BigMike's Forum

24 Hours of LeMons (Now Open To The Public!) => General Performance Talk => Topic started by: BigMike on April 11, 2010, 03:55:51 AM

Title: Fuel Tank Considerations
Post by: BigMike on April 11, 2010, 03:55:51 AM
Okay,

According to Google Earth and the projected Buttonwillow LeMons track (http://www.jagpromotions.com/images/buttonwillowmap2.jpg), the short version is about 2 miles per lap and the long version is about 2.7 miles per lap.

Consider the following data:

Fuel Tank     |  Average MPG  |  # Short Laps per tank  |  # Long Laps per tank
Stock, 9gal52216
9gal + 5gal53526
.
Stock, 9gal83626
9gal + 5gal85641
.
Stock, 9gal104533
9gal + 5gal107051
.
Stock, 9gal12.55641
9gal + 5gal12.58764
.
Stock, 9gal156750
9gal + 5gal1510577

From a previous Buttonwillow LeMons event, the winner's average lap time was 2:50mins completing 281 laps total. I am not sure which track version this was raced on. Here is the data:

Fuel Tank     |  Average MPG  |  Hours Per Tank if Short Laps  | Hours Per Tank if Long Laps
Stock, 9gal51.070.79
9gal + 5gal51.661.23
.
Stock, 9gal81.71.26
9gal + 5gal82.651.96
.
Stock, 9gal102.131.58
9gal + 5gal103.312.45
.
Stock, 9gal12.52.661.97
9gal + 5gal12.54.143.07
.
Stock, 9gal153.22.37
9gal + 5gal154.973.68
.


edit: Additional calculation of this data shows that the 1st place car either averaged 42 MPH (if they raced the short track) or he averaged 57 MPH (if long track). Hey Bryan! What was your lap time again in the MR2 on Buttonwillow for the full length track?
Title: Re: Fuel Tank Considerations
Post by: BigMike on April 11, 2010, 04:01:39 AM
Before I made these calculations, I was thinking that we could add a small 5-gallon fuel tank to the front trunk. 5 gal of fuel only weighs 31 pounds, so with a tank, pump, and 1 line to the main tank, it wouldn't be more than 40 lbs max.

But after looking at the data, even if we average only 5 miles per gallon, in the worst case scenario we will get 48 mins out on the track per tank of gas. If we make 10 MPG, then this worst case will still get us a whopping 1 hour and 35 mins on the track without needing to pit.

I agree with what Bryan said at the 2nd meeting that we need to consider how long each driver can even stay on the track at a time. Is 1 hr 30 min segments inbetween pits too long? What do you guys think?
Title: Re: Fuel Tank Considerations
Post by: BigMike on April 11, 2010, 04:09:18 AM
If we transplant the 4A-GE into my car, then lets only put in 3 or 4 gallons and run it super super hard continuously until it runs out of gas, and then see what the average MPG is. At least this would give us a ball-park figure, plus my car is heavier than our LeMons car which would only help the cause.
Title: Re: Fuel Tank Considerations
Post by: kdogae86 on April 25, 2010, 08:59:20 PM
interesting subject. we need to ask brian how long each track session was that he drove and how he felt after. thats the only knowledge we will have in advance. this is all a big unknown until we go do it.
Title: Re: Fuel Tank Considerations
Post by: kdogae86 on April 25, 2010, 09:00:37 PM
put 4 gallons in the mr2 and drive it up tollhouse with a chase vehicle and see how long it takes to run out.
but tollhouse isnt long enough.
Title: Re: Fuel Tank Considerations
Post by: BigMike on April 25, 2010, 10:49:27 PM
Since things have changed a bit and the engine will remain with the car, I say let's tow it up to Bills and just his Tollhouse from his place. Just need to make sure to have a chase car stay close behind.
Title: Re: Fuel Tank Considerations
Post by: BryanH on April 25, 2010, 11:21:29 PM
If the fuel gauge works, that's probably good enough.  I can't recall for sure how long it took to go through a tank of fuel on my MK1 at the track but it was definitely long enough that a driver would welcome a break after a full fuel stint.  My trackday sessions were usually 20-30 minutes at a time, definitely not long enough to worry about fuel. 
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on April 26, 2010, 12:07:12 PM
Check the fuel comsumption as you would normally do, fill tank, run a few laps, fill tank, calculate. Only problem here is traffic. 1 pokey slow, and results are out the door. My suggestion is to run the back of Pine Flat. Minimal traffic, hardly ever see a cop. Or run out Burrough Valley/Maxon, R. on Watts, R. on Pittman Hill, R. on Sample, etc.. Back to Burrough Valley. Rinse, repeat. That should be about a 20+ mile course. Now, Who wants to volunteer to do the driving?!?!
Title: Re: Fuel Tank Considerations
Post by: BigMike on April 26, 2010, 12:51:20 PM
Now, Who wants to volunteer to do the driving?!?!

