Turbine Housings

[LemansWagon]

Oh and about the waste gate. I was thinking that since I will be running low boost that if the turbine housings are too small I will start to see boost creep at higher rpms before the motor chokes off. If that's the case than I was thinking a big external wasgate with good size piping could bleed the excess exhaust, keep the boost low and allow the exhaust to breath better possibly extending my rpm capability.

On second thought though, it is probably really a band aid fix that would cost the same as upgrading to a stage II or III turbine wheel & housing. Big aftermarket wastegates are expensive.

 

[charlief1]

I didn't get the chance today to take measurements. Been a PITA getting anything done it seems. The 84-86 exducer is smaller than the carb/turbo design but bigger than the 86-87. You shouldn't have any issues with running any of the SFI hot sides but the 86-87 is the best overall. It has the best flow and is still got a decent AR rating. Going with a bigger Ar will just make it harder to spool. More weight to move afterall.

 

[LemansWagon]

Thanks. The A/R on my 84-85 is .63 too. Whenever you get the chance to take those measurements is fine. I am certainly not doing anything to it in the next few days. Still in the research stage. Probably do it over the winter rather than take the car off the road now. But I was holding the turbos in different places in the engine bay to start visualizing how I might mount them and damn they'll look good.

 

[charlief1]

Thanks. The A/R on my 84-85 is .63 too. Whenever you get the chance to take those measurements is fine. I am certainly not doing anything to it in the next few days. Still in the research stage. Probably do it over the winter rather than take the car off the road now. But I was holding the turbos in different places in the engine bay to start visualizing how I might mount them and damn they'll look good.

You're in trouble now. That's how I started.:biggrin: Been doing research from the time I joined till now and I think I have it figured out finally. We'll see when I get the car together. I've had the car for 3 years now and it's finally in the shop getting repaired. The most I've driven it is onto the trailer and off. Kinda sucks but I just didn't have the space to work on it until now.:redface:

 

[LemansWagon]

Charlief1, did you get a chance to measure the turbine wheel yet?

 

[charlief1]

It's been a very busy week and I haven't had a chance yet. Send me a PM with your email and please be patient. I'll do it as soon as I can.

 

[dr_frankenstein]

I see where things have been getting mixed up in our communication now. This is how I understand it:

The term turbine exclusively refers to the exhaust side. The inlet side is not really a turbine but a compressor or impeller because a turbine is "driven" by a fluid. Or in other words the fluid does work on the wheel. Whereas an impeller/compressor does work on the fluid by transferring kinetic energy and also compressing it in the case of a gas. And the terms inducer and exducer do not refer to compressor and turbine sides exclusively. Both sides of the turbo actually have an inducer and an exducer but they are opposite. On the turbine side the exducer is the smaller, or minor diameter of the wheel where the exhaust gas exits and the inducer is the larger, or major diameter, where the exhaust gas enters. On the compressor side it's the exact opposite with the inducer being the minor diameter and the exducer being where the compressed gas exits.



So what I've been unsuccessfully trying to find out is both the major and minor diameter of the turbine wheel on an 86-87 turbo to see how it compares to the wheel on an 84-85 turbo. See how big the difference really is. I have the 84-85 but can't find the dimensions of the 86-87 anywhere on the internet. Up until now I thought the turbine side of the 84-85 and 86-87 were identical since they were both .63 A/R. So I want to know the radius of both wheels so I can calculate the percentage difference in area inside the housing. This percentage difference should be proportional to the flow capability of the respective turbine housings and give me an idea how much more cfm the exhaust turbine of an 86-87 can handle over the 84-85.

there the same. difference is in compressor housings. your way over thinking this.

A.j.

 

[LemansWagon]

Being an engineer I have to smack myself occsionally for overthinking. My friends call me on it all the time LOL. So then those exhaust turbines from my 84-85 should be just fine matched with the T4 compressors on my big block if they can handle a 3.8. They'll only be seeing 3.3 liters on the 396. Do you know what HP level those turbines are good up to? I just don't want to choke my 396. I love the way it revs.

