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2500 Acceleration

M

mtnbkr

GUEST
Last night, I took a 2500 with a 3:73 rear end for a test drive. ?Although I was highly impressed with almost everything, I was a little disappointed with the power. ?I must say that my 2000 Jeep GC is in a whole different league when it comes to acceleration (I know, it's in a different league when it comes to breakdowns and other things as well). ?Dealing strictly with acceleration, however, my point is that the 2500 was nowhere close (and I mean nowhere close) in this regard.

I don't mean to offend anyone with this comment. ?In fact, I'm still going to get the 2500 (but with a 4:10 rear end). ?Presumably, once I experience the massive torque from the 8100 pulling my travel trailer through the Rockies, I will forget about the acceleration issue.

Did anyone else feel the same way (with either the 1500 or 2500) after the first drive?
 
It's all about the power to weight ratio. The BB Av is a pretty heavy beast, approaching 7000lbs.
 
Steelheadchaser,

I hear what your saying, but doesn't the 8.1L at 340 hp and 6800 lbs. have more or less the same power to weight ratio as the 4.7L at 240 hp and about 4,000 lbs.? Litres to weight favours the 8.1, while hp to weight very slightly favours the 4.7, as does torque to weight. There doesn't seem to be much difference between them on my calculations. Am I doing them wrong?
 
I actually was very surprised when I test drove the Av initially.....it was a 1500 with the 3.73's and felt for the weight this thing moved pretty nicely....I haven't had the opportunity to ever drive the 2500 but I can only imagine that the torque down low must be pleasing...... :B:
 
At 20 lbs/hp, the 8.1 L Av has about 20% more weight per pony than the GC (16.6/hp) you cited. Pretty significant difference.
 
Put a loaded trailer behind the jeep and the same behind the 2500 Av and you will see who is faster :B: The 2500 Av is meant for towing and not for racing. If you want to go fast from street light to street light get a sports car and not a Av. Or get one of each and when you feel the need for speed get in the sports car. At least that is what I try to do :B: It is hard to have both in one vehicle.
 
WS6Y2K,

Believe it or not, on even odds I'd put my money on my Jeep over the Av with my fully loaded 5,500 lb TT. I've pulled it through the Rockies through high elevation mountain passes countless times, consistently passing turbo diesels which couldn't go more than 45 mph on the hills (granted with larger TT's possibly). The TT dealer who drove my JGC towing the TT was amazed. I'd obviously take the Av pulling anything heavier, however.

Again, don't get me wrong. I love the Av. I ordered one yesterday. However, putting aside Steelheadchaser's valid comments regarding power to weight ratios, I would have thought that an 8.1 L engine generating 340 HP and 455 lb ft of torque would be capable of moving the 2500 much more quickly than it did. Maybe the 4:10 rear end will make a difference (although I can't imagine it will be that much).

Are acceleration and towing ability really mutually exclusive? Why can't you have both with the same engine? Before I blew my engine, I thought that the Jeep hit both marks quite well. I had never had any problems pulling my TT (friends with a Tahoe could not maintain my pace) and it did in fact smoke from street light to street light. Everyone who rode in that vehicle commented how quick it was. If you have driven a JGC with the 4.7, I'm confident you would agree with me.

So...my question is - are acceleration and towing ability mutually exclusive? Can you not have both with the same engine? Why not? If you have both, is the life of the engine jeopardized (as in my case)?

 
I think it can but it is going to cost you some money. Ask Gandolphxx. I hear you can now order the Av with a wipple S/C from the factory at least for the 5.3 not sure about the 8.1.
 
Is this factory whipple a GM wide option for the 5.3L Av or is this just a dealer installed item....reason why I'm asking is because I've been trying to keep my eye on this for awhile now and I haven't seen anything yet confirming this......would be nice to put the blower on and retain your factory warranty...I can imagine this is what holds folks back from doing so....that and the $3000+ price tag on the supercharger... :B:
 
Mntbrk,

Welcome to the club.

