need some input about a tuning situation

[08SPEED3Veteran]

I know this isnt the tuning issue forum, but this tuning issue i have deals with forced induction. So i went to IAG tuning with another member yesterday and planned on having a pro tune done by Jorge from cobb. First of let me just say that Jorge one of the smartest and coolest people i have ever had the pleasure of meeting. Unfortunately Jorge was only able to give me a mild tune due to a boost creep issue as well as a fuel pressure issue. The fuel pressure issue is an easy fix with some PTP internals, but I need some input about the boost creep. Jorge explained to me exactly how boost creep works and how the factory wastegate, since I have a catless exhaust, can not work as efficiently as my car needs. Boost creep is NOT ABLE to be tuned out. It is a mechanical fault. He told me exactly this, "without better fuel pressure and better wastegate efficiency your car is too badass for its own good" lol. SO...I need to know my options. First off im no expert when it comes to forced induction components like wastegates and actuators and all that high speed stuff hence this thread requesting knowledge. I do not want to attempt to bore a larger diameter hole for the factory wastegate. that to me is bad juju. PG makes the exhaust manifold with the external wastegate and i was wondering if that could solve the problem. OR...is it possible to change wastegates on these factory turbos? And for those of you thinking im looking to run outrageous pounds of boost on the stock turbo, im not. I know the limits and so does jorge. another member on m247 was there for his tune and put down 291 HP at 17 pounds and i was informed that with the fuel pressure fix and wastegate fixed I wouldnt be even have to worry about spiking any more than 20 pounds and making more HP safely due to having more mods. Any input on my situation would be awesome. sorry for the extensive post too lol.

 

[Saskatchewan17]

Get a larger turbo.
You're always going to have boost creep issues with the stock K04 and a catless.
You could invest in a reworked K04. I know PG does them. The service costs around $500 I believe if you send in your own turbo for a credit.

 

[08SPEED3Veteran]

I thought that too but the tuner told me that it was merely a wastegate issue. He explained how the turbo and wastegate work with each other and how the diameter of the wastegate is not large enough to release enough pressure in turn causing the turbo to retain said pressure thus increasing boost. He told me that increasing the size of the wastegate and its diameter even by a small amount will be able to release that excess pressure and eliminate creep completely (something about the geometry of increasing the circumference causing upwards of a 100% increase in efficiency.). I am by no means trying to say your wrong or disregard your input, in fact, im glad someone posted, i just want to be sure i know how to fix this issue safely and correctly.

 

[oaklandopen]

how but welding the stock one shut and getting an external wastegate?

 

[MSMS3]

Get a larger turbo.
You're always going to have boost creep issues with the stock K04 and a catless.
You could invest in a reworked K04. I know PG does them. The service costs around $500 I believe if you send in your own turbo for a credit.

I respect this view. It makes sense and is probably dead on for many owners. However, I have absolutely no boost creep at my state of mods with a catless dp/rp into the stock CBE and a CAI intake. Boost spikes (very quick and transitory) to 21-22 sometimes, but no boost creep. Settles to steady 17 psi. In cold weather I get 18 psi and get slapped with load cut on stock tune, but no creep. When it settles after that quick spike, it holds solid up to 5,500-5,800 after which throttle starts to close and fun slows down.

But I think I'm right at the edge. Any extra power mod would probably push me into creep. A tune to address load cut might well lead to creep. Dunno.

I'd be inclined to stay with the stock K04 or a PG reworked one and have the wastegate port enlarged a little bit. I think that would be greater value for the dollar for me and still have the benefits of the rapid spool up of the small turbo.

 

[08SPEED3Veteran]

I respect this view. It makes sense and is probably dead on for many owners. However, I have absolutely no boost creep at my state of mods with a catless dp/rp into the stock CBE and a CAI intake. Boost spikes (very quick and transitory) to 21-22 sometimes, but no boost creep. Settles to steady 17 psi. In cold weather I get 18 psi and get slapped with load cut on stock tune, but no creep. When it settles after that quick spike, it holds solid up to 5,500-5,800 after which throttle starts to close and fun slows down.

But I think I'm right at the edge. Any extra power mod would probably push me into creep. A tune to address load cut might well lead to creep. Dunno.

