So to be clear i'm not asking about the timing difference in the pump..

 

@Mopar1973Man, with all of the experimenting and tuning you have done, what would the raised compression in an HO motor do to the timing with the quadzilla? I think people can forget that the motors aren't just a pump difference. It's also pistons, injectors, and compression ratio. With the HO motor being 17:1 versus the SO's 16.3:1, would this make a difference enough to have to adjust the timing?

 

Side note: does quad allow half steps/part of a percent in the canbus sliders? my truck lurches a bit when I go from +1 to +2 in the percentages..

15 hours ago, Silverwolf2691 said:

does quad allow half steps/part of a percent in the canbus sliders?

I went to 27 decimal places to see, but of course have no idea if it would actually act on that or just round off to nearest integer.

Yes the actual fractional value is use. The display when you look after editing will be round up. But when you go back to edit its still storing the fractional amount so that is what it does use for the values. 

I totally agree with Silverwolf on HO motors. I have a 2001 manual HO 245 hp in my 2000 auto & this could be why timing is a little difference with the Hot Rod pump. The more compression the more timing you will have. Never did get a real answer on from anybody on this forum about it. 

5 hours ago, jag said:

The more compression the more timing you will have.

Not really... Like I've mention once in the past post as you add boost pressure and figure the cylinder pressures could be as high as 1,100 PSI. Compression isn't going to make any huge difference, consider the engine alone create 400 to 450 on a compression test. Then add 30 PSI of boost on top and reach 1,100 PSI roughly. There will be enough temperature to light off even low cetane. But what compression does effect is the flywheel torque value. Lower compression engines can run more boost pressure safely vs. high compression engine. Consider the early Ford IDI was 21:1 compression ratio, with no turbo.

Edited December 29, 20213 yr by Mopar1973Man

https://www.motortrend.com/reviews/1101dp-black-sheep-6-4l-cummins-powered-anomaly/

 

21:1 compression and 80 psi of boost. 890hp and 1700ft/lbs on fuel only..

 

On the decompressed pulling trucks, they are running 13-15:1 compression but with 110-150+ psi of boost. They are also running 40+ degrees for timing, because that's where the power is and that's the lead time needed to inject the volume of fuel and have it light off properly. 

 

Lowered compression isnt just for boost.. Air you can compress quite a bit (read as going supercritical, existing as a gas and liquid at the same time) before you have problems, fuel not so much. The lowered compression ratio in race rigs is also so that the piston can deal with the shear volume of fuel that these guys are pushing. Sigma pumps I think start at 16mm for plunger diameter. They can flow 1,600cc of fuel. Factory 12mm p-pumps flow about 125cc. Warmed over 12mm p-pumps are about 400-500cc's.  What that volume is in reference to, whether rpm or time based, I don't know. [Figured it out. cubic centimeters per 1000 strokes, per cylinder.]

 

And another thing, if for a given known volume, if you can compress the air faster, resulting in a faster temp rise, would that not light off fuel with a known flash point faster than one that is slower in temp rise? 

 

Think of an SCBA bottle and how slow you have to fill those up to keep heat down.. faster filling/compression, higher heat.

 

I think you are arguing the wrong point. Sure, overall, compression adds to the torque, but we aren't arguing that, for timing we are looking for the usable window of how quickly the air is heated to a usable level.. It's more along the same lines of cetane (higher cetane, lower flash point, to an extent). 

 

We aren't talking in tens of degrees either. I think its only a 2 degree retard that is built into the timing map of an HO Cummins vs an SO Cummins.

 

In all of our experimenting with the quad, we have found how much a difference even half a degree of timing makes in our trucks, and now we are talking about a two degree difference with definite changes if pumps are swapped.

 

@jag, I would wager a guess that you found the amount of advance that hot rod pumps have built in. And possibly the factory timing curve..

@jag, do you have a hotrod pump made by someone else (industrial/scheid) and sold by BD or is it their (BD's) special high output pump?

 

Rumor has it most hot rod pumps are built on an HO base with the SO pistons and distributor rotor, then an amount of mechanical advance is added in. How? I don't know. If they are built on an HO pump base then it makes sense why his 1500 band is 16°, because its 5° advanced. Giving his truck technically 5°-35° of timing based on the limitations of the pump. And it has to work on "factory" timing, no cruise or retard because his setup cant handle it. 

 

As far as I remember, the quad uses the factory timing number as the low limit in the 1500 band with the 1500 band being the maximum "unmodified" timing limit. Then set the 2000 max and the quad uses the 1500 setting as its low limit. Repeat for the other bands. If I recall, the factory timing doesn't move very much based on load or boost, just rpm. The quad adds a lot of movement in the timing maps with, for some, 6° or more jumps between cruise advance and the max load/low psi timing retard.. 

Well that just made my day, thank you Silverwolf.

I have read until my eyes have bled, but never would of thought to read something like that. Silverwolf, you remind me of a badger that keeps digging until satisfaction has been granted!

The BD pump I have is the special high output. They even invite you to put a tuner on it. I have been running the guts out of this pump since I bought it 2010. It has never skipped a beat, not even this summer when I ran it out of fuel twice. The A1000 Areomotive pump had enough. It did throw the VP death code both times, & I removed them & haven't looked back.

The way I have my timing set is that every 100 RPM'S it gains another degree of timing. EG. 1800 rpm - 18* of timing, at 2200 rpm, I have 22* timing. I know it sounds like bs, but it works.   

To quote Sherlock of the tv series, "I don't know and I don't like not knowing.." (as long as its something I'm interested in..) 

 

The other thing is I'm doing some reading about how to make magnum v8s in the dodges run better and get better fuel economy. Lots of talk about compression and timing with that. Unfortunately it also boils down to you need to machine the block to get it running right.. Everything is fresh in the mind lol. 

On 12/30/2021 at 6:04 AM, Silverwolf2691 said:

To quote Sherlock of the tv series, "I don't know and I don't like not knowing.." (as long as its something I'm interested in..) 

 

The other thing is I'm doing some reading about how to make magnum v8s in the dodges run better and get better fuel economy. Lots of talk about compression and timing with that. Unfortunately it also boils down to you need to machine the block to get it running right.. Everything is fresh in the mind lol. 

Sounds like an interesting project. What is the machining that is done to the block? You have my attention.

On another note, I was going to set my timing back because last week we had a couple of days at -38 C & with the wind it was -49 C. Then I got to thinking, why? So I left it where it was & all is good. First time to see fuel pressure to come in a lot slower rate with my new fuel pump, diesel must be like crude oil. Weather is back to normal now though. Also I got a 5th gen mini ipad upgrade compared to the 1st gen I had. The Quad sure like this one a lot better. It seems the truck runs a bit different, (yuk yuk) but no more waiting for it to find the Quad.

Long version is, the Magnum and LA blocks have very large tolerancing for the factory machining. So much so that the block is machined with the deck higher on one side vs the other, and/or the block is not square front to back. Because there is so much material left over the pistons end up .010 -.050 in the bore combined with a .054 thick head gasket.

 

There is some thing called quench/squish. It is the measurement between the piston and head surface. When its over .060 i think you lose the benefits of quench. The benefits are that it mixes the air fuel mix better and it forces the flame to burn in the valve area of a wedge head. It also keeps heat out of the rest of the piston and head area that is really close to each other. This lessens the chance for pre ignition.

 

Best quench is .030-.045. People have run tighter, down to .028.. pumping losses start going up after that though. 

 

Best way to get quench is to square the block then deck it down to "zero deck" then use the head gasket to set the quench height. 

 

The hard part is when you get below a certain height, material temperature stretch, clearances of your bearings, and rpm all start coming into play. 

 

Best for tight quench is the factory cast iron rods, hyperutectic (sp?) Pistons and lower rpm (sub 6k).