I've been diagnosed with acute racing fever...

Discussion in 'Race 400/430/455' started by ravensbud, Jul 24, 2018.

  1. ravensbud

    ravensbud Silver Level contributor

    So last weekend I got my first shot at racing 1/8 mile on a real track with lights and timers and all the fancy stuff. I venture to say its the most fun you can have with your clothes on! Having never done this before I made several passes to set my dial-in time for bracket racing. Below is the time slip for my first elimination round in the big money race. I'm on the left...

    I've got some newbie questions:
    1) Mr. Stevens cut a perfect light on me in my first race ever!?! Is it correct to figure that if I had cut a 0.15 or better I would have won since he only beat me by .052?

    2) Everybody I raced was just blowing me off the line and my elapsed times were not nearly as fast as I thought they would be. It was quite a rude awakening, and now its all I can think about. That 60' time is dreadful, although guys were telling me it was pretty respectable for a full interior car and stock gears.

    Here's the details:
    '67 GS400, original 2.93 posi with M/T drag radials (26x9.50R17).
    TSP built 470 with Stage2 heads and 2-1/2" x-pipe with cutouts. Sparing you all the gory details, it made 580hp/562tq with stock rockers, maybe just a tad more now that I've added roller rockers.
    ST400 with a TSP modified 12" converter and Bruce Roe control box.

    I was getting good traction off the line, shifting at 5800 and crossing the finish line at ~5200 in 2nd gear. I suspect the car is such a dog off the line because of the 2.93 gears. Am I right about this? For argument's sake let's say I built a new rear end with mid to high 3 gears and added a Gear Vendors overdrive (for sanity on the highway). Would my 1/8 mile time improve dramatically, all things being equal? Or would it not be worth the hassle and expense for only modest gains?

    Maybe someone can cure me of this sickness before it really sets in....
  2. hugger

    hugger Well-Known Member

    Mr Stevens trapped 101 and went a 6.90,. You could have left over 1 full second b4 him and he would have still won

    A gear change may or may not help you Buicks are weird that way, it's all about staying in the meat of the power curve, but generally speaking yes a 3.73 gear would pick it up probably 2 tenths all other things being equal.
  3. Bens99gtp

    Bens99gtp Well-Known Member

    Gears make a huge difference in a car. We did a rear in a friend's 5.0l Fbody mustang. Basically stk motor with few basic bolt ons. Car was a 5 speed and ran 14.75 had a upper 2 or low 3 gears. We put a 4.1 gear in car ran 14.0s with a lot of tire spin.

    Based on your 8.250 1/8th mile that should be a 12.8x 1/4 mile. I would think given your hp level all these times seem very soft. But gears will make a difference.

    We ran a stk 430 bottom end with good iron heads, sp1, 1000cfm, 4.10, 4500 stall 3850 car and driver, 9" slicks. Car went 11.30s. I'm sure it wasn't making your hp
    Last edited: Jul 24, 2018
  4. telriv

    telriv Well-Known Member

    Don't forget the added weight of the gears vendors & associated weight of the components to install such unit. Weight is HP!!!
  5. Briz

    Briz Platinum Level Contributor

    After my first few passes in the Riv I got the fever also. However racing and my goals for the car were not compatible and its tough to get a 4500 sled down the track and make the numbers I was looking for. After a few years of reading here and asking questions the decission was made to build a track only car. I set a budget of 2500 do go into the 12's. After a yr of building and tweaking it went 7.80's/ 12.20's with a high 1.60's 60' on a lightly warmed up low compression 455 with stock heads. You may be able to find the thread from 2012. Captain America Skylark Lark Launch.jpg
    ravensbud likes this.
  6. 455monte

    455monte Well-Known Member

    Looks like mr stevens car isnt gettin the best of traction either.
    His mph of almost 102 at only 690s is high meaning hes spinning and the 60 ft time verifies that. U may want to give the traxk another shot as maybe it was just a green track that day and everyones numbers could have been slower than normal.
    As far as gears i always ran a 3.90 in my street strip 455 buick powered monte carlo combined with a pae 3500 switch pitch 12 inch converter.
    Car ran 7.60s with a 9.4 compression close to stock 1974 heads poston cam and poston intake. Probably 400 hp if even that much.
    Moral of the story.... correct convwrter and gears for your power band make a world of difference. Assuming traction is good. Adding gear will make a car spin worse if it already has a traction issue.
    The higher numerically gear the more torque multiplication. Just something to consider when choosing gears.
    And as far as a sickness u are correct!
    Fisrt u will want to be in the 7s
    Then before u know it u will be below 750s and need a rollbar then u will want to be in the 6s and so on and on lol.
    Ive been fighting this sickness for 15 plus years lol
  7. Jim Weise

    Jim Weise 1000+HP

    It's all about 2 things on the starting line.



