: How are you shifting to get good times in the 1/4mi?



Vrocks
10-24-05, 02:28 PM
I'm thinking about taking my V to the track (1/4mi) in the next couple of weeks. To get a time around 13.4 do I need to power shift? When I'm driving my V on public roads I rev it out before all of my shifts i.e. 1st, 2nd and 3rd and sometimes I'll barely touch the limiter. Will this give me maximum performance or should I short shift to 2nd gear, @ around 6,000rpm?

Also, I've specualted that my V might have a weaker LS6 because I almost never have hop or wheel spin (once I'm rolling), even on near drop clutch shifts from 1st to 2nd @ red line. So my trap speeds should confirm this.

I'm going to run a mixture of 93 and 100 when I go, trying to get around 97 octane, and I'll prbably make 3 runs. The only thing that'll ruin my night would be a blown diff, especially since this one has been perfect. Well, if I don't make it into the 14's... that'll ruin my night as well.

StealthV
10-24-05, 02:46 PM
From the fuel side, 93 octane is good enough for a mostly stock engine; especially with the cooler temperatures this time of year.

Vrocks
10-24-05, 02:57 PM
From the fuel side, 93 octane is good enough for a mostly stock engine; especially with the cooler temperatures this time of year.
:lildevil:
I know, I just want to run some race gas and not worry about any timing being pulled. I figured this way I'll know the engine should be running with full factory timing.
The car did run smoother and stronger when I mixed in some 100. The mixture only took me to around 96 octane, and it felt about the same as Sunoco Ultra 94, which definitely feels better than the 93 Mobil that I usually get. I'm actually going to switch to Sunoco for the 94 and because all of the Mobil's in my area are changing to Luk Oil.

Forgot to mention that I'll be running on Mud and Snow tires from Dunlop (winter sport M3's). :thepan: Which should help the diff.

Vrocks
10-24-05, 03:20 PM
Ok, I guess it was a dumb question but I wanted to get some discussion going.

Also, if anyone in the PA, DE or NJ (close enough to the tri-state area) wants to meet at a nearby track I'll do it. If it's just me I'll post some pics of the time slips and let you know how the car's doing after the racing.

Joey'sVee
10-24-05, 03:35 PM
I want to go to the track also. I'm going to wait till I can get the headers, cats and a Stealth tune. I think what I will do is launch at about 3000 rpms then redline each shift from there on. Is this correct guys?????

L.Sanchez
10-24-05, 03:37 PM
The powerbands of the LS6 are higher up there rev range. Bang the next gear as you come close to that rev limiter to keep the gearing in the fat part of the powerband. No mercy! :)

-Ladis

HDMLNIUM
10-24-05, 03:58 PM
When I am racing the 1/4 mile I like to powershift (Full throttle shifts, just pop the clutch while you grab another gear) Faster than most automatics.. lol And I try to shift between 6800 to 6900 rpm's.
You mentioned NJ, why not go this Sat, the 29th.. I am going to make the 400 mile trip to run with the best at Englishtown against the SRT8 crowd. Someone has to give them a run for their money right...
Rick, I will send you an e-mail tonight, maybe a new tune and anything else you want to send my way by Thursday so I can get it on Thursday night. I am going to put my BMR awk back on and am also looking to support the diff again, any way better than the BMR way or just through that back on again too??
We want them to be afraid of the Stealth-V powered V's.....
Be very afraid........:lildevil:

Bill

Vrocks
10-24-05, 04:07 PM
Damn, 400 miles to get on a good track? Maybe some day but I want to see how it goes on a local track.

-update-
I just saw that you're driving from Maine.... How far is Englishtown from Philly?

I was thinking more like a 45 minute drive. I can't remember the name of the track that I got from the NHRA's web site (I also checked the IHRA) but it's not to far from Philly (I'm about 30 minutes away), the other PA tracks were closer to Harrisburgh and Pittsburgh.

HDMLNIUM
10-24-05, 04:22 PM
257 miles and 4 hours if you drive with traffic..
Easy little trip to have joined in something fun..
Bill
http://imgs.maps.yahoo.com/overviewmap?OVMAPDATA=sBhIVOR32XXVEKEKhHOJfyw4wugm zreesYeA5uZLSqTiA.IAxM_QsdN_5tIY15FMnhPix3kTD4mLoW 5zVLiTOYyqB.lIhgqiTYRiYNIvDaWqdxKMLrDBQ67CJss-&ORG=a7YTovMmhn0aHTK0o3BRO8WfaYr5wLqiwN.Pe95lcfi7vk uTWvMXCd6LaGTcqhBj.KXwttKysFJB_81fPhq7A4tTMzcdvol1 a9jC4ULdDiE7SERyibYb75zjk_Y-

Vrocks
10-24-05, 04:47 PM
257 miles and 4 hours if you drive with traffic..
Easy little trip to have joined in something fun..
Bill
http://imgs.maps.yahoo.com/overviewmap?OVMAPDATA=sBhIVOR32XXVEKEKhHOJfyw4wugm zreesYeA5uZLSqTiA.IAxM_QsdN_5tIY15FMnhPix3kTD4mLoW 5zVLiTOYyqB.lIhgqiTYRiYNIvDaWqdxKMLrDBQ67CJss-&ORG=a7YTovMmhn0aHTK0o3BRO8WfaYr5wLqiwN.Pe95lcfi7vk uTWvMXCd6LaGTcqhBj.KXwttKysFJB_81fPhq7A4tTMzcdvol1 a9jC4ULdDiE7SERyibYb75zjk_Y-
I'd like to go but that's to many miles on a V that's already past the lease terms. I had the 2 year 12K mile lease and I'm already over 24K (won't be out of the car until late Dec or Jan at the earliest).

