• We are no longer supporting TapaTalk as a mobile app for our sites. The TapaTalk App has many issues with speed on our server as well as security holes that leave us vulnerable to attacks and spammers.

AFR too high; how much more fuel pressure is needed?


kinger said:
After playing around with my Motec now in the apex, I realize how blind I was running the PEFI tune in my sidewinder. You know my thoughts on them. If I am going to play with the Winder again it will have a PnP Motec on it. These flashes are just chances as so many things are different from sled to sled and even day to day.

@Turboflash I would keep cranking the PSI up, no harm unless it gets so high it wont idle but it sounds like you are a long ways off from that.
Click to expand...


The Hurricane GAP flashes are not hit or miss. They are really dialed. Since getting the Det protection activated, Hurricane has not lost an engine that I'm aware of. Hurricane Dave refuses to lower the sensitivity of it and it works just as it should, something that can't be said of all the tuners. Some may turn the sensitivity down a smidge so the dash doesn't flash all the time, some Det protections do not work very well at all. Some of us know of the engines failing with other tunes, some don't. Some people talk of them, some don't, its weird why they don't, but you can't force them to talk. And there are those that just get greedy and know they are pushing the envelope, and some shouldn't own a boosted sled at all with and knowledge of boost and inexperience in the arena. Things can go bad fast with big boost, and without proper logging or instrumentation, thus the reason to have a properly working and sensitive, proven detonation protection package.

I have an friend with the Motec on one of his 998's and he pulled his hair out early on in the process blowing it up more than a few times, and he's a good well known tuner and racer. I fact, I have three friends running the motecs on their sleds, and all have down numerous engines now that I think of it, at least 6 blown engines between the three of them in fact, but they also run the Hurricane bundles on their trail sleds now with huge success and zero problems. So I don't think the Motec is the be all end all, you have to be able to grasp and tune the Motec correctly as well, and as you know they are not cheap by any means. So the learning curve is very high with boosted engines. It pays to go with a proven tuner that done it before.
 
Question pertaining to guys like me that do not want multiple tunes, the need of AFR gauges or the use of Octane boosters. Just a sledder that wants as much hp, pull and speed for my type of trail riding as can be attainable!

At what point would you say that the AFR and Octane Boosters are needed with a TD or Hurricane tune?
I mean the TD EcoTrail or Hurricanes 225 are very mild, so those would not need anything but gas and go,and maybe some slight clutch mods.

I was thinking that my new upgrade Tune, which is, (TD MS 17 with their 2.5” SQ muffler, 3 bar and BOV) would be as much as one should go without the addition of AFR or Octane Boosters, but from the sounds of remarks, I best keep some Booster with me Incase.

And if this is a safe tune without those two, will my set up pull timing without a knock light showing if Octane is under
the recommended 91?

Yes I do realize that this is one of those Million $ questions
 
So what I did this year was this... I went from the Hurricane 240SS SM tunes, Dalton weights, 3 bar map sensor (last season) to Hurricane 240/270/300SS , Trail Muffler Tunes, BOV, 3bar map sensor and added more weight to the primary using Dalton weights. Default is set on 270. One day, I went and ran alot of 1000ft runs on old (91) gas. So for that day, no knock light and running 17lbs of boost and 0 degrees celcius, so a warm day. Not enough snow to trail ride yet. Hopefully soon, but from what I am seeing as long as you have 91, you are good. You may get some bad gas and cause a light, but back out of it and cruise until you get some better gas and that is really when you are running 270PM.
 
Without datalogging the snowmobile with the gas you typically use there is no way to know how the Engine is responding to the fuel quality. Just because you do not see the knock light does not mean the sled is constantly pulling timing when doing hard pulls. The ECU will adjust timing to a point without you knowing anything is going on, when it reaches a predetermined number of degrees Of pulled timing it will activate the knock light. You may possibly be pulling timing every time you put the flipper to the bar for more than a few hundred feet or you may not be pulling any, there is no way for you to know without viewing it on your phone with live data or data logging. Tunes that make over 17 psi typically need good quality fuel to do a hard long pull. At that boost level intake temps rise quickly which leads to knock. Corner to corner Riding with short full throttle pulls aren’t too fussy on fuel quality. My personal opinion is that it’s always a good idea to have some octane booster with you and because you do not know if the station you’re going to gas up at is out of 91 or how good the fuel quality is in general, of course you can always just take it easy on the flipper and not worry too much but a little bit of octane boost can help you to keep hammer down and prevent any issues. Fuel requirements will be different for everybody, gearing and clutching combos and different rider weights all affect the load on the snowmobile And just these little things can make a difference
 
