Steve_A
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!!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
Hi guys,
So the car is a manual NA SW20 1991. I need to know what the speed at 7000RPM would be in each gear so I know when to change gear for a track day this Sunday.
I had hoped to fix the issue today by putting in a turbo cluster I had lying around and which I was told should work but now its in and the Tacho still doesn't read. I'll check the capacitors on both clusters to see if that is the problem but I have no experience with electronics so I definitely won't get this done by Sunday :(
So if anyone knows top speed for each gear or can show me how to calculate it using the ratio's that would be a big help! Shifting by ear is fine for DD but not ideal on the track haha
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Steve_A
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/29 13:04:07
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Falcon
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/29 13:35:29
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3 .944 is almost certain as final drive ratio.
Gen 3 Rev 5 Owners manual states. Max speed in gears. 1st- 61 2nd- 102 3rd- 152 4th- 196.
So easy to member- 50 100 150 200 done.
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B24
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/29 19:33:30
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Just change gears when the power drops off. Its around 6k. Will save a lot of effort.
BTW, best of luck with the trackday!
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dasic1
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/29 19:47:17
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Have to agree with B24, no need to rev past where the power drops off
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artymr2
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/29 21:21:17
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Yep as above. And you can always take it to the rev limiter if you want to know absolute max revs/speed.
Cheers
Black SW20 GT Turbo T-top 
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Steve_A
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/29 23:08:45
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Thanks for the advice guys! Putting 6000 into the calc gets me:
1st - 55 km/h
2nd - 92 km/h
3rd - 137 km/h
4th - 176 km/h
5th - 221 km/h
Just one more question, I have 4-1 headers which supposedly shifts the powerband upwards, should I compensate for that or do you think it won't have too much effect?
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artymr2
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/30 01:43:52
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Don't worry about the power band shifting potentially by a few hundred rpm, I would concentrate more on learning and perfecting your car's handling, cornering, heel and toeing etc.
Also be mindful with a helmet on and the noise of other cars nearby, the sound of the car is quite different and it's easy to hit the rev limiter until you get used to it. That's what I found the first time I went on the track.
I'm regard to your tacho not working, isn't the cluster fed a signal from the ecu? Could be a broken wire/connections.
Cheers
Black SW20 GT Turbo T-top
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Eric
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/30 03:14:50
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I did my first track day a fortnight ago, and I just went by the feel of the power band. I couldn't really hear anything through the helmet so I would just wait for the end of the power band and shift accordingly.
as for the cluster, did the NA one that was in previously move at all? even the slightest? if so, it will be a capacitor issue
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Steve_A
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/30 11:19:58
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I definitely have a long way to go as far as driving skill is concerned haha! I'm finding it hard with heel and toeing to maintain even brake pressure, when I hit the throttle I also push harder on the brake and I feel like it upsets the balance of the car a little. Practice makes perfect I guess!
I'm pretty sure the tacho is run of a signal but the speedo is mechanical since my car is an early model. When the tacho went it used to move a little and hot or cold would change how much it moved. I didn't worry about checking the capacitors because the odometer was broken (dodgy mechanic wound it) so I just got a new cluster.
With the new cluster the tacho jumps up a little on startup but thats it. And the temp gauge doesn't work either! I'm going to pull it out again today and make sure I don't have a loose connection, but if not I'll put the old one back in for the track as I definitely want to know if the engine gets too hot.
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Eric
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/30 11:57:31
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The capacitor replacement job is really easy, its a 50c capacitor from jaycar and a little bit of solder. I hadnt had any experience at the time but did it in less than an hour!
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Reddtarga
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/30 15:41:34
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Steve_A
I definitely have a long way to go as far as driving skill is concerned haha! I'm finding it hard with heel and toeing to maintain even brake pressure, when I hit the throttle I also push harder on the brake and I feel like it upsets the balance of the car a little. Practice makes perfect I guess!
Are you using racing boots? They can give much more precise pedal/throttle control.
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Steve_A
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Re: !!!No Tacho Need to get RPM from Speed in gear for Trackday!!!
2014/08/30 22:37:09
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Just been using a thin soled shoes, I'll have to grab a pair!
I realised I had an ecliptech shift light lying around which would have been perfect for the track! Tried installing it while I replaced the old cluster but couldn't figure out which line was the igniter signal or which one to use as a power source so I gave up on that :( Need more time and someone who knows what they're doing haha
Having a closer look at the back of both the NA and Turbo clusters revealed differences in the circuits which are responsible for the temp guage not functioning. Could maybe be made to work if the pins in the connectors are switched around to the right config but it is not a plug n play swap! At least for the early mechanical type clusters.
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