ooo! ooo! pick me! pick me!
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on April 26, 2010, 07:10:55 PM
Although, driving in the hills won't be accurate for flat land driving. Mileage be a bit better on the track I'm sure.
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on April 26, 2010, 07:53:27 PM
When kevin and I went to P-a-P for the throttle cable we saw a tank that looked like it would fit in the front trunk. Wasn't a very big tank either. Tanks material looked like it might be poly.
Title: Re: Fuel Tank Considerations
Post by: BryanH on April 26, 2010, 11:10:32 PM
Any tank that would fit in the frunk (without cutting it up) would only be a few gallons.  It would also change the weight distribution of the car as fuel burned off.  The stock fuel tank is actually in a really good location as far as balance, and doesn't have any pickup issues at high Gs (at least until you get really really empty). 
Title: Re: Fuel Tank Considerations
Post by: BigMike on April 27, 2010, 12:55:08 PM
This remains to be proved, but I think my calculations show that the stock tank will outlast driver intervals. If we make 12 to 15 MPG we might get 2 or 3 driver changes PER TANK. :o (of course we wouldn't want to risk running low on fuel, but I'm just saying...)
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on April 27, 2010, 03:22:10 PM
We can get the thing together, bring it up here, and we can all take it out for familiarization. At least the hills are a bit safer than the city streets. And we'll all (even me) have to agree not to run without a chase car. Communication and spotters would be a good idea too. Sounds like a team effort in the making.
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on April 27, 2010, 03:32:38 PM
As far as the mileage test runs, Mikey, I'm the better candidate. I live up here, and I know the roads better. To make sure of that I'm going out to practice RIGHT NOW!!
Title: Re: Fuel Tank Considerations
Post by: BigMike on April 27, 2010, 07:13:05 PM
^^ hahahaha I like this guy


Okay, team effort of chase cars & spotters. This is all sounding really really fun! Once I get my MR2 going I'm sure I'll be up there a bunch!
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on May 04, 2010, 10:15:17 AM
Go to LeMons forum/newbies/fueling questions. Maybe we could find a 55 gallon barrel to take fuel.
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on May 04, 2010, 10:18:51 AM
Power booster. mix ethanol with amonium nitrate inject into inake manifold at a %5-%10 rate. Hmmmmmm, how crazy are we(me myself and I the three of us).
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 10, 2010, 11:32:44 AM
Ok guys,

The black 1987 MR2, team "Stick Figure Racing", who apparently has a stock 4A-GE, told me they average 18 miles per gallon while racing. Our engine will have higher power output and it's possible we are more aggressive drivers, so my guesstimate is that we'll probably make 13-15 MPG.

I really think we should look into a small tank mounted in the front trunk. Even if its only 3 or 4 gallons, at about 6 pounds per galloin, that is only 18 or 24 pounds full, no more than 30 pounds tank+pump+lines.... I really don't think that will "destroy" our handling. Remember it will help our weight distribution and front traction when the little tank is full, and then it will just act like normal when its empty. I like to carry my 50 pound tool box in my front trunk and it hardly makes a difference in my car (granted my car is heavier).

I heard a couple of teams talking about how great it would be to have extra fuel storage for better pit stop management. They said there is a MR2 team running a 5 gallon front trunk mounted fuel cell reserve tank and it really helps them manage their fuel stops. They also were commenting how large cars have huge tanks by default, some up to 18 or 20 gallons. We are at a big disadvantage in this category with our little 9-9.5 gallon tank that we'll probably need to refill every 8 gallons (or else risk running out of gas while cornering if we really push for 9 gallons per pit). Maximizing our time on the track is going to be very important.

Also, I never saw any judges opening up trunks. Not once. If we don't say anything about it I bet they wouldn't even look. And if they do look we'll hand over all the documentation for it.

I know that our old Formula-Toy had a small fuel cell that we are not using. Maybe I can get it for our car, I'll have to look into it.

The best setup would be a fully automated system. We *could* have some toggle switch to pump gas from the reserve to the main tank, but that would be one more thing to worry the stressed out driver. What we can do instead is when the gas in the main tank gets to a certain level, say 1/2 or 1/3 tank, I will have a device that activates the pump in the reserve tank, pump all its gas into the main tank, and then disable the reserve pump. Piece of cake.