I have been data logging this year and I am seeing about .5 timing removed on 270 tune and close to 1 degree removed on 300 tune. This is with fresh 91 octane gas and 3oz boostane. IAT goes up to ~80 before the run is over. It climbs quick so a better intercooler would be helpful for sure. I'm going to add boostane and run again, but haven't had the chance yet. I have a dragy coming tomorrow so hoping to do some runs this weekend. No knock light at those levels of timing removed - FYI (Hurricane tunes)
 
Good info from you Data logging guys for sure.
Looks like I shall do a couple of things that I did not do with my lesser MS16 tune.

Shall fill up with 93 at my local Sunoco before trailering North, and shall keep a bottle of Boostane with me for those times when I do not want any timing pulled, even though I may not see a knock light.

Really appreciate the heads up from all, about how and why timing gets pulled even before the knock light activates!
 
Riding now and next few 4 days - will post final answer but right now the short answer is 'yes'. Looks like for this tune, this D&D Tech2 muffler, it takes about 52 psi fuel pressure to keep safe AFR at WOT!! PEFI muffler must be extremely restrictive! "Derby chip" muffler. Like KA posted, they should (but Sebastien won't cuz all his stuff is 'perfect' - just ask him) warn customers that if they don't run the PEFI muffler, the tune could be extremely lean to the point of causing engine damage. Huge change from 43.5 to 52 psi!!
 
Turboflash said:
Riding now and next few 4 days - will post final answer but right now the short answer is 'yes'. Looks like for this tune, this D&D Tech2 muffler, it takes about 52 psi fuel pressure to keep safe AFR at WOT!! PEFI muffler must be extremely restrictive! "Derby chip" muffler. Like KA posted, they should (but Sebastien won't cuz all his stuff is 'perfect' - just ask him) warn customers that if they don't run the PEFI muffler, the tune could be extremely lean to the point of causing engine damage. Huge change from 43.5 to 52 psi!!
Click to expand...
Awsome tb happy you got er figures out!!
Thanks for sharing all your info very interesting
 
Turboflash said:
Riding now and next few 4 days - will post final answer but right now the short answer is 'yes'. Looks like for this tune, this D&D Tech2 muffler, it takes about 52 psi fuel pressure to keep safe AFR at WOT!! PEFI muffler must be extremely restrictive! "Derby chip" muffler. Like KA posted, they should (but Sebastien won't cuz all his stuff is 'perfect' - just ask him) warn customers that if they don't run the PEFI muffler, the tune could be extremely lean to the point of causing engine damage. Huge change from 43.5 to 52 psi!!
Click to expand...
Any negatives to jacking fp to 52? Idle, midrange, fuel fill-ups, etc?
 
Turboflash said:
Riding now and next few 4 days - will post final answer but right now the short answer is 'yes'. Looks like for this tune, this D&D Tech2 muffler, it takes about 52 psi fuel pressure to keep safe AFR at WOT!! PEFI muffler must be extremely restrictive! "Derby chip" muffler. Like KA posted, they should (but Sebastien won't cuz all his stuff is 'perfect' - just ask him) warn customers that if they don't run the PEFI muffler, the tune could be extremely lean to the point of causing engine damage. Huge change from 43.5 to 52 psi!!
Click to expand...

I figured you'd be up there around 54 or so lbs. Bet the idle is a bit rich with really rich midrange and crusing...
 
BTW - 92 octane w ethanol & Boostane to 95 octane.
Thirstier for sure but nice to see safe AFR finally.
HP might even be up a bit- seems like might need a tad more helix or little more clutch weight. We'll see.
 
Turboflash said:
Hot idle about 11.4 (was 14.1).
Midrange good at 12.5 to 12.7.
Wot so far at about 11.8 to 12.
Click to expand...


Still makes no sense to me that it can possibly be that lean on that muffler, and needing that much fuel pressure. Something seems off in the tune to me. Hillbilly had the different D&D 2.5" muffler on that 280 tune at Dynotech when he was there as I remember, and no way it was as lean as you're seeing here. IMO the added fuel pressure is a band aid for a corrupt tune.
 
You must log in or register to reply here.


Back
Top