260 mixture differences port and stbd

[mrcrsr]

just got done having my 260 dynoed, found something interesting, the stbd side of the engine runs richer then the port(reading the piston tops), is this due to the placement of the injectors?

[mrcrsr]

tttttttt

[Markus]

Is there a big difference? - There shouldn't be...

[Way2slow on H2O]

Did you have an EGT to verify temps?

[mrcrsr]

yes, at full power no difference in egts,but very noticeable on the piston tops, port side of the engine had the nickle to dime size wet spots on the pistons, stbd was the size of a quarter to half dollar-almost to the center of the piston

[RBT]

The ECU fires batched pairs, so 1 & 2, 2 & 4, and 5 & 6 fire together. Unless you have offsets in your injectors, and that is very unlikely due to having one bank different than the other. What you are seeing is the volumetric differences in the pumping of the rotating assembly. Turn it to LH and you will likely see the opposite.

[Stitch King]

:iagree:

On my system, I had to calibrate the injectors leaner on 2,4,6 because the egt temps were 50 degrees apart due to VE.

[Way2slow on H2O]

Look at the power we're leaving on the table with the differences!!!

I melted 2 & 4 with 1,3,& 5 wet to the point of going another 2% lean on the potentiometer to bring the temps up, but can't. Temp on Port @ 10,500 = 1325. Temp on stbd @ 10,500 = 1210. These temps were at approx. the 1000'. Spraying nitrous from the 1000' to the 1188' (approx 1.25 seconds @ 100 mph = 147 fps) the port temp elevated well over 1400* while the stbd stayed under 1400* taking out #2 then #4.

I relyed on the rev limiter to dump 40% more fuel at the time of nitrous delivery and I missed my calculation, lol... 11,000 limiter = 40% more fuel = 2 jet sizes smaller on the enrichment = 500 hp @ 12,000 rpm :D Tony Brucato informed me later the ACU limiter was set at 11,000 not the 10,500 I thought.

Ronnie

[mrcrsr]

that's what i find surprising, there is definetely more power to be had, if this is the case why not set up 3 injectors to be leaner then the other 3

[Markus]

that's what i find surprising, there is definetely more power to be had, if this is the case why not set up 3 injectors to be leaner then the other 3

Because there is no easy way to do it with the Merc EFI system or the Brucato PCU which uses the same set-up. The MAD EFI system does support it.

I suppose you could have two fuel rails and regulators and get to it by running lower pressure to one bank...

[RBT]

that's what i find surprising, there is definetely more power to be had, if this is the case why not set up 3 injectors to be leaner then the other 3

Bingo...... and more to the point if we have to run batch fired ECU's, all six injectors SHOULD be different to make all six run the same. Having matched injectors IS NOT ideal.

[YELLOWSS]

it is a simple system that has room for improvement!!!!!!!!!!!!!!!!!!!

[RBT]

it is a simple system that has room for improvement!!!!!!!!!!!!!!!!!!!

it is a simple system that is very misunderstood.

[Way2slow on H2O]

that's what i find surprising, there is definetely more power to be had, if this is the case why not set up 3 injectors to be leaner then the other 3

How long would the injectors stay in that state as when installed? I've noticed out of every set I send to Brucato there's at least 1 that is too lean, and in some cases three (at least 1 was on the port side and took out a piston, lol). Were they lean from the factory or went lean over time?

If we were to try 3 lean injectors, what would the starting point be? I know there's a margin of flow for injectors, but what would a base line be percentage wise?

Ronnie

[mrcrsr]

it would have to be trial and error, naturally starting small, or if we guess that 3 percent of adj. on the computer would do the job, why not take 3 percent out of the flow of the inj. as a starting point?

[RBT]

If you have enough injectors that will work. Mine are labeled how many cc's they flow... and are used accordingly.

[STV_Keith]

Next problem...I have found that the lower cylinders make more HP than the upper cylinders. How you gonna deal with that? :D

[Markus]

Next problem...I have found that the lower cylinders make more HP than the upper cylinders. How you gonna deal with that? :D

Simple. Do like Yamaha: Reduce compression on the lower cylinders by using larger combustion chambers.

[mrcrsr]

ekes!! another proverbial wrench thrown in the works!!! but one thing, if that was the case i would have seen a difference in the piston on 5 and i didn't, the whole banks were identical

[stvhelm]

if you have the heads off then determine which cylinder is rich and swap it with the the injector from the leaner cylinder. this works very well unless your stuff is real messed up. its also possible one of your switch boxes is weak and is not firing all cylinders 100%. that would leave one bank rich looking

[RBT]

Next problem...I have found that the lower cylinders make more HP than the upper cylinders. How you gonna deal with that? :D

That is easy,
like I mentioned before, 1 &2 are together, 3&4, 5&6... the ECU, Merc or Brucato have offsets. You can add more fuel to 3&4, and again more to 5&6.
My merc has 6 EGT probes..

RT

[STV_Keith]

That is easy,
like I mentioned before, 1 &2 are together, 3&4, 5&6... the ECU, Merc or Brucato have offsets. You can add more fuel to 3&4, and again more to 5&6.
My merc has 6 EGT probes..
RT

So have you found the same thing then?

[RBT]

ya, I thought it was common knowledge, the passing exhaust scavenges the lower cylinders.

[mrcrsr]

the switchbox is a possibility, injectors were just done

[YELLOWSS]

brucato, usually will number your injectors, for which cylinder to install them in!!!!!!
even new ones... he also will send new injectors back if they don't meet his requirements!!!!

roy