1/4 mile confusion

[muslhed]

I went to the track in Hallsville Texas this past weekend, and I made 8 passes down the 1320. My very first pass, I ran a 14.61@96.70. This turned out to be the fastest time of the day. Here's where I begin getting concerned. Every run I made after that was progressively slower, all the way to a worst time of 15.60!!! :confused: All passes were done with the overdrive off, and the shifter left in drive. My rear tire pressure was 25 psi, and my right foot was obviously on the floor the entire length of the track. I had no traction problems at all. I changed absolutely nothing about the car, nor my launch technique during all 8 passes. I had more than adequate cool down time during the first 5 passes, but the last 3 passes were one right after the other, and all of them were in the low to mid 15's. :depress:

Where's the consistency? My car has 3000 miles on the ticker, and the only mods are outlined in my sig. It seemed like it became more and more sluggish leaving the line each time until I reached about 3000 RPM in 1st gear. Then it began pulling.

Any suggestions or input would be greatly appreciated, because I'm still scratching my head!!

Jeremy

[Cobra25]

Sounds to me like you need a Dennis Reinhart stage 1 installed. Big difference!

[2003 MIB]

Any suggestions or input would be greatly appreciated, because I'm still scratching my head!!
That was a weird track day, Bro. My own woes were related to the left lane and an empty trunk. My best time that day was when I ran against you (me=right, you=left). I think the right lane was better. I think your transmission fluid was hot (more viscous) and that slowed you down. I'm no expert but that's my $.02.
Hey, you still want that grill?

[teamrope]

I'm just taking a guess here, but if the first run was in the morning before it started warming up, the air was cooler and more dense. Just from what I’ve seen on ESPN2, most NHRA records are set during the evening qualifying sessions when the air and track are cooler.
I'm not claiming this to be the case, just taking my best guess. It's the only variable I see changing.

[sailsmen]

Temperature and Humidity can affect times greatly.

Also how much fuel did you have in your tank?

Less than a 1/4 and you could have a fuel delivery problem.

[Ross]

Sailsmen, that's interesting about having less than 1/4 tank giving fuel delivery problems. I'm totally inexperienced at track racing, but I thought that you wanted to race with just a little fuel in the tank to reduce weight? I think I'm about to learn something...again.

[CRUZTAKER]

Your times will definately get worse as it gets warmer. If you are not icing or cooling the engine in between frequent runs, this is normal. I ran horrible times at Ennis, and it only got worse as the day went on ( 14.6+/-.3). My best time came after the car sat with the hood open for 5 hours, and it was nearly 10:30 in the evening. The temp guage had barely rose from it's resting place when I ran a 14.2.

As far as your times in general, they're good! If you want better, ease into some stage I mods. The chip will definately knock the numbers down.

Heat is your worst enemy. Invest in a large ice cooler, and bring 20 bags of ice if you are really serious about racing in the heat of the Republic.

Good luck man....

EDIT: I forgot to mention, your car is young, it's still learning. Right around 7500 miles things start to change. It's kinda like puberty for an automobile.

[Smokie]

I went to the track in Hallsville Texas this past weekend, and I made 8 passes down the 1320. My very first pass, I ran a 14.61@96.70. This turned out to be the fastest time of the day. Here's where I begin getting concerned. Every run I made after that was progressively slower, all the way to a worst time of 15.60!!! :confused: All passes were done with the overdrive off, and the shifter left in drive. My rear tire pressure was 25 psi, and my right foot was obviously on the floor the entire length of the track. I had no traction problems at all. I changed absolutely nothing about the car, nor my launch technique during all 8 passes. I had more than adequate cool down time during the first 5 passes, but the last 3 passes were one right after the other, and all of them were in the low to mid 15's. :depress:

Where's the consistency? My car has 3000 miles on the ticker, and the only mods are outlined in my sig. It seemed like it became more and more sluggish leaving the line each time until I reached about 3000 RPM in 1st gear. Then it began pulling.

Any suggestions or input would be greatly appreciated, because I'm still scratching my head!!

Jeremy
I been thinking a great deal about your results and the 1 second spread between best and worse and your use of the word sluggish leaving the line and also your mileage.

Two things come to mind, your car has not peaked mileage wise yet, mine took about 5k. Next my car's shifting was very, very sluggish from a dead start until Dennis reflashed my PCM. I strongly recommend what Dennis does to PCM, sluggishness will cease to exist.:up:

The time in my sig. was done on a sunny day in Fla. temperature at time of run about 63*. reflash is all I have done.

[sailsmen]

It has been observed that with less than a 1/4 tank the fuel in the MM can slosh to the rear of the tank outside the p/u basket resulting in a lean condition.

It appears the fuel delivery on the MM is marginal. There are some fixes available, such as Cobra fuel pumps and larger fuel filter.

[muslhed]

Wow, that's some awesome observations! Alright, I had 3/4 tank of gas, and my first & best run was at noon. It probably wasn't any hotter than 65-70* that day. The day just got cooler from there. It really didn't seem that humid, but I may just feel that way because I'm used to it. Dan's Marauder had trouble hooking up on the track, as did most everyone that day, but mine didn't even try to spin the tires upon launch. Shoot, even my wife's turbo VW GTI had major issues trying to hook up...even with the factory front locker engaged!
So, I don't know. Would going ahead and installing a new chip get me past the factory computer trying to learn? Or would it do that anyway until I hit a certain mileage mark?

[muslhed]

That was a weird track day, Bro. My own woes were related to the left lane and an empty trunk. My best time that day was when I ran against you (me=right, you=left). I think the right lane was better. I think your transmission fluid was hot (more viscous) and that slowed you down. I'm no expert but that's my $.02.
Hey, you still want that grill?

I PM'd you on the grill! Yes, I certainly do want it, but my trip to Dallas got postponed, and I've been driving all of my sales teams month end sales figures this week. busy~busy~busy!!!!

Anyway, You may be on to something there about the tranny fluid, and that actually makes a lot of sense. I may get a big tranny cooler mounted up front with an additional electric fan to keep it cool. Might even be a good excuse to go ahead and get a tranny temp gauge!

Jeremy

[CRUZTAKER]

Your car will definately start to act different in short time whether you do a chip or not.

A chip install however will give you instant results, on top of the car growing with age. That's why many folks don't mod until the car passes this so called puberty.

I was impatiant, and didn't listen to the growth analogy. None the less, at 12,000 miles, I couldn't be more happy. The car will still surprise occationally with a new trick.

[JET]

had trouble hooking up on the track, as did most everyone that day, but mine didn't even try to spin the tires upon launch. Shoot, even my wife's turbo VW GTI had major issues trying to hook up...even with the factory front locker engaged!

If everyone had a traction problem except you then you're not getting enough torque to the rear wheels. You need to power brake at the tree. Despite that your times are great for the level of mods you have.

[sailsmen]

I have reviewed my time slips and I ran 3 10ths differnce and only 7-8 minutes apart.

On another occasion 4 10ths differenc and 15 minuts apart.

All the differences greater than 1 10 th were due to different launch teachniques.

Seems like your range is very large.

Double check oyur time slip, do you have the correct lane for the time.

[Mattsmerc]

I have just made a couple of runs with my g-tech. My best time was 15.59@95.3. Temp tonight was a cool 68 degrees with no mods at all. Maybe my time will be better at the track? And the mods would be nice too!! Faster is better, :confused: if only my wife would understand that :confused:

[cruzer]

I PM'd you on the grill! Yes, I certainly do want it, but my trip to Dallas got postponed, and I've been driving all of my sales teams month end sales figures this week. busy~busy~busy!!!!

Anyway, You may be on to something there about the tranny fluid, and that actually makes a lot of sense. I may get a big tranny cooler mounted up front with an additional electric fan to keep it cool. Might even be a good excuse to go ahead and get a tranny temp gauge!

