04-17-2013, 01:11 PM #1
VTech Tune - What is Max RPM for stock fuel system
With summer here already in Florida I've lost almost 300rpm due to the increase in water and air temperature. In efforts to save a few bucks I was toying with the idea of putting the stock prop back on to bring the RPM back up. I'm guessing my RPM will be in the 8600 range with my current mods on a stock prop.
I was going to try the 48 8650 169 36 38 AGR 101 tune.
Would this be safe? I have the SuperTech Valve Spring & Retainer upgrade so I know the valvetrain can support the RPM... but what about the stock fuel system? I do not have an AFR gauge. Does the stock fuel system have enough fuel to support ~8600rpm with the stock X-Charger?
Anything else I should consider?
04-17-2013, 02:17 PM #2
you shoukd be fine fuel wise with the stock 48's and x charger, but you need a wideband to be sure a/f is in line
04-17-2013, 02:54 PM #3
04-17-2013, 04:14 PM #4
04-17-2013, 05:20 PM #5
Before you do anything.... I would highly recommend two things.
1. Adjustable fuel pressure regulator
2. a/f gauge
04-17-2013, 06:30 PM #6
I've done this setup 3 times now and 2 of them I've checked on AFR after and found both to be low 12's on WOT.
But this setup is on the limit of injectors with sometimes an overrun of 100% DC.
Bite the bullet and get some VT11's, fuel pump and AFR setup (Even if its cheap and temporary).
04-17-2013, 07:31 PM #7
04-17-2013, 09:48 PM #8
12.9 AFR = 12.9 parts air to 1 part fuel mix = LEAN (very hot)
11.8 AFR = 11.8 parts air to 1 part fuel mix = GOOD
10.5 AFR = 10.5 parts air to 1 part fuel mix = RICH (too much fuel)
The above is only for you to understand what the AFR is all about and is typical for our forced air (supercharged/turbo) applications and will vary with different RPMs (WOT), boost ranges (some have extremely high boost and RPM ranges requireing even more fuel at WOT).
04-18-2013, 06:21 AM #9
Perfect. Thank you. I don't want to hijack this discussion here but I'm ready to do a Vtech upgrade to a stock ski. I heard about possibly needing to do a fuel regulator and sensor and want to understand more.
04-18-2013, 06:52 AM #10
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