Autocrosser, a question

[milehi914]

I have been evaluating my other weekends performance at the local autox. I was coming into a 25 pace slalom at about 4500 rmp and could accelerate up to about 6000 in 2nd, I could have accelerated more (I think). So, my question is do you guys find that you have enough torque in 3rd to still pull through corners and slaloms? I got stuck going for time and ended up not trying for third. Advise will help for next opportunity.

Any Denver 914ers on this board. Would like to see you at next autox to give the Miatas a run.

[John Rogers]

When to shift is a tricky question since your competition may never give you the straight scoop? You have to weigh several things during a run such as is the car still pulling hard in the gear even though RPMs are still climbing? I was with a student at our last auto-x and I could actually feel his car's accelaration drop off after he went past about 5200 RPM but he kept the same gear. Next is will you gain or lose time due to the shift? Since 901 transmissions are somewhat slow shifting, will the accelaration lost during the shift be made up by the extra accelaration from the next higher gear. Finally, if you do shift up, now you have to down shift sometime at the turn so the car will not lug at low RPMs in a too-high gear and this takes a lot of practice. All this is exactly what you are questioning and the only way to tell which is fastest is by the clock such as an automated system which many organizations do not have or there may not be enough timed runs to really evaluate the different methods of taking the course. Personally I have found it better to shift a little early and use the torque of the type 4 motor to get a little extra speed whenever possible. Good luck.

[HMeeder]

You've got a whole lot of variables that aren't really covered in your post. How soon after the slalom would you have to be downshifting? If you got 3rd, how much speed would you be carrying when you did have to downshift? What motor are you driving, a modified 2 liter pulling 150 horses or a wheezing stock 1.7 motoring into a headwind? John's reference to a type 4's torque won't apply to all of us. His car is a severely modified race car that actually has a ton of torque (and his tranny isn't stock either!) while the rest of us have trouble geting out of our own way.

5000 in 2nd equates to around 3400 in 3rd on my car and for me that is getting right into the fattest part of my torque curve. However, due to some of the slow shifting issues that John mentioned, I might be tempted to stay in 2nd if you would have to shut down into a type 1 turn immediately after the slalom. It would also depend on if I could get to 3rd before the 1st cone of the slalom. I don't have the skills or experience to shift in the middle of that kind of combination. The car is transitioning through so much at that time, I couldn't imagine adding a shift to further unsettle it.

But then again, it may work out great for you!

Good Luck and keep tearing those tires up!

ps PCASDR AutoXers: see you Saturday at the Q!

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Herb
'72 1.7 Tangerine 'Teen
'74 2.0 Red Rustmobile

[milehi914]

Thanks for the replys guys. I have a big bored 1.7 (soon to be 2.0). In terms of coming into the slalom in 2nd I would have been around 4500rpms or so. So putting it into 3rd I would have been down around 3000ish? That would be right before I started to turn for the first cone. I found myself using the accelertor to help me move through the slalom. Maybe not the best practice but I recently put on stiffer shocks and 140lbs springs in the rear and have not got to the front yet (winter project) therefore very tail happy. It was a 7 cone slalom followed by a very short straight into a very tight, should be in 1st but second will have to do because there is nooo way its going into 1st, corner. I have been placing 6th out of 9 for the past three events and .25 seconds, or so, would move me to 4th. Damn those Miatas. Needless to say, I was wondering if I could pick up that time with a little more speed through the slaloms and transitions.? I will eventually have to give it a try but with only 3 runs and trying to move up in the placements I am having trouble making myself try it. Thanks for helping a rookie out.

[Dave at Pelican Parts]

The only way to know for sure is to try it out yourself.

The stock 1.7 and 2.0 are actually pretty torquey--they both make considerably more lb-ft of torque than they do HP of power. (80 HP / 99 lb-ft; 95 HP / 105 lb-ft) So they will both have some oomph, even at low-ish revs.

In the stock 2.0, the power falls off very quickly after 5000-5200 RPM or so. Unless you take a very long time to shift, you'll probably come out ahead by going to 3rd versus spinning the engine up to 6K RPM. But it does depend on a whole lot of other things... Try it and see what you think.

If you're looking for other 914 pilots in the area, check a Civic for a co-driver named Josh Hadler. He used to flog his 74 2.0 around, but it started making Really Expensive Noises one day, and he had to park it. He's a pretty good driver, and was doing reasonably well in his dark-grey 914. If SCCA allows it, you might ask him to ride with you to give you some feedback.

Oh, and throttle steering in a slalom is not necessarily a bad thing!

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[oredith]

why won't you shift into 1st around the turn?.. because the tranny won't take it?.. or there isn't enough time?..

the last irwindale auto-x i took the 914 to, i was taking this hairpin in 2nd for a couple of laps.. and when i finally gave in, and dumped it into 1st (glad i can heel-toe, the tranny would NOT have liked that shift), i shaved 2 full seconds off my time..

just to show that a gear *may* be the difference..

Jeff