Bad Habit Bird

iTrader: (12)

well I will probably be ordering a 12 bolt tomorow. Im not sure when I will be able to make it out to the track again though.

I just thought I would point something else out though. Alan ran 11.69 @ 119 at HRP (and we know there timing equipment is right) When he made his runs at HRP it was 70 degree weather. Saturday night he trapped 121 in 45 degree weather and having about a 5~10 mph tailwind.

Is it so hard to believe that he picked up 2 mph running in those conditions compared to when he trapped 119? It makes sense to me that he would trap more with better weather and a tailwind.

So why is it so hard to believe I trapped 120. Our cars have identical mods but his car weighs less than mine does.

Also when I say raceweight I am talking about with me being in the car just thought I would clear that up.

[ March 11, 2002: Message edited by: Bad Habit Bird ]</p>

Colonel

I, for one, am not saying it can't be done.

Maybe you could clarify the conditions a bit to help others understand. What was the DA?

Let's assume for a minute that the timing equipment was working perfectly. It would be VERY interesting to see what kind of trap speed you would pull with drag radials (far better launch and no getting in and out of the throttle due to tire spin which is certainly not good for trap speed), better gearing, underdrive pulleys with the short belt mod, a FTRA, a C/F shaft, more weight reduction, a removed filter, and some REALLY good weather. What MPH might that bring? 125 MPH? <img src="gr_eek2.gif" border="0"> That would be as fast as the most powerful NA heads/cam LS1s out there with an internally stock NA engine! <img src="gr_eek2.gif" border="0">

BTW, do you powershift? That's often worth about a MPH depending on how quick your normal shifts are.

I'm sure folks would be curious to know an actual measured raceweight as well if you get a chance to weigh it.

Sally 5.0!

Alan ran 119 at HRP in worse conditions. He then ran 121 at TAD in better conditions. I think he was on ET Streets. I believe he even sixtied better. Sean ran his 120 on Nittos, I think.

If you want to see it in person, come on out. However, we did just put Alan's interior back in tonight. I'm sure he would be more that happy to remove it again. <img src="gr_stretch.gif" border="0">

RAGEman

iTrader: (4)

How do you find the DA, Stephen?

No powershifting. At least not on my part, and I'm pretty sure Sean doesn't either. Just quick hands/feet.

He was on drag radials.

By better gearing you mean taller as in 3.73 or 4.10, right? That would not necessarily increase trap speed, although it could.

He tried running an ASP underdrive crank pulley and for some strange reason, he was getting misses around 5K. As soon as he switched back to the stock pulley, it stopped.

My actual measured raceweight was 3200 lbs. I don't see why a stripped automatic-transmission LS1 running 119 MPH is accepted, but a stripped manual-transmission LS1 running 120/121 is impossible. Let's remember also that trap speed is an average speed over a short distance at the end of the track. Thus, if you happen to be in your powerband, you'll trap higher than you would if you were above or below it. I'm crossing the line right now on 26 x 11.5 x 16 ET Streets and 3.42 gears at around 5200 RPM's which is right in the meaty part of that powerband. Remember this, also, when you are talking about how many MPH you increased from the 1/8-mile traps to the 1/4-mile traps. I may be out of my powerband when I go through the 1/8-mile traps, but right in the middle of it when I pull through the 1/4-mile traps.

Until now, no one has been able to unlock the potential of the 6-speed bolt-on LS1. You guys just wait until I get my 12-bolt, clutch, suspension, Crane 1.8's, C/F driveshaft, and lose another 100 lbs. and run @ HRP on a cold day next winter. I can't wait to see the doubts flying then!

F8L Z71

I just wish I lived in Texas. CA. sucks for racing. But could be worse, I could live in SoCal. <img src="gr_images/icons/wink.gif" border="0">

RUQWIKR

iTrader: (11)

You guys (Bad Habit Bird) and Rageman are running great. Being from Dallas originally, I've raced at Temple, HRP, the Motorplex, etc.

With my auto, I'm picking up around 24-25 mph between the 1/8th & 1/4 mile in mine at a similar weight. So, with your manuals and a bit of a tailwind, I would have expected about 119-121 vs. my 118-119, just like you all ran.

That said, with some steep gears in a good rear...

These cars continue to amaze me. Good luck and take care.

F8L Z71

I pick up 25.5mph from 1/8th to 1/4 but that has more to do with all the timing I lose down low and by 90mph I gain it all back so I charging hard. Under a normal tune I doubt I will gain that much.

My 1/8th MPH: 89mph
My 1/4 MPH: 114.5-115

Colonel

Let's remember also that trap speed is an average speed over a short distance at the end of the track. Thus, if you happen to be in your powerband, you'll trap higher than you would if you were above or below it.

I disagree. It's not a measure of average acceleration throughout the last 66 ft, it's a measure of average velocity throughout the last 66 ft. For instance, if you entered the first light accelerating like mad at 115 MPH and reached the second light at 120 MPH (just speaking hypothetically here) and I entered the first lights at 119 MPH completely wound out and crossed the second lights still at 119 MPH, I would have the quicker trap speed. You were much better in your power range and I was tapped out. Doesn't matter. My average velocity was still higher through that 66 FT. <img src="gr_stretch.gif" border="0">

Your best trap speed will normally come with your RPMS somewhere a little higher than your HP peak. Your best ET will come at an RPM a little higher than that.

