Studroes144
TY 4 Stroke God
Had the chance to dyno my sled today and learned quite a bit. Some details on the sled: 2014 viper, 3800 miles, mpi turbo w/ innercooler, .092" head shim from Allen Ulmer along with his pc5 pti base map, mpi fuel pump upgrade, 430cc injectors from hurricane Dave and a few different mufflers. Our main purpose of dynoing was to compare exhaust options, we had the original mpi quiet muffler, the mpi loud muffler and a custom 2.5" exhaust that I had made for mine over the summer. We wanted to compare the 3 exhaust with a true comparison. While changing between the different exhausts we made no changes at all in fuel and no changes at all in boost. Also we were extremely rich of the afr, 9.0-9.2, lots of potential in fuel tuning but we didn't do any of that just to keep if all the same. First pull with the mpi quiet muffler it made 184 hp at 8 pounds, next pull was with the mpi loud can, this is where it gets good! 202 hp at 8 pounds so right off the bat we gained 18 hp. Put the 2.5" exhaust on and made 2 pulls both at 211 hp, just so it's clear again, no changes made at all other than swapping mufflers and all runs were done within an hour of each other at 150-160 degree engine temp which is true operating temp. So from the quiet exhaust to the 2.5" we got a 27 hp gain! From there we just started adjusting fuel some and getting it closer to the 10.5-11 mark, we are still a bit rich at 10.2 but the final pull was a solid 10 psi at 228 hp on pump gas. Gotta give 2 shout outs, first to Allen Ulmer, I called Allen this past week to see if he had an mpi loud can that would fit my turbo so we could use it for testing. He was pretty sure he had a used one from a project sled that we could and he was gonna send it out. When the can showed up yesterday it was a shiny new one that was shipped direct from mpi, after a quick email to Allen he responded right back and said didn't have the right size one for my gen 1 turbo so he purchased one from mpi and had it shipped direct to me just so we could try them out and I'll send it back to him. That's a stand up business man right there and I'd like to thank him again for putting him personal money out there to do some simple tests that doesn't profit him at all so thanks again Allen! Also need to thank d&d where all the dyno testing was done. They spent 5 hours on a Saturday just to do these tests so that's very much appreciated! Hope u enjoy the info, I personally was shocked by the results and very pleased with the gains!!
So there really is something to the statement Dave at Hurricane made. Do you think its heat related or AFR related or maybe both? Very nice of Ulmer to do that. D&D rocks. Is nice to see vendors working together. Thanks for sharing you AWESOME results. Man it has to be a monster!
STAIN
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Are you referring to the HP numbers Dave quoted on an MPI turbo set up in an earlier thread? The one where he thought the MPI quiet can was robbing horsepower?
Studroes144
TY 4 Stroke God
I don't doubt daves findings one single bit, regarding the low hp sled he was talking about, several weeks after he posted that I was standing right in front of the owner of that sled or one that had results that matched daves findings completely. I think there's several things that contribute to lower hp, one being the quiet muffler is so quiet, it's nice for that aspect but that alone makes it very restricted. Also it has a very sharp slash cut directly off the turbo which limits flow. The third issue I saw was when measuring with a micrometer, the turbo outlet on mine was 2.2xx", both mpi mufflers only have a 1.95" flange so right off the turbo its restricting the flow before it even gets to the muffler whereas the 2.5" exhaust measured 2.48" so there's no restriction there at all. Now gotta remember mine was a gen 1 turbo, since then if I'm not mistaken the turbo flange has been made a little bigger, but I don't believe there is any change to the muffler pipe size on the gen 2 setups so there is no doubt going to still be flow restrictions on them too. With the 2.5" exhaust at 10 psi the turbo is still very efficient and making just a tad over 9 hp per pound of boost on a decompressed engine, with the other exhausts the efficiency drops off.
STAIN
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- 2022 SIDEWINDER LTX GT
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I am jealous---I wish I could get some play time on a dyno. It sound very educational.
Ride On
Veteran
Wow that's a lot of H.P left on the table! Can't believe the aftermarket world hasn't been all over this yet... personally do not prefer the noise for my riding.. But.....28hp... Hmmmm
Studroes144
TY 4 Stroke God
I'm with you! I love my quiet muffler, but 27 hp difference is just too hard of a pill for me to swallow. On the plus side tho I must say the open style exhausts are no where near as loud on the turbos as they are an n/a sled and for myself on the trails where I know there's public buildings I'm never trying to draw attention to myself so I'm gonna go with it. Let's hope an exhaust on the new sidewinder has the same effect as it did on the turbo viper but that's an awesome gain!
I have been running the MPI race can for 3 yrs now and cannot get enough of that sound. I have been ...... talked to by the police and DNR on several occasions now and never once was the sound of my sled an issue.... the speed of it on the other hand WAS! When I first put it on after running the stock Stage I MPI muffler the difference was unbelievable.
Studroes144
TY 4 Stroke God
Yup, 18 hp unbelievable to be exact lol. I've been told at 7 psi or less there's not much difference, but seriously who runs less than 7 psi anymore? Lol