SHC is right about the power to weight ratio hurting the AV. But I think you?ll find that the 5.3 and 8.1 have a better power in the mid and upper range than your Chrysler engine. The AV with either engine power train is not designed for drag racing as the power builds up as it goes.

I had a 98 Durango with the 5.2 and 3:98 rear end. It was faster out of the hole than my AV and would smoke its 31 inch tires but the power went flat after that even with the 3:98. My AV has more power and if you check around this site you?ll see that many of us are always trying to add more of it to our AVs. I have no regrets on getting rid of the Dodge (it's just not the same company any more after the buy out).

Pick what works for you.
 
Don't forget that nasty computer in our AV's. The throttle via computer and torque management system kill the acceleration from a stop. Better bet is a 10 mile per hour rolling take off. The TMS will pretty much leave you alone above 10 miles per hour. Someone on the site just took their 2500 across a set of scales and it weighed 7032 pounds. Thats a lot of weight for 340 (at the fly wheel) hp to move from a dead stop, even if the computer didn't get in the way. With about a 28% drop in hp to the wheels on a 4x4, you're only getting about 245 hp to the ground.
 
Some folks fail to realize that the hp figure is at the flywheel not at the wheels...I know before I started getting into car's etc...I used to always look at that figure and say wow...that's a lot of ponies....it's a different story when you really think about what % of that is at the rear wheels.... :B:
 
How many miles did the test vehicle have on it? My 2500 (4.10s) was really tight for about 3,000 miles. In fact it kept improving until it reached about 7,500 miles. One of my buddies that drove it when I first got it and just drove it last week (30,000+ miles) could't believe I hadn't modded the engine.

I've pulled a 7,000lb trailer up the mountains and never slowed down. I have pulled 13,500lbs (oops) up some big hills and she does a very good job. A Whipple SC would come in nice when I'm trying to pass someone pulling my 24ft car hauler loaded to 10-12,000lbs >:D
 
Zimms...I think if that twin-turbo Trailblazer ever makes it to production...we might be in some trouble... :cautious: :B:
 
Zimms...I think if that twin-turbo Trailblazer ever makes it to production...we might be in some trouble...
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They would need to change up the looks of it for me to consider it against another Av when the time comes.

I really liked the looks at first, but now they're too common and plain IMO.
 
More of an aggresive look and definitely if your going to twin-turbocharge that thing.....a more appealing appearance package....ground effects etc... :B:
 
I have a 2500 with the 4:10.

It was reasonably quick for a 7300 lb vehicle (with me and 37 gals of gas.)

I spent just a little over $1000.,
(Volant Intake; Flowmaster 50 Big Block with dual 3" in / dual 2.5 out, and 2 pipes straight out the back;
Direct Hits Ignition, and HPP3) and I don't need it to be any faster than it is now!

I haven't timed it yet, but it feels about the same as my stock Maxima (0 to 60 in 6.7 sec.) It might not actually be "that" fast, but I have absolutely no trouble merging onto the busiest freeways at 80 mph by the time I get to the top of the ramp!

The 4:10 WILL make a huge difference,
and you will LOVE your AV. ;)

Oh, by the way, BEFORE the mods, I took a trip through the mountains of WV, VA and NC... pulling a 4500 lb trailer. I could go as fast as I wanted at any time, and it only downshifted on its own two times on each 500 mile stretch (with the cruise set at about 75). I won't complain about that! (y)






 
Seven,

That is excellent to hear. I'll check into the mods as well (being careful since I'm leasing). Thanks a lot for the response.
 
mtnbkr said:
Seven,

That is excellent to hear. ?I'll check into the mods as well (being careful since I'm leasing). ?Thanks a lot for the response.
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mtnbkr:

No problem - happy to help! ? :cool:

If you have any questions about any of the mods or anything, feel free to send me a message!

In general, at lease turn-in time...

HPP3 - takes just a few minutes to reinstall the factory programming - they would never know you had modified it! Then, you sell the HPP3 on eBay for 50 to 70% of the original purchase price!

