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The mkiv Supra Owners Club

Removing rev limiter


dude

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See if you'd gone for the AEM, you could set the rev limit to whatever you liked....

 

OK so nobody can tune the damned thing yet (save pete betts), and it would make changing gear on the auto's a bit tricky, and may be responsible for blowing at least one engine, but rev limits, not a problem! ;)

 

Basically, I think you're going to struggle, because the ecu needs to know what the revs are to relate back to the fuel/ignition maps, so clamping the rev signal going into the ecu is going to mean you'll only get fuel/ignition up to whatever you clamp the signal to. I don't think it's possible to re-programme the mines ecu is it? (I'll stop teaching granny to suck eggs now...)

 

Having said that, aren't there piggy back boxes available that claim to be able to alter the rev limit?

 

What are you thinking, larger turbo but higher rev limit, and just drive it higher up in the rev range? Could be cool!

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Nic,

 

I think those products only give you a 2 step rev limit. This means when you put the clutch in, or hold down a button (or any switch for that matter) the rev limit will be whatever you set it to, say 4000 rpm. Then when you let go of the button the reve limite returns back to whatever the main rev limit is. Basically used as a form of launch control. (Plus it means you can build boost without actually moving - if somone can explain how that happens I'd be much obliged!)

 

Having had a think about this, I really can't see anyway around not re-programming the ecu in some way, whether that be sending the ecu to be re-programmed, or having a piggy back ecu that gives you fuel and ignition maps above whatever the mines ecu limit is (I was going to suggest something like a Dastek pggy back, but I don't think you can raise the rev limit on that either, as all it does is modifies the outputs from the ecu by +/- x%. Once you go above the programmed map and get zero output +/- X% = zero, so still no use) The problem is that I doubt very much that mines worked out fuel/ignition maps to say 10K RPM, when they were going to set a rev limit of 7,400. Maybe they did, don't know....

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what is a safe rev limit for stock internals 8000?

 

you have the upgraded springs and retainers what can you rev to with them in place. looks like a standalone ecu will come into its own for tuning. do any of the other single turbos run higher rev limits. is it because you running out of revs going down the 1/4

does it bounce off rev limit with been a mid size turbo

 

in that vid you seem to launch well with no wheel spin.

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Originally posted by migster

ProSpec are Mines dealers in the UK it might be worth having a word with them?

 

 

Sorry someone has allready said this:stupid: ill shut up now

 

ProSpec wont work on any Mines product they havent supplied , pants isnt it !!!

 

Dude:flame Dev

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Its gonna be interesting Mr Mole , im gonna do a test and tune day at the Pod along with Tango man, i'll prob try the manual gearing as well as a few other tricks and then get CJ's car running as fast as poss .

 

Dude:flame Dev

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Originally posted by dude

Its gonna be interesting Mr Mole , im gonna do a test and tune day at the Pod along with Tango man, i'll prob try the manual gearing as well as a few other tricks and then get CJ's car running as fast as poss .

 

Dude:flame Dev

 

Hmmm good idea. If it were me I would want to do three runs.

The first would be as the current set-up.

The second would be raised rev limit, with current gearing.

The third would be with manual gearing.

 

In fact I'd probably do three of each run and then take an average time.

 

Really it depends on how much your going into OD. If it's more than a couple of hundred RPM (Say 500) then you're going to struggle to get that back by changing the diff alone I would have thought. I agree with Matt about longer gearing helping traction, although with regards to engine efficiency ranges, I would have thought that would simply depend on the size of turbo with as large as possible (and hence higher RPM's to solve the spooling problem, and the fact it's going to want to make peak power later on) would be the order of the day. I guess it really depends on your set-up, which I must admit despite all the recent hype, (deserved as it is!) I know very little about.

 

I would love to see a really good back to back of all these. Nice and scientific like ;)

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Originally posted by Terry S

Now me and electronics don't get on but could you not clamp the reading the ECU sees, similar to the FCD principal?

 

Unfortunately not, as the ecu needs to know what rev's the engine is doing to work out where it is in the fuel map.

 

Errm imagine it like a table, with revs going along the bottom and boost going along the side. The values in the table are injector duty amounts. So at 2000 rpm, and 0.5 bar boost you would need 20% duty cycle. If you go up to 8000 rpm, but the most the ecu ever sees is 5000 rpm (because you've clamped it to this figure), it will only ever give you the fuel for 5000 rpm.

 

Hence why if you want to do this you'll need to get an aftermarket programmable ecu. (Whether that is programmed by you or somone else. I don't think any piggy back's are capable of creating fuel maps beyond what exists, as they only mod existing maps)

 

Hope that helps. :thumbs:

 

Tony

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How about a custom Diff from Quaife? They could do any gear ratio's you wanted...

 

Also on the Quaife website is a gearing calculator which will help to decide what gearing is best for the powerband you're running.

 

Otherwise....I would have thought it was time to bin the stock type ECU...I thought Matt managed 8000 rpm on his Mines? I know I managed 7,500 (on the dial might not have neen true speed)

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I'm pretty sure Terry knows that ..............Is it not a case of clamping the signal at 74** rpm and then just reving 500rpm or so more to get across the line?

 

Obviously the ecu will be providing only fuel for the 7*** clamped signal.

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Guest Terry S
Originally posted by matt

I'm pretty sure Terry knows that ..............Is it not a case of clamping the signal at 74** rpm and then just reving 500rpm or so more to get across the line?

 

Obviously the ecu will be providing only fuel for the 7*** clamped signal.

Thanks Matt, c'mon Tony!

 

Clamp it at the stock limit. It won't be mapped past there anyway it will only use the fuel settings at the stock limit.

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However, my point is still valid. The difference in duty cycle from 7500 RPM's to 8000 RPM's will be a lot more than you'd want it to be. Can't remember exactly but I think the last 500 RPM on my fuel map sees the duty increase from 95 to over 100% (Not to worry as my rev limiter is set way lower than that anyway!)

 

What I'm saying, is you'd run 'orribly lean, at a point where you're at high boost AND high revs. I know my puny 440's will porbably be running a lot leaner than whatever gargantuam injectors john will be running, but he's going to be needing that fuel a lot more than I would. I suppose if money was no object, then that would indeed be the way to go, letting the engie let go as you charge over the line.

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