Yah post up a side view pic of that turbo, so I can see what the snail looks like....Max

 

The main runners and WG runners are 2 inches in diameter. I believe the OD is 2 inches and I'm not 100% sure what the thickness is of the pipe wall. I will have to measure it.

 

TD07-25G
Compressor
Inducer- 2.365"
Exducer- 3.06"

Turbine
Inducer- 2.9"
Exducer- 2.54"

Have an idea what a p-trim turbine is?

 

here is the turbine housing pic

 

here is a overall pic.

 

Is your housing single entry ? If so a collected header before the turbine entry will control boost OK as you have experienced given your WG position.

A divided manifold with a WG placed as you and setzep have will always strugle, I have been through it, friends of mine have been through it............ ALL running TO4S type turbos with 1.32 rear housings (divided with P trim) with large WG and poor WG positioning. Waste gate positioned in the turbine housing will cure all these problems.

Too low a turbine flow rate results in a choked flow with mid range boost spikes then a taper off in the boost that the unit can deliver, not a steady increase in boost pressure with RPM increase as he suffers from, I went through the exact same problem with an earlier styled manifold running the TO4S combo with HKS 45mm race gate.

His whole problem is that where the WG is positioned it cannot bypass the energy needed to sustain the turbine speed to supply his engines flow rate, its a lot to do with the extra engery offered when you harness the exhaust pulses, and the simple facts are that you cant control boost well when you stick it in that position. THIS ONLY APPLIES FOR LOW BOOST. Boost levels over 15psi can be controled perfectly even with his set up, its just a pain in the **** if you too use realy low boost (<15psi).

Setzep, if your manifold was not divided and not so well made you would not have any issues I still think you should ditch all these ideas and just put the ******* thing back on your car ! 15psi should be your minimum and start focusing on running 20psi and above

 

Peter- he has a 1.15 divided turbine housing.
haha, 15psi minimum... It will spin the tires in 3rd gear on cold pavement at 4500rpm and 10psi, I don't need to run 20 It's a street car and gets 92octane not the 110 I'd have to run for 20+. Maybe I should just put a hks cast undivided on it and call it a day

 

OK, his housing looks a fair bit smaller than yours ?

All I can do is pass on the experience of what I went through, I had exactly the same problem as you, yet some of my other friends had no issues at all. (1.32 P trim users). The ONLY thing I could come up with was WG placement as being the single biggest issue.

Mainly cause I had a restrictive turbine in a hybrid before as Max was eluding too and it was a big boost spike in the mid range, not a constant "creep" linear with revs like you are experiencing.

I tend to look at it this way (very basicaly) if your turbine housing/wheel combo offers little in the way of resistance, then you will have more issues controling boost inthe lower pressure ratios, if on the other hand you run a smaller housing or more restrictive set up you will be able to control boost better at low flow rates.

If he had a 1.32 I would bet he would have the same problems like I had. I could not run less than 13.4psi boost at max torque even with a 3 psi WG spring ! But with a 14.5 psi WG spring, it would control boost perfectly at this level !!! Go figure

 

hrmmm... maybe I should put in the 13psi spring I have. Too bad I can't just go try it now though, living in Minnesota sucks in the winter. Sand+salt+snow doesn't make a real good road for testing on.

 

P Trim:
2.920 Inducer
2.542 Exducer

jeff

 

Jesus, I wonder if I have a p-trim in my Td07??

Know what a 60-1 compressor measures?

Thanks

 

60-1 is
inducer- 2.324"
exducer- 3.000"

All in all about the same turbo. My measurements came off a cheep dial caliper so I may be off in the .0X range

 

I have run from 8 to 19 psi boost, and everywhere in between, my boost is still controlled right to the decimal point , which again leads us back to the turbine..

Mine is 1.15 divided p trim with equal length primary runners...With the tuning and mods to my car, it spools like a stock turbo, but pulls hard to 9 g's....
With the S4 stock turbo scenario I was mentioning that was a slow build then a big jump at the end of the rpm, much like Setzep is having...
I have to say thats one F'ed up looking exhaust housing, that doesn't even look like the mistu turbos I saw in Japan on rx-7's, it does look like one I saw on an EVO however..hmmmm.......Also the wheel of that turbine is really wide, with a tight blade spacing....I would bet you could hand pump the wastegate wide open with that turbo and still spool it to 12 psi ...
CLIP IT!...Max

 

I'm going to have to chew on this all for a while. In the meantime I think I better get a hold of someone at mitsu and find out the reasoning behind my turbine housing looking like that.

