Turbo options on a B engine

[RadioFlyer]

If one were to install an '82-84 turbo in a b20 to replace the old external wastegate unit, would the APC system be required? Would you guys recommend installing a Mitsu TE-05 over an early Garrett unit?

[DrewP]

Just the turbo you wouldn't need APC one way or another, it's dependent on the boost pressure you want to run.

I'd recommend not using the TE-05, unless you have at least one good one. They are extremely difficult to find rebuild parts for, and the turbine housings all tend to crack around the wastegate flap and pivot, plus you'd have to come up with how to get cooling water to it and back.

[RadioFlyer]

Cool, thanks Drew. Would the APC help? And is it standalone or would I have to change the ECU, etc?

[DrewP]

APC is standalone, all it does when knock is detected is lower the boost pressure. If the engine starts knocking, boost gets lowered until knock stops, then is listens for the knock sensor again.

If there is enough boost that it'll knock consistently it'll just sit on the threshold of knock, it's not a particularly safe way to control knock.

T5 on the other hand can vary fuel mixture, ignition timing, and boost pressure all simultaneously to actually stop knock events, rather than just lower performance until the knock subsides.

[Luke]

APC is standalone, all it does when knock is detected is lower the boost pressure. If the engine starts knocking, boost gets lowered until knock stops, then is listens for the knock sensor again.

If there is enough boost that it'll knock consistently it'll just sit on the threshold of knock, it's not a particularly safe way to control knock.

T5 on the other hand can vary fuel mixture, ignition timing, and boost pressure all simultaneously to actually stop knock events, rather than just lower performance until the knock subsides.

You'd also have to drill and tap the block in appropriate place to add a knock sensor. I remember people doing that back in the 90's, when APC was still relatively new, but I don't think it would be worth the trouble to hook up these days. Just run good gas and set a reasonable boost limit.

[Crazyswede]

Some people used to put the 8v 900 exhaust manifolds on the B motors so that they could get rid of the B style blow off valve and run the later turbo setup. These manifolds were all prone to cracking so it might be a big of trick to find one.

[RadioFlyer]

That's what I was considering. The H manifold look the same as the B manifolds tho except there is a block off plate where the wastegate pipe would go. Is there any other difference? Turbo port size?

[99Super]

Nope. They are the same. I'm one of those people who tapped the block of my B motor to run APC and ran the H turbo and manifold. System worked well enough up to 12-13 lbs of boost with a 900 IC. Now I have T5.

John

[Geoff]

I'm doing some parts clean up/organisation. It turns out the B and H turbo manifolds, while interchangeable along with the corresponding turbo, are different castings. The B manifolds crack at the junction where the #1 and #2 runners meet. The H manifolds have some webbing at that junction. There are a number of other subtle differences. The H manifold retains a number of the bosses that the B manifold uses for tapped holes, heat shield studs, etc.

The B manifolds I have probably came from '78 and '80 cars while the H manifold I have probably came from an '83.

[Crazyswede]

The h manifolds crack too

[99Super]

The h manifolds crack too

...especially between the 2 and 3 ports. According to my old machinist, it's because the manifolds warp under the high heat.
Years ago, he welded mine and reground the flanges square. It was fine for nearly 20 years after that...

[Geoff]

Yup, that's where the H manifold I have is cracked!

[Crazyswede]

probably the best way to go from a longevity point of view is to build or have built a log manifold out of heavy gage stainless. Jon Williams builds them out of some real thick wall SS and they are beefy. He will have to chime in on the schedule of tubing he uses.

[Jon1]

I use schedule 40 IPS pipe for my headers. Equal volume headers were made out of 1-1/4" pipe and fittings, log manifolds were made out of 1-1/2" fittings into 2" pipe. I am currently working on a log style for my current SPG build.

BTW, pipe is different from tubing. Tubing is by outside diameter, Pipe is by nominal inside diameter. The inside diameter changes with the schedule (thickness). Pipe is larger than tubing by stated size.

[99Super]

I think Seth (crazyswede) designed a manifold to be built out of steam pipe like that. It was years ago iirc. Seems like a good idea, but welding the stupid crack is a lot cheaper.
I'd love to see how one of Jon1's manifolds turns out!

John