    With your engine torque, it's not out of the realm of possibility to put that car into the 6's in the 8th. Without touching the engine.

    Had I know you were going to get the racing bug, I would have steered you away from the VP.. that's cool for the street, but the big huge converter, along with the relatively weak stall torque ratio, is not the hot ticket for the drag strip.

    You understand the need for traction, and these days, the parts are available to get the car to hook, even on a marginal track. Back when I was last racing a stock suspension car, we had drag slicks and 90-10 shocks, with special front springs, and an airbag in the RH rear coil... now you have some very good suspension stuff out there. A HRparts anti-roll bar, good shocks, a set of drag radials, and a few simple tricks should have you hooking solid.

    But now we need something to hook.. so here comes the math.

    Here's your dyno sheet

    dyno sheet stock rockers Q-jet as installed in car.JPG

    First let's estimate torque at 3000 rpm, where the VP converter should flash to... based on similar motors that I have done, and tested at that rpm, I would say we are at about 420 ft lbs at that rpm. We rarely dyno test at that low an rpm, because it is very hard on the engine.

    But let's work some math with that 420 number

    I will omit the trans ratios in this math roundup, as your not thinking of changing them.

    At stall, the stall torque ratio of the VP converter is about 1.2

    And you have a 2.93 gear..

    420x1.2x2.93 = 1476 foot lbs of power available to move the car off the starting line.

    The 9.5" converter that I would spec out for your car, would stall at 3300 rpm, or about the same as your current VP converter, but that converter has a stall torque ratio of 2.0

    More math:

    420x2.0x2.93= 2461.2

    With just the converter change, we picked up over a thousand foot lbs of torque! And allowed the engine to rev up faster, due to the 10lbs less rotating weight.. All while driving almost the same at light throttle, with your vp in low stall.

    Now let's go crazy..

    Gear vendor?... cool... don't waste your time with mid 3's gears.

    Let the big dog eat... 4.11

    so now...

    420x2.0x4.11= 3452 foot lbs to move that beast.. Hook it, and the front wheels are now getting daylight under them..

    We have effectively tripled the power available to move the car. And never opened the hood.

    So we understand the math now...

    It's actually even more than that, due to the fact that the deeper gears and lighter converter allow the engine to rev faster and better utilize the power you have available. Your going to be mid way thru 3rd gear at the finish line in the 8th.

    Good news for you is that I am sure your competent enough to change the front pump and converter on your car, I can provide you with the parts... and your current converter and VP pump assembly is about the same price as the 9.5" converter and fixed pitch pump... something to consider this winter..

    In the meantime, let's get what you have hooking, and then go practice your lights.

    And have fun!..that is the point of this whole deal.

    Last edited: Jul 25, 2018
    Houmark, 65Larkin, ravensbud and 5 others like this.

    MT BUICKNUT Well-Known Member


    His total package win was .052. Yes if your light would have been that much better you would have won.
    Thanks Rick
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I wouldn't sell the switch pitch 12" TSP converter short. I managed a 1.62 short time with it. I got my best ET (below) by wiring the converter to constant full stall. It did drop my trap speed by 1 MPH though. I always found that I got my best short times by getting as far up on the SP converter as I could holding the brakes, up around 27-2800 RPM. launching off idle was not as good in that respect.

    My current converter is a 258mm fixed pitch Ultimate Converter. It is nearly as heavy as the SP converter it replaced, and I could only tie my best 60' with it. Looking forward to installing the 9.5" converter I got from Jim. It is a full 11 lbs lighter.

    Last edited: Jul 25, 2018
    ravensbud likes this.
  10. cjeboyle

    cjeboyle Gold Level Contributor

    I absolutely love this post! I was reading this thread thinking He has way more power than I do, Why wouldn't he be quicker than that? Jim explained it perfectly.
  11. Bens99gtp

    Bens99gtp Well-Known Member

    My ultimate has not performed as I hoped either. I was very surprised when I called lenny and told him of our new combo, we swapped to our te2 ported heads should be make at least 125hp more maybe even 150hp, he said the converter didn't need to come back, he actually said it should fall right into the wheel house for the converter.........so to me that means it was either way off then or going to be now. Cause I really can't see how the same converter will be perfect for both motor combos?????
  12. Jim Weise

    Jim Weise 1000+HP

    I agree Larry, the 2.93 is really what is killing him. Not the worst gear for a stock motor, but not the hot ticket for a hot rod motor, from a standing start.

    I think he can work that 60' time into the 1.6's with his current VP setup, with more practice, and technique, with a gear change.

    Then I think 1.5's are in his future with a drag race converter.

    I think they are in your future too..

  13. ravensbud

    ravensbud Silver Level contributor

    Ok, you know you're all a bunch of crack-peddling enablers, right? All this talk of 6's, daylight under the front wheels, roll bars, tripling the torque, etc. I love it :)

    Jim, this post is outstanding. I always knew racers were fussing with converters and running numerically high gears, but the simple math showed me why they care so much about these two things. And it illustrates why my car is a relative slug even with a beefy motor. The car is a wonderful street car and set up to cruise down the Nevada Interstate where the average speed is 80+. I enjoy hearing the VP converter working as I'm part-throttling over hills and passing blue-hairs. But its not at home on the drag strip and now I know why. I never intended to make it a strip car, and still don't, but I'd like to investigate making it a strip car worthy of the motor while still eating my cake on the street too. I will never trailer this car anywhere.

    Which leads me to Larry's post
    For all intents and purposes, our cars were set up very similarly on our two timeslips. You've got a tad more motor and taller tire, I think. Probably a few other minor differences, BUT, that 3.73 gear seems to have made all the difference in the world....you were a full second faster in the 1/8th! Not being too familiar with the Gear Vendors yet, it didn't play a role in this, correct? You weren't gear splitting while racing, right? Funny that Ultimate Performance converter didn't help your 60' time. Why do you think that is? Does it have the same torque ratio of 2 that Jim mentioned for his 9.5"?

    Briz, I've got a "beater" '67 Skylark that I'm contemplating turning into a strip car. How did the Captain America experience turn out and are you still running it?

    A couple more newbie questions...the TSP 9.5" is a lockup converter, right? My VP converter is not, so all things being equal running down the highway at 70 I'd be turning a couple hundred RPMs less with the 9.5"?

    And finally, what specifically is the "powerband" of an engine....the area around the highest torque? Highest horsepower? The range between the two?

    Thanks all for the great info and learning opportunity, I AM having fun and dreaming of winter projects.
  14. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    If you can't beat this guy, you might as well join him!

    racing beaver.png
    A cute racing beaver!:D:D:D
  15. Briz

    Briz Platinum Level Contributor

    When it got to the point where I needed a cage I moved up to a better car that was for the most part built to the point where I was at. Would have cost me more time and money to put the work into the rusty lark. Found a roller Regal on Racing Junk for less than it would have cost me to build up the old car. Now Im about ready to do that again. Its a cycle.wash rinse and repeat.

    Attached Files:

  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    The 3.73 with the 28” tire reduces to a 3.55 effective ratio. Yes, gears are multipliers of torque, and the taller MT can mean better traction because of the taller sidewalls. I have TA no hop bars, and the HR parts n stuff rear sway bar. All this helps.

    The GV is not usable to split gears, it simply doesn’t shift fast enough. If you think about it, 1st gear gets split automatically as the GV comes in at 40MPH, but when you hit second gear, you have to turn the GV off to be in 2nd, not 2nd over, same thing for 3rd gear. It just isn’t possible to shift that on and off to split all the gears. What I can do and I haven’t is to leave the transmission in 2nd gear, and turn the GV on at the proper time so I go through the traps in 2nd over, the equivalent of 4.10 gearing. I love my GV, but I bought it for the OD. I have been told that it is slowing me down at the strip which makes sense as it is that much more to turn. Using the big heavy Buick wheels is costing me as well.

