[peterhemm]

I’ve had my SFR Stage II turbo kit for about a year now and I’m still learning how best to take advantage of the “hairdryer”. The most vexing issue is learning how to get back on the gas after lifting while under boost without upsetting the ECU.

Here’s a typical scenario: I’m cruising in 5th approaching a long hill climb. I drop into 4th and start accelerating strongly as the boost climbs. I reach my intended speed and hold the throttle position as I pull strongly up the hill. The problem comes in if someone interrupts that flow, say moving into my lane to get around a slower car. I let off and the boost drops, then when I get back on the gas I have to be careful not to open the throttle too much or the car bogs, the engine light starts blinking, and the car goes into a sort of “limp mode” that only clears if I shut off the engine and restart (something I’ve learned to do on the move without pulling over!). Having a diverter valve certainly helps reduce the time lag of the turbo coming back up to boost after letting off the throttle, but I'm still learning how to stay ahead of the turbo when driving hard.

The big lesson driving with the turbo seems to be one of unlearning some "normally aspirated" habits, not reflexively downshifting, giving the turbo time to spool up, and trying not to react too quickly to the boost dropping off. Does anyone have any words of wisdom on all this?

Thanks,
Peter

 

[Mister_smart_LA]

I’ve had my SFR Stage II turbo kit for about a year now and I’m still learning how best to take advantage of the “hairdryer”. The most vexing issue is learning how to get back on the gas after lifting while under boost without upsetting the ECU.

Here’s a typical scenario: I’m cruising in 5th approaching a long hill climb. I drop into 4th and start accelerating strongly as the boost climbs. I reach my intended speed and hold the throttle position as I pull strongly up the hill. The problem comes in if someone interrupts that flow, say moving into my lane to get around a slower car. I let off and the boost drops, then when I get back on the gas I have to be careful not to open the throttle too much or the car bogs, the engine light starts blinking, and the car goes into a sort of “limp mode” that only clears if I shut off the engine and restart (something I’ve learned to do on the move without pulling over!). Having a diverter valve certainly helps reduce the time lag of the turbo coming back up to boost after letting off the throttle, but I'm still learning how to stay ahead of the turbo when driving hard.

The big lesson driving with the turbo seems to be one of unlearning some "normally aspirated" habits, not reflexively downshifting, giving the turbo time to spool up, and trying not to react too quickly to the boost dropping off. Does anyone have any words of wisdom on all this?

Thanks,
Peter

Likely too much turbo boost for your current tuning levels. You can look into that, or perhaps look into beefing up the tuning of the rest of your engine including fuel flow rates, air intake temps and air flow, etc,.

I'm not sure how your SFR Stage II turbo is designed because I have never used one of those or turbo'd a smart. But I would first check to see if the wastegate is functioning properly, and for any plumbing leaks that may be causing an overboost condition.

 

[1983JZR3W]

You may want to PM Jet Fuel. He is the resident "hair dryer" expert on this forum.

 

[peterhemm]

Likely too much turbo boost for your current tuning levels...

I don't think it's a matter of too much boost (this setup is for 8lbs and the mechanical boost gauge confirms that as the cutoff), but rather managing a quick transition from on-boost to off-boost and back again. The vast majority of my spirited driving stays within the sweet spot of the turbo boost and I'm REALLY happy with the performance level, but there are sometimes when my pre-turbo "muscle memory" kicks in and I downshift when I should have been patient, stayed in that gear, and let the boost build back up. Ultimately, living with a bolt-on turbo is about learning how to avoid conditions that upset the ECU, sometimes a tricky task when in the heat of the moment!

 

[Mister_smart_LA]

I don't think it's a matter of too much boost (this setup is for 8lbs and the mechanical boost gauge confirms that as the cutoff), but rather managing a quick transition from on-boost to off-boost and back again. The vast majority of my spirited driving stays within the sweet spot of the turbo boost and I'm REALLY happy with the performance level, but there are sometimes when my pre-turbo "muscle memory" kicks in and I downshift when I should have been patient, stayed in that gear, and let the boost build back up. Ultimately, living with a bolt-on turbo is about learning how to avoid conditions that upset the ECU, sometimes a tricky task when in the heat of the moment!

I'd still go back and try reducing your boost levels to see if the problem goes away. If you're REALLY happy with the performance level, it's probably because pushing 8 lbs of boost is more than sufficient considering the naturally aspirated DNA of the 999cc engine.