Mike Roblin

I’ve got the larger GT3 throttle body and IPD plenum, can software tuning gain me much more? If so what tuner does everyone recommend.

I have access to 93 octane FWIW.

hardtailer

Not really IMHO. Just buy a more powerful 996.
Unless it's all about the journey, then I'd say go for it just don't expect any RoI.
The X51 package shows what's possible.

Mike Roblin

It’s in a boxster racecar so just wondering what might be possible. Car has no cats either so...

Mike Roblin

Any other opinions or thoughts?

theprf

If you are only ever using 100 octane you ought to be able to tune to advance the timing a little. You can always raise the rev limiter. That's about all that can be done on a NA engine, as adding fuel needs to be balanced by more air. There's little you can do to get more air so there's little point in adding more fuel. Any air additions should be within the tuning range of the DME already.
Perhaps you can adjust the variocam setpoints or delete the SAI or something like that.

sdematt

Bore out to 4.0L.

zbomb

If you really want to go nuts with your M96... which personally I would not do...

FVD sells some Schrick MFG cams for the 3.4

https://www.fvd.net/us-en/1001059960...l-schrick.html

Mike Roblin

So the DME will auto adjust when we put the larger TB and IPD plenum on the engine?

sdematt

I went with Shrick cams and went to 3.8 from 3.4. I'm a fan.

theprf

I would think so, never actually tried though. Those upgrades aren't going to change the air into the engine more than a couple percent which should be within the DME's range. This assumes you're running pre-cat O2 sensors because that's what the DME needs to do the mixture adjustments.

triggz82

Check out my post on catless xpipes. The DME does not compensate enough for the catless setup using o2 spacers IMO. I get drivability issues under heavy load at ~1500rpm. Seems to be hit or miss but I am not the only one this has happened to. You'll also lose a lot of torque in the lower range.

Granted if this is a race car, you might spend most of your time above the 4k rev range where your upgrades will be very noticeable without the need of a tune.

Mike Roblin

Thanks everyone, looks like we’ll install the GT3 TB and IPD Plenum and see what happens.

EVOMMM

Keep us informed of your progress I’m very interested in your same setup I’d like to do the same
Mike

golock911

My vote: get a dyno first, then change the TB/Plenum, dyno again, then tune, dyno a third time. We NEED data.

Actually, maybe those are dumb comments that would waste money. I recall from some discussions that tuning the 3.4 is limited due to the DME version. Stupid memory can't recall clearly. Certainly worth some searching.

3/98 911 coupe

They make some real good cams. I had some experience in my 93 vr6 corrado, emerald green. talk to them and ask them about the tune, get the hp/tq chart. If I recall correctly, for the corrado they made 264 and 268. Anyway I chose the milder cam, a friend of mine went with the 268. On 102 octane at the drag strip, I would outrun him almost by a ten, his car had a wilder idle, he was loosing too much down low. I’m just mentioning this because since you are talking about a track car with a real wild set of cams if the straightaways are short your lap times are going to suffer if you loose to much on the bottom, don’t rely on your but dyno. One cool thing is that I could keep up and sometimes beat mustang v8s. For the corrado there was a company that would basically machine off the lip on the throttle , anyway the cost was $250, I had access to a dyno, yes 5 hp gain. Is there something like that available for the cable 3.4. ???? Has anybody ever gasket match the throttle maybe doable with a dremmel. I had a boss with a Judge GTO and his daily was a SHELBY GLHS, we worked on our cars on the weekends and we did everything the old way. My daily was a euro spec Scirrocco 16v black, gold bbs rims. I’m thinking our cars (996) are 100 percent about flow, Vision told me that there is not to much to gain with head work and they also stated that the plenum on my car is a waste a money.

Bobby Labonte in Fronf of Jeff Gordon. Penny oil street nationals 13-17 second braket I finished second. Bottom 1994 pikes peak hill climb, we sponsored Roger mears. I got a ride in that car.