Is this how a stock '96 LT1 acts?
04-22-2014, 06:59 PM
#1
Racer
Thread Starter
Is this how a stock '96 LT1 acts?
At the risk of ridicule, I'll ask whether it sounds like this is a stock '96 LT1. (Apologies in advance for the lengthy read.)
What I heard about the car:
Seller listed it as 156k miles, had been in a front end accident. Had a "rebuilt" title (supposedly distinct from a "salvage" title). It was a remote purchase, the seller hadn't had it that long (about a year), didn't know much else about its history, hadn't driven it much. CarFax said it couldn't find any record of the car. It was cheap, so I took a chance and bought it.
What I know of the car:
'96 base coupe, A4, LT1, odometer showed just under 124k when I got it in January. PCM has a "Rebuilt by GM" decal on it (I assume that is consistent with the front end accident story and the difference between the advertised mileage and the odometer mileage).
The mufflers aren't factory, but I have no idea what they are. The pipes and mufflers are stainless.
It has a Granatelli MAF. (A search here didn't yield many complimentary posts about this product - okay, I didn't find any complimentary posts about it...)
The rest of the car looks untouched (although a bit rough) from what I can tell.
My experience:
I hadn't driven it 100 miles before the water pump started leaking (it may have been leaking before, but it started leaking enough to wet down the belt). I got a new WP and 180 degree thermostat and installed them. Also did spark plugs and wires while I was at it. The passenger side valve cover was leaking, so replaced that gasket and the underside was very clean (no sludge/varnish deposits, looked like stock rockers). After that, I noticed that the radiator fans were coming on, even though the car wasn't getting that hot, but it was running about 20 degrees warmer than it was before the WP started leaking. Not being too familiar with the details of LT1 behavior, I assumed the new thermostat wasn't working properly, so I got another one like it. It brought the temp down a little, but the fans still came on, even cruising in cool weather (40 degrees). I watched the digital readout and determined the fans were coming on high at about 190 degrees. The temp would settle in at about 195. I inquired here, and was told that wasn't the factory "on" temp. I found the original thermostat I had removed, put it back in, and now it cruises at 175-180, and the fans won't come on unless I'm sitting in traffic.
Now, what really got me to wondering is when I got on it and watched the tach last week. I was doing a left turn onto a freeway on-ramp, it had shifted to 2nd before I completed the turn, when I was straightened out I gave it some gas (not quite floored) and it shifted down to first, and stayed there until the tach was at 6000 RPMs. It was pulling hard the whole time. I assume it still has the stock 2.59 gears, as I was doing 60 mph by that time. I don't know where it shifts 2-3, because I simply haven't had it up to that speed. I've done something similar a couple of times since, the tach needle is into the hash marks before it starts the shift 1-2, and is over 6k before completing the shift.
The stall seems to be stock (~1500). When warmed up and idling in gear, it has just a little bit of "attitude" (which is why I changed the plugs and wires - thought it had a bit of a miss, but didn't change with the new parts). It passed our dyno emissions test with flying colors (posted the results in another thread). I've heard talk of the great low-end torque LT1s have, but frankly my first impression was it's a bit lazy, and as I'm getting more familiar with it and am willing to get on it, it seems to really come on at about 2500 RPMs.
So, apparently it's got a cooler than stock thermostat, cooler than stock fan settings, aftermarket MAF, aftermarket mufflers. Have the shift points been modified? Is this something other than a stock cam?
The first weekend of May, I plan on taking it to the track. Talking to a tech guy weekend before last when I got it inspected, who said he's got a similar car and is familiar with how they run, he said it should run low 15's at our 5800' elevation track (that's equivalent to low 14's at sea level - divide your sea level ET by .94, that's what you'd run up here). Guess we'll see.
What I heard about the car:
Seller listed it as 156k miles, had been in a front end accident. Had a "rebuilt" title (supposedly distinct from a "salvage" title). It was a remote purchase, the seller hadn't had it that long (about a year), didn't know much else about its history, hadn't driven it much. CarFax said it couldn't find any record of the car. It was cheap, so I took a chance and bought it.
