Road Racers: Fuel pickup in long lefts

[Slow old poop]

In a long left turn, I have trouble with fuel pickup. Problems start at about 3/4 tank, with an occasional hiccup; at half a tank and below, it backfires, stumbles and coughs, the knock count goes up to 19, and then the temperature goes up from running lean. It only happens in one corner (so far), a very fast, very long left at Midamerica Motorplex that starts with a sharp turn in at about 70 mph, followed by a long run to corner out in 3rd and 4th. At corner out, I am up to about 100 mph, so I must be in a continuous left turn for 5-8 seconds.

What's the cure?
Fuel cell? (I still drive to the track, so I'll need at least a 10 gal tank.)
Put baffles in the tank?
Center the fuel pump?
Install a second fuel pump on the right side?

All ideas welcome

Rich

 

[MNGSX]

I would slip a mini cell or AKA surge tank under the intake manifold..

This is the high dollar solution..
http://www.atlinc.com/racing/bbox.htm

The low buck but just as effective way is a mini cell used as a surge tank.. The size all N20 drag cars use for the wet N20 fuel enrichment...

http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=2506&prmenbr=361

Drag race vertical 1 gallon....

Feed the 1gal with the intank out back and run the vent line of the cell to the oe return line to the rear tank...

use a inline pump on the front cell... Return the FPR to the mini cell...

It will always be full with some pressure in it from pushing extra fuel back to the rear tank...

 

[terefic181]

Slow old poop

I had a similar problem this year, a number of times, on a long right hand decreasing radius sweeper, on one of my last run sessions of the day. It spit and sputtered from around the apex point to a little past run out, when I got the car straightened out again. I did run my stock tank pretty low on fuel that run though, and attributed the problems to not enough fuel in the tank. The amount of fuel in my tank was quite a bit less than your describing. I think I started out with a little above a 1/4 tank showing on the Gage and ran a total of about 20 min.

If your really having that much trouble with it and attribute it to fuel loss do to slosh, you might want to go ahead and put a fuel cell in. You would want the black box as described in the URL above, and the foam, to go with it, for that very reason. The only major problem with heading down that road, is the expense, and there is a short life on the fuel cell bladders now. They're good for a total of 7 years if you return it to the company of origin at 5 years and have it re-certified.

You probably know this, but you may need to be carefull what materials you use if you go with the surge tank idea. The rules with the all the major sanctioning bodies for a road race car fuel cells etc., is much more strict than for a 1/4 milers. No poly, plastic, or inexpensive fuel cells are allowed, now. Only the FIA approved bladder type cells that have the new FIA certification and are in date are allowed. A surge tank of aluminum might fill that bill, but you should check with your sanctioning body.

After saying that, of course this would probably only apply if you're running with a sanctioning body, or plan to in the future, and would probably not apply for just a track day for street cars.

Good luck,

Tom

 

[Greg Collier]

I'm running a 13 gallon ATL fuel cell and still had fuel starvation until I installed a sump. Now it pumps fuel even when I'm spinning out...

 

[Turbo Shogun]

Maybe you should put more fuel in the tank.

Seriously, though ... I have run into that problem many a time now, and I'm thinking baffling the stock fuel tank is looking to be a good solution (anyone against this?). I've been told that keeping your fuel above 3/4 full will give the pickup enough fuel during those long sweepers, but I've run mine at half tank and it was alright. I autocross more than I attack road courses, though.

 

[Slow old poop]

1. Maybe you should put more fuel in the tank.

2. Seriously, though ... I have run into that problem many a time now, and I'm thinking baffling the stock fuel tank is looking to be a good solution (anyone against this?).
3. I've been told that keeping your fuel above 3/4 full will give the pickup enough fuel during those long sweepers, but I've run mine at half tank and it was alright. I autocross more than I attack road courses, though.

1. It's hard to keep the tank full at a track. Besides, that means hauling an extra 100 lb or so of fuel around the track all the time. When I go for a lap time, I like to be as light as possible.

2. Baffle the tank? How would you do that? Has anybody ever baffled a stock tank? Just cut it open, stick in some foam, and weld it back together?

3. I don't think you'll see this problem in an autocross, because you aren't in a turn long enough. Like I said, it only happens in one corner, a left that goes on and on. If it wasn't such a critical corner, I'd just cool it through there. Alas, cooling it would cost several seconds of lap time.

