JKelly

On the 85 & onward cars. Is it possible?

John Speake

Why do you want to bore it ? It's the least significant restriction in the inlet path. ..........

Regards

JKelly

I was just wondering if anyone has done it and what kind of results they received.

John, Do you know how many square inches the MAF is?
Edit: Nevermind, I think it is 3.5"

John Speake

9.621 sq.ins. if my maths are correct ! It is 3.5inches effective dia.

One of the big stroker cars (was it Marcs ?) chopped up a MAF and grafted it onto a larger bore plastic pipe

Scott M.

JKelly;

Professional flow technologies (Por-flow) can make you whatever size/flow MAF you need. Hot wire or Hot film. And they can even calibrate it to any specific air volumn.

I have one on my stroked GTS that was initially designed for a big hp 911 turbo (Bosch style) but was recalibrated for the 928 flow.

Scott

sharkmeister85

Scott,
What kind of performance increase did that give you(if any)? I'm guessing their MAF is more expenive than buying a new stock one from Bosch.
Glenn

Jim bailey - 928 International

John . Mark Anderson runs the modified Mass airflow larger diameter but it is with two throttle bodies individual runner carbon fiber intake on a stroker.

John Speake

Thanks Jim, my memory gets worse.........:-)

John Struthers

JK,
Have you turned into a HP ****?
For improvement data you would probably have to dyno before and after...
And do a G-tech run (0 - 60), and we aren't talking more than 1/10 -3/10's of a second, which would equate to about the same improvement in the 1/4 mile times.
There isn't all that much to ream out there if you are thinkiing of doing just
the throat at the manifold connector boot. A more noticeable, but still much
less than a second improvement would be a ream and flappy -aka buttrfly valve, sort of) valve.
But you will obviously have to woo a precision machineist $$$$$$$ !
We could argue all day about calibration particularly if you aren't employing the kickdown switch.
But with kickdown engaged how much the heads flow(cfm) and I don't know of any production factory head flowing at over 95% efficency -and that's a stretch- .
So even a small incremental increase in cross section can't hurt.
And hungry combustion chambers as a rule will take all they can get within the limits of design.
I'm not sure at what point your mapping run full rich under normal high speed running but
when the kick down switch is engaged you should be at full rich anyhow.
Maybe Murph could give you the skinny on lean conditions at 5, 7, or better psi of boost for your engine type. I don't think he had to mess with anything (fuel air mix).
Could be wrong here but I think I read in his posts' somewhere that there was no problem
up to 7 -8 psi of boost.
Headers would be a better run for your money giving you more low end grunt -and faster low end grunt- your mid range would still be strong but you lose a little on top end.
Speaking of which...
How many of us really air out our sHARKs at the outrageous end of the speedometer more than a few times a year? Most of our knife fighting is at speeds less than 90mph and we are generally rolling at 40 -60mph when the beast overcomes common sense.
Pattycakes and her elderly, low HP 4.5L engine with 3spd auto still scoots around pretty good but nothing like that beautiful white of yours ( sniff, boo-hoo).
I have to be alert, drop to second gear and be at 3500 -4200 rpm when lesser car owners pull alongside with visons of telling their friends that they blew away a Porsche 928.
By and large they have to lie...
With gas prices what they are today and me cruising at say 3800 or better rpms my mileage is suffering and I don't feast on as many Camaro's, Stangs', ect. like I used to.
If you are determined to have some extra HP on demand but don't need it all that often see if anyone has a nitrous set-up in the 50 to 80 HP range. They can tell you if there is a tragic downside to using NOX.