I'd be inclined to stay with the stock K04 or a PG reworked one and have the wastegate port enlarged a little bit. I think that would be greater value for the dollar for me and still have the benefits of the rapid spool up of the small turbo.

like jorge from cobb said...boost creep is purely mechanical, nothing that can be tuned out. And its not the turbo that has the issue, its the wastegate efficiency. so in reality getting the wastegate efficiency improved will help not only eliminate creep, but allow the tuner to set the boost at the safest level while still improving performance. so in essence im getting an aftermarket wastegate to lower boost lol. porting is an option, but im leaning towards the pg manifold with the built in external wastegate. more money of course, but id rather not rip apart my car and run the risk of porting to large of a hole. a nice external 38mm tial would be perfect and I can make adjustments without pulling the apart my engine.

 

[Biggs]

haha well you have a month to mull over it. after seeing what he did with my tune, you should be pretty excited about your tuning potential when you get this issue fixed.

I would personally just go with the wastegate alone, but thats just me.

 

[MSMS3]

I understand and appreciate what you are saying. And your solution is a good one but an expensive one. The problem is purely mechanical, as Cobb's tuner points out and the solution is mechanical. But there are easy and less easy ways to get this done. Aren't you looking at over a thousand dollars in parts for the mani and wastegate, gaskets, etc.?

You do know you have to remove and replace the turbo either way? Whether you simply enlarge the port on the stock K04 or go with an external wastegate and new exhaust manifold, you still have to remove the turbo from the engine. There's even more involved in removing both the turbo and exhaust manifold. Are you doing this work yourself? Have you costed out the labor? And they have to shut the port on your stock wastegate some way. Typically they weld the flapper shut with installation of the external one. Don't know what your guys have in mind there.

And then you will get retuned?

Just trying to help you think through all of this and hope your eyes are wide open on the charges and costs involved. Seems like overkill solution for the problem, when you might have a local automotive machine shop help you with something like this that guys with other platforms (Mazda RX7 Turbos) do:

http://www.aaroncake.net/rx-7/s4wastegate.htm

 

[08SPEED3Veteran]

I understand and appreciate what you are saying. And your solution is a good one but an expensive one. The problem is purely mechanical, as Cobb's tuner points out and the solution is mechanical. But there are easy and less easy ways to get this done. Aren't you looking at over a thousand dollars in parts for the mani and wastegate, gaskets, etc.?

You do know you have to remove and replace the turbo either way? Whether you simply enlarge the port on the stock K04 or go with an external wastegate and new exhaust manifold, you still have to remove the turbo from the engine. There's even more involved in removing both the turbo and exhaust manifold. Are you doing this work yourself? Have you costed out the labor? And they have to shut the port on your stock wastegate some way. Typically they weld the flapper shut with installation of the external one. Don't know what your guys have in mind there.

And then you will get retuned?

Just trying to help you think through all of this and hope your eyes are wide open on the charges and costs involved. Seems like overkill solution for the problem, when you might have a local automotive machine shop help you with something like this that guys with other platforms (Mazda RX7 Turbos) do:

http://www.aaroncake.net/rx-7/s4wastegate.htm

wow...that write up about porting is an eye opener. i have the tools and the company of experienced mechanics to help me with the task. I might have to dedicate a weekend to this task when the weather gets nice! thanks for the solid advice!!!

 

[Darth Vader]

Boost creep can be affected by many things that are not just mechanical size of the WG. Try ditching the factory restricted electronic boost controller for a straight mechanical one. I finally tamed the creep by buying the Turbosmart T and ungating it.

I have a CAI/TIP, CS DP and RP and a Forge on the red spring. On the Turbosmart, hooked to manifold pressure, not the compressor fitting, I get NO spiking, the factory boost restriction in lower gears seems ditched (making the car alot more rorty, even at less than WOT) and the boost creep I've fought for months is gone. The car Dashhawks at between 17 and 18 pounds, which is what I want. I can't turn it down, unfortunately, as the MBC is wide open already but, this level is fine with me.

 

[MSMS3]

Excellent suggestion, Darth. I never thought of it quite that way as a solution for creep. Since I do not want to go over 18 psi holding under load, this sounds like a good choice, perhaps better than porting, unless someone is going to be taking the turbo off for some other reason anyway. Old school wastegate porting seemed like something that would solve the problem without screwing with the electronics.

