R53 JCW Boost Pressure
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I get 13 to 14psi. Taken off my Scangauge. No mods to pulleys but I have 380cc injectors. I am going to install a vacuum operated gauge moving forward. Currently looking for one with a tattle tale needle like to one in my old 930. At least with this I can see what my max boost was after the run rather than having to look at the Scangauge while under boost.
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Native Texan (08-28-2023)
#7
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You installed a Dominator cam so you boost will be lower. I differ that DT BPV will not add peak boost pressure. It only closes the bypass sooner.
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video spam
I cannot resist the opportunity of spamming this thread with the evidence of my SC has higher boost. Bone stock MCS with 15% pulley. 15 PSI boost. The boost gauge is very useful for me to review my driving if I accelerate hard enough at different part of the track.
Boost pressure alone is not a reliable indication of power output without taking into account the engine aspiration differences. Else is just apple vs orange comparison.
Boost pressure alone is not a reliable indication of power output without taking into account the engine aspiration differences. Else is just apple vs orange comparison.
#12
On the Detroit Tuned BPV, need Chad or Nick to speak up here. From what I have read on the matter is that the seal on their valve is tighter and therefore the pressurized flow is kept in the flow and not able to leak back through the backcheck.
#13
Cam lift, duration and overlap on a cam will affect manifold pressure.
If you open the intake valve further or longer you flow more volume past the valve, hence it takes more volume to achieve the same "pre-cam" manifold pressure. In simple terms the air is leaving the intake manifold before it can be pressurized.
I'm not going to get in to overlap, do a google search it's an interesting read.
If the output volume of the supercharger is linear per rpm then you will see a lower manifold pressure.
If you have a turbo, it can compensate by opening the wastegate later the boost will remain the same or be slightly less.
Just because you see a drop in manifold pressure does not mean you have lost any performance. You are actually getting more air in the cylinder giving you the ability to make more power.
If you open the intake valve further or longer you flow more volume past the valve, hence it takes more volume to achieve the same "pre-cam" manifold pressure. In simple terms the air is leaving the intake manifold before it can be pressurized.
I'm not going to get in to overlap, do a google search it's an interesting read.
If the output volume of the supercharger is linear per rpm then you will see a lower manifold pressure.
If you have a turbo, it can compensate by opening the wastegate later the boost will remain the same or be slightly less.
Just because you see a drop in manifold pressure does not mean you have lost any performance. You are actually getting more air in the cylinder giving you the ability to make more power.
#16
As the boost with a supercharger would appear to based on crank revolutions that thereby rotate the belt that spins the SC, how would a cam within the engine impact boost?
On the Detroit Tuned BPV, need Chad or Nick to speak up here. From what I have read on the matter is that the seal on their valve is tighter and therefore the pressurized flow is kept in the flow and not able to leak back through the backcheck.
On the Detroit Tuned BPV, need Chad or Nick to speak up here. From what I have read on the matter is that the seal on their valve is tighter and therefore the pressurized flow is kept in the flow and not able to leak back through the backcheck.
In all of our testing thru the years, we always see a touch more boost out of the cars. it can be UP TOO 1 psi but always more. but again we are testing it with a mechanical gauge and etc. etc. but as soon as the BPV shuts, it's building boost, the sooner it shut the more boost the system can make int he given RPM band. given small, but it will make more, and each car is different in how it reacts to any mod you add to the car.
Chad
Detroit Tuned
__________________
#17
I cannot resist the opportunity of spamming this thread with the evidence of my SC has higher boost. Bone stock MCS with 15% pulley. 15 PSI boost. The boost gauge is very useful for me to review my driving if I accelerate hard enough at different part of the track.
https://youtu.be/Zk_FoLIXutI
Boost pressure alone is not a reliable indication of power output without taking into account the engine aspiration differences. Else is just apple vs orange comparison.
https://youtu.be/Zk_FoLIXutI
Boost pressure alone is not a reliable indication of power output without taking into account the engine aspiration differences. Else is just apple vs orange comparison.
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No, I made a device out of 2.5" silicone hose, abs pipe cap and some pipe clamps. Similar to this , shoved it onto the throttle body and pressurised the system to ~20 psi. I could hear the leaks.
As for the dt bypass valve you should be able to tell by the spring tension. The stock one that came out of my car was as stiff as a spring loaded ball point pen and the dt was maybe x3 stiffer. If my valve was busted then i'm talking out of my as*.
As for the dt bypass valve you should be able to tell by the spring tension. The stock one that came out of my car was as stiff as a spring loaded ball point pen and the dt was maybe x3 stiffer. If my valve was busted then i'm talking out of my as*.
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Oldboy Speedwell (03-06-2019)
#25
The use of boost in many instances could be replaced with back-pressure as it better explains what is happening ie: more air being supplied than being used.
I have worm drive clamps on my by-pass valve connections as the euro type clamps were leaking at 5 psi. I made a similar type pressure tester.
I have worm drive clamps on my by-pass valve connections as the euro type clamps were leaking at 5 psi. I made a similar type pressure tester.