Well, guys I got my car re-dyno'd this past Saturday. It is VERY interesting to me.

A little history. Last year (April) I got my car dyno'd. It yielded around 281.8whp and 306wtq. I had my stock 16" wheels/tires on (overall weight = 46lbs/ea). It was approximately 45 degrees out that day. I also had a cat that was probably close to being full blocked; unknown at the time but now known.

This latest dyno tune was with my new 19" wheels and 275 tires (overall weight = 60lbs/ea). It was around 75 degrees out. I had replaced both cats up front to new. This time I got 275.4whp and 287wtq.

HOWEVER, when I FIRST brought my car in that day I was only getting around 265whp (I didn't note the torque)! So it deviated (went down) by about 15whp from last year's dyno probably due to the day being 30 degrees hotter outside and that I had my larger, heavier wheels on it...perhaps some of the loss was even attributed to the ECU "over-powering" the Apexi Neo tune over time.

In any event my new results are 275.4whp and 287wtq at 75 degrees out WITH my 60lbs 19" wheels/tires combo.

He said my car was running VERY VERY lean when I first brought it in. He added some fuel to it. I think he said he tuned it so it was around 13.0 fuel. So when it was all said and done at the dyno shop I added 10whp and around 15wtq that day. I bet this new tune (and results) are better than my last year's dyno eventhough my numbers went down. I BET if I were to put my 16" wheels/tires back on and it was 45 degree outside I would yield MORE than my previous 281.8whp / 306wtq results. I think it would be closer to 290whp.

The car definitely feels noticably stronger after the dyno. It's crazy, I guess 14lbs/ea corner slows the power down alot!

Comments?

 

This was a different tuner than the first two?

You mentioned "perhaps some of the loss was even attributed to the ECU "over-powering" the Apexi Neo tune over time."
Can you go into detail on this as I just got my Neo..

Nice work.

 

I decided to go with the same tuner/shop again. I read in many places that a tune on any car can slowly revert back to the stock ECU settings. This happens mainly on piggback computers (like the Neo). If you get a stand alone EMS (like Haltach or Greddy)...the tune will never deviate.

 

I know Denut-L had dyno numbers of 271.98whp and 284.5wtq about a month ago; he has basically the same mods as me and also had 19" wheels on w/275 tires at that dyno session. However, he has a GS430 where I have a GS400. Perhaps that slight difference is outside temperature (eventhough a month ago and up in MN it would have been colder than my 75 degree day). It could have even been my Torque Master plugs. They do say that they yield around 5whp.

 

Nice numbers rock! It's kinda weird with the discrepency in your numbers from now and the last time you got it dynoed. I guess that 30*temperature difference and heavy wheels made a big difference. How does the car feel? Does it feel like it is faster than last time you got it dynoed?

 

Hard to say, because last time I left the dyno shop on my much lighter 16" wheel setup...the car felt peppy and strong. Now it still feels strong but it is hard to tell. All I know is that I bet if I throw my other smaller wheels on it will probably feel faster that it did last year. Again, I think this tune was better (pushing the AFR's a little more to 13.0) and the fact that my cats are now new; the old ones could have been hurting the figures last year. I think iirc the tuner said my AFR's were around 13.1-13.2 last year. He also said that the range for NA cars is usually 12.8-13.2 to avoid detonation/engine blow up.

 

Was there, 65* or so, I had my corvette with the top dropped, so it wasn't too bad actually. IIRC for any car, NA or FI, the sweet spot for the A/F ratio should be around 13.5 @ WOT. Long's, Denut-L's, GS was on the money pretty much the entire range, which meant he wasn't squeezing any more ponies for his setup. One thing to note is that he has a 3.92 diff, you have a 3.76. Like you mentioned, you ignition systems are identical, but anyways... I just wanted to say that although your peak numbers might not be what you wanted, I think your close enough that on the streets you wouldn't be able to tell the two apart. You have to keep in might the driver, dyno, traction, ambient temp, engine temp, exhaust temp, all weigh in on the over all performance or numbers. I would like to point out that very few engines make 200+hp throughout the entire engine range. And if 300hp is the overall final number that can be achieved from this 4.3L beast, without cracking the valve covers, I am fine with that. I think the more this goes on, the more votes there will be for a motor swap..... On that note, does anyone wanna buy my GS430?

