Back to the Track (with side pipes)

[gedmeyer]

Well, I finally made it back to the drag strip tonight. This is the first time since I ran the vette at the strip since I put the hooker side pipes on (and only my second time ever)! The weather was near perfect, mid-low 70's and dry!

My best run:
R/T: .415
60: 2.268
330: 6.097
1/8: 9.196
MPH: 79.86
1000: 11.883
1/4: 14.109
MPH: 100.8

Obviously my R/T is terrible. I have a terrible tendency to just hammer the gas and dump the clutch when I see green light. The tires don't have any chance of grabbing. In anycase, I think the car definitely has a litte more in her, if in the hands of a better driver. All in all, I'm pleased though. I'm sure she could break the 14.0 barrier. My 2.8x rear gears don't kick in until I'm winding up 3rd gear (I passed a lot of cars in the last half of the track). I did manage to bark 3rd gear at WOT.

As for the sidepipes...I LOVE THEM! I got 0.6 seconds from them and they sound beautiful going down the track.

I can't wait to go back. I WANT MORE HP!

-gedmeyer

oh, I did beat up on a mustang pretty good too!

 

[bill81vette]

nice kill,tim ET looks pretty good as well!!!!


you gonna get it dyno'ed or no??

bill

I'm thinking late next month when the leaves start to change we'll go for a cruise in the mtns???

 

[gedmeyer]

I don't know about the dyno. I don't know if I want to spend the $150.

I was hoping to get my E/T into the 13's. I know she's got it, it's just a matter of a good lauch and traction.

Yeah, let me know when you want to go cruisin!

-tim

 

[74bigblock]

Tim,


Best way to launch is to practice. Pop the clutch while holding the gas at different RPM's and see where you get the best performance. Once you narrow in on that sweet spot, you can do it all day!

As for the R/T... pop the clutch after you see the last orange light come on. It takes a 10th or 2 for your car to move forward enough to trigger the timing light... (there is about a foot between the last stage light and the timing beam) by jumpstarting like this... you can see an R/T closer to 0.0. The down side is if you pop it too early you red light, but who cares if you are just running to see what your E/T is!

Glad to hear you are enjoying those side pipes!

Dave

 

[gedmeyer]

I lowered the air pressures in my tires for the last run. The problems was that I didn't have enough rpms in that launch and the car studdered for a moment. With the lower pressure, I think they hooked up OK but I just needed RPM. A lot of people were at the track and I didn't feel like waiting around for another run. Maybe I'll go back in a couple of weeks.

I went to the track with a buddy who has a 2003 SS silverado with a supercharger. He runs mid-high 13's. Kinda embarassing getting beatup by a pickup. So I need to find a few ponies somewhere so I can keep up!

-gedmeyer

 

[warren s]

It takes practice, after a bunch of runs my 99 ran a 13.12, my best try was using the bog-n-go technique. Slicks would be nice, but then the clutch smokes instead of the tires.

 

[gedmeyer]

It takes practice, after a bunch of runs my 99 ran a 13.12, my best try was using the bog-n-go technique. Slicks would be nice, but then the clutch smokes instead of the tires.

Yeah, I don't want to run slicks b/c then something else becomes the weakest link. I'd rather burn rubber than stap something.

I wasn't doing burnouts to warm up the tires either.

After being at the strip last night, I WANT MORE! I think I might go back in a few weeks if I get a nice night.

-Tim

 

[L48]

(there is about a foot between the last stage light and the timing beam)

I think the foot you are referring to is "rollout". Your time starts when the tire clears the staging beam. People who deep stage give up that foot of rollout and put the tire where just a slight movement will start the timer. The amount of rollout you have is dependent on the diameter of your tire and how far you roll forward into the staging beam when you stage. Some people like to creep up to the staging light so that they get the maximum amount of rollout. Others like to roll as far as they can almost past the point where the staging light registers them (this is deep staging).

There are two beams, one for pre-stage and one for stage. If there is another one there I have not seen it.

 

[Glensgages]

As for the R/T... pop the clutch after you see the last orange light come on. It takes a 10th or 2 for your car to move forward enough to trigger the timing light... (there is about a foot between the last stage light and the timing beam) by jumpstarting like this... you can see an R/T closer to 0.0.

