rxrom

iTrader: (2)

I have 2 convertible trans ams. One is totally stock. It drives like a regular car. Can't even hear it running. It idles at 500 rpm. Not a very fast car at all.

My question is about my other trans am. It has slp loudmouth and lid. That's all I know. It idles at 750 rpm. At 60mph the rpm is 1750. This car is night and day to the first. It is very fast compared to the stock car. I don't think exhaust and lid alone can make such a difference. How do I find out if it has other mods. It's a 98 auto.

Thanks

murphinator

iTrader: (2)

well before someone can post sarcastically I will say it straight up... its going to be hard for us to say what you have for mods over you when we dont have the car to investigate and you do.

Ok now that that is out of the way lets talk logical possibilities.

Intake,Exhaust ,Tune is pretty typical group of stuff to be done together especially on a convert car. I have a friend with a convert/SS pretty strong with just the intake/exhaust then I tuned it for him and it is definately a different car especially where yours is also auto between shortening shift times ,upping shift pressures and rpms a bit ,removing some torque management and getting fueling dialed into the hi 12's AFR it truely drives like a different car.

does the water pump look new ? because throwing a cam into the mix makes a lot of sense also allthough more intrusive and I would think you would be seeing headers on it if they had gone that route. if the water pump matches its surroundings then it hasnt recently had a cam slid in it unless they reused the water pump

zracer323

iTrader: (12)

If the idle rpm has been raised there is a good chance there is a bigger cam in it. Impossible to tell how big though. You could dunk it and find out where it makes peak power. That would let you know approx how big it is. Your rpm at 60 mph suggests you have stock 3.23 gears. Post up some pics and we may be able to spot more mods.

rxrom

iTrader: (2)

I'll try to figure out how to post picks. My main concern is future mods. I don't want to mod the car and make it slower.
How do I tell if a car has different stall.

murphinator

iTrader: (2)

you should see/feel the rpm's "flash" up much quicker than on your other car when you stomp on it and when your moving around slowly like around the driveway , in traffic , low speed driving it should feel like its slipping like its taking quite a bit more rpm's than your other car to get it moving.

if it doesnt havea stall theres your first mod to add - best bang for the buck on an auto car...

rxrom

iTrader: (2)

The car does feel like its slipping from stop. I thought the transmission was slipping maybe it's a stall. The stock gears should be 2.73. Hopefully the previous owner pun in different gears.

RPM WS6

iTrader: (3)

Don't put too much faith in the stock tach. My '98 shows an idle speed of about 700rpm in gear, but when hooked up to my scanner the actual idle speed is the correct 550rpm stock setting. You'll need to get access to a scanner if you want to know your true idle speed 100% for sure.

Did you verify the gear code to determine that it should be 2.73? It could have also been 3.23 stock, unless it's got the GU2 code for 2.73s. Either way, there isn't a night and day difference between these two ratios on a stock car (I've had both, the difference is pretty small IMO). If the performance is drastically different and behaves the way you described, it's more likely that the difference is stall speed.

Zlow28

iTrader: (11)

True, my car is actually at lower rpms than what the stock tach shows. OP, you should do a small video clip of the engine bay and under the car if possible. Maybe thatll help us out on bolt ons at least. Maybe we can hear a cam too.

rxrom

iTrader: (2)

I'll do a video clip maybe tomorow. Thanks every one

rxrom

iTrader: (2)

If you go to youtube and search rxroman1 you will see 2 vidios one of my red trans am and one of my black trans am. I can't figure out how to add the video. If someone can add it for me I ll apreciate it.

my bandit

iTrader: (10)

http://www.youtube.com/watch?v=_c4yZaKxkLw

http://www.youtube.com/watch?v=fWZK0...eature=related

there both practically stock to me. the red one doesnt have headers so i wouldnt think it would have a cam. it seems like an slp loudmouth (loudest thing next to straight pipes) and a lid.

rxrom

iTrader: (2)

Thank you for posting. The red car spins rear tires if I hit the gas. The black just chirps them. Maybe the slip lid and exhaust make the difference

my bandit

iTrader: (10)

no.. not really at all. how many miles are on the two? and other then what was stated before with the rear end gears, your pretty much unknown. they both have the stock ls1 intake (most ls6's have no egr) one just might be healthier then the other

91sonomast

What's the red bar behind the 98's rear-end? Is it just the body or something else? I thought I saw subframe braces but, I think it's just the body. The opened up exhaust will help free up some power so that could be the difference, or could be gears as stated by others, or even a tune. I'm betting that since it doesn't have many other mods it probably doesn't have a tune but, ya never know either.

rxrom

iTrader: (2)

The red car has 67k. When I bought it in 2004 it had 52k. I changed shocks to blistein, added subframe connectors, strano swaybars, panbar.

The black ta has 81k. I only bought it last fall just because it was cheap. Didn't do anything to it except change battery. It broke down and needed a fuel pump. I'm leaving it for my son (not sure yet).

RPM WS6

iTrader: (3)

Are these just regular Z-rated street tires? If so, even a 100% stock LS1 with the lowest performance gears (2.73) should be able to noticeably spin the tires from a stop. If not, and it's not on super sticky tires, then something isn't healthy.

PS. Air lid and loudmouth catback should be worth about 15-20rwhp combined, on average. So it's not a huge gain, but definitely worth something.

Sladester2

iTrader: (1)

You need to race them against each other.. There may not be as much difference as you are feeling.

rxrom

iTrader: (2)

The tire are summer z rated. Forgot which ones. Got them at tire rack. I'm going to put a lid and slp on black ta during spring. I'll see if that makes them same.

91sonomast

Exhaust can make it "feel" faster

rooster99ss

iTrader: (8)

One thing that I've noticed is that if you put 2 identical cars both stock from the factory right next to each other, one can be real slow and the other fast as hell. That's where the phrase "factory freak" comes from, and it's true