Turbo Boost Creep Creeping T25 14B 16G [Merged]

[Tecni]

did you happen to mess with the dump? Are you venting to atmosphere?

 

[90tsidude]

the all ive seen in this thread was a combo of the one i posted and this one. and yea i have 20 posts because im spending more time under my hood rather than in front of my computer and thank you kenamond! i order porting bits ill be grinding in no time. and ive taken the WGA off and i still creep. but yea when i get things hot i don't creep.

 

[kenamond]

the all ive seen in this thread was a combo of the one i posted and this one. and yea i have 20 posts because im spending more time under my hood rather than in front of my computer and thank you kenamond! i order porting bits ill be grinding in no time. and ive taken the WGA off and i still creep. but yea when i get things hot i don't creep.

You're welcome. But please don't be insulting people in other threads that you hijack. nfernotalon has been actively trying different things on his car. This Turbonetics VBC is kind of a curve ball, and we're all learning from the experience, so folks have the heads under hoods, and folks are learning things they did not know as a result (and I have a bunch of ideas as a result). I would certainly spend more time under my hood, but I can't afford to buy something that gives me a reason. Ask questions, help out, be nice, and have fun.

 

[nfernotalon]

the all ive seen in this thread was a combo of the one i posted and this one. and yea i have 20 posts because im spending more time under my hood rather than in front of my computer and thank you kenamond! i order porting bits ill be grinding in no time. and ive taken the WGA off and i still creep. but yea when i get things hot i don't creep.

Well if were comparing hours under the hood to posts... I would have about a million posts, you have no idea how much time ive spent inside my car, outside, behind and under it... Way too much time on my car, but I dont mind i love working on my car

 

[twotonetsi]

i have a t28 from forced performance w/ ported 2g mani/02 house and 3" thermal turboback. it is this exact problem to a T. all is well until 4k when she starts spoilin to high hell! i am not readyto see 20+psi. i have tryed the peepers wga arm. lil to no help here. tryed the "no actuator" pulls with creepy results. i am resorting to porting before caveing to an ext wg. i deserately need to know the factory t25 and t28 wg flapper diameter size or wut new size to go with. i have been lookin for this answer for 2 weeks now with no luck. i need the car desperatly and i would love to have a new flapper in my hand when the unit comes off the car to make down time as limited as poss. im hopin to port then drive in 2-3 days max. anyone have one lyin round they can measure for me? thanks

 

[Mr Peepers]

i have a t28 from forced performance w/ ported 2g mani/02 house and 3" thermal turboback. it is this exact problem to a T. all is well until 4k when she starts spoilin to high hell! i am not readyto see 20+psi. i have tryed the peepers wga arm. lil to no help here. tryed the "no actuator" pulls with creepy results. i am resorting to porting before caveing to an ext wg. i deserately need to know the factory t25 and t28 wg flapper diameter size or wut new size to go with. i have been lookin for this answer for 2 weeks now with no luck. i need the car desperatly and i would love to have a new flapper in my hand when the unit comes off the car to make down time as limited as poss. im hopin to port then drive in 2-3 days max. anyone have one lyin round they can measure for me? thanks

I've only modified TD05H WGA's for people, and the t28 uses a Garret style actuator. If you did it yourself(before the article was made), it is important to know that it's much more than just making the arm adjustable.

If unhooking the WGA from the flapper arm still results in creep, it means the WG passage is the problem. Porting for boost creep or going external are about the only solutions besides a more restrictive exhaust. I would be hesitant in putting a larger flapper on since they are likely to blow open(drop psi by redline) at higher boost pressures down the road. If you do put one on, be sure to enlarge the WG hole so it matches the new flapper, yet still seals when the flapper is closed(very important).

 

[kenamond]

i have a t28 from forced performance w/ ported 2g mani/02 house and 3" thermal turboback. it is this exact problem to a T. all is well until 4k when she starts spoilin to high hell! i am not readyto see 20+psi. i have tryed the peepers wga arm. lil to no help here. tryed the "no actuator" pulls with creepy results. i am resorting to porting before caveing to an ext wg. i deserately need to know the factory t25 and t28 wg flapper diameter size or wut new size to go with. i have been lookin for this answer for 2 weeks now with no luck. i need the car desperatly and i would love to have a new flapper in my hand when the unit comes off the car to make down time as limited as poss. im hopin to port then drive in 2-3 days max. anyone have one lyin round they can measure for me? thanks

You can also go with an external wastegate mounted on a tubular O2 housing with the dump going back into the exhaust (unless you want LOUD). The flapper has to be removed, and then you can port the WG hole much larger. I think that's better than an external WG mounted on the #1 runner of the mani.

 

[twotonetsi]

yeah i agree. i would really like to keep it internal. i have researched for weeks here n that is my only option. im glad u responded peepers. i was tryin to respond to ## original thread and had trouble. AWSOME JOB! the custom actuator is a great idea! it worked very well for me on alot of cars i have delt with. i made 4 so far successfully. just need a lil more then what this wg hole on this T28 can offer. so did anyone have a t25 or t28 layin around that they could measure the wg flapper door and hole diameters for me? thanks for the help guys.

 

[twotonetsi]

any body know?

 

[kenamond]

any body know?

I'll dig up my T25 and measure it today. Stay tuned.

 

[Mr Peepers]

Miata Turbo Forum - Home of the turbo Mazda Miata.