What do you guys think? I would like to do this for the March event if I can come up with a reserve tank that meets the safety & rule requirement. I'll take care of this entire reserve tank project so no one else has to worry about it. This will give us a serious advantage over other MR2s.

Mike
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on December 10, 2010, 11:55:09 AM
Consider a surge tank too. Might be an extra gallon or so, but the real advantage would be the protection against leaning out in a turn with a low tank.
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 10, 2010, 04:25:32 PM
CRAP. New rules for 2011 say we can only have 1 tank per vehicle... See this thread: http://bigmike.marlincrawler.com/forum/index.php?topic=190.msg1912#msg1912
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on December 10, 2010, 05:41:31 PM
Can't have a second tank? How about 30' of filler hose? 2" tube run parallel to the tank under the car hidden by the under body panels?
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 10, 2010, 06:24:51 PM
You know we could still stash a hidden fuel tank and get away with it. That is the nature of this whole event in my opinion. As long as its well concealed, safe, and trouble free, I don't think it would be a problem at all.

There is space beneath the curvature of the front trunk :idea:
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on December 10, 2010, 07:53:20 PM
I wonder if we could incorporate a hidden tank in the foam in the frunk? Use a little extra foam in the redirection of the radiator airflow.
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 18, 2010, 05:45:30 PM
Check this out

Last week I didn't have time to get gas before my Wed morning final, so I drove all the way to college like this. I've driven below the E line before so I thought it wasn't too risky. Sure would have sucked to have ran out of gas and missed my final! LOL The low level light is not on because the key is in the off position in this shot.

So with the needle below the E line, it took 9.12 gallons. So I'm guessing the tank is about 9.5 max and it'd probably stall before you got there.
Title: Re: Fuel Tank Considerations
Post by: BryanH on December 18, 2010, 07:29:40 PM
IIRC it's a 10.8 gallon.  I know I put 10.5 gallons in my '87 once or twice.  I figured out that once the fuel light came on I had at least 2 gallons left - so I never pushed it past 60 miles on the light (mostly ran low on long drives, not so much in town). 

With the SC and race tires I figured out the car will fuel starve at an autocross shortly after the light comes on.  Interestingly, it starved under braking.  As soon as I'd go to pick up the throttle again it'd hesitate for a bit, then accelerate like normal until after the next braking zone.

The more you know...
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 18, 2010, 10:05:31 PM
WOW Most interesting to know Bryan :yesnod: What I will do is the next time I am running low I will carry my spare 2.5 gallon tank with me and run the car dry. Then I'll throw the 2.5 gal in and get to the nearest station asap so we can see what the total capacity is at starvation.

You are correct with the braking. When my needle was on top of the E line, it would dip below it briefly during braking and also left hand corners. Right hand corners caused the needle to rise slightly.

I have _never_ filled 10 gallons in my 2 in my life. The most I've ever done is always in the low 9 gallon range. Now you've got me really curious! :thumbs:

Mike
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 18, 2010, 10:35:02 PM
I just spent a good 10 mins :working: the FSM and I can't find where the manual lists the exact fuel capacity.
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on December 19, 2010, 12:45:51 AM
Never got my 2 below the 1/4 mark, so no idea on the real useful capacity. When you changed the pump in your tank, did you get the pickup screen in the prooper location? or higher or lower?
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 19, 2010, 08:46:00 AM
If you are asking me, then I am not sure. The V6 Tacoma screen was a lot longer than the MR2 screen and it was difficult getting it to drop it without the screen clipping the top of the fuel pump isolation bowl (lack of a better description). I finally managed to drop it in so that the screen was pressing against the inside of the isolation bowl which I assumed resulted in the screen being pre-loaded against the pump, rather than being bent at an angle against the pump.

I know it works :gap:
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on December 19, 2010, 12:41:21 PM
Just a consideration for checking usable volume in the tank. Could give bogus info. Does the low level light work?
Title: Re: Fuel Tank Considerations
Post by: BigMike on December 20, 2010, 08:52:55 AM
Does the low level light work?
Yeppers
Title: Re: Fuel Tank Considerations
Post by: Sirdeuce on December 19, 2016, 09:53:29 AM
I wonder if it would be worth it to fab up a composite tank??? I found the right resin for the job and think using basalt as the material filler. Wouldn't have to worry about E-85 eating it up.