airflow meter size
Discussion
gents ( and any interested ladies )
I've just measured the opening on my griff's airflow meter and I have to say its a bit on the small side....
As its only Ø55.0mm it will definitely be holding things back a bit, whats the size of the jaguar / 5ltr 5AM one?
Or does anyone have any pressure drop figures?
Its a bit daft when you consider how much attention is paid to fitting bigger throttles and trumpets on the old rover when its got to draw all its air through this hole....
as as case in point 68mm is the std throttle size and its recommended going up to at least Ø71mm for high powered engines...
Matt
I've just measured the opening on my griff's airflow meter and I have to say its a bit on the small side....
As its only Ø55.0mm it will definitely be holding things back a bit, whats the size of the jaguar / 5ltr 5AM one?
Or does anyone have any pressure drop figures?
Its a bit daft when you consider how much attention is paid to fitting bigger throttles and trumpets on the old rover when its got to draw all its air through this hole....
as as case in point 68mm is the std throttle size and its recommended going up to at least Ø71mm for high powered engines...
Matt
350matt said:
gents ( and any interested ladies )
I've just measured the opening on my griff's airflow meter and I have to say its a bit on the small side....
As its only Ø55.0mm it will definitely be holding things back a bit, whats the size of the jaguar / 5ltr 5AM one?
Or does anyone have any pressure drop figures?
Its a bit daft when you consider how much attention is paid to fitting bigger throttles and trumpets on the old rover when its got to draw all its air through this hole....
as as case in point 68mm is the std throttle size and its recommended going up to at least Ø71mm for high powered engines...
Matt
I've just measured the opening on my griff's airflow meter and I have to say its a bit on the small side....
As its only Ø55.0mm it will definitely be holding things back a bit, whats the size of the jaguar / 5ltr 5AM one?
Or does anyone have any pressure drop figures?
Its a bit daft when you consider how much attention is paid to fitting bigger throttles and trumpets on the old rover when its got to draw all its air through this hole....
as as case in point 68mm is the std throttle size and its recommended going up to at least Ø71mm for high powered engines...
Matt
I think the 3AM is the same size as the 5AM meter. if thats the question your asking? I know Mark Adams did/does do remaps on the lucas ECU with another JAG AFM (20AM I think?). but from what I do remember he would only recommend this on high output 5 ltr cars, as it not the limiting factor.. not sure what your car is??
maybe if you have all other breathing mods then its worth doing if not its an expensive ball ache for very little gain. If your already going new ECU route then great go for it as you can choose what you want, even ditch it altogether and go MAP as I think dnb suggests..
(as you can see from the number of I thinks in my post I'm no expert
)350matt said:
gents ( and any interested ladies )
I've just measured the opening on my griff's airflow meter and I have to say its a bit on the small side....
As its only Ø55.0mm it will definitely be holding things back a bit, whats the size of the jaguar / 5ltr 5AM one?
Or does anyone have any pressure drop figures?
Its a bit daft when you consider how much attention is paid to fitting bigger throttles and trumpets on the old rover when its got to draw all its air through this hole....
as as case in point 68mm is the std throttle size and its recommended going up to at least Ø71mm for high powered engines...
Matt
I've just measured the opening on my griff's airflow meter and I have to say its a bit on the small side....
As its only Ø55.0mm it will definitely be holding things back a bit, whats the size of the jaguar / 5ltr 5AM one?
Or does anyone have any pressure drop figures?
Its a bit daft when you consider how much attention is paid to fitting bigger throttles and trumpets on the old rover when its got to draw all its air through this hole....
as as case in point 68mm is the std throttle size and its recommended going up to at least Ø71mm for high powered engines...
Matt
Matt - I've had the Mark Adams supllied 'BIg Bosch' fitted to mine.
picture stolen from the RPI website for comparision..
You are right - if it's smaller than the throttle (68mm) .. mines 73mm .. then it's a restriction.
I'll measure the size of mine tonight..
spend said:
Is the "BigBosch" (nice name ~ like it) much less restrictive? That blinking great bar thru the middle looks to overcome any increase in diameter???
Dave
Dave
My thinking too..
I'm going to check it out tonight..
I suspent that having a restriction actually helps low speed power .. same as a venturi does in a Carb but at higher rpm and power causes a power drop..
So overall - the net effect is not as bad as you might not think.
trackcar said:
Hi Peter, did you ever get to the bottom of your ECU gremlins in the end?
It's been shelved for a while due to lack of time and money but I've started on it again a little while ago. Suffering from 'feature creep' a bit though. I'm secretly hoping that the MS router board will be out by the time I'm ready to get it up and running.
Well I've checked out my Big Bosch..
It's a 80mm (although actual measurement is 76mm internal)
>PBT - GF30< (serial 0280 218 010) .. something like is seem to be fitted to modern Alfa's..
Bore is 76MM - restriction (hotwire pack is 53mm * 12mm)- looks slightly different to the earlier picture (larger too).
Cross sectional area 4536 sq mm - 636 sq mm for the restriction
works out to 3900 sq mm.
A 68 mm inlet throttle is 3631 sq mm..
and the 55 mm Air flow meter is 3631 sq mm..
So - this new one would offer 'no' restriction to someone using a 68 mm throttle..
Matt - when did you swap from the Cerbera to a Griff ?
It's a 80mm (although actual measurement is 76mm internal)
>PBT - GF30< (serial 0280 218 010) .. something like is seem to be fitted to modern Alfa's..
Bore is 76MM - restriction (hotwire pack is 53mm * 12mm)- looks slightly different to the earlier picture (larger too).
Cross sectional area 4536 sq mm - 636 sq mm for the restriction
works out to 3900 sq mm.
A 68 mm inlet throttle is 3631 sq mm..
and the 55 mm Air flow meter is 3631 sq mm..
So - this new one would offer 'no' restriction to someone using a 68 mm throttle..
Matt - when did you swap from the Cerbera to a Griff ?
Edited by rev-erend on Tuesday 13th March 21:52
Roberto Rica said:
Hi Jools
When you say 'restrictive above 150bhp' do you mean that the power/torque curves show a distinct change in gradient/shape once 150bhp is reached? Perhaps you could put up some power curves as evidence of this phenomenon.
Thanks.
Rob
When you say 'restrictive above 150bhp' do you mean that the power/torque curves show a distinct change in gradient/shape once 150bhp is reached? Perhaps you could put up some power curves as evidence of this phenomenon.
Thanks.
Rob
got no graphs to hand, but essentially "yes", what you're saying is exactly what happens
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