Twin turbo BBC no wastegates

[dnewps]

I have nearly all of the parts for this project. 555 ci. I would really like to do this with a blow through carb AND no wastegate if possible. It’s going under the hatch so all of the additional plumbing for wastegates is just more heat. I have water jacketed turbo housings.

The old turbo set ups had a hole drilled in the turbine that would bleed pressure directly into the exhaust pipe. Can anyone explain how that worked? Does the boost curve look like a procharger?

 

[RaceTec]

Hey Barry @obnoxious001

 

[rivermobster]

I'm interested in how this works...

 

[obnoxious001]

I have nearly all of the parts for this project. 555 ci. I would really like to do this with a blow through carb AND no wastegate if possible. It’s going under the hatch so all of the additional plumbing for wastegates is just more heat. I have water jacketed turbo housings.

The old turbo set ups had a hole drilled in the turbine that would bleed pressure directly into the exhaust pipe. Can anyone explain how that worked? Does the boost curve look like a procharger?

Like you said, it would bleed off pressure directly into the exhaust. Gale Banks did that on his systems, coupled with low boost meant the engine was lazy on the bottom end. I don't have a map of the boost curve.

 

[rivermobster]

Like you said, it would bleed off pressure directly into the exhaust. Gale Banks did that on his systems, coupled with low boost meant the engine was lazy on the bottom end. I don't have a map of the boost curve.

What happens at idle?? Built in EGR??

 

[Eliminator21vdrive]

What happens at idle?? Built in EGR??

The hole was in the hot side bypassing exhaust from impeller straight threw to exit (through the snail) and could be adjusted with plugs and different size holes.

 

[rivermobster]

The hole was in the hot side bypassing exhaust from impeller straight threw to exit (through the snail) and could be adjusted with plugs and different size holes.

So just from one side of the exh impeller to the other side of it, yes?

 

[obnoxious001]

What happens at idle?? Built in EGR??

The bypass holes were drilled at an angle. Think of how crankcase vent tubes are welded into exhaust headers, so the exhaust extracts pressure from the crankcase. At Banks we had a few race versions that had no bypass, but then from 1/4" to 5/8" in 1/8" steps if I recall.

 

[dnewps]

The bypass holes were drilled at an angle. Think of how crankcase vent tubes are welded into exhaust headers, so the exhaust extracts pressure from the crankcase. At Banks we had a few race versions that had no bypass, but then from 1/4" to 5/8" in 1/8" steps if I recall.

Do you know if the boost curve is gradual like a centrifugal blower with the hole in the turbo?

 

[Racey]

Do you know if the boost curve is gradual like a centrifugal blower with the hole in the turbo?

I'll tell you how the boost curve looks, lazy as fuck and shitty

Wastegates in a gentry style turbo aren't that much added plumbing, and totally worth it.

Those old Ray-Jay drilled housings ran like basset hounds. Not even remotely comparable to a modern wastegate setup.

What waterjacketed housings do you have? fabricated ones with no wastegate provision?

 

[farmo83]

I'll tell you how the boost curve looks, lazy as fuck and shitty

Wastegates in a gentry style turbo aren't that much added plumbing, and totally worth it.

Those old Ray-Jay drilled housings ran like basset hounds. Not even remotely comparable to a modern wastegate setup.

What waterjacketed housings do you have? fabricated ones with no wastegate provision?

Why is this the case ? The new EFI set ups don't have to move the fuel as well ?

Just trying to learn ?

 

[Racey]

Why is this the case ? The new EFI set ups don't have to move the fuel as well ?

Just trying to learn ?

Because of the Turbo Polar (the efficiency map of the turbo to extract energy and convert it into boost) it's a huge detriment to be constantly bleeding exhaust energy down low, mainly at the entry point of the turbo operation window (think 3000 rpm or so)

You want all energy you can get into that turbine down low and then you can dump what you can't or dont want to use up top. If you are bleeding exhaust energy down low it just makes it that much harder to build hp and torque in the areas you want it the most in a boat that doesn't have the luxury of multiple gears.

Then when you are talking EFI you can have the computer control the wastegate giving you even better flexibility in your design, with the addition of the compressor not having to the fuel mass it makes a huge difference in turbo response. Also gives you the ability with the push of a button to cycle boost levels for different fuels etc. Not all ECUs are capable of taking advantage of these abilities, but the good ones are.

But really even carbureted with a spring set wastegate will be leaps and bounds over no wastegate and a bleed hole.


The EFI is really the bees knees, but it does cost $. I just finished a round of multi map boost control for a customer on a turbo car with a Motec box, we programmed 3 boost levels, so with the touch of a button you can go from 6 lbs, to 9lbs, to 12lbs of boost. No matter what condition you attack the load or throttle i think our biggest boost error (boost we want, vs actual boost delivered) was around 3kpa (around 0.4 PSI) for about 1/2 of a second before it locks into target by manipulating the waste gate controller dozens of times per second

 

[dnewps]

I'll tell you how the boost curve looks, lazy as fuck and shitty

Wastegates in a gentry style turbo aren't that much added plumbing, and totally worth it.

Those old Ray-Jay drilled housings ran like basset hounds. Not even remotely comparable to a modern wastegate setup.

What waterjacketed housings do you have? fabricated ones with no wastegate provision?

Problem is...this boat has a hatch. Wanted to try to avoid extra heat from the wastegate plumbing. I have fabricated, stainless water jacketed housings that go over a standard turbo housing. Would love to find a turbo with integrated wastegate and water jacketed housing. Trying to make 900-1000 on 8 lbs

 

[Racey]

Problem is...this boat has a hatch. Wanted to try to avoid extra heat from the wastegate plumbing. I have fabricated, stainless water jacketed housings that go over a standard turbo housing. Would love to find a turbo with integrated wastegate and water jacketed housing. Trying to make 900-1000 on 8 lbs

Yeah i would start hunting down some used gentry/race aero housings with integrated wastegates.

Those "jacketed covers" that just go over a normal housing are not really ideal inside a hatch as the turbo is still glowing red hot under them.

 

[dnewps]

Been looking for years...nothing. Marine diesels have both but I don’t know which ones will support 900-1000hp???

 

[farmo83]

Doesn't Brummett make water jacketed housings ?

 

[rivermobster]

Been looking for years...nothing. Marine diesels have both but I don’t know which ones will support 900-1000hp???

@OCMerrill

 

[Racey]

Doesn't Brummett make water jacketed housings ?

Yes, he owns all the race aero, gentry, and now his newer Brummett castings

 

[dnewps]

Yes, he owns all the race aero, gentry, and now his newer Brummett castings

Yes he does. They are 6k each. Can’t swing that for this project.

 

[rivermobster]

Yes he does. They are 6k each. Can’t swing that for this project.

So........

Procharger? Maybe?

 

[Skifree]

I have an extra Rajay turbo set with additional extra gale banks exhaust housings, both sets of housings have the bleed holes in them. For sale