C4 LT 1 vs CTS LS7?
04-11-2015, 07:51 AM
#21
Safety Car
LOTS of misinformation in this thread. Caddy is LS6. Caddy is 3800 lbs, so at most, it's ~550 lbs more than a C4. Caddy motor is superior; 400 hp/ 395 lb-ft, to the LT1's 300 hp/340 tq, but the Caddy trans is inferior, and the rear suspension is horrible for drag-track type starts.
IDK why these treads exist/ Data is readily available.
MT, 13.1 @110
C&D 13.2@109
LT1 car will go that low ET....it would be hard pressed to get one to trap 110 though.
I own both; a '92 LT1 and an '05 CTS-V. If I had to pick a car for the strip I'd pick the 'Vette every day of the week and twice on Sundays. Why? The V is horribly handicapped by a piece-of-cow-dung shifter, and unbelievably horrible WHEEL HOP. While the car mags got the number they did out of cars they don't care about, there is no way in hell I would:
*Warm/clean tires
*Launch 100%
*Flat foot shift
...in the Caddy. IT WILL BREAK...especially w/the weak early model rear diff. I would roll out of the start, floor it, then granny shift as quickly as they synchros allow (not that quick in our car).
A race between the 'C4 LT1 and the CTS-v would be a driver's race....but the 'Vette can take it over and over and over again, and the Caddy can't. So in answer to this:...it ALL depends on driver ability, and how much the Caddy driver is willing to risk.
.
IDK why these treads exist/ Data is readily available.
MT, 13.1 @110
C&D 13.2@109
LT1 car will go that low ET....it would be hard pressed to get one to trap 110 though.
I own both; a '92 LT1 and an '05 CTS-V. If I had to pick a car for the strip I'd pick the 'Vette every day of the week and twice on Sundays. Why? The V is horribly handicapped by a piece-of-cow-dung shifter, and unbelievably horrible WHEEL HOP. While the car mags got the number they did out of cars they don't care about, there is no way in hell I would:
*Warm/clean tires
*Launch 100%
*Flat foot shift
...in the Caddy. IT WILL BREAK...especially w/the weak early model rear diff. I would roll out of the start, floor it, then granny shift as quickly as they synchros allow (not that quick in our car).
A race between the 'C4 LT1 and the CTS-v would be a driver's race....but the 'Vette can take it over and over and over again, and the Caddy can't. So in answer to this:...it ALL depends on driver ability, and how much the Caddy driver is willing to risk.
.
People don't understand that having a fast car is one thing, having one both fast and RELIABLE is another. The Corvette can take punishment, a GOOD driver, is fast and STILL does not BEAT on the car.
I'd run a Stock CTS-V LS6/LS2 car at the strip with my 93 LT1 ZF6. It would be a driver race. I'll kill the guy off the line, and races are mostly won and lost in the first 60 feet. I can pull 1.9X 60' times on street tires, you WON'T on the Caddy, unless you want to go home on a trailer. My Corvette...."thank you sir, may I have another" all day long, no complaints or issues.
The Caddy is faster on paper, but in the real world you can throw that away, too many variables. They are close enough on paper to be interesting in a race.
Last edited by 93Rubie; 04-11-2015 at 08:00 AM.
04-11-2015, 07:57 AM
#22
Safety Car
I've tried NOT shifting into 3rd and I hit the rev limiter WAY before the traps. I cannot begin to tell you how that hurts an ET.
Funny, I'm typically going about 105 which according to your data means I need 4th.
FYI, I'm also launching the crap out of the car. 1.9X 60' times on street tires. ZF6 as well. An auto would never see 4th I support that argument.
Personal best is a 13.38@105. I've ran a slew of 13.4's and sub 2.0 60' times. Car isn't setup for drag racing either, its setup for SCCA B Street auto-x. Which means NO power mods or gear mods or just about anything that would make it faster in a straight line. Actually all the rear camber and Koni shocks probably hurt me. The sticky Dunlop ZII's don't however.
04-11-2015, 11:12 AM
#23
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That's not true at all. How did you come to that conclusion? I hit 4th every pass in my LT1, and that is here at high elevation where I'm not even trapping what I would at sea level.
Same in the 'V. 3.73 rear in the V ensures that you must go to 4th gear or you'll hit the limiter in 3rd before the finish.
Same in the 'V. 3.73 rear in the V ensures that you must go to 4th gear or you'll hit the limiter in 3rd before the finish.
I opted instead to have the limiter bumped up to 7600 to get it the heck out of the way in the 1/4 mile drags. So! Bumping the limiter might keep you away from the loss between gears in a tight (drivers race) contest. Just a thought, thar buddy!