In the car craft article this month they used 56 trim .58 A/R turbines on the cheap ebay turbos on a mild 350 and had major problems controlling boost. But they never gave the turbine wheel dimensions. I think they were much smaller than the .63 GN turbines. They looked it.

By the way, I just nabbed a set of SS turbo headers for a big block off ebay. So the plan is now in motion. Next summer my big block chevelle will be twin turbo! Anybody want a practically brand new NOS 150 carb plate system : )

 

[dr_frankenstein]

the issue is going to be how big the T4 wheels are. You cannot readily assume a bigger wheel will make better or more power. if the small T3 Turbine cannot find enough energy to move the overly sized T4 wheel then your only hurting performance or you could have the opposite and totally plug up your system with a tiny wheel. Many hybrids I have built never performed the way I had hoped, while being a bigger unit... it was only better then the previous unit if I pushed my boost into the stratosphere... which was not helpful as i was limited on boost. the small .63 turbine should be fine for the most part... but expect creep issues and boost control issues higher in the boost and RPM range. For the most part, the car craft people had issues because of inferior housing and wastegate design. Sitting the way they are, 2 stock 84-85 turbos will easily choke the big block. you would be close to enough for lower RPM stuff with 2 stock 86-87 units. but I would reccomend using 2 TA49s or even 2 TA60s to make any kind of real power.

Also, you have to confirm that the T4 has the same shaft size, as I havent found many diesel T4 turbos to have the Standard shaft and not the regular larger T4 shaft.

oh yea.... dont forget most aftermarket headers use the 4 bolt flange.... unlike the buick 3 bolt.

A.j.

 

[LemansWagon]

I'll have to measure the shaft. I hadn't thought about that. I have 2 TO4B wheels & housings but only one is big enough. So the other wheel I'll have to buy and have the housing machined to match. The measurements on the wheel I have already are 2.19 minor & 2.75 major which matches a V-trim. It's not one of the T4's with the big 3" diameter wheels. Supposedly good for about 350-400 hp which is perfect. I'm only looking for 500 at the wheels.

I have contacted the guy at g-pop shop about it and he's been a big help. Has the wheel and can machine my housing.

And the headers I got have T4 flanges but I want to make a 90 degree adapter anyway so the turbine outlets point straight back. I think I'll just ditch the elbows and use external wastegates after seeing the car craft article so that simplifies the exhaust fab. I also have a selection of both ford & buick .63 housings so I can use either type of flange. I was leaning towards the 4 bolt ford because I think they are easier to come by if I decide I need a bigger turbine wheel.

What's a decent external wastegate to get that won't bankrupt me?

 

[dr_frankenstein]

hmmm.... good question.....

I liked to use the delta gate back in the day... ut any of the TiAL units are very very good.

but i would know what would be worth it for cheap... i hear alot of the ebay knock offs are hit and miss ... but for the price... might be worth a shot?

G-pop Shop? your in great hands.... them boys will get it all taken care of for you.

A.j.

 

[LemansWagon]

For this project I am more willing to part with my money for something of good quality. I just don't want to spend it needlessly. It's not like my budget wagon project we were discussing in another thread where I am trying to use whatever I have where possible. I have too much money tied up in this Chevelle to risk with unknown products. I have twice as much in the engine alone as I'll probably spend on the entire wagon project. Don't want to toast this engine because I wouldn't spend a few extra bucks on a better wastegate. Penny wise & pound foolish!

 

[porsches4lunch]

OK, finally had time to peruse the whole thread. I see what you are saying. I was concerned because I know that the mustang guys using t-bird t3's (same as 84-85 GN) on 351's are limited to less than 5500 rpm. But I wasn't thinking....that's most likely the compressor not the turbine. With the T4 compressor that would be moot.

I do plan on spinning it to 6k but no higher. It'll go to 6300 right now but it's not any faster that way so I shift at 6.

My buddy has a 351W with two stock 87 turbos. It spools up right away and does not run out of steam at all.

 

[charlief1]

My buddy has a 351W with two stock 87 turbos. It spools up right away and does not run out of steam at all.

Thank you.:smile: This is what I've been trying to tell him.:biggrin: