adrs2k

Sounds like you had an awesome weekend!

odb812

Yeah, I'm SF SCCA but I'm new to the club. Actually I just got the 3-day membership this weekend, but after this weekend I'll become a regular member.

Thanks, it definitely was. I wish I could have driven a little better, but now I have motivation to push it harder next time.

iLuveketchup

I'm surprised STR is not the biggest class in your area. Being that the STR cars are right at home with the Cali weather (granted SF has its own cool micro climate).

odb812

That's what I figured as well. Especially since so many people in the area like to do both track and autocross in the same car and drive to and from events, STR is the perfect minimal set of mods for a street/track/autocross car. I looked at the results from last year, though, and there weren't that many drivers in STR last year either. There were only 4 other S2000s there this weekend. One was the other car in STR with me, another was in B stock, another was in one of the mod classes, and I didn't see the 4th run in any group but it looked stock. There are a lot of S2000s in the area, though; there were at least 10 of us at the track this weekend.

odb812

I've got the second STR autocross of the season coming up this Sunday at Marina Airfield. Saturday I'll be driving the S2000 for fun in Redwood PCA autocross at Santa Rosa Airport, which is an awesome venue.

This past weekend I spent a little time with the flashpro trying to smooth out the curve right after VTEC engages. I sometimes go as low as 5k rpms during runs, so I lowered the engagement point to 4700 rpms so I would have power at 5k. I was able to smooth the AFRs at the VTEC engagement point a bit more than the charts from the dyno, but there's still a dip. There must be something I'm missing about how the ECU determines fueling when switching from low to high speed fuel maps.

//steve\\

Look up lots of posts by Gernby. You'll never get rid of the dip as long as there is a cat on the car. You can minimize it but a fully catless exhaust seems to be the only way to completely rid yourself of it.

adrs2k

Get a high flow cat and you should be able to lower vtec to 3600-3900 rpm. I have a TP and full exhaust and my original tune was set at 3900 rpm from Evans, but my local tuner raised vtec to 4200 rpm and actually found 5lb ft of torque.

This dyno plot shows a few things. The bottom most line is a stock S2000, the thin red line was the evans tune, and the thick red line on the top is my final tune.

http://www.flickr.com/photos/41071623@N03/6834570008/http://www.flickr.com/photos/41071623@N03/6834570008/ by http://www.flickr.com/people/41071623@N03/, on Flickr


For more reference, a friends CR with a Berk 70mm HFC was tuned on the same dyno. I made 1whp more peak, and 10 lb ft of torque more at peak. The area under the curve though I averaged about 20lb ft more throughout the whole power band.

I realize this is your build thread and this plot doesnt really belong here, but thought maybe you would want to see it. Let me know and I will delete it out of here.

odb812

I've been reading a lot of Gernby's threads in the Engine Management forum and he's provided some great info for DIY tuners. I'm glad others have had this issue with the stock cat, it was driving me nuts that I couldn't smooth out the AFRs like there was something obvious I was missing.

Thanks for sharing. Any good technical info to add to the conversation is great. Did you make any other changes between the Evans tune and your local tuner's? It looks like he picked up torque everywhere. Besides moving the VTEC window, was he mostly working with timing?

There's a local guy selling a 63.5mm berk hfc that I'm thinking of picking up. Eventually, I'd probably add the berk 3" catback to drop some weight, but not at first. That looks like it could get me going in the right direction.

adrs2k

I am not sure exactly what the changes were other than vtec. I took my car in for a tune because I trust UMS tuning and have driven a few S2000's that they tuned. The Evans tune was actually a final version and the car was rough, and had some low speed bucking at partial throttle. UMS tried to clean up the Evans tune but ended up throwing it in the trash and re-tuned my car using another CR tune they had. I do believe timing and even the fuel tables were changed. I am hesitant to buy a header or any other part now because I dont want to mess with that torque curve!! The car is awesome now and I can leave the car in third gear on track and I save a lot of time by not having to use 2nd gear .

If you plan on going 3inch down the road, I would at least get the 70mm HFC then. Either way though, you def need the HFC to fully unlock the flashpro's potential. I have a 70mm TP btw.

odb812

I mostly got the flashpro to widen the usable power band rather than picking up more peak power. My goal was for autocross to avoid too many 2-1 downshifts and to get a few more mph on top of second, but the wider power band was really convenient on the track, too. There are a couple places at Thunderhill where I normally could shift to 5th for a couple seconds. I found it to be as fast and a bit easier to just leave the car in 4th and back off the throttle to stay at the rev limit, but now I can avoid the shift and get those extra few mph with 300 more revs.

I'm unsure about the 70mm, I'm still unclear whether the defouler is legal in STR. I'm not sure how much performance is to be had from an extra 7mm diameter for that small a section anyway. It would be nice to be able to use a tp or the Gernby pipe, I could probably smooth things out more, but class rules say that's a no-go.