Left Hand turn fuel starvation on WOT
 

I'm getting what feels like hiccup fuel starvation in/just after fast left hand turns followed by WOT, like 110 degree corners right after a sweeper into a straight, never when on a full tank, but consistently at 3/4 tank and below. Wondering if anyone else is having this. I dont recall it being NA, so I will be asking folks who track that go FI, cant replicate on the street, just not the same traction as rcomps on a track. LMK. I have this on two different tracks different fuel sources. Can make it happen on a cold pump.

I'm FI at 10psi on OE fuel system. I know folks will say go to higher output pump, but not sure thats diagnosing problem.
Oil temps were high both full tank and not full tank, both times it happened. Went to gas station filled up car with car and oil way hot, and no issues, so its not an hot oil temp driven event

Can not replicate with street tires
Must have R-comps, must be driving at 10/10s

WOT thru sweeper --->STAND ON BRAKES--->downshift--->Turn FEVERISHLY(feathering throttle to rotate rear end at break neck speed) --->then milliseconds right after apex go full WOT and go wide onto a straightway(INSERT hiccup)WOT at top of 2nd gear,sometimes event at beginning of 3rd, then this straight goes to 4th then another silly hard left, but no sweeper before it. and it doesnt happen there at all.

feels just like what happens when you make too fast a turn on a low fuel tank

I wasnt logging fuel rail pressure, next time...

anyone else?

Welcome to the world of aftermarket power. :(

Sounds like fuel starvation to me. Your fuel pressure log would confirm. Larger fuel pump isn't the solution. A surge tank is. Been there. Done that. It's a slippery slope because there are other potential issues with running a surge tank.

Thanks for posting the info. This is valuable information to know.

If it's not doing it when the tank is full then it should be fairly obvious what's happening.

You're going to need either an improved swirl pot in the tank, or look at an external one.

Ok, I have a really stupid question, because I think I already know the answer (Which is: yes, they are)--you have the nannies off, right?

i think you need more NOS.

10/10ths at a DE eh. I would like to see an EcuTek log file to diagnose what the issue is.

Fuel starvation.
@robispec has a similar problem on left sweepers; he's on E85. I've discussed the issue extensively with him but will let him go into more detail. We have some speculation on the causes and fixes, and he'll be testing it shortly.

Do you have ANY datalog from when you get the starve? I may be able to extrapolate something from it.

Off topic, but this can be fixed via proper suspension balance (front/rear rates) and/or a 2 way LSD. You can alter it with sways, damping changes, or tire pressures, but those are all bandaid fixes.

csg, the car handling fine,TOO fine perhaps

... its a fast corner in both cases...pm me your email address and I send you logfile to look at
something needs to be done to allow the 'bowl to fill faster

I'm not babying it when it happens

mike @t counterspacegarage d0t com

I think the car is not returning enough fuel to keep scavaging the fuel sloshed to the off side tank sump. the stock system does this using an "eductor" pump aka running extra fuel (the fuel exccess or the return fuel) by a nozzel set at an angle to the liquide flow wich pulls the fuel out of the rt sump and into the fuel pump antistarvation can.

saw something on sprtsguys build about the tube inside the pump being pinched? just throwing it out there...

I wonder if this is what killed the fuel supply to my car on a skid pad last month. I was also going left. Car wouldn't restart for 5 hours.

Scott

have you considered getting fuel foam? it is more known in the morotcycle racing world to keep the fuel from sloshing back and forth and upsetting the bike in switchback turns.

teh foam comes in little cubes and is simply stuffed into the fuel tank right up to the brim. it displaces next to no volume of the tank too.

I am guessing that since it isn't happening to you at a full tank that fuel sloch is your problem, and since you are FI your pump is consuming fuel so fast that it is getting air when the fuel sloshes.

That reminds me why I changed my mind about wanting a Cayman: too many reports of engines blowing up in left turns. Search '987.1 oiling issues'.

Most are on the track w/ sticky tires but some are off-ramps etc on the street.

this is looking better and better lol

Might consider this for my ITA car which has a stock tank. What's the degradation rate of this foam? How does it withstand E10 fuel and how often does it need to be replaced?

