Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB

- Tracking / Autocross / HPDE / Drifting (https://www.ft86club.com/forums/forumdisplay.php?f=39)

- - Mechanical overrev, 9k (https://www.ft86club.com/forums/showthread.php?t=145262)

Quote:

Originally Posted by ZDan (Post 3431428)

The issue also correlates with not starting session with a full tank. But yeah, the 1st time it happened was only a few laps after the overrev. Engine sounded extremely valve-noisy to me but then I listened to my bud's same-year 86 and it makes the same noises (mostly injector noises I think). We have similar setups, and our acceleration plots fell right on top of each other so my engine is performing normally otherwise.

Still, I was thinking that maybe VVT mechanism(s) might have been damaged and might quit "VVTing" after a few laps, but why would it reliably fail at exactly the same spot on the track every time? @CSG Mike's post about starvation "under the right conditions" is hugely encouraging. Heavily banked 180-degree left-hand NHMS Turn 6, with a little flat table top I use at track-out, while continuing left into Turn 7, on tires that honestly feel faster and more confidence-inspiring here than even 8-cycle Hoosiers I was on last fall, might all add up to "the right conditions".

Bingo.

Fuel pickup is on the driver side.

I also get the the loss of power ,with exhaust backfiring, after a double left hander that links(Fish Hook). 6k rpm in 3rd on semis with less than a 1/2 tank or 3/4+ RHD. Must be fuel as I have not revved past 7.6k and it only happens when you nail the section.

Can someone school me, isn't our rev limiter set well below 9k?

Quote:

Originally Posted by 54fighting (Post 3431795)

Can someone school me, isn't our rev limiter set well below 9k?

One Scenario.. 4th gear 7.5k rpm and shift into 5th, but you hit 3rd gear by accident. Mechanical over rev! 9k rpm give or take

Quote:

Originally Posted by 54fighting (Post 3431795)

Can someone school me, isn't our rev limiter set well below 9k?

Not an issue with auto, but with a manual, you have full control over the gears and revs. An extreme example, but the ECU can't stop you from shifting into 1st gear going 60 mph. The rev limiter is only controlled under acceleration, not through gear changes, as this is purely mechanical.

Quote:

Originally Posted by jflogerzi (Post 3431309)

ecutek would should show these as well which he has access too.

Would this be able to check our ECU for evidence of an overrev event? And if so, how can we find it? Thanks.

Quote:

Originally Posted by RKTSGN (Post 3451063)

Would this be able to check our ECU for evidence of an overrev event? And if so, how can we find it? Thanks.

Only if it created a code but not over rev

Sent from my GM1915 using Tapatalk

Speaking of fuel starvation - whats the fix here? Aftermarket fuel pump?

Quote:

Originally Posted by Hades (Post 3452921)

Speaking of fuel starvation - whats the fix here? Aftermarket fuel pump?

Race car? Surge tank.

Quote:

Originally Posted by CSG Mike (Post 3452932)

Race car? Surge tank.

No not race car, more dual purpose track/street car. I guess there's not really a solution for that scenario?

Quote:

Originally Posted by Hades (Post 3453168)

No not race car, more dual purpose track/street car. I guess there's not really a solution for that scenario?

Just run a full tank.

Quote:

Originally Posted by CSG Mike (Post 3453182)

Just run a full tank.

Is this adequate with F/I + R-comps though? Sounds like F/I for a street car basically means no racing slicks/high Gs otherwise.

EDIT: Sorry to hijack thread lol

Quote:

Originally Posted by Hades (Post 3453210)

Is this adequate with F/I + R-comps though? Sounds like F/I for a street car basically means no racing slicks/high Gs otherwise.

EDIT: Sorry to hijack thread lol

Depends on the rest of the car and what exactly you want to do, but probably yes.