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2 or 3 step rev limiters built into MJ
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Post 2 or 3 step rev limiters built into MJ 
Some of us drag racers would love to be able to use a 2 step for launching such as this http://www.msdignition.com/Products/RPM/Timing_Controls/RPM_Controls/8739_-_Two_Step_Module_Selector.aspx
Any possibility of incorporating something like this?
Or this? http://www.npcompleteperformance.com/wotbox

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Interesting. Could this also be a stand alone system, which can add programmable rev limiting on any system (distributor, wasted spark, etc)? I've always thought the rev limiter module could become it's own stand-alone unit.


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Brent Picasso
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Intriguing... then head hit into overtime and use it as a kind of autochoke?

If it's programmable on specified inputs? Versatility is King! Very Happy

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On non DIS applications it is usually an add on box that plugs into the side of MSD's box. It plugs into the slot where the rpm chips/pills would plug.
For DIS applications such as GM and Ford you would have to use an MSD Digital box DIS. This is how many guys with Buick Grand Nationals and later model 4.6 liter Mustangs have been doing it. I am not an electronics guy and thus I ask the question of whether its possible.
Is it possible to utilize an MSD box with the Megajolt?

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So looking at those devices they provide launch control by detecting clutch position and and throttle position. This would be fairly easy to do with Megajolt2, due to the additional inputs and outputs it provides. The MSD unit seems to be specific to plugging into the MSD ignition systems, while the WOT box is more universal in nature.

A dedicated stand-alone rev-limiter / launch control could be developed as well. If such a thing existed what would be the desired feature list / capability list?


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Brent,
The benefits from my stand point are more consistent launches when drag racing.
Example:
Your launch rev limit is 4500rpms. You turn on the 2 step. Pull to the line and floor it. The engine will not go over 4500 rpms.
You release the clutch. When you release the clutch it switches to the second rev limit of say 6500 rpms which would be your failsafe incase of an engine over rev.
A 2 step can also be used on automatic transmission vehicles equipt with a trans brake. Many guys have it hooked to their trans brake and launch the same way. The release of the trans brake causes it to switch to the second rev limit.

Major benefit of a two step on a turbo charged vehicle with a manual trans is to load the turbo causing it to start producing boost on launch.
If you could do it you could also potentially incorporate a timing retard on launch that would also help with turbo spool up.
As a side note......if you have ever watched drag racing and heard cars sounding like the engine was stuttering on the launch then you have witnessed a 2 or 3 step. Some people call it a "stutter box".

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An inquiry into our sales email made me realize this would be a very easy thing to do with a megajolt unit.

Could someone with a megajolt & hard rev limiter test the following idea?

Rev limit ouput set at whatever engine RPM limit is.

An extra user output is routed through a clutch activated switch such that the switch is closed when the clutch is depressed. Say you use user output #4.

Code:

user output 4 ---- clutch switch --- \______________ Hard Rev limiter trigger
rev limit  ------------------------- /
[/code]

Setting user output 4 as an RPM activated switch at say, 4000 RPM will give you that rev limit while the clutch is depressed.

Who wants to try this out and document their findings?


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Apologies if this is a bit simplistic and if it's waaaaaaay of mark... and I haven't got to grips with the options of Map programming yet, however, whatabout create one map with a fixed rev range, and a switch on dash wired in parallel to a switch on the brake/clutch (however launch is initiated) then use the settings in the hard rev limter as the second stage?

On the line - Map 1 (launch map) is in action, on clutch dump switch triggers map 2 and the MJ is then RPM limited by the hard rev limiter?

Again, apologies if that's too simple and not possible.

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Yes! Using a switch wired to the option input could work too- However, that might encumber other uses of map switching, such as tuning for different octane fuel, etc. I was thinking that combining multiple outputs could get you additional flexibility by incorporating the clutch switch as external logic of sorts.


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I knew I wasn't mad, lol.

How stable is the programming on the EEPROM once power has been removed? Does it disappear? Maybe follow the Nintendo route and have individual eeproms in cartridge form that you can plug in at will dependant on setup required? Use the existing board, with a breakout module to house the cartridge. Just a thought Smile

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Actually, the maps are written to flash, not EEPROM. And it's quite stable! You can look at the Freescale data sheets, but (i think) the retention is supposed to be measured in decades.


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Brent,
I just received my MegaJolt last week. Unfortunately I didnt specify the rev limiter. Would it be possible to send it back and have it added?

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Looking through old posts atempting to find a 2 Step upgrade, and what do I find?
This here thread.... Did anyone attempt this idea?... Was it successful?... Got any tips, setup diagrams or pics of e install..... I'd so love to fit up someing like this to my turbo charged Bug.

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