LT1 years???
 

are there years of LT1 engines that are better than others in the f-body?
i know they revised the exhaust lobe cam late in the 1995 model year to gain 10hp and a few ft/lbs, but are there any other significant improvements/updates between 93 and 97?

I know 93 was speed density and its a b*tch to find tuning stuff for it.

1995-97 are thought to be 'better' in general. I say this because they had vented opti, larger internal fuel rails and crank position sensor. So for modding they have things you can use. 93+94 are each a bit different in their own ways, but the 94s have more in common with the 95s then the 93s.

Internally not much different in the short block. Actually the 93s had higher lift cams. 93 = 460 lift. 94+ 449 lift. The dual cats and revised exhaust manifolds contributed to the HP and torque gains. The 92-94 heads are suppose to have smaller water jackets so they can be ported a bit more, but still not enough to equal aftermarket.

1992 (vettes=LT1) - 93 had hardened pushrods, different fuel system, intake is very different then later years, injectors, fuel rails, FP regulator, oil filler tube, cam ( 93 cams have a smaller hole in the fron and a factor 93 can will not work on a vented opti car). Shorter opti drive pin.timing cover/timing chain/opti, and the alternator and TBs are specific to 92-93 engines.

There allot of other differents such as cooling system and electrical as well if you need that kind of info?

JB

I put a MSD vented opti on my 93 and its amazingly better.

Also I'm gunna agg to Tims question. Did all the LT1 cars have differant gr ratios in the t56s depending on the rearend ratio? Cuz I wanna look up the mph differance with the 3.73s but IDK wat grs were in my car factory. I look it up and The trans ratios are differant for cars with differant rear ratios.


Axle Ratio 2.73
First Gear 3.36
Second Gear 2.07
Third Gear 1.35
Fourth Gear 1.00
Fifth Gear 0.80
Sixth Gear 0.62

Axle Ratio 3.23
First Gear 2.97
Second Gear 2.07
Third Gear 1.43
Fourth Gear 1.00
Fifth Gear 0.80
Sixth Gear 0.62

Any way for me to look anywhere on the car to find out whats in the trans?

For the 93 t-56 if the car had 2.73 gears it had the M28 trans which had the 3.36 first gear. If it had 3.23 gears it had the M29 trans. which had 2.97 first gear. 94 and up had 3.42 gears which had 2.66 first gear.

OK, SOOO how do I tell which one is in my car considering when I put the 3.73s in the grs that where blown up where Richmond 3.42s? Can I look on the trans anywhere?

It says on the RPO sheet in the console M28 or M29. Also you could go by the RPO GU2 for 2.73 and M28 car or, GU5 for a 3.23 and M29 car.

Easiest way to tell on a 93 is to just look at your Speedo, if it goes to 150MPH you have the PEGII package with is the M29 trans and 3:23 gears

Just as an FYI:

On 93s there were two options for the Z28, PEG1 and PEGII.

PEG1 was 125MPH Speedo, 235 ( None Z rated tires ) tires and 2:73 gears and M28 trans. computer will cut fuekl at 117MPH.

PEGII has 150 speedo, 245 Z rated tires, 3:23 and no speed limiter.

Intake manifold and fuel rails were different in 93-94. Vented opti starting in 95, cooling system was a little different starting in 95. I've heard from a lot of people that the heads from 93 were a little better than the rest of them flow wise. Oh yea, the three versions were 93-94, 95, and 96-97. Timing cover was different on all three versions. If you start to build one from the ground up, just make sure the short block stays consistant year wise.

the maf in the 93 was different from all other years or something like that

Umm... yeah, something like that or, not.

There was no MAF on the 93's - they were speed density.

- Justin

Wasnt aware of the cam change...Except for the change from speed density and gear synchros in 93 it wasnt much. I thought the 10 hp was attributed to the change from single to dual cats in 96 and 95 in cali cars. I never seen any evidence that the dual cat cars ran or dyno'd any better.

Me either, you have to guess marketing, a 10HP gain is nothing and every car is different, Gm couldn't say they made a change and lost HP!

We dyno'd a bunch back in 96 and saw numbers on stockers range all over the place, some real low, some near 290 at the wheels. We dyno'd a few band new SS's that put down no more then a plain Z and yet another new 96 SS dyno just over 300 at the wheels?

In Z28s and T/A The 93's are "claimed' to be faster, some say because of the Speed Density, other say weight, other say different gearing in the manual trans. But I don't know that's ever been proven, But an SS will cover them all, better posi and wider tires allow them to get more power to the ground off the line regardless if the ram air helps?

I heard the same about the speed density cars being faster because of the differance in gearing...but im not sure what your talking about w/ the 96 Lt1's putting 290 to the wheels and the ss's over a 300..thats insane. The LT1 6spd ss's did seem to put out a little more (unlike the LS1 SS's) but the highest ones generally pulled 270's (on a very rare occasion maybe high 270's)...I owned 2 LT1's (when it was still the car to beat) and spent alot of time at the track and different boards and thats the highest I ever heard outta them. As far as the best time we all know about the firechicken GMHTP car that ran 13.5's. Im skeptical about that mags times, best I ever seen was a 13.6 Out of a 96 SS 6spd which cut a 13.6@101. From my experience the formy's were always the fastest. Low optioned and the lightest.

i have a cold air and the best i ran was 13.553

Trap speed, slip, anything?...curious...Its very possibly.

He's also got 3.73s....full slips are posted in the Drag Race forum....

- Justin

j0n's LT1 was a hell of a runner. 96 TA vert 6 speed. stock motor, full exhaust, cai, a mail order tune, 4:10's and drag radials. at 3600 lbs he ran 12.7 :shock:

Well that explains that, thats what a LT1 should run w/ gears and cai.

That's Jon though...definitely not your average driver :nod:

i wouldn't buy anything for the first couple years it's out. theres almost always problems and recalls and crap. i work at a ford dealership and i don't know if anyone knows about diesel trucks but the newish 6.0 took a nose dive. it's the most popular diesel we work on. people saw the previous 7.3 as a great motor (which it is) and though the new 6.0 would be better. not always the case. the point is wait till things become developed. Bottom line 95-97 lt1s are better then 93-94.

Funny you should say that, most Lt1 owners including i would disagree. Most prefered the OBD1 cars .Newer doesnt always mean better.

The real LT1 was only produced in 1970-1972.

Then whats 92-97 the fake LT1