Using Cold Advace Solenoid for advance at WOT.

[dunsbr]

Hi Guys,
I've been doing a little thinking about the 6.2 in the Humvee and thought I'd bounce an idea off the forum.
The 6.2 in the Humvee has a micro switch mounted on the IP to detect Wide Open Throttle (WOT) to disengage the fan clutch during overtaking etc..
I was wondering if I spliced the wire on the output of this microswitch and used the signal as as a control on a relay, I might then be able to energise the cold advance solenoid on the IP to give me some IP advance at WOT.

Theoretically, this means a bit more grunt when you need it but retains standard timing for cruise and low throttle activities.

Am I thinking right or am I barking up the wrong tree?

Cheers

Brad

[ 11-03-2004, 02:30 PM: Message edited by: dunsbr ]

[More Power]

More timing advance helps to reduce white smoke during a cold start, and more advance can affect power. However, too much timing advance can negatively affect head gaskets.

The book says the mechanically injected 6.2/6.5 should be timed at 3-1/2 degrees before top dead center at 700-rpm and with the engine at or near operating temperature. This is when using a Stanadyne Time-Trac timing meter.

In a dyno test performed a few years ago, it was determined that up to about 6 degrees advance, there was a slight power increase with increasing timing advance. Above 6, and power began to decrease, along with an onjectionable increase in engine and combustion noise.

I'd be a little concerned about the 6 degrees mentioned above for head gasket longevity. Four to four and a half maybe....

MP

[britannic]

In addition to MP's comments, your diesel has dynamic load and rpm timing advance built into the pump - my military manual calls for 4* BTDC @ 1400rpm for the NA 6.2L; I found 2.6* BTDC @ 1400rpm to be optimum for my turboed milspec 6.2L. Using the HPCA when the engine is hot, could lead to damage, overheating and at the least, increased black smoke.

[dunsbr]

Thanks for the feed back guys.

I won't pursue that line of approach then!

It did seem a little to good to be true smile.gif

Cheers

Brad

BTW, How much does the HPCA advance the IP during cold starts?