How to Dyno a 4WD V8

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I locked my center diff they told me that it turns off the trac-control and they didnt want it to kick in if the wheels spun and second reason was that the power was equal at the front and rear wheels? It did not hurt anything good luck:D
 
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I would make two passes, one locked, and one not locked. The one with more hp would be the one I would use as the base number. You would need to make sure that when you re-dyno, after mods, you use the same center diff position.

The dyno operator should know which to use. You could also contact Dynojet to get it from the horse's mouth.

Koz
 
Great. Thanks for the input, guys. That is pretty much what I was thinking Koz, making one locked and one unlocked. My main concern is how fast can I go w/ it locked? Also, I knew if I leave it unlocked the traction control will interfere.
 
OK, its official. I'm having the baseline dyno at 11am on friday. I'll report results as soon as I can afterwards.
 
im going with 06 on this one, you should be in the 205 to 215hp (19%-22% drive line loss) depending on atmospheric conditions, diff setting and overal strength of engine.
 
Casper said:
im going with 06 on this one, you should be in the 205 to 215hp (19%-22% drive line loss) depending on atmospheric conditions, diff setting and overal strength of engine.
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I don't know guys...I'm thinking 200+ is optimistic at this point: A) Because the dyno I'm going to use is around 5800 ft. altitude, and B) I think 19%-22% drivetrain loss is optimistic. I was reading somewhere that STi's and Evo's have around 30% losses, and they are viscous coupling difs, where mine will be locked mechanically (= more loss). What do you think?

*EDIT* OK, I just looked up someone else here on the forum who dynoed his non-vvt V8 4x4 and experienced around 19% loss, so maybe it will be 200+, we'll just have to wait and see now won't we... :p

So howcome I read somewhere that STi's and Evo's have 30%?? Are they really that bad? Or was it just bad info?
 
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my 06 at 800 miles dynoed 213 awhp on a awd mustang dyno with the diff locked without it the traction control would cut in and cause erratic sp? readings but that is at almost sea level good luck with the dyno.... I know when I go to tahoe my runner runs alot more slugish than when Im in the valley......
 
Conner,

forgot about that man...at 6000' you have lost approx 30% of power out put due to the pressure altidude even at Standard Pressure and Temp.

Even though you are slightly under 6000' you should expect to see an automatic 30% chop off the SAE rated nubmers. Then take 20% of that for drive line loss.


so really man you should be looking for a number in the 160's....ouch.
 
Casper said:
Conner,

forgot about that man...at 6000' you have lost approx 30% of power out put due to the pressure altidude even at Standard Pressure and Temp.

Even though you are slightly under 6000' you should expect to see an automatic 30% chop off the SAE rated nubmers. Then take 20% of that for drive line loss.


so really man you should be looking for a number in the 160's....ouch.
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Yep, oh well. :happens: :D
 
It looks like the diff needs to be locked. The dyno operator will adjust for altitude. According to my calculations you will loose approx 17% HP @ 1 mile high. There are like 10 different factors that determine the correction factor. Tire air pressure is important; I would pump them up to 40psi. Make sure they use a sniffer to see what the air/fuel looks like.

Koz
 
I'm going to run with it locked for the first two runs and if I get good consistent numbers for those I'll run unlocked for the last one. If I get bad or inconsistent numbers I'll run locked for the 3rd run. I'm going to leave my tires as they are, because a) I don't feel like messing with it, and b) I want to simulate real world conditions as much as possible, so that also means I'll be running mid-grade (87 octane in CO). That is what I'll be running my Unichip on so that way I keep the results the same. I'll be sure to report down the line if premium fuel has an effect on the unichip...

I wonder if they'll give me real power and corrected power, so I could compare the real power w/ someone at sea level and actually see what the loss is. Thanks for the help guys!
 
OUTRNNR said:
I'm going to run with it locked for the first two runs and if I get good consistent numbers for those I'll run unlocked for the last one. If I get bad or inconsistent numbers I'll run locked for the 3rd run. I'm going to leave my tires as they are, because a) I don't feel like messing with it, and b) I want to simulate real world conditions as much as possible, so that also means I'll be running mid-grade (87 octane in CO). That is what I'll be running my Unichip on so that way I keep the results the same. I'll be sure to report down the line if premium fuel has an effect on the unichip...

I wonder if they'll give me real power and corrected power, so I could compare the real power w/ someone at sea level and actually see what the loss is. Thanks for the help guys!
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Conner,

i hope you realize that you cant use mid grade stuff with the unichip. its tuned specificially for 92. Do NOT use midgrade...you might as well use premium.
 
Casper said:
Conner,

i hope you realize that you cant use mid grade stuff with the unichip. its tuned specificially for 92. Do NOT use midgrade...you might as well use premium.
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This is a quote I found on Unichip's website under the FAQ section:

Will I need to use high-octane fuel with the Unichip?

Your engine should always be tuned using the fuel you intend to use. If, for example, you like to race your car on the weekends, two ignition maps can be entered into the Unichip. The first would be for daily driving utilizing low-octane fuel. The second map would be for racing, utilizing high-octane fuel. Switching between the two maps can be accomplished with a simple toggle switch

Do I need to use premium fuel because of better performance? Or do I need it to prevent detonation? Since the EGT's will be higher with a leaner mix I can see the need for premium fuel, however, I don't plan on having the Unichip tuned aggressive enough to reach high enough EGT's inidicating possible detonation, even with mid-grade fuel, Casper, what do you think?

One of my main reasons for getting this thing is to realize better fuel economy. The guys at Tundrasolutions.com report >1 mpg increase in fuel economy. If I have to run premium, that will pretty much negate any fuel savings, and then some. But, who am I kidding, I want the extra power, if I have to run premium I'll do it...
 
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the most aggressive mapping will be tuned to be with 92 octane...trying to use that mapping without running that octane could produce problems with preignition or detonation even with the toyota knock sensors working.

If you are spending that kind of money on it, why not ensure that you get the most power out of it. Im sure that some power can be had out of the unichip with lower octanes but you are leaving safe hp on the table by not running the most aggressive mapping and octane that you can.
 
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