I've just been hesitant to go MBC for fear that some of the safety features of electronic control might be needed to keep me out of trouble! How much of the ECU safety net would remain in place, do you think? Yeah, I'm a bit conservative about protecting the engine from my own stupidity or excessive enthusiasm.

 

[Darth Vader]

The electronic boost control CONTRIBUTES to creep rather than contains it, when you free up the exhaust side.

Properly configured (a definite challenge on this car) an MBC sets a rock solid upper limit and controls the spiking, too.

The rev limiter is still in place, boost cut is still there, since it's controlled of reading manifold pressure and shutting the throttle, load and fuel cuts are still present so, really, it's pretty safe, maybe safer than using the stock EBC on a flow mod car.

That said, it has take me a couple months to get the boost control working the way I want it to. The car poses challenges that other turbo cars do not, in this regard, due to how it's made.

You can not T a boost controller in using the typical method of plugging it into the boost nipple on the compressor and the other end into the wastegate. The nipple has a restrictor in it because the EBC is assisted and so, does not need full signal. You need to T the MBC into manifold vacuum, which is smarter anyway, as that's what the engine sees. However, where to T it in how much hose to use, etc. can affect results. I built a little 4 port manifold out of fittings I had lying around and T'd all my vac/pressure stuff off the BPV hose. That worked but, the MBC still needed to be ungated to finally control the creep and spiking.

I used a Turbosmart Boost T and I highly recommend it as the only MBC for this car.

 

[08SPEED3Veteran]

so many good suggestions! I managed to score a set of ptp internals only used for two weeks for $150 so the fuel pressure issue will be fixed. I think what I really want to do is once this semester of college lets out Ill get under the car with step father aka my mechanic lol and pull out the DP, RP, and the turbo components. I like the idea of boring out the wastegate probably to between 38mm and 40mm. no sensors or electronics to mess up would suit me better as I am more mechanically inclined. That should fix creep completely and then i can go get my tune tweaked to safe maximum performance. thanks for all the constructive advice everyone and feel free to add more!

 

[Darth Vader]

a). Opening up the wastegate in the housing is a waste of time unless you get a better flowing downpipe/exhaust.

b). How are you going to change the wastegate flapper to fit the newly enlarged hole?

c). if you're going to all this trouble, just go external WG and be done with it.

d). You are wasting your time diddling the wastegate on this turbo anyway since it can't support much more flow on the intake side. You do the wastegate, push up the boost (as that the only reason to do it) and you cross the surge line and just heat the intake charge and/or melt the dinky turbine shaft this thing has.

 

[MSMS3]

Darth, maybe I'm missing something. I value your judgment on these matters, as I'm more into the mechanical side of things.

OP does have a Corksport DP/RP now. I don't know much about its design or flow characteristics compared to my catless Turbo XS. Are you saying it does not flow well enough to justify a bit of porting on the wastegate? If that is the case, then he is wasting his time. But he does apparantly get some boost creep.

I thought OP was just trying to tame the creep so as to allow allow modest 17-18 psi AP tune without any other mods, but maybe I'm not appreciating OP's ultimate plans.

I agree that if OP is trying to push the turbo past 5,800 rpm on a regular basis with a 17-18 psi tune he is going to destroy the turbo for sure, regardless of his state of tune, and regardless of whether he ports the wastegate.

The porting I was suggesting does involve welding a thick washer of port matching diameter to the bottom of the stock flapper.

I have not done this myself. I admit that. It would be an easy project for me, even without our machine shop equipment once the turbo is off, and something most guys with a few basic tools could do.

I'm just basing my views on what I know to have worked on RX7's and the "how to" I found on the subject. I'm inclined to move in that direction if I get any more mods and get real boost creep. I'm just a MBC "scaredy cat" pussy when it comes to trusting myself to properly set the MBC.

 

[Darth Vader]

Darth, maybe I'm missing something. I value your judgment on these matters, as I'm more into the mechanical side of things.

OP does have a Corksport DP/RP now. I don't know much about its design or flow characteristics compared to my catless Turbo XS. Are you saying it does not flow well enough to justify a bit of porting on the wastegate? If that is the case, then he is wasting his time. But he does apparantly get some boost creep.

