When upgrading my manifolds i seen 2 PSI drop in Boost with each the exhaust and Intake manifolds . To me this was completely awesome now i can keep my foot in to it for longer than before.

I also dropped from a 60 psi boost gauge to a 35 psi , i have had 50+ on my truck , with the rebomb i wanted to run around 35 max , im sitting at about 42 WOT but when the boost gauge pegs i feather the throttle to keep the needle bouncing pegged instead for being laid down

So anyway , You dont want high boost numbers you want a mass amount of cold free flowing air .

I think a boost gauge is not the proper way to measure / regulate the turbos efficiency and i think some sort of Mass Air Flow Sensor would be a better interpretation of whats exactly going on

What do you think?

 

very interesting question. if some one was smart enough, they could rig one up, but if it was a better way of seeing the performance of it, would not have someone figured thhis out before? to see the actual volume of what it is pushing, i think would be very hard to rig up, and would be restrictive in airflow. but who knows, u might be on to something

 

Boost is simply a measure of resistance, MAF would let you know how much actual air is getting into the engine. I wonder if a MAF sensor would work under boost though...

 

MAF do BUT the volume would have to be calculated with a BAP (barometric air pressure) instead of a MAP (manifold absolute pressure sensor) in combination to the MAF but that being said GM has used 3 and 4 bar MAP sensors in Forced Induction applications.

most gas engine guys that go forced induction end up going speed density (no air metering)

In my uneducated opinion these diesel motors (i am talking about the 12v cummins right now) are so basic in the way they operate that unless you are over fueled there is no way that the turbo will make more than 35# of boost.

alot of times you have to get more boost, PSI (my simple mind reads this as more volume per square inch since the psi is increased) to get a clean burn. if you have too much fuel then high boost is needed if you don't have adequate air flow at a lower boost pressure.

that being said to get good flow at a low PSI range you need a smaller turbo like the stock 57mm or so area. this makes the turbo perform in it's efficiency range. to get good flow in high boost situations then you need a huge turbo like an S400 variant. to make an s400 work well you need HUGE fuel.

this is when tuned twins are great and show the best of both worlds, small and big chargers and having tons of fuel and great streetability.....

now i'll crawl back under my rock and see who else thinks the way i do......


true Bobby but remember this, if you have a turbo that moves (i'm pulling numbers out of my a$$) 450CFM at 30PSI then the same turbo might flow 500CFM at 40psi..... but you buy a turbo that flows 650CFM at 30PSI and 750cfm at 40psi.... it is more of a measure of resistance in relation to the volume being pushed through the intake. that being said the first turbo at 30psi might perform the same as the second turbo at say 15psi......

someone please correct me if my logic is incorrect....

 

I agree with your thoughts , And i will add that 60 PSI can be obtained under completely different conditions .

1 super heated compressed air - BAD
2 Cold Fast moving air -Good

I guess you have to look at where exactly the restriction is .

anyone could plug off there exhaust and get 60 PSI , with that being so to me Boost numbers don't mean anything in determining turbo efficiency.

We need to measure intake air temperature and air flow CFM , not Pressure !

I would love to see some numbers from the HY35 and HX35 compared to the S300 , having a boost gauge means nothing in this comparison

we block our wastegates all the time on stock turbos to gain a few PSI , but is it good PSI or is it just unneeded pressure

 

bumpage

 

Here are my thoughts;

One must recognize that boost is nothing more than pressure and high pressure for extended periods is generally bad news.

So, one should really be looking at boost gain or loss across a selection of equipment. In otherwords, put a gauge between the turbos (on a twin set) put a gauge between that and the IC, another one after the IC and another one after the intake manifold. See what I'm getting at?

 

you are right chad. volume