04-11-2015, 11:41 AM
#24
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St. Jude Donor '05
Got the best times out of the Z shifting around 6500
Had once ran a BBC Vega uncorked, couldnt hear my car
Looked at the tach in first it was well over 7300 thought it was going to pop lol
I got walked bad, real bad.
Stock cam in the LT1 is done well before 6k no sense in running it up higher
Had once ran a BBC Vega uncorked, couldnt hear my car
Looked at the tach in first it was well over 7300 thought it was going to pop lol
I got walked bad, real bad.
Stock cam in the LT1 is done well before 6k no sense in running it up higher
04-12-2015, 08:02 AM
#25
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My point is/was: Do whatever works!! If the shift point normally comes near enough to the finish, there may not be time enough to make up for the shift, in spite of an increase in torque. In that case, extending the limiter may be an option (was in my case!), and might be enough to shadow the CTS in a tight race??
Last edited by Paul Workman; 04-12-2015 at 08:08 AM.
04-12-2015, 11:57 AM
#27
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Yeah, boy I don't know... Seems every time our local group of Zs goes to the drags, someone twists off a stock spindle! We DO have a fix (a forged 31 or 33 spline upgrade, if anyone is interested), but it seems it is just a matter of time!
04-12-2015, 09:13 PM
#28
Team Owner
Pro Mechanic
No need to be breaking parts on stock cars, to go fast. C4 'Vettes especially. Driver error.
No short shifting here. I flat foot shift at the highest RPM I can, where I don't hit the limiter during the shift, so I'll clutch-in my shifts at ~5600 or so. I'm trapping ~101 here in SLC, so staying in 3rd and running into the limiter would cut ~7 mph off my trap, and who knows how much ET, more more than I'm willing to sacrifice. 
Have to shift to 4th, or as you mentioned, change the limiter (which I haven't done). Cuisinartvette is right; by the time you get to the stock limiter on a stock LT1, it's fading fast. I think that in a stock LT1, even w/a limiter change, you'd still want to shift. Especially at sea level.
Have to shift to 4th, or as you mentioned, change the limiter (which I haven't done). Cuisinartvette is right; by the time you get to the stock limiter on a stock LT1, it's fading fast. I think that in a stock LT1, even w/a limiter change, you'd still want to shift. Especially at sea level.
04-13-2015, 01:48 PM
#29
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No short shifting here. I flat foot shift at the highest RPM I can, where I don't hit the limiter during the shift, so I'll clutch-in my shifts at ~5600 or so. I'm trapping ~101 here in SLC, so staying in 3rd and running into the limiter would cut ~7 mph off my trap, and who knows how much ET, more more than I'm willing to sacrifice. Have to shift to 4th, or as you mentioned, change the limiter (which I haven't done). Cuisinartvette is right; by the time you get to the stock limiter on a stock LT1, it's fading fast. I think that in a stock LT1, even w/a limiter change, you'd still want to shift. Especially at sea level.
Have to shift to 4th, or as you mentioned, change the limiter (which I haven't done). Cuisinartvette is right; by the time you get to the stock limiter on a stock LT1, it's fading fast. I think that in a stock LT1, even w/a limiter change, you'd still want to shift. Especially at sea level.On paper, a healthy LT1, in combination with flat-shifting may favor the shift to 4th more than a lesser tuned LT1, or lifting for the shift; the distance remaining in spite of the torque increase being the deciding factor.
Just another potato for the stew pot to consider. Time slips will tell the tale, and method may likely depend on the variety of drivers and mechanical situation.
Oh, and as for the spindles... a 4+k rpm input to a dual mass FW, dumped suddenly onto the drive train anchored with hot, Hoosier slicks on a sticky track...it isn't at all certain the little things will survive, time after time after time.
04-13-2015, 03:54 PM
#30
Team Owner
Pro Mechanic
I agree that flat-footing the first two shifts is optimizing your performance (ET) options. However, the lag between shifts is well understood, and lags have to be overcome by the performance after the following shift. So, shifting to 4th vs. not becomes a trade-off between loss for the shift and gain in rear wheel torque in time to make a positive ET difference - not necessarily a "given" for everyone's abilities/LT1, no?
EDIT: What I'm getting at here is this. You got a 400 hp car, 60'ing in what...the 1.8 second range? Or slower? rklessdriver has gone below 1.3 second 60' on stock spindles. So if you're breaking spindles on a C4, and you're 60'ing slower than ~1.3, the reason why is shock to the drive train....dumping the clutch. That is an unnecessary...even lazy technique. A little more finesse with the feet will produce the same or likely better results, while breaking less parts.
.
Last edited by Tom400CFI; 04-13-2015 at 04:12 PM.
