96-speed

iTrader: (19)

What is your routine between runs? Have you guys found any significant differences between letting the car cool down for 15, 30, 45 minutes?

When I go to the track, I run hard. I make about 6 laps within the hour I get to the track, let the car sit for about 15-30min, then make a few more passes before I go home - all hotlaps. Even with my coolant temps around 230 and oil temps around 215 or so, my times don't change noticeably from waiting for the car to sit and cool for 30 minutes :shrug:.

I hotlap 4-5 laps a time. Clutch seems fine, times don't drop, so I keep beating on the car . However, I'm wondering if there is some threshold that I might be outside of. IOW, I may start with the car outside of the threshold, which would explain why there's little difference when I hotlap the car.

FWIW, car is a 01 Z06 with MTI CAI and has run a best of 12.88 @ 112.2 with a 2.09 (yeah, lousy) 60'. That is with a 3000' DA. I'm wondering if trying to get the car cooler woudl give me a little more oomph.

I've also noticed that these cars are extremely sensitive to bogging/60' time. I've recorded a consistent +/- .1 in ET and a solid +/- .5mph for every .05 increase or decrease in 60'. My Camaro wasn't this sensitive. FWIW, It was closer to the .1 at the 60' = .15 at the high end. I find that the C5 doesn't follow that rule. Anyone support or object to this statement?

Ryan

Ranger

500+ passes in two stock C5Zs taught me that the LS6 produces best power with the coolant temp at 190-194 degrees. If you run higher than that, you're giving up power. I kept the coolant temp showing in the DIC and tried to make no passes at a higher temp.

If you're just trying to get your techniques dialed-in, then don't worry about coolant temps and hot-lap the car. But if you're after low ET, then monitor coolant temps like a hawk, or install a fan switch.

Might want to take a read thru the write-up on launch techniques, for which I provide a link in my signature.

Ranger

96-speed

iTrader: (19)

Ranger,

I've read through it a few times. LOL. To be honest, many of my passes are simply 1/8 miles to work on the launch. I'm getting serious bog even at 3500rpms - with a quick/smooth engagement. I need to either slow down the clutch engagement, or launch at a higher rpm. Every launch helps me to "push" the car a little harder. I did the "***** out" technique with my camaro and ended up with no driveshaft or rear end. Oops . Its taking a little time, but improvements are being made. I'm not trying to make any internet list - having too much fun just racing (no dyno racing here!).

Thanks for helping everyone out.

regards,
Ryan

Patman

I agree with Ranger, the LS1 does not need to be cooled down to run it's best, and in fact I've always run my best ETs in my LS1 cars by hotlapping them.

The key is that you don't want to see 220F coolant temps though! I also have found that they like to be at around 190-195F. In my Corvette I have the stock thermo (which is a 177F unit) and I have the fans set to come on much earlier than stock. So when I hot lap, the coolant is usually around 192-196, depending on what the outside temp is.

Most people will find they need to run a 160 thermo in order to have their coolant temps consistently below 200F though. I believe the later LS1s came with a hotter thermostat than my 98 has. So if you want to run your best times, make sure that coolant temp does not go over 200F.

Hotlapping works well because your intake won't get hot (it will heat up fast if you idle it in the pits too long though, or if you shut down the car hot and let it sit for a few minutes) but your oil temps stay hot. If you let the car cool down too long and the oil gets too cold, the engine will make less power.

96-speed

iTrader: (19)

Patman: Do you mind telling me where you have your fan enable temps set (I'm tuning with HPtuners, but I haven't messed with the fan temps yet)? One thing worth mentioning is that I'm logging a consistent 12.2-12.4:1 afr with my wideband during the runs. This logged afr is leaner than it was when the tune was stock. My car seemed to run very rich - sometimes dipping in the 11.9:1 range under WOT. I've made adjustments to lean back it out for next time, which will hopefully be Sunday.

Thanks in advance.
Ryan

REDGAR

Mine likes to be hot lapped. My second pass is usually quicker than first.

