Pressure drop over the carb?
Turbo Mini Forums

Hi,

has anyone ever measured boost before (Plenum) and after (manifold) the carb simultaneously? How high is the pressure drop over the carb?
Harry

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

I'm sure it was 1.5psi when i measured it. VERY long time ago though...

ahh, now then - I answered this on the lines of pressure drop across the restrictor in the plenum...



If we're talking carb&plenum, that's a different matter.

Clearly - if we take an bog-standard metro turbo engine at 6000rpm, and MW's 20+psi 200+ hp motor at 7000rpm, we're going to see a different pressure drop. That is something i haven't measured....

Edited by turbodave16v on 1st Nov, 2005.

I measured 1.5 as well on a std ish engine...

You will get a pressure drop and IIRC you need it to make the carb "density" sensivity.

AlexF

Were you refferring to a pressure drop across the whole thing - like the problem the R5GT guys have with their smallest of small carbs?

Yes, across the whole thing! Manifold vias plenum!
Hehe - funny that you are talking about the R5 carb; on a local drag event the R5 GTTurbo guys were very interested in the Turbo HIF44 carb.

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

If i had 4 inlet ports i wouldn't be on a carb - i'd be playing with megasquirt!!!

My Megasuirt is already orderd! Measured about 0,25bar boost loss today on the dyno at 1,3bar in the plenum.

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

Interesting - wide open throttle i assume?

so 19psi measured in the plenum, and a drop of 3.6psi across the restrictor / carb, gave 15.4psi in the inlet?

Yes, numbers are right; mesaured at WOT! Will connect my 2nd MAP Sensor to the plenum next time - so I havn't to compare a MAP against a (calibrated!) analog onboard instrument.
Where do you take your boost signal?

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm