LS1 Monaro New Owner, disappointed with power figures

[Xpuffin]

ARAF said:

No, 6 years ago, from the above post.

I recognise the reg from somewhere, has the car been to a HSVDyno Day in the past.

[ringram]

IMO its AFR thats dropping it down a tad.

What do the plugs look like?

Not sure what MF tunes are like these days they might have changed commanded AFR since 6 years ago! Give Roger a call to discuss.

[M11 MFP]

Bottom is a stock LS1 with stock tune and cast manifolds.

2nd up is a stock L76.

3rd up is the mighty E39 M5 with 398 fwhp from factory?

4th is a 'Focus Pack' with 85mm MAF, longtubes and MF tune .

5th is a 243 head LS1, with 1 7/8" mid length headers and a stock GM tune... note the torque loss with the big headers and 117.5 LSA cam.


Probably not a lot wrong with yours on this basis, bar picking the AFR up to 12.5/13 :1. Ignore that flywheel figure. It's a fudged estimate and may be a bit low.

SRR is not optomistic unlike some others. The focus pack car has recorded near 320 rwhp elsewhere

Edited by M11 MFP on Monday 25th August 21:23

[wozzza]

I can say that my completely stock 04 VXR made 300rwhp (299.6 according to the dyno, it's basically 300).

That was at a dyno here in the northwest, that someone attended and then went to SRR and they were very very close. I believe within around 5RWHP or something around there. So basically identical in reality.

Edited by wozzza on Monday 25th August 21:41

[Mr C v8]

Yes 4th one from bottom is mine, here's my last 2 graphs.

1st was in 2012 when the focus pac was fitted and 2nd in 2013, the only difference for the 2013 run
Was I had the 3.9 diff fitted which on paper looks like I lost 19 rwhp.

The AFR is the biggest between ours.

Ian

[psycho sport]

Why or how does a different rear diff change the at the wheel figure?!

[Mr C v8]

psycho sport said:

Why or how does a different rear diff change the at the wheel figure?!

Who knows, but I'll be there again this year to see what it is this time.

[ringram]

Mr C v8 said:

psycho sport said:

Why or how does a different rear diff change the at the wheel figure?!

Who knows, but I'll be there again this year to see what it is this time.

Because I understand there is more friction and power loss in the gear reduction. A more direct gear is better, hence why usually dyno is run in 4th which is 1:1
Holden Monaro's fair better here with their gearset than the HSV's
3.9's are worst.

[ARAF]

psycho sport said:

Why or how does a different rear diff change the at the wheel figure?!

Probably because the ratio wasn't factored in to the dyno calculations correctly.

[ringram]

ARAF said:

Probably because the ratio wasn't factored in to the dyno calculations correctly.

Nope, they do eat power.. Its a direct measurement remember. The benefit of a chassis dyno..

Gearing is just to match up RPM axis on the dynosheet. Im sure Charlie will fill in the details.

[M11 MFP]

ringram said:

Nope, they do eat power.. Its a direct measurement remember. The benefit of a chassis dyno..

Gearing is just to match up RPM axis on the dynosheet. Im sure Charlie will fill in the details.

Can't be converting an additional 12kw to heat in the diff though. It would be cremating eggs rather than frying them. Must be something else going on with the 3.9, some shared inefficiency throughout the whole driveline.

[ringram]

Yeah it is, for each wheel turn the drive shaft, trans, flywheel etc are all spinning higher surely?
If you do some reading you will see figures of 5% extra loss bandied about.

[ARAF]

ringram said:

ARAF said:

Probably because the ratio wasn't factored in to the dyno calculations correctly.

Nope, they do eat power.. Its a direct measurement remember. The benefit of a chassis dyno..

Gearing is just to match up RPM axis on the dynosheet. Im sure Charlie will fill in the details.

Vixpy, you're wanted.

Why don't you use first gear for dyno running, so that everything happens much slower?

[SturdyHSV]

ARAF said:

Vixpy, you're wanted.

Why don't you use first gear for dyno running, so that everything happens much slower?

Wouldn't that mean loads more torque at the rollers, meaning more risk of tyre slip and equally the rollers would need to be able to cope with easily 3 times the torque? Or have I just made a fool of myself?

[ARAF]

SturdyHSV said:

ARAF said:

Vixpy, you're wanted.

Why don't you use first gear for dyno running, so that everything happens much slower?

Wouldn't that mean loads more torque at the rollers, meaning more risk of tyre slip and equally the rollers would need to be able to cope with easily 3 times the torque? Or have I just made a fool of myself?

That's my argument. The gearbox acts as a multiplier, and as the power is calculated from the torque.....

We may be fools together, but dyno controllers always try to use which ever gear is as close to a 1:1 ratio. As has been said, 12kw of additional power loss in a different diff would be the equivalent of four kettles being boiled.

[Vixpy1]

Got myself in enough trouble posting the the Dyno day thread

[ARAF]

Vixpy1 said:

Got myself in enough trouble posting the the Dyno day thread

Think I'll have to pick your brains on 18th October then.

[GaryNoGrip]

Bhp figures can be an obsession, I often find my self wanting my 388rwhp from my audi back, over 100 down with the ute, BUT I have soooo much more fun after all grip is not for everyone...

[Mr C v8]

Well the 3.9 diff feels better for it on the road, it's that old question I guess
do you want it set up for the road and what it drives like or dyno numbers...

















...both please

[psycho sport]

Just a quick update.

Had plugs, leads and air filter changed. The difference is fairly impressive! WIll be good to see the results on the dyno in October.

Also swapped the 'quiet' exhaust option on the Wortec exhaust to the loud option… my good god its loud!! not sure its to my taste but for the time being its quite amusing.

Cheers for the help