dynos and ms3's

[palerider]

Ive been reading up on dynos and correction factors this morning and Ive run upon some interesting concepts. The main point of this post is how MS3s may actually be "immune" to correction factor.... or even run opposite the typical calculations in the formulas.

The first thought is that our cars hate the cold. "Correction factor" loves the cold. I notice in weather below 40-45 degrees my car just doesnt respond as well. More lag, more fuel(runs richer), maybe boost cuts, holds boost worse, maybe even fuel cuts...plus maybe a little tire slipping on an outdoor dyno cause they dont hook up as well. The problem is that when we look at cf... we see that its set up probably for NA engines that would LOVE that cold dense air, not the ms3.

In my case... I was looking over dynos that I had done in the fall and seen my cf had been multiplying by a factor of 1.03, and more recently 1.05. The 1.05 was on a day about 80 with 49% humidity. Last night the temp was 39-40 with humidity of 14%. The correction factor was .99.

This is a difference of 6%...... 6% from my baselines. Now the dyno was correcting my numbers down last night.... and my thought is that temps like that actually make my car run worse too.

So anyway...

October 2007....80 deg./ 49% humidity
MS CAI / RP ......with cf of 1.05
252 hp /283 trq

Jan 2008....40 deg./ 14% humidity
mods in sig.... with cf of .99
265 hp /299 trq

And then.....
a "Palerider MS3 correction factor" ....of my car runs better when its 80 than when its 42.... and thats what the formula should show, but it doesnt, so I'll change it anyway....lol

would be...

265 hp /299 trq multiplied by 6%, which is what the dyno subtracted for "better conditions"... and you get...

281 hp /317 trq.

I guess the argument would be that our car DOESNT run better in warmer weather. Also Im doing this cause Im in the middle of a bunch of work on the car, and I just couldnt believe that...

dp, fmic, cpe standback at 17.6 psi netted me only 13 hp /16 trq. It felt like a shitton more than that the couple of days after it was done.... when temps were in the 50-55 range. Sorry if this wasted your time to read.... but its supposed to be super cold here in NC the next couple weeks and Im not gonna be able to redyno under better conditions. I was bummed and searching for answers.

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Edit... if you all read this and want to flame me I wont care...lol If Im way off the rocker here I want to know.

 

[icespeed]

It seems to me that you couldn't just take the 6% in a "real world" scenario. The humidity plays an important factor, as well as the ECU making corrections because of the temp difference.

On paper, (i.e. mathematically), it is true that cars perform poorer (is that a word?) in a warmer/higher humidity climate. That goes for both N/A and boosted.

Real world wise, other factors are involved that do allow for results to contradict expected outcomes.

 

[palerider]

It seems to me that you couldn't just take the 6% in a "real world" scenario. The humidity plays an important factor, as well as the ECU making corrections because of the temp difference.

On paper, (i.e. mathematically), it is true that cars perform poorer (is that a word?) in a warmer/higher humidity climate. That goes for both N/A and boosted.

Real world wise, other factors are involved that do allow for results to contradict expected outcomes.

Fair enough, I agree. I think the ECU shuts down our cars in the cold. I think it IS the ECU.... On another previous dyno I had with temps in the high 70s, and IDENTICAL humidity(14%) and barometric pressure(29) my correction factor was still 1.03.... even that is 4% higher than last nights 0.99

I simply think my car runs worse at 40deg, than say 80deg.... all things being equal otherwise. This would especially be true considering I iced the top mount to get that run, on the third pull that day.

Im simply saying that CF isnt right on our cars. I in no way am saying that the difference is 4 or 6% or whatever. Just that its something different.

I think this is why there is such discrepancy among our dynos. I think CF ***** it up. It works backwards for us sometimes.

 

[Derek88]

I agree that something IS up with either the CF or something. I dyno'd 248/281 with the CAI and RP in Dec (I think) '07 when it was in the mid 70s. It might not mean much, but when I drove Randy's car yesterday, it felt a hell of a lot more than 20whp/20wtq more than mine...

