tonytaylor

I think the LWF is a good move as it definatly gives more punch out of slower corners. You're probably on the LUK flywheel so don't have the excuse of replacing it because it has failed but you're clutch must be on the way out, right?
If regulations allow I would consider a re-gearing of the tranny. With the standard 5 speed box and under 300bhp 964s just die once you shift into 4th. I'd say it was one of the biggest differences between the 993RS and 964RS. Having run against both on track before and after tranny change the advantage of closer gears 2nd/3rd/4th is clear to me.
As to the chip, I'd be very suprised if your running a standard chip at those dyno numbers and would be suprised if a re-chip would give more. However here in the UK a custom re-chip is not all that expensive so even a little more torque/power makes it worthwhile. To gain much more power you are going to need to increase the size of the injectors. Is Motec allowable?
There is a school of thought that suggests much of improvement in power by the 993 over the 964 is due to the superior headers of the former. However once you run a "cup" exhaust set-up on a 964 it would appear there is very little to be gained by changing headers. In a pure race set-up equal length headers would be superior but you need the cams etc to go with it. 9M builds 964 engines upto 400bhp NA, and they are race proven, and the headers are one of the last things on the upgrade ladder.

joey bagadonuts

Here's my plot from a dual-roller, awd dyno. I mention it only because transmission loss is supposedly different than for a single-axle machine. Probably its greatest value is for comparisions with future modifications I may carry out. Have you considered changing the ring & pinion ratio, Tom?

Tom W

Joey: Thanks for your plot. This issue has reminded me that my car does have a new ECU. The PO had problems just before I flew down to pick up the car and the diagnosis was a bad ECU. He put in a new one. I'm wondering what it is.

I have given the R&P change some thought, but that's a mod I'm a lot less familiar with (I know what it does) and I just worry about cost and benefit. R&P change is allowed in POC for prepared, I don't remember PCA rules for it. Early on, I did have my 993 re-geared to tight gears when I had a transmission failure and the tranny needed to be pulled apart (the spider gear/shaft had failed) so I'm familiar with the great benefit of closer gears (and the cost to get them). Has anyone out there changed their R&P? What did you change it to?

While it's all apart, I'm also having the stock LSD checked out to make sure it's ok. If not, I'll switch to a newer, more sturdy LSD.

Tom W

An update.

I stopped by to see the engine and transmission dropped out of the car and I talked to the guy who dynoed my car (he appears to be a dyno geek). We looked at the data and it really is 244 rwhp. I guess I just have one of the cars that pulls hard. They are interested in the benefit for each of the mods so they will dyno again with the LFW but before the headers or chip (on their $, which is nice). The runs are on a Dynojet (278e?) and they did 3 runs for the baseline data. My air/fuel ratio is much more lean than Joey's as above 4k it oscilates from 12.0 to about 13.0 with a mean of about 12.5. I'll get all the plots when the car is done and I can scan them and get 'em posted.

We found some additional things to fix (as one might expect). The unexpected has that the metal frame that supports the engine in the rear was bent at the right side motor mount. The metal was obviously fatigued and it was only a matter of time before it failed. I'll try and get a picture. A friend had a failure of the same part on his 993 last year at a track event. It made a real mess of his engine.

Lots of miscellaneous leaking seals and gaskets to replace and the power steering belt is in need of replacement. My dual mass FW was still functional but allowed a lot of play and the clutch was not dead but fairly worn. The car has about 74k miles and I'm not sure if the clutch has ever been changed. The sheet metal that surrounds the engine is all pretty corroded and they need to decide to replace it or clean and powder coat it. Given the clean up needed and the unexpected parts that need to be replaced, it may be a few days before the engine goes back into the car for it's next dyno run.

bhensarl

Did you head over to the dyno yet, Tom? I know you said in another thread that you'd already put the LWF in, but are the headers and chip in yet? I'd love to see those plots.
Brian

Tom W

Brian,

Headers and muffler were on last week. The chip was delayed (foul words deleted) so I took the car to Laguna Seca with the work incomplete (at least the engine was back in). I was more than a little anoyed that the car failed sound even though the vendor promised it would pass. At this point he has promised to make good on the promise to meet sound. He shold have shipped some replacement parts to the shop today for installation tomorrow to get it to pass. The shop is trying to get all ready for me to take it to LS again on Monday and see what it does. The chip goes in tomorrow and they hope to get it to the dyno by Friday.

So, at this point it's still a work in progress with a few bits to fix and the exhaust to be tweeked. With luck, I'll know more as the week progresses and have a good report to make on Tuesday. With the sound problem I didn't even try to get any lap times last week as the would be meanigless (I had to putt-putt past the sound station to avoid a black flag). With the chip in and passing exhaust, I'll be looking at my times to see how they improve (I'd really like to break the 1:50 'barrier').

garrett376

Hah!!! What a bummer - I had a feeling you would not make the sound with that kind of setup. That's the reason POC might drop that track as a venue since they have a unique way of measuring sound unlike any other track - it's a tough one to pass with!!! Good luck on Monday and keep us posted!!!

By the way who do you run with on these odd days (a Monday!)?

bhensarl

Thanks for the update, Tom. Believe me, I completely understand your use of expletives when dealing with the delay due to parts orders.
Even though you didn't get to get solid lap times, what do you think about the general running characteristics, even without the chip? Butt dyno results so far?
I'll be interested to see how you make out.
Brian

Geoffrey

Your AFRs are consistent with what I've seen other 964s show on the dyno with a big rich section at peak torque and then running lean as you head to redline. Performance exhaust systems, or anything that improves airflow, and therefore, VE% through the engine will worsen the problem. An aftermarket chip company can correct the map, and if you have a 90 brain with the fuel quality switch, you can richen it up 3% or 6%, however, it does make the it richer across the board. The aftermarket chips do increase power, but it comes from timing moreso than the air fuel ratio.

Tom W

Brian: I would say minor improvements from the exhaust change and LWF. My shift points were pretty much the same so I was not going much faster. However, my lap times at Laguna Seca are much more a reflection of the driver's skill than the car's capabilities. Whioe I can get to a low 1:50.x, the car should be capable of a 1:47-1:48 (or less, based on better drivers in similar cars). I just have to learn to quit over-braking before turn-in.

Garrett: Last week the Monday date was with TracQuest (they were also there Tuesday, but I had to work). Next week it's NCRC. A nice place to see who's running where is available here.

Cupcar#12

Tom
Can you post your graph with A/F shown? i would like to see how lean it is running @5K +
it should lean out at 4.5K but i'm wondering how much your is. 100 octane could be responsible for the increase - this would allow it to run on the extreme edge of the maps

Tom W

Rob, I'll get the before and after plots when all the work on the car is complete and I pay for it. I plan to then scan and post them.

The chip that is to be installed is designed for 98 octane. For the EU contingent note that this is (R+M)/2 octane. The 100 stuff that VP Fuels sells in CA is typically R=104 and M=96. IIRC, the EU fuel is equivalent to our "R" values (and I know that someone will politely correct me if I have it wrong )

Dunasso

Tom you guys are making me salvate. Quick someone get me a napkin.

On a serious note Tom, you didn,t think the flywheel and headers made a difference? I'ldlike to hear more on this.

Duncan

Tom W

Duncan, I'm sure it made a difference - just not a big one (I really didn't expect a big one either). First, keep in mind I hadn't driven the car on the track in about 3 months and had maybe 30 miles on the street in the back and forth from the shop. So, a real comparison in "feel" is hard, but I can say no profound change in performance at Laguna Seca.

There were some threads from a year or two ago on the 993 board (after I had done the LWf on my 993) and someone posted the physics behind the improvements the LWF makes. IIRC, the biggest benefit was in 1st and 2nd gear. That would make a street car feel better (and it does) but Laguna Seca is almost all 3rd gear for me. I shift to second at turn 11 before the main straight, climb to 4th before turn 2, back down to second briefly and then it's 3rd gear until back at turn 11. I could shift to 2nd at the corkscrew but it doesn't help and is unsettling to have to short shift in the middle of the quick left and then right turns as you descend through it. I usually stay in 3rd. Who would have thought stock gearing would work so well? I hit the rev limiter in 3rd (105 mph) just before turn 5 and then again just before the corkscrew (turn 8).

So, I should be back at LS on Monday (I hope so!) and will get a chance to run and check for differences with the new chip and (hopefully) a muffler that passes sound so I can run full-out. Then, the Hot Lap will tell me about improvements in real-world numbers and the dyno will give its input. The mechanic said the chip was going in today, so maybe dyno numbers tomorrow and a post with plots after I pick up the car on Friday or Saturday.

Christer

Duncan, I got a proven 17rwhp or so out of my GHL system. £2000 for 17rwhp....you can judge whether it was worth it...