PSI is a measure of restriction. How much air mass does it flow at each pressure increment?
1983 Oldsmobile Cutlass Supreme Sedan LS Turbo Build
- Thread starter GroceryGetter83
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PSI is a measure of restriction. How much air mass does it flow at each pressure increment?
I don’t believe I’ve seen pressure/flow charts for these turbos. I was told the cover was good for 50-75 hp, not sure if crank or wheel. We will see how much I pick up at the track
Interesting to know the answer to what you’re asking, but at the end of the day knowing the answer is worth diddly squat.
If Chris can launch the car consistently and dial the tune to another 9.6, then he can see the boost difference to determine how much more hp the cover is worth.
And I say wow is that a lot of work to not go faster haha. Much easier to calculate the total it’s worth (increases) rather than at each pressure increment.
Saskatchewan Yoda was trying to say, Psi means nothing, an efficient air pump (motor) will have less boost (psi) and make more power because there is less restriction in the system.
Restrictions are from air filter to tailpipe, I actually had to teach this to an engineer on a 4"x6" high head trash pump today, because even though his chart say X rpm means X flow, reality is detached from theory when there is a suction restriction.
I have a good feeling about being able to prove the pick up in power. Known tune, known track time, one variable changed.
I will wait to install my Viking rear coilovers even to see!
I will wait to install my Viking rear coilovers even to see!
You should run it without the coilovers to actual know what made the difference. Put the 9.96 tune in and see what a pass does.
Yes, I understand that. Along the same lines, I pointed out in another thread how much fuel was consumed at the same boost level with the larger turbo. It's showing a function of turbo efficiency.
I agree with Chris that I don't believe that 20 psi is a restriction on the turbo - yet. Where will that occur? Not sure, but the race cover will make it less restrictive. He definitely hasn't hit a restriction yet. It's a bummer to work around a restriction - ask me how I know haha.
Regarding Mike's comment, until any of us hit the/a restriction just keep turning it up, then figure out what the restriction is once you have one. I meant nothing condescending about Mike's comment, but rather trying to point out that none of the increments are important in our application imo - repeat 'in my opinion'.
I agree with Duke on this and I agree with you. It would be great to just bolt on the cover and make another hit and see how it goes (hopefully track prep is good), but damn, the coil overs should help but might be the cause of a couple of wasted passes to get them dialed in.
I say this as passes here are at a premium. Between track schedules, rain outs and my schedule I'm still waiting for some prep'd track passes - I'm coming for ya' kid. I want to get close to your current PB, but I think you might lower it some 😉 (And I hope you do!!)
Boost pressure is just a number, you are right, What matters is the time and MPH with a better combo. I may have interpreted Sask Yoda incorrectly also, he may have been trying to make another point.
I think Chris will make little more than hot air at 28psi with his combo, cam is a little small and he could probably make some efficiency improvements with an intake swap, maybe bigger Intercooler down the line or increase hotside flow capacity. It's time for more sensors and data.
Yes and yes on all accounts. PSI is meaningless without supporting data; but, yes you can keep cranking it up until cranking it up stops working.
The problem is you won't know why.
Did you run out of air flow through the turbine or the compressor or the engine or all three?
Simply put you can write a maths equation (using EQ Ratio) to determine the amount of air flow and then chart it to see what it is flowing. You can build a compressor map of sorts if you wanted to. Obviously adding a other sensors like back pressure, pre- and post- transducers in the cold side, and so on will give you can idea of where your efficiency is tapering off. And most likely why.
Then you can change components strategically, not anecdotally. Then see how the engine responds. It's not a criticism, just an observation.
Did my turbo 5.3/4.8 need a 4" downpipe or a 2.5" hot side or ported turbo housings and heads or a specific supporting cam shaft or a TBSS breadbox intake to make 600hp? No. But, it is best practices to not have these things impede progress as a restriction from the outset. It's also why I left the intercooler off.
J/K. This is an amazing build... leaps and bounds beyond my current level of commitment (or focus).
Saskatchewan Yoda. FFS, that is hilarious. I am getting that on a t-shirt.
The problem is you won't know why.
Did you run out of air flow through the turbine or the compressor or the engine or all three?
Simply put you can write a maths equation (using EQ Ratio) to determine the amount of air flow and then chart it to see what it is flowing. You can build a compressor map of sorts if you wanted to. Obviously adding a other sensors like back pressure, pre- and post- transducers in the cold side, and so on will give you can idea of where your efficiency is tapering off. And most likely why.
Then you can change components strategically, not anecdotally. Then see how the engine responds. It's not a criticism, just an observation.
Did my turbo 5.3/4.8 need a 4" downpipe or a 2.5" hot side or ported turbo housings and heads or a specific supporting cam shaft or a TBSS breadbox intake to make 600hp? No. But, it is best practices to not have these things impede progress as a restriction from the outset. It's also why I left the intercooler off.
J/K. This is an amazing build... leaps and bounds beyond my current level of commitment (or focus).
Saskatchewan Yoda. FFS, that is hilarious. I am getting that on a t-shirt.
motorheadmike I agree that this is great info to help you choose parts. But I've found alot of guys get too tangled up in how to spec the build to the point that it grinds the build to a halt. If we were talking about 600-900hp NA builds, then I'm with you, but the turbo makes for an easily resolved situation - just add a little more boost to overcome a design issue.
And finding the restriction isn't near as hard as it used to be with bunches of sensor inputs to monitor.
Chris, how much timing at 20 psi on the 9.6 pass?
And finding the restriction isn't near as hard as it used to be with bunches of sensor inputs to monitor.
Chris, how much timing at 20 psi on the 9.6 pass?
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