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 my 1st strip data on German amateur track
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dutch71 formula
Tribal Scout

14 Posts

Posted - 29 Apr 2013 :  4:52:53 PM  Show Profile  Reply with Quote
Hello To All,

Long time no "read/write".... just been to busy...

Last year i had some runs on a amateur 1/4 mile event in Germany.
Unfortunattely very rare around here. These events take place 2 to 4 times a year. I want to run the Firebird again this year and want to improve the times.

I want to share the numbers with you and hope you can give me some tips to tweak some more time of my ET's. This was my first trackday ever and i had a lot of fun, even made it to Television in Germany. see run 7 in the tv report (allthough mixed together for television might give you some extra info):

http://www.wdr.de/mediathek/html/regional/2012/10/13/sportlich-unterwegs_filmautobahn.xml Here the numbers from the 7 runs that day, Run 7 is the one got filmed with the reporter at the passenger seat.

I try to give as much info as possible, hoping it helps to get an idea of the car and my skills (remember it was my first time;-)

Reaction times vary between 0.052 and 0.7 sec. Times mentioned below are without reaction times!
run 1:
60 feet: 2,174 sec. 1/8 mile 8,881 sec 1/4 mile 13,465 sec
1/8 mile speed 82.85 mph
1/4 mile speed 102.24 mph
run 2:
60 feet: 3,002 sec. 1/8 mile 9,612 sec 1/4 mile 14,160 sec
1/8 mile speed 83.77 mph
1/4 mile speed 104.13 mph
run 3:
60 feet: 2,204 sec. 1/8 mile 8,754 sec 1/4 mile 13,301 sec
1/8 mile speed 85.03 mph
1/4 mile speed 102.94 mph
run 4:
60 feet: 2,390 sec. 1/8 mile 8,967 sec 1/4 mile 13,480 sec
1/8 mile speed 84.40 mph
1/4 mile speed 104.86 mph
run 5:
60 feet: 2,372 sec. 1/8 mile 8,954 sec 1/4 mile 13,458 sec
1/8 mile speed 83.93 mph
1/4 mile speed 105.10 mph
run 6:
60 feet: 2,254 sec. 1/8 mile 8,842 sec 1/4 mile 13,408 sec
1/8 mile speed 83.77 mph
1/4 mile speed 103.65 mph
run 7:
60 feet: 2,252 sec. 1/8 mile 9,161 sec 1/4 mile 13,858 sec
1/8 mile speed 80.04 mph
1/4 mile speed 101.09 mph

The setup of the car right now:
One of Jim Leharts 406 Long Rod
-.30 bored 400 ci engine with 6X/4 Light ported heads
-6.8 eagle Forged Pistonrods
-Speed Pro 455 pistons
-factory windage tray
-milowdon 7quarts oil pan
-Melling high volume oil pomp / .dubbel timing chain
-competiton cam flat tapt Xstreem Energy 274 camshaft
-competition cam 1.5 Magnum roller tip rockers and HT-951 Hydr. Lifters
-2.11 and 1.66 valves
-Competition cam valve springs
-Ported Torker II manifold
-9.5 compression
-Wilson 1" spacer on top of the torker II
-MSD 6A ign. and MSD Billet distributor with no vac. advance.

new Koni non adjustable shocks front and rear
Stock rearsprings and Hotchkiss lowered frontsprings
2ndGen Pro subframeconnectors and additional swaybar bottom and adjustable at the top of the enginecompartment

-Carb. 750 Holley AED mech. 2nd with open airfilter.
-2.5 " dual exhaust with X-Pipe and absorbtion type Mufflers on sort of Hooker like headers
-Tranny TH400
-3.43 gearing with Yukon Dura Grip Positraction
Tires at the rear M/T ET Street Radial 275/60/15
At Start almost zero wheel spin with the M/T's after short burnouts, starting at 1st gear. Manual Shifting the Th400 at about 5900 rpm manually from first to second to Drive.
Shifting at higher RPM goes not very good, you can hear it in the vid i hope. When i slap the next gear i have to release the pedal
otherwise it won't shift. Vacuum problem on the TH 400 ???

GPS tested actuall topspeed of the car is about 135MPH at 6000RPM,
so i ran out of track at the end i guess when you look at the numbers.....

I hope you have some tips for me.

kind regards Frans


5448 Posts

Posted - 29 Apr 2013 :  9:01:48 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Shoot from the hip, and i'm not too good at this, maybe move to 3.73 gears and up to the XE284 camshaft?
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Blued and Painted

3505 Posts

Posted - 29 Apr 2013 :  11:43:55 PM  Show Profile  Reply with Quote
The mile per hour is pretty good showing the engine is making good power but the 60 ft time should be less than two seconds. I would say the torque converter is bad or not matched to the combo. Looks like the converter should flash to 2800rpm's
You are also loosing A LOT of time letting off to shift.
That is an EASY fix with a programmable shift kit or a manual shift conversion kit for the valve body in the transmission.

Looks like you smoked that Challenger in the video. Keep up the good work.

Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 29 Apr 2013 11:54:50 PM
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Crazy Horse

852 Posts

Posted - 30 Apr 2013 :  12:16:36 AM  Show Profile  Reply with Quote
Good numbers for the first time at the track. The car has some good potential. Definitely square away the tranny issues and I bet you could be getting damn close to 12s.

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Crazy Horse

823 Posts

Posted - 30 Apr 2013 :  9:35:34 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
Yes your 60 ft times need a lot of help. I agree with B&P the right torque converter will get you out of the hole quickly as long as your rear suspension is right and tires hook off the line. A good performance TC like 2400-2800 stall. Personally, I would never run any less than 3.55's on a Pontiac with an auto trans. 3.73 with 28" diameter tires are a pretty good all around street/strip. I also agree that you should be able to get into the high 12's

Pure Pontiac: learn it, live it, love it!
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Sitting Bull

80 Posts

Posted - 01 May 2013 :  6:35:36 PM  Show Profile  Reply with Quote
I allso agree 2800 stall torque converter , try shifting at 5400 rpm. 85 mph in the eighth is low 12's with a good 60 foot time.
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dutch71 formula
Tribal Scout

14 Posts

Posted - 08 May 2013 :  12:28:38 PM  Show Profile  Reply with Quote
Hello GUys,

thanks for your input here. Problem is i have problems with the tecnical English and dont understand everything, for example the
explanation for the Shiftkits, what do the transgo shiftkits actually do. After reading the manual i think i can install them myselves.
I ask the guy who rebuild the TH400 what parts (Torque converter and shift kit) he used. The invoice says Transgo Shift kit Street (maybe the SK-400?? Also mentioned on the invoice "Intermediate HD sprag 34 element (2nd gear)" dont know what it is??

I hope he is willing to provide me the information, i will post them later. Also can look if and what TC i will have to go with after i got the info.

Today i checked the TDC, the ignition and vacuum to ad the info here.
TDC is nicely at the zero degrees marking (just to check if the balancer is OK (i hope this is the way to do??).

Ignition is at 12 degrees initial at 700 rpm idle.
when reving up it wil go to about 33 degrees max. MSD distributor with no vacuum advance, only mechanical.

Vacuum taken on the T-2 is about 8 hg, when revving up it goes to
spmething like 17 hg (i always thought the vacuum went down when revving up???)

In the next few weeks i will build me a set of caltracs like traction bars, because i think the combo is killing my rear leaf springs. The reason for this is that i was assuming a good set of traction bars will also improve 1/4 mile time??
For your info, a set of caltracs wil cost me about 600 USD here !!

For the rear ratio i cannot put money in there right now, so i have to do with the 3.43 : 1.

As an alternative try out: The stripdata are run with M/T ET street radials 275/60/15 (27.99 Inch diameter)
I also have a set of M/T ET street radials 235/60/15 (26.1 inch diameter)
switching to the 26.1 Inch M/T would also give me a ratio compared to
3.73:1 with the 27.99 inch M/T's when i done correct calculating??
Offcourse are the 235 widt tires not as wide, but i will see what happens. Any thoughts there??

Now offcourse i will try to get under the 13. seconds ;-)

Other info that might be important:
Here at my place i can get gas in germany a few kilomters from here.
I can shoose from 98 octane up to Shell V-Power with 100 octane or even Aral Ultimate with 102 Octane. These are regular kinds of gas around here and no special race fuels. Lowest Octane fuel around here is 95.

Thanks for your help, i learn something new every day around here.
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dutch71 formula
Tribal Scout

14 Posts

Posted - 08 May 2013 :  4:36:23 PM  Show Profile  Reply with Quote
just got info of the shop that rebuild my th400:

-Transgo shiftkit is indeed the standard SK-400.
-TC is a regular low stall convertor 1300 - 1500 rpm
-governor was changed for high performance (later shifting than stock)
-vacuum modulator is for low vacuum engines (small type red stripe)

hope this helps getting a better picture of my combo
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Crazy Horse

823 Posts

Posted - 08 May 2013 :  8:57:54 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
Frans, I must commend you for owning a sweet Pontiac in a place that I'm sure they are hard to come by. You guys are lucky to have easy access to high octane fuel, there's only 3 gas stations on the north side of my town that I know of with high octane.

The timing sounds good. As far as tires, I'd stay with 275/60's especially if you have poor traction out of the hole. You're right about the effective gear ratio difference but the wider the better.

It sounds like you have a well built trans with the right upgrades like the improved sprag upgrade and a shift kit which "tightens up" the trans with higher line pressure and snappy shifting. The TC is barely above stock.

For now I would just work on the rear suspension, you can always order a new TC and slap in to try it out before going to the track if you continue to have trouble. Because the way I see it is that the better suspension is something that is necessary and you can live with even as you get faster. A torque converter ideally could be changed out after putting in a hotter cam or steeper gears.

I agree about your plans for the rear suspension. All of us muscle car owners realize after a trip to the track that the 40 year old suspension leaves a lot to be desired once you start trying to put a decent amount of power to the ground.

Pure Pontiac: learn it, live it, love it!
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