

So I'm thinking if the WG pipe is cut from the headers where is joins. The hole can be opened up a bit and bigger I.D pipe could be welded in place and also shorter so the WG is a lot closer to the turbo.
The guy doing the work did say the current WG pipe is a smaller I.D than that of the Tial WG.

Do you think that would do the trick? That's what seemed to be suggested regarding the Schnell headers.

What have you got in mind to do with your setup?

I just can't stretch to new headers after all the other work that's just been done.

[dos531]

Certainly sounds like boost creep due to header design. I get it on my B&B headers as well. If I set it for 0.8 I get 1 bar by redline. Luckily It's set for 1.1 so no issues. Shooting for such a low number is going to be challenging with that setup.

[Rodsrsr]

Check the vent tube on the tial wastegate. If its like mine its not connected to anything and venting to atmosphere. I experienced an overboost issue once and turns out there was a bunch of dirt clogging the vent fitting. Cleaned the fitting and re-directed more upwards and all is good. Probably should check it again now that I think of it. Okay I just re-read and saw that you guys checked the wastegate. I got nothing. lol. Hope you get it sorted and please update. I run a similar setup.

[gavinc69]

If I'm not buying new headers looks like the only option is to mod the ones I have.

Option 1.
Cut the current WG pipe off, open up the hole in the collector that feeds to the WG and install a larger I.D WG pipe thats the same I.D as the WG which its currently not and make the pipe shorter.

Option 2. Cut the current WG pipe off and fill the hole. Then run a pipe from each headers side just before the collector and merge them before the WG.

Option 2 does look to be better and I see how if would function better also but seeing as most people have the sort of stock layout with the WG pipe off the collector I'm sure option 1 should work. Plus it would be quicker, easier and cheaper.

Option 2 pics.....

[quattrorunner]

I really like option 2.

[IMR-Merlin]

are you able to run boost control from the ECU? Why not run a EBOV to pull the spike out?

[dos531]

You could also run a separate smaller wastegate for each bank. Less plumbing that way, and looks clean. Just plug the current hole and weld a v-band on each bank.

Originally Posted by gavinc69

If I'm not buying new headers looks like the only option is to mod the ones I have.

Option 1.
Cut the current WG pipe off, open up the hole in the collector that feeds to the WG and install a larger I.D WG pipe thats the same I.D as the WG which its currently not and make the pipe shorter.

Option 2. Cut the current WG pipe off and fill the hole. Then run a pipe from each headers side just before the collector and merge them before the WG.

Option 2 does look to be better and I see how if would function better also but seeing as most people have the sort of stock layout with the WG pipe off the collector I'm sure option 1 should work. Plus it would be quicker, easier and cheaper.

Option 2 pics.....

[pkabush]

Originally Posted by dos531

You could also run a separate smaller wastegate for each bank. Less plumbing that way, and looks clean. Just plug the current hole and weld a v-band on each bank.

I like this idea best

[smurfbus]

I did just that last summer. Its sounds like hell fire with no dump pipes after those two turbosmart 38 wg. First time I thought I had nailed the heads as it reminds of really bad knocking.

[gavinc69]

This looks like the issue.................




So with the wastegate pipe cut off you can easily see the crappy job that OBX did when making the headers.

Its all been cleaned out and the wastegate pipe reduced in length........





Hopefully this should do the job
Will keep you all updated after the next dyno run.

[gavinc69]

Quick update.
The exhaust mod fixed the problem and it holds .055 bar to 6.5k

[Tippy]

Originally Posted by gavinc69

This looks like the issue.................

Holy shet! What in tarnation?!?! No wonder the creep....