Superchargers only Please

[MarauderMark]

Now apparently you cannot run or give your car hard acceleration when your car is below 1/4 tank and now i am wondering if this is true for all superchargers or only a select few and if so which ones?. i have read threads here that say they less gas the less weight the more you gain a tenth or two and some have ran them low so they could fill with race gas.has anyone or maybe the question should be whats the lowest mark on your fuel gauge that you had your car run at wot and could the motor to detonate if the fuel did not go under 1/4 tank?sorry if this sounds stupid but any info would be greatly appreciated..:)

[juno]

The 1/4 tank thing is based on your tank design and not your pump. The stang folks use a cobra tank or modify the stock with baffles to keep sufficent volume to maintain a suction at the pump when you go to a larger pump. I do not know what folks have done to these tanks, but the 1/4 tank concept is a good comprimise to keep your motor together unless you have another way to maintain sufficent volume at the sucky end.

[FordNut]

It is true for all supercharged Marauders except Marty's. When you accelerate hard, the fuel sloshes to the back of the tank. If the fuel level is low enough (approximately 1/4 tank or lower) the fuel pump pickup will no loner be submerged in fuel so the pumps will get air in the lines. Whether the air is in small bubbles or in a large slug is irrelevant, there is not enough fuel reaching the injectors so the motor will go lean and kaPOW !

Less gas, less weight, better e.t. but only up to a point.

Not so serious a problem on n/a cars because of three things: they generally don't accelerate as hard, they don't require as much fuel, and a little pinging won't immediately destroy the engine without a blower.

On the street, without any WOT, I run mine well below empty all the time and have even coasted into the pumps a couple of times. But never beat on it when it's low on fuel. I try to run it a low as possible on the way to the dragstrip so I can put in race gas once I get there and I don't want to dilute the race gas with pump gas.

Another interesting fact, I had about 3/8 tank once and ran the "dragon". There were so many curves that the fuel was sloshing side-to-side in the tank to the point the gauge read below empty and the car died! Once it slowed down, the gauge came back up to 1/4+ and the car ran fine. This was prior to supercharging, so now I would probably not make a run like that with less than 2/3 tank.

The dragon: http://www.tailofthedragon.com/ 318 curves in 11 miles!

Edit: Marty has a sumped tank...

[Todd]

Now apparently you cannot run or give your car hard acceleration when your car is below 1/4 tank and now i am wondering if this is true for all superchargers or only a select few and if so which ones?. i have read threads here that say they less gas the less weight the more you gain a tenth or two and some have ran them low so they could fill with race gas.has anyone or maybe the question should be whats the lowest mark on your fuel gauge that you had your car run at wot and could the motor to detonate if the fuel did not go under 1/4 tank?sorry if this sounds stupid but any info would be greatly appreciated..:)


I have run mine hard with gas as low as 1/8 of a tank. But 1/4 is probably a better bet.... It has nothing to do with being supercharged or not, or what kind of supercharger you have. Although power adder cars will die a harder, quicker death if they have an issue.

The point is to not have the intank pickup come out of the fuel left in your tank. Lack of fuel at good accelleration is a sure way to smoke a few pistons...

[Smokie]

My alltime best ET and 60' times were achieved on 3/4 tank....go figure.

[Zack]

I always have my eyes on the Fuel pressure gauge at WOT when Im under 1/4 tank

[MikesMerc]

I always have my eyes on the Fuel pressure gauge at WOT when Im under 1/4 tank

Me too.


I can't say that I have ever raced the car with less than 1/8th tank....but I know I've been under 1/4 before lots of times without issue. In addition, I know that Jerry and Lidio haven't had any issues between 1/8 and 1/4 either. We all run some decent 60 foots too. Based on that, I don't think the Marauder has an inherently bad set up causing a major issue.

That said, I always, always, always recommend running no lower than just under 1/4 tank at the track. Its simply good insurance.

[Breadfan]

Wow, this is good to know. I never even considered this. My only concern at low fuel levels is the fact that crap in your tank will sink lower and you risk picking up more junk the lower your tank gets. Maybe an old wise-tale but been stuck in my head since my grandfather lectured me on it when I was 7.

[shakes_26]

I run with 1/2 tank or better at the track. The extra weight behind the rear axle helps launch. Other than that I haven't paid much attention to what the fuel level is when I hammer the car. On the street, traction is so limited you can't get the fuel to move that much, maybe at the track its an issue where you can hookup and really launch.

