Left Hand turn fuel starvation on WOT

[jack43]

virtual Nurburgring:

[ame="http://www.youtube.com/watch?v=fv53RbvgfGc"]http://www.youtube.com/watch?v=fv53RbvgfGc[/ame]

(Sorry to derail the thread - just a cool vid.)

[orthojoe]

Now that this topic has come up, I do recall that the shape of the gas tank on our cars is shaped exactly like the tank on my Evo X. It's a saddle bag shape, and the fuel pump is on the left side of the tank. My Evo X had fuel starvation issues with long sweeping left handers going WOT. Turn 7 at Thunderhill gave me fuel starvation everytime even with 2/3 tank full. The Evo was as serious gas guzzler. I'd go through 1/2 tank after one 20 minute session, so you'd get fuel starvation even if you started off with a full tank. I haven't taken the BRZ to Thunderhill yet. Hopefully it won't be an issue. Doubtful given I'm stock power and tires, but the Evo would starve in stock form with stock tires (just not at 2/3 tank, more like 1/2 tank)

[Huehuecoyotl]

From where I sit adding more g's forward or laterally, adding more grip or adding more HP past where I am at is futile till I get rid of this behaviour. I have a tune for higher octane but thats gonna add Gs and make it all worse...I mean I got enough power now, maybe a bit too much...LOL

[AZFA20]

I think a lot of it has to do with the bowl design as we talked about. I don't think the pump is necessarily the problem either. I think the bowl is not being replenished fast enough as your fuel is all being sloshed to one side. There are band-aid solutions to this issue as we talked about on the track last weekend but I think going the route you are considering would be the best solution especially with the amount of track time your vehicle is seeing. This way it is no longer an issue at all whether on the street or the track. I am curious to see what Robi has up his sleeve for a stock replacement tank and sump.

[Dezoris]

Its going to be hard with where you guys are at, basically there are only a few of you pushing the car to this level. Anyone else doing it is a works shop. I think at this point what you are doing is prepping a race car and now you have engineering level problems most people will never have to deal with. I guess in a way its good for everyone else, but honestly I have to ask what is your end game?

[dave-]

Did this ever get to a solution? I'm on E85 with semis and finding the same problem at Phillip Island GP circuit in AU. Always the final corner which really kills my run onto the straight. Was never a problem on street tyres as I wasn't carrying as much corner speed.

I thought it was tune or hardware related but it does it no where else and only if the fuel is below ~3/4? If I keep the tank near full the issue disappears.

Video attached is my quickest lap there, start of the video is the middle of the corner, goto about 1:40 for the full run through the problematic corner. Speed is from about 100 to ~180km/h, constant left. The long right at 1:20 in the video is same speed range but obviously the fuel is being sloshed towards the pickup so starvation isn't a problem.

[ame="https://www.youtube.com/watch?v=slQnMA1eSJw"]Toyota 86 - Phillip Island - 1:52.1504 - YouTube[/ame]


Keeping the tank full is a cheap and easy fix so I'm not really prepared to spend massive dollars doing custom tanks or anything like that. But if there was a way to do something relatively affordable intank I'd consider it. Carrying an extra 20-30L of fuel has to be worth a few tenths hehe.

[AyJay]

1st time i ran at Thunderhill after switching to E85 i experienced this problem at Turn 8 (high speed left hander). It started out as a sputter when my tank dropped below 1/3 on the gauge. It behaved much like the traction control fuel cut for a brief second. I kept running laps that session since I wasn't sure what the hell was up and eventually it had to limp the car back onto the paddock as it would just sputter as if it was in some sort of limp mode.

My solution was simple. Never start a session with less than 1/2 a tank of E85 and replenish after every session. Haven't had an issue since.

[dave-]

Originally Posted by AyJay

My solution was simple. Never start a session with less than 1/2 a tank of E85 and replenish after every session. Haven't had an issue since.

Yeah obviously that is an easy fix.

I just assumed that by now someone would have come up with an actual solution which didn't break the bank.

[AyJay]

Sometimes the easiest and most obvious fixes are the best ones.

[jpky16]

Hmm i'm running basically a stock car (intake, exhaust, and Whiteline camber bolts and anti-dive kit) at the Ridge Motorsports park. Back when I had RS3s this was never a problem but now I am running RE71Rs and if i'm even at 3/4 tank on a good run i run into fuel starvation coming out of turn 6 (big left sweeper) which kills my run.

Did anyone ever get a fix for this? Or do i need to lose 20 minutes driving to the nearest gas station every time to fill up that last 1/4?

[Jonsey]

Moto-East surge tank is the only off-the-shelf product available right now. Others can probably put together a kit, but theirs is ready to go and well thought out. I can run E85 down below a 1/4 tank without issue now; I couldn't finish a single 20-minute session before the surge tank without fuel starving.

[redlined600]

Why not run 2 pumps? I know the BMW guys do it.

[dradernh]

Originally Posted by jpky16

Did anyone ever get a fix for this?

In the event you haven't read these, here are some threads talking about specific solutions:

See post #21, Phil Grabow's (Element Tuning) take on a solution: http://www.ft86club.com/forums/showthread.php?t=59735; more here: http://www.ft86club.com/forums/showthread.php?t=15188; and more here: http://elementtuning.com/2013/09/11/...13-frsft86brz/. Search the latter for 'saddle' to find the specifics.

Here's an example of the same solution applied to E36 BMWs: http://www.bimmerworld.com/Intake-Fu...ation-Kit.html

tldr; as @redlined600 suggested: two pumps.

[dave-]

Didn't realise I posted on this 2 years ago, still not solved 100%!

That was with completely stock fuel system and N/A E85 only. I'm now turbo so has become much worse obviously. In hindsight, not sure why I went FI but that's another story...

Started with a DWxxx (don't recall the number, 65c maybe) pump fitted in the original bucket

Added a second OEM bucket setup on the opp side, feeding back to the pickup but made it worse. Don't know exactly how it was setup in the tank tbh.

Then replaced the DW with another original bucket setup out of a wreck as we thought maybe the original bucket and o-rings had been butchered to fit the DW pump and was causing issues. Still no good.

Effectively the car is undrivable in its current state anywhere with constant left turn as the combination of E85, turbo and grip means having to lift for so long I end up almost as slow as a stock car!

I'm thinking in theory both my OEM pump setups feeding an external surge tank (2-3L maybe?) would have it being supplied left and right. Return back to the OEM tank so it doesn't pressurise (which I assume is what you want to avoid) should solve the problem in theory but I don't really want to waste any more money for a maybe.