Can this be true and/or Safe?
Originally Posted by 03BREvo8
that 24-25 psi.. just pump gas right.. with alky its more like 27-28
Originally Posted by Ted B
One can run as much boost as he likes (e.g. 30 psi spikes) with the stock injectors, so long as the hp level at that point does not exceed the injectors' max flow rate.
you are correct sir.. i have hit 29 twice, when the hose blew off... damn rvm i/c pipes...
Originally Posted by Jorge T
Actually it is a boost line, not vacuum and if you disconnect it your turbo will overboost.
When EBCs are turned off it maintains the solenoid shut and directs all boost to open the wastegate.
When EBCs are turned off it maintains the solenoid shut and directs all boost to open the wastegate.
Originally Posted by SuperHatch
You are correct in saying that the cylinders are filled via boost pressure and not vacuum created by a downward traveling piston. However, the boost pressure measured at the intake manifold is the pressurized air that wasn't able to get into the cylinders. An engine with higher VE can flow more air at a lower boost pressure than an engine with low VE at high boost pressures. Assuming that the dynamic pressure at BDC before compression is the same as the reference pressure measured at the intake manifold can be and often times is a bad assumption...
- Steve
- Steve
The comment about increased VE at lower boost pressures seems to be true with NA engines more than a forced induction engine. Especially one with identical air flow capabilties. Meaning same cams and port work etc.
Dynamic pressure will vary with many things including static compression, load, rpm, boost pressure, cam profile, stroke etc.
For the most part I agree with your post.
Evolving Member
Joined: Mar 2005
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From: Baton Rouge, LA
Originally Posted by Precision Dyno
No it has not been only for testing. The stock turbo has been holding up very well up to now.
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Joined: Sep 2004
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From: Las Cruces, NM
Originally Posted by Precision Dyno
Charlie brown,
An engine doesn't breathe air in. Especially under boost. It is pressurized regardless of boost pressure or atmospheric pressure.
If the air was to "back up" then you would see a restriction somewhere. If there were a restriction then the turbo may continue to boost 30 psi at redline or close to it. As an engines rpm increases the amount of air being processed decreases after peak torque. That would definately decrease the life of the little turbo.
You are right that the turbo will push a certain amount of CFM, BUT what does cubic feet per minute have to with compressor efficiency?
Timing is timing. There is an ideal figure for every load and rpm. It doesnt matter if it is "retarded" or advanced. It is a figure that is calculated to provide the most amount of power without sacrificing reliability in the quality of fuel being used. Advanced timing does NOT give you more power. The proper timing lead (whatever number that may be) along with the proper parts of air and fuel do.
An engine doesn't breathe air in. Especially under boost. It is pressurized regardless of boost pressure or atmospheric pressure.
If the air was to "back up" then you would see a restriction somewhere. If there were a restriction then the turbo may continue to boost 30 psi at redline or close to it. As an engines rpm increases the amount of air being processed decreases after peak torque. That would definately decrease the life of the little turbo.
You are right that the turbo will push a certain amount of CFM, BUT what does cubic feet per minute have to with compressor efficiency?
Timing is timing. There is an ideal figure for every load and rpm. It doesnt matter if it is "retarded" or advanced. It is a figure that is calculated to provide the most amount of power without sacrificing reliability in the quality of fuel being used. Advanced timing does NOT give you more power. The proper timing lead (whatever number that may be) along with the proper parts of air and fuel do.
An engine does breathe air. under boost it may be getting force fed but nevertheless air is waiting for the intake cycle to happen. the faster and more often the intake valves open---- the less air you have pressurized waiting in the intake manifold.
i'm not worried about compressor efficiency more so about air efficiency . if you are allowed only 500 CFM of air no more, no less, it is better to get it at a cool 21-23 psi rather than a hotter 30 psi. And one way to get that pressure up to 30 psi is to make the engine accelerate less quicky. And one way to to that is by having ignition timing retarded far less than would be ideal either by tuning or by knock sensor correction
Last edited by Charliebrown; May 19, 2005 at 03:41 AM.
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