You have to tools to log these issues, I am surprised you are not constantly data logging, when you are out running this hard?

here is a quick ebay link: http://www.ebay.com/itm/10-Gallon-An...#ht_838wt_1156

I am not sure of the degradation rate if any. I have never used it or really read up much on it.

Yeah, heard about the fuel cell foam in bikes as well.
Quick search has a lot of people raving about this stuff:
http://www.fuelsafe.com/store/foam-baffling.html
I have read that you may need to replace it more frequently and that you may need to run another filter but it may be related to cheaper foam. Everything else i have read, the guys linked above are still the first choice in foam baffling. Most complaints are about the cheap stuff from Jegs and Summit.

so...news update

had a good long talk about this..

I am not alone, @robispec has experienced the same issues, so its about carrying high G's thru a corner (he is way lower CG and I am way pushing my r-comps)and pulling fuel out of the bowl just afterwards of a high G event and going WOT-not pump limited, and thats why I have not put a aftermarket pump in, it will only make it worse.

Per Robi, he is about to put his OE pump back in, as it in fact does get worse with the higher flo pump...so that made me feel better about what I had been theorizing from my tests, and we have arrived at identical conclusions, him on NA e85 and me on FI pumpgas, so bigger pump is NOT the answer. Thats the problem rather.

While none of you will ever see this on the street, tho it is a very real issue for those who track it at the limit. As I expect the problem to be worse doing the 12psi testing I'm about to do, it makes me hesitate tracking the car that way, it makes me worry about lean----? leading to Kaboom! and so I think its good to know the track limits of the oe fuel setup,
and the risks goes up as boost goes up

Robi and I agree, the solution is out of the box, meaning the oe fuel tank and setup is where the problem lies, it was never made to do what we are asking it to do. This is gonna slow down my testing, since unlike many guys happy with a dyno chart and a few passed cars on the street, I'm not happy till this thing runs like a wristwatch out on the track

tentatively I'm firming up plans for a visit out to see Robispec to deal with the fuel issue as a priority, end of May is when I plan to be out there for car work. I'm looking at a custom fuel cell.alum solution from him, as its clear he's already ahead of me with recreating the problem and finding a solution, this will be a good, I'm looking fwd to working with Robispec.
If we can solve teh fuel issue, then it makes sense to continue to make it faster, both in corners and in straights, so that helps me continue on to adding better suspension parts-right now I'm fuel limited in corners when I am anything but full of fuel, so adding front control arms, be it Robi or racerx, will need to wait till I solve the fuel issue. If that goes well, I may be up for the robispec cooling kit too...

those of you who have no clue what this is, it will require you either run a high flo setup, like robispecs tuned e85, or FI with high fuel demand, go spend a bunch of time on the track and you will see this thing rear its ugly head, its systemic, not build specific..we have seen it gets worse with adding a high flo pump alone
EDIT:Update,I'm looking into the dynosty solution as well.

this will be something that anyone and everyone who tracks, as your skills and build increase, you will all need once you max out the bowl refill capability on the oe plumbing. Its the magic combo lefty hander, slosh, tank level etc

I broke the dongle on my ecutek key while lapping, so theres a small gap but usually I am logging, I wasnt logging the fuel rail pressure value that day tho.. next weekend I have the opportunity to track but no dongle...so ... waiting on ecutek and @PERRIN_Jeff to help me recover from that one

confirmed we are working on a 2 pump swirl pot, solution and a full custom cell as well (visions of the NASA 25H running in my head Drivers/sponsors lets talk).

Thanks to you and @robispec for working on this issue! The more I think about it, this really explains what happened to me on the skidpad!

Scott

No thanks on a higher mounted aftermarket fuel cell. I would rather see a new fuel pump bucket solution. I know you guys are not the only two out there running 10/10ths on track. Has anyone else had this issue?

We gonna take on 949? :D

Miata vs FRS?

I believe the issue is from their respective cars having higher rates of consumption (boost in one case, E85 in the other).

I'm honestly surprised that a stockish car has starvation issues. We ran at ACS with no issue, even with the gas light on (14 degree banked turn, sustained for over 10 seconds, nearly 2G lateral)

That would be awesome. I loved watching the show about the 25 hours this year. It is actually the only thing I have saved on my DVR right now, haha.