[Marauderman]

I'm with the 1/4 tank issue--meaning not less than--for the reasons Fordnut explained.....because when it goes bad , it goes very bad.....so why chance it--it's pretty much a known fact ....I think Fordnut explained it very well...thanks Brian..............Tom

[MM03MOK]

A full tank of gas weighs 117.2 lbs. (6.2 lbs. x 19 gallons). The difference between a 1/4 tank and a 1/8 tank is 14.725 lbs. (6.2 lbs. x 2.375 gallons.) For that amount of weight, a tenth or two is more likely many other factors than the weight of gasoline. Take out the spare to "lose weight" instead of chancing costly issues to the car.

[juno]

A full tank of gas weighs 117.2 gallons (6.2 lbs. x 19 gallons). The difference between a 1/4 tank and a 1/8 tank is 14.725 lbs. (6.2 lbs. x 2.375 gallons.) For that amount of weight, a tenth or two is more likely many other factors than the weight of gasoline. Take out the spare to "lose weight" instead of chancing costly issues to the car.

Good point Mary!!!!

[martyo]

It is true for all supercharged Marauders except Marty's.

Edit: Marty has a sumped tank...

A dry pick up will kill your motor quick! That is one of the reasons we sumped my tank. The other was the addition of a returning fuel system.

Zack is right. Keep on eye on the fuel pressure when you are running hard on lower levels of fuel. Even with the sump, we tend not to run my car with less than a 1/4 tank as the weight savings is just not worth it (like Mary said ^^^). Hell, I can empty more out of my bladder and get the weight savings that I need! :D

The sumping was not that big of a deal in the scheme of things for my car. Just remember, for the sump to be effective, the pick up has to be relocated too.

Good thread, good info.

[MM03MOK]

Hell, I can empty more out of my bladder and get the weight savings that I need! :D

I wasn't going to say that, but now that you mention it...! ;) :D

[Haggis]

Now apparently you cannot run or give your car hard acceleration when your car is below 1/4 tank and now i am wondering if this is true for all superchargers or only a select few and if so which ones?. i have read threads here that say they less gas the less weight the more you gain a tenth or two and some have ran them low so they could fill with race gas.has anyone or maybe the question should be whats the lowest mark on your fuel gauge that you had your car run at wot and could the motor to detonate if the fuel did not go under 1/4 tank?sorry if this sounds stupid but any info would be greatly appreciated..:)

Working on engine #3 right now..

Ok Mark, what did you do now?!! I do not need to repeat what others have already said above. Good advice all of it.

[SergntMac]

Any sudden loss of fuel to the engine under WOT is a serious complication, and the design/construction of the factory fuel tank plays in here. Imagine this in you head.

Problem one...The fuel tank is shaped like a briefcase, or, small suit case. Inside this vertical rectangle tank is an open end cylinder, a "soup can" shaped housing that shrouds (baffles) the fuel pump/pick-up. This cylinder/soup can fills from the top when the tank is more than half full, and from the bottom when low on fuel, low being less than 1/4 tank.

The fuel pump(s) feed from inside the can and it acts to baffle against sloshing fuel when motoring through the countryside. However, like Brian (FordNut) explains, when you run hard enough, you can suck the fuel dry from inside the can before it has time to refill.

In this case, the more efficient your fuel pumps, the more likely you are to suck the soup can dry under racing conditions. It just doesn't refill itself quick enough to keep up with the consumption of fuel under race conditions. Thus it's relationship to supercharging...Speed, time, consumption rate ect., all occur faster, when you are faster. 14 second N/A cars may not be affected. NOS cars with a fuel supplement may also not be affected, because the NOS makes up for the lean condition. Maybe.

Problem two...The OEM fuel pump is electric and internal to the fuel tank. Thus, there is a control module in the trunk on the driver's side, near the emergency fuel shut-off switch. This module monitors fuel pressure, pump load and pump voltage.

If it detects a problem with the electric pump, like the pump seems to have run dry (i.e. spinning too fast because of no load) or, the wires get to hot from added voltage (i.e. KB boost-a-pump), it calls for a fuel system shut down.

This module is largely a safety device to stop the fuel pump from dumping fuel after a collision, or, fuel system failure (i.e. broken lines/loss of resistance) thus, it reacts to low fuel supply too.