04-14-2015, 06:51 AM
#31
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That is all correct. Except in this case we're talking about running into the rev limiter at about 95 mph....at least 7 mph short of a reasonable trap for an LT1. If we were talking about tq curves to the wheel for one gear vs. another and to shift or not, I agree w/your point....time slips would tell the story. But in this case, you would have to be a pretty terrible driver/shifter to go faster by running onto the limiter that early.
I don't see how the state of tune affects the benefits of a flat shift. Some of the energy lost while clutch in, is recouped using a flat shift, regardless of state of tune. Only time I've seen flat shifting be a detriment was in a (my) C6 where each clutch release resulted in massive wheel hop. The C4 isn't handicapped by that annoyance...thankfully.
For sure. That is where a little clutch slippage will go a LONG way. Don't need to DUMP the clutch to get a great launch.
EDIT: What I'm getting at here is this. You got a 400 hp car, 60'ing in what...the 1.8 second range? Or slower? rklessdriver has gone below 1.3 second 60' on stock spindles. So if you're breaking spindles on a C4, and you're 60'ing slower than ~1.3, the reason why is shock to the drive train....dumping the clutch. That is an unnecessary...even lazy technique. A little more finesse with the feet will produce the same or likely better results, while breaking less parts.
.
I don't see how the state of tune affects the benefits of a flat shift. Some of the energy lost while clutch in, is recouped using a flat shift, regardless of state of tune. Only time I've seen flat shifting be a detriment was in a (my) C6 where each clutch release resulted in massive wheel hop. The C4 isn't handicapped by that annoyance...thankfully.
For sure. That is where a little clutch slippage will go a LONG way. Don't need to DUMP the clutch to get a great launch.
EDIT: What I'm getting at here is this. You got a 400 hp car, 60'ing in what...the 1.8 second range? Or slower? rklessdriver has gone below 1.3 second 60' on stock spindles. So if you're breaking spindles on a C4, and you're 60'ing slower than ~1.3, the reason why is shock to the drive train....dumping the clutch. That is an unnecessary...even lazy technique. A little more finesse with the feet will produce the same or likely better results, while breaking less parts.
.
BTW... I envy your 60's What kind of rubber are U using?
And, BTW, in addition to spindles, RAM (& others perhaps) now offer some pretty nifty dual clutch options for C4s (single disc too, in fact) that might be of interest to anyone doing serious time at the 1/4 mi track - especially those of the 383 variety.
04-14-2015, 05:55 PM
#32
Team Owner
Pro Mechanic
Ah, but... One sample (yours) does not a trend make. And, I'm not arguing with you. My point is: IF a driver (leaving you out of it) finds himself less that 150-200 feet from the finish when hitting the rev limiter, shifting isn't likely to be the right, or at least not the ONLY answer. Bumping the rev limiter a couple hundred might just do the trick...as an option. Time slips will tell the tale.
Me? Thanks. I'm currently running 3 year old Bridgstone Potenza RE760 "Sport" tires on C5 Z06 rims; 265 front iIRC, and 295 rear. I don't think my 60's are great....Best I've done w/this car is 1.9 and I can't get lower than that, so far.
04-26-2015, 03:17 PM
#33
Team Owner
Pro Mechanic
Took my V to the strip last Saturday, partly b/c I've always wanted to, partly b/c of this thread.....anyway, things went about exactly as I thought. I couldn't get the Caddy to 60' worth a damn (and I admit, I launched gingerly to avoid rear diff breakage). Best run I made was 14.3/104 on a 2.4 60, so high 13's are certainly attainable with more launching practice and little concern for the rear. Would that beat my LT1? Probably not, as that car has gone 13.75/101. Keep in mind the elevation for both cars.
Obviously the V is running the LT1 down at the end of the 1/4 with a 3 mph advantage, but even if I could get the V's 60 down to 2.0 (doubtful), Car would still be in the 13.8-.9 range. If I could race myself in both cars, it would be fun racing. In the 'Vette b/c I know it won't break, it would win every pass, and in the 'V b/c of that nice top end pull and gaining on the 'Vette from the 1/8 onward. They're both cool cars, but the 'Vette can handle track duty way, way better.
Obviously the V is running the LT1 down at the end of the 1/4 with a 3 mph advantage, but even if I could get the V's 60 down to 2.0 (doubtful), Car would still be in the 13.8-.9 range. If I could race myself in both cars, it would be fun racing. In the 'Vette b/c I know it won't break, it would win every pass, and in the 'V b/c of that nice top end pull and gaining on the 'Vette from the 1/8 onward. They're both cool cars, but the 'Vette can handle track duty way, way better.
