Sweden964Cup

hey everyone!

Does enyone have some Info or experience about the Thottle body 71mm Sport replacement from FVD?

http://www.fvd.de/de/en/Porsche-0/96...9-%D871mm.html

is it just too mount it on the original throttle body?? or is 71mm too big?

Best regards!

Fly911

I'm planning to buy one, one of these days. The 71mm will give you approximately 5% bigger cross section area compared to the 68mm original one, and in theory 5% more air in to the engine. If you can match the fuel to the increased air, you should (again, in theory...) get 5% more power.
If you combine this with a new DME chip from FVD, and get an exhaust system that can get rid of the increased exhaust gasses, then the total increase may be as much as 10-15%
Call FVD and talk to ***** Brombacher, and he can tailor make a chip to your liking...

Sweden964Cup

thx for the apply!

yes i hope too get some power out of it, setup is
71mm throttle
catbypass pipe
Kn airbox
Custom made Chip.

aiming for 300+ i hope.

//SwedenCup

NineMeister

Interesting.

The mounting hole in the plastic cross pipe is 70mm diameter.

Sweden964Cup

yes that is what i wonder also, how shall that work...

frankvan

When i hear of things like this i think back to my youth when i had a 2 liter toyota racing engine with side draft carbs. Each barrel (there were four) was 40mm. I tried an "upgrade" to 45mm and failed. The engine wouldn't idle below 1200 rpm, the power didn't come on til 6000 rpm (the noise it made up there was intoxicating), and, unfortunately, the engine experienced valve float at about 7000 rpm....talk about a narrow power band!
Bigger is not necesarily better.
OTOH, 68 -> 71 is a lot smaller jump than 40 -> 45.

GT TWO

Mine has a throttle body upgrade which JZ Machtech did along with cams and some head work.

I will dig out the paperwork as it has a part number on it.

Im sure the 993 has a larger throttle body?

Sweden964Cup

im not sure they do acually they got the same replacement for the 993 at FVD also

//swedencup

NineMeister

964 (91-94) and 993nVR have different throttle bodies but both are 68mm bore. Intake manifold is same on both at 70mm.

NineMeister

Years ago I tested a 70mm throttle body on a 964RS which had our first ever 9m Motec +1 conversion. From memory the engine made around 348hp with the stock TB & 351hp with the 70mm on our dyno, i.e. around 1% more. In all truth, much more noticeable than the slight top end hp increase was the faster engine response on the road with the larger TB, due entirely to the relative increase in open area for any given throttle angle change. My prediction from this is that anyone fitting a 70mm TB will "feel" that the engine is more powerful, whereas in fact it is simply getting more open area for any given throttle position - thus quickening the response.

A few years down the line I revisited the whole 964RS intake system / throttle body sizing conundrum whilst working on another 9m Motec +1 conversion, and after many, many tests concluded that the flow through the TB (read performance) was completely limited by the shape and turn of the intake rubber elbow; by substituting this for a large radius bend I managed to find another 4-5hp and equalised the performance with either the 68mm or 70mm throttle body. At the time I considered making a custom carbon intake pipe to replace the stock elbow, however further tests showed that we could achieve similar results with a longer intake pipe which stabilises the flow after the filter & builds up more velocity in the tract before the elbow. With the revised long pipe design we found 3hp & reduced the difference between stock & 70mm TB to around 1hp.

The photos below are of a Motec equipped 964RS CS on the dyno, rear bumper removed for ease of access whilst exhaust testing.

ThomasC2

And then the big quesition. Is it possible to buy that pipe as a separate piece?

Thomas

evoderby

Hi Colin,

Thanks for your indepth contribution to this thread. Very much reminds me of a David Vizard quote: "I don't have opinions....just a flow bench and a dyno".

One question arises:

<<completely limited by the shape and turn of the intake rubber elbow; by substituting this for a large radius bend I managed to find another 4-5hp and equalised the performance with either the 68mm or 70mm throttle body. At the time I considered making a custom carbon intake pipe to replace the stock elbow, however further tests showed that we could achieve similar results with a longer intake pipe which stabilises the flow after the filter & builds up more velocity in the tract before the elbow. With the revised long pipe design we found 3hp & reduced the difference between stock & 70mm TB to around 1hp.>>

What would have been the outcome of combining the two e.g. elbow + intake pipe? ;-)

Cheers,

Harald

evoderby

Hi Thomas, the nice thing about the motec fitted to the car in Colin's pictures is that it does away with the airflow metering device altogether.....whereas bosh equipped cars won't run with the intake pipe fitted directly to the throttle.

ThomasC2

I was thinking about connecting it to a "993" MAF which is round as the pipe.

Thomas

GT TWO

Interesting stuff.

Mine has upgraded TB, cams, head work and a chip and I have several dyno prints for 290ish bhp 265 at wheels.

I will have something built next year, probably a 4.0 on throttle bodies as I just can't help myself