that makes perfect sense, but what if i swap the intercooler and intake setup back to the previous setup (which i actually did) and it does the same thing, and the intake temps are the same as they were previously?

i am not familiar with supersonic wastegate choke. can you explain? and how did you determine that the limit of said wastegate choke is ~12psi on this turbo?
and again, see my previous comment about changing the intake/IC back to the previous setup.

those are both possibilities, but i don't want to do either of them. i want to figure out why this setup controlled boost for 6 months and suddenly stopped!

also, what is MatchBot?

i sold my perfectly good precision 6262 / dual wastegate (recirc'd setup) complex setup to build this nice simple EFR IWG setup that may NOW require running at 15psi. :/

the recirculation of dual wastegates is overly complex, and i will take a bullet to the brain before i deal with dual vented wastegates rotary chainsaw noise again.




so think about all that, and watch this video (notice the boost gauge on the laptop). and don't comment on my broken tach.
it holds 11psi at ~100*F (the same air temp i had tonight after heat soaking a little and testing the boost creep)




so one thing i have left to do is switch back to gasoline from E85, but this was happening before i started running E85 (this is actually the reason i switched to E85... in case i couldn't get the boost to go back down). though i cant imagine how that would change it, being that i wired the wastegate flapper completely open and it crept up the same amount.

 

Yeah the other thing I was going to say is if the weather is cooling down it can cause over boost issues if you were already at 100% open wastegate. Cold air intake can do the same thing.

 

also i replaced the spark plugs tonight and went out to do more testing. i put the actuator back on tonight (after last night's wire-open-wastegate testing) and went out for a test.

i can brake boost in 3rd gear on the interstate and just watch the boost climb up to 15psi. the gate clearly opens at 7psi, then at about 5500rpm the boost just climbs and it starts misfiring around 14psi, but it will smoothly boost from 7psi to about 13psi with no misfires, seemingly to simply overrun the wastegate.
i can't seem to fix the misfire at 15psi on the e85. i'm not sure why, but even with new spark plugs it won't fire smoothly at that boost.

 

Maybe the gap on the plugs is too large? What does your ignition setup look like? I can't remember if you had mentioned what you were running in a previous post.

 

Is it possible you had a boost leak before you switched ICs and now don't.

I would put a small restriction in the exhaust as far back as possible to limit the boost and forget about it.

I chased boost creep for about 10 years on my previous set-up because I couldn't stand the thought of not running my 3.5" exhaust unrestricted, but honestly the "cure" hurt overall power more than the "bandaid" did.

the recirculation of dual wastegates is overly complex, and i will take a bullet to the brain before i deal with dual vented wastegates rotary chainsaw noise again.

What? I used to think that noise was bad, but now I think I got used to it. What?

 

^^ This thought crossed my mind when I was thinking about your issue. Your testing has shown that it is not the parts. The only other thing that changed is the installation. Did you pressure test the system prior to tuning at 11psi?

Im also wondering if you've had any change in EGT.

I know this isn't the answer you're looking for, but we always used to port out the waste gate hole on internal gate turbos to the maximum diameter that can still seal with the flapper. I did it on my AX53B70 Apex turbo on my S13 and it did help. For the newer generation of turbos like the EFR, Id assume BW did quite a bit of R&D before determining a WG diameter though.

What are your plugs gapped at?

 

I think something in the tune has changed, and egts are up causing the boost creep. Like a failing coil. He has misfires that he cannot fix via tuning. I have seen plenty of setups boost creep from similar, like base timing off or not enough timing...

 

^ Yea, and since Cartmill does not want to pony up the $$ for pre-turbo EGT sensors we won't know.

 

Arca, i am using regular rotary-type NGK spark plugs (BUR9EQ) that have the flat face and can't be gapped.
the ignition setup is 4 LS1 coils firing sequentially with 5.5ms charge time (pictured earlier in the thread)

this is really the only option. i already had a lame attempt at restricting the *intake* side by putting my smaller filter on my CAI and putting 2 (two) socks -really- over the filter to restrict flow. didn't do anything. my corvette track event is in 4 weeks, and it's starting to look like the only option is to restrict the exhaust.

i have rotary type spark plugs. the gap is like .043, but it has 4 electrode grounds, so i'm not sure how that compares to a single-ground "conventional" type spark plug.

1. i have used this same haltech fuel/ignition map for 3 full track events. i've only recently switched to e85. i am going to switch back to gasoline just for ***** n giggles to rule out everything (even though this issue STARTED on gasoline --hence the reason for switching to e85).
2. the misfiring doesn't occur until the boost is way past where it's supposed to be.
3. failing coil or not, it doesn't misfire from 0-13psi, after the boost is already creeping up.

and as far as something in the AIRFLOW changing, i used the exact same fuel/ign map, swapped back to my previous intercooler, and previous small air filter, and the issue remained.

