I was wondering if anyone knew if a 964 throttle body rebore process (machining) will increase the air flow capacity, and increase throttle response (as it does on many cars)? Apparently, it depends first on whether or not the throttle body CAN be rebored - meaning, is their space to machine the body out to a larger volume? And second, whether the additional volume is sufficient to improve the flow capacity.

Thanks.
Erick

 

you could definately get it bored a little bit. Never seen a 964, but I imagine it's like every other production TB where there is enough to 'grow'. If you have a cylinder hone, that will do the job. Removing the burrs from casting and polishing it will significantly improve airflow

 

Thanks Red 944,
You have further sparked my curiosity.... now I need to determine whether the cost of doing a rebore/polishing is worth the results.

I wonder what a legitimate increase in power would be for the 964? If I only gained 3hp, I wouldn't be interested.... but 10hp might be worth it! I wonder....

 

Eric,

Performance Products offers throttle body reboring. Looks pricey to me. They claim some impressive gains if you get a free flowing exhaust and a chip at the same time.

I have also seen someone on Ebay offering this service for other Porsches. What is takes to make a new throttle flap with larger diameter and hone the body. Check the link and ask the guy if he could do it to your throttle body

<a href="http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1857641549" target="_blank">Ebay: throttle body boring</a>

Hope that helps,
Ingo <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

 

Give Ed at Big Bore Throttle Bodies a call 800-792-9338, he just did mine. He was able to increase size by 3mm which is as large as the stock 951 TB can be bored and a nice brass butterfly to complete the quality job and quick turnaround.

 

Thanks for the info David!

So what did you notice after 3mm rebore?

 

I am still in the process of installing my new
2.8 and with all the mods, there will be know way to tell just what the bored TB has done. I just thought of it as one more piece of the puzzle.

 

Call S Car Go Racing in NorCal. Ideally try to speak to Rob King, the owner. They are Porsche specialist and do TB rebores as one of their mods.

I've general found them to be pretty upfront re: performance gains and less about hype.

 

Thanks David! (both of you),
I'll contact both Ed and Rob to see what they have to say.... hopefully it's something along the lines of:
"Why yes, we rebore TB's... hardly costs anything! And the improvement in horsepower is awesome!"

I'll keep my fingers crossed.
Erick

 

I just looked in the latest Performance Pproducts catelog - they charge $375 to rebuild and enlarge your TB with a 3 day turnaround.

Problem is that you'll be starting down a slippery slope from there...mass flow sensor, high performance fuel regulator, chip, etc....just ask anyone else on this board that has been bitten!!

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

 

[quote] Problem is that you'll be starting down a slippery slope from there...mass flow sensor, high performance fuel regulator, chip, etc....just ask anyone else on this board that has been bitten <hr></blockquote>


Yea, I think that slope is called a "Black Diamond" can any stick riders confirm this?


I have been on this slope since January.

 

I had mine done by Big Bore Throttle Bodies. Was very happy with the workmanship and the price was the cheapest I could find.
Dave Fracolli

 

I had Big Bore do the body on my RSA. Did a lot of other things at the same time so no quantitative results.

If you have a 951, David Floyd, you should check with Chris White at 944enhancement.com Chris can get you a much larger body than you can bore and at what may well be a much better price. How does 65mm compare to what you got after the bore?

Alan

 

Alan,

I measure 59 mm back where the shaft runs across the TB and cost was $200. 65 mm is a big mamma, I will check that out.

The stock intake manifold opening is 62 mm, I guess you would need to bore the intake to match the 65mm TB ?

 

yep