Boost creeping with Tial 38mm

[Ondonti]

Went for a scary ride. 2 4th gear pulls.

#1 pull it was way to lean and boost was creeping badly. 3000 rpms and we were at full boost 5 psi. boost then crept up to 9+ psi near redline and the car leaned out to 15:1 a/f. EGT's got up to 1725. Not good. Glad I had a datalog of that. Cranked up the rising rate regulator.

#2 pull 3000rpms = 5psi. Creeps to 6ish psi and then above 4800 rpms it creeps up to 8-9psi. My guess is the engine really is moving air at those rpms and the tial 38mm is not able to handle it. Only leaned out to 13:1 but that was a blip it was more like 12.7:1. Added a little bit more fuel.

This is with the custom intake manifold fixed and cams advanced 4 degrees.

So my question is this. When if turn the boost up, is it going to creep even higher or will it probably creep to the same numbers as before?
I dont want to turn it up to 8-9 psi and then have it creep to 13-14 cause I dont have enough fuel for that.

Wondering this question because if its going to be a POS and creep that high, then I might as well run the same boost number throughout the RPM range so tuning the a/f is a bit less weird.

Is my camshaft timing complicating boost creep or shouldnt that be a non issue above 4800 rpms where the creep gets really bad?

One thing I am going to try is giving a dedicated vacuum line to the wastegate as its currently sharing with a lot of other stuff.

[Turbo224]

I would definatly dedicate a single vacuum line to the wastegate. Are you running a manual boost controler? The shorter the line the better, but I am sure you already know that.

[Ondonti]

No boost controller on the car right now. I have a grainger that works great though.
The line is fairly long too. Like 4 feet. I really dont know anything about how to have a good wastegate line or what makes one bad etc.
I was planning on going out to race with cory etc on 5psi but the car is scary when it starts creeping cause it feels like its accelerating faster @ 100mph then it does at 70mph (in a 4th gear pull).

[turbovanman²]

What spring do you have installed? Are you using the lower nipple and if so, try hooking it to the compressor side, its a bit more accurate and stable sometimes than vacuum.

I am so glad I went with an external, when they work right, its awesome, the boost just stays rock steady,

[Ondonti]

i have it on the lower nipple (upper is totally empty and open)
Its hooked to the intake. Good idea though. Simply putting it on the compressor housing means less boost because its referencing before the intercooler. Plus my compressor housing is like 1 foot from my wastegate

I dont really have a nipple that fits the compressor housing though...I have a plug in it but I think its only lightly threaded cause it doesnt really fit.

[turbovanman²]

i have it on the lower nipple (upper is totally empty and open)
Its hooked to the intake. Good idea though. Simply putting it on the compressor housing means less boost because its referencing before the intercooler. Plus my compressor housing is like 1 foot from my wastegate

I dont really have a nipple that fits the compressor housing though...I have a plug in it but I think its only lightly threaded cause it doesnt really fit.

Dumb question, but do you have the spring installed, if it uses one?

[Ondonti]

the spring came installed.
The wastegate used to work great on a less efficient turbo/engine setup.

I dont even know what the top port on the Tial does and I think the fittings are in the attic if I have them.

Going to try to reference to the compressor housing but I think my vacuum barb in the turbo will be pretty ghetto since id have to buy a properly fitting one online. I probably have to use this 1/8" pipe nipple that I will only be able to lightly thread.

[turbovanman²]

the spring came installed.
The wastegate used to work great on a less efficient turbo/engine setup.

I dont even know what the top port on the Tial does and I think the fittings are in the attic if I have them.

Going to try to reference to the compressor housing but I think my vacuum barb in the turbo will be pretty ghetto since id have to buy a properly fitting one online. Im hoping the t1 garret I have upstairs has one :P so I dont have to use this 1/8" pipe nipple that I will only be able to lightly thread.

The top one is used when you add an MBC or electronic controller.

Maybe it is too small??

Is the WG new? maybe from sitting the diagphram got ripped. My used one did the same thing and it had a hole in it.

[Ondonti]

The top one is used when you add an MBC or electronic controller.

Maybe it is too small??

Is the WG new? maybe from sitting the diagphram got ripped. My used one did the same thing and it had a hole in it.

Dont quite understand.

I was able to use a MBC (grainger) about 2 years ago with no problems. i just put it in line with my reference to the sideport. Controlled leak and the wastegate then opens later. How do you setup up this top reference port stuff????? most cars I have seen are all setup only using the sideport.


The wastegate was purchased in spring 2005 so I guess it is technically about 2.5 years old. It has only gotten limited use in the last 2 years though after i started my new project. I alraedy had the diaphram in my RRR burst this spring :P

[Frank]

+1 on springs, vacuum line length, and which barb to use. Those will make things consistent. Also you might find that the lower boost levels being consistent with the stock spring are going to be harder to maintain then higher boost levels.

Also make sure your BOV isn't bleeding off boost.

On a side note, if you are going to gauge any tuning off of your EGT, make sure your cams are at 0*. Cam timing can play effect on your EGT and fool you into thinking something else is wrong. I recommend that you tune at 0*, make it look good, then go to where you want it to be.

[turbovanman²]

Dont quite understand.

I was able to use a MBC (grainger) about 2 years ago with no problems. i just put it in line with my reference to the sideport. Controlled leak and the wastegate then opens later. How do you setup up this top reference port stuff????? most cars I have seen are all setup only using the sideport.


