maf and throttle body diameter

[jaykay]

I see a lot of engine conversion intake plumbing with sharp 90s into the throttle body. I personally will try to avoid this with the largest radius 90 out the throttle body I can find and then a 30 deg to correct for the angle away from the intake side.....currently I am eye balling it and have not measured the engine intake diverter tee angle.

Interestly I have noted pitting on the inside of my low time cayman tb, coincident with the outside radius bend of the cayman diverter tee and intake path. This gives me the feeling that presenting the air flow straight through the tb may have some value; less turbulence

[shalco]

Thanks for that, I hadn't considered the problem of the tighter inside radius on the curved plenum.

My car is an older 2.5 so was a cable throttle. I can confirm upgrading to a cable 996 3.4 TB is a big increase in power. I think this starts at 76mm & tapers down to maybe 74mm-ish at the butterfly.

I do have a previously fitted cable 80mm TB. This was an aftermarket ebay Nissan GTR TB. Its a good fit just needed oversized mounting holes, & an adapted bmw iacv plumbed in to the aos take off. It did from memory lack some torque below 4000 rpm compared to the 3.4 TB.

I think I may revisit this set up as I think its a shorter length compared to the 3.4 which means a less angled pipe could be connected.

[Stiletto Pat]

Gotta Bump this up - looking for the latest from you intake enthusiasts!