- Thread starter
- #41
ok got the mixer mounted, oil inlet adapter made, and oil drain adapter made. I will cut the 2" holes tomorrow and make the intake tubes.
propane turbo build
- Thread starter motoman426
- Start date
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Hmm I'm curious if this is actually going to allow the WG exhaust to flow freely enough or if you're going to boost creep.
- Thread starter
- #43
it should flow pleanty the waste gate only opens when it gets a certain psi and dumps the excess so all it has to do is really flow a small amount because it is a small port.
I think you'll be surprised exactly how much air is flowing from the WG. Not to mention the exhaust is being forced into a wall and then it has to try to flow out the side through the slot. But like I said, we shall see.
Also, maybe I missed it. But what are the specs on the turbo? How much boost do you plan to run?
Also, maybe I missed it. But what are the specs on the turbo? How much boost do you plan to run?
- Thread starter
- #45
well got 90% of it done need one more 90 pipe and I will be done and ready to test tomorrow hopefully
rover67
SILVER Star
I also wonder it the waste gate setup will allow enough flow. I guess you'll know when you run it.
interesting way to do it anyways.
interesting way to do it anyways.
- Thread starter
- #47
Well if it dosent I will just unhook it and do a external waste gate
ntsqd
technerd
A blow-off valve will allow you to keep the 'wheel spooled up while shifting. Set the BOV to come in a bit before any WG.
Could you go into more detail? I'm not really sure what you're saying he should do. A BOV and WG serve extremely different roles.
What are you using for the manifold plate? Looks like a manufactured part. The bottom 1/3 of a stock carb?
- Thread starter
- #51
you are right they do serve two total different purposes and all a BOV really does is keep from "barking" the turbo. allowing the pressure to dump off when it senses vacume
- Thread starter
- #52
well actually it is a 2 barrell holley adapter that I modified to fit. it worked really good the rest is just factory impco parts
- Thread starter
- #53
well got it done and hopefully tomorrow tune it in a little and run some exhaust and put a oil restrictor in and I will be ready to go wheeling this weekend and break something
YouTube - jodys turbo?
YouTube - jodys turbo?
How much boost?
And a burnout vid is required!
And a burnout vid is required!
- Thread starter
- #55
i dont know yet I have not got gotten a cheap boost gauge yet if I had to guess I would say around 10 but I could be wrong. I should have some good videos of this weekend a lot o 
at a private ride so it should be interesting
at a private ride so it should be interesting
ntsqd
technerd
Actually they don't have different roles, they just do the same job differently, with different resulting by-product effects. The overall job of both is to control the maximum boost level. One does it by by-passing the turbine wheel so that the exhaust energy applied to it is reduced thereby reducing the maximum boost possible. The other does this by venting some boost to either the atmosphere or to upstream of the turbo. Can think of the BOV as being the same as the blow-off safety valve on an air compressor and the WG as being the compressor's pressure switch. One vents excess, the other turns off the power.
The advantage of using the BOV as the primary boost control is that it unloads the compressor wheel while still applying full exhaust energy to the turbine wheel. That keeps the turbo spooled up. W/o a BOV the closing of the throttle sends a pressure shock wave back towards the compressor wheel. If severe enough or done often enough it can be a "negative performance feature" for the compressor wheel's vanes. If the BOV is sized close to right the turbo may still be able to over-boost the engine.
With only a WG to limit boost when the throttle plate is closed during a shift you get that destructive pressure shock wave and you get a "dead-headed" compressor. Two things happen with a dead-headed compressor, the air gets super heated - which isn't so good for other engine parts, and it acts like a brake on the turbo shaft - causing it to "un-spool".
By using both methods you can control the normal max boost level with the BOV and pick up the benefit of the turbo staying spooled-up in shifts, and then use the WG at a setting slightly above the BOV's setting to insure that you don't go into an over-boost condition.
Interesting, I've never heard anyone use a BOV as a way to limit boost. Well, I suppose centri superchargers sort of do at idle, but again thats entirely diferent
Nearly all turbo systems use both a WG and a BOV but for extremely different purposes. The purpose of a WG is to bypass the turbine wheel like you say to limit boost. The use of a BOV is to vent the air between the compressor and the throttle plate when the plate closes. This prevents compressor surge. Interestingly enough some motorsports do not allow the use of a BOV.
I can tell you an issue with running a BOV as a means to regulate boost on an average car. On most vehicles that would screw up air metering. It would essentially be a large leak of already metered air thus causing the vehicle to run rich. Thats assuming you run a MAF, I suppose a speed density set up might not be effected in the same way.
I've never heard of such a set up. Do you have any information about it? I'd be interested in reading up on it.
and running a bov with draw through setup is a big no no your dumping the propane and air into the engine bay
Ah you bring up another great point. Since air is never trapped between a plate and the compressor in a draw through set up a BOV is not required to stop it from compressor surging.
ntsqd
technerd
The ricer types vent the BOV to atmosphere (for the sound?), but I did mention that it can be (& should be, for your reason) plumbed back into the intake upstream of the turbo but downstream of the air metering device.
Compressor surge in that situation is caused by dead-heading the compressor due to the closed throttle plate(s). Preventing the surge requires that the over-boost condition be vented somewhere. It is called surge, but in my mind it is really cavitation. I'm just not sure how you cavitate air.
Because of the inertia of the turbine wheels and the two gas columns a WG can't react fast enough to prevent the over-boost/compressor surge that happens during a shift. It is that operation mode where the BOV is the better boost limiter.
With a draw-thru no matter where you vent a BOV to it's going to cause problems, and since comp surge isn't very likely in that set-up I don't see a need for a BOV. Somehow I missed that this is a draw-thru system?
Compressor surge in that situation is caused by dead-heading the compressor due to the closed throttle plate(s). Preventing the surge requires that the over-boost condition be vented somewhere. It is called surge, but in my mind it is really cavitation. I'm just not sure how you cavitate air.
Because of the inertia of the turbine wheels and the two gas columns a WG can't react fast enough to prevent the over-boost/compressor surge that happens during a shift. It is that operation mode where the BOV is the better boost limiter.
With a draw-thru no matter where you vent a BOV to it's going to cause problems, and since comp surge isn't very likely in that set-up I don't see a need for a BOV. Somehow I missed that this is a draw-thru system?
