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Discussion Starter · #1 ·
Hoping Dave Weaver or some of you dynno wizards can help me here.

There is a dyno right up the road from me and I want to get a stock baseline on my car before I do any mods. The guy told me it was $84 for two passes. Is that enough to establish a good baseline, and how does that price compare?

He also said a little "bung" would have to be welded into my exhaust to read the a/f. Is he full of shit on that one?
 

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simms said:
Hoping Dave Weaver or some of you dynno wizards can help me here.

There is a dyno right up the road from me and I want to get a stock baseline on my car before I do any mods. The guy told me it was $84 for two passes. Is that enough to establish a good baseline, and how does that price compare?

He also said a little "bung" would have to be welded into my exhaust to read the a/f. Is he full of shit on that one?
Uhhh - that 'bung' thing sounds like bullshit to me. They should be able to monitor exhaust w/out welding. Also, 84$ for 2 passes sounds kinda pricey too - you should get 3 for that.
(that's what's nice about a dyno day, you get more for your $$)

Also, re: the baseline - usually cars respond very differently depending on how much time is taken between runs. 2 passes might give you very very different figures. Personally, I would do at least 3 or 4 properly spaced runs to really give yourself a nice spectrum of #'s to look at and analyze.

Hope this helps, I'm sure others more experienced will chime in.

Clint
 

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I pay $100 for 3 runs. A/F can be measured at the pipes at the back of the car - its probably more accurate in front of the cats but nobody goes to all that trouble.
 

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The bung is so that the air-fuel ratio can be monitored by using a wide band oxygen sensor. The wide band oxygen sensor will be installed in the threaded bung that they weld in the exhaust system. After the dyno, they will install a threaded plug in the bung.

Dynojet has a probe that can be inserted in the end of the exhaust that measures the air-fuel ratio. There are different opinions on the accuracy of measuring at the end of the exhaust pipe. If the car has convertors, then the tail pipe probe would be downstream of the convertors where the welded-in bung would be upstream.

Considering the installation of the bung, that price sounds reasonable. Typical rates I have seem for dyno's is $50-$75 for two pulls without air-fuel monitoring.

It's hard to say whether or not a single trip to the dyno is sufficient for a baseline. Dyno numbers can change depending on the ambient conditions. The software calculates a correction factor, but other issues can change the numbers.

Whatever you end up doing, try to do the same thing everytime you dyno so that you can get the best comparisons. Some variables to try to watch may be same tire pressure, same tension on the tie-down straps, similar engine coolant & oil temperatures, similar transmission and rear end temperatures, etc...
 

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John is right on in my opinion. Also, add tire pressure to his last paragraph, set it at 35 when on the dyno. I charge $65 for 2 runs with air fuel, but you are in a different part of the world so that price may not be too far fetched. Do a cool run, 160 degrees or so and then do a run at normal operating temperature, then repeat. Your baseline runs should be within a few horsepower of each other when the runs are done under the same conditions. The baseline is just that, the best number you can make that is repeatable. If you get 420 on 2 runs and 431 on another, in my opinion, 420 is your baseline. Repeatability is what I look for. :twocents: Good luck, DW
 

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Discussion Starter · #7 ·
Thanks everyone. Sounds like the bung is not that bad of an idea then. I just don't feel comfortable with only 2 runs. Maybe the guy will cut me a deal if I go with...say four.

If they want to go the bung route, do you all feel that is better than the probe? I will be running cats.
 

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Simms:

have him put his wideband into the forward factory well. I have close to 100 pulls using the oem well. My car is a 97, some of the newer cars may show "Service Engine Code", but, not the 96-98. The tailpipe probe is not accurate especially with cats.
 

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Discussion Starter · #9 ·
Jack B said:
Simms:

have him put his wideband into the forward factory well. I have close to 100 pulls using the oem well. My car is a 97, some of the newer cars may show "Service Engine Code", but, not the 96-98. The tailpipe probe is not accurate especially with cats.
Thanks Jack B. :thumb:
 

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Let us know when you take that sweetheart of a car to the dyno and post those #'s.

The car ran well for me so I bet the #'s will be strong.
 

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Discussion Starter · #11 ·
Toby said:
Let us know when you take that sweetheart of a car to the dyno and post those #'s.

The car ran well for me so I bet the #'s will be strong.
Will do. I may hold off till spring now since the car is tucked in for the winter.
 
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