What I know of the car:
'96 base coupe, A4, LT1, odometer showed just under 124k when I got it in January. PCM has a "Rebuilt by GM" decal on it (I assume that is consistent with the front end accident story and the difference between the advertised mileage and the odometer mileage).
The mufflers aren't factory, but I have no idea what they are. The pipes and mufflers are stainless.
It has a Granatelli MAF. (A search here didn't yield many complimentary posts about this product - okay, I didn't find any complimentary posts about it...)
The rest of the car looks untouched (although a bit rough) from what I can tell.
My experience:
I hadn't driven it 100 miles before the water pump started leaking (it may have been leaking before, but it started leaking enough to wet down the belt). I got a new WP and 180 degree thermostat and installed them. Also did spark plugs and wires while I was at it. The passenger side valve cover was leaking, so replaced that gasket and the underside was very clean (no sludge/varnish deposits, looked like stock rockers). After that, I noticed that the radiator fans were coming on, even though the car wasn't getting that hot, but it was running about 20 degrees warmer than it was before the WP started leaking. Not being too familiar with the details of LT1 behavior, I assumed the new thermostat wasn't working properly, so I got another one like it. It brought the temp down a little, but the fans still came on, even cruising in cool weather (40 degrees). I watched the digital readout and determined the fans were coming on high at about 190 degrees. The temp would settle in at about 195. I inquired here, and was told that wasn't the factory "on" temp. I found the original thermostat I had removed, put it back in, and now it cruises at 175-180, and the fans won't come on unless I'm sitting in traffic.
Now, what really got me to wondering is when I got on it and watched the tach last week. I was doing a left turn onto a freeway on-ramp, it had shifted to 2nd before I completed the turn, when I was straightened out I gave it some gas (not quite floored) and it shifted down to first, and stayed there until the tach was at 6000 RPMs. It was pulling hard the whole time. I assume it still has the stock 2.59 gears, as I was doing 60 mph by that time. I don't know where it shifts 2-3, because I simply haven't had it up to that speed. I've done something similar a couple of times since, the tach needle is into the hash marks before it starts the shift 1-2, and is over 6k before completing the shift.
The stall seems to be stock (~1500). When warmed up and idling in gear, it has just a little bit of "attitude" (which is why I changed the plugs and wires - thought it had a bit of a miss, but didn't change with the new parts). It passed our dyno emissions test with flying colors (posted the results in another thread). I've heard talk of the great low-end torque LT1s have, but frankly my first impression was it's a bit lazy, and as I'm getting more familiar with it and am willing to get on it, it seems to really come on at about 2500 RPMs.
So, apparently it's got a cooler than stock thermostat, cooler than stock fan settings, aftermarket MAF, aftermarket mufflers. Have the shift points been modified? Is this something other than a stock cam?
The first weekend of May, I plan on taking it to the track. Talking to a tech guy weekend before last when I got it inspected, who said he's got a similar car and is familiar with how they run, he said it should run low 15's at our 5800' elevation track (that's equivalent to low 14's at sea level - divide your sea level ET by .94, that's what you'd run up here). Guess we'll see.
04-22-2014, 07:07 PM
#2
I can't comment on the shifting thing, but I thought redline on those cars is 5800 RPMs? It should have shifted by then.
And also LT1s are known for their high end horsepower, the L98s are known for the low end torque.
You mentioned that the water pump was leaking, typically when they leak, the Optispark gets wet and shortly after fails. I'd keep an eye on that. It may be where that roughness at idle is coming from.
And also LT1s are known for their high end horsepower, the L98s are known for the low end torque.
You mentioned that the water pump was leaking, typically when they leak, the Optispark gets wet and shortly after fails. I'd keep an eye on that. It may be where that roughness at idle is coming from.
04-22-2014, 07:23 PM
#3
Le Mans Master
It seems like the transmission is shifting oddly. While I can't speak for the '96 auto, I believe it is basically the same trans that was in my '98 Z28. So, with little info on the car it is really hard to tell. The shift points could have been changed, it could have a vacuum issue, or is need of a cable adjustment.