I found this pic on the turbomiata forums(no reason, I bet it'd be fun as hell though)

Use username:mrpeepers
password: dsmtuners

to veiw it.

It *seems* like the t28 flapper is larger in the pic; they were saying it as well. I don't know for sure but I'm trying to get someone to measure the flapper on their t28 today. BTW the t28 in the pic straight from FP. My friends is a "normal" t28, not a bigt28 killa etc.

EDIT: After some more searching around, I'm seeing 32.5mm for the flapper diameter.

 

[Mr Peepers]

So, I took apart a t25 and t28(not the"bigt28," it was from gpopshop) tonight.

Sure enough, the flapper was 32.5mm in diameter on both. The turbine inlet and outlet were the same diameter as well. I would have said it's the same turbine housing if there weren't slightly different numbers cast into it; the t25 had .45 a/r while the t28 had a .49. As far as I could tell, the same size turbine wheel too.

There is a good amount of material that could be removed from the wastegate hole to better match the flapper, and I believe this would help your creep issues the most. The WG hole is about the size of a quarter, or 24-25mm, compared to the ~33mm flapper.

The flapper in it now gets hung up on the side of the wall if you open it too far, and I don't see you being able to put anything larger than a 34mm flapper in; which is pretty much pointless. It's just machined that close.

My suggestion if the FP turbine housing is the same/similar:
Take the turbo off(or just the turbine housing with the CHRA still on the car, difficult with t2's) and enlarge the WG hole to fit the flapper. Still leave some overlap though, about the thickness of a nickel all the way around(~1/16"/2mm). Do this with the turbine housing off from the turbo, and be sure to remove any chips before assembly of course.

NOTE: A little hint for anyone disassembling a t25 or t28, the compressor nut COMES OFF CLOCKWISE aka not the normal way. A 14b or 16g on the other hand comes off lefty loosey righty tighty

 

[twotonetsi]

gotcha, huge help. thanks!

 

[silver bullit]

boost creep is very common with factory internally gated turbo's, or all internally gated turbo's for that matter.

especially when trying to run lower boost pressures, upgrade to a externally gated turbo, a well designed tubular manifold and a 44mm wg and you should have less troubles running lower boost pressures.

This is your answer here...

 

[turboAWDfanatic]

Also, check these threads out
http://www.dsmtuners.com/forums/art...boost-creep-modified-wga-peepers-mod-how.html
http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html

One thing to remember, everybody mentions "ported O2 housing" when talking about creep. To elminate creep, you have to get an O2 housing with a BIG wastegate tube, and a not-so-ported main exhaust part. If you open up the portion of the housing that the turbo flows through, you're just increasing chances of creep. Unless you get an external dump or an external gate, of course.

 

[twotonetsi]

externally wastegate this lil wee baby ass turbo? nah im ight bullit. ul never need ext wg on these lil 16g and t28. just a good portjob!

 

[zero97tsi]

I searched around the forums a bit, found alot of info on it, however nothing pertaining to my particular situation, so I thought I'd make sure that this is what I'm dealing with.

I finally got my timing right, exhaust clog removed, good to go. So I take it out and now when I get on it it goes to about 15 where I had it set, then down to ~12-13, then back up to 15, and I didn't wait long enough to see if it would continue the process, I would have been going much to fast on a public road.

Is this symptom also related to boost creep? The cases that I read about were usually just get to set boost, then it goes up, where as mine is fluctuating.

 

[fwdmaster]

You stated that you have set your car at 15psi,If your car is boosting pass 15psi, that means your car is creeping,if it stays at 15psi your fine

 

[kenamond]

Could the first 15psi just be a boost spike? What rpm does it first hit 15, then what rpm does it drop to 12, then what rpm does it hit 15 for the second time?

Did you readjust your MBC after you removed your "exhaust clog"? If you decrease backpressure in the exhaust, you usually have to reset your MBC.

If you think it's boost creep, do the normal boost creep tests. Mr Peepers' tech article for the WGA mod describes some of the tests.

 

[zero97tsi]

Thanks Kenamond, I didnt notice what RPM it was occuring at, like I said, I let it do it once and I basically no boosted the rest of the way home, just in case. Im leaving again now, Ill see what I can come up with.

I did not re-adjust the MBC, but like I said it didn't pass 15 PSI, which is what I had it set at originally, before the exhaust clog.

 

[kiddsm95]

Only time I noticed boost creep on the T-25 was when I upgraded to a 3" dp, so full 3" from turbo to tip. You should probably check into a decent manual boost controller and set your boost back to 12-15 psi just to be safe.

 

[1992awdlaser]

A t-25 should not have any creep issues. This is due to the turbine wheel being so restrictive even with a 3" turboback that the exhaust gas still goes out the wastegate.

 

[dsmzoom]

So after porting my o2 housing today as well as the wastegate, I'm still getting boost creep..anyone have any suggestions besides dealing with it?

 

[Mr Peepers]

What is your desired boost pressure and what is it creeping to?

What is your exhaust setup?

How did you go about porting your wastegate? Did you follow a certain technique on porting for creep?

 

[dsmzoom]

I would like to run the lowest psi as of now because I have the stock fuel system. I have it hooked up from the wg to the jpipe and it holds at 10psi until 5k then shoots an upwards of 20+ but I always let off. Im running a full 3inch turboback, but the my dp is 2.5 until the flex pipe. I ported the wg hole to allow it to open the full 90* and matched the gasket aswell. Later on I found it, theres no way to make it open the full 90* unless I do your mod.