Quick question regarding dyno.

[lil_foy]

Alright so hopefully ill be getting some base numbers from the dyno soon.

Question is do I use 4th gear with a vtir gearbox?

1st: 3.230
2nd:1.900
3rd:1.360
4th:1.034
5th:0.787

Im guessing I would because it is the closest thing to a 1:1 ratio without going below?

Can anyone confirm?

Thanks,
Andrew

[chargeR]

Why does it matter if it is a 1:1 ratio? It isn't going to be 1:1 after the final drive is taken into account.

[lil_foy]

Didn't think of that haha.

Well does anyone know what gear it should be in?

3rd or 4th?

[chargeR]

Didn't think of that haha.

Well does anyone know what gear it should be in?

3rd or 4th?

I have done some work with dynos but not dynamic dyno pulls with cars on chassis dynos. I have only done steady state dyno work. I would run in the highest gear that won't overspeed the dyno. A higher gear means a longer run which means better data resolution.

[FastFwd]

Every time ive had any of my cars on the dyno they have always run it in 4th.

[migoreng]

is there a massive difference between running in gears 3 or 4?

[lil_foy]

is there a massive difference between running in gears 3 or 4?

50kph speed wise.

[migoreng]

i'm talking about the power readings...

[T-onedc2]

For what it's worth my two runs on different dynos are:
3rd = 96kw (cool day)
4th = 89kw (31+ degrees)

[Gio]

lol thats a massive fkn dickhole of a difference.

Looks like 3rd is better haha

[lil_foy]

Ill just ask the tuner like charge-r said so I dont overspeed the dyno.
Dyno figures are mainly for e-penis's imo.

[chargeR]

Ill just ask the tuner like charge-r said so I dont overspeed the dyno.
Dyno figures are mainly for e-penis's imo.

I am not exactly sure whether chassis dynos have limit on how fast they can be spun but I am assuming they do.

[migoreng]

For what it's worth my two runs on different dynos are:
3rd = 96kw (cool day)
4th = 89kw (31+ degrees)

cool..i guess if you did the 4th gear run on a cool day as well you could have seen a few more kw.maybe 92-93?

my stock h22a did 106kw in 3rd which is not bad..considering my sparks were really corroded at the time and i had something like 15-50w oil...

[T-onedc2]

yeah sounds about right, so not much difference between the two methods

[ZeForce]

I did back to back runs in 3rd and 4th about 5 mins apart and there was only a 2kw difference......

[migoreng]

I did back to back runs in 3rd and 4th about 5 mins apart and there was only a 2kw difference......

that's good to know then...my dyno was done in 3rd and after that i wasn't so sure how to compare cause everyone else did theirs in 4th :P

well it was a dyno day so i guess they ran 3rd gear to speed things up?

[ZeForce]

Generally, my car is dynoed in 3rd gear when tuning since it puts less load on the engine

[aaronng]

Originally, 4th gear used to be direct drive where the ratio is 1:1. Not changing ratios mean less power loss through friction and gives you the highest reading.

Now with cars not having a 1:1 gear ratio like yours, we tend to use 4th because that is the longest gear that is not an overdrive (longer than 1:1 ratio). But if you use 3rd, it will still be the same since the dyno goes based on the rolling speed. At 3rd gear, you will have more torque at the wheels compared to 4th but the top speed will be lower, causing reduced power from the calculations and almost evening out at the end.