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Organized Drag Racing and AutocrossDrag racing and autocross discussions and questions. Techniques, tips, suggestions, and "what will I run?" questions.
After 2 years of owning my 92 B4C I finally got the chance to take it to the drag strip. Last night was the opening Wednesday test and tune at our local track, Muncie Dragway. I met up with some co-workers and friends to go knock the dust off. We had a pretty unique group. My 92 L98 B4C of course, a 99 Trans AM with a junkyard cam only 5.3 LS and Th400 trans, an 07 Colorado with a 5.3 and 88mm turbo with a TH400, 15 Z06 with a cam and full bolt-ons and a 00 SS Camaro with a 5.3 80mm turbo and Th400.
I haven't done any modifications since purchasing the car. Just some maintenance ect. No timing adjustments or anything. The car has a pair of SLP runners and edelbrock headers for sure. The previous owner claims it has a Comp-u-cam in it, but Im not sure. I wanted a true baseline run out of my B4C. So I drove it over and pulled right in the lanes. First pass was 14.61@94.8mph with a 2.01 60ft. The pass went really well other than late shifting. It hooked really well. Shifted around 4700rpm out of 1st but wrung out to about 5300rpm out of 2nd. I let the car cool off for a bit and helped my friend make some runs in his 2000 Camaro. It was a pretty rough first night at the track. One guy lost his brakes and ran off the end of the track rolling 3 times. A second guy ran off the end but I never heard what happened to him. Then a 3rd car turned the engine inside out and spit a bunch of rods on the track. Then drove over his own oil and brushed the wall. Once all that mess was over I got to make one more pass. I left a little harder but still had the same 2.01 60ft. It shifted good on the 1-2 shift around 4700-5000rpm. But on the 2-3 shift it really hung it out to about 6000rpm. The car nosed over and lost some time. I had to lift slightly to make it shift and ran a 14.47@95.8mph.
So Im going to pull the governor out of the transmission and see if its sticking or broken. Id really like to get a low 14 second pass out of the car before I start making any changes to it.
I figure you can get into high 13s with the mods you have.
Im hopeing I can get it down there before the first round of mods. I have a 2600 stall, aluminum driveshaft and drag radials to go on it. Then an Accel intake base.
The 700R4 is holding you back. It's a great transmission for the street but a poor transmission for racing. The 3.06 first gear can get you off the line quickly however the spread between 1 and 2 is too great. After the 1-2 shift, the engine rpms will drop down below the curve and there's a delay before the rpm gets back up into usable power. You might get a faster pass by manually shifting the transmission and holding first gear to a higher rpm before shifting into second.
When I started racing my car, it already had a nice 383 swapped into it but had crappy smog heads and a 700R4. First pass down the track was a 15.0. Tweaked it all year and got it down to 14.0. After the first season I swapped out the smog heads for some old school heavily ported camel heads with big valves and swapped out the 700R4 to a TH350 with a 3800 stall converter. First pass in the second year and I ran a 12.0. Everyone was asking where I hid the NOS bottle.
The old school 383 with stock cast pistons and stock 400 rods and bolts didn't like 7000 rpm shifts and spit out a lot of parts on the last day of the second season but I did manage to get an 11.8 that season. Engine damage was so bad that I pulled the intake and heads off and threw the rest into the scrap metal dumpster at work.
The 700R4 is holding you back. It's a great transmission for the street but a poor transmission for racing. The 3.06 first gear can get you off the line quickly however the spread between 1 and 2 is too great. After the 1-2 shift, the engine rpms will drop down below the curve and there's a delay before the rpm gets back up into usable power. You might get a faster pass by manually shifting the transmission and holding first gear to a higher rpm before shifting into second.
When I started racing my car, it already had a nice 383 swapped into it but had crappy smog heads and a 700R4. First pass down the track was a 15.0. Tweaked it all year and got it down to 14.0. After the first season I swapped out the smog heads for some old school heavily ported camel heads with big valves and swapped out the 700R4 to a TH350 with a 3800 stall converter. First pass in the second year and I ran a 12.0. Everyone was asking where I hid the NOS bottle.
The old school 383 with stock cast pistons and stock 400 rods and bolts didn't like 7000 rpm shifts and spit out a lot of parts on the last day of the second season but I did manage to get an 11.8 that season. Engine damage was so bad that I pulled the intake and heads off and threw the rest into the scrap metal dumpster at work.
You are absolutely right. It would be much faster with a different transmission and a loose converter. Transmissions are how I make my living. Id love to throw a TH350 or 400 in this thing. But its just a fun cruiser. I was to retain overdrive and keep a stock appearance. Id like to get it into the low 13s/ high 12s stock appearing.