Rich

 

[stealthTT]

Hi this is Mike. I do most of SlowOldPoop's engine work (installs, tuning, etc.). I just finished researching surge tanks when I came across this post.

I think that's the way we should go. I'd like to know what you guys recommend for pumps. He has a walbro 255hp in-tank right now. Most people recommend a Bosch 392 or Aeromotive A1000 for an in-line pump. Or is an in-line walbro 255 good enough? It's half the cost. And because it's driven to the track, driven all day, and then driven home, will we need one of those expensive controllers to keep the temp down on the pump? Any thoughts or recommendations?

I'm going to check the NASA website and see what they say about aluminum tanks. We could weld one up easily enough.

Later, Mike.

 

[Slow old poop]

Hi this is Mike. I do most of SlowOldPoop's engine work (installs, tuning, etc.). I just finished researching surge tanks when I came across this post.
.

Ah, you finked me out, Mike. Yes, it's true. I am just the shoe. My wrenching consists of working on things that require no in-depth knowledge of all that...that...TUNER stuff. I do brakes and change tires and other non-techie stuff, like waxing and polishing, and I buy a lot of beer.

Without Mike and my other friends, I could not maintain a race car in the tune it takes to do well out there. I would have to buy a stock M3 or something, not a fun car like a GSX. Thankgawd we have a sweet little ricer/racer community here in Iowa, and wizards like Mike the Mechanic who love to go racin'.

Mike built me an absolutely ferocious 3000GT battleship last year. Alas, it spun all four tires at 100 mph, put us into the grass at MidAmerica Motorplex, and scared the peanuts out of me. (AWD wheelspin, the first time it happens to you, feels like you hit a little dirt, so you keep your foot in it--the right thing for dirt, but the wrong thing to do when all four are spinning. Problem is, it's hard to tell the difference between dirt and wheelspin.).

After that harrowing episode*, I decided I wasn't going out there again without a bar or a cage. I sold the battleship** and bought a prepped GSX that has a cage, and Mike and I are at it again. This GSX is not as fast as the battleship, but Mike is still working on it. We'll see what happens when Mike figures out how to run 29psi boost safely. I have confidence that we'll see 29 psi at Road America in October. I whupped up on Doug Rippey 427 supercharged Corvettes with the Battleship, and I would love to do it again with my little 4 cylinder economy car GSX.

Rich

*The corner worker said he had never seen a car go off there before. We were exiting a turn at 100+ in 3rd gear at WOT, where the 3000GT makes maximum hp (about 600 at the crank, we figure). It spun all four tires, and around we went for a wild ride through the grass.

**The battleship is out in California now, so if you see a very low, evil-lookin' black 3000GT coming up in your mirrors, better walk softly stranger. It's in the hands of a better driver now, and I have great hopes that it will terrorize the California M3s and Z06es like it did back here.

 

[stealthTT]

I didn't intend to fink you out. I just didn't want to come out of left field talking about what "we" were doing to your car. And you've come a long way Rich. I remember when you didn't know how to check the fluid in the tranny. Then after you helped pull the motor, you learned how to turn a wrench. Now your helping us diagnose and fix your problems.

And your claim of just being the shoe is grossly inadequate. This guy ran rallies before I was even a glimmer in my dad's eye. He has a million racing stories and you can learn a LOT over a few beers with him.

p.s. I did some looking through the NASA rules and whoa are all those rules about car safety enforced (window net, arm restraints, etc.)? If so, we've got some work to do this winter.

 

[terefic181]

Mike,

I'm sorry to be a party pooper, But Yes!
They are strictly enforced. Also if you change things before your in the race classes( still in HPDE etc.) Your car is checked as if it were in the race classes, and all changes have to meet the race standards.


Tom

 

[cait sith]

There's something by SARD that was made to address this issue.

The only issue is the legality in whatever sanctioning body may not approve of it.

http://store.yahoo.com/rotorworks/safucota.html

 

[Greg Collier]

If you're racing in NASA the car will probably end up in the "Super Unlimited" class and we all know what kind of competition runs there. The specifics regarding power, weight, suspension, brakes, tires, etc., is unlimited but safety requirements are universal. From fire suppression, min. roll cage construction, tube thickness and material type, seat and its attachment, tow hooks, etc., and there are quite a few, will be inspected throughly. They also do surprise inspections during the session where you will be fined $$ for any violations. 2006 will bring new requirements including neck restraints like a HANS device. We had a neck related death at a race at Buttonwillow at the end of 2003 and it really sucked.

