[LS3] Is the Euro 5 VFII affected by detuning... is it 304?

[lmoengnr]

Yes please. From my powertrain colleages who worked on both variants, they have advised that the engine cals are slightly different (more agressive for the Chev SS). Also the Chev SS stock exhaust is different to the stock Aussie VF2 LS3 exhaust. Chev SS sedan utilises H pipe in the mid section.

View attachment 198404

Similar to a HSV mid section. Do you know the diameter of the pipes?

E3 Maloo 2.5" mid section.

 

[3rspecB]

Similar to a HSV mid section. Do you know the diameter of the pipes?
E3 Maloo 2.5" mid section.
View attachment 198405

2 1/4", same as stock Aussie VF2. A higher grade stainless was used on the Chev SS exhaust due to the US salting their roads in winter.

Interesting that HSV dropped the H pipe and went with an Xpipe in the mid section for VF.

 

[monstar]

I'll ask the question. All the engine/trans work for VF2 LS3 and Chev SS LS3 was done internally by GMH Powertrain so unlikely a J1349 will ever be publicly released. Engine dyne, chassis dynes and ecu/trans cals all done here..

Oh good, perhaps someone could explain why WOT launch loaded in Sports mode that the trans tune uses vehicle speed to change into second at 43 kph, so changes at around 5300 instead of defaulting to WOT shift table and revving out near 6300?
Please show this video example of car shifting early with pedal flat to the floor, notably not revving to WOT shift points defined in the trans tune.

Also on the evidence of nearly a dozen independent dynos the engine develops peak power at 5400, which is 500 RPM lower than previous. Given the assumption is same engine (and camshaft) of 2015 Chevy SS, 304 kW at 5400 would suggest the engine is detuned by comparison.

• Is that to meet emissions requirements?
• What is the peak power output in this state of tune?

 

[PeteSS]

To throw another curve ball, there was a clip on Youtube (can't find it now) where there was a near 10rwkw difference in dyno reading on a VF2 with the bimodal mufflers open, then closed. I assume the 304kw Holden claims would be with the bimodals open

 

[lmoengnr]

2 1/4", same as stock Aussie VF2. A higher grade stainless was used on the Chev SS exhaust due to the US salting their roads in winter.

Interesting that HSV dropped the H pipe