Mpi stage 2 questions

[jim rice]

Oh I thought maybe they had a big crop farm a lot of that in their area

 

[Studroes144]

Nope as far as I've ever seen it's snowmobiles 24/7/365..with the occasional motorcycle ride which with this weather we are having it's tempting to get the bikes back out. So back on topic, yes the mechanic that did the install on mine and would be doing the additional work is very knowledgeable with the kits as well as the engines. They did quite a lot of dyno testing on one of the other kits they installed and to his knowledge he thought the stock injectors would keep up with 12 pounds of boost with an upgraded fuel pump. I've also spoken with another guy who has a stage 1 with upgraded fuel pump that says he can run up to 12 pounds with stock injectors. I know I should just go ahead and do the 4th injector, but I don't feel that 10 pounds of boost is pushing the limits of the fuel system as long as I swap out the fuel pump.

 

[jim rice]

So do they run at higher pressure or just more volume?

 

[Studroes144]

Couldn't tell u for sure at this point, only chatted briefly yesterday with the mechanic and he said stock injectors can go up to 12 pounds as long as you have a "bigger" fuel pump. What he means by bigger I'm unsure but they have basically done all of this already on the previous stage 1 kit they did except that one went to lower compression pistons and Carrilo rods

 

[Adams574]

How many pounds would the stock fuel pump be good for? I've read the nytro were running 8lbs for the past few years.

 

[Studroes144]

From what I've gathered I think 8 pounds is about the limit for the viper too with a completely stock fuel system

 

[Yamadog]

Well after a year and blown motor under my belt, I can only tell you what I ran into. 11.5 at WOT is too lean. The stock injectors can not handle 9 lbs of boost and going with oversized is not the answer cause you are way too rich at low and mid throttle . the ECU does not know what injectors you are runnung and cannot adjust fine enough when you are off the throttle. The best setup is a 4th injector in the intercooler and a seperate gems controller for that injector. I am now switched at 9 & 12#'s cause that is the most the MPI stage I turbo can produce. I upgraded to the quick spool waste gate, high flow fuel pump, 4th injector, Low compression pistons and carillo rods. Even at that set up we calculate at low elevation I must run 95 or higher octane at 12#'s and 93 or higher at 9#'s.

I only ran the sled one time for a short period earlier this season at 9#'s cause I did not have the race fuel to get the octane boosted above 95. When Allen Ulmer tuned, clutched and dynoed it we are seeing 10.5 to 10.9 at WOT . Last year at 6#'s I was seeing 11.4 on the AFR on short WOT runs and thats when it blew up.

I am loading up tonight and heading to the UP in the morning (Sunday) for a few days to see how she does.

 

[jim rice]

Well after a year and blown motor under my belt, I can only tell you what I ran into. 11.5 at WOT is too lean. The stock injectors can not handle 9 lbs of boost and going with oversized is not the answer cause you are way too rich at low and mid throttle . the ECU does not know what injectors you are runnung and cannot adjust fine enough when you are off the throttle. The best setup is a 4th injector in the intercooler and a seperate gems controller for that injector. I am now switched at 9 & 12#'s cause that is the most the MPI stage I turbo can produce. I upgraded to the quick spool waste gate, high flow fuel pump, 4th injector, Low compression pistons and carillo rods. Even at that set up we calculate at low elevation I must run 95 or higher octane at 12#'s and 93 or higher at 9#'s.

I only ran the sled one time for a short period earlier this season at 9#'s cause I did not have the race fuel to get the octane boosted above 95. When Allen Ulmer tuned, clutched and dynoed it we are seeing 10.5 to 10.9 at WOT . Last year at 6#'s I was seeing 11.4 on the AFR on short WOT runs and thats when it blew up.

I am loading up tonight and heading to the UP in the morning (Sunday) for a few days to see how she does.

That is the best info I have heard yet , from real life experience what happened when it blew up rods or just head gasket

 

[Studroes144]

I'd be 100% shocked if it blew because of an 11.4 afr. That's not too lean by no means. I could see if you were up above 12 and holding for long stretches. Too many mixed opinions floating around and by asking the dealers, obviously I would need all the extra stuff, they gotta make the sales. Not slamming them in any way, that's just business and how it works. Will hafta just do real world testing and watch it closely

 

[titanrcr]

Well after a year and blown motor under my belt, I can only tell you what I ran into. 11.5 at WOT is too lean. The stock injectors can not handle 9 lbs of boost and going with oversized is not the answer cause you are way too rich at low and mid throttle . the ECU does not know what injectors you are runnung and cannot adjust fine enough when you are off the throttle. The best setup is a 4th injector in the intercooler and a seperate gems controller for that injector. I am now switched at 9 & 12#'s cause that is the most the MPI stage I turbo can produce. I upgraded to the quick spool waste gate, high flow fuel pump, 4th injector, Low compression pistons and carillo rods. Even at that set up we calculate at low elevation I must run 95 or higher octane at 12#'s and 93 or higher at 9#'s.

I only ran the sled one time for a short period earlier this season at 9#'s cause I did not have the race fuel to get the octane boosted above 95. When Allen Ulmer tuned, clutched and dynoed it we are seeing 10.5 to 10.9 at WOT . Last year at 6#'s I was seeing 11.4 on the AFR on short WOT runs and thats when it blew up.