It's all good as far as I'm concerned and it's all expensive. But what's your life worth?

 

[Turbo Shogun]

1. It's hard to keep the tank full at a track. Besides, that means hauling an extra 100 lb or so of fuel around the track all the time. When I go for a lap time, I like to be as light as possible.

2. Baffle the tank? How would you do that? Has anybody ever baffled a stock tank? Just cut it open, stick in some foam, and weld it back together?

3. I don't think you'll see this problem in an autocross, because you aren't in a turn long enough. Like I said, it only happens in one corner, a left that goes on and on. If it wasn't such a critical corner, I'd just cool it through there. Alas, cooling it would cost several seconds of lap time.

Rich

Well, not necessarily full ... Just 1/2 to 3/4s of the way there. I don't know if anyone on the forums has ever baffled (put metal "dividers" with "trap doors" into the fuel tank to keep it from sloshing around) their fuel tank, but I sure as hell will make it my winter project (still don't know if this is a good idea). And yes, I've starved my poor car of fuel during and out of long, high-radius corners and slaloms.

But at that point my fuel level gauge was barely scraping the 1/4 tank marking ...

Cait Sith - How does that thing work? WTF

 

[MNGSX]

Just get a in tank "fill bucket" from a newer LS1 f body.

The ones with plastic tanks have them..

Kind of like the little black box surge tank in tank on a buget for std tanks..

Racetronixs sells them with twin walbros.. A little tweak and it will probably go in a DSM tank..

Basically a mini tank that gets topped off constantly sitting in the tank... Even at 1/16 of a tank the fill bucket is full and the pumps submerged...

You must be logged in to view this image or video.

www.racetronics.com

 

[stealthTT]

If you're racing in NASA the car will probably end up in the "Super Unlimited" class and we all know what kind of competition runs there. The specifics regarding power, weight, suspension, brakes, tires, etc., is unlimited but safety requirements are universal. From fire suppression, min. roll cage construction, tube thickness and material type, seat and its attachment, tow hooks, etc., and there are quite a few, will be inspected throughly. They also do surprise inspections during the session where you will be fined $$ for any violations. 2006 will bring new requirements including neck restraints like a HANS device. We had a neck related death at a race at Buttonwillow at the end of 2003 and it really sucked.

It's all good as far as I'm concerned and it's all expensive. But what's your life worth?

I have no problem with installing safety devices. All the little things just started adding up as I read through the list. I am pretty sure when I read through the list a couple years ago that list was much smaller. But insurance and accidents probably helped the list balloon. We'll have to see that everything is "brought up to code" this winter.

Any suggestions for places to purchase some of these specialty items? I know of racerwholesale.com

Thanks for all this help. I didn't think people road raced dsm's or just didn't talk about it on forums.

 

[terefic181]

Rich, Mike,

I usually pick up quite a few things from Racers Wholesale. Restraints, window net etc.

NASA seems to always change at least a few thing every year. The New CCR is usually issued around January of each year, sometimes later. Once you get the car up to NASA specs this winter you might want to take it to an authorized NASA inspection shop and get your log book signed off as the car being current. That way if they change something major (IE. roll cage specs) You'll probably be grandfathered in with the way the car is, rather than having to change things all over again. I spent a great deal of time putting my cage in and they were about to change the specs by requiring DOM tubing only, so even though I was still in HPDE, that's what I did, I got the car cleared, and received the race log for the car, prior to that regulation being instituted.

Just a thought ,

Tom

 

[Dauntless]

Just get a in tank "fill bucket" from a newer LS1 f body.

The ones with plastic tanks have them..

Kind of like the little black box surge tank in tank on a buget for std tanks..

Racetronixs sells them with twin walbros.. A little tweak and it will probably go in a DSM tank..

Basically a mini tank that gets topped off constantly sitting in the tank... Even at 1/16 of a tank the fill bucket is full and the pumps submerged...

You must be logged in to view this image or video.

www.racetronics.com

Yes, these are the ultimate answer, whether with stock tanks or fuel cells. I have similar (though aluminum) setups in both of my road racing cars. They will suck virtually all the fuel out of the tank. In one car we pumped out all the fuel to send the bag off for repair. When we removed the bag through a small access panel we found less than a cup of residual fuel, which I'm sure had simply not had sufficient time to fully drain from the foam.

