Since I've been doing some autocross racing I've put some more thought and effort into determining the right time to shift in my Accent. I figured that I would share my research and opinions on the subject. This is for my car specifically, but you can do the same thing yourself for your car if desired. If you have a 1.6l Accent this should be close enough to be useful for you too.

My Accent's power mods:
SRI
Evofusion 4-2-1 header
custom exhaust
phenolic spacer

My Accent's rev limiter RPM's:
1st: 30
2nd: 55
3rd: 82
4th: 108
5th: 135 (but no I can't go fast enough to hit it lol)

My Accent's Dyno:


Now here's a graph I've made to determine my shift points based on my dyno and my RPM's at each MPH in each gear. The small version is hard to read at best, but you can click on this link to see a more legible full sized version: Full sized graph



Any questions or comments?

 

wait what else do you have done? Thats what myt car hit and I have 30 more hp than you do. My car with 4-1 SR headers, bbtb, exhaust and SAFCII never got 30 MPH in 1st or even 80 in 3rd. Since the turbo I gained about 10 mph in each gear and right now my mph at redline is:
1st: 25ish (not much power in 1st)
2nd: 58
3rd: 84
4th 110
5th: Not sure still never taken it past 125

2nd through 5th I have a relativly significant pull than stock or N/A

 

Well it kinda depends on how it's being driven. My rev limiter cuts in in different places. Sometimes it's the soft one, sometimes it's the hard one. rolleyes.gif

1st 27-32 (usually 28-30)
2nd 48-54 (usually 50-52)
3rd 80-82
4th around 110
5th never hit it. yet. cool.gif

ETA: I have the stock 1.5 SOHC though.

 

<div class='quotetop'>QUOTE(Fintile @ Aug 18 2008, 11:58 PM) </div><div class='quotemain'>wait what else do you have done? Thats what myt car hit and I have 30 more hp than you do. My car with 4-1 SR headers, bbtb, exhaust and SAFCII never got 30 MPH in 1st or even 80 in 3rd. Since the turbo I gained about 10 mph in each gear and right now my mph at redline is:
1st: 25ish (not much power in 1st)
2nd: 58
3rd: 84
4th 110
5th: Not sure still never taken it past 125

2nd through 5th I have a relativly significant pull than stock or N/A</div>
The only things I have done that could have any effect not listed is Redline MT-90 in the tranny and Royal Purple in the crankcase plus minor porting and polishing to the stock IM to facilitate the BBTB. I pulled off the BBTB though due to some issues I've been having and it was not installed for the dyno run above. I've been meaning to IM you Fintile to talk about the BBTB and see if you were still looking for one and tell you what's been going on with my car.

Unless you've changed the ECU programming you'll hit the rev limiter at the same RPM and MPH regardless of whether you have 30hp or 300hp. With more power the engine may carry you to a bit faster than with less power, I.E. if you can barely get the car to pull to 80mph in 3rd in the first place you won't continue accelerating once you hit the rev limiter at all but if you're still accelerating quickly you'll pull a couple MPH past where you use to due to momentum.

As far as my speeds at rev limiter they're all based on indicated speed and all gears but 5th I went out and checked to see what MPH my car cut off at. For 5th I just went to 3125RPM's and doubled my mph because 6250 is about where my limiter kicks in. For me it seems to be at consistant MPH and the only gears that I can hit the hard limiter are 1st and sometimes 2nd. I hit 1st gear rev limiter a lot and it's always in the same spot. I hit it a lot because when I first shift 2nd gear is a pig in my car.

 

<div class='quotetop'>QUOTE(187sks @ Aug 19 2008, 03:24 PM) </div><div class='quotemain'>I hit 1st gear rev limiter a lot and it's always in the same spot. I hit it a lot because when I first shift 2nd gear is a pig in my car.</div>

I can't see your dyno because of my works proxy, but don't you have a flat spot in the middle of your powerband? That'd explain the poor performance: if you're at rev limit, then upshift into the small flat spot, it'd suck for a minute.


I'd just like to point out mine doesn't have the same "dead spot". tongue.gif

 

It's more of a low plateau in my car. It peaks at 100lb/ft around 2500 RPM's (it sure doesn't feel like that bump in torque is there), then dives down and holds at 95lb/ft until 4000 RPM's where it goes up to 100lb/ft again before dropping off while headed to redline.

 

OK I see what you mean...yeah I do go thropugh my gears quicker than I used to. SO I see the poitn with the redline and MPH mark. I used to shift around 5,500_6k before I had the turbo because I just didnt feel any power in the car after that so i would just shift it...with the turbo however i forget to shift sometimes because it just want to keep gaining power all the way through till redline.

What was wrong with the BBTB? Sticking too much? heh heh thats was the main reason I got rid of mine. That and the fact it doesnt do squat for an N/A 1.6, you might get a few trq down low but nothing that is too noticable to say its worth it. My trq sits fairly close to stock in the low end: 1k-3k ( still have about 80 ftlbs by 2k though wich is better than 60 stock) then it clims to 102 by 3k then it shots straight to 135-38 at 4k then starts to tapper off crossing my HP mark at 4,700ish where they are at 133 by redline I got about 126 trq so thats why I feel like it still just wants to keep going I got over 25 mor ftlbs thrusting it onward.

 

Are you asking for shift points for autocross or for track driving?

For track driving, I'd probably shift just before you hit the limiter. If you shift earlier you'll fall south of the powerband.

For autocross, you should mainly be concerned with getting out of first gear, basically shifting into second as soon as possible as the course allows. Usually I shift before the first major course elements so I can concentrate on driving. You shouldn't ever have to shift into third gear unless you're running shorter than stock tires, and even then its rare. The only time I've ever had to shift into third on an autocross course was at a National Tour course a few years ago where I was on the limiter for close to 10 seconds on my first run, and even then it was of dubious value since more often than not I screwed up the downshift.

 

This was a byproduct of me checking some things for autocross shifting, but the charts and shift points are not for autocross, probably more applicable to drag racing than any other kind of racing.

It's mostly something to show graphically an issue that's been discussed many times whenever someone asks when to shift their car.

All but 2 autox courses I've driven were 2nd gear only courses. One required a bunch of shifting and some faster cars were exceeding 90mph on that course's fast section ( I needed 3rd gear on a good run)and I had to shift down into 1st in another two sections. The other was a toss up so I let it sit on the rev limiter half the time but it was a good six seconds on the limiter.

It can also be useful (if memorized) for choosing what gear to shift down into for passing and things like that.