club.liberty.asn.au

jslayz wrote:Do you have a pre mods dyno figure on the same dyno?

J

No I wish I did, but unfortunately I didnt want to pay for the dyno time before the mods.

The first log is after the dump pipe, panel filter and tune.

The second log is after muffler, resonectomy, CAI, 3port, BOV, silicon intake and retune.

TheFirstEskimo wrote:Thanks for the info guys, very informative. So given that I drive an auto, I have come to the following conclusion...

My second run on the dyno (hub type), produced a maximum of 226.2 hp. If I covert this to kw by multiplying by 0.745699872, then apply a derating factor of 25%, Im left with a figure of 126.51 kw atw.

Does this sound reasonable? Car is not stock and has had exhaust mods and engine mods done.

Guessing your car hasn't had a custom tune to take advantage of the mods?

Technically you haven't done the calculation correctly - As I mentioned previously, there is a formula which involves rolling diameters among other things that will allow you to semi-accurately calculate fly wheel / engine power & also converting to ATW power. BUT, in this case, my estimate would be your not far off. Maybe around 135kw ish which has brought you into line with a manual version.

The old rule of thumb was to subtract your approx 30kw from you Hub power to give you ATW power. This "seems" to reign true in the Gen 4's, but is in no way accurate that's for sure.

jslayz wrote:Do you have a pre mods dyno figure on the same dyno?

Don't know if it helps the OP, but I had my GenV GT dyno tuned before any performance mods were done - so this is a real world example of stock vs. modded + tuned. Graphs are here in my profile thread. Stock atw was 149.5kw. I guess an 07 GT would be a bit less than that.

satogixxer wrote:

jslayz wrote:Do you have a pre mods dyno figure on the same dyno?

Don't know if it helps the OP, but I had my GenV GT dyno tuned before any performance mods were done - so this is a real world example of stock vs. modded + tuned. Graphs are here in my profile thread. Stock atw was 149.5kw. I guess an 07 GT would be a bit less than that.

Oh and I guess I should mention the Subaru engine rating for the GenV GT is 195kw, which in my case equated to stock atw of 149.5kw. Maybe helps.

TheFirstEskimo wrote:Thanks for the info guys, very informative. So given that I drive an auto, I have come to the following conclusion...

My second run on the dyno (hub type), produced a maximum of 226.2 hp. If I covert this to kw by multiplying by 0.745699872, then apply a derating factor of 25%, Im left with a figure of 126.51 kw atw.

Does this sound reasonable? Car is not stock and has had exhaust mods and engine mods done.

That's assuming a 25% loss due to the wheels? Hub dyno is different to an engine dyno.

Guessing your car hasn't had a custom tune to take advantage of the mods?

Yes I have, both times.

The old rule of thumb was to subtract your approx 30kw from you Hub power to give you ATW power. This "seems" to reign true in the Gen 4's, but is in no way accurate that's for sure.

Why would you subtract 30kw for atw if power is already measured at the wheel hub?

After all this, I may just be reading my results incorrectly because that seems to be a really low result overall. Would anyone like to take a look at the results?

TheFirstEskimo wrote:

Guessing your car hasn't had a custom tune to take advantage of the mods?

Yes I have, both times.

The old rule of thumb was to subtract your approx 30kw from you Hub power to give you ATW power. This "seems" to reign true in the Gen 4's, but is in no way accurate that's for sure.

Why would you subtract 30kw for atw if power is already measured at the wheel hub?

After all this, I may just be reading my results incorrectly because that seems to be a really low result overall. Would anyone like to take a look at the results?

I would've expected more power with a custom tune & basic mods based on results others have gotten. Could be a simple as the dyno you were on reads low

As I said, what I have stated is an old rule of thumb that in the past has reigned true with the Gen 4's. Heck, I've had people suggest to remove 40kw from the Hub readings! On a hub dyno, you remove the variable of the wheels & tyres. As mentioned in a previous post, things like tyre pressures, rolling radius, etc can effect the ATW's reading thus why your Hub power is different to ATW's power.

As an example, my ute got 343hp (Approx 252kw) at the hubs after a tune & few bits & pieces... It base lined at 290hp, so I was happy with the gain & the car drives a heap better... If I was to apply that "rule of thumb" it would mean I have approx 222kw ATW's, which, based on others results, is about right. However, if I applied the same thing to my base reading, it doesn't make sense as a standard SS Auto produces around 190-200kw ATW's... Use this stuff as a guide

Bottomline is, don't get too rapped up in all these figures. If the car goes / feels better then that is all that matters