Jancorvette

First trip to the strip on my 97 LT1 Trans Am. My mods are long tube pacesetters, off road Y pipe, hooker catback and 4.10s. Went to the track and the car only trap 99.5MPH. With my mods i was hoping for at least 102-103MPH. Is this normal? I have 19 inch corvette c6 wheels, could these wheels be bringing me down? Something i should check. I am a MN6

pillarpod

I'd say thats normal

Jancorvette

Really? This was my analysis

Stock= 96 MPH
4.10=3mph+
Headers and exhaust = 3mph+

At the end, at least 102MPH. This were approximadetly the same gains i got with the same mods on my LS1 corvette. My Corvette was trapping 108-109MPH with the same mods. taking away the 50whp advantage of the LS1 vs LT1 and we arrive again at the 102MPH. But Drag racing isn't always math

LT11996

Are you spinning a lot when you take off? I would think with 4.10s, it comes down to what tires you have and how good you launch it.

sweet-94z28

iTrader: (30)

How good was your traction on both runs? Honestly, I have found with my Trans Am that traction plays a part in trap speed. For some reason, if I spin a lot, I will trap a faster MPH but a lower trap time than I did when I got decent traction. I have a slip from both street tires and drag radials, and I dropped from 119 MPH to 117 MPH but went from a 12.49to a 12.38 on the same day, same weather. My 60' times were very different at 2.01 to a 1.82 (3.42 gears ).

If your C6 wheels are aftermarket chrome, they may be a little heavier than the stock wheels (a lot of aftermarket chrome wheels are steel). More unsprung mass to move and more mass to rotate will definitely take away from the cars ability to accelerate.

Jancorvette

my best run was 14.5@99.5MPH with a horrible 2.5 60 ft. But regardless of the horrible 60ft, the MPH is the true indicator of whp and weight. Thats whats got me worried. I know, with a good set of tires , i cut my 60ft to 1.9 at least and i will be at 13.2@100mph. But the low trap speed is my worried.

Jancorvette

they are chrome. I believe that these huge 19 inch wheels are killing my trap speed. Stock the car comes with 16 inch, so i think you be right with the wheel size, mass

guppymech

iTrader: (7)

I'd say you're in the ballpark. I went from 97mph to 101 with gears, headers/cutout and new valve springs. Little things that pick up a mph here and there add up. How many miles on the engine? Done a tune up lately?

Jancorvette

My engine has 30K miles original. I know that I am in the ball park. Going tried to get some 16 or 17 inch rims and see if I pick some 1 or 2 mph. I changed the oil recently but no plugs. I have no cats, and have not tuned the ECM. Don't know if this also can be affecting

TravisMcGill2000

iTrader: (2)

The 2.5 60ft got alot to due with trap speed. You probly also spinning when u hit 2nd. This causing you to loose mph. I bet with sticky tires you will trap 102 with ease. I was trappin 108 when my car was bolton only.

IDriveChevy

iTrader: (5)

I trapped 13.99 @101 with 18" wheels. What kind of trans do you have? You could be spinning given the bad 60' times.

marc97taws6

iTrader: (6)

My full exhaust, stalled, 3.73 auto Ws6 trapped 103.33 in 2700DA with a 1.74 60ft on a 275/40/17 DR with stock 17x9" ws6 wheels up front.

You should be able to get right around there or even exceed that if conditions are right!

F0x Slaughter

I trapped 103 pulling 2.4 60'

Ed Wright

iTrader: (1)

Big heavy wheels will effect both your ET & MPH. Mass is a bitch.
I have not seen poor 60's effecting my MPH a lot.

trilkb

iTrader: (4)

Its basic drag strip knowledge...

the quicker you get down the track....the quicker you get down the track.

60fts can be weird when they influence trap speed. A 2.5+ 60 is BAD. A 2.0-2.2 60ft isnt great, but they tend to trap higher. 1.7-1.9 will trap lower. Its like...there is a cutoff to the rule, just because you do a 3.0 60ft doesnt mean youll trap 105.

But in the end the quicker you get down the track, the less time you have to speed up...make sense?

Did you make any runs with around a 2.0 60ft?

14.5@ 99 says something by itself though. Most 14.5 runs in these cars stock get you around a 95-96 sometimes even 94mph, atleast from my experience. I think one of my few 99mph runs with a 1.9 60 I ran a 13.6. Car had a ls1 lid, cutout, stall, 3.23 rear, nitto Nt555r.

Some people get lucky, Ive personally NEVER seen a lt1 or ls1 car run "magazine" or "forum" times at my local track. A joke my buddy and I have is if you say your car should run low 12's next time out from whatever mod you just did, in reality it will be a high 12 low 13 lol.

How are the plugs and wires? what O2 sensors are you running?

Jancorvette

I know that the lower the 60ft, the lower the trap speed, but as you stated it does not mean a 3.0 60ft will make trap 110. I have not changed my plugs. I just bought the car a few months ago. Been puttin in headers and diff. I have the factory 02 sensors up front and a ory pipe in the rear. As you know the check engine light is on. But i believe that rear 02 sensors dont affect performance. I believe the issue is mainly due to the heavy 19 inch chrome wheels, but will also check plugs and wires

F0x Slaughter

What was the ET?

Also why would you want to run a rim that big anyways?

Are you a gangsta?

Ed Wright

iTrader: (1)

If a stick car spins a little they often pick up a MPH or so. None of my automatic cars have done that. Just about no change to MPH at all. My normal 60's are 1.26 to 1.30, depending how high it is at 60'. If it just flat blows the tires off it might go 1.45, front end not up at all. MPH will not change from a good pass. Only time it ever does that is on a bald starting line. I used to have a stick shift 265" 1956 Chevy Stocker. (Late 1960s) that ran right at 13 flat. It would pick up MPH if it spun. It appears to effect lower hp cars more.

Ed Wright

iTrader: (1)

Ha! I call those Pimp Wheels. LOL!

F0x Slaughter

Found his car =)