I actually figured out that I'm paying twice as much for my fuel because of the $.20 per mile over penalty:

(2.99 per gallon of 93) / (16.7 mpg) = about $.18 per mile
+
Penalty of $.20 per mile
=
$.38 per mile or about $6.35 per mile!

That's like filling the tank up with race gas :rant2: . I don't want to sound cheap, just thought it was an interesting way to look at it. If things go well I'll make a future trip to Englishtown or another big name track. By then I'll be driving an '06 CTS-V or the STS-V.

HDMLNIUM
10-24-05, 05:04 PM
No problem, I can't blame you there.. I will try to help represent us V's the best that I can, I have some wrenching to do this week in my spare time if I get any.. lol
I am going to trailer the V down, just incase I launch a little to hard and she breaks.. Don't want a 4oo mile tow bill thats for sure.. See now we both sound cheap... haha:histeric: :thumbsup:

Bill

Luna.
10-24-05, 06:18 PM
I'm thinking about taking my V to the track (1/4mi) in the next couple of weeks. To get a time around 13.4 do I need to power shift? When I'm driving my V on public roads I rev it out before all of my shifts i.e. 1st, 2nd and 3rd and sometimes I'll barely touch the limiter. Will this give me maximum performance or should I short shift to 2nd gear, @ around 6,000rpm?

I thought there was a thread/analysis around here that discussed exactly this. It seems to suggest that you want to hold off shifting for a long as possible (i.e. don't short shift). Granted, I believe that was with the stock car, with the stock powerband, but I highly doubt a more powerful version of the car would justify short-shifting.

As far as octane goes, based on what I'm reading at the Corvette boards, it appears that just increasing the octane won't do much good, if at all. Some even suggested that, unless you had a tune to specifically increase the timing, the higher octane fuel might actually decrease power (something related to slower burning, but that doesn't make much sense to me, but whatever...I'm still learning).

GNSCOTT
10-24-05, 08:29 PM
I say shift when you feel the car fall on its face, and that seems to be right around 6200rpms. Torque is what gets you down the track. You want the car pulling its hardest at all times. You shouldn't even have to look at the tach. Practice seeing where it drops on the street, its well before the rev limiter.

DansCTSV
10-24-05, 08:41 PM
I usually launch between 3000 - 3500 rpm's. I ease the clutch out. It takes some practice to get used to how fast you can let the clutch out and give it more gas, balancing loss of traction with too much traction. In which case you will get a slight bog. I shift right about red line, but GNSCOTT is right, it's pretty much by feel. I don't power shift but I do shift fast. I can't bring myself to do that in my V. On a bike is a totally different story. So I let off the gas slightly and shift. It is still very fast. I don't think there is more than a fraction of a tenth to be gained by speed shifting.

Of course 20 run's later and my V is on its way to the dealer for a new rear end...

Vrocks
10-24-05, 09:06 PM
I am going to trailer the V down, just incase I launch a little to hard and she breaks..
Bill
Having a trailer is a good idea and it's something I'll look into if I go to the tracks a lot.

GNSCOTT,
That's what I was thinking. I would feel the fall off but I wasn't sure if the torque multiplication from the gears would offset the drop in power from the engine. I was planning on making three runs because I don't want to destroy the car in one night but I might make a few more (5) just to try a few different launch and shifting techniques.

DansCTSV,
I should be safe if I only make around 3 - 5 runs and have the fluids replaced and analyzed after that. The car has just under 25K miles on it and I haven't replaced the diff fluid yet, so I'm guessing it'll be full of metal when I look at it.

About the Race gas,
I'm only running it to "run it" and because I don't want the engine to pull timing if it gets hot. It was around 50F on the night that I put the 100 in the tank, and after a few short bursts to 100 the engine oil temp was over 240. I aslo think the smell is cool now that I know nothings wrong with the car.

DansCTSV
10-24-05, 09:20 PM
I was not trying to discourage you by telling you about the rear blowing. I think its great that people are taking this car to the drags. It's an awesome car with a weak rear. Hopefully the new STS-V rear will solve the probems, or at least be a mid term solution until an after market rear comes out that can really handle the horse power.

Good luck at the track. Hopefully you will run low 13's!

Also I was running drag radials, so that puts more stress on the diff.