The module can be modified to work with improved fuel systems (i.e. larger lines, no 45 degree bends, larger filters, injectors, BAP and so on) and if it's not modified, a low fuel supply will shut everything down at the worst possible instance...WOT. Shut off the fuel supply at WOT, and you'll walk back to the pits.

This is why I race with a half tank of fuel and higher octane in the tank when I'm planning to run hard. I have sufficient improvements to my fuel system to be knocking on this problem's door, and a midified control module is on board. You can get your's through Dennis, about 100 bucks with your core module.

[Bluerauder]

A full tank of gas weighs 117.2 gallons (6.2 lbs. x 19 gallons). The difference between a 1/4 tank and a 1/8 tank is 14.725 lbs. (6.2 lbs. x 2.375 gallons.)
Actually, it may be even a little better than that. The Handbook of Chemistry & Physics lists the density of gasoline at 41.0 - 43.0 pounds per cubic foot. That translates to 5.48 - 5.75 pounds per gallon. Therefore, using Mary's 1/8 tank (2.375 gallon) difference, the weight difference is probably closer to 13.01 to 13.65 pounds or about 1-2 pounds lower than the figures above. :D

[MarauderMark]

Thank you ALL for your info as i have learned what i needed to know.:beer:

[wchain]

I have to chime in here. Supercharged or not The tanks in our cars sit up and down, and with 1/4 tank, thats around 4.5 Gallons.

I measured the tank in my Marauder, and its 18" top to bottom, so 4.5 gallons equals approximately 4.5" in the tank. The tank is also sloped forward. When accelerating, you will probably won't exceed 1g acceleration, so lets say your car is REALLY fast, and you CAN accelerate at 1g. (not even a Ferrari Enzo can do this) There is currently NO car that can accelerate at 1g. Accelerating at 1g, theoretically, the fuel is at a 45 degree angle in the tank. A S/C Marauder at LAUNCH is MAYBE .8g, higher the speed, more forces working against it, such as wind, friction from the tires against pavement, and heat. Forces of 1g acceleration pushing it to the back of the tank, and gravity, downward force also 1g trying to level the fuel at the same time, worst case scenario.

So lets say the average g's during a quarter mile run is .4g, not hardly anything to 'slam' fuel to the back of the tank, since the tank is sloped forward. Theres also a coffee can type 'sump' sitting in the bottom of the tank, where the pump sits and picks up fuel, sort of an anti slosh device. So if your fuel level is too low to enter the 'sump' and you are actually consuming more fuel than can enter the sump, yes, you will encounter this problem, but this is at a VERY low level, i.e. <1 gallon in the car.

If you were asking this question with a 1/8 tank, I would concur that yes, hard acceleration MAY have some issues arise, but you are asking with 1/4 of a tank, or 4.5 gallons remaining.
IF this was a B Body car, (Impala SS, Roadmaster Fleetwood) the tanks are mounted flat like a pancake on the car. If you were running s/c on this car, I would have concerns about running with a low tank. I never took my SS out to the track with less than half a tank, given their history with pumps.


Just my .02, I'm rambling now.....

[BillyGman]

I think that Wes had made a very good point. Since the gas tanks in our Marauders are standing up verticle instead of laying down as it is with most other cars, it isn't an issue, since there isn't anywhere for the fuel to slosh away from the pump. I've raced my Marauder with less than 1/8th of a tank, and even close to being on "E" on the dragstrip, and turning 1.6 second 60' times at that. And I've never had any problems. In fact, I can honestly say that atleast 4 passes that I've made on the dragstrip where my Marauder turned 12.0's and 12.2 second ET's, were done while there was literally only 2 to 3 gallons of gasoline in the tank.

Let me point out, that I fully agree that using a 1/4 tank of gas while racing your Marauder, is a good practice. However, going full throttle from 60-100 MPH on the highway with 1/8th tank of gas in a Marauder is no biggie. I do that on a routine basis with my Trilogy equipped Marauder, and after 41,000 miles, the car still runs great, and can walk away from Camaros and Vettes.

[martyo]

I think that Wes had made a very good point. Since the gas tanks in our Marauders are standing up verticle instead of laying down as it is with most other cars, it isn't an issue, since there isn't anywhere for the fuel to slosh away from the pump. I've raced my Marauder with less than 1/8th of a tank, and even close to being on "E" on the dragstrip, and turning 1.6 second 60' times at that. And I've never had any problems. In fact, I can honestly say that atleast 4 passes that I've made on the dragstrip where my Marauder turned 12.0's and 12.2 second ET's, were done while there was literally only 2 to 3 gallons of gasoline in the tank.

