DYNO TEST DISSAPOINTMENT

#1

I took the car last Friday to the dyno (Dynojet 248), and was quite dissapointed.
The max HP was 143, and max Torque 135, but the average after three runs was 142.5 HP, and 133.5 Torque.
I was hoping to get closer to 150 HP and 140 Tq.
What was the average last year at Nationals?
What’s the average this year?
Is it because I’m at 2,100 feet above sea level or what? any imputs?
With those number I barely make it to GTS1, and I’m still able to lose around 200lbs to get closer to the limit and not move to GTS2

#2

Dyno numbers are just about worthless for comparison unless other E30s have been on the same dyno.

#3

mskeen wrote:

Very true. And to really be meaningful, the comparison E30’s need to be dynoed on the same day.

#4

I disagree. A properly setup Dynojet 248 spitting out SAE corrected numbers should be compareable to another Dynojet 248 spitting out SAE numbers. I hope you got the files from the shop so you can look at them yourself in WinPep Dynojet’s software. If you do have them, if you could post them so I could look at them that would be great. With the software you can check the SAE correction parameters they used such as air temp, humidity, and altitude as well. What gear did they dyno with? What gear ratio did the dyno calculate for each run? Did you get air fuel plots? Did they stick the O2 in the exhaust or use a sniffer in the tailpipe?

#5

it shouldn’t be the crap-shoot that you guys are implying. Dynojet 248’s should be consistent if they are maintained and the readings are supposed to be corrected for ambient humidity, temperature and pressure (altitude) per an SAE standard.
cheers,
bruce

#6

leggwork wrote:

[quote]it shouldn’t be the crap-shoot that you guys are implying. Dynojet 248’s should be consistent if they are maintained and the readings are supposed to be corrected for ambient humidity, temperature and pressure (altitude) per an SAE standard.
cheers,
bruce[/quote]

Got some data that can be shared with the racer group that would lead us to believe that the series is moving forward?

Don’t read any thing into the my question about the horsepower values in the Southeast. There was not any display of straightaway talent at our last event. Rather, this is a growing series and it could use some structure before …

Regards, Robert Patton

#7

I’ve had my car on three different dynojets, 2 were 24" and one was 48". Horsepower on all three were less than 4 apart.

Your motor has a classic problem. The head needs to be rebuilt, valves reseated, and the other small things that make horsepower. With that done, motor should make 165ish. Chuck

#8

Victor, you’ll likely end up doing as Chuck suggested.
First, purchase the tools and learn how to do a leakdown test.The ability to work on the car is often overlooked as a valuable and, with trackside repairs, necessary part of this sport/hobby.

Regards, Robert Patton

#9

I’m all for fixing the car myself, just don’t know or didn’t know where to start. But if it needs a new head, a valve job, and whatever else you can suggest, I’ll work on that in the two months prior to the Nationals since I want to get the most out of the stock engine.
What do I need for the leakdown test? How do I rebuild the head, do I send them to any shop?
The dyno test was certified by the technician since I need that for the GTS series, they used SAE Smoothing and Correction Factor 4. I got the files if you want the links, and they used the oxygen sensor and inserted a pipe in the exhaust, three runs at three different gears up to the rev limiter.
This shop does dyno tests all day long every day, they even suggested some tunning, and add-ons but since we can’t do that I saved them for future reference.

#10

Bringing this thread back. I just found out that there is a Dynojet about 45min from me. Are there specific settings that I should tell them to configure such that pulls on their dyno will be more comparable to what other SpecE30 guys are doing?

Are there logical questions that I should ask them? Like “When was it last certified and how?” or whatever.

#11

Just make sure the operator is experienced with the equipment. Then make sure the adjustments for temp/humidity/etc. are made. If your head is relatively fresh, your dyno plot should look like the one I posted. Chuck

#12

SAE corrected numbers, not some BS correction factor the dyno operator puts in so people feel better about their cars.

#13

Ranger wrote:

[quote]Bringing this thread back. I just found out that there is a Dynojet about 45min from me. Are there specific settings that I should tell them to configure such that pulls on their dyno will be more comparable to what other SpecE30 guys are doing?

Are there logical questions that I should ask them? Like “When was it last certified and how?” or whatever.[/quote]

The Showroom Spec Miata rules use the Dynojet 248c at various shops. The specs call for SAE correction factor 1.05 and smoothing factor of 3. The specific SAE correction factor handles temp, humidity, altitude, etc. There will be variation between dynos, but we believed that the variation was minimal enough to be a better solution than not dyno testing.

My belief is that raw dyno numbers are generally comparable when using the same brand & model. When comparing pulls from different manufacturers, the shape of the curve should be the same, but the numbers will differ.

Steve D.

#14

This car is simple to dyno. No computers you have to try and trick or traction control and wheel speed sensors that will get pissed off. Just strap it down, put the inductive hook up on one of your spark plug wires, put a sniffer in the tail pipe (unless you have an extra bung for an O2 sensor), and do a 4th gear pull. Make sure you get the dyno files from the operator on a memory stick and then you can make your own plots with the free Dynojet software.

#15

I know of three shops in my area that each have dynojet’s and they all read about the same. The one that reads a little low has a ambient air temp sensor that is off by 20 degrees F. That would account for the odd SAE correction.