I have heard that the trans am lt and ls1 are under rated to match the numbers of the z28. I realize this is a z28 board Just curious as to if there's any truth to this. Thanks

 

ummm, being that they are rated the same because the motor that they have are EXACTLY the same, i would think that they are rated right.

now, if the question was, "are lt1 and ls1 camaro's/firebirds (aka F-Bodys) under rated?", then that might be worth investigating.

but i figure the lt1's are probably right on with their production output figures, and there is no difference between the camaro's/trans am's for sure.

lt1 in a f-body is an lt1, and ls1 in an fbody is an ls1.

only differences are the vettes, which are rated a bit higher.

 

I haven't heard that, but I've seen some dang impressive dyno numbers from TA's, the ones I've seen they tend to dyno about 5 to 10 hp more, could be coincidence on the cars I've seen though...I'd kinda like to know what everyone else has heard on this...

 

I've heard that it is about 10-15 hp that the t/a's are under rated. Ofcourse they have the same engine, but don't they have slightly different components or are they EXACTLY the same?

 

I have read in mag's that f body LT1's were suspected to be underrated to the tune of 5-10 hp whereas the f body LS1's were underrated 30-40 hp. Both were dyno'd and when calculations were performed to get the flywheel hp rating's, it showed more hp than the factory advertised. Actual numbers I believe was around 285-290 fwhp for the LT1 and 335-340 fwhp for the LS1. Its been awhile since I read the articles so the numbers may not be exact but suffice to say, both were underrated with the LS1's being more so of the two.

 

Seems like most LT1s dyno close to or slightly under the "275 horsepower" figure...i'm not gonna even go into the 96-97 dual cat stuff. But most LS1's seem to be dynoing higer than they're stated figures. When the LS1s were still fresh, I remember many magazines doing multiple dyno tests and there was one Trans Am convertible that actually dynoed higher than a same year vette. I think the 2001-2 T/As and Z's with the ZO6 intake dyno at like 320 at the rear wheels, which is quite awesome.
I remember pulling away from 2 LS1 vettes with my 99 Formula with only 20TL exhaust and 4.10 gears, one was a convertible though.

 

The drivetrains of any given year are identical. Granted, there were some ram air Pontiacs that had a higher horsepower rating that the Chevys did not have. Engine internals were not different, though. The only other differences would be weight, with the T/A being considered the heaviest of them all, due to luxury options and large rear spoiler.

 

Shoebox you're one of the most knowledgeable guys here, the TA's supposedly weigh the most but from what I've seen/read they perform as good and in many cases better then the Z28 counterparts coincidence? I haven't had mine to the track so I don't know how it performs but it definately is no slouch.

 

The thing is, there are no facts to support that one model should be faster than another, except maybe by weight difference. We all know they were all assembled on the same line at the St. Therese plant. Under the skin, they are the same cars.

 

its possible that the T/As more streamline appearance can have less wind resistance than a Z28 but taht would be the only difference and it cant be THAT much of a difference. i will say however that the ram air setup on a WS6 T/A is far superior to taht of an SS or regular factory air box of a Z28. that difference you can see on the dyno and at the track.

 

no

LT1's are not under rated. yo just have the 1 in blue moon freak. no under rating.
+ or - 5 hp doesn't make for under/over rating.
its jst tolerances and inaccuaracies on dynos and powertrain loss ect...

 

I think the numbers for the LT1 are pretty accurate, the LS1's on the other hand are DEFINITELY not.

My friend Dyoed 325 RWHP on his 2000 Z28 A4 with K&N/lid/Flowmaster, and intake free mods. He also pulled 107mph at the track. I pulled 104mph my first time at the track with the mods listed below. I would say mine is very healthy compared to other LT1's I've ridden in.

 

Are the mufflers the same on the TA's? I know the exhaust tips are all different, but are the mufflers the same on the TA's and Z28's?

 

what about the ultra-z hood and intake from slp for comparison to the ram air WS6

 

Seems like it's a pretty interesting question. I first heard it from a z28 guy. He simply said ..."the t/a's have a little bit more power" who knows