I was thinking about Jon Miller setting the TTD record at Roebling last weekend. He was on an E85 tune and some serious grip, but Roebling really only has two left hand turns.

its going to be in stock location...rip out old tanks, put in new
by now you know, I go to try and test out whomever's solutions I like* and I think I am liking this alot

Lots of STi guys who do a lot of tracking end up using surge tanks. I used one of these in my 02 WRX so I could run almost no gas in the tank. You would be surprised what a small tank like that can do even for long sweepers.

http://www.hyperflow.com.au/index.ph...d=hyast-wrx001

Long sweepers do cause more issues. I think Phil @ Element Tuning (who seems to have disappeared) was getting minor fuel starvation last year even in a stock car when he first started running his car with big slicks.

See below:


http://www.ft86club.com/forums/showp...1&postcount=17

And some posts down:

for me its long sweeper on throttle-->[brake]greater than 110 degree left[accel]-----> straightway that seems to be a good test model

I considered a surge tank but its really a band aid, and becomes a smaller and smaller bandaid as you make more and more power and add more and more G's, if you dont fix the problem with the main tanks, the surge is kinda temporary fix and yes, I agree 100% it could well be the solution to- this all needs to be tested

I dont think this is the same tank in this car as in STI

I would suspect all foam will deteriorate eventually. We've had it happen in fuel cells using good foam, but it took several years to do so.

I'm sure it's not the same tank. I've seen guys in WRX/STi's use them in cars pushing 600WHP and other cars even more. That's using a setup with say dual Bosch 044 pumps. It's a solution if you don't feel like using an actual fuel cell.

Foam deteriorates, I wouldn't use it in anything but an actual fuel cell which you can take it out easily. And don't use it with E85. I've heard of guys using wiffle balls with success. Not sure you could put those in the tank though. :)

@Huehuecoyotl I appreciate your in depth testing on not only this issue but many others ranging from pentosin to Vortech. I know my question is off topic so I apologize..you mention that you're not satisfied until you have it running like a fine tuned watch on the track. I grew up racing dirt bikes and shifter karts so I can appreciate that but in my old age, dyno tuning for 93 and E85 is about as far as I go. So my question lies within your lap times. I'm sure you frequent a local track and I know you started tracking the car when it was almost new. Where were your lap times then and where are they now after FI, suspension, etc? Just curious to see the improvement in time on a track in comparison to the mods you have completed. If you have another thread discussing that already, link me up.

Thanks again,

Chad

Youre very welcome, I do the testing for myself, but know its a community service too.

Even tuning for 93 or e85, what we do to say we're done on a dyno and what we learn on the track after many logs allows my tuner to build a file for me(and likely you and other customers) thats made using real world data, in a far from ideal set of conditions vs a dyno room.

Up till this point it has run like a watch, so I didnt have this issue with the my lower power levels, so each time I go up in power I try to track in between, for my own benefit,again.

As I dont have the baselines you want on hand, what we will do is take my wifes car which is a bone stock BRZ with a TRD drop in, vs mine 'well built' on a day I'm renting a transponder(I dont when I am just tuning,testing and logging) I want to share that data too!

@ acs I starve in the rock garden before the straight
@ brp 13 ccw coming off the riverside into the bus stop
@ chuckwalla going through the huge lefthander (3-4 i think).

all big FLAT lefthanders no issues in the banking at all.

All can be managed by a short shift to 6th but the power is not there...then

We should see if the aftermarket pump still has the issue when you're running a 91/100 octane map... or have you already done this?

its the piping flo and return rates not the pump itself
I too am consistent @ FIR West before the straight when doing CCW and @ amp after the 180turn CW-both Flat as a pancake

My bet is a pump wont cure this...I will be game to see what Dynosty is up to but they been making power, not sure if they have the same G force induced stuff we're seeing in only the flat in same conditions of use, different pumps, different tunes, different fuels, this isnt a fuel supply issue thats pump limited, its limited by return rate I think

don't run 91 at the track...lol

e85 ftw lol

but will need to at chuckwalla... or have a 2 second margin! car only makes about 12 more WHP but the temps are all cooler!

Don't have the budget to run 100 :(