garret BB only 23psi??
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I've gotta say, I agree with Hiflyer746. I've problems with the argument of more volume, less boost. You are still dealing with the same open system. The turbo is supplying more air than the engine is consuming, which creates the pressure buildup. If you supply more air, you get more pressure. The system is the same volume, and the engine is not consuming more air. The turbo may be supplying more air efficiently, but that air is going into the same system where the pressure is measured.
And as a side note: The cylinders are constant volume at bdc. The amount of air in the cylinder is strictly related to pressure. High pressure, more air. Low pressure, less air. The argument of a turbo supplying more volume at less pressure doesn't work here either.
And as a side note: The cylinders are constant volume at bdc. The amount of air in the cylinder is strictly related to pressure. High pressure, more air. Low pressure, less air. The argument of a turbo supplying more volume at less pressure doesn't work here either.
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so the test. . .
So the test here is to hook up your boost line to the engine side(as opposed to the turbo side) so you can find out how efficient your turbo "System" actually is. I agree that with the BB turbo to the stock turbo. . . you'll probably see some improvement. But I think that you'll see a bigger improvement by matching the system with the turbos capabilities. But there is a point where no matter what you do. . . you won't be able to cram any more into the engine. That restriction is the heads. But I don't think we'll be reaching that any time soon
Tim
Tim
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From: Dallas, Texas
Turbulence is a great way to explain it...and so is cavitation.
The air doesn't really back up and stabilize through the intercooler in the condition we are talking about. There will actually be a drastic drop in pressure/volume when a turbo begins to top out.
Fuel would be an issue, especially with a 40 hp tune. The only thing that doesn't make a whole lotta sense is a BB turbo not spooling very quickly.
The "stacking" effect that Muktown explained is right on. A BB/large turbo can do that-quickly. The smaller ones can not.
The air doesn't really back up and stabilize through the intercooler in the condition we are talking about. There will actually be a drastic drop in pressure/volume when a turbo begins to top out.
Fuel would be an issue, especially with a 40 hp tune. The only thing that doesn't make a whole lotta sense is a BB turbo not spooling very quickly.
The "stacking" effect that Muktown explained is right on. A BB/large turbo can do that-quickly. The smaller ones can not.
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From: Dallas, Texas
Just caught BigCountry's post.
ANy air stacking against a closed valve will be re-routed to an open one. When things really get going that stacked air goes right back out of the compressor inlet.
So let's turn this into a supply and demand question. If the engine can not accept the volume pressure than there is definately an imbalance in the system.
The wastegate is supposed to relieve drive pressure at about the same time the motor can't accept any more air - this is our purging problem. You force the system into an overboost situation and you have other issues.
If volume didn't matter througout the entire loop of the system, then compressor and tubine mapping would be moot. There would be one turbo for all applications. Fill the cylinder faster, efficiently, and have some weight behind it.
ANy air stacking against a closed valve will be re-routed to an open one. When things really get going that stacked air goes right back out of the compressor inlet.
So let's turn this into a supply and demand question. If the engine can not accept the volume pressure than there is definately an imbalance in the system.
The wastegate is supposed to relieve drive pressure at about the same time the motor can't accept any more air - this is our purging problem. You force the system into an overboost situation and you have other issues.
If volume didn't matter througout the entire loop of the system, then compressor and tubine mapping would be moot. There would be one turbo for all applications. Fill the cylinder faster, efficiently, and have some weight behind it.
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this is some good reading. the boost guage is in the y-pipe going into the intake so these measurements are after all the pipes and cooler. the way some of you are thinking is the way i was also. i will be getting more fuel to spin the turbo this week and will be able to see the difference. i am also going to take out the tow program and see what it does to it today. thanks guys again.
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stacking
Your saying that too much stacking, and it goes out the intake. That sounds like a compressor stall. The compressor isn't designed for that kind of pressure. So the bigger turbos, or the different wheels designed for more boost handle more boost, and therefor you see more boost. That is as long as you have the fuel to drive them. I am sure when I put my H2E in with stock injectors, and just a 50hp BD chip, that I actually lost pressure. I didn't have enough energy to turn the bigger compressor. But with more fuel. . . there is enough energy to spool the bigger compressor. I don't know much about the BB turbo, as far as size. But I would imagine that a BB version of the stock turbo would outperform the stock turbo. But when you fuel your engine more, you should start seeing more power and boost with the bigger turbo. I still don't agree with less is more with the bigger turbos.
But, you're all making me think!
Tim
But, you're all making me think!
Tim
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From: Dallas, Texas
Somebody made me think, I made somebody think....all in all a good day.
It's all about being able to stuff air into a cylinder, the little ones aren't as good at it as the big ones are.
Yes, the stacking is the stall. A high volume turbo can push more air into area than a smaller one, without the loss.
Now my brain hurts, time for a Sunday Budweiser...i'll have one for everyone.
See you on the boards Monday.
It's all about being able to stuff air into a cylinder, the little ones aren't as good at it as the big ones are.
Yes, the stacking is the stall. A high volume turbo can push more air into area than a smaller one, without the loss.
Now my brain hurts, time for a Sunday Budweiser...i'll have one for everyone.
See you on the boards Monday.
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Joined: Jan 2004
Posts: 1,679
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From: Parker, CO
Just to get back to the topic for a second. Running a 40hp tow tune won't give big boost numbers on a BB turbo. The exhaust housing is larger, and he simply doesn't have the exhaust gas volume with a mild setting to get that turbo to spool up.
There, get more fuel with a hotter chip and you'll see your boost gauge climb.
BTW, today heading up towards Eisenhower Tunnel from Silverthorn in Colorado gave me 22#'s of boost at half throttle on the DP-Tuner 80 hp econo setting. That was from a near complete stop (traffic from a wreck), to throttling up about a 6% grade.
There, get more fuel with a hotter chip and you'll see your boost gauge climb.
BTW, today heading up towards Eisenhower Tunnel from Silverthorn in Colorado gave me 22#'s of boost at half throttle on the DP-Tuner 80 hp econo setting. That was from a near complete stop (traffic from a wreck), to throttling up about a 6% grade.
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