96" with Se255 cams, V&H Straight Shots, Fuelmoto intake, PC3 tuner and DK TTI's.

 

Do you have any idea how they were calibrated? If the drums were solid metal they might be close but they are filled with some sort of cement.. Steve Cole of TTS tuners mentioned that their calibrations procedures sucked.. I would agree.. A little over a year ago I bugged one of the engineers at the Vtwin Expo and his big example was that they compared 2 other dynos to one of their newer and older dynos.. The others read different while their new and old ones read the same.. That seemed to justify that all the dynos dynojet made in between had to be good.. BTW.. Remember Wurktruk? While we were discussing this he walked buy and questioned why his dyno read 10% less than everyone else's..

Don't get me wrong.. DJ make a good dyno. it is consistent and reasonably inexpensive compared to what else is available.. They don't spec dyno to dyno accuracy tho..

Attached dyno runs from 2 different bikes run on 2 dynos.. Each bike was run on 1 dyno within and hour of each other then over to another dyno a couple days later.. Both dynos were DJ250s..

The to bikes happened to make about the same HP on each dyno but the output recorded from the dynos is much different..

HD1 is green / blue

HD2 is blue / red

 

Dang, that chart shows about a 10% difference between the two dynos. Definately have noticed some charts/#s posted that don't make sense and this is probably why. Hard to know who to trust except it seems like if you hang out over at HTT enough you start to get a feel for some of the tuners.

 

So 126hp from a custom Kirby Vee-Twin built 124 is out of reality?
Doesn't sound unbelievable to me. Maybe Kirby is a good builder/porter?
Maybe the heads work well with the cam profile?
Bob

 

Here's a 124ci done by Chris Rivas. Probably another happy dyno?
http://www.chrisrivasvtwin.com/tc124cuin.htm
Bob

 

I've never seen this amount of variation. It's obvious to me there is a mechanical issue with one of the Dj250s OR there is a stack calibration issue.
Easiest way to see of there is really a difference is to plot the graphs UNCORRECTED. That eliminates the stack corrections.
If there is still a huge difference it's got to be in the dyno itself. Bearings dragging, eddy brake causing bind in drum shaft, etc.
If the big difference is within a couple hp/tq then the issue is with the stack and its calibration.
This is why we send both our stacks back to Dynojet annually. Just to try to eliminate variables.
We feel confident when both stacks produce the same results after calibration.
Bob

 

Since dyno jets don't measure brake HP I guess anything is plausible..

 

So only displacement determines HP output?

 

2011 Streetbob
Stock bore 96"
SE MCR heads
S&S 570 cams
Should be right around 10:1 compression
Thunderheader
Zippers Max Flow on SE backplate

92hp/101tq
Was going for bolt together Hippo build on a stock 96"

Was a little disapionted in hp numbers. was hoping for 95+. going back to the dyno in a few months, changing to Sawiki pipe and throttle body bored to 50mm by Dan Vance

Dyno is in STD (disclaimer before everyone start complaining)