 

[driver311]

plain and simple our cars dont perform on the dyno in cold weather. I have not been able to dupliate my dyno runs from august. My car is pulling harder, way harder but my dyno graphs are way less. I know for a fact. Around the time I raced that ss camaro my car was trapping 108 and I was at 311whp. I only beat him by one car. Now Im beating that camaro by like 10 cars lengths and making less whp on the dyno. Like 30whp less. I dynoed tonight and the car would only muster 280whp 360ftlbs. with test pipe, cdfp, sri and bc. And trust me the car is pulling way harder with the pump in it. so Ill just keep using the dyno as a tuning tool and only register my mods on a day to day base.
dont let the dyno bust your bubble. Just keep modding and making more power. I always install my mods on the dyno to see what it does day to day. Only way tell truthfull gains.

I know there was alot of speculation on my 311whp dyno. but look at it this way. Stock that same day my car made 238whp and with three bolt ons did 3 runs over 300whp. So the car did pick up that power, and my trap speeds back up that theory. So thats all that matters to me. Ill post my new graphs next week. Though they dont really show s*** compared to trap speeds.

 

[boost_me]

i had a CEL when i ran mines for the first time... bank1 lean O2 sensor b/s.. car ran super duper lean below 10's it just dropped after 4krpms... graph looks disgusting.. in the freakin cold jan 7th ...after i get my txs downpipe/mid pipe installed.. back to the dyno with no CELs

 

[Haltech]

Also remember guys, that people Fudge their dyno results. The smoothing factor some shops use dont use the correct SAE correction, showing higher numbers. This is VERY evident in my experience amoung the domestic boys and have been called out many times.

For instance, there was a Lightning being dyno'd in NJ. This shop has a notorious track record for very high numbers. For instance, a 788hp lightning that can only run a 11.38@121 at Cecil County Raceway. HP value doesnt even match the ET. It should have been in the 10:0x's.

Point is, were are starting to see it here. Also, depending on how much hp the dyno supports, will equal lighter or heavier rollers, which show higher or lower numbers.

Dyno's are good for initial tuning and quick checks to see where your mods are and more importantly, AFRs sit. the track proves the power and the street should always be used for final testing. Why? LOAD.. 100% load CANNOT be duplicated on a dyno.

 

[Bufalo]

dp, fmic, cpe standback at 17.6 psi netted me only 13 hp /16 trq. It felt like a shitton more than that the couple of days after it was done....

It may have only given that much at the peak, but I would imagine there are spots in the power band where you had more. Can you post the two graphs?

 

[palerider]

Thanks for the replys guys. I didnt buy this car to dyno it. I guess Dereks comment is pretty much the most important.

The car is noticeably faster and more fun to drive... thats what this whole gig is supposed to be about.

Its just nice to know that all this sweat, tears, and I guess cash...lol... is amounting to something tangible. When I started modding this thing, it was my first. In the back of your head you really dont know what to expect as the mods build. The dyno, at least in my head, was the almighty scorecard. Well I feel cheated a little bit.

I guess to be able to punch it and actually laugh out loud, a little....is what we're really chasing here. Well Ive got at least that. And also... I am now officially scared of my car sometimes on public roads. As much power as some of my previous rwd sedans had.... they dont touch this joker.

**** dynos.... But I needed to hear it from a few vets first!!

 

[palerider]

It may have only given that much at the peak, but I would imagine there are spots in the power band where you had more. Can you post the two graphs?

Graphs are at work. I'll try to get them up tomorrow. HP was up around 20-30 all the way to about 5000... it flattened at peak as boost fell off. But I made more past peak too.

Trq was 10-20 higher across the board.

I still say the dyno was jacked though. It was a bad cold day. Driving it today with weather in the 30's I was getting my first fuel cut ever. It would be stupid fast(normal) and then act weird and slow... the car was all over the place. My gas mileage even had me worried it was so horrendous.... even for the way I was driving it. The ECUs on these things suck crackpipes in the cold. The fact that the dyno punished me so much further with CF just added insult to injury.

I got to get that pump back on. And the two weeks that NC usually has winter needs to end soon..lol

 

[jp4130]

I thought you could turn off cf?