Point being, 3.42s aren't the greatest for trap speed.

Sounds like he got a bad pulley that caused a bunch of KR. I had one once too.

Colonel

BTW, I wouldn't call 5200 RPM the meat of your powerband. Your HP peak is where the most work is being done and thus is where the most potential for acceleration is. When you cross well below your HP peak you're missing out on the BEST PART of your power.

He had drag radials? That was a pretty slick track for sure. I was assuming he had stock tires based on his mod list...

"mods:
lid
ported maf
ported tb
Grot longtubes
3" y-pipe no muffler"

To figure DA I use a calculator like this one...

http://rshelq.home.sprynet.com/calc_da.htm

RAGEman

iTrader: (4)

I stand corrected, Stephen. I did say average speed, though, not acceleration. I just wasn't making the distinction between the two properly in my screwed-up little head. The way you explained that made perfect sense, very nice. That's why you're the Colonel and I'm still a Private. One day I will become Five-Star General, though, so watch your back. This discussion on trap speeds interests me very much. I want to be able to win highway races and long (1/2-mile) street races, yet still break the A4 bolt-on record. I thought building towards high 1/4-mile trap speeds would allow me to accomplish both of those goals. It appears as though I may be wrong, though. Can you perhaps shed a little more light on the subject?

125 MPH is the best MPH we've seen from a heads/cam LS1? If so, that is another shortcoming of my M6 brethren. That is another record I will be taking down, Lord willing.

Another thing. Does the fact that Temple Academy Dragway is IHRA-certified mean anything? I can also tell you what timing system they use, would that mean anything?

I will calculate the DA when I get home from work.

Also, when I ran 119.04 @ HRP, my clutch was slipping badly in 1st gear, whereas this past Saturday night, it wasn't slipping nearly as bad, if at all. Wouldn't that help my MPH (in addition to the much better air)?

RAGEman

iTrader: (4)

No can do on the DA calculation. I don't have all the info necessary to plug in.

Coach 02 A3 Z/28

iTrader: (10)

Alright boys, <img src="gr_images/icons/mad.gif" border="0">

I am going to Houston Raceway Park on Friday night test & tune, going to run the bracket race on saturday and maybe just maybe run instant green on sunday.

I ran at Temple Sat. & Sun going 5 rounds Sat. and 7 rounds Sun. Won the race. <img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

My car Sat. ran a 1.70 60ft, 12.24 et at 114.24 mph.

Sun. We ran 1/8 and all my times were faster Sun than Sat.

We will see what times I get at HRP this weekend. I think I will more than back up my times.

Just my 2 cents! <img src="gr_grin.gif" border="0">

Coach 02Z28 M6
Mods: Bolt ons
More to come April 1st <img src="graemlins/gr_devil.gif" border="0" alt="[devil]" />

Bad Habit Bird

iTrader: (12)

Sweet ok Coach will be the test subject. If he runs similar times as he did at TAD then that proves Alan and I were running what our timeslips showed. <img src="gr_grin.gif" border="0">

Colonel

"I want to be able to win highway races and long (1/2-mile) street races, yet still break the A4 bolt-on record. I thought building towards high 1/4-mile trap speeds would allow me to accomplish both of those goals. It appears as though I may be wrong, though. Can you perhaps shed a little more light on the subject?"

As with 1/8 or 1/4 mile racing, to win 1/2 mile races you will want to apply the most possible power to the ground over the course of the race. Not only the power curve but also the OVERALL gearing in each gear used must be considered. This means taking into consideration tranny gearing, rearend gearing, TQ converter characteristics (not in your case of course) and tire diameter (which can vary with speed and pressure.)

When I said that for max ET you generally will be crossing the line at an RPM a little above that which will yeild max trap speed, I didn't mean that trap speed will suffer greatly. Running out of usable RPM well before the finish line is not good for either ET nor trap speed but yes, normally you will find that if crossing the line at, say, 6500 RPM, yeilds max trap speed that crossing the line at 6800 RPM may yeild a quicker ET with a small sacrifice in trap speed. This is mearly one example and it will vary with different power curves among other variables.

In street racing the distance and MPH started from is most often unknown so building a car to best handle any street race is impossible. You might be geared perfectly in one race that starts at 40 MPH and goes for a 1/2 mile but not for a race that starts at 80 and goes for 3/4 mile.

One thought concerning street racing and gearing...it is more likely that you will find a gear close to your "sweet spot" with numerically higher gears when starting at an unknown MPH than with numerically lower gears.

If this provokes other thoughts or questions, do share them. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Bad Habit Bird

iTrader: (12)

Well the 12 bolt I ordered is coming with some 4.10's so hopefully they will put me in my "sweet spot" a little more quickly than the 3.42's <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />