Why is my car slower than a Lumina?

[LeftVentricle]

1992 lumina 4 door 3.1L 3spd 17.02@79.87mph

My Celebrity weighs a couple hundred pounds less, has the same engine, and might have a more agressive final drive (assuming his 3sp has the economy 2.84, I have 3.33). Why am I running a mid-18, and even a nineteen?!

I've been thinking that it's the transmission. I have tentative plans to rebuild it in February, but I'd like to hear what you guys think. I've put 26k on the engine since it was rebuilt, it runs awesome and gets 27-29 mpg highway, and basically everything but the tranny is new or refreshed. I even carried less fuel (and less wife ) and had better, wider tires for a later run this past April and the best I could do is a 19.3. I don't have the slips anymore, but it only went downhill from there. Hell, my '86 Suburban (350, 700R4, 3.73) ran a 19.2, this much lighter car should be able to do way better.

[SappySE107]

I got 40 mpg all highway with my 3.1/4T60 (3.33 FDR) grand prix. How much does a celebrity wagon weigh?

[LeftVentricle]

According to the title I got from the PO, 2900# empty.

[1988GTU]

Are you spinning at all? Looks (from your sig) like it's low in the back.

[LeftVentricle]

It will spin if I floor it. I don't think it's low in the back... Here's a larger picture, with bonus daughers.

[SappySE107]

And you are sure you have 3.33 FDR like the W bodies?

[LeftVentricle]

My SPID lists GX3 as one of the options, which is the 3.33 FDR.

[SappySE107]

Hmm, are you running the stock 89 computer/chip? Do you have any way to scan?

[LeftVentricle]

I don't know for sure. The PO said he hooked up the Celebrity computer and chip. I have no scanning tools. To be honest, I don't even know if this engine actually displaces 3.1 liters.

The PO said the stock 2.8 cracked the block, so he swapped heads with a Cavalier 3.1 which had a bad head and dropped that in after doing a dingleberry hone of the bores (and little else; I've had to replace fuel injectors, alternator, radiator, axles, brakes and shocks/struts all around). I know 2.8 and 3.1 are mechanically identical aside from the crank and pistons (so I have no ready way of telling), but unless the transmission is being a ridiculous drain, this car should be faster.

[Superdave]

It's a wagon with around 100 WHP, it's not going to go fast.. unless you make it go fast with an engine swap or a turbo. 18's and 19's in the 1/4 is about right. A stock 3.1 automatic cavalier runs mid to high 16's weighing in at around 2700 lbs.

Honestly, with that setup i'd just be happy with it running and getting around town. Don't abuse it if you want it to last.

[LeftVentricle]

It's a wagon with around 100 WHP, it's not going to go fast.. unless you make it go fast with an engine swap or a turbo. 18's and 19's in the 1/4 is about right. A stock 3.1 automatic cavalier runs mid to high 16's weighing in at around 2700 lbs.

Assuming a ludicrous 25% drivetrain loss, yes, this 3.1 is only getting 105 hp to the ground. How does +200 lbs equal a loss of two seconds? And then, in the case of the W-body, how does another +200 on top of that equal a gain of more than a second? Isn't the rule of thumb a tenth for every hundred pounds, either direction? Not attacking you personally, it's just a little frustrating that my car theoretically has the same power as, but is slower than, a heavier car. And honestly...

It's a wagon

I don't think it being a wagon has much to do with it. It's got very similar aero and nearly identical weight as non-wagons. I'm sure if this were a sedan or coupe and everything else were the same I'd still have posted this thread, but probably would have been more upset.

Honestly, with that setup i'd just be happy with it running and getting around town. Don't abuse it if you want it to last.

I don't see it as abuse when I've only tracked it twice and don't engage in stoplight wars. Besides, a GM car will run poorly for longer than most other cars will run at all. However, I intend to fix everything else wrong with this car once I get my tax return in February.

...Again.