 

This is interesting! Do you have a pic of a manifold that was done the "proper" way with the waste gate in the turbine houseing? Im haveing a hard time visualizing this!

 

Yeah, I'd love to see this too. Especially when you talk about remote-mounting the wastegate... I can't help thinking that this would be tricky to plumb have some negative implications for the flow. I'm NOT saying that I doubt the claims, I'm just having a hard time picturing it...

Pics would be a godsend.

Thanks,
Phil.

 

That looks like every other TD07 exhaust housing I have ever seen on a rotary, and I have seen a few.

 

It would be interesting to see which housing they use on a t-78 and t-88, from the mistus line up... The mitsu turbo's I saw had a smooth even turbine housing, that looked much like a normal garrett turbine housing on them...
DO the t-78 say mistubushis still on the front cover, theones I had in my hands, still said mistubishi on the front cover, I am wondering if I had a t-78 or t-88 in my hands, they did not say Greddy on them at all...
Question for IGY, were they running AFM's and Cats, or stand alones with nothing but a filter in the intake tract?
Most of the cars I saw in Japan, were still running alot of the emmisions/stock ecu sensors in place...
The only other thing I can think of setzep is that the material you use is retaining alot of heat, stainless isn't a great heat transfer material, especially 1/4 thick stainless, I used Tube, you used Pipe, my stuff is about half the wall thickness....Max

 

IGY- Do you have any more input on the TD07 turbos with the 17cm turbine housing? I'm trying to think if this style turbine housing is even a good candidate for a divided manifold because of the "dual a/r" style housing. I'd hate to have one rotor see more back pressure than the other. Or isn't it actually a dual a/r housing? Sometimes looks are deceiving. Also do you know if I could find a larger turbine housing for it if I wanted?

Max- The schedule 10 pipe I'm using has a wall thickness of about 1/8". Still probably twice as thick though.
From the pictures of T-78 turbine housings I've seen they look similar but the "dual a/r" isn't nearly as drastic.

 

i have had all these problems before,

what i found the size of the runners are the biggest problem, i went to 2in ID runners and all my problems went away, i can run 7psi all day long with a 1.32 P trim rear and a 66mm comp wheel,

Dale

 

So your primary runners were what size and your wastegate runners are what size?

Does your manifold look like the one in the beginning of this thread or of different design?

Did you use 1 or 2 wastegates?

Im sure others would like to know how to stop this boost problem!

 

Ditto

 

IGY and 10sec rx7 are you guys around? It would be great if you guys would answer our questions.

Thanks

 

Riceracing quote-
Then modify your Turbine housing and put the WG right of it ! Your manifold is beautiful, do not scrap it or modify the design you will not be able to fit any angle of pipes into the existing room you have they way you have designed the manifold.

This is an interesting idea that I had not heard of being used on an aftermarket turbo before. Sounds similar to what I tried on my stock hybrid turbo, except could be done w/ out the restrictive bends before the WG my design incorporates- if there is room in the engine bay.

My WG is HKS GT 60mm the turbo is stock '89TII hybrid w/ 60-1 Hi Fi compressor and T4 "O" trim exhaust wheel clipped 15 degrees in a bored stock housing w/ both the housing's scrolls slots widened from stock 5mm to 10mm all the way around.



Didn't stop boost creep.

Turbo is now being bored for T4 "P" trim exhaust wheel.

I may also make a SS divider that fits flush w/ the WG holes in the turbo backplate and up all the way up the pipe to the WG valve to keep the exhaust pulses divided- but so far spool-up had NOT been a problem.

I undercut and radiused the turbo runners in front of the WG hole ~ 1/2" and tapered the rear of the upper WG holes in an attempt to get some angle to the WG holes intersection w/ the exhuast runners.







Here you can see the scroll's slots are twice as wide as stock.



Another Riceracing quote-
Mainly cause I had a restrictive turbine in a hybrid before as Max was eluding too and it was a big boost spike in the mid range, not a constant "creep" linear with revs like you are experiencing.

This is not the boost creep that I am experiencing. W/ the pictured set-up no matter where the WG was set (.8-1.2 KG/cm2 spring) it would creep to 1.3-1.4 KG/cm2 by 5,000rpm and over 1.5kg/cm2 after 7,000rpm. It was still pulling harder at 8,000rpm (once I figured out my ~7,000rpm stumble was max duty cycle on my 720 and 1600cc inj....Walbro pump choking out).

 

BLUE TII

Before you put in the external gate, did you have a mid range spike folowed by a drop off ?

What type of exhaust do you run ?