Fuel starvation in 3rd gen--solutions?
03-09-07, 01:32 AM
#102
I'm going to post the results of my simple cover which I believe is similar to the 96+ tank design. With the stock 94 tank I'm getting starvation at 5/8 of a tank on DOT race tires. We'll see how much of a difference the cover makes, if any.
-ch
-ch
03-09-07, 02:09 AM
#103
Originally Posted by FDNewbie
I have yet to see any *definitive* proof that the 95 tank is a significant upgrade. Just lots of rumors and speculation...My car with the '93 tank will fuel starve before my gas gauge even gets down to the 'Full' mark, at about 5-6 gallons used in left turns. The worst is at Road America, where there's a turn (6) at the top of a hill, the gas is thrown forward and up, and I will starve there at only 4 gallons used unless I'm careful. I can generally pull about 1.2-1.3g's in the same turn.
03-09-07, 07:27 AM
#104
Originally Posted by hyperion
I'm going to post the results of my simple cover which I believe is similar to the 96+ tank design. With the stock 94 tank I'm getting starvation at 5/8 of a tank on DOT race tires. We'll see how much of a difference the cover makes, if any.
-ch
-ch
:-) neil
03-09-07, 11:30 AM
#105
If you have a mid-94 tank or later, yes. The way to tell is if your fuel tank bucket has provisions for tabs or not. My car, a 94, has them:
Older tanks have the plastic bucket, but the perimeter of the bucket does not have those little loops built in. The only way to be sure is to look inside your fuel tank...
-ch
Older tanks have the plastic bucket, but the perimeter of the bucket does not have those little loops built in. The only way to be sure is to look inside your fuel tank...
-ch
03-09-07, 03:00 PM
#107
The bucket is a gravity feed system. There are two cases:
1) The fuel level is above the bucket wall (about 4" tall). In this case, the fuel completely fills the bucket
2) The fuel level is below the bucket wall. In the picture above you can see a small opening on the upper right side. There is a divider that runs left to right. When the car is level and not accelerating, the fuel comes through the hole and through hydrostatic pressure is forced into the bucket and fills it to the level of the rest of the tank. When cornering or braking, fuel can leave through the hole but the divider ensures that most of the fuel stays in the bucket--and drains relatively slowly.
The problem is that when you hit the brakes and go to 1.5G, all the fuel just launches right out over the sides of the bucket. The momentum of the fuel pushes most of it out, so the bucket isn't very effective. Supposedly, a cover can address this problem to some degree...I'll be testing mine (shown earlier in this thread) on Monday at the track to see if it makes any difference.
-ch
1) The fuel level is above the bucket wall (about 4" tall). In this case, the fuel completely fills the bucket
2) The fuel level is below the bucket wall. In the picture above you can see a small opening on the upper right side. There is a divider that runs left to right. When the car is level and not accelerating, the fuel comes through the hole and through hydrostatic pressure is forced into the bucket and fills it to the level of the rest of the tank. When cornering or braking, fuel can leave through the hole but the divider ensures that most of the fuel stays in the bucket--and drains relatively slowly.
The problem is that when you hit the brakes and go to 1.5G, all the fuel just launches right out over the sides of the bucket. The momentum of the fuel pushes most of it out, so the bucket isn't very effective. Supposedly, a cover can address this problem to some degree...I'll be testing mine (shown earlier in this thread) on Monday at the track to see if it makes any difference.
-ch
03-09-07, 04:34 PM
#110
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A little off topic, but, hyperion, did you go to Laguna yet? Wondering because me and a fellow fd owner will be there with NASA on the 21st. I'd love to see your car.
Matt
Matt
03-09-07, 05:21 PM
#111
weather until he's down at or below 1/4 tank, about 14-16 gallons used. Then he will start to starve on long sustained left turns (like turn 5-6 at MAM.) He can generally pull 1.4-1.5 g's in a normal flat 90 deg turn.
My car with the '93 tank will fuel starve before my gas gauge even gets down to the 'Full' mark, at about 5-6 gallons used in left turns. The worst is at Road America, where there's a turn (6) at the top of a hill, the gas is thrown forward and up, and I will starve there at only 4 gallons used unless I'm careful. I can generally pull about 1.2-1.3g's in the same turn.[/QUOTE]Understood. But the only reason I question the conclusion you're jumping to is, do we have any similar data from '94 tanks? Ie, is there anything special about the '95s that is different than the '94s? Or is this simply another case of '93 FDs being shafted in poor initial quality?
My car with the '93 tank will fuel starve before my gas gauge even gets down to the 'Full' mark, at about 5-6 gallons used in left turns. The worst is at Road America, where there's a turn (6) at the top of a hill, the gas is thrown forward and up, and I will starve there at only 4 gallons used unless I'm careful. I can generally pull about 1.2-1.3g's in the same turn.[/QUOTE]Understood. But the only reason I question the conclusion you're jumping to is, do we have any similar data from '94 tanks? Ie, is there anything special about the '95s that is different than the '94s? Or is this simply another case of '93 FDs being shafted in poor initial quality?