Patman

I believe the tuner set fan 1 to come on at around 195F and the high speed fan to kick in around 205F but I'm not 100% sure.

chris.shea

i wait in the lanes with the ac blastin, radio playin... coolant @ 196 when im staged usually 10-15 minutes between passes(outlaws, t&t) and longer on race weekends.

ChiefDave

I too agree with Ranger. Coolant temps much higher then 200 and the car will pull some timing or dump fule on top I think. Maybe a tuner will chime in. Do the hood open cool down between passes and try to get it as cool as you can between oasses and let the entire car cool off and this will help your clutch too. I have found that hot lapping is great for driver's ed (some like me need more of it then most!) not for beter ETs.

An untuned car will be faster 2nd passes and later as the PCM wakes up. I saw a .2 quicker ET pre-tuned.

My car is the same way with the short time, but it does follow the rule .1 loss in short = .2 gain in ET. Are you running OEM SC tires and having the 2.0 short? The SC are awesome but a PIA to launch. GEt some DRs and it makes it so much eaiser. Good luck man!
Dave
PS Come out to a corvette challange and get some passes in and run other vettes. I bet someone would even bring you tires to run, as we have seen just that here in the SC CC

AOC

Yup, same here.

96-speed

iTrader: (19)

Hey guys, I'm running on Firestone Wide Oval tires. They seem to hook pretty decently. I went to the track on Sunday and got more consistent 2.0 short times, along with a new best: 12.78 @ 113.3. The DA was probably close to 3000. I hate to guess, but the temp was the same, and it was very muggy once again. So, that's my best guess.

I did not make any tuning changes this time out. However, I made some fueling changes and changed the fan enable temps once I got home. I'm debating on whether or not to install an u/d pulley. I think I'll wait until I get those consistent 1.9 short times before adding any mods. That's my main goal right now.

To be honest, these Wide Ovals feel like my Camaro did on nitto 555Rs. These C5s seem to have excellent traction out of the box. The SC tires stink, but the IRS is pretty nice!

Ryan

96-speed

iTrader: (19)

Update:

Went to the track last night and made the following changes:

Enabled fans to come on at 205º. Coolant temps were around 205-210 all night vs. 220-230 last time out. I noticed no significant difference.

Secondly, I was able to pull a 1.99 60' and consequently ran my best time of 12.58 @ 112.58. The DA was around 2700-3000'.

On my first few passes, I ran 111mph and my a/f was pretty fat @ 11.5:1 most of the rpm band. I made a few small changes and the next pass the a/f was locked in at 13.0:1. Once again, the effect of this was that my mph jumped to 113.06. Pretty significant! However, my ET never seemed to move on way or the other. The ET was much more dependent of the launch/60', just as I would expect.

In summary, tuning hasn't helped the ET much at all, but the 60' is critical, more than any other car I've driven, for a good ET. One half tenth on the 60' is generally worth two full tenths at the high end. My 2.04 60' = 12.76 and my 1.997 = 12.58.

Good luck to all. Here's a cool shot that the photographer snapped of me - I thought it was pretty cool :




Happy racing. Keep it on the track!
Ryan

mikep2002

iTrader: (10)

I think an A/F reading of 13.0 is a little over the the safety line. I dont let mine run below 11.5 and mine sits now at 11.2 "safety first" Good luck watch your safety factor. I think most tuners dont like it to be over 12

.

I ran 111mph and my a/f was pretty fat @ 11.5:1 most of the rpm band. I made a few small changes and the next pass the a/f was locked in at 13.0:1.

96-speed

iTrader: (19)

Mike,

I've never heard anyone limiting their NA motors to < or = 12.0 a/f (street car/pump gas). Forced induciton, sure, but not NA. From my experience with my past two cars, this holds true - 13.0 is safe.

Also, from a little snooping around, the street a/f can be a little leaner than a dyno a/f and still be safe...roughy .2 or so. IOW, 13.2 on the street ~= 13.0 dyno.

FWIW, the stock tune was anywhere from 11.9-12.4. It just kind of depended on the LTFTs and the weather.

Good luck,
Ryan

Pro Stock John

iTrader: (34)

So how were you launching Ryan? I can't see hotlapping my 02 Z06, I'm sure the clutch fluid willl get too hot.