Jeremy
Jeremy, just an observation--I ran Hallsville in Dec with one run at 96.87--I have a DR flash only. when I got home , I checked the tranny fluid--it was discolored--had the pan dropped and inspected it in bright sunlight--no metal--replaced filter, flushed and filled--tranny smoother and have no trouble chirping on dry pavement-- the DR flash really makes a lot of difference in smoothness of tranny. maury

[2003 MIB]

I think I'm about to learn something...again.
Well Ross, you've inspired me to tell the whole ugly story- here goes:
I was at Hallsville with the rest of this motely crew. I followed your same logic path that a car that weighs less would be faster. I also figured that less than a quarter of a tank could cause some sloshing that could starve the fuel pump on hard acceleration (read it on the site). I also had read about the futility of burnouts on street tires. So:
First run was done with no spare tire, no trunk organizer and (ahem) no CD cartridge in the changer. Just under half a tank of 93 octance Exxon. Tire pressure reduced to 25 psi in the rear. 30 mitues of cool down time while I B/S'd with the guys and waited for the track to open. I had high hopes that the addition of underdrives would easily best my personal record of 14.243.
I go to stage, driving around the waterbox and when the lights hit, I did a "kid leaving the Dairy Queen" smoke show that probably killed every bug in East Texas. I got off it and turned a 20.74...
After four more runs, nothing below 14.7 I returned to the proven model. My last run of the day was with Muslhed- I put all my crap back in the trunk. Did the burnout. That run was 14.262. I'll be faster next time out in Rusk.
I think the logic of lighter is faster is true but there's also a truism in that it matters where the weight is located in drag racing.
I'm not proud of my skills or brainpower that day but if it saves somebody else from going slow that's cool with me. The point of these track days (at least why I'm there) is to have fun and catch up with the other folks about their cars, kids, life etc... Hell, Jim showed up in a rented beige Chevy while his Marauder is being "worked".
DISCLAIMER: I'm no expert, my first track run ever was the day after I met you and Dawn in Ennis.
-Dan

[BillyGman]

I agree that the reason for your car getting slower and slower as the day progressed was most likely due to the air temperature getting warmer. Especially if you're in Texas. What was the temperature at the track anyway?

However, I find this whole theory which seems to be popular on this board about having less than 1/4 tank of gas being a problem. I say that because my best times at the track last year were run on almost empty. I literally had about 2 gallons of gas in the car and that's when I ran 13.5 sec 6 times in that same day. Even if you did get the much talked about gasoline "slosh" in the gas tank, there's enough gasoline in the gas line alone to get you through the 1/4 mile. Therefore your fuel pump is still going to deliver enough gas to the fuel injectors to get you through the race.

[2003 MIB]

Billy-

Call it 65-70 degrees F while we were there (noon to 5:00pm). Your stuff about the fuel issue makes a lot of sense...Thanks!

[sailsmen]

Wether or not the MM has a potentially lean condition with less than a 1/4 tank is unknown to me. It has been reported by others to be so.

I believe several members have on order an afr sensor that they will be getting data from while they are operating the vehicle. Perhaps they can report their findings.

I do know that a lean condition can quickly result in a blown engine. The Mustangs, Fast Fords' Lightening blew it's engine on a 1/4 run. They then had the engine built by a Lightening Specialist. On the dyno it showed a lean condition caused by a faulty fuel pump relay. It was determined this was the cause of blowing up the engine.

To be safe I fill her up when the needle gets to a 1/4 and run her at the track with 1/2 tank.

[Ross]

Wow, this is news to me. I must have missed the threads on this low gas/lean fuel mixture condition. I usually run my tank down to almost empty before I fill up.

[TripleTransAm]

I think it was a function of increased ignition retarding as the engine temps increased in combination with warmer intake air. One of the things that stood out the most in my mind when I compare my summer runs and my fall runs was the complete change in attitude below 3500 RPM. In the summer warm runs, I remember noting in my thread how the car really needed some 'go' below 3500 if I was to improve on my 15.06 ET. In contrast, my fall runs felt like an explosion below 3500... a MUCH stronger low end performance, enough to net me my 14.56 ET with nothing else changed, except a dirtier air filter (and a replaced driver's cylinder head).

