What can a dynojet tell me that autotap won't?
03-27-2002, 07:42 AM
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What can a dynojet tell me that autotap won't? I'm just curious if putting my car on the dyno will help me tune my car better than autotap. Are there some parameters that autotap can't diagnose that a dynojet can? Just curious.
03-27-2002, 07:46 AM
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Re: What can a dynojet tell me that autotap won't? It can tell you your AFR's... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> It would be great if you had an autotap with you though, get records on each run to see if your getting any KR
03-27-2002, 11:00 AM
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Re: What can a dynojet tell me that autotap won't? A PCM scanner does give the info to obtain the AFR, its the 02s, which is converted to AFR.
A chassie dyno only is telling you what was seen while spending about 30 seconds in the run at load conditions.
Recording the PCM on a street drive gives you real world values over a much longer timeframe and to me has more value to performance tuning.
A chassie dyno only is telling you what was seen while spending about 30 seconds in the run at load conditions.
Recording the PCM on a street drive gives you real world values over a much longer timeframe and to me has more value to performance tuning.
03-27-2002, 11:34 AM
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Re: What can a dynojet tell me that autotap won't? The OE O2 sensors are not accurate for tuning. That is the advantage of the wide band O2 used in conjunction with the dyno. But you can't change anything, unless you buy a MAFT (a waste of money) or pop for custom tuning (the right way to do it). FLP and Speed both can do it. I just did this at Speed Inc. Baseline was 341 RWHP.
After custom tuning 361 RWHP.
After custom tuning 361 RWHP.
03-27-2002, 11:45 AM
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Re: What can a dynojet tell me that autotap won't? It seems like dynoing your car is a waste of time and money since the #s always seem to vary. Everyone seems to say that you can't compare 2 separate dynos because the #s won't mean anything. On the same token, you can't dyno at the same place to see what gains you got unless the weather conditions are the same. WTF? What good is it to anyone then? You just get a bunch of worthless HP and TQ numbers and autotapping your car can virtually do the same thing. Is it safe to say that its a total waste of money or is it just me?
03-27-2002, 01:39 PM
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Re: What can a dynojet tell me that autotap won't? Temp use of a wideband 02 is a waste of time for a function that is a LONG TERM value, in any case dyno guy sticks one at the *** end of exhaust after the cat has produced 02 and thus what is seen at tail as to AFR is not any more correct then the existing 02.
O2s are not even used for WOT, thus tuning via 1 wideband on one side of the engine is not anymore correct since both heads are never completly balanced in AFR.
A dyno run is less then 1 minute of time, any change to AFR at that moment of time with the wideband is not even considered for some length of engine run time.
Once the stock 02s are used again then no matter what was tuned via some dyno setup is a mute point since PCM is going to recal back to what stock 02s report.
It is not true that you cannot tune with stock 02's, since they are solely for EPA, smog, part throttle and is not any problem to tune to get close to the 14.7:1 AFR.
O2s can be read ( for our use) during WOT and used as a guidemark to obtain best WOT performance and the .890 mVolts is used as that mark where a stock 02 reports as being close to a perfect WOT calibration.
Too much is put on what the 02s report versus what is the WOT timing, how much MAF flow, any knock or multi misfire and only use 02 reading as a guide marker from one test to another to know if changes were for a positive or not.
O2s are not even used for WOT, thus tuning via 1 wideband on one side of the engine is not anymore correct since both heads are never completly balanced in AFR.
A dyno run is less then 1 minute of time, any change to AFR at that moment of time with the wideband is not even considered for some length of engine run time.
Once the stock 02s are used again then no matter what was tuned via some dyno setup is a mute point since PCM is going to recal back to what stock 02s report.
It is not true that you cannot tune with stock 02's, since they are solely for EPA, smog, part throttle and is not any problem to tune to get close to the 14.7:1 AFR.
O2s can be read ( for our use) during WOT and used as a guidemark to obtain best WOT performance and the .890 mVolts is used as that mark where a stock 02 reports as being close to a perfect WOT calibration.
Too much is put on what the 02s report versus what is the WOT timing, how much MAF flow, any knock or multi misfire and only use 02 reading as a guide marker from one test to another to know if changes were for a positive or not.
