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Buell Motorcycle Forum » XBoard » Buell XBoard Archives » Archive through August 26, 2006 » Cylinder Head Temperature? « Previous Next »

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Trojan
Posted on Tuesday, August 22, 2006 - 05:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Does anyone have readings of rear cylinder head temp under normal (fast) use?

I am thinking of replacing the rear cylinder head sensor with a fixed value resistor set for optimum temperature. This is only for race use and will make mapping our adjustable ECU a little simpler.
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Davo
Posted on Tuesday, August 22, 2006 - 06:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Trojan,

My stock Uly ECM with stock scoops is running about 397-403 F in hot weather in which case the resistance of the ET is somewhere between (463 ohms @ 374 F) and (303 ohms @ 410 F). Many of the race ECM and/or right side scoopers are running cooler temperatures. In some cases their fans have cycled off during key on conditions which would indicate temperatures less than 356 F which is somewhere between (638 Ohms @ 338 F) and (463 ohms @ 374 F). Good luck and keep me posted.
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Bumblebee
Posted on Thursday, August 24, 2006 - 11:24 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

On my Cityx the rear cyl. head temp after a long fast run is about 375 as taken with a cheap IR (non contact) thermometer. In stop and go traffic I have seen it get as hot at 425, in both instances the fan is running at high speed.
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Fullpower
Posted on Thursday, August 24, 2006 - 01:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Trojan: why not use a precision ten turn potentiometer, with which you can dial in any fixed value you wish, and expect it to stay relatively stable?
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Xb9
Posted on Thursday, August 24, 2006 - 04:18 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I don't know if that would be a good idea, my understanding is the ECM compensates the injector pulse width for engine temperature - and when the engine temperature sensor says things are getting really hot it will richen the mixture to help cool things off (to a degree: ))
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Slaughter
Posted on Thursday, August 24, 2006 - 05:32 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

XB9- the full race module operates in open loop mode only.

I believe the stock and over-the-counter race modules operate closed loop like you described.

(Message edited by slaughter on August 24, 2006)
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Xb9
Posted on Thursday, August 24, 2006 - 11:43 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The programable race ECM software (Kimball race DDFI) has all the settings to be able to run as a stock ECM with closed loop & O2 sensor, but typically everyone that uses it for racing:

1. lock the AFV parameters effectively disabling the learn mode. (The AFV params also allow you to move the maps globally rich or lean).
3. O2 sensor diagnostics (so you can run w/o the O2 sensor)

The "programmable factory racing ECM" is literally a programmable version of our stock & race ECM's and comes with the software to program it. Although there may be some things in the Kimball software that may have been stripped out for us racers (speculation), it looks pretty complete to me.

I'm looking at the Kimball software right now, and for one there is an "Engine temperature correction table"
It is a table with mutiplier values for various engine temperatures.

I don't want to get into any more specifics here, but there are plenty of parameters in the software that deal with engine temperature that are actively used in racing application even if you have the O2 and learning ability disabled
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