V2Rocket

how big can you go with regards to the inside size of the plenum?

a 4.6L mustang before 2005 has a 65mm throttle stock with a 4-bolt square flange. as someone suggested you could just cut off the original and weld on a new one. should be able to pick one up for pennies at a boneyard...be creative to get the TPS working.



http://www.ebay.com/itm/Throttle-Bod...428800&vxp=mtr

Thom

The Audi TB needs to be rewelded on one side to reproduce the "square" bolt offset of the stock TB. I attached it on the inlet plenum by tightening the bolts from the inside of the plenum. It works 1 to 1 with the stock TPS. Might be a PITA to proceed the same way on a stock intake, but I see little point using a larger TB on the stock intake anyway.

Tom M'Guinn

Thanks Thom. This would not be for the stock intake --and my SFR intake is drilled for a 928 TB --so bolt pattern will need to be adjusted either way. Happen to have any pics and/or more details on exactly what motor you took that TB from?

refresh951

Thanks Spenser. I just went ahead and purchased one of these. This unit looks promising and at $29 it is worth having it to see if I can make it work. Thanks again. I will post up what I find.

refresh951

Tonight I used my Arduino logger to measure pressure drop across the TB. At 1 Bar the minimum pressure drop through the TB at WOT was 1.3 psi. No doubt at mid to high power levels the stock TB is a restriction.

hacker-pschorr

Larger throttle body, interesting topic.

The most powerful road going 928 in history uses a stock 928 throttle body:

https://rennlist.com/forums/928-foru...deo-added.html

The owner is a good local friend of mine. He did a lot of testing and found the smaller 928 throttle body (compared to larger aftermarket units) was preferred to keep air velocity higher versus overall volume from a larger unit.

He also liked the pedal to throttle plate ratio build into the stock Porsche unit.

V2Rocket

Could that be due to his giant plenum and short runners, versus the 951 using a longer-tapered-runner small plenum intake?

hacker-pschorr

Could be, just thought it might be an interesting data point so share.

refresh951

The 4.6L mustang before 2005 65mm throttle body does indeed looks to be a nice cheap option. I picked one up on Ebay for $29 shipped. I think Spencer suggested looking at it (thanks man!). These TB's are available in abundance. Worked on adapting it this weekend. Not bad and I was able to make a fairly simple adapter plate so I can use the 951 TPS. The flange has just enough room to drill the factory intake pattern. Even the 951 throttle cable fits perfectly with no modification. I plan on testing it later this week.

Voith

Not exactly small TB

Tom M'Guinn

Shawn, thanks for the update. If you get a chance, would you mind measuring the spacing of the original mounting holes on the throttle body? I'd be putting it on an aftermarket/SFR manifold (set up for a 928 TB), so curious how close it would be.

How is the throttle cable pull range compared to stock -- think it will create the same pedal travel length as stock?

Are you planning to pressure test it -- I'm always a little leery of n/a throttle bodies being able to contain 20psi without blowing out like a popped balloon...

refresh951

Tom,

Hole spacing on the Mustang TB is 3" x 2.6"

Pedal travel will be less as the MTB has a 0.6" radius vs 0.9" on the 951. I will see how it feels later this week.

I will pressure test it for sure. I am also curious about the idle air screw.

Tom M'Guinn

Wonder if you could tack the Porsche cam onto the ford TB? (Or is it aluminum v. steel?)

refresh951

Yes, aluminum and steel but should be able to screw it together. Not a bad idea, I will look at it tomorrow.

V2Rocket