Cee_mon

Someone was mentioning how different tire sizes can affect dyno readings...It made sense at first, but i dont know to what affect it would cause on the numbers?

So does it affect the dyno numbers and what would yeild smaller/bigger numbers?
Thanks

DIRep972

iTrader: (1)

No, nor does what gear you dyno in.

mrbsponge

yes it actually does, tire size, and gearing, also what gear you use, DOES make a difference.

example: my 99 cobra made 302@ the wheels with 327 gears i switched to 373 and now made 338, hows this? because the gear let the motor work so much easier.

i also had no changes to my civic, but we couldnt figure out why my turbo was spooling later and not making the same power it did a month earlier, then we checked the notes on the dyno sheet, and we found out it was done in 3rd gear the time before and 4th THIS time.


so from what i have seen, and done it does make a differece.

boostincoupe

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DIRep972 &raquo;</TD></TR><TR><TD CLASS="quote">No, nor does what gear you dyno in.</TD></TR></TABLE>

B.S.



3rd gear vs. 4th gear pull, back to back. No changes whatsoever.

3rd gear netted 6whp and 1 ft/lb of tq.

BME1986

Which gear do most people dyno in? 3rd or 4th?

roydogg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BME1986 &raquo;</TD></TR><TR><TD CLASS="quote">Which gear do most people dyno in? 3rd or 4th?</TD></TR></TABLE>


I have and seen plenty of people dyno in 4th.

95GSRTT

gears do, tires? umm no

DIRep972

iTrader: (1)

Do any of you guys know how a dyno works? It doesn't know what gear you're in, nor does it care.. A dyno only knows two things; MPH(speed of the roller) & RPM(tach signal). No matter what gear you are in, or tire size you have, or final drive/rear end you have, the dyno automatically calculates it out to a 1:1 ratio. Might wanna look elsewhere for your power gains/losses.

Cee_mon

Well we all know that tire size affect your speedo in your car....so it kinda made sense that it may also alter the dyno.
Anyone have anymore info on this? And iam not talking about tire width or traction...iam talking going from say a 14in rubber to a 16in or something.

DIRep972

iTrader: (1)

Tire size only effects your speedo because it is calibrated for the roll out of a stock tire. Like I said earlier, the dyno doesn't know nor care what size tire you have. It gets your speed based off the velocity of the roller.

daredevil003

every dyno place i know, will always dyno your car in 3rd gear. So 3rd gear is best for the dyno.

BoostR41

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by daredevil003 &raquo;</TD></TR><TR><TD CLASS="quote">every dyno place i know, will always dyno your car in 3rd gear. So 3rd gear is best for the dyno.</TD></TR></TABLE>

no 4th gear is closer to 1:1 ratio and also better for tuning. tire size will affect somewhat since tire size affects gearing

PrecisionH23a

Air pressure comes into play also... less resistance.

HybridKOOP

I have heard tire size makes the MOST difference on a Dynapack!

Tchleung

4th egar is ncier to tune with because it really shows you the flaws in your tune. in 2nd and 3rd gear what may seem like minor no biggy flawd, will turn uot to be pretty decent flaws in a logner 4th/5th pull.

Quad-Damag

i have herd you can gain power from going from 18inch rims with good tires will show lower dyno numbers, then a light weight 13 inch rim. with good tires

SYD

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Quad-Damage &raquo;</TD></TR><TR><TD CLASS="quote">i have herd you can gain power from going from 18inch rims with good tires will show lower dyno numbers, then a light weight 13 inch rim. with good tires</TD></TR></TABLE>

i think that has more to do with the parasitic losses from weight.

MattsHatch93

i know what gear it is in doesnt matter, when i dynoed my beater s-10 at school i did a 2nd,3rd, and 4th gear pull and they were all within 3 hp and 4 ft lbs of torque. BUT tire size i think does matter cause a smaller tire will take strain off the engine, almost like putting a lower gear in it.

mrbsponge

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bruceleeroy &raquo;</TD></TR><TR><TD CLASS="quote">

i think that has more to do with the parasitic losses from weight.</TD></TR></TABLE>


this is what i was talking about!

when you see a diesel truck get dyno'd they never have the 38inch supper swampers on it, they always have stocks on the back.................why..........because 38 inch tire soak up so much power in weight and rotating mass, plus the engine has trouble spinning them if the gear ratio isnt corrected.


im sorry but smaller tires will help you move a roller FASTER than a 20 inch tire on the same car.

SFWD 1934

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HybridKOOP &raquo;</TD></TR><TR><TD CLASS="quote">I have heard tire size makes the MOST difference on a Dynapack!

</TD></TR></TABLE>

I love it . . . LOL!!

Jason