I am loading up tonight and heading to the UP in the morning (Sunday) for a few days to see how she does.

I regards to the ECU not being able to tune fine enough with oversize injectors, the Power Commander does the tuning of the fuel curve not the ECU. The Power Commander has the ability to remove up to 99% of the fuel being supplied by the ECU and add up to 250%. There are a bunch of guys on the site running larger injectors with a PC-V and I haven't seen any reports of running way to rich at low and mid throttle settings? For a guy running 5 or 6 lbs boost with stock injectors and wanting to upgrade to 10 lbs I think the larger injectors are the way to go but that may require ditching the GEM controller in favor of a PC-V.

 

[Studroes144]

I regards to the ECU not being able to tune fine enough with oversize injectors, the Power Commander does the tuning of the fuel curve not the ECU. The Power Commander has the ability to remove up to 99% of the fuel being supplied by the ECU and add up to 250%. There are a bunch of guys on the site running larger injectors with a PC-V and I haven't seen any reports of running way to rich at low and mid throttle settings? For a guy running 5 or 6 lbs boost with stock injectors and wanting to upgrade to 10 lbs I think the larger injectors are the way to go but that may require ditching the GEM controller in favor of a PC-V.

That has crossed my mind, I'm getting more familiar with the gems and I do like the easy adjustments of the gems but just don't think it controls the stock ecu fueling enough to really "fine tune", I can get good safe afr numbers with the gems, just think it can be dialed in a bit more which I know could be done with a PCV

 

[Yamadog]

We have all been through the reasons for blow up over 20 diff. posts. Everybody has an opinion and none of them ever ran this sled (viper) with a turbo!!!! Another sled did the same thing so it was not just me. I am going with what I was told by the most experienced person I know - Allen Ulmer!

When mine blew I was only at 6#'s. It notched the cylinder walls between 2 cylinders which was due to head gaket failure. It ruined 2 pistons, destroyed the block, hurt several valves and notched the head where it burnt between 2 cylinders. My troubles started early when I was only at 4.5#'s of boost dropping cylinders.

You can run oversized injectors but you cannot take fuel away from the minimum settings with a gems controller you can only add to the base fuel map.. The Ecu does not know what injectors you have in it and can only be turned back to the factory stock settings for the small injectors which means they are dumping too much at idle and lower throttle which will cause a bog at launch and hard starting. As far as AFR #'s run what you want but both sleds that blew up were in the mid 11's at wot. The installer in both cases blamed it on the gauges mine was AEM and the other was KOSO. Mine was getting 8 mpg so I know I was dumping A TON OF FUEL. That is in the past now and I trust that what Allen has built for me is right and we are mid 10's (AFR) at WOT at 12#'s of boost on the dyno.

All I know is this thing is so wicked that the AFR means nothing to me, I am under 8 seconds to 100 mph and that was at 9#'s of boost on bad snow and no studs. I havent even pulled the trigger at 12 yet and have just installed 148 studs. But you cannot read anything on the gauges. It leaves so hard all you can do is fight to stay on it and when your eyeballs come back to the front of your head is prepare for braking to get it through a turn.

 

[tator]

there are many hurricane kits (should be all) with larger injectors running perfect. the rough (rich) idle was from the layout of the vacuum line to the stock sensor. by routing the vacuum line back to its original location the rough (rich) idle HAS been fixed with or without the remap. idle at 13 mid 12.5 WOT 10.7 max. think those numbers are pretty good. i have read of a report of bog at launch and it was with a kit that uses stock injectors. I do agree that MPI has a quality product. But i know Dave at hurricane has done testing WITH stock injectors and the PCV. for HIS kit to be the safest for the motor he says to use the larger injectors. I haven't read yet of a hurricane kit being too lean, bogging, or having ENGINE trouble. far as not being able to take fuel away from the minimum settings with the gems controller. Dave DOESN'T use the gems controller. gauges? i run them but many with the hurricane kit do not and still do not have trouble. THE GAUGE WILL NOT MAKE YOUR SLED RUN PROPER. it is a tool to make sure it is set up correct. i dont know why the mpi controller does not come set up at the proper levels. seems to be that improper setup based on GAUGES is the reason for the trouble. do all mpi kits have to have gauges for setup? if not how do you know what to set the gems at? is there a standard? if there is why are people changing it? Glad to hear Allen has your sled set up awesome yamadog sounds to be a beast did Allan build the motor or just tune it with the added boost? Allan has great knowledge of these sleds, boost, clutching, and everything in between.

 

[Yamadog]

TATOR ARE YOU RUNNING OVER 6#'S OF BOOST? Stock kits running 6 or less are fine with the stock injectors.

It is anything over that causing problems with stock fuel pump and injectors. I was fine with small inectors to 8#'s 9 started running lean at WOT.

 

[tator]

no the kit is set at 5-5.5. didnt yours and Tims go at 6lbs or less?

When mine blew I was only at 6#'s. It notched the cylinder walls between 2 cylinders which was due to head gaket failure. It ruined 2 pistons, destroyed the block, hurt several valves and notched the head where it burnt between 2 cylinders. My troubles started early when I was only at 4.5#'s of boost dropping cylinders.