    Not sure why the Ultimate converter didn’t help me more, it drives on the street great and is efficiently enough for the GV, but one thing that bothers me is I can’t feel the WOT shifts at the track, the converter seems to soak them up, and that should not be at my 5800 RPM shift points. I can feel the shifts at normal street driving, but not at WOT. The converter should be coupled by then I would think. Looking forward to trying the 9.5” TSP unit.
  17. Bens99gtp

    Bens99gtp Well-Known Member

    Be great to hear the update on the converter change. When I went from 4 15x7 Buick rallye rims to 15x8 and 15x4 weld prostate and skinny front tires I gain no et at all.......I was super sad. I thought I would get something.
  18. Jim Weise

    Jim Weise 1000+HP

    Crack Peddlers??... I prefer to think of myself as a "Speed Merchant".. thank you very much..:D

    The 9.5"is a fixed pitch TH 400 converter, and just like your current VP unit, is not a lockup, as it does not have a physical clutch in it. No TH400 converter does, the trans does not have the internal controls for it. To get a 400 with a lockup, you have to go to the 4L80E, which is the 4 speed version of the TH 400, and I do have a 9.5" lockup converter for that with a triple disc clutch in it.

    The lockup converter, since you mention it, does in fact work with your plans on keeping it road friendly. I can actually build you a more strip oriented converter.. say 4000 rpm stall, and then when we lock up the converter, that stall does not hurt us down the road. It's the "have your cake and eat it too" idea, that the VP stuff was created for.. Stall when you want it, tighter (or in this case locked up) when you don't.

    Downside of any of these OD conversions is we really don't have the trans tunnel room for any of them. I know some guys have built a dropped crossmember to get more room up top, between the trans and the stock floor, I wonder if they are not sucking up a bunch of power with a driveline that is not running near zero under load. Hard to say, but guys have picked up time in the past by fixing pinion angle issues with the rear, and this is the same thing, albeit at the other end.

    I have done two installs of TH400 based OD's.. one was a GV with a 400, in a 72 Stage 1 Convertible, the other was a 4L80E in a 70 GS. With the ragtop, I actually shimmed up the body mounts, to gain about half an inch of clearance, which helped a ton, an you really could not notice it when it was all together. I did that in that car, because I was not about to start hacking up a one of 81 car.. I only had to slightly dimple the floor crossmember. Did it nice, looks factory..

    The 4L80 E conversion was considerably more involved.. it also needs more trans tunnel room, we actually cut and re-fit the tunnel in that one, to make it slightly bigger. This car was not a frame off like the convert was, and the body mount bolts looked a little Iffy, I didn't want to get involved in that broken bolt quagmire. So we actually swelled the tunnel up a bit, about n the middle.. put an extra "hump" in it, which ended up under the console. Unlike the GV unit, the 4L was not hitting on a floor cross-member, just sheetmetal, so it was easier to deal with. But that was the last easy thing.. at that time, there was no way to drive a mechanical speed, except an expensive conversion box, so we had to install that, and there was only one, rather crude, trans controller. The 4L trans is fully electronic, it shifts with solenoids, and a solenoid controls line pressure, another one controls the lock up torque converter. The brain box needs inputs from the throttle via a TPS, and from a map sensor to measure engine load. The crude TCI box was almost 2k alone, with all the wiring harnesses and accessories as I recall. The speedo converter (4L is designed only for an electronic speedo) was like $600 or something like that. Add to that a $300 core for the trans, and a $2400 rebuild (More parts to replace that are not cheap, and a premium is added by the parts vendors to the less expensive 400 parts it uses).. they get you coming and going... so it gets to be an expensive conversion.

    Now the good news is that the aftermarket has made good strides to making the 4L more friendly.. There are now aftermarket shift controllers that stand alone, for around $600, and a tailhousing that converts the trans to run a mechanical speedo.. still not cheap, the tailhousing conversion is like $500, but much less complex that the converters, with virutally nothing to fail down the road, but a cable..

    I have a chart laid out for the testing and transformation of the shop test car (70 Skylark custom coupe) from a stock GS 455 clone, to a 9 second street car, and one of the items in it's evolution will be the install and testing of first a 200-4R, and then when we break that, a 4L80E.. so I believe in OD transmissions, mainly because I like the lockup clutch feature.

  19. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    OK, I thought the drop in rotational weight might give you something. Any trap speed increase? Was it a direct comparison, same day?
  20. Bens99gtp

    Bens99gtp Well-Known Member

    Not same day, can't recall any mph gain. But I ran it for year b4 and years after with the same setup.

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