*****Norwalk Ohio Test n Tune******

Any updates?

Me and Charlie (and his buddy with a BMW) were the only guys that went. There were a lot of people there, so each of us only got in two runs.

My better run was a 14.4. Im convinced that with a little more practice i could nail the launch and drop it into high 13s. With it being my first time at the strip and having ABSOLUTELY no idea what i was doing, im pretty happy with 14.4.

Great run! My first runs at Heath back in '06 were 14.9 and 14.6. But my launches on those were horrid, so I knew there was room for improvement. For the 13.9 run at Norwalk, I launched a 2.152 sec 60 ft, which is about the best I could hope for. If you're close to 2.1 secs, then it's all up to your engine and shift points at that point. If your launching 2.2-2.5, there's lots of room for improvement!

Also, I swapped to a 3.2 pulley for the 13.9 run, and being 50ºF ambient didn't hurt things.

Thanks! My 60' was 2.203. I didnt spin at all, and i know i could have punched the gas quite a bit harder and still kept traction. The tune that Scott and i have on the car is pretty basic right now... Stock shift points, no timing advance. Basically just tuned to 0 KR. I think the car will be pretty powerful once everything is tuned up right and i learn how to drive it a bit better.

Based on that I'd predict a 14.2 is possible with your current set-up. 2.2 secs is a respectable launch time on street tires!

Im definitely not unhappy with it! I dropped front pressure down to 25 psi, held at around 2200, and it didnt feel like it tried to break traction at all. The track surface is much, much different than the street for sure!

Yes, the track compound is so sticky, it's probably equivalent to having drag radials on the street. I think this is why drag radials are an added risk to the transmission - usually you're going to take it to the track for a double whammy.

As I recall, I had a difficult time figuring out the launch because it was so indistinct when the tires were spinning or hooking off the line. The pavement is really smooth. I'm hoping that won't be as much of a problem with drag radials and the torsen may help a little. I'm really curious to see what kinda 60ft I can pull off.

A .1 second improvement in 60' can be worth .2 seconds in E.T. That is the hardest thing to do with the front driver cars, get a good 60'. I would be afraid to use Drag Radials with our transmissions. I think you would grenade something. My best 60' with the GS has been 1.63. I foot brake it to about 2500 RPM, and just mat it at the first glimmer of the 3rd amber.

Tyler beat me! When we lined up I hit a: .70 R/T, 2.20 60', with an ET of 14.90 @ 93.64MPH!

I was running 30psi in the front and 40psi in the back. probably shouldve lowered it a lil more, huh?


My intake soaked in so much heat! It was ~58 degrees ambient and my intake was reading 100degrees from sitting in line waiting to roll!

Youch!


Anyways, next time I will drop the tire pressure to 25ish and keep on practicing that launch at every stop light in town.. jk jk.. not really tho

I did about the same my first time out. I noticed some of the other guys doing things I wasn't like: checking & adjusting tire pressures, pushing their cars through the staging lanes, and setting bags of ice on the blowers. They were talking about shifting at certain RPM, launch technique, etc. Next time I was on it!

You guys had identical 60' times, so it was really up to the cars.

Great runs guys! There is nothing wrong with mid 14s. (high 14s?)

I try to scan multiple parameters anytime I run. I'll start the scanning right before stage and sometimes I forget to stop scanning until I'm back in the pits... but at least I have the critical info.

Charlie launched in 2 and said he held it until he was scared and shifted. I just launched in drive. Is launching in 2 the way to go or does it not really matter?

It can matter, but only if the engine has the breathing mods and the gear is held long enough. The only way to know for sure is to graph your power (HP) curve on the dyno. Next you'll need to know at what RPM you land when shifting from 2nd to 3rd. For example, a stock 3800 SC shifts from 2-3 at 5400 RPM. In 3rd, RPM lands about ~3500 RPM, coincidentally at about peak torque.

Note that peak 240 HP occurs at 5200, not 5400 RPM, but the shift occurs higher because even when HP starts to drop above 5200, there's still more power at 5400 than at 3500 RPM after shifting to 3rd. There's a point at higher RPM where the HP drops off enough so there will be more power delivered after the shift. For example, shift at 5800 stock and at 3rd you land at 3800 RPM making higher HP. This means you wasted some HP before the shift - should have shifted earlier.

The point is, you want to rev as high as possible so that HP in 2nd is just slightly higher than when you land in 3rd, and you can only know this running on a dyno with all your mods installed, graphing the curve.

Looking at my curve, HP is pretty steady until 3950 where it ramps up (rockers) all the way to peak HP at 5350 RPM. The HP then drops through 6000, where it about equals power made at 3950. But remember shifting at 6k causes the 3rd shift RPM to be higher, around 4000. As a result 3rd gear HP is also higher, so shifting at 6k won't help me. But shifting at 5900 puts me at ~3900 RPM in 3rd. This is just about perfect for my set-up.

Sorry if that doesn't compute. If needed I can supply a graph to illustrate

Some cammed engines and those with higher flowing heads can move the torque curve high enough in RPM to keep HP high to 6k, even 6.5k RPM. This is what really makes cars fast on the track, not smaller SC pulleys. By adding boost and suppressing with KR, all that's really accomplished is moving torque lower in RPM, requiring lower shift points, and effectively making the car slower in a race (but great fun for driving on the street!)

Ok, that does make a lot of sense. I never took into consideration the RPM that the motor went to after the shift. Stock shift points need to be raised a bit i think. When it shifted at 5400, i could tell that motor wanted to keep pulling, and after the shift it lagged just a bit.

It may help a small amount, or it may be a wash. The thing is, you really can't feel HP by feel. The pull from torque is easy to feel, but that's not the same as power; it doesn't actually mean you're moving faster than the other guy. The time of your shifts are just as important. You're thinking is right - pulling longer is better, but only if you upshift into the gear producing slightly less HP. The only way to know is math and graphs, unfortunately. Or you can experiment with different shift points and time your runs!

Shifting into 1 will increase the fluid pressure, which might be desirable on launch. After that, though, you might as well be in D or 4/OD/squareD as the shift points will be the same. The fluid pressure increase only happens if you pull the shifter all the way to 1.

Just don't shift to N!

Sounds like its time to get the old girl on a dyno!

If you want to, but we're talking about marginal improvements to your times. When I was looking for that extra .05 sec to push into the 13s, holding the shift was part of getting there. I didn't have the car on the dyno yet at that time, I just guessed it would work. Later when I had a HP graph I could see why it worked!

Sounds like Psycho is itchin to finish his tune.....let me know when man.

Bros, 4/25; first test n tune of the year at Norwalk.

Let's do this.

http://summitmotorsportspark.com/index.php/component/jevents/icalrepeat.detail/2014/04/25/190/-/-?Itemid=1

Lets go! I'm absolutely down.

Sir Psycho Sexy wrote:

Lets go! I'm absolutely down.

Can't wait, homie! Hope Scott can make it too! Maybe even AA?

Rivs killin err'thang on the strip! Wonder if Scott's Riv will be done by then...

Maybe. Depends on the schedule. Looks like fun.