The '95/'96 optisparks were alot less vunerable to the dreaded waterpump leak. My opti survived not only that, but an upper rad hose burst a few years later. However, if it is indeed the original opti, a cap and rotor change might in order.
The '95/'96 optisparks were alot less vunerable to the dreaded waterpump leak. My opti survived not only that, but an upper rad hose burst a few years later. However, if it is indeed the original opti, a cap and rotor change might in order.
04-22-2014, 07:31 PM
#4
Racer
Thread Starter
I actually planned on changing the Opti, but was having trouble getting the damper pulley off. I was running out of time on my temporary plates to get the emissions test done, so I put the pulley bolts back in and took my chances (relying somewhat on the fact that it was a '96). It seems to run fine, and I've put almost 1k miles on it since then.
I have HP Tuners (guess I should have mentioned that), I should try to download the PCM file and see where the settings are. I think I can do that without spending credits (used up my original 8, bought 2 more for the '57, didn't want to have to buy another 2 right now).
I have HP Tuners (guess I should have mentioned that), I should try to download the PCM file and see where the settings are. I think I can do that without spending credits (used up my original 8, bought 2 more for the '57, didn't want to have to buy another 2 right now).
05-03-2014, 12:30 PM
#5
Racer
Thread Starter
I took it to the track last night. A fairly nice night for racing, density altitude was in the 7700' range, wind wasn't much of a factor.
First pass was a 14.777 @ 96.66 MPH with a 2.248 60'. That was my only time trial, then had to go straight into eliminations (I got to the track late, and was running the '57 for the first time since its LS swap as well).
It wandered around that ET during eliminations, I made it to the 6th round (quarter finals - it's a pretty popular race), when a kid put a .023 package on me (a Pontiac GTP, who dialed quicker than me). That was at 11:20 pm, I ran it out because he was still ahead of me, it ran a 14.697 @ 97.43 MPH.
To put that into sea level perspective: The NHRA has correction factors for our altitude. The Stock/Super Stock ET factor is .9405, and MPH is 1.0563, to convert altitude times to sea level times (in my experience, I have found them to be pretty close). So, the 14.697 would be 13.822, and the 97.43 would be 102.91. To see what your car would do up here, take your sea level times/speeds and divide by those numbers.
The 60' is pretty lazy, obviously. 2.59 gears and stock stall mean it takes awhile to build up a head of steam. But, once it does, it pulls hard to the shift point. I was going through the traps in 2nd gear.
So, from all I hear, this is not what you would expect from a stock '96. While waiting in the staging lanes for the first time trial, a gal with a '94 coupe was right behind me, and I spent some time chatting with her. She said she's had the car for 3 years, it's another "rescue" vehicle like mine, all stock, and has run consistent 15.0's the whole time she's had it. After I made my pass, she came by my pit and congratulated me on the good ET.
Some day I may find out what cam this car has in it, but for now, it would appear from my limited database that it's something more than a stock '96.
First pass was a 14.777 @ 96.66 MPH with a 2.248 60'. That was my only time trial, then had to go straight into eliminations (I got to the track late, and was running the '57 for the first time since its LS swap as well).
It wandered around that ET during eliminations, I made it to the 6th round (quarter finals - it's a pretty popular race), when a kid put a .023 package on me (a Pontiac GTP, who dialed quicker than me). That was at 11:20 pm, I ran it out because he was still ahead of me, it ran a 14.697 @ 97.43 MPH.
To put that into sea level perspective: The NHRA has correction factors for our altitude. The Stock/Super Stock ET factor is .9405, and MPH is 1.0563, to convert altitude times to sea level times (in my experience, I have found them to be pretty close). So, the 14.697 would be 13.822, and the 97.43 would be 102.91. To see what your car would do up here, take your sea level times/speeds and divide by those numbers.
The 60' is pretty lazy, obviously. 2.59 gears and stock stall mean it takes awhile to build up a head of steam. But, once it does, it pulls hard to the shift point. I was going through the traps in 2nd gear.
