dove

0.3 is quite significant over 0-60 times,are you really so sure that its down to the cone? 1/3 of a second can be gained or lost due to driving,how did you manage to record this so accurately?
Paul
C2 cab

rutz964C4

Hi Joey

What´s the weight you entered on the G-Tech? I am planning to do the tests also with mine.

Another question what´s the max G you got on acceleration?

Thanks

ALEX

Ruairidh

HI Joey, where did you get your EVO cone filter from?

I'm going to try that with my cup pipe.

Although from all I'm seeing I think I made a mistake by going the cup pipe - primary bypass route rather than the secondary bypass route - torque is more important to me than top end speed. Ah well!

Nice post by the way - I appreciate your setting out the data like you do for your mods and tests, very helpful.

joey bagadonuts

Yes, Paul, I know it's significant. That's why I keep pushing the silly thing.

In terms of accuracy, if you had read my link (hint, hint) you would've known that the numbers reflected an average of three "acceptable" runs. Yes, you can get numbers all over the map if you screw up the launch, so I tossed out the bad runs. I felt that only the ones I "nailed" should be used in the averages. Not the most precise measurement, but I think my methodology was sound.

Alex, I didn't enter a weight because it is not necessary for the 0-60 measurements--just a level surface. Weight is for hp and other values which I did not measure (but I understand from the Tech running the dyno machine that the G-Tech hp numbers are pretty accurate, as well).

Ruairidh, I got the EVO filter from EVO Motorsports directly. That seems to be the best price ... by far!

914und993

Sounds like Joey B was pretty meticulous about trying to achieve consistency, but the launch is still a highly variable part of his data.

Precision would be improved by measuring the time it takes to get from say 3000 rpm to 6700 rpm while staying in 2nd (or better 3rd) gear. That would take the launch out of it, though the numbers might not seem so useful as a 0-60 time.

With the newer G-tech Competition, even in a 0-60 run you could get peak torque and horsepower numbers to compare independent of the launch.

Dropping 0.3 seconds from a 0-60 time in the 964 would require roughly a 20 hp improvement to achieve, and I really doubt that changing the airbox would do that. I think Porsche would have figured that one out on their own.

Chip

dove

My list of mods are;
Cat -bypass
G-pipe
Chip
KN filter or maybe cone filter(at the price its worth a try)
But my question is,is it really worth me doing the secondary bypass?

Paul
C2 cab

joey bagadonuts

Chip, While I agree with your logic, I think we're talking about two different applications: street and racing. The design of the street airbox needs to address noise suppression, wet weather protection as well as performance requirements. When Porsche puts together a race car, however, they ditch the big box and install a BMC or K&N cone filter, right? So I'd say Porsche DID figure out that cone filters are the performance choice, but yes, the 20hp gain would be a stretch.

914und993

I don't discount the likelihood that there are some gains to be made at the 964 airbox. I don't know exactly how NA 964 race cars came from Porsche, myself - maybe someone else does? I suspect there are other changes in the race cars too, like dispensing with the flapper air metering system and the like that might make fitting the street production airbox cumbersome. I guess I'm just being the Devil's advocate .

Too, Porsche increased the air filter area on the 993 by about 50%. That might have been because of a realization that the 964 filter was a tad bit restrictive, or maybe because they started ventilating clutch air flow into the air filter box and needed more particle holding capacity.

Where are those Porsche design engineers when you need to ask them a good question or two? Wouldn't it be great if Porsche kept an updated online FAQ on all their cars to answer questions like this?

Chip

pzull

Changing to a cone filter might have gains elsewhere but not because it has a larger diameter pipe than the rectangular connection point of the stock airbox (see diagram in earlier posts. The rectangular shaped restriction will still be there because that's the shape of the intake where the flapper is, so having a bigger pipe between the cone and the flapper doesn't do anything to alleviate the restriction. Maybe flow is better since its a smooth pipe and not a "turbulence box".

Just got my GruppeM airbox with cone (like more like a pyramid) filter inbuilt. Hope to get 5hp out of it from cooler air it sucks in - the larger nozzle goes all the way up to the rear spoiler grill so less hot engine air gets in

joey bagadonuts

Yes, pzull and Chip, there's probably more to the gain than just the airbox or flange design. Even though I saw a dramatic drop in 0-60 times when switching filters, it was probably because I found a good combination of chip/intake/exhaust as opposed to a single element which caused the big drop.

David K.

The important thing to look at on this chart is the shape of the torque curve do to the S-Car-Go headers. It broaden up the torque curve a lot. Also note at the time of this dyno run the valve guides were on there last legs.

pzull

I just did a air/fuel mix test on my car on the road since there aren't any AWD dynos near me.

I got pretty much the same result as Joey except for the kink.

At WOT going from 2000rpm to redline in 2nd & 3rd gear.

The mix was steady at 13.9-14 right up to near 4,500rpm then it dipped down to between 12-13 from 4500 to redline.

However at partial throttle acceleration even below 4500rpm, there was some slight enriching of the mix to about 13.5

It seems strange not to have enrichment of fuel mix for hard acceleration even below 4500rpm for any car. Was this done because of emissions regulations???
I figure if there was higher enrichment, I could run with more ignition advance and get some extra power/torque in the below 4500rpm range. Is optimum ignition advance for power set at just below pinging level?

Any views?

914und993

Maximum power, apart from spark advance issues, comes around an A/F ratio of 12.5/1, although the power vs. A/F ratio curve is pretty flat in this zone, so you don't have to be spot on.

I think the reason the car doesn't alway run in the 12.5/1 A/F ratio zone is indeed due to fuel economy and emissions considerations.

Chip

pzull

Thanks chip.
What about advance? Do I just tune it to pinging then back off a little over the entire rpm range and load?

BTW, how does a stock 964 engine management detect load? As far as I know it only have that airflow meter flap and rpm readings. no throttle position or manifold pressure

914und993

I'm afraid I know little about tuning a 964. Adrian could tell you more about how the 964 DME decides on fuel flow and ignition timing.

How are you adjusting ignition timing? You must have a special DME to pull that off, I think.

Chip