Let me point out, that I fully agree that using a 1/4 tank of gas while racing your Marauder, is a good practice. However, going full throttle from 60-100 MPH on the highway with 1/8th tank of gas in a Marauder is no biggie. I do that on a routine basis with my Trilogy equipped Marauder, and after 41,000 miles, the car still runs great, and can walk away from Camaros and Vettes.

Billy: Stop wasting your time posting here and hurrry up and finish my bad ass Chebelle!! :D

[SergntMac]

Ummm...I'm wondering...If there's only 2-3 gallons of fuel in the tank, how much of that fuel is inside the baffle with the pick up tube? Maybe a pint? Quart?

[MarauderMark]

Ummm...I'm wondering...If there's only 2-3 gallons of fuel in the tank, how much of that fuel is inside the baffle with the pick up tube? Maybe a pint? Quart?
Can twin focus fuel pumps suck it dry before it gets down the 1/4 mile?

[SergntMac]

Yes. That's exactly what I said ^ there.

It's not about sloshing, '60 times, or, even top end. It's about how fast your fuel system can empty the baffle can.

If you're going to have this problem, most likely it will surface in the second 1/8 mile, and at very high RPMs, like top of 3rd gear? Suddenly shut off the fuel supply at 6000 RPM, it goes bang...

[Jerry Barnes]

I run my cars at the track with only an 1/8 of a tank. I have never had a problem. But, my F150 supercharged or not, shuts off because of lack of fuel delivery. The tank design is not very good on the F150.

Jerry

[SergntMac]

More 411...

http://www.modularfords.com/forums/2003-2004-mustang-cobra/summary-of-blown-engines-12489.html

[BillyGman]

Billy: Stop wasting your time posting here and hurrry up and finish my bad ass Chebelle!! :DI'm working on it Marty. But this is a scary weekend for me..... our union contract at Sikorsky is up for renewal, and the company wants to cut back on our benefits despite their fantastic profits, so tomorrow we will be voting on weather or not to strike!!! So I might be on the picket line on Monday, and if that happens, it's going to delay project Chevelle. :alone:

BTW, I've made several runs down the 1320 with merely a few gallons of gas in the Marauder gas tank with the Trilogy S/Cer installed, which resulted in a 114 MPH trap speed in 3rd gear, and that's with 4.56 gears. So there's just no way that there was a lack of fuel supply. With other cars there might have been if they had the tank that's mounted laying down, but since the Marauder tank isn't mounted that way, it's a whole different story. if you're leaning out at high RPM's with your Marauder, then that's the engine tuner's fault. Not the gas tank.

[rayjay]

I'm working on it Marty. But this is a scary weekend for me..... our union contract at Sikorsky is up for renewal, and the company wants to cut back on our benefits despite their fantastic profits, so tomorrow we will be voting on weather or not to strike!!! So I might be on the picket line on Monday, and if that happens, it's going to delay project Chevelle. :alone:

Off subject post here: but at least you can strike, 3 yrs, no contract :mad:

[Tallboy]

I'm working on it Marty. But this is a scary weekend for me..... our union contract at Sikorsky is up for renewal, and the company wants to cut back on our benefits despite their fantastic profits, so tomorrow we will be voting on weather or not to strike!!! So I might be on the picket line on Monday, and if that happens, it's going to delay project Chevelle. :alone:

Fingers crossed for you and my dozen family members who work with you.

[BillyGman]

Off subject post here: but at least you can strike, 3 yrs, no contract :mad:But atleast you have work, and therefore a paycheck coming in. And if you haven't a contract, doesn't that mean that you've been reverted back to the conditions and benefits of your old contract? That would be fine for us, because we're not demanding anything additional. We just don't want benefits that we've had for decades to be taken away from us. particularly since the CEO and big execs are rolling in the cash from BIG profits that they obtain from our work. This predicament is all due to the typical American corporate greed, as well as lack of regard for the worker bees and nothing more.