***If he's got DP/RP, my comment is unjustified, in that regard***


I thought OP was just trying to tame the creep so as to allow allow modest 17-18 psi AP tune without any other mods, but maybe I'm not appreciating OP's ultimate plans.

***You can do 17-18 without porting the wastegate, that's alot of work for little reward, at this level of performance, on this turbo.***

I agree that if OP is trying to push the turbo past 5,800 rpm on a regular basis with a 17-18 psi tune he is going to destroy the turbo for sure, regardless of his state of tune, and regardless of whether he ports the wastegate.

***I believe 17-18 is reasonably safe, given the use of premium fuel, good oil, regularly changed and proper cooldown after hard running. That's the max though you'd wanna push this thing, given the compressor map it has.***

The porting I was suggesting does involve welding a thick washer of port matching diameter to the bottom of the stock flapper.

***It's pretty tight in there, given the confines of the engine bay and the tight turn past 90 the DP has to make right off the snail. Not saying it's impossible but, it's pretty snuggly, especially with CS divided flow tubes. Also, the stock flapper is a pretty flimsy piece and I wouldn't want to hit it with welding heat and extra weight, if it was me. As before, there's the question of why, when the desired results above can be achieved without the work.***

I have not done this myself. I admit that. It would be an easy project for me, even without our machine shop equipment once the turbo is off, and something most guys with a few basic tools could do.

I'm just basing my views on what I know to have worked on RX7's and the "how to" I found on the subject. I'm inclined to move in that direction if I get any more mods and get real boost creep. I'm just a MBC "scaredy cat" pussy when it comes to trusting myself to properly set the MBC.

***It would also be valuable to see how much of the time is spent at 0 WG duty cycle. If the WG is full open all the time at high load/WOT, some porting may be of benefit but, if it isn't really banging 0 alot, it won't help.***

 

[08SPEED3Veteran]

maybe i should just ditch the catless turbo back exhaust and get a nice catback. cuz personally i dont know how to do it or what would go into putting an external wastegate in. All i want is to eliminate the boost creep, get a tune that improves drive-ability and horsepower safely, and focus on suspension and external mods. I dont want a hotrod.

 

[Darth Vader]

External WG is just a pipe off the DP, going into a WG assembly so, you'ld have to drill a hole, weld a pipe and flange and, hook up some vac lines. These things are mega-noisy man and it's lame to have an external WG for a TT drag car slapped on a stock turbo car.

Going back to your problem. Absolutely money you can tune this into a reasonable level of control at 17-18 pounds using a combination of AP and a manual boost controller. Lots of us are doing it without an AP/Standback.

True boost creep IS a mechanical problem but, you can work around it using electronics and mechanics. Don't give up on it.

Cheapest/easiest out? Slap a cat into the RP and call it a day.

 

[MSMS3]

Cheapest/easiest out? Slap a cat into the RP and call it a day.

Yep. Maybe just having that reso in the race pipe is helping me out there. I doubt it produces much resistance to flow, but maybe there's a little and that's why I'm not getting creep.

Your advice for OP to monitor wastegate duty cycle makes a LOT of sense to see if he's truly maxed out. And yeah, OP needs to try to find someone whose tried to port this turbo. My suggestions are theoretical based on a different turbo on a different Mazda and based on my experience on Saabs and Volvos. I don't know if there is enough clearance on flapper swing or enough "meat" on our flapper to weld on to it. The RX7 turbo wastegate flapper is small too, but it worked there.

It would be great if there is anyone on this forum who's ported the wastegate to step up with their thoughts.

Otherwise, a cat or maybe just a reso in the rp might get OP where he needs to be. Maybe AP's recommendations to use catted dp's might be based on something more than just trying to please the environmental police.

 

[Darth Vader]

Otherwise, a cat or maybe just a reso in the rp might get OP where he needs to be. Maybe AP's recommendations to use catted dp's might be based on something more than just trying to please the environmental police.

No doubt that's Cobb's thought given how much of a pinner this turbo is. Enviros are certainly no concern as no tuning device is going to pass smog anywhere, as long as the end user can make adjustments to it.

You can't have V8 grunt in a 4 banger and not give up something somewhere else.