Aftermarket Tach

[Preloader]

Yes you read it right. Before I get bombarded with Paul Walker memes, let me explain.

The stock tach has a lag that you wouldn't believe. I shift when I see 5.5k, and my logs show I'm shifting at 7k.

I hate the idea of having two tachs, and would consider making the 2nd one a take-off that I would just use at the track.

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[Wong]

I have always used autometer

 

[$ub$onic]

That's interesting. I would go through the ug to find out if its in the sensor or the tach it's self. I

 

[Preloader]

The problem with the UG is that the display is so small that it would be dangerous to look at when ramping up to 6k.

TriVince says the stock tach is very accurate at slower engine revs, but it lags horribly when the engine is wrapping up.

 

[$ub$onic]

I agree it's dangerous. But just for testing it might help.

 

[Preloader]

The logs don't lie. hahaha

Said I was shifting at 7k when I saw 5500 on the tach.

The stock tach gets it's digital signal from the ECU. The ECU is just like any other computer in that it has a finite amount of processing power.

Being that this is not a sportscar, I think the ECU delegates its bandwidth to the 30+ sensor loops, while the tach signal falls by the way side.

An aftermarket tach will bypass the ECU and get signal directly from the coil. This is gonna solve my problem completely.

 

[$ub$onic]

That's kids funning your out revving it. Anything Vince can do to alter the ECM to give the tach skittle higher priority?

 

[Preloader]

Not likely, I suspect its a processing lag.

 

[sx sonic]

Hmmm how long have you been outrunning your tach?
This would be a big candidate for your ET.s being below expectation (which I figure you already figured)

 

[Macehammer]

Could this have something to do with the alt. gearbox you are running?

 

[Preloader]

Wow. I didn't even consider that.......

But it shouldn't matter. Rpm is rpm. But I will investigate that idea.

And I believe the tach lag has gotten worse with every increase in power I've done.

 

[sx sonic]

Makes sense and is ironic.

"keeps increasing power to become fastest sonic"
"tach lag results in shift points with inferior power"

 

[wingman]

I think with all the sensors the computer has to monitor, the tach loses priority to those others detrimental to the drive ability of the car. At such high rpms there is a lot of processing going on. I think Paul walker is spot on. At least it sounds good. I want a ricer tach! I have no idea what a meme is or else I would post one.

 

[rdss]

Wow. I didn't even consider that.......

But it shouldn't matter. Rpm is rpm. But I will investigate that idea.

And I believe the tach lag has gotten worse with every increase in power I've done.

If you're shifting at 5,500 rpm indicated and in actuality shifting at 7,000 rpm you've just revved out 1,500 extra rpm all of which has shown to be out of steam even with the tumbler removal. If you don't get the tach in before the next run shift at 4,500-5,000 rpm to try and stay in the meat of the power band. If you go with with a second tach (removable or not) get one with a programmable shift light to aid in proper shift timing.

 

[Swordsmith]

Would it be possible to mount the new tach right over top of the current one? I like the placement, but I agree if it is uninformative there's no real point in hanging onto it. And I don't really like the idea of a second one.

UG and/or Torque can have much larger displays if you are interested in only a single point of information; in other words if you want to see just Tach, you can make that take up the whole screen. BUT they both get their info from the ECU as far as I know, so I don't guess there's any real point in moving to one of them for that info.

Of course if the new tach really works and helps, the next step would be to replace the current display since it would be just wasted weight at that point... except there goes all the other fancy lights. How much do we care about each of those?

Headlights: I leave these on auto so they are always on, this light doesn't tell me anything
High Beam/Low Beam. I care a little... I rarely run high beams so I probably don't care much.
TC/Stab me in the eyes Control activated... easy, remove ABS fuse and this isn't a concern anymore
Seatbelts: Is this one on the tach? Anyway, bonging sound so I don't need the light
Door open: see seatbelts, although this one IS on the tach for sure. I can do without.

What else is on there, anything we really want to know?

Oh, Cruise Control. Yeah, um, I sort of want to know if it's on (which tells me if I'm in red pill or blue pill) and if it's active.

 

[Swordsmith]

Thinking about this some more, aren't RPM and Speed directly linked? Can we just say 'to hell with the tach, shift at speeds X, Y, and maybe Z?'

 

[Preloader]

Thinking about this some more, aren't RPM and Speed directly linked? Can we just say 'to hell with the tach, shift at speeds X, Y, and maybe Z?'

Actually, yes, and that is a fine idea. I wish it was mine.

I could just shift a little earlier based on mph until I found the sweet spot.
I like it, and will try that in combination with the accurate tach I install.

 

[Preloader]

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Or B

 

[d.p]

Autometer
Cobalt aresick tachs!

 

[Opticon]

Being that this is not a sportscar, I think the ECU delegates its bandwidth to the 30+ sensor loops, while the tach signal falls by the way side.

Being that this is not a sportscar, your concern about tach accuracy seems ridiculous.