Harry's GPS Suite Forum

Hi

Within the Harry's Lap Timer, or other products, do we have the ability to give a shift light and buzzer at a specific (or several specific) speeds.

It is to fit in our Diesel Drag Car

http://www.darksidedevelopments.co.uk/a ... 0-16v-bkd/

We cannot use RPM as in 1st and 2nd gear the vehicle hits the 6000rpm fuel cut for several seconds until we get grip. We know the shift point speed from calculations between the gear ratios, tyre size and torque curve.

If this is not possible, any other suggestions of how to achieve this would be great.

Thanks

The shift flash can be set by RPM only. It is a visual feedback, you may consider simply ignoring it for the 1st and 2nd. There is no workaround I could think of currently.

- Harry

We cannot use RPM as in 1st and 2nd gear the vehicle hits the 6000rpm fuel cut for several seconds until we get grip.

If you're getting that much wheel spin, you need to work on your launch. Wheel spin is wasted time and money. If it's clutch slip, it's still money.

gplracerx wrote:If you're getting that much wheel spin, you need to work on your launch. Wheel spin is wasted time and money. If it's clutch slip, it's still money.

OT but for that kind of fwd car and power output you will always have and in fact need wheel spin. First it's proven that having some wheel spin will in fact make you faster than no wheel spin at all and secondly it's kind of the only way to mantain boost hitting the limiter while the speed catches up with the wheel spin. Take this car as another example, it's one of the fastest fwd cars in Europe and you will notice lots of wheelspin in 1st and 2nd:

[youtube]https://www.youtube.com/watch?v=dqSRrwLZo-g[/youtube]

@Darkside:

I'm not that informed on Diesel drag racing, but even if you're still using a re-mapped BKD ECU I guess it might be too old since OBD2 was introduced to Diesel cars around 2002 / 2003 and Laptimer needs a OBD2 compliant vehicle bus for things like RPM. Even if it's an early OBD2 compliant engine, the refresh rates will be to slow for such a hardcore environment.
Laptimer however has a speedometer view. Combined with an external GPS receiver with at least 10hz or even 20hz refresh rate it might help you achieve your goal of shifting based on GPS speed.

Wheel spin and slip are different things. Maximum traction for a dry surface is achieved at about 10% slip, i.e. the wheels are turning about 10% faster than the actual speed. But they are still hooked up. Wheel spin means smoke and very little grip. I didn't see any wheel spin in the linked video. If you're hitting the rpm limiter during launch, you're doing something wrong.

Maybe one day you'll explain what's wrong with you...[emoji15]
In this thread you introduced the term "wheel spin" and I simply stuck with it. In fact I know the difference between slip an wheelspin, at that moment I didn't think about it and after all I'm not a native speaker...what about you start posting in German so I can be picky about tecnicalities. You didn't even try to help or answer the question but decided to go straight to "you're doing something wrong". You seem to have quite some knowledge on some freaky stuff and this forum surely profits from your elaborate threads...but to tell somebody who has "home build" a 10s Diesel Seat Arosa with a 1,9l engine he is wrong???
I guess here in Germany the street legal drag racing scene kind of really started after the first Fast and the Furious movies. Suddenly there were events on old air fields you could enter with your street legal car or whatever you had build in your shed. I've visited quite some of those events over the years and by now those home build compact cars are doing 8s times. What do I want? Well, all of those cars are hitting the limiter or fuel cut or whatever in first and even second gear and have quite some slip...so everybody in Germany (or even in Europe since Darkside is doing it wrong too according to you) is doing it wrong [emoji23] Come on man, these aren't top fuel dragsters but mostly hand shifted cars people are building themselves, reaching up to 1200hp from 2l engines. Not bad for those "noobs". Did you even take the time to go on Darkside's site to at least watch some of the videos...I'm pretty sure you haven't seen a Seat Arosa before and definetely none like this one.
I'm sure this post is full of mistakes...let me know [emoji6]

BTT

@Darkside

I just remembered some GPS based speedos I came across...getting you away from HLT though

http://www.speedhut.com/gauge/GRM4.5-GP ... m-h-Metric

That's just one example, they come in all forms and sizes and can even be customized. I know 180kmh is lower than the achieved top speed, but that way you have a higher "resolution" for the analog speedo. The gauge comes with an extrenal GPS antenna you can mount to your roof and basically just needs some electrical power to run. It still lacks the flash light function but it might be an alternative for you, here's a video:

[youtube]https://www.youtube.com/watch?v=GgHV3v7ZYDM[/youtube]

bulls23,

Sorry I sounded so negative. What I meant was that there may be more to gain in terms of elapsed time in the launch and second gear than optimizing shift rpm for higher gears. The cars are impressive. Oh, and I can't launch my Mustang worth a dime. I either spin the tires or bog.

Just to make sure I'm (or we) are on the same page:

I thought his problem is the slip in 1st and 2nd and being in the fuel cut for some seconds and therefore there's no use in shifting via tachometer and shifting at too low a speed results in ending up with now boost from the turbo. Therefore he was looking for a speedometer that again isn't affected by the slip, hence GPS based speed, ideally with some customizable shift light or beep. Knowing his gear ratios and the wheel size etc. he can calculate the speed where he should shift from 1st to 2nd and maybe 2nd to 3rd without ending up in the turbo hole.

With the GPS Speedometer I suggested, he can at first shift at certain calculated speeds measured by GPS and later on use his tachometer when slip is gone.

bulls23 wrote:Just to make sure I'm (or we) are on the same page:

I thought his problem is the slip in 1st and 2nd and being in the fuel cut for some seconds and therefore there's no use in shifting via tachometer and shifting at too low a speed results in ending up with now boost from the turbo. Therefore he was looking for a speedometer that again isn't affected by the slip, hence GPS based speed, ideally with some customizable shift light or beep. Knowing his gear ratios and the wheel size etc. he can calculate the speed where he should shift from 1st to 2nd and maybe 2nd to 3rd without ending up in the turbo hole.

With the GPS Speedometer I suggested, he can at first shift at certain calculated speeds measured by GPS and later on use his tachometer when slip is gone.

That sounds reasonable. I think that's what launch control is supposed to do. Although with a 2 wheel drive car, you can compare the wheel speed of the driven wheels vs the non-driven wheels to control the power applied. With four wheel drive, you would need an independent measure of speed like GPS and possibly include acceleration as well. Ideally, you would have the launch control controlling the clutch as well to keep the engine in the power band. I suspect this sort of thing is why a lot of drag racers in the US use beefed up automatic rather than manual transmissions.