Warning, -16 late build Viper turbo breakdowns, bad rods.

[Mountaintech]

The sled that we did the testing on was a dealer installed mpi turbo kit.the first dyno pull was 141hp@4.5lbs boost. The owner wasn't real happy so i turned up the boost to 6lbs@158hp. He was still upset and asked me to remove the kit and install the hurricane kit. After some discussion we desided to figure out how to make his mpi kit work.the next step was to remove the exhaust from the turbo. It made 191hp@6lbs boost @12.5afr. After modifying his muffler, adding injectors and a pcv, we had the mpi trail kit making 183hp@6lbs boost@11afr.this is a short discription of a day long process

That must have been an eye opening day in the shop. Very disappointing numbers but it seems like you got it figured out.

 

[Yamadog]

Well the hurricane right up does not state whether this was the new updated muffler or the old one. All exhaust are going to cause restriction but that is a crazy loss of power - I would be pissed if I paid the money for the setup and only gained 12 hp.

 

[kviper]

K viper True, but I have the wiseco piston at 10:1 which are less decompression than the head shim at 8.5:1 he is now stating that the loss was all due to the restriction of the trail muffler. He was getting 191 with no muffler saying that the stock motor gained 10.167 hp per lb of boost but the AFR #"s were not safe to run without additional fueling which is what happened to mine back in 14 on the stock motor.

All of this shows that lb for lb the hp / lb of boost is about the same it, is the restriction of the exhaust after the turbo that is detrimental to the gains.

Still lower compression than stock but as I said all things equal. Also you don't have 57% drive line loss you are 57% efficient, 42/43% loss. A 180hp sled should put 102hp to the track using 57%. This is what has always bothered me about a CVT clutch. Very inefficient !

 

[Yamadog]

Yes 40% loss it is 60% of the crank number, but that loss is a function of the clutching loss, the jackshaft, gearing and the drive shaft and is also a product of the drivers. Mr Sleds track dyno #'s are higher on a similar setup due to drivers he is running vs the stock xtx drivers I have.

But if you have ever worked on auto #'s I know I have drastically different hp at the crank on my 68 dart GTS with 525 crank hp and I forget it has been years but I am only 350ish at the wheels if I remember correctly. But believe me 525 crank hp in a 3000 lb car is nothing like 252 on a 550 sled and now my 14 will be over 300 I just cannot wait to pull the trigger - come on snow!

 

[kviper]

Your Dart should be putting way more than 350 to the rear wheels with 525 crank HP! Are you sure it's not 450? Should only loose 15% if it's an auto, 10% manual. The shop that did my Mustang figured mine at about 435 crank and put just short of 400 to the wheels, that's with a 5 spd. Clutching is the biggest loss on a sled though!

 

[Yamadog]

Its been 7 yrs since it was dyno'ed and I cannot find the sheets. I just got it back last week after a year in the interior shop and it was torn down for 2 prior to that, now its winter so sleds are the main thing for now will look at it again this spring still figuring weather to take out the built 727 auto and go back to the factory 4 speed. At 3 miles to the gallon and $10.00 /gallon its just a bit thirstier than the my XTX that only average 8 mpg last season both run on 110

 

[Byam]

MPI guys whit trail kit DONT worry !!! I have a original MPI trail kit whit no add on!! She was 175/180hp on the dyno as told by MPI....

I dont think those number are honnest and i think its .....

11hp/4.5 psi =2,44 hp per psi !! Come on ! The problem was probably somewhere else than just the pipe....

Am I the only one who think that?

Sorry about that

 

[Yamadog]

And it depends on the gears when I bought it it had 511 gears with a mini spool probably more hp at the wheels than the crank with that set up ! It was so nasty I could not keep the wheels on the ground

 

[kviper]

I don't understand the gear effect. You would think lower ratio would show more power due to torque multiplication but when I ask that question I was told it don't work that way? Any way I suppose we should get this back to topic! Sorry!

 

[cannondale27]

MPI guys whit trail kit DONT worry !!! I have a original MPI trail kit whit no add on!! She was 175/180hp on the dyno as told by MPI....

I dont think those number are honnest and i think its .....

11hp/4.5 psi =2,44 hp per psi !! Come on ! The problem was probably somewhere else than just the pipe....

Am I the only one who think that?

Sorry about that

Was just reading Amsnow they use Dynotech I believe. 177hp for MPI trail setup last year. But that brings to question. Two turbo companies are advising not to do it at 190hp. 13hp difference. Barely feel that. Hope rods don't "feel" it. Talk about a mess. This is it.

 

[Kenzie]

I'm hearing Yamaha is calling back all mpi boost controllers even from 14 an 15 including the 16 just to be sure everyone is the same. Have to wonder are year now all going to be de tuned slightly to ensure no damage can occurs an play it safe so the new 16 are not slower then a 15 by a long shot if they got to keep old boost settings

 

[Yamadog]

I do not believe there were any boost controllers for anything in 14 but probably 15 and 16 even though Matt from MPI already stated it was just the batch for 16 that were programmed in error

 

[Joe ltx-le]

I'm hearing Yamaha is calling back all mpi boost controllers even from 14 an 15 including the 16 just to be sure everyone is the same. Have to wonder are year now all going to be de tuned slightly to ensure no damage can occurs an play it safe so the new 16 are not slower then a 15 by a long shot if they got to keep old boost settings

There's no reason to think that. The waist gate default is 4.5-5. So your not getting lower boost then that. The controller on the trail turbo only gives you another 1.5 psi at high altitude to insure the power stays the same in the thinner air.

 

[Dirtbikekid1998]

I'm hearing Yamaha is calling back all mpi boost controllers even from 14 an 15 including the 16 just to be sure everyone is the same. Have to wonder are year now all going to be de tuned slightly to ensure no damage can occurs an play it safe so the new 16 are not slower then a 15 by a long shot if they got to keep old boost settings

yup my dealership called my dads 2015 stx dx with mpi trail turbo back last week. and it has to wait a couple weeks because they were told there were already out of the new reprogrammed controllers to do a swap out.

 

[Joe ltx-le]

yup my dealership called my dads 2015 stx dx with mpi trail turbo back last week. and it has to wait a couple weeks because they were told there were already out of the new reprogrammed controllers to do a swap out.

You got the maf sensor plugged back in? That way if the snow flys he can still get out.

 

[staggs65]

They can take my 15 boost controller back if they want. It's sitting on the workbench if they want it.