So, from all I hear, this is not what you would expect from a stock '96. While waiting in the staging lanes for the first time trial, a gal with a '94 coupe was right behind me, and I spent some time chatting with her. She said she's had the car for 3 years, it's another "rescue" vehicle like mine, all stock, and has run consistent 15.0's the whole time she's had it. After I made my pass, she came by my pit and congratulated me on the good ET.
Some day I may find out what cam this car has in it, but for now, it would appear from my limited database that it's something more than a stock '96.
05-03-2014, 12:52 PM
#6
Team Owner
Member Since: Oct 2004
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St. Jude Donor '05
Times sound inline. Those 2.59 gears are killin ya
A 3.54 gear would wake it up and still have reasonable cruising speed/mpg;then work on the 60 ft times
A 3.54 gear would wake it up and still have reasonable cruising speed/mpg;then work on the 60 ft times
05-03-2014, 01:41 PM
#7
96 auto is a 4l60E your shifting point are into the tune,since the ECM controlls shifting point,old th700r4/4l60s were cable controlled (TV cable and governor).Your 1/4 times are in line with a stock lt1,even a 230 hp TPI car is in the mid 14s,a 300 hp 96 Lt1 is in the low 14s,even high 13s
http://www.corvetteactioncenter.com/...96/96perf.html
http://www.corvetteactioncenter.com/...96/96perf.html
Last edited by tunedport85inject; 05-03-2014 at 01:51 PM.
05-03-2014, 02:05 PM
#8
Racer
Thread Starter
The OBDII 4L60E is one of the reasons I went for this car. I've done some playing around with the tune in my LS1/4L60E swapped '82 Camaro, and wanted to build on that with this car. So far I haven't even downloaded the file, but now that the '57 is running, I should have more time to do that.
05-03-2014, 09:43 PM
#9
Team Owner
Pro Mechanic
My stocker (M6/3.45 gear) has gone 13.75 here in UT. I'm a little lower than you at 4500', but our DA is typically between 7-9000', for some reason. However, mid 14's are very typical of stock or stockish LT1's at this elevation. READ THIS THREAD for evidence of that from other drag track savvy locals and it's kind of funny too.
As for your 1>2 shift point, either something has been modified or your tach is off. Cut off it is at precisely 5850 so if you're showing 6k on the tach...well, it shouldn't go there. Also, mine isn't "pulling hard" by 5800, IMO. It hasn't fallen on it's face by any means, but it's definitely fading.
I'd be inclined to wonder if you're car has some other mods (cam?) based on your DESCRIPTION of how it runs (idle, high end pull), but then your traps....they don't back that up IMO. I trap 100-101, and it put down 277 and 278 on a Dyno jet each pull a year apart.
Last edited by Tom400CFI; 05-03-2014 at 09:48 PM.
05-04-2014, 01:40 AM
#10
Racer
Thread Starter
I'll try to do some datalogging the next time I'm at the track to see exactly what it's doing. Also intend to read the file to see if anything interesting jumps out.
But, another issue to address first. Today I put it in reverse to back out of the garage, thought I heard a snapping sound as it engaged. Put it back in park, turned the radio off, tried it again, no noise but the car didn't want to move. Acts like a brake is dragging. I just shut it off and took another car for that trip, probably won't get a chance to look at it for a few days.
But, another issue to address first. Today I put it in reverse to back out of the garage, thought I heard a snapping sound as it engaged. Put it back in park, turned the radio off, tried it again, no noise but the car didn't want to move. Acts like a brake is dragging. I just shut it off and took another car for that trip, probably won't get a chance to look at it for a few days.
05-04-2014, 08:01 AM
#11
Le Mans Master
The ideal gear IMO would be a 3.73. But speaking on a practical, common sense upgrade. I would find a dana 44, 3.45 and convert. 3.45 is what the majority of them had. You need the driveshaft, batwing, and the center chunk. Everything else is the same.
That single change really wakes up the LT1. FWIW mine, when it was stock with a 3.54 gear would run 13.2x at 105.xx on a good day. With a 3000 stall converter it dropped to 12.91 et. 1.7x 60 ft. on street tires.
On the t-stat, did you get a LT1-4 specific t-stat? They are different then the SBC stats.
Also, the 6000 rpm you are seeing could just be the tach is off.
As far as factory programming goes, I think the shift was supposed to be at 5750, and rev limiter was set at 5850. If everything is stock on the car, I would try lowering the shift point to 5750 and it may be quicker then 6000, of course this is all assuming it really is pulling 6000 rpms.
That single change really wakes up the LT1. FWIW mine, when it was stock with a 3.54 gear would run 13.2x at 105.xx on a good day. With a 3000 stall converter it dropped to 12.91 et. 1.7x 60 ft. on street tires.
On the t-stat, did you get a LT1-4 specific t-stat? They are different then the SBC stats.
Also, the 6000 rpm you are seeing could just be the tach is off.
As far as factory programming goes, I think the shift was supposed to be at 5750, and rev limiter was set at 5850. If everything is stock on the car, I would try lowering the shift point to 5750 and it may be quicker then 6000, of course this is all assuming it really is pulling 6000 rpms.
05-05-2014, 07:35 PM
#12
Racer
Thread Starter
The ideal gear IMO would be a 3.73. But speaking on a practical, common sense upgrade. I would find a dana 44, 3.45 and convert. 3.45 is what the majority of them had. You need the driveshaft, batwing, and the center chunk. Everything else is the same.
That single change really wakes up the LT1. FWIW mine, when it was stock with a 3.54 gear would run 13.2x at 105.xx on a good day. With a 3000 stall converter it dropped to 12.91 et. 1.7x 60 ft. on street tires.
That single change really wakes up the LT1. FWIW mine, when it was stock with a 3.54 gear would run 13.2x at 105.xx on a good day. With a 3000 stall converter it dropped to 12.91 et. 1.7x 60 ft. on street tires.
For the time being I'm running in a class that is 14.00-up dial-in, so I don't want to make it too quick...
Considered that. Need to data log to confirm.
As far as factory programming goes, I think the shift was supposed to be at 5750, and rev limiter was set at 5850. If everything is stock on the car, I would try lowering the shift point to 5750 and it may be quicker then 6000, of course this is all assuming it really is pulling 6000 rpms.
05-05-2014, 08:22 PM
#13
Racer
I am not sure if the LT1 uses the same fan switch as my car, but you may have the aftermarket fan switch (lower temp) installed. Mine on my 1988 L98 is located on the driver side head after the #1 plug.
I purchased mine from Corvette Central and it turned the fans on at 190 and the car ran at the same temp as your car with the same 180 t-stat.
I purchased mine from Corvette Central and it turned the fans on at 190 and the car ran at the same temp as your car with the same 180 t-stat.
05-05-2014, 08:51 PM
#14
Racer
Thread Starter
I am not sure if the LT1 uses the same fan switch as my car, but you may have the aftermarket fan switch (lower temp) installed. Mine on my 1988 L98 is located on the driver side head after the #1 plug.
I purchased mine from Corvette Central and it turned the fans on at 190 and the car ran at the same temp as your car with the same 180 t-stat.
I purchased mine from Corvette Central and it turned the fans on at 190 and the car ran at the same temp as your car with the same 180 t-stat.
(Thank you for your service. I was stationed at Fort Carson in '77-'78, and for 6 months in '82. Ever make it to Bandimere?)
05-06-2014, 07:35 AM
#15
Le Mans Master
here is a picture of the LT1 style thermostat. http://www.ebay.com/itm/HYPERTECH-1008-Thermostat-1992-1993-Chevrolet-LT1-engines-Power-Stat-/400692963779?pt=Motors_Car_Truck_Parts_Accessories&hash=item5d4b2969c3&vxp=mtr
05-06-2014, 10:21 AM
#17
Racer
05-06-2014, 04:37 PM
#19
Racer
I just purchased a 383 Stroker short block from a fella up your way near Evergreen. He has a very good selection of Corvettes and parts including a ZR1 that he races there too.
05-07-2014, 09:07 PM
#20
Safety Car
Your times are right where they should be for a LT1 Auto. The 2.59 cars are lazy but run ok for what they are. They definitely do NOT have the giddy up a LT1 3:45 equipped ZF6 car has.