[BillyGman]

I'm sure that if anyone has a lean condition in their engine, then it's due to computer error, injector malfunction, incorrect chip, clogged fuel line, etc.,etc.,etc..........my theory is that if it was due to gasoline "slosh" in the tank, then the engine would simply cutout, or perhaps even hesistate. But I can't see your engine running lean through a 1/4 mile run and causing engine failure simply because of the tank level being near empty. Like I've stated in my previous post, even if you did have such a thing as fuel "slosh" in the tank, it would merely happen when the "G"-force is at it's greatest at the first 60 feet of the run which lasts only two seconds tops, and would NOT even effect the amount of gas getting to the injectors since you alreay have more than enough fuel in the fuel line to take care of the entire 1/4 mile run anyway.

Remember that a gasoline engine doesn't burn pure gasalone as fuel, but rather a mist of it that's actually a ratio of air and gasoline(about 14 times mre air than gasoline: AKA 14:1 Air Fuel Ratio). And also the fuel line is quite long on a front engine car since the gas tank is in the rear.

Furthermore, the gas tank on the Marauder is standing up in a verticle position instead of laying down. So I doubt that there would even be any fuel "slosh" anyway.

[2003 MIB]

Wow, this is news to me. I must have missed the threads on this low gas/lean fuel mixture condition. I usually run my tank down to almost empty before I fill up.

I never go below 1/4 of a tank in any fuel injected vehicle if I can help it. I've always been told that you suck trash and filter clogging sediment if you run the tank low. Might be a myth but that's what I do.

[BillyGman]

I never go below 1/4 of a tank in any fuel injected vehicle if I can help it. I've always been told that you suck trash and filter clogging sediment if you run the tank low. Might be a myth but that's what I do.

Yeah, I've heard that's the case too, but w/old cars that have metal tanks that begin to rust after many years. Our Marauders have plastic gas tanks though.

[SergntMac]

I'm sure that if anyone has a lean condition in their engine, then it's due to computer error, injector malfunction, incorrect chip, clogged fuel line, etc.,etc.,etc..........my theory is that if it was due to gasoline "slosh" in the tank, then the engine would simply cutout, or perhaps even hesistate. But I can't see your engine running lean through a 1/4 mile run and causing engine failure simply because of the tank level being near empty.
It's a real problem okay, more for supercharged cars than N/A. In the high RPMs, the stock fuel pump pressures fall insufficient, and the comuter pulls timing, but not spark. This happen on the track, not on the dyno, which indicates a bottle neck in the fuel system. It may well indeed be happening on N/A cars, buy you may not be noticing it in the brief time you are racing.

When you pull timing at 5K RPM, but not spark...boost leads to boom. There's a dozen broke engines out here all tracing back to fuel pumps. Kenny Brown knew this two years ago when he installed a Walbro 255 in the #1x car, and it's also why Reinhart's supercharger kit comes with dual Cobra fuel pumps. I am sure if you paid close attention in the upper RPMs, you will notice it, or, record your runs on a Car Chip EX and read the data?

[Ross]

So would a bigger fuel pump/fuel filter combo be a good idea for a lot of us? What would be the cost of a decent combo like this? Is it something that an average wrench can do at home?

[BillyGman]

HMMMMMM, not sure what you mean MAC when you say "pull timing, but not spark"........I know that you're speaking of the timing being retarded momentarily, but I don't know what your reference to "spark" means.

However, whatever the case is w/the terminology confusion, either way, w/a S/C'd engine, it only makes sense to me that you would need a fuel pump that delivers a higher output of fuel in order to avoid a lean condition since the addition of a S/Cer enables the engine to draw a higher volume of air into the cylinders. Ofcourse w/more air going into the cylinders, you also need more fuel going into them too. Otherwise, THAT would cause a "lean" condition (AKA too much air, and not enough fuel).

Frankly, I'm surprised to hear that there are certain companies who are NOT including a higher output fuel pump AS WELL AS bigger fuel injectors w/their Supercharger kits. I'd think the addition of those things would be standard. No?

The bottom line though is that w/a S/C'd engine, the most likely cause of a lean condition is going to be an indadequate fuel delivery system (fuel pump, and injectors) rather then gas tank "slosh". Especially if you're using the facory stock fuel pump and injectors on a car that does NOT come from the factory w/a Supercharger. Don't you agree MAC?

On the more potent Nitrous Oxide engine kits, a higher output fuel pump IS included along w/bigger injectors since NO2 is a oxygen laden fuel,and therefore creates a need for more gasoline going into the engine JUST AS a Supercharger does.