 

Actually, where I am on L.I. it was about 72 degrees at around 1PM.

http://www.wunderground.com/history/...ename=New+York

 

This is why it happens. Your ECU calculates short term fuel trim based on data from many sensors, including TPS, MAF, IAT, ECT, O2, and whatever else I might be forgetting. However your piggyback only modifies the MAF data, so the computer is still gets the data from O2 sensors that are reading rich, and it will lean out the mixture, and modify its long term fuel trim based on previous short trim calculations. By retuning your Neo you're only going to cause a lot of confusion for your ECU, because you're modifying your MAF sensor data even further to enrich the mixture, and the ECU will lean it out more eventually.

My suggestion to you is, disconnect the Neo, reset your ECU and drive for a few days, let the computer set proper long term fuel trims. Then hook up the Neo, retune it, and set the throttle point REALLY high, like 90-95% or so, this way your short term fuel trims wont get affected, and in turn they wont affect long term fuel trim.

 

Rock, not sure if you thought I was talking about being there, but I was talking about Long's Dyno session, in Minnesota. I was just saying that I'd imagine that the temps were that far off because it was a fairly decent day here. Either way your car is pretty damn tight.

I haven't dealt with too many AFCs on Toyota's, but I'd imagine there is some sort of relearning, but for the most part, the AFC uses a wideband to read the signal, and from what I remember Long's GS430 was pretty much on the money without having to adjust it much, however the factory ECU is going to go for 13.5 as much as it can with short term and long term fuel trim strategies, but if everything is within range, an O2 sensor will just reads as normal.

 

Imagine what access to a dyno for a day could do, eh? I wonder what the difference would be with and without your 19s? Hot engine vs. cold. Cool morning air vs. mid-afternoon humidity. Reset ECU vs. non...

I would guess variables like those could easily deviate an engine's output 10% with the right combinations.

 

Nice numbers Rock
Even though we all aim for the high numbers everyone should remember that like it's been mentioned here, every dyno's gonna read different numbers due to alot of things. Tire pressure, Air temp, Sea level, certain dyno machines, Ect ect. I had my car dyno tuned last year and at my first tune this year the AF didn't changed at all. Jordan "tuner" said there's not much he could do to the air fuel as it was already pretty much on spot and just touched it up here and there. What matters the most is getting your AF on spot with your setup. And from my experience before and after is so much BetteR! My only way to know if anything improved after mods and dyno tune, race someone i raced before and see if i can keep up or pull ahead.

I was once told by a guy at a shop that depending on whoever's tuning your car and how they setup the dyno machine can make a difference in your output numbers. Like for example on dyno days, some shops usually bump it up a bit for better numbers and a better show and smaller shops would do the same thing to keep they customer coming back. Interesting stuff here

Got any video's Rock?

 

VVT-i is messing with your tune...

Did you reset your ecu?

VVT-i controls the timing, and 'learns' your driving patterns. If you drive like a granny, it's going to shift slower, lean your AF to get more gas mileage since you don't need it the extra fuel, as you are keeping a constant speed/slow acceleration.

If you romp around town all the time, you get less mileage, but your car is 'peppy' and quicker to shift, more prone to hold the gear longer...I notice this when I do a long range trip, the car does not accelerate through stop and go city driving as quickly as it would before the long range trip.

Maybe that'll help. The wheels also will hurt your HP output with that extra rotational mass=more energy used to push the wheels rather than the whole car.

Whats next? Porting/polishing? Supercharger? Full custom exhaust? ITB's? LOL!

If there were a way to disable your VVT-i, you could probably get a better tune, and it'd stay constant. Maybe a Non VVt-i cam, as well as a custom ECU would do the trick.

 

LOL, I ported and polished


no, I just cleared up some knots on our cats... u know, the weld knots. Since, it was out for over 3 months, I might as well and it doesn't hurt since it's a thick as steel weld. I think i gained .001 hp/tq YEAH!!!

Acutually, it's a lot more responsive than I remember. Just a touch of the pedal and the car was eager to go real bad. There might be something there besides going straight pipe.

 

Its not just the weight of the wheels Rock...lot of people think it is. Its also the rotational mass. Bolt up those 16's and see....