While it would still take some fab work, here's a diy for twin T-76's on a (yikes) street car http://www.quicktimeperformance.net/store/cart.php?m=product_detail&p=29

 

Holy sh*t, that's ingenious! What a simple concept. Thank you for sharing it. I know what I'm going to do this weekend.

 

I've been scratching my head as to how I could reduce the internal size of my turbine housing... but I've obviously been thinking along the lines of over-complication.

When something is as simple and beautiful as a blanking plate... it has to be right.

Well done my friend... and thankyou for sharing your genius with us.

Now where's that HT60 that I thought was too big..?

 

wow this is really cool. you could "wastegate" the 2nd chamber to open at like 1 psi before full boost, and thet at full boost have another wastegate open to atmosphere.

 

I just finished doing this. It works!

I just finished making a flange like that for my H2D and it feels like a different turbo! I don't have a fancy computer like 302tt, but I can tell you that I'm seeing full boost as soon as I mash the throttle, no more lag! The needle flips to 5 psi much quicker now. Before it would roll over, now it snaps over. The turbo also spools under partial throttle. It never did that before.

I need to run some tests to see how much sooner the turbo spools, but it made a huge difference.

Great info 302tt, you saved me from buying a new turbo.

 

re blocking one entry

Damn 302, youve let the secret out.

couple of things to consider though

1, it would be best to block the entry closest to the center cartridge as it drops the running temp of the compressor a fair bit

2 its highly advisable before everyone runs out and does this to plumb a 50psi gauge into the exhaust manifold to check pressure before and after as its quite possible to greatly increase exhaust manifold pressure and cause durability problems for the exhaust valves and introduce detenation if your not careful

3.watch boost the first time you drive the car as its possible that if your wastegate wasnt overly large to start with you may overboost to the point of losing your motor

4. the idea of a swithable vane has merit, but if your going to go this way with a manual gearbox try and incorperate a clutch switch so that on gear changes the valve shuts momentarily as this will aid pressure rise when the throttle is cracked open again

302, is it possible for you to data log your exhaust manifold pressure with the plates in and out for comparison ???

cheers

 

Re: re blocking one entry

this is the first thing that crossed my mind when i read this thread...

 

Subscribing - cool stuff!

 

Some more data

Logged a decent 3rd gear WOT tonight with the 0.5 A/R for comparison against the 1.0 A/R. Data below - its still totally awesome. . Starts making boost at 2400rpm then up to 11psi by 3800rpm. If I wanted the boost to keep climbing I would probably have to go to a larger A/R (or a valve set-up) since its starting to get choked at high rpm (boost starts dropping slightly).

02Z28M6 Great news - I'm glad it worked out for you too.

Mark360 - sounds like you have tried this before. I cant log pressure before the turbine. I bet its kina high. What would an acceptable pressure be anyway? I have no idea. As long as I can spin the tyres at 50mph I'm happy

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Great news..... I love this board...

 

Re: Some more data

I wouldn't worry about pressure so much. I'd just have a valve based on either boost pressure(use a wastegate actuator to open the valve) or RPM. A solenoid that opens the valve could be opened at like 5000rpm or whenever your turbo would be spooled without the divider plate. Or if using the wastegate control just set the gate to open slightly before max boost pressure.

 

Mark360 - sounds like you have tried this before. I cant log pressure before the turbine. I bet its kina high. What would an acceptable pressure be anyway? I have no idea. As long as I can spin the tyres at 50mph I'm happy

Usually a rule of thumb as far as back pressure goes in the Supra community is when a gauge is plumbed into the manifold/header if you get a pressure reading that is double boost pressure you are running you have too small a turbine housing.

 

genius, simply genius

 

but isn't a rule of thumb to runn way to big of a turbo on your supra anyways

 

i think this would work great for traction issues
you can adjust your lag cool

 

If you really wanted to experiment with this you could start drilling a hole in the other side of the blockoff plate and adjust the backpressure that way too. Once you reached an acceptable point on the backpressure quit enlarging the hole in the blockoff plate. :shrug:

 

I run a .68 a/r with a p trim on my 67 mm turbo and made 518 rwhp/475 rwtq @ 19 psi, but I made 450 rw/418 rt @ 16 psi and 552 rw/ 508 rt @ 25 psi. All these run were at 11.6 to 12.0 to 1 a/f's and the first two were still pulling hard at redline and the third had started to drop. My redline is 6500 rpm and my hp/psi ratio had started dropping the farther I pushed it. I will find out soon if my .81 housing will change this.
The block off plates are a good idea on a log style or non divided header making otherwise too big of turbine housing useful and even appealing. I couldn't run one on my 7M-GTE or a V6 we have with a big single that one half of the turbine flange is being fed by one bank of the engine and the other side is being fed by the other bank. I have been looking into going to a GT42 with a 76 mm wheel and this would make a mock up turbo with a T6 flanged 1.34 a/r housing I have an interesting option instead of buying a 1.01 T4 flanged housing for it. The only thing I can see that you will have to be careful on is when you take a 1.00 a/r T4 turbine housing and remove half of it can you really say this becomes a .50 a/r housing? Bottom line is the achieved results were the results he was after and there has been some more great idea's to come out of this discussion.
Sean
CWF Dyno Services

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Another chart for drop off comparison.

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i had the same idea a while back and even made a topic question of it, but in the end i guess i did not do it to show evidence of it working. i got no replies. the real bummer is that my detroit turbo is single tang. any twin scroll detroit turbines out there?

 

The 60 series Detroits used twin scoll T6 turbine housings from a 1.15 and 1.22 wastegated housing to a 1.22, 1.28, and 1.34 non wastegated housing.