 

I have a 2.25" exhaust restrictor if you want it. i'll send it out...just pm me

 

just run 15lbs and stop being a pansy

 

You are probably experience complete spark blow out above 12psi( where you never were before). Which shouldn't be happening..
Its hard to feel small misfires while street driving( which you probably are getting below 12psi)

You are the only guy EVER to warp one of my manifolds. Even Shawn has not warped his shorty( which doesn't have the center cut-out, and I did over 7 years worth of manifolds without the cut-out). Shawn was also running over 2x your boost pressure.

It all points to a mechanical ignition related issue!

Sort out the ignition blowout at high boost first, and I bet it will solve the rest of the problems...

 

The plugs are your misfire problem. I can't believe you weren't misfiring at 10 PSI

You absolutely need 10 minimum I'd go 10.5

My guess is the creep is no different than with twins you need a bigger wastegate if you want to run low boost levels. The colder or thicker the air the more it creeps. I don't see anyway ignition problems could cause creep if anything it should cause decreep LOL. On the flip side if your exhaust temps are out of control which I can't imagine while running e85 you obviously need to sort that out asap so you don't loose your engine.

Regarding the divided center section on the manifold that's a must do for anyone really tracking this car and using gas. It's probably not a problem with e85. When I say really tracking though I mean running TT3 back marker lap times minimum. If you aren't doing that you are not even beginning to drive the damn car. A T1 corvette should be a road block if your car is making 350 HP much less a modded street c5.

 

1. fritz, i'm curious as to how would running a colder plug would help the misfire. i'm not an ignition expert, but it seems like that would have the opposite effect in this situation.

2. i swapped the intercooler/intake setups back to the old setup to make the air temp the same, and the problem persisted. and i'm pretty sure the EGTs are not out of control, but of course i can't verify that because i don't have EGT sensors.

3. i'm not sure what you were responding to with the divided center section part. i don't think the divided turbine housing is being doubted.

 

i am going to do some more troubleshooting tonight and i'll report back.

there's no way my engine magically started pumping out more exhaust with all the same parts installed on it...

 

I can't run 9s on any track car I've ever had with a single turbo attached to it and I usually run between 10 and 12 psi. Temps go up and after two laps I'll get break up.

This is why there are colder RACE plugs for this/your application.

What I meant is once the go pedal is used for extended periods you will warp manifolds PERIOD when running on gas so the center section must be machined to avoid a quick exhaust leak. Eventually you will crack the manifold, the dp will break off etc... LOL

If you weren't getting boost creep and everything is the same clearly it's not creep but that's my 1st guess.

Possibly as someone else mentioned prior to this you had an exhaust leak

Otherwise I have no experience with boost creep being anything other than a wastegate issue and can't help

 

fritz that is good to know. which actual spark plugs are you using? i will run the colder plug just to be safe (though i havent blown an engine in almost 10 years using bur9eq in all 4s).

 

I run these cheap bastards but you will need to machine your plug socket (make the leading edge thinner) to fit into the tight plug hole on the housing.

NGK Racing Spark Plug (B10EGV) 5927: Choose the best Motorcycle Spark Plug at Advance Auto Parts

If you plan on running more than 14 or 15 PSI I'd go with 10.5s

 

thanks fritz,


on a lighter note, i got my aluminum prints in from printerpix.com.

i'm actually not happy with the quality, as they framed it incorrectly and cut off part of my picture (in the one not pictured below), but this print ended up good:

 

Lots of people run BR10EG. Which is an even cheaper bastard. I believe there's quite a few people running them in high boost, 500+whp applications here on the forum. You can close the gap if you experience break up. Maybe for your boost levels Fritz's plug is a better fit. I've heard the BR10EG are not the best as far as idle and low end. They're cheap enough to give them a try and not feel bad if they don't work out.

Then there is the NGK R7420 which is available in many heat ranges. I'm pretty sure everyone will agree this is the "best" plug if money is no concern.

 

just an update:

i put a silencer in the catback and the boost held 7psi til redline.

 

You have a wastegate problem

 

fritz you mean a "wastegate too small for ported engine low boost" problem


turbo kit is for sale in the classifieds section.

 

Yep, you need a larger wastegate if you want to run low boost

 

so you're selling your whole setup because you can't run that low of a boost?

it seems kind of odd.

what setup will you be going with now?

why don't you just run higher boost? or does that negate the philosophy of the type of build your going for?