You are absolutely right. It would be much faster with a different transmission and a loose converter. Transmissions are how I make my living. Id love to throw a TH350 or 400 in this thing. But its just a fun cruiser. I was to retain overdrive and keep a stock appearance. Id like to get it into the low 13s/ high 12s stock appearing.
While the 700R4 is much maligned, it can still be an effective drag racing transmission. If you're talking mid 12's it's easily done. Otherwise I wouldn't have done it!
First dip into the 12's, and 3600 lbs at that, took a 3.70 rear gear, MT ET Street DOT slicks, an off the shelf TCI 10" converter and a Vortec headed 350.
The TH700 had a TransGo shift kit, upgraded boost valves and a Corvette servo. Frictions and steels were nothing special.
Best I could was foot brake to about 2200 RPM. Flash stall was a little higher maybe seeing 3500. Hard to say. I always foot brake launched.
I'll agree on the 1-2 shift RPM offset. It's an ET killer. So is the 2-3 shift timing if you don't get a little deeper into the transmission. That said, once we upgraded to a Yank 3600, the shift recovery improved immensely. Instead of a drop to 3800 from a 6500 RPM 1-2 shift, the converter kept the revs at no less than 5k. That along with the better 60' from the increased stall knocked 2/10ths off the 60 and nearly half a second at the top. Went low 12's.
Both converters were lockup versions too. Very drivable on the street as well.
I've since had a "Level 4" (as per GearStar's spec) built with a pile of high zoot parts. I've a build sheet somewhere if you're interested (seeing as your a transmission guy). What it did was tighten up all of the shifts. The 2-3 was like lightening. Track results are still pending.
Having said all of that, any self respecting Super Stock drag racer will avoid the 700. As you said, a TH350 is a better trans in that regard if for nothing else other than it's lighter and the rotating mass is considerably less. Ergo, faster to rev and eats less HP to run.
3rd gens and C4 Vettes got the wrong induction system (TPI) and automatic transmission (700 R4). This is the perfect setup for a truck, van, SUV, heavy body on frame car.
3rd gens and C4 Vettes would have been better off with a high performance version of TBI and a 200 4R transmission.
I posted the above a few days ago in another thread.
Sonnax makes a 6 pinion planetary gearset set that changes the ratios for 1st and 2nd gear to make the 700 R4/4l60 a close ratio transmission.
Damage to the band, input/output shafts, sprag, etc. can be reduced by properly cushioning the large ratio change on the 1-2 shift:
Never use a 1-2 servo that eliminates the cushion spring
Never reduce the 1-2 accumulator piston stroke
Never leave out the 1-2 checkball
Never over-drill the 1-2 feed hole
Reduce ratio change by converting 1st Gear from 3.06 to 2.84 with Sonnax input carrier kit 77284-K, a great way to gain a better performing, more durable transmission. The one-of-a-kind Sonnax gear set improves overall launch in powerful applications, plus reduces stress on band and clutches on the shifts. The chart below shows how changing to the 2.84 gear set offers benefits go far beyond a 1st Gear ratio change. 1. There is an obvious change to the 1st Gear ratio: 3.06 to 2.84. This reduces the overall ratio ‘spread’ from 1st Gear to 4th Gear, making a close-ratio transmission compared to the OE ratios being a wide-ratio spread. This change mostly affects the Starting Line Ratio (SLR) which is calculated by combining the transmission ratio with rear axle final drive ratio and then tire radius. The reduced torque multiplication (from 3.06 to 2.84) also reduces the torque loads on some transmission components. 2. There is a less-obvious, but still important, change in the ratio drop BETWEEN gears. With less ratio drop between gears, there is less work required of the clutches and band to make the ratio change happen. A smaller ratio drop also reduces the shock loads on related hard parts. At both the 1-2 shift and the 2-3 shifts, the Sonnax input carrier delivers a reduced ratio drop. From 3rd Gear on, the OE and Sonnax gear ratios are the same.
This truck has the Sonnax close ratio 6 pinion planetary gearset installed. Toward the end of the video they show a 0 to 100 street pull before and after the gearset change. Notice the sound difference and RPM drop as it shifts through the gears.
I'm really looking forward to getting it dialed in. Trans tweeks and a converter are definitely coming.
I'm very familiar with the sonnax 2.84 gearset. I've probably sold over 100 of them in my career. I don't think it will do much in a low power application such as mine. It really hurts performance in low power and heavy applications. Once you install a higher stall converter the sins of the 3.06 first gear are forgiven some with less RPM drop on the 1-2 shift.
I'll update the post as I get out to the track more.
I'm really looking forward to getting it dialed in. Trans tweeks and a converter are definitely coming.
I'm very familiar with the sonnax 2.84 gearset. I've probably sold over 100 of them in my career. I don't think it will do much in a low power application such as mine. It really hurts performance in low power and heavy applications. Once you install a higher stall converter the sins of the 3.06 first gear are forgiven some with less RPM drop on the 1-2 shift.
