My sequential twins are functioning perfectly. However, on occasion the transition point can be a little rough. As we all know this can cause issues when you're accelerating at part throttle in a corner -- if the transition isn't perfectly smooth it's going to upset the balance of the car, especially if you're cornering at the limit. This has happened to me and it's a little frustrating/unnerving. Is this enough motivation to go non-sequential? Should I concentrate my efforts on smoothing the transistion by adjusting the prespool bleed? I'd like to hear other people's experience here.

 

Once you breathe the car out (open exhaust, etc), the transition isn't really smooth anymore... you get that wack! when it transitions... mine does it. You can just drive around it, or get used to it. In most cases, you're keeping the revs up above 3k (when the computer resets from twin mode back to primary mode) anyway. Where are you dipping down low enough that it's a problem?

 

Yea, maybe that's it then. I have DP+catback, intake, i/c etc. It's pretty good most of the time, but just on occasion is it pronounced. That and I'm on the stock ECU and I hear tell that grounding issues or whatever can cause part throttle hesistation at ~3500 rpm which could also be a contributor.

I usually only downshit from 4th to 3rd entering, for example, turn 5 at Summit main. Then as I continue to accelerate through 6 and 7 it catches up to me in that series (I shift back to 4th after I straighten out through the uphill section). I guess I could drop to 2nd entering the carrosel, but I'm on street tires and the amount of throttle control required to keep the rears from sending me off the track in 2nd gear in the tight sections is probably what's keeping me in 3rd. Maybe next year when I get better tires I can maintain more speed through that series and not worry about it, else I can play with going from 4th to 2nd.

 

Are you Group 2 at Summit?

I'm hitting the FAAT this friday, why don't you come out...

 

Yea, last month's event would have been my last in HPDE2, but now with the crash I'm probably going to stick around for a few more events to see how badly my confidence has been shaken before moving up to 3. I need to address some issues with the car before getting on the track again, so probably not till next year (VIR in Feb?) That and I've got a rally in NJ on Saturday and a rallyx in PA on Sunday so this weekend's pretty booked already.

Have fun this weekend!

 

I would check on your turbo control components. Myself and several others have had no problems with harsh transitions on modified FD's. Up until I blew my motor ( ), most people use to comment on the fact that my car's transition was almost non-existant.

However, learning to roll and not stab the throttle can help as well. IMO, its about learning the characteristics of the car and being able to drive it. Sure, you can change it, but what fun is there in that?

 

Is your boost like 12-8-12 or 10-8-10 ? Or is it much like 12-6-12 or similar ?

 

Haha, simple question and FD boost transition never belong in the same sentence.

I'd play with the prespool adjustment if you can. Worst case it won't get better and you'll simply have to be gentle thru transition, after all it is just a track day. The fun is in the braking and cornering.

Dave

 

Well, could be also slow TCA operation as it needs both vacuum and boost to operate quickly. And a dip to 5 or 6psi at transition would should that.

 

I run about a 9-8-9 boost pattern with a manual boost controller. I've found that if i lower the boost slightly, I can run intake/ic/exhaust with stock ecu and not experience any boost creep on stock twins with unported WG.

 

I can 13-8-13 without ported WG and dont get boost creep. There is no fixed rule

 

Tires will allow more speed there ... I have to hit 4th before the right up the hill. Similar mods, but with R-comp tires. How do you control boost now?

Transition will likely be a cronic problem with street tires on the track.

 

Single ball/spring type MBC controls both WGA and PGA.

 

With a 9-8-9 pattern, you should consider yourself lucky, that's pretty consistent, and should be fairly smooth. I think you're just wringing your hands after your accident, and need to get back on the horse.