I'm guessing it'll take longer than even .2-seconds for this car to start the ET-clocks, and stop the RT-clocks, if he leaves 'both-bulbs-lit' :
my '79 Z28 runs high-12's, with a 60' time of 1.85, has approx 400 (crank-shaft ) HP, an 8"/4500-RPM converter, 4.11 gears, and slicks, and I have-to deep-stage, and launch at 3500-4000 (depending-upon which track I'm at ) to get consistent .01-.03 RT's.....

I'm sure she could break the 14.0 barrier. My 2.8x rear gears don't kick in until I'm winding up 3rd gear.

With even a 'tall'-gear like 3.36's, I think you'd be WELL-into the 13's, providing you can hook-up:
when the Z28 was much-younger, it ran 14.40's @ 97 MPH with 3.42s, and 14-teens @ 97 MPH with nothing-else but 4.11s.....

My '82 Corvette ran 15.70 @ 86 bone-stock with 2.87's, and as-quick-as 15-flat (.004 ) @ 91 after a swap to 3.73s:
some of my racing-buddies use a tenth per .25 of gear ratio, while other say that each .1 of gear-ratio equals .06-seconds of ET.....

Either-way, you are close:
a decent set-up 'street-car', with proper rear gears, should have it's ET, multiplied by it's MPH, come-out to approx 1360-1380, so 1380 divided-by your MPH (100.8) would be (approx ) 13.69 ET

 

[gedmeyer]

Thanks Glensgages. I think I would like to put in either 3.54 or 3.36 gears in ( I do a lot of highway driving). Unfortunately, I've never been inside a diff before, so I think I should save this sort for the shop. In any event, I'm going to hold off from spending the $$. I've determined that my next projects on the car will involve creature comforts (a/c, floor insulation, replacing front speakers) and then rear suspension work (springs, shocks, bushings) to tighten everything up back there.

Is it possible to have my transmission rebuilt with taller gears in first/second?

Where else would I find (lose) some E/T? I'm running a Comp cams 270H Magnum cam (.470" lift). I'm running stock heads, intake, carb (w/ richer secondary rods). Or am I kinda stuck my current power range w/out trashing my top end? I don't plan on dragging my car regularly, but it is nice to know that I have a fast car!

 

[Glensgages]

I think I would like to put in either 3.54 or 3.36 gears in ( I do a lot of highway driving). Unfortunately, I've never been inside a diff before, so I think I should save this sort for the shop. In any event, I'm going to hold off from spending the $$. I've determined that my next projects on the car will involve creature comforts (a/c, floor insulation, replacing front speakers) and then rear suspension work (springs, shocks, bushings) to tighten everything up back there.

Swapping the gears from 2.87s to ANYTHING in the mid 3-series will be the biggest improvement you will see, at this point in time:
try POWER-TRAIN, 631/589-7020, on Long Island, where I got my 3.73s for $125 less S&H 2 years ago.....

Is it possible to have my transmission rebuilt with taller gears in first/second?

For maximum, off-the-line accelration, you'd want DEEPER gears, not 'taller' gears, and I can't help you on that one.....

Where else would I find (lose) some E/T? I'm running a Comp cams 270H Magnum cam (.470" lift). I'm running stock heads, intake, carb (w/ richer secondary rods). Or am I kinda stuck my current power range w/out trashing my top end? I don't plan on dragging my car regularly, but it is nice to know that I have a fast car!

Without tearing the top off, I think you're pretty-much maxed-out (but 14-flat at 100 ain't TOO-shabby, and probably surprises a few C4s!!!!! ).

Some very basic tricks:
* run your tires at max PSI, to decrease rolling-resistence.
* stage as 'shallow' as possible..... more roll-out equals lower ETs.
* remove the front sway bar..... let the front-end 'do-it's-thing' on the launch.
* run a full tank of gas..... the weight over the drive-tires helps traction:
'generally', for every .01 quicker in the 60', you'll pick-up ANOTHER .01 down-track due to momentum.
* try various shift-points for the different gear-changes..... you MIGHT find you go quicker short-shifting certain gears.
* your quickest runs may come when the trans and rear-end are warmed-up (fluids thinned-out ), and with cooler engine water temps (more power ).

