Best 1/4 mile ET's 2wd or 4wd? what would you build on?

Do you think the added traction of leaving the line in 4 wheel drive would improve ET's? I know 2wd models are considerably lighter, but wouldn't the added traction of 4wd compensate somewhat for the extra weight? If you were going to build a turbo'ed stroker to beat on at the strip, using an XJ/MJ what would your ideal platform be? 2dr XJ with lexan windows for more rigid chassis? Or long wheel base MJ, for lightest weight and best weight transfer? What would you build and why? Keeping in mind that this is mostly inspired by having several "parts cars" sitting around useless.

Personally I think a long wheel base MJ (long bed), totally gutted, with a four bar 8.25 rear, stroked 4.0 with a JY T3 T4 Hybrid Turbo would probably surprise the crap out of some built SBC's and SBF's The MJ is already exremely light, with 4wd the super light rear wouldn't pose as much of a traction problem. On the other hand an NP231 is somewhere around 66 pounds dry, add the live 30 in front and the drive shaft and it's got to be 300 pounds heavier..

Anyone know what the weight difference is between 2 and 4wd MJ's?

I went to the track last summer on a nice and toasty day in my 98 cherokee 4x4 4.0 maybe 90k miles at the time, as well as a toasted electrical fan...ran low 17's with 4wd but obviously no slipping at start and mid to high 16's with some spinning in 2wd. If i had anywhere near decent tires I could be able to grip and maybe get low 16's. And maybe if it wasnt so damn hot and I could cool down my engine better and not let it suck all that hot air into my rustys intake, maybe. Just maybe i could have squeezed high 15's. Anyways...you'd prolly need 4wd if you have over 200hp at the engine with 235's, just a broad guestimate because thats what it took for me. Also, when at the dyno last fall we found ~30% loss with 4wd and ~20% loss with 2wd. What I did on some runs was powerbrake with 4wd, then take it out between the 1-2 shift by letting off that gas so it disengages.

Tracks opening up soon, might go for a drive out there prolly to spectate, however im contemplating running it again if its cold enough after I fix all that i need to get done.

1bolt said:

Do you think the added traction of leaving the line in 4 wheel drive would improve ET's? I know 2wd models are considerably lighter, but wouldn't the added traction of 4wd compensate somewhat for the extra weight? If you were going to build a turbo'ed stroker to beat on at the strip, using an XJ/MJ what would your ideal platform be? 2dr XJ with lexan windows for more rigid chassis? Or long wheel base MJ, for lightest weight and best weight transfer? What would you build and why? Keeping in mind that this is mostly inspired by having several "parts cars" sitting around useless.

Personally I think a long wheel base MJ (long bed), totally gutted, with a four bar 8.25 rear, stroked 4.0 with a JY T3 T4 Hybrid Turbo would probably surprise the crap out of some built SBC's and SBF's The MJ is already exremely light, with 4wd the super light rear wouldn't pose as much of a traction problem. On the other hand an NP231 is somewhere around 66 pounds dry, add the live 30 in front and the drive shaft and it's got to be 300 pounds heavier..

Anyone know what the weight difference is between 2 and 4wd MJ's?

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For a 1/4 mile Drag Truck or any drag racing vehicle you need to draw a imaginary line between the highest point of the body and and the center of the front axle.

Every thing that you can lighten up above that line will give you better traction and .....if you have a traction problem, adding weight to back bumper (like a 150 pound bumper) will make you go quicker in a 1/4 mile even tho you jeep is now 150 pound heaver!

With a 4 link (properly set up) you will never need 4WD and will always get the best E.T it 2WD.

EXCEPTION to the rule: if you frying one tire of the line.......4wd would help get ya off the line much better and there for a quicker E.T.

If you have really tall gears, or big tires and are racing at a 1/8 mile track 4LO WOULD BE YOU BEST FRIEND!:thumbup:

Real good sticky tire with the front drive shaft remove would be a real kick in the pants to........on a 1/8 mile track!

OK done babbling

Flash.

Flash said:

If you have really tall gears, or big tires and are racing at a 1/8 mile track 4LO WOULD BE YOU BEST FRIEND!:thumbup:

Real good sticky tire with the front drive shaft remove would be a real kick in the pants to........on a 1/8 mile track!

OK done babbling

Flash.