03-09-07, 05:45 PM
#112
Lives on the Forum
Originally Posted by FDNewbie
But the only reason I question the conclusion you're jumping to is, do we have any similar data from '94 tanks? Ie, is there anything special about the '95s that is different than the '94s? Or is this simply another case of '93 FDs being shafted in poor initial quality?
03-09-07, 05:48 PM
#113
Originally Posted by DamonB
The 95's have "improved" baffles around the fuel pickup. It's all relative. The 95's are not quite as bad as the earlier cars but the 95 baffle does not actually solve the problem.
And I'm specifically speaking of an improvement in the '95 tank over the '94 tank (not 94 and 95 vs. 93).
03-09-07, 05:50 PM
#114
Lives on the Forum
Originally Posted by FDNewbie
Damon, you're saying this w/ considerable confidence
It doesn't matter which tank we're discussing. They all starve badly, the 95's just aren't quite as bad as the earlier cars.
03-09-07, 06:17 PM
#116
Originally Posted by DamonB
That's because the 95 cars still experience the same problem.
It doesn't matter which tank we're discussing. They all starve badly, the 95's just aren't quite as bad as the earlier cars.
It doesn't matter which tank we're discussing. They all starve badly, the 95's just aren't quite as bad as the earlier cars.
Damian's car shows that if your goal is to make a 15-30 minute session on the track without starving, the '95 tank can do that. Just fill it up imbetween each session. The '93 tank is not sufficient for higher hp cars.
If you want to actually use all the fuel in the tank (down to, say 1 gal or less left,) you are correct, they all will not work.
FDNewbie, I don't have any data from a car with the '94 tank, sorry.
03-09-07, 06:28 PM
#117
Originally Posted by GooRoo
FDNewbie, I don't have any data from a car with the '94 tank, sorry.
From my experience, a whole host of modifications were made during mid-production in '93. These modifications were found on a good percentage of the '94 FDs, and ALL the '95 FDs. That's what I think the case is here as well. Yet the way ppl refer to it on the board makes it seem it's a '95 and up thing, exclusively - which I highly doubt. THAT'S what I'm seeking a clarification of
~Ramy
03-09-07, 07:11 PM
#119
If it helps, I have a 94' and I have only seen fuel starvation on left handers when my fuel level was around 1/4 or less. However I have only done a couple of track events on my car so far (it's currently in pieces waiting to be worked on).
As for the stock plastic bucket... how about replacing the "hole" in the side of the bucket with a check valve? Or maybe a couple of them, on several sides of the bucket. I think that coupled with the cover would be a good solution, basically like one of those trap boxes or whatever.
However I'd still like to know how big that box is... how long do you think the fuel trapped in the box lasts? Is it enough for a long high-G left hander?
As for the stock plastic bucket... how about replacing the "hole" in the side of the bucket with a check valve? Or maybe a couple of them, on several sides of the bucket. I think that coupled with the cover would be a good solution, basically like one of those trap boxes or whatever.
However I'd still like to know how big that box is... how long do you think the fuel trapped in the box lasts? Is it enough for a long high-G left hander?
03-10-07, 03:00 AM
#120
Originally Posted by rotoober
A little off topic, but, hyperion, did you go to Laguna yet? Wondering because me and a fellow fd owner will be there with NASA on the 21st. I'd love to see your car.
Matt
Matt
I go to Laguna this Monday with Trackmasters. I'm hoping to get my car sorted for regular track use...I'm waiting on a brake kit and I'm installing an Accusump in the next month or so. Plus I'm redesigning the cooling and intake system. What a project! Let me know what other track events you're going to--I'd be happy to take you for a spin in the car.
-ch
03-10-07, 03:04 AM
#121
Originally Posted by RaceDriver7
If it helps, I have a 94' and I have only seen fuel starvation on left handers when my fuel level was around 1/4 or less. However I have only done a couple of track events on my car so far (it's currently in pieces waiting to be worked on).
As for the stock plastic bucket... how about replacing the "hole" in the side of the bucket with a check valve? Or maybe a couple of them, on several sides of the bucket. I think that coupled with the cover would be a good solution, basically like one of those trap boxes or whatever.
However I'd still like to know how big that box is... how long do you think the fuel trapped in the box lasts? Is it enough for a long high-G left hander?
As for the stock plastic bucket... how about replacing the "hole" in the side of the bucket with a check valve? Or maybe a couple of them, on several sides of the bucket. I think that coupled with the cover would be a good solution, basically like one of those trap boxes or whatever.
