Thanks. Need to buy some real soon.

Well, no dice again. Dyno owner invited me out again for a redo.

This time, it read 730ft/lbs in 2 back to back runs. I said, "I think that's a little optimistic"! HEHE. As much I wish it was, that would be nuts.

Next two runs showed in the 360 range after he clicked on something. Uh, WTH is going on?! After reviewing, I noticed the MPH he is showing stops at ~95 MPH while I do mid-130's in 4th.

If I factor the difference between ~95 and ~135, and multiply by the 368 number, that puts me in the low-500 range.

Am I on the right path, or totally off?

I'm going elsewhere after this!

You sure you aren't getting wheel spin? A DynoJet is inertia based and it is quite possible to get erratic readings with wheel spin. I have had this problem trying to dyno Cup cars and the only solution was to strap them down to the dyno, not just fore and aft. They could rev out faster then they had grip to spin the roller. The hub based DynoPack dynos seem to be popular with the turbo tuner crowd as they eliminate the possibility of tire slip.

If your torque curve were linear, and those numbers were accurate, you could extrapolate out to that but I suspect that it tapers off at some point or at least stops increasing and with all the issues you have been having with this dyno, I wouldn't put much faith in the number.

Hello Evan, the first time I thought it was wheel spin, but then I thought no way being rear engined. Also, the roller sounds like it's zinging along if you watch the video.

What do you say about the MPH being off??

I do have one-wheel-peel, and that makes sense since it only read ~95MPH at redline when I do closer to mid-130's? No?

Jerry Aikman operates a dynapack dyno in Cedar Park down the road from you...

aikmanperformance.com

Awesome! Happen to know costs?

Another question.

When I asked for the run to be in MPH instead of RPM (in case ignition was issue), the final MPH was listed as 90-95MPH.

It'll do 130+ in 4th, the gear it was ran in.

Does that indicate wheel spin????

You are getting wheelspin in that video.

You think? I thought so?

Having spent more time then I care to remember around dynos it certainly sounds like it to me. Those mobile dynos are notoriously tricky, I would re-test somewhere with a proper in-ground unit at the very least.

Just my opinion.

Thank you for confirming. The 1st thing I yelled out across was I thought it spun. No way I can spin a roller up that fast!

Ignition crossfire will freak out a Dynojet.

Yeah, mine showed dots like a scatter/histogram, leading me to believe ignition breakup.

But, the 90-95MPH was another thing I felt lent to wheelspin.

It may not be a dyno queen but damn that thing sounds good.

Thanks!

We have ignition pickup issues with our dynojet at times. Some times just flip the pickup on the wire takes care of it. I have switched to a optical and its rock steady. I rarely have a issues with tire slip but it did sound like tire slip in your video.

You got victimized by a bad strap down job - That thing spun hard. The rear axle centerline needs to be a couple inches in FRONT of the dyno roller centerline so that when it loads up hard it is actually pulling the tires into the roller harder. What I saw in that vid was just the opposite.

You can easily see a wheelspin issue by plotting roller speed (MPH) vs RPM. With no spin or slip this will be a straight line.

Thanks for your input.

Thanks. I notified of dyno owner when I originally asked the question, and he said he now ties down straight instead of the way he did it there.

Didn't know about where the tire is supposed to be either.

We kind of vowed not to use this guy anymore. Friend had issues too.