519hp and then 118hp the second run??? Inertia Dyno Operation

BiodieselPower

BiodieselPower

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Oct 7, 2009
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So I had never been on a dyno before and the operator was absolutely no help in telling me what to do. It was at a car show and I was the only diesel to run. Operator claimed he had dynoed lots of diesels before and had one hit 1900hp. I ran four times and three were below 200, with one 519. It should have been closer to 700. The run with the most HP I pulled 50psi boost and on the low runs it was 60psi??? And the 519 run was the only printout he gave me, the graph went from 3350rpm to 3550 rpm(max power was at 3350 and it tapered off from there). my truck seems to pull hardest at 2800RPM and i'm wondering why the printout was only for 200 RPMS. It was a Dynojet 248. Just curious what i did wrong and/or the operator.
 
just a question but if you have never been on a dyno before how do you know that you should have made closer to 700hp?
 
Which he has neither of.... but maybe he has since changed his setup which is why he had hopes of 700hp.
 
It ran a 12.9 with the 63 in the quarter and I am running the s467.7 now with 5x20's instead of ddp stage 4's. Boost is 60 instead of 45 and definitely pulls Waaay harder now compared to friends trucks. I didn't notice anytime slippage in the videos. Trans defiantly wasn't either I drove 900 miles home just fine. The crank pickup was screwed up because he said it would read double. The chart shows the truck running like 6800rpm. Operator said it always does that... he said the last diesel he ran had trouble spooling up so I wonder if he didn't break it very hard or something.
 
I'd never dynoed untill recently either but after reading some, I decided to head up to Angola and run mine on a dynotech dyno.

Its pretty repeatable as in I made two identical setting runs back to back only had a 2hp difference between them. I guess its stingy with the numbers compared to a mustang or dynojet, but I'm more interested in finding out what works and what doesn't for my truck. I'll be heading back up there because I have a few other things I'd like to try.

edit: thats a load cell dyno in angola.. I wouldn't bother messing around with an inertia.
 
Last edited:
ahale2772 said:
chances are the pickup was not reading off the crank 100%
Click to expand...

This was your problem dynoed on a dynojet many times and the rpm pickups are terrible... have him print out hp only numbers off of drum speed numbers will be closer
 
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