96-speed

iTrader: (19)

John,

I started launching at 2800 as per Ranger's post, but I just bogged, and bogged, and bogged, and bogged some more. Houston Raceway park is really sticky. My best launch:

4200rpm with a slow release until the tires start grabbing, then I fully engage the clutch and squeeze the throttle. I get a slight bog - 1.997 60'.

I tried a 4200 launch with a quicker release and a wee-bit of tire spin (no bog). However, my 60' went down to 2.04.

Obviously, I think a little more rpm and a quick engagement without any tire spin will help. IMO, the clutch can take it. I slipped the clutch BIGtime on one pass and consequnetly, I felt some slipping in 2nd/3rd gears. So, I let the car sit...for 10 minutes .

FWIW, I'm a crappy driver. It has taken me about 30 passes (4 track visits) to get the sub 2.0 60' - which has been my goal. I need way more practice to get to the 1.8s and keep consistent 1.9s.

I am on fairly new Firestone 295 Wide Ovals.
Ryan

96-speed

iTrader: (19)

New PB after last weekend. With the installation of a pulley, my 01 Z06 with MTI cold air intake, tuning by myself, and stock tires went 12.3 @ 114.98 with a 1.97 60'. Air temp was 76º. I feel confident that I can hit 11.9 once we get those good Texas (-) DAs . Also, raceweight was 3450, which could be cut down 75lbs with less gas and a skipped dessert or two.

Ranger: Do you know what the raceweights of your 01 and 02 Z06s were? Also, did you happen to weigh your CCW wheels separately and compare with the stockers? Just curious.

My stock 01 wheels with new Firestone tires = 53lbs/ea for the rear.

Ryan

Ranger

^^^My bone-stock 01 and 02 Z06s weighted 3090 with 3/8 tank of gas. I weigh 170. So a race weight of 3260. Your estimate of 3450 seems high.

When I wasn't running stock tires, I ran two diff combos:

CCW 17" x 12" wheel weighs 22-23 pound.
BFG Comp TA 315.35.17 weighs 28 pounds

2001 C5Z06 front wheel weighs 19.6 pounds
MT ET Street Radial 275.40.17 weighs 28 pounds

The MT Radials were more consistent, but took 600-1000 more rpms at launch to keep from bogging.

BTW I do and did subscribe to a fast clutch release, rather than a big-slip. My approach yielded good 60' and 150-175 drag strip launches per stock clutch. When changed, the stock clutches (1) still had life left (2) showed very even wear and (3) gave no indication of impending failure.

Ranger

96-speed

iTrader: (19)

Ranger,

Thanks for the reply. I weighed my car at the track - not an estimate . It weighed 3450-3460 with 1/2 tank, and with ~1/8 tank left the car weighed in at 3400 with me. I weigh 250lbs. So, I think that is fairly close (~3150 by itself). I also have a laptop and a couple tools in the car when I go to the track. Probably 10-15lbs extra weight. Maybe I should look under the rear for a hidden trailor hitch?

I tried a BIG slip technique for the heck of it on one run and didn't have positive results . A quick engagement, like you have advised, seems to work best.

I was just curious about the wheel weights from a standpoint of rotational mass reduction. 60's being equal, did you notice any gain strictly from the [ever so slightly] lighter wheels?

I'm pretty impressed with the difference in your 01 and 02 cars. The mph is pretty spectacular, as well as the ET.

Ryan

96-speed

iTrader: (19)

Update for those interested:

Went out tonight and cut multiple 1.8s with the street tires. However, car would only go 12.2x. Here's the best pass:

1.889
12.231
114.80

Even with an 1.83 60' on one of the passes, the car wouldn't ET or MPH any better. DA was 996' (IIRC, the numbers were 28.86, 49º dew point, 68º ambient). Raceweight was 3420. The launch technique was a quick release off of 5k rpm. Track prep was excellent.

Ranger, you have a touch like no one else. The way the car runs, the only free mods to make it go faster are (1) better weather, (2) lighter wheels, or (3) harder driving than I care to dish out to my street car.

I'll wait for better weather and rinse, lather, and repeat .
Ryan