For those who aren't familiar with the dual pump setup, one pump sucks fuel through the mesh screen partially seen at the bottom of the white plastic tank in the photo above. It fills the tank and then simply overflows back into the main tank. The second pump pressurizes the fuel system from the pint or two of gasoline in the white tank, which stays completely filled until all the fuel in the main tank is exhausted. The white tank is only a couple of inches across, so no matter how violent the turns the primary pump still has plenty of fuel to lift.

 

[cait sith]

Cait Sith - How does that thing work? WTF

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Basically what it does is a lot like that F body thing/seperate fuel cell, but holds 5 liters (one and a third gallons, bottom single pump setup), second one (Top photo with accutriments for double fuel pumps) holds almost six liters (1 and a half gallons).

You run a line from your stock fuel pump to the surge tank, then run a secondary pump that steals all the fuel from the small surge tank, which then leads to the fuel rail. Run a return to the surge tank and then a breather/secdondary return line to the main tank.

I don't think you'd be pulling that much slosh for over a gallon.

Like I said though, you'd have to check with your governing bodies on their rulings before running something like this I assume.

 

[MNGSX]

That was in post #2 by me..

 

[cait sith]

Yeah but you can throw a cheap wally in a SARD tank instead of a more expensive inline.

 

[terefic181]

Yes, these are the ultimate answer, whether with stock tanks or fuel cells. I have similar (though aluminum) setups in both of my road racing cars. They will suck virtually all the fuel out of the tank. In one car we pumped out all the fuel to send the bag off for repair. When we removed the bag through a small access panel we found less than a cup of residual fuel, which I'm sure had simply not had sufficient time to fully drain from the foam.

For those who aren't familiar with the dual pump setup, one pump sucks fuel through the mesh screen partially seen at the bottom of the white plastic tank in the photo above. It fills the tank and then simply overflows back into the main tank. The second pump pressurizes the fuel system from the pint or two of gasoline in the white tank, which stays completely filled until all the fuel in the main tank is exhausted. The white tank is only a couple of inches across, so no matter how violent the turns the primary pump still has plenty of fuel to lift.

This set up does look promising. Looks to be, most likely, as good as the (black box) sump system, they sell for fuel cells, maybe better. I would certainly be interested in seeing if it can be retro fitted, fairly easily, to our stock tank.

Tom

 

[Turbo Shogun]

It looks like a cheaper solution to the SARD surge tank as well ... Looks like I'll be making a few calls today.

Instead of running two walbros, I was thinking I'd use my stock pump to fill the bucket while retaining my Walbro 190 for the engine ... Should be much cheaper then.

 

[MNGSX]

Just get another pump and a piece of PVC with a cap.. mount the first pump and sock on the cap and bolt it to the OEM pickup with the second pump pulling from the bucket...

 

[Turbo Shogun]

I may have found a less expensive and easier solution to surging tank woes ...

http://www.performancecenter.com/au...ervice_parts__and__accessories/hol12-951.html

How they work:
Have you ever sprayed water on a window screen? Recall that the screen will actually hold some of the water. These pickups work the same way. When the pickup is submerged in fuel, gas will pass through the mesh with ease. When fuel sloshes away from the pickup, the mesh will hold enough fuel to fill all the tiny holes. That mesh full of fuel acts like a solid. At this point, the pump, sucking on the outlet will cause the mesh to suck shut, preventing the pump from sucking air. When fuel covers the pickup once again, the valve will open up and transfer fuel.

These pick-ups have one or two 5/16 fittings. The pickups with two fittings can be used to connect pickups in series.

Walbro suggests that at least one pickup in the system should have a bleed hole. If your system doesn't have a bleed hole, it can become totally closed if all of the pickups close at once. If that happens, the closed pickups can take several minutes to re-open, depending upon how much vacuum the fuel pump has pulled.

The inlet side of the pickup has a 70 micron mesh. The pickup is just under three inches in diameter and just under two inches tall. These pickups have been tested in gasoline to -40 F and in diesel fuel to 0 F.

Note:
If the fuel pickups are completely dry, the pump will suck air. The pickups won't close unless they have been initially immersed in fuel [the mesh is wet].

This seems like a little half-ass ... I'm starting to think if the fuel held in the little sac will be enough to tide the pump pickup over for prolonged periods, but I guess that's why you need to use multiple pickup points.

 

[1LE]

Switch to a 2g? The don't have the problem until you get down to 1/4 tank