The wastegate was purchased in spring 2005 so I guess it is technically about 2.5 years old. It has only gotten limited use in the last 2 years though after i started my new project. I alraedy had the diaphram in my RRR burst this spring :P

I'll dig up what I used on the van when I get home, it works, the boost is rock solid, I set it at 15 psi, its 15 psi,

[Ondonti]

+1 on springs, vacuum line length, and which barb to use. Those will make things consistent. Also you might find that the lower boost levels being consistent with the stock spring are going to be harder to maintain then higher boost levels.I assumed that lower boost levels are harder to control but I sorta wanted to know if I cranked up boost to initialy be 9-10 psi would it creep even higher? If I have enough fuel to handle 10psi @ 6000 rpms I might as well turn boost up a little in the lower rpms. One short term fix I might try if things seem to have problems is swap in an automatic computer because the extra 400 rpms of rev limiter you get on the 5 speed ECU get REALLY lean because the stock volumetic efficiency is supposed to be horrible there. A/F jumps about a point in the last 500 rpms. Still waiting on bansheenut to solder something on MS. Might hook up the methanol kit and set it up to enrichen things during those episodes when boost is creeping. I think i will just have e85 in the methanol tank when that happens. My minimum nozzle size is 2 m5's and 1 m3 though because I bought it to be a 3 nozzle setup with the much bigger 100 watt 1.8G/min pump.

I will concentrate on simplifying the boost reference line first.

Is there are cheater way of seeing if the diaphragm is damaged? I guess I can just hook compressed air up to it and then look for air coming out the top port or what?

Also make sure your BOV isn't bleeding off boost. Going to be pretty hard to prove that one Its a 1st gen DSM so 5-10psi should be okay I thought. Is there an easy way to do this? I have an air compressor but I dont really know how to simulate the engine running under boost this as blocking off the 4" turbo inlet and having it hold 10psi sounds pretty danged impossible. Maybe if I had a big piece of flat strong rubber that I could worm gear clamp over the inlet....but I dont.

On a side note, if you are going to gauge any tuning off of your EGT, make sure your cams are at 0*. Cam timing can play effect on your EGT and fool you into thinking something else is wrong. I recommend that you tune at 0*, make it look good, then go to where you want it to be.
Not really tuning, just trying to not blow things up. I only mentioned the EGT's to show that they were high (thanks to the horrible a/f ratio)When I have the MS on there I will definitly do this as I will probably be sharing my files with other people anyways.

bolded comments I guess.

[turbovanman²]

A simple way to see if the BOV is leaking is make a blockoff plate out of cardboard and place between the flange and valve.

As for the WG, check out this diagram, scroll to page 10.

http://www.greddy.com/img/PHP/products/pdf/689.pdf

[Ondonti]

How do I get pressure between the cardboard and the valve to force it to leak?I dont quite understand there.

BTW I think you are taking the verbal instructions of that PDF too literally. The picture shows the side port being used but the side port on that brand of external is "on top" also.

[turbovanman²]

How do I get pressure between the cardboard and the valve to force it to leak?I dont quite understand there.

You block the BOV so it doesn't work, thus eliminating the valve. If your problem is fixed, then the BOV needs to be modded or you have a bad one. If the problem remains, the BOV is good,

BTW I think you are taking the verbal instructions of that PDF too literally. The picture shows the side port being used but the side port on that brand of external is "on top" also.

Are you saying yours doesn't have 2 nipples? All the ones I have seen do, and when using a boost controller, both of them are used, as in page 10.

[Ondonti]

that page 10 doesnt have things hooked up to both nipples. Just 1 line leading from the wastegate to the boost controller, then a line from the boost controller to the vacuum source. The external wastegate section was sadly not well detailed like the internal gate sections of that PDF so its not as helpful as it could be

I think I have the other nipple in the tial box in the attic Im not sure. Its not installed non the less.

[turbovanman²]

that page 10 doesnt have things hooked up to both nipples. Just 1 line leading from the wastegate to the boost controller, then a line from the boost controller to the vacuum source. The external wastegate section was sadly not well detailed like the internal gate sections of that PDF so its not as helpful as it could be

I think I have the other nipple in the tial box in the attic Im not sure. Its not installed non the less.

Yes, both nipples are used, I fell into the same trap. Read the instruction's and you hook both lines to each or a boost source, IE compressor.

[Dave]

Where is your WG port located? If it's not in a collection of exhaust pulses that could promote higher boost levels as RPMs increase.

[8valves]

With no offense intended, you're not past the capabilities of a single 38mm wastegate right now.

Having said that, the problem should be less once you turn the boost up, since it will have to bleed less gas in total.

[Ondonti]

With no offense intended, you're not past the capabilities of a single 38mm wastegate right now.

Having said that, the problem should be less once you turn the boost up, since it will have to bleed less gas in total.

Talked to a guy with a gt35r evo on e85 and he said he had the same problem until boost was set at 22ish then it levels out for him.

I know you can run a single 38mm on a 1400whp supra but a lot of other cars require much larger wastegates for smaller engines with less power.

The way those supras are set up they have no need to dump tons of air to maintain a certain boost pressure.

I dont understand what you mean by "not past the capabilities" because that doesnt give any info. Upon searching I dont see any HP requirements to have too small of a wastegate.