Stock turbo and no cat

[sy538]

Will porting the wastegate passage be enough to keep boost under control? It just seems like there is a long way to go. I drove around a little with just the downpipe for an exhaust, (watching the computer the whole time) and I could only go about 60% throttle or so. It will start getting kr at about 12-13 psi. I assume it now makes kr at 12 psi because without the cat 12 psi is more airflow then 15 psi was with the cat. Does that make any sense? O2s were fine.

I really don’t want to put another cat on the truck, or buy a bigger turbo. I’m planning on getting a RPM cat back and porting the wastegate, but I just can’t convince myself that will be enough. It wants to make a lot of boost, fast. I knew that would happen, but it is more then I expected. After pulling the turbo and looking at it, it’s hard to imagine getting the wastegate to flow enough more to keep boost down.

Another thought I had was getting a 10cm exhaust housing, but I don’t know if that will work or not. Is it possible to just change housings like that? Would a stock center section and exhaust wheel go together with a 10cm housing? Is there a TD06 10cm housing or are all the 10cm housings for the TD06H? The TD06H has a bigger wheel, right?

 

[Tooky]

Re: Stock turbo and no cat

Your suspicion is definitely warranted. I ran the crap out of my stock turbo and I always struggled with that shitty Mitsubishi internal boost control.

You got me thinking so I dug thru my photo archive and pulled these pics up from when I was porting my stock turbo in 2003:

Beginning to port (I dont think I touched the wastegate area yet here):

Finished!

Do I feel like the wastegate porting was worth it? Not really. If it made a difference, it wasn't a very big one. Maybe it could have been ported more aggressively than what I did, though.

At first I ran an open downpipe just like you. I found a DM file showing boost control between 17.3-20.0 PSI on a run with the BoostValve.com manual controller. (The Ultimate electronic boost control never worked for me, it was absolutely dreadful)

Later in the year I ran a 2.5 test pipe with ATR 3" catback and ultimately ran 12.26 @ 108.6. Here is a look at that run:

You can download the datamaster file from that run (along with the rest of my runs) on my site if you want.

 

[dgoodhue]

Re: Stock turbo and no cat

Another thought I had was getting a 10cm exhaust housing, but I don’t know if that will work or not. Is it possible to just change housings like that? Would a stock center section and exhaust wheel go together with a 10cm housing? Is there a TD06 10cm housing or are all the 10cm housings for the TD06H? The TD06H has a bigger wheel, right?

I tried the porting the exhuast and like tooky and I didn't notice much of difference. I had a high flow cat and my sy would slightly overboost (creep up past 1psi past my desired setting in 3rd gear) I could in the data log the ECM was trying to keep the wastegate closed. I think the 10cm housing would help. I am not 100% sure if their is a 10cm2 TD06 hopusing, but I suspect their is. I had at one time a 12cm2 housing for TH06 wheel.

 

[It's just a six]

Re: Stock turbo and no cat

If you are going to port the wastegate hole you need to remove the plug & the valve in order to inlarge the wastegate hole.

Well, to be on the safe side & not damage the flapper valve I would remove it.

Also, do not just bore a straight hole & not radius the turns/edges,if you just bore a straight hole you will not get the same ammount of flow as if you had radiused the edges.

 

[sy538]

Re: Stock turbo and no cat

Tooky, damn man, very cool site. Looks like you have a ton of work in it, thanks.

Dave, yeah, your post in the ebay thread is what got me thinking about changing the housing. What did you use it on? How much was it? What is a TH06? Is that the same as a TD06H?

Six, at first I was just thinking about smoothing the edge going to the wg and the area coming out of the wg going to the dp. But I think you are right, the hole itself will need to be bigger.

Just to make sure I understand Mitsubishi’s system
TD06 = the center section and the exhaust wheel
17c = the intake housing
8cm2 = the exhaust housing

Is that correct? What describes the intake wheel?

Thanks for the help.

 

[dgoodhue]

Re: Stock turbo and no cat

Dave, yeah, your post in the ebay thread is what got me thinking about changing the housing. What did you use it on? How much was it? What is a TH06? Is that the same as a TD06H?

TH06 is TD06 typo I never did use it. I bought from a Texas Turbo shop on ebay (same place that was selling the new 17g-TD06-8cm2 turbo's on ebay recently). It was little over $100 but they clearing them out, they were originally selling them for $195. I never used it though. I sold it to 'It's just a six' (posting in this thread) and he had it machined for TD06H and mated it with 20G wheel.

 

[sy538]

Re: Stock turbo and no cat

I got a great deal on a used TD06-10cm2 housing and put it on. My truck is 99% stock, including stock chip and map, basically I just have an IC pump and fuel pump, and now 10cm housing, and downpipe only for an exhaust. The housing got rid of almost all the knock, sometimes get 1-2* in third, but the wastegate is still way too small. If I hold it at 50% tps the wastegate will open all the way while the truck is showing 15 psi on the stock gauge. I have no idea how much boost it is running at 100% tps, but there is almost no knock and the O2mv is good. I’ll have a real boost gauge hooked up in the next couple days.

 

[TYTILIDIE]

Re: Stock turbo and no cat

FWIW, to all you guys and running no cat. I ran no cat on my stock turbo and had a Greddy EBC and it had rock solid control, yes it was a straight line across the board. The boost control issue is not in the cat or the turbo, its in the controller.

 

[sy538]

Re: Stock turbo and no cat

I agree the stock control sucks, but no controller can make the door open more then where the door hits the plug. Even with the actuator rod off the wg lever, it still can’t keep boost down.

How much boost were you running?

 

[syclone3]

Re: Stock turbo and no cat

I deal with so many turbo cars on the dyno weekly. High percentage have some sort of boost controller issue. Manual and electronic. With my beater Syclone, no cat, stock exhaust. Stock solenoid and now a manual controller down to the gate from the sol. It holds fairly solid and gains 1-3 psi on a shift then settles back in. 4th gear will creep and climp depending how long I stay on it. One of the reasons I run 100 oct all the time I try to keep it 17 psi so when it climbs or overshoots on a shift it hits 20 max then drops back.
If you were to look at the turbine housing as people have mentioned. Its a joke how far the stock valve opens. Try 30-40 degrees in some cases. Then the valve hits the steel plug. Porting you need to concentrate on the area on the bottom and really elongate the turbine housing feed area to the gate hole and the lower edge of the seating area. The 14cm 20g is really bad on the creep in most cases and needs an external.

I got an HKS external on a stock crossover pipe I want to put on the beater and may just swap the stock turbine housing with a ported unit that has the flapper removed and hole welded in. The gate setup worked well on my other truck with a 60 trim Turbonetics turbo. Putting headers on that truck now.