[BillyGman]

Fingers crossed for you and my dozen family members who work with you. Thanks. We will know for sure on Monday morning. Didn't mean to hijack this thread, but this is just the top thing on my mind right now, and it looks to me like Mark has already got all the answers he needs in this thread anyway. It's all been said, and anything more will undoubtedly turn into needless arguments. (no offense Mark)

[MarauderMark]

Thanks. We will know for sure on Monday morning. Didn't mean to hijack this thread, but this is just the top thing on my mind right now, and it looks to me like Mark has already got all the answers he needs in this thread anyway. It's all been said, and anything more will undoubtedly turn into needless arguments. (no offense Mark)
Billy you hit the nail right on the head er , fuel delivery situation :D buddy.But i hope everything works out for you and your co-workers.
BTW-I never get offended on highjacked threads any kind of conversation is great:up:whatever it may be.:D

[BillyGman]

i hope everything works out for you and your co-workers.
BTW-I never get offended on highjacked threads any kind of conversation is great:up:whatever it may be.:D Thanks Mark. Tomorrow is the big day of the union contract vote. I'll be on pins and needles until then. :depress:

[SergntMac]

Didn't mean to hijack this thread, but this is just the top thing on my mind right now, and it looks to me like Mark has already got all the answers he needs in this thread anyway. It's all been said, and anything more will undoubtedly turn into needless arguments. Indeed. There is sufficient data and testimony on the table to aid folks in drawing their own conclusions. Thank you for your participation as well, and good luck on the union issues. I just settled my contract after 3 years in binding arbitration, can't wait to see the retro check.

The one thing I don't get, is why someone would risk their engine for the sake of a few gallons of fuel. The weight savings just don't justify the risk, IMHO. Just my .02C, carry on gents.

[MarauderMark]

The one thing I don't get, is why someone would risk their engine for the sake of a few gallons of fuel. The weight savings just don't justify the risk, IMHO. Just my .02C, carry on gents.
I;ll never do that again. i read threads that said some use less than a 1/4 tank and i was at 1/3 .whatever i never went under 1/4 but i do understand now NEVER go under 1/2.What a costly/stupid lesson to learn..:mad:

[Joe Walsh]

I'm working on it Marty. But this is a scary weekend for me..... our union contract at Sikorsky is up for renewal, and the company wants to cut back on our benefits despite their fantastic profits, so tomorrow we will be voting on weather or not to strike!!! So I might be on the picket line on Monday, and if that happens, it's going to delay project Chevelle. :alone:



Hey Billy, Why don't you put a REAL engine....a Helicopter turbine in your Chevelle and sell me that 'wimpy' 632??:D

BTW: Good luck with the contract vote.

[rayjay]

Indeed. There is sufficient data and testimony on the table to aid folks in drawing their own conclusions. Thank you for your participation as well, and good luck on the union issues. I just settled my contract after 3 years in binding arbitration, can't wait to see the retro check.

The one thing I don't get, is why someone would risk their engine for the sake of a few gallons of fuel. The weight savings just don't justify the risk, IMHO. Just my .02C, carry on gents.

ditto here on the binding arb process, still several months out. The sock filter on the fuel pump was a real issue on 00-01 Focus. Letting the tank run too low would ruin the sock and hence the pump. Ford was finally pushed into a recall by the NHTSA as it became a safety hazard with the engines shutting down on expressway on ramps.

[BillyGman]

We're going to strike!!! I can't believe that my bonehead co-workers voted like that!!! :mad2: Voting in favor of the contract offer would've meant a $2,000 signing bonus for each employee, and only an $8 per week increase in medical costs for single folks, and a $16 per week increase for married people!!

But instead all the sheep did what our crooked union told them to do, and rejected the offer. And now we will be losing a lot more than just the medical cost increase, each week that we're out of work. Sometimes I hate unions!!!! Who's gonna pay my mortgage??? The union won't. And whenever we do go back to work, the union will still undoubtedly take their back dues out of our paychecks!!!!! I could break the picket line, but that can get ugly because of the blind faith that some have to the corrupt union we have!! And even when I get through the line, I'll have to worry about what's happening to my car out in the parking lot for the entire 8 hours I'm in work. :shake:

Well anyway, needless to say, project Chevelle is on hold now. :down: I hope that we go back to work soon, but this just isn't looking too good.

[rayjay]

Hopefully it will be short and resolved for the best. You sometimes have to draw a line in the sand.

[GreekGod]

I'm surprised no one mentioned that gasoline cools the pump! Pumps are known to overheat and/or lose service life from running low on "coolant".

A high output/performance pump should draw even more current than a stock pump and run even hotter.

The tank is in an excellent location to aid 60' traction. That's why batteries are located to the right side of the trunk.