Thread: X Ski Air/fuel Ratio
10-22-2009, 07:33 PM #1
X Ski Air/fuel Ratio
Ok need some info I have been running my T-X with a B-Kit and 50`s and my air/fuel was around 11 at WOT a little to rich
Then I needed to do some maintance on the B-Kit so I just put the stock SC and injectors back on my other mods are 4" air, riva Thru hull exhaust, filter removed from manifold, and intercooler relo kit and my air /fuel is now 12.9-13.1 I dont know what a stock X ski ratio is but I really dont have any mods that would make a big difference in the air/fuel from stock the air temps were in the upper 60`s
what do you guys think and what does a stock x ski numbers look like
10-22-2009, 07:36 PM #2
10-23-2009, 07:24 AM #3
I have always felt that the X skis are on the limit with stock 42s I mean if you put an x charger and intercooler on the rxp you need 72psi of fuel not to be lean?? I know the ecu is mapped different and the fuel pump has more voltage but how much can those 2 things make up for.
I cant say that Im suprised by the leaness due to the 4 inch, exhaust and mani upgrade, that allone will have got 1.5-2psi and the engine will be breathing much better + your air is fairly cool.
How many rpm did you drop from removing the B Kit?? maybe this has something to do with it although I would have thought with lower rpm you would run richer. R88
10-23-2009, 07:28 AM #4
I dont remeber what they were with the B Kit on it, but when I rode it the other day it was turning 8040-8060,AFR 13.0 at 74.3 mph.......
10-23-2009, 07:51 AM #5How many rpm did you drop from removing the B Kit?? maybe this has something to do with it although I would have thought with lower rpm you would run richer. R88
10-23-2009, 09:21 AM #6
10-23-2009, 09:24 AM #7
Guys Two question just to see differences in my set ups.
What is your FPR set at with
X SCer, 42's and a External IC on a RXP?
Also on a X boat what does the ski act like with a B-kit and 50lb injecters?
Is this really all you added is 50's with your B-kit?
10-23-2009, 10:25 AM #8
Here you go!
THe AFR recordings are on T-X stock ecu and power, with 4 inch custom air, riva relocation kit and manifold filter removed, with thru hull exhaust.
70 air, 77 water, 29.8 pressure, 59 dew, 2,200 ft = 3,800 ft RAD
added 84 ring and saw exact same speeds, no change, 10.0 psi boost at 8,060 with flashes of 8,080 rpm.
So was better RAD and going from 85 to 84 same rpm with same speed.
72.5 to 73.5 mph. I did notice that the prop almost wants to come on hooked with this ring, not sure tho, as i tried to repeat and it hooked good. It felt faster top end but GPS says no.
my mods for any that want to know when looking at AFR:
4 inch front air without filter, no filter in manifold, relocated X ic, j pipe with gibson. stock ecu and X sc.
AFR readings ( 2 different recordings)
warmed up ski good, then 1st recordings:
idle - 12.9-13.1
2,500 rpm - 12.1
3,000 rpm - 11.9
3,500 rpm - 12.0
4,000 rpm - 12.5
4,500 rpm - 12.8
5,000 rpm - 13.2
5,500 rpm - 12.9
6,000 rpm - 13.1
6,500 rpm - 12.5
7,000 rpm - 12.4
7,500 rpm - 12.1
8,000 rpm - 11.7
8,060 rpm - 11.5
After that recording i made some speed runs for a good while and noticed that it was starting to lean out more with some high 13,s to even low 14,s when cruising say 60 mph.
So i let the ski cool down a bit ( 5 minutes) and did another recording.
idle - 13.3
2,500 rpm - ?
3,000 rpm - 12.5
3,500 rpm - 12.7
4,000 rpm - 13.1
4,500 rpm - 13.6
5,000 rpm - 14.1
5,500 rpm - 13.8
6,000 rpm - 13.8
6,500 rpm - 13.1
7,000 rpm - 13.1
7,500 rpm - 12.9
8,000 rpm - 12.6
8,060 rpm - 12.4
I am pretty sure that the sensor was not messing up as after riding it still was calibrated correct.
added shorty gibson,
Ski ran same rpm 8,100 dead on the money. I could not tell much difference in acceleration with mufler to without. Ski did idle better and It ran really good.
It guietend the exhaust down at idle in wake and up to 4,500 rpm. But above 5,000 rpm it seems to be almost as loud but sounds better.
Definetly has better tone with muffler.
Boost was 11.9
I accidently filled fuel tank up full so only got it down to half.
with full tank was running 77.5 to 78.0. At half tank last pass was 78.9 mph.
Ski is running good i just need to overhaul the drive and install setback pump.
There is so much power i can break the prop loose anywhere below 5,000 rpm with my worn carbon wear and perfect prop and new wear ring.
Here some pics from today and my RXP engine compartment that i no all too well .
10-23-2009, 10:46 AM #9
10-23-2009, 11:03 AM #10
11.5-7 afr at 73psi. Im a little rich on top I know, I will be adjusting for 12 this weekend. R88
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