16.5 or 18* of timing what would the differance be

 

1.5 degrees









Sorry, I couldn't help myself!!! I have nothing more to add!

 

that is pretty funny, but it is a good question, I would like to know myself.

 

It has been a long time since I messed with a 12v but, since no one else is answering I swing at it a little. People with more experience will chime in and correct me I am sure.

18deg ill be slightly harder to start but, it will warm up faster. Not sure that 18 would all that hard to start though? 18deg will make more power but, probably not that much more with less smoke and cooler egt's.
Typically less timing makes more torque and less horsepower on a dyno but, that is typically because it is less efficient and artificially spools the turbo faster due to more exhaust to drive the turbo.

Between 16.5 and 18 I am not sure the average guy is going to notice too much.

Now, correct me if I am wrong isn't there a vaccum advance on the pump or something? I think you are talking about static, unboosted timing right? As boost rises you should have more than 18deg advance, more like upper 20's I think on the 12v's.

 

the timing is fixed where its at i belive. at 18* you will see it fuel harder at a later rpm than at 16. not sure where that sp66 lights but there isnt much room to play with the 3k gsk and a big single. It does start a bit tougher but not much, but mine is partly due to the 20. over marine gasket lowering the compression ratio. if you dont have studs and o-rings 18 might take out the head gasket. Definatly let the engine warm good before getting on it. imho i noticed a big difference between 15.5 and 18*

 

Hmm, its been a while but, 18degress is not much timing. I know a 24v will run 26deg stock.

 

Finally some info on 24v timing. You wouldn't happen to have a nice little breakdown as to where and how much timing a 24v takes, would you? Idle, cruising, part throttle, WOT, etc? Would've loved to know this when I first did my conversion.

 

Idle = 10-12 deg dependant on lots of things!
WOT = 25-26 deg and everywhere in between. Some of the SO motors run 1-2 deg less

Cruising, varies a lot based on setup but, 12-13 on average

 

Example:

Numbers across the top, RPM (obviously..)
Numbers on the left side are an internal number corresponding to load (fuel).
Numbers in the cells are the timing in degrees. But this map isn't the final word, there is another that adds up to 4 degrees at low boost.

 

I wonder why the big drop in timing when going from the 2208 row to the 2944 row? You would think with more fueling and higher rpms, it would want more timing...

However, this is the stock computer timing right? maybe that's one of the area's where the aftermarket boxes really shine is adding timing up top for more power...

 

18° Timing is pretty harsh for most that aren't pulling or drag racing. You need the correct injection and treatments for that without damage. Studs, O ringed head for starters. With the 12V the internal peak pressures get pretty high when you have that advanced timing and 40-50 psi boost. Higher boosted animals with twins, well you should have your head done anyway.

Where that timing advance shines is in the higher RPM bands. With static timing on the 12V, you set it for application. If you are at 3K and above all the time, then up to 20 + would be OK. But if you are in the normal driving range under 3K, I would think 16-17 would be the maximum. IMO of course..

 

Yes, that is stock. Any 'weirdness' you see in that table is probably for emissions reasons.

I 'smoothed out' mine and added 2* across the whole map, but I haven't been driving it enough to see the fuel economy increase I want...

Jim

 

Do you suppose you could normalize these numbers where 3680 = 100%?

My scanguage reports load in percentage.

As far as the 43.34 @ 0 RPM, do you suppose that might be the hard stop in the VP44?

I can sure hear the timing come on at higher RPM's at low load in my truck.

Jim

 

On a stock '01 HO (which is where that map came from), 100% would be 2208.
But, the engine never gets to 100% of that number, even at full load. The highest that number ever gets is 1708 (this is according to the routines that the Cummins CAN bus tools use - I don't know if the normal scanguage uses a different set of routines to collect data from the ECM. Have you ever seen the scanguage go to 100%?)

Notice how the timing in degrees goes up to 24.87@3500RPM, then drops to 14.34? This is because they didn't extend the map past 2208.

I extended mine to 2294 (just copied the 2208 row) and reconfigured the torque settings to go up to 2294, which lets me hit the vp44's internal fuel limit.

The files I have for the '01 SO are different - the load scale starts at 0 and not 221. Why can't people keep things the same and make life easier for everyone.

 

My ScanGauge goes to at least 99%.

Jim