[muslhed]

When I made those runs last Saturday, I used the same launch technique every time. First, I did a decent burnout to clean the tires off, and get them a little sticky. After I staged, I held the brakes firmly with my left foot, while bringing my RPM's up to 1000 RPM and held it there until the 3rd light came on. Then I released the brake, and instantly give her the full hammer.
As far as the temperature getting hotter as the evening progressed...it just seemed like it got cooler, not hotter. Like I said before, maybe I'm just used to it.
The car just seemed like it got more and more sluggish when leaving the line each time. I can only see one possible reason why it would have gotten so much slower with each run. First I feel like the tranny temp may have played a big role in each run. Maybe I got a little too over zealous with my burnouts. It seems like that could have caused a BIG increase in tranny temps right before I made a timed run. Sounds logical to me. Next time, I'll go much easier at the burnout box, to see how that affects my consistency. I'll probably also get a big tranny cooler (maybe B&M's cooler and fan combo) installed before I run it again. We'll see what happens!

Jeremy

[sailsmen]

Popular Hot Rod had a 3 time NHRA champ to give tips. He said gas powered cars are affected the most by humidity over temp or altitude.

Did the humidity rise during the day. I just don't think it was the tranny temp with the time between runs. If it were the tranny temp it owuld have probably showed up on other MM that have run at the track.

[BillyGman]

hmmm, i wonder if it can have something to do w/the stock torque converter heating up. I say that simply because when I ran my car 8 times at the track one day, it remained consistent w/the ET's, but I do happen to have an aftermarket torque converter.

[TripleTransAm]

I ran consistent 14.6s all night long during my fall blitz, with that one magical 14.56. While it was a cool night, the same kind of blitz but on a summer afternoon some months earlier saw a bunch of 15.2s and 15.1s with one dip into 15.06 . I honestly never considered a hot torque converter soaking up any power, but it's an interesting proposition to consider... how would you see this situation coming about?

Sarge is right about the sc / NOS and their sensitivity to a/f ratios. I'm not sure a pure stocker would see any damage... any increased cylinder temp from leanness would result in pinging which would result in timing being pulled, but s/c or NOS cars would see a tremendous imbalance in air quantity... VERY cooked cylinders to be sure. (I'm with BillyGman, though, in saying I too am not clear what is meant by "pulling timing but not spark").


EDIT: forget that 15.06 reference... it was 15.096. Damned brain...

[junehhan]

I envy your times, because I was unable to turn anywhere near the times you got at the dragstrip today :depress:

[BillyGman]

TTA, as for the Torque converter possibly heating up, it was merely a speculative question that I was posing. I don't even know if that is possible, nor if that can even be a factor. The only reason why I brought that up is because of the fact that I've experienced consistency among the ET's that I've obtained, whereas Muslehed didn't. And he has a stock converter, and I do not. So weather that's merely coincidental or not, I don't really know. It was just a hunch.

thanks for your input.

[TripleTransAm]

Junehhan, just as in Real Estate, it's all about break-in, break-in and break-in (yeah, I know the saying actually goes "location, location, location" but I figured I'd get all our LEOs on the board all worked up! ;) ).

Billy, I gave that torque converter thing some more thought... could tranny fluid change viscosity with temperature and affect the transfer of fluid (and torque) from impeller to turbine? Can anyone shoot this down? My head hurts... (spent the WHOLE day at emergency wards (yes wards) with my young son, suffering from a bonafide pneumonia...)

[junehhan]

Junehhan, just as in Real Estate, it's all about break-in, break-in and break-in (yeah, I know the saying actually goes "location, location, location" but I figured I'd get all our LEOs on the board all worked up! ;) ).

Billy, I gave that torque converter thing some more thought... could tranny fluid change viscosity with temperature and affect the transfer of fluid (and torque) from impeller to turbine? Can anyone shoot this down? My head hurts... (spent the WHOLE day at emergency wards (yes wards) with my young son, suffering from a bonafide pneumonia...)


Steve, i've got 5500 miles on my Marauder now, so I think the break-in period should be over, right? It was just shocking, especially that first run I made.............

[junehhan]

Steve, did your son get this latest strain of the cold virus that is floating around lately? It has caused a lot of my coworker's to also get pnemonia, along with a few members of the faculty at the college of Nursing here at the University of Cincinnati.

[MM03MOK]

My head hurts... (spent the WHOLE day at emergency wards (yes wards) with my young son, suffering from a bonafide pneumonia...)I hope Victor feels better very soon - and you too.

[TripleTransAm]

I hope Victor gets better very soon - and you too.

Thanks. Still got an uphill battle for the next few days, hope he can keep up his oxygen saturation to avoid a hospital stay. The next 48 hours will be crucial. As for me, well who cares... I wish I could be the one suffering through this instead of him. :(

Junehhan, I have heard of a pretty bad strain of flu/cold virus going around... while EVERYONE around him is in good health, he seems to have somehow gotten nailed by this. I suspect it was a visit to a crowded shopping center last weekend. Moron that I am, I've learned my lesson... might be a good thing to limit contact with large crowds during the peak weeks of the flu season.

Back to the subject matter... there's no telling what they did to the Marauder's programming for 2004. Rumours used to fly about regarding a possible "mileage-based limiter" on the early LS1s such as on my 1998, which would 'unlock' once past a certain pre-set mileage point.

Do you have any valvetrain noise? (ie. ticking at idle, or the clattering at off-idle due to inaccurate torquing of the cam holddowns?). If so, with 2 knock sensors the PCM may be picking up false knock due to that top-end rattle. Check for any rattling components which may falsely trigger a knock-based spark retard. This is a real potential problem that has happened before... the few LT4 F-bodies and Corvettes produced in 1996 and 1997 required a specific knock sensor module than their LT1 counterparts, due to a noisier valvetrain!

[BillyGman]

TTA, I hope your son gets better. I had that twice,and it's no picnic. As for the torque converter thing, maybe someone else will jump in here to answer that. I don't really know. All is I DO know is that this Stallion Torque converter (w/3000RPM stall speed) has made the biggest single ET reduction out of anything else that I've done to the car (.70 sec reducton) and as you can see by looking at my post signature, I've done a number of mods to my car.

So my thinking is, that maybe if this converter made such a difference in my ET's at the track, then maybe it's also better for obtaining ET consistency also. Again, this is merely a guess on my part.

[mrjones]

I went to the track in Hallsville Texas this past weekend, and I made 8 passes down the 1320. My very first pass, I ran a 14.61@96.70. This turned out to be the fastest time of the day. Here's where I begin getting concerned. Every run I made after that was progressively slower, all the way to a worst time of 15.60!!! :confused:


JeremySee, now I don't feel so bad. Your 3 slowest passes were made with me (beat me all 3 times, dagnabit), and I thought you were just taking it easy on me for my load of baby stuff I was carrying in the car. Now I feel better! I wanna try it again, this time with some 93 in the tank. When are we going again? In fact, when are some of you guys gonna come down to the new track in Lufkin? Check it out at http://www.pinevalleyracing.com/index.html

[Paul T. Casey]

Steve, Hope your son is feeling better as you read this, children do have a wayof aging us though.
Junehhan, if you're at 5,500 miles, then in my opinion, your car is only "half broke in." My "magic number" for break in seemed to be more like 10,000 miles. I don't know why, but it kept getting better with miles.
muslhed, I tend to believe that you too were spinning tire, especially if everyone else was. My day at the track I thought that I wasn't, but a close look and listen to the videos my wife shot showed me that I was indeed getting bitten by the traction-loss bug. I don't know about you, but I kind of got caught up in all the excitment and maybe shut down any "rational" senses while I was driving! :bounce:

[muslhed]

See, now I don't feel so bad. Your 3 slowest passes were made with me (beat me all 3 times, dagnabit), and I thought you were just taking it easy on me for my load of baby stuff I was carrying in the car. Now I feel better! I wanna try it again, this time with some 93 in the tank. When are we going again? In fact, when are some of you guys gonna come down to the new track in Lufkin? Check it out at http://www.pinevalleyracing.com/index.html

I'd love to come check out the new track anytime! I'll be back in town the 3rd week in March, so any weekend after that sounds good! Take it easy man!

Jeremy