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Lt-1 & Auto/manual

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FordNoMore!

Guest
Hello fellow Vetters,I am the newby on the block, I have been reading this forum for couple weeks now and is seems to be full of great helpful technical support towards the vette owner/owner to be!, which brings that to me, I am in the process of finding a Vette, my abject is to find a 93-96 low milage vette,preferable a 96 LT-4, but like other things $$$$ dictates my search,my question to all of U out there in techno landis, I have read post comparing the l-98/LT-1 motor/tranny combonations, I do believe that a post was posted that if U go with L-98 a automatic was prefered, and if U go with LT-1 get the manual tranny for launching purposes, my question is if I go with a LT-1 and automatic, what am i losing as far as performance wise, and if so what mods can be made to the stock auto tranny,(torquconverter,reprogramming,tranny kits etc,)I allready know about the opticrap, and other little chevy quirks, My friend is a late model Impala Freak, and has every part in the world,lol. So let me know what U all think, and any help would be appreciated. Lets make my change from the Mustang world to the corvette world a great experience. Thanx and peace
 
C

Chris N

Guest
LT1 and auto

I have a '96 LT1 with auto and am pretty happy with the performance. I was looking for an auto though, for ease of daily driving.
The LT1 is lower on torque than the L98 and the auto might have a very slight lag when compared to a manual, off the line.
I've been happy though, as drag starts aren't inportant to me.
What I would like to do though is lower the gear ratio, that would help with the off the line stuff / "torque", I thing.
Chris
 
R

ron

Guest
LT 1 - auto/manual

I think that the debate surrounding the choice of transmission for the LT 1 Vette should be partially based on what one plans to do with the car, and whether or not either transmission type is suitable as a matter of choice. If off-the-line performance is what you are looking for, then you may prefer the manual; however, for reliability and ease of city driving, the auto does exceptionally well. For what it is worth, I drive a 93' convertible with almost 100,00 miles and have not experienced a major problem with the engine or transmission. Granted I don't race the car (in a formal sense), but do use it as a daily driver and keep all scheduled maintenance up to par. These cars are very well engineered ,as most on this site will attest, and they will give great performance over a long period of time if taken care of. I guess, ulltimately, the choice of transmission and engine is really a personal call. I would suggest driving each and then make the judgement based on results. Good Luck!

Ron
 
F

FordNoMore!

Guest
LT-1/AUTO/MANUAL

i guess my next question would be, what mods can be made to the auto tranny,that will upgrade its performance, for better off the line performance and overall drivability,(computer shift change, torque converter)etc. thanx
 
L

LT1Vettepilot

Guest
I've got a '96 with the automatic. If you are looking to do much spirited driving, I highly recommend the LT4/manual or a 93-95 LT1/manual. From what I've found in the short time I've owned the car, the transmission doesn't shift anywhere near when I want it to. Coming from driving a sports car with a manual in it for the last 8 years, I find myself manually shifting the auto because its faster for me to do it than to wait for the transmission to decide to do it. I've also driven a '93 LT1 with the 6 speed and the response is much better than that of the auto, as is to be expected of course. The only thing I can think of as far as after market goodies goes for the transmission is a high performance torque converter. I don't know what it would do for you though. Engine wise, if you get the LT1, throw in a set of roller rockers, and a 52mm throttle body, and a reprogram (pre-OBDII cars-i.e. prior to '96 I belive) you would be sitting about at LT4 power. Maybe a little more.
Something else to consider is your mileage. The manual gets much better mileage, especially on the highway, when you are just out cruising around. I've been getting right around 20-22 MPG with a combination of highway and city driving around here, and about 18-19 MPG when I've been playing with the car. Thats not a bad average MPG when you figure in the heavy foot. On the open highway, I averaged 26 MPG over a 12 hour drive. The manual on the other hand, gets much better mileage. See Vettepilot's post under LT1 top speed for the story...but his '93 manual was getting over 30 MPG on the highway (35mpg I belive)and an around town average in the mid-20's. He even got 21MPG at 140MPH. I don't believe the auto will touch that. Anyone get an automatic up to 140 to check the mileage???
I hope all this helps you, and welcome to the CAC:cool

And don't forget to wave :w
 
D

Don Martin

Guest
I owned an 85 4+3 (stick) that that had a rebuilt engine that ran 100%. My 92 LT-1 with the A-4 is much, much faster and gets a little better mileage too!

I think that in the real world drag racing that the auto will take the sticks almost all the time. It's because of driver error.

But like others have said or infered. Get the tranny you want.

I feel that the C-4 Corvettes while well "engineered" are not made well. They go fast but break down a lot and when they do it's big, big bucks to fix them. But this is a racing car and speed costs money.

My 92 coupe has the performance axle (3.07) and the A.-4. The engine runs very well and is 100% stock. On a clear day with high barometric pressure it does 0-60 in 5.1 sec and 13.7 to 13.6 in the 1/4 mile. The tires are stock GSC's.

My old tranny was "beefed up" according to the previous owner to shift all gears at the red line. This "beefed up" <-----sellers words tranny died on me and it cost $2,000 for a new one. The new tranny upshifts 1-2 at 4,800 rpm so I have given up on this car. With all the other breakdowns and the codes it's showing I am sick of fixing it. But it's still fast and a blast to drive.

If you do get one. Be careful with the driving.

I get 25 mpg on the interstate driving it like a Corvette. If I drove it like a old lady it will get up to 27 mpg.

There is a thread here on C-4, A-4 mileage on the Autobahn at very high speed. It's not good. But I don't think thats a issue in the USA for street driving.
 
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wulf

Guest
Hi Don,

you state that your acceleration is 5.1 to 60 mph with the 3.07 performance rear axle ratio. What is the top speed you achieve with that ratio or - you might not have had the chance to test it - what is the rpm/mph retaion in the OD lets say e.g. what rpm are necessary for 100 mph?

Would be great to hear from you!

wulf
 
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Don Martin

Guest
Hi Wulf,

Sorry for the late reply. That time of 5.1 sec is in clear weather with high barometric pressure and cool temperatures. In hot humid weather and low pressure I have seen times of 5.6 sec.

With the old tranny that just bumped the rev. limiter it did a best 0-60 of 4.85 sec and about 5.0 average. Now the new (CRTA factory rebuild) shifts 1-2 at 4,800 rpm so I shift manually 1-2 when making these tests. They are all measured with a GTech Pro performance meter. All testing is done on the level and I go the other way too. I leave the ASR traction control on as with these old GSC tires and axle ratio I have there is too much tire spin.

I don't know what the speed is at the 1-2 shift at the red line but the 2-3 shift at about 5,500 rpm is about 80 mph.

I do know that the tranny will shift 3-4 when in OD at about 115 mph and I keep it in D to the red line at 135 mph. This is very important to get the most out of it.

The car will do the 1/4 mile at 13.7 and 108 mph any time and in the best weather 13.6 sec. Note that the mph is from a GTech and it gives the true speed and drag strips give a average speed which is about 2 mph slower.

The engine is stock and has 90,000 miles on it. I use Citgo 91 octane when I can get it. That gas has MTBE in it which can't be good for performance.

I hope this helps. Feel free to ask more questions or email me at donmartin29@hotmail.com
 
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wulf

Guest
2.59 gear ratio performance?

Hi Don,

thanks for your data - it seems that my LT1 shifts at higher speed so that I most likely have to handle the 2.59 gear ratio. Does anybody out here know what to expect from the standard gear ratio in terms of 0-60 mph, 1/4 mile, top speed?

Wulf
 
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wulf

Guest
manually taken acceleration data?

Don,


else - have you ever tried to stop your times manually with a watch? Thats the only way I can do it yet. What are the erreors I have to expect from this? Did you run comparisons to the equippment you use?

Wulf
 
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wulf

Guest
Hi Don,

I am Wulf - do you remember my name from the LT1 performance thread?
You offered me to contact you directly ...

I have meanwhile checked my gear ratio via speed:

My LT1 goes 140 mph in OD at 4000 rpm so it must be a 3.07 gear ratio.
Thus, we must have comparable 1992 LT1's.

However, I still do not get it: my best time to 60 mph was 6.6 s and
the acceleration to 100 mph needs 15.3 s. Both values are below that what
should be possible. On the other hand, I can go around 160 mph if our Autobahn
allows to do so ... so the engine should be ok. Also the car feels stong, but
ok, I have no useful comparison! By the way I use 95 octane gas.

This all brings me back to a few questions:

1. I take the time by hand using the speedometer. How accurate is this? I found
that the speedometer still shows 8 mph after a fast stop after my Vette was
already standing still - does this mean I make a greater error due to the
damped speedometer, or in other words the speedometer is too slow to follow
the cars acceleration correctly possibly accounting for a one second difference?
2. What is your experience with the G-tech equippement in comparison to hand taken
values with the cars speedometer? Have you ever tried to take the times by hand?
3. If I switch ASR off, I have excessive wheel spin, if I decrease throttle then
a little bit, then the tranny switches to 2nd or third and my effort is wasted
... what can I do to improve that? You wrote that even times to 60 mph below
5 s are possible in optimum cases how can I improve things.
4. With ASR on, some wheelspin (1 turn or so) remains and then my vette goes off
quite well. However, I believe the regulation process of the ASR needs a second
or so to handle that which again decreases the times to 60 mph. Did you also check
your times with ASR on? (my tires are stock tires about 5 years old)
5. I think my times to 100 are closer to that what is possible since I found one
test rport from Road&Track in which a time of 14.1 to 97.4 mph was stated (also
with 3.07 gear ratio and 4 speed auto). This is not too far away from my 15.3 s
value ...
6. Where can I buy the G-tech equippement you use and what is the price?

Don, it would be really great if you would take some time to answer my questions:
its rare to find an experienced driver with seemingly identical car ...

Wulf
 

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