Hope this helps!

 

[gedmeyer]

* run your tires at max PSI, to decrease rolling-resistence.

Which yields better times, less rolling resistence (higher pressure) or more traction out of the box (lower pressure)? Most people have suggested less tire pressure or slicks of some sort.

 

[Glensgages]

Which yields better times, less rolling resistence (higher pressure) or more traction out of the box (lower pressure)? Most people have suggested less tire pressure or slicks of some sort.

This is almost like the double-edged sword.....

you want to run as-much rear PSI that will allow the car to hook-up:
this allows minimal rolling-resistence the remainder of the run, and the lowest possible ET for that run
(this is why I suggest running a full fuel-tank, too, to maximize the weight over well-inflated drive tires ).

I believe that radials tires don't LIKE to be under-inflated, and that this causes them to buckle-up on the inside of the tread, leaving only the outer and inner edges in-contact with the track:
too-much rear PSI and they 'balloon-up', riding only on the center of the tread, minimizing traction.

The only 'sure-fire' method to determine this is repeated test-and-tune sessions at the strip, changing ONLY one thing at a time:
if you change the launch RPM, and the rear PSI, and you see a significant difference, how do you know WHICH change caused the improvement?

Work on your 60' times, and consistency in staging, launching, and shifting:
as I explained before, whatever ET improvement you see in 60' will almost surely be matched the rest of the run (i.e. if you knock-off .03 in 60', chances-are you'll go .06 quicker in the 1/4-mile ).

Consistency is also most-important:
if you change your shift-points AND your launch RPM, how will you know WHICH change worked, and which didn't?

 

[gedmeyer]

Would you recommond the 3.73's or something smaller? I'm calculating that I should turn 75mph just under 3500 rpm with these gears. I am on the highway a good amount (although, the vette sees less than 3000 miles a year).

So you recommend POWER-TRAIN for parts? I don't want to install "cheap" parts. I have someone lined up (GM service guy) who would install the gears, provided I remove the diff and bring it to them.

-Tim

 

[Glensgages]

Would you recommond the 3.73's or something smaller? I'm calculating that I should turn 75mph just under 3500 rpm with these gears. I am on the highway a good amount (although, the vette sees less than 3000 miles a year).

I'm not the guy to 'reccommend' gear-ratios for you:
I like a lotta gear in my cars (woulda put 4.11s in my '82, had they been available..... ), and I do very little highway driving.....

" ASSUMING " you run a 27" tall tire, and the high-gear ratio of your 4-speed is 1:1, I calculate these RPM-figures for 75 MPH:
2.87 gears: 2650+ RPM
3.08 gears: 2850+ RPM
3.36 gears: 3100+ RPM
3.55 gears: 3280+ RPM
3.73 gears: 3450+ RPM

So you recommend POWER-TRAIN for parts? I don't want to install "cheap" parts. I have someone lined up (GM service guy) who would install the gears, provided I remove the diff and bring it to them.

-Tim

The fella who installed my gears had over 15 years as a GM service-man, and he saw nothing wrong with the ring and pinion, which are PRECISION GEAR-brand:
he also has had several hot-rods and drag-cars, and thought the DANA-44 rear-end was the WEAKEST he'd ever seen before, and advised (TOLD ) me to not run any sticky-type tire on my '82, even with the wimpy Cross-Fire.....

He charged me 'only' $350 for labor and miscellaneous parts (gear-lube, shims, etc. )

 

[dfw81shark]

I bought my 3.54 ring and pinion from Precision Gear. I'm happy so far. We're coming up on 2000 miles and a year or so now. My rebuilder had a mixup on his parts availability of the Dana-44 (Corvette) 3.54, so he told me to bring him the gear. I called up and Precision was very friendly and happy to send me the gear. Turns out it was the same P/N my rebuilder said wouldn't work (according to his book because there are a ton of DIFFERENT Dana 44s). I told the builder to try it anyway. He had trouble getting it back into the carrier iirc. Precision patiently talked to me on the phone over the course of a week and I eventually told the rebuilder how to get it back in myself from instruction from the Precision folks. The 3.54 was physically bigger than the 2.87. I recommend them based on my experience because they went way above their responsibility to me.