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Has anyone ever tried that? I'll admit i tried it with my stock tired cherokee uphill because when you gun it, the engine speeds up too quick and then shifts quick. Maybe with 3.07 gears and tall tires it would work. If you took out the front driveshaft, you could still run 4LO without any problems? That'd be interesting to see. with a stock tired jeep top speed is around 60mph in top gear...

Well shucks my wheelchair can do that quarter mile in 10.07@127 miles an hour. I just burn em off in the water box a little bit before I go to get the dust from my hardwood floors inside my house off. I just put a wheelie bar on the back along with a spoiler.

If you compare a 4WD to a 2WD vehicle of equal weight and HP/TQ, the 4WD vehicle will have a lower 1/4 mile ET while the 2WD vehicle will have a higher 1/4 mile trap speed. The reason is that the 4WD will have better traction off the line but because it has a higher drivetrain HP/TQ loss, it puts less of that to the wheels hence the lower trap speed.

Lee at hesco has a MJ that will run 13.10......

Dr. Dyno said:

If you compare a 4WD to a 2WD vehicle of equal weight and HP/TQ, the 4WD vehicle will have a lower 1/4 mile ET while the 2WD vehicle will have a higher 1/4 mile trap speed. The reason is that the 4WD will have better traction off the line but because it has a higher drivetrain HP/TQ loss, it puts less of that to the wheels hence the lower trap speed.

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Not 100% true, if you've got a Jeep with 500hp and an open locker in the rear, you'll never get enough usable traction to get an ET less than that of a 4wd that can put it down (most likely) from the start. Yes you are correct that a 4wd has greater drivetrain loss and yes it has better traction off the line, but it isn't completely correct to say that it is because of only having more drivetrain loss. You're sending power to twice as many wheels in 4wd than you are in 2wd thus dispersing that power and allowing less to be able to break the wheels and lose traction. Granted after maybe 120 feet you shouldnt have to worry about traction as much (maybe if you have power going to 1 wheel and some scrawny 235), but Im pretty sure the more power in 2wd will be outweighed with the initial traction of 4wd. Think of an GSX (awd) vs GS-T (fwd) eclipse, yes rwd is much better than fwd at the strip due to the weight transfer but still. Dyno, you've got some calculators on your site that are pretty accurate, try it with a lot of power in rwd and then in 4wd and tell us what you get...

The XJ is a brick and 16's and 17's are nothing special, my old Tahoe went 16's stock too.

Those V8 Grand Cherokees like the 99's are pretty fast, I recall a friend running high 14's in his stock.

If the MJ is lighter, that's what I would race in. My old 89 MJ 5spd 2wd truck with a CAI and muffler was somewhere in the low 15's.

BBeach said:

Not 100% true, if you've got a Jeep with 500hp and an open locker in the rear, you'll never get enough usable traction to get an ET less than that of a 4wd that can put it down (most likely) from the start. Yes you are correct that a 4wd has greater drivetrain loss and yes it has better traction off the line, but it isn't completely correct to say that it is because of only having more drivetrain loss. You're sending power to twice as many wheels in 4wd than you are in 2wd thus dispersing that power and allowing less to be able to break the wheels and lose traction. Granted after maybe 120 feet you shouldnt have to worry about traction as much (maybe if you have power going to 1 wheel and some scrawny 235), but Im pretty sure the more power in 2wd will be outweighed with the initial traction of 4wd. Think of an GSX (awd) vs GS-T (fwd) eclipse, yes rwd is much better than fwd at the strip due to the weight transfer but still. Dyno, you've got some calculators on your site that are pretty accurate, try it with a lot of power in rwd and then in 4wd and tell us what you get...

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I think you misunderstood. I wasn't implying that you'd get better traction off the line in 4WD because there's a higher drivetrain HP/TQ loss with less reaching the wheels. The reason for the better traction is the torque being split between four wheels instead of two.
Front wheel drive cars tend to have worse traction off the line because the weight transfers to the back during launch, and that's why these cars tend to have a longer ET than you'd expect but a better trap speed. FWD cars with manual transmissions may only have a drivetrain HP/TQ loss of 8-10%.

Dr. Dyno said:

I think you misunderstood. I wasn't implying that you'd get better traction off the line in 4WD because there's a higher drivetrain HP/TQ loss with less reaching the wheels. The reason for the better traction is the torque being split between four wheels instead of two.
Front wheel drive cars tend to have worse traction off the line because the weight transfers to the back during launch, and that's why these cars tend to have a longer ET than you'd expect but a better trap speed. FWD cars with manual transmissions may only have a drivetrain HP/TQ loss of 8-10%.

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Well if you read what you said, you said: "The reason is that the 4WD will have better traction off the line but because it has a higher drivetrain HP/TQ loss, it puts less of that to the wheels hence the lower trap speed." From reading that it makes it look exactly like as if you were saying it was due to the less wheel horsepower. Like I said in my response, if you've got a 500hp XJ you'll deff get a better elapsed time AND trap speed because you'll have the traction the entire time even though it has less power. I also said that if you had 200hp or so with a 235, then you should be better off in 2wd. I think it was merely the way you worded it, I know you know better Dr.

Pro Stock John said:

The XJ is a brick and 16's and 17's are nothing special, my old Tahoe went 16's stock too.

Those V8 Grand Cherokees like the 99's are pretty fast, I recall a friend running high 14's in his stock.

If the MJ is lighter, that's what I would race in. My old 89 MJ 5spd 2wd truck with a CAI and muffler was somewhere in the low 15's.

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Yeah I agree, its sad and thats why I care less and less everyday about performance. If its fun and cheap, then whatever. Im pretty sure if I had the money to regear, get an LSD, 280-300hp stroker, etc. Then Id run low 14's...but is it really worth it when you can just get a rustang gt or a V8 camaro? Some say yes, and sometimes I do too because people see it as a slow jeep.

It would depend on what things the truck would be used for, if it was a track vehicle that is also streetable, I'd look at doing a Gasser style 2wd XJ or MJ. If I was going for something that wouldn't stand out as a hot rod and/or be used as a "jack of all trades" type vehicle, I'd go for something like this

with a stroker (maybe built only to run E-85 too), paddle shift AW4, 242AMG (HUMVEE version), and a good limited slip while using 15x8 Canyons and 255/60/15 street tires. The 242 should allow for a fairly quiet, high traction launch and well, who'd expect a Briarwoody to go ballistic. My sister walked a Vette last summer with this one. She got a good jump when the light changed and the Vette didn't catcher her until she backed out of it at around the speed limit. She got him so bad he actually slowed down to look at her Heep and when he realised is looked stock (since other than airshocks on the back, it is), he pulled up enough to cut her off then ran for it. She didn't even realise what she'd done to piss the guy off until her mother in law to be told her shortly there after "Good job pissing off the guy in the Vette!" (her fiance and his mom were following her in his Boreus...er..Taurus.)

BBeach said:

Yeah I agree, its sad and thats why I care less and less everyday about performance. If its fun and cheap, then whatever. Im pretty sure if I had the money to regear, get an LSD, 280-300hp stroker, etc. Then Id run low 14's...but is it really worth it when you can just get a rustang gt or a V8 camaro? Some say yes, and sometimes I do too because people see it as a slow jeep.

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I went as far as I could upgrading the performance of my Jeep without breaking the bank but I know that to take it to the next level, I'd have to budget over $5000 (forced induction, tranny/drivetrain/brake/suspension/chassis upgrades) and I just don't think it's worth it. I'm more than happy with my Jeep's performance and it's definitely fast enough to get me into trouble with the law (I drive carefully) so to satisfy my need for speed, I bought a Rustang GT and I'm modifying that instead. It has the looks and soon it'll have the speed to match. It's cost me just over $5000 for the purchase, repairs, and mods so far.
_____________________________
The sleeper: 1992 XJ Laredo - 4.6L Stroker - 5-speed manual
Dyno - 198hp@4650rpm, 254lbft@3550rpm (wheels) = 245hp@4800rpm, 306lbft@3550rpm (crank)
Performance - 0-60 = 6.2, 1/4 mile = [email protected] in full street trim
Sites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks

The sleeping: 1995 Mustang GT - 5.0L V8 - 4-speed auto
C&L 76mm MAF|Summit Racing 75mm TB|FRPP 1/2" manifold spacer, Gutted cats|2.5" mufflers, MSD cap/rotor|Taylor plug wires, EGR/AIR delete|Advanced timing, FRPP 3.73 r&p

It would be interesting to run in FT, locked, if you had the HP and/or gears. I can't say that I have ever had the XJ to the track, but did take a few passes on the 1/8th mile track with my full size Bronco. You really want some deep gears for the 1/8th--with 4.56 gears and 35" MTs, I was *just* hitting 3rd gear (B&M modded C6 auto w/ratchet shifter shifted manually) at the finish line @ 10 sec (70mph). With the Detroit, it did hook up pretty nice--I think 4.88 or 5:12 would have been better with the big tires.

bjoehandley said:

My sister walked a Vette last summer with this one. She got a good jump when the light changed and the Vette didn't catcher her until she backed out of it at around the speed limit.

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If thats a stock jeep, the speed limit must have been 25mph and the guy in the vette prolly wasnt even looking . :looney:

Speed limit should have been around 45mph on a 3 lane (each way) highway, and that Brairwood should be fairley light, and it pulls strong once it gets moving for a stock truck that's nearing 200k. The big thing was that she "cut a good light", and the truck was "in it's groove" buy the time Mr. Vette got moving. She also didn't know much other than it was a black and silver Corvette, which led me to wonder if it was one of the '78 Pace Cars specificly or just one of the pre LT1 C4's.

BBeach said:

Has anyone ever tried that? I'll admit i tried it with my stock tired cherokee uphill because when you gun it, the engine speeds up too quick and then shifts quick. Maybe with 3.07 gears and tall tires it would work. If you took out the front driveshaft, you could still run 4LO without any problems? That'd be interesting to see. with a stock tired jeep top speed is around 60mph in top gear...

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don't ya know, thats the secret, for stop light to stop light racing!(Not that i have ever done this! )4lo and front drive shaft disconected.......YOu will impress then with your long smoke burn out. Or if gears and tire are right, that neck snapping launch

If you have a D35, and bigger the stock tires, i wouldn't recommend removing the from drive shaft in low range:explosion


With 500 hp you would still make a quicker ET in 2WD.......With a roll cage and a properly set up 4 link!

The from tires wouldn't touch the ground, from launch, until at least, "60 feet", any ways,:shocked: :laugh:

O and that 500 hp would come with a new tranny and a D60 rear end now!

It can be done......there is just more feasible vehicles to do it to....as Dr Dyno has already said!

I'll see ya at the next stop light NOT!

Flash

Flash said:

don't ya know, thats the secret, for stop light to stop light racing!(Not that i have ever done this! )4lo and front drive shaft disconected.......YOu will impress then with your long smoke burn out. Or if gears and tire are right, that neck snapping launch

If you have a D35, and bigger the stock tires, i wouldn't recommend removing the from drive shaft in low range:explosion


With 500 hp you would still make a quicker ET in 2WD.......With a roll cage and a properly set up 4 link!

The from tires wouldn't touch the ground, from launch, until at least, "60 feet", any ways,:shocked: :laugh:

O and that 500 hp would come with a new tranny and a D60 rear end now!

It can be done......there is just more feasible vehicles to do it to....as Dr Dyno has already said!

I'll see ya at the next stop light NOT!

Flash

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The 500hp was just a random number. Have you ever brought your jeep to the track??? For the time you spend just sitting there spinning, or what I was doing was attempting to keep it at the brink of spinning, it still didnt seem to be much better than 4wd. Now trust me, with an open 500hp jeep you'll be much better off with 4wd. As far as a stocker AW4, 3.55 gears and 29" tall tires. In 4LO, you'll get slower average acceleration. Sure you'll move at a higher acceleration for maybe a second or whatver it takes to get through 1st gear, but'll it wont be that fast because you'l only make it to 20mph, and the torque converter slips too much, as well as the jeep basically "doesnt see it coming" and usually redlines and takes a bit to shift. However, if you go up a steep grade, you'll get better acceleration, trust me but i dont recall an drag strips like that...

Throw slicks and a locker in the back and you have a decent chance of beating a 4wd same power jeep. And dont start thinking im saying 4wd is better than 2wd, im just talking about open diff auto with stock sized tires. If you've got a 270hp stroker and an LSD, you'll deff beat a comparable 4wd launch (if used the whole way). One other possibilty for my poor launches would be that someone said the track had "the worst prep theyve seen there yet" so maybe on a good day i could grip and go in 2wd.