However I'd still like to know how big that box is... how long do you think the fuel trapped in the box lasts? Is it enough for a long high-G left hander?
-ch
03-10-07, 03:11 AM
#122
Originally Posted by afgmoto1978
Sweet someone else has already done this! I plan on doing something very similar soon.
That said, I'm not crazy about the build quality, but that's what I get for being a picky bastard. I also don't like the fact that the bottom of the filler pump is not supported. Having all the weight on the fitting at the top is not optimal.
-ch
03-13-07, 03:07 AM
#124
Track Report: Laguna Seca, Monday March 12th
Well, some very encouraging news to report from my track day at Laguna. The short version is that the tank bucket mod allowed me to run down to below 1/4 of a tank--10 gallons less fuel than before. Details:
I started this thread after my last track day there in January where I was experiencing starvation in turns 11 and 2 (both left handers following heavy braking zones). I was getting engine cutout due to air in the lines at around 5/8 of a tank. (All tank measurements refer to what the gauge reads while stationary in the paddock.)
After some very helpful information and ideas from the forum--especially Gene Felber--I created a cover for the slosh bucket in the FD gas tank. Mine is a '94 and has slots built in for tabs.
At Laguna I ran five 20 minute sessions and took some notes along the way. My car has Michelin Pilot Sport Cups which are short of a full slick but are nonetheless an extremely sticky DOT road racing tire. I run 285/35/18 on all four corners and have a fairly aggressive suspension. This is only the second track day for these tyres.
Here's what the tank read at the start of each session.
Session 1: 3/4 tank
Session 2: 5/8 tank
Session 3: 1/2 tank
Session 4: 1/4 tank
I ended session 4 with the tank reading this in the paddock:
I put about 5 gallons in the car for the last session just so I didn't run out. After that I filled the tank which took a further 12 gallons. Based on my burn rate, I would say that I ran the tank all the way down to about 4-5 gallons without any starvation. This includes braking from 130 MPH and then going through a 200 degree left hand corner (where I had starvation issues previously).
The track was hotter than in January--bright sun and near 80 degrees air temp--so I would say grip was a bit better this time around.
I should note that during the sessions the fuel gauge drops 1/8-1/4 lower than what it reads at rest. For example, during session 3 the gauge was below 1/4 for much of the session, but when I came to rest it settled right at 1/4.
This is only one datapoint. I haven't autocrossed the car, nor have I run at a high-speed track where you have a series of high-G corners in sequence. However, it's very encouraging to be able to run down to 1/8th of a tank when before I was having trouble at 5/8.
I have no doubt that an in-tank surge enclosure or dual-pump system will work even better, and I've no idea if this mod will work for all applications. But for me, it's a big improvement!
There is an autocross this weekend that I may attend just to test a bit more. I may also go to Infineon on Friday if I can make the time.
-ch
I started this thread after my last track day there in January where I was experiencing starvation in turns 11 and 2 (both left handers following heavy braking zones). I was getting engine cutout due to air in the lines at around 5/8 of a tank. (All tank measurements refer to what the gauge reads while stationary in the paddock.)
After some very helpful information and ideas from the forum--especially Gene Felber--I created a cover for the slosh bucket in the FD gas tank. Mine is a '94 and has slots built in for tabs.
At Laguna I ran five 20 minute sessions and took some notes along the way. My car has Michelin Pilot Sport Cups which are short of a full slick but are nonetheless an extremely sticky DOT road racing tire. I run 285/35/18 on all four corners and have a fairly aggressive suspension. This is only the second track day for these tyres.
Here's what the tank read at the start of each session.
Session 1: 3/4 tank
Session 2: 5/8 tank
Session 3: 1/2 tank
Session 4: 1/4 tank
I ended session 4 with the tank reading this in the paddock:
I put about 5 gallons in the car for the last session just so I didn't run out. After that I filled the tank which took a further 12 gallons. Based on my burn rate, I would say that I ran the tank all the way down to about 4-5 gallons without any starvation. This includes braking from 130 MPH and then going through a 200 degree left hand corner (where I had starvation issues previously).
The track was hotter than in January--bright sun and near 80 degrees air temp--so I would say grip was a bit better this time around.
I should note that during the sessions the fuel gauge drops 1/8-1/4 lower than what it reads at rest. For example, during session 3 the gauge was below 1/4 for much of the session, but when I came to rest it settled right at 1/4.
This is only one datapoint. I haven't autocrossed the car, nor have I run at a high-speed track where you have a series of high-G corners in sequence. However, it's very encouraging to be able to run down to 1/8th of a tank when before I was having trouble at 5/8.
I have no doubt that an in-tank surge enclosure or dual-pump system will work even better, and I've no idea if this mod will work for all applications. But for me, it's a big improvement!
There is an autocross this weekend that I may attend just to test a bit more. I may also go to Infineon on Friday if I can make the time.
-ch