Direct Hits - if you wanted, you could unscrew the capacitors from the tops of the spark plugs - the plugs and wires will work just fine... ya "might" have to pull the plugs to widen the gap back to factory specs. Total time, one hour max. ?If you were to pull the capacitors, and switch back to the original wires too, you could probably buy a new set of plugs to go with it, and sell the Direct Hits on eBay!

Volant intake: You do not "ruin" any of the factory components... keep them in a box then switch back before turn-in, and sell the Volant on eBay!

Flowmaster: Great bang for the buck.
Muffler: about $119., installation, you can expect to pay about $100. ?I had the guy at Monro cut the muffler and factory tailpipe off with just 2 cuts - they can easily be put back on! (Might cost another $60. or so) For that matter... the factory 2500 muffler has 2 outlets anyway - you could just leave the dual tailpipes in place, and just have them put the OEM muffler back on - that would be even cheaper!

So, if you want to improve performance and gas mileage while it is "yours" you can do so, and reverse everything before turn in, and get about half of your money back! ?(y) ? ;) ? :D


And, while I am not a GMAC warranty rep, I do have about 10 years in the car business... I cannot imagine any warranty item that would not be covered due to the muffler or ?Volant. ?Direct Hits claims "no problem" as far as warranty is concerned, and Hypertech recommends reversing the programming before you take it to the dealer for service. But, many members here have taken theirs in for service with the enhanced programming without any problem! Depends why you are taking it in... if it is computer or performance related, I would reverse the programming first. ? ;)

Have fun!

Dave (Seven)




 
Dave,

Thanks so much for a ton of useful info. If I really like the Av (and what's not to like), I'll buy it at lease end.

In the meantime, I'm going to check out your suggested mods. I can hardly wait for its arrival in December.
 
MTnbkr...did you calculate how much more you will pay buying it off lease as opposed to buying it in general?.... :B:
 
NJAV said:
MTnbkr...did you calculate how much more you will pay buying it off lease as opposed to buying it in general?.... :B:
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Good point, but frequently, lease payments are much less than purchase, which is one big reason leases are so popular. The MOST important consideration is being able to stay within the allowed miles if dropping it off at the end is a possibility... the fees can be unreal... I have seen folks have to pay several grand in fees to drop it off at the end. And do not even consider trading it in before the lease is up... you will be sore for months.

THE GOOD NEWS: :D
Often, lease companies will flex on the buyout price! They would MUCH rather sell it to you than take it to an auction, and therefore are often willing to drop the price if the customer wants to buy it at the end of the lease. The key is do not let them think you "definitely" want to buy it. Just tell them that you would "consider" it if it were less! (I'd offer $1000 or $2000 less than the stated buyout price, and see what they say.) Chances are good that the rep you talk with will have no control over the price - you will need to talk with someone with some authority!

BTW: you MUST talk to the LEASE CO. directly - not the dealer - if you buy it from the lease co, the dealer gets nothing (unless they run the paperwork.) They would much rather sell you something else, so they will not sincerely try to negotiate with the lease co on your behalf... they will say "Sorry, they won't come down on the price, and here's (about 10 reasons) why you should forget that and buy a _____ from us!"





 
mtnbkr said:
Dave,

Thanks so much for a ton of useful info. ?If I really like the Av (and what's not to like), I'll buy it at lease end.

In the meantime, I'm going to check out your suggested mods. ?I can hardly wait for its arrival in December.
Click to expand...

No problem! Happy to help! :cool:

I can hardly wait for you to get it too...
always nice to add another happy owner to the club! (y)

However, before you sign the papers when it comes in, you should take NJAV's advice and consider a purchase... by December, they just MIGHT have a 60 month 0% rate again, which can save you HUGE bux!!! (On a $36k loan at 9% the total interest is almost $9,000! :eek: Pmt is about $747. per month, compared to $600. per month at 0%!)


 
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