I'll update the post as I get out to the track more.
I upgraded to the 5-pinion planetaries for the last transmission (same ratio). Funny thing though, despite the greater number of pinion gears to spread the load, there's evidence to support that these "new" planetaries are actually weaker than the 4 pinion that they replaced.
Vorteciroc (a member here) is a former GM Powertrain engineer and he brought that up in a thread I had started. Mine are genuine GM which is far and away better than the offshore aftermarket and at my power levels there doesn't seem to be much of concern. Higher outputs such as seen a boosted application tend to break the 5's.
Not sure about the Sonnax. It would be interesting to know how durable they are. He was talking up TQ and HP numbers beyond 600.
Very true about the converter being a game changer. My conversations with a Stock class drag racer, whose engine program is on par with my own in terms of overall output, is miles ahead in track performance. His one sentence sums it up. "It's all in the transmission and converter". Lightweight components in a TH350 and a converter that keeps the engine in a 1000 RPM window gets him down the track in a hurry. There's more to it than at obviously with those Stock and S/S class guys chasing every bit of friction reducing tactic possible but the transmission statement stuck with me.
Sonnax makes a 6 pinion planetary gearset set that changes the ratios for 1st and 2nd gear to make the 700 R4/4l60 a close ratio transmission..
That's a direction I may have gone had I been better informed when I put this latest transmission together several years ago. The big ratio split, without a good converter, kills track performance.
I didn't see a spec on power limits other than "Manufactured and engineered for outstanding durability". Any idea?
I'm not sure what they are rated for. Sonnax makes nice products though. The OP does transmissions for his day job and said he has sold about 100 of these. He should know about them.
My "race" converter stalls at around 6000 RPM. I launch at 4500 rpm as that's roughly where I make peak torque. I use a transbrake so launching at a high rpm is easy. With the 2 speed powerglide, I only have one shift to make. I shift at 7200 and the rpm peaks to 7400 at the end of the shift. RPM drops to 6400 after the shift and I cross the finish line at 7400 rpm.
Driving around the pits, the converter slips a lot since I'm driving around under 6000 Rpm. I can put the car in gear and with just a little bit of throttle, I can easily drive around in the pits. Doing a calculation on a 1/4 mile run, I only have 8% slippage going down the track which is very good.
For a daily driver however, 3200-3600 stall speed is more than enough if there has been a cam change. 2800 with a stock cam.
After 2 years of owning my 92 B4C I finally got the chance to take it to the drag strip. Last night was the opening Wednesday test and tune at our local track, Muncie Dragway. I met up with some co-workers and friends to go knock the dust off. We had a pretty unique group. My 92 L98 B4C of course, a 99 Trans AM with a junkyard cam only 5.3 LS and Th400 trans, an 07 Colorado with a 5.3 and 88mm turbo with a TH400, 15 Z06 with a cam and full bolt-ons and a 00 SS Camaro with a 5.3 80mm turbo and Th400.
I haven't done any modifications since purchasing the car. Just some maintenance ect. No timing adjustments or anything. The car has a pair of SLP runners and edelbrock headers for sure. The previous owner claims it has a Comp-u-cam in it, but Im not sure. I wanted a true baseline run out of my B4C. So I drove it over and pulled right in the lanes. First pass was 14.61@94.8mph with a 2.01 60ft. The pass went really well other than late shifting. It hooked really well. Shifted around 4700rpm out of 1st but wrung out to about 5300rpm out of 2nd. I let the car cool off for a bit and helped my friend make some runs in his 2000 Camaro. It was a pretty rough first night at the track. One guy lost his brakes and ran off the end of the track rolling 3 times. A second guy ran off the end but I never heard what happened to him. Then a 3rd car turned the engine inside out and spit a bunch of rods on the track. Then drove over his own oil and brushed the wall. Once all that mess was over I got to make one more pass. I left a little harder but still had the same 2.01 60ft. It shifted good on the 1-2 shift around 4700-5000rpm. But on the 2-3 shift it really hung it out to about 6000rpm. The car nosed over and lost some time. I had to lift slightly to make it shift and ran a 14.47@95.8mph.
So Im going to pull the governor out of the transmission and see if its sticking or broken. Id really like to get a low 14 second pass out of the car before I start making any changes to it.
Sounds like a fun day at the track! I raced a few times at Muncie Dragway a long time ago. When my 91 Z28 (L98/G92) was 100% stock it ran a 14.22@96mph with a 1.99 60'. I always felt it would have been pretty easy to get it into the 13s or even 12s. The L98 G92 cars run pretty well for what they are. I'm sure a looser converter and sticky tires would really wake it up along with doing a few things to help it breath a little better.
05-02-2024, 09:00 AM