And I agree on the trailer idea. Bad part is that the ride up and back is half the fun. Maybe I will have to get a trailer and before I leave for the track I will hitch it up to my truck. Then if I run into troubles I can call my wife and have her come rescue me...

I was also lucky because a friend of mine that was with me had AAA Plus. It covers 100 miles of towing but you have to be a AAA member for a year before you can get plus. I think you only get 5 tows a year though.

CVP33
10-24-05, 09:24 PM
How am I shifting?

As if I was trying to kill her from the inside out. :lildevil:

StealthV
10-24-05, 09:54 PM
Even though the perceived acceleration drops off at upper rpms, the torque multiplication advantages of lower gears plays a large role. For example, first gear at a given rpm always puts 43% more force to the ground than second. Running to the redline, even though power is dropping off quickly, takes full advantage of the 43%.

As shown in the chart below, first gear (blue diamond curve) is still putting down over 2300 ft-lbs of force at 6500 while the best second gear (magenta square curve) can ever do at any rpm is about 2250. In the graph, think of each colored line as a "dyno curve" in each particular gear.

This acceleration force data collected in the real world on the street isn't accurate to the gnat's ass but does illustrate the advantages of torque multiplication.
http://www.cadillacfaq.com/faq/answers/img/shiftperf.jpg

crowan
10-24-05, 10:00 PM
Normally, I would say, "No guts, no glory." Powershift that puppy. However, the V is not the slickist shifting car in the world and you don't want to waste a run with a missed shift. If the track is busy, you may not get more than three runs. Make the most of them.

You can make up more time with a good launch than you will ever lose in a non-power shift. Put your focus there.

Good luck and kick ass!:want:

CR

globed70
10-25-05, 09:50 AM
Even though the perceived acceleration drops off at upper rpms, the torque multiplication advantages of lower gears plays a large role. For example, first gear at a given rpm always puts 43% more force to the ground than second. Running to the redline, even though power is dropping off quickly, takes full advantage of the 43%.

As shown in the chart below, first gear (blue diamond curve) is still putting down over 2300 ft-lbs of force at 6500 while the best second gear (magenta square curve) can ever do at any rpm is about 2250. In the graph, think of each colored line as a "dyno curve" in each particular gear.

This acceleration force data collected in the real world on the street isn't accurate to the gnat's ass but does illustrate the advantages of torque multiplication.
http://www.cadillacfaq.com/faq/answers/img/shiftperf.jpg

Thank you for saving me the time... facts should always win.

Vrocks
10-25-05, 04:10 PM
I'm going to MAPLE GROVE RACEWAY if they're open this Friday. They have events scheduled around friday the 28th but nothing on the 28th according to their web site.

I'll probably have some video footage both in the car and out of the car. If things go well I'll be able to use this as a base for a comparison with either the '06 CTS-V or STS-V (I'm going to test drive both V's).

Should I cover my VIN or license plate?

MCaesar
10-25-05, 05:53 PM
Even though the perceived acceleration drops off at upper rpms, the torque multiplication advantages of lower gears plays a large role. For example, first gear at a given rpm always puts 43% more force to the ground than second. Running to the redline, even though power is dropping off quickly, takes full advantage of the 43%.

As shown in the chart below, first gear (blue diamond curve) is still putting down over 2300 ft-lbs of force at 6500 while the best second gear (magenta square curve) can ever do at any rpm is about 2250. In the graph, think of each colored line as a "dyno curve" in each particular gear.

This acceleration force data collected in the real world on the street isn't accurate to the gnat's ass but does illustrate the advantages of torque multiplication.
http://www.cadillacfaq.com/faq/answers/img/shiftperf.jpg

That is an outstanding graph. However, don't forget that for people who don't power shift there is a slight delay between when they intend to reach for the next gear and when they actually complete the change. IOW, if you want to shift at 7200rpm then some folks need to start grabbing around 6800

slow35th
10-25-05, 06:01 PM
IOW, if you want to shift at 7200rpm then some folks need to start grabbing around 6800

And have the rev limiter raised. :lildevil:

CVP33
10-25-05, 07:09 PM
A little birdie told my that the LS6 pulls strong up to nearly 8,000 rpms. But you're risking everything by doing that. If you get a StealthV tune you're already blowing through the rev range so quickly I swear I bang the rev limiter more with the tune than without even with a higher limit.

GNSCOTT
10-25-05, 09:43 PM
A little birdie told my that the LS6 pulls strong up to nearly 8,000 rpms. But you're risking everything by doing that. If you get a StealthV tune you're already blowing through the rev range so quickly I swear I bang the rev limiter more with the tune than without even with a higher limit.

I think the little birdie is wrong. Max HP is at 6000rpm's and it drops from there. I know just before I hit the rev limiter the front end starts taking a nose dive. They may have meant that it can handle 8000rpm's with the right cam in it, or that you can actually rev the car that high, but the power will not be there (of course IMHO).

Vrocks
10-27-05, 02:33 PM
Maple Grove isn't open this Friday. The earliest that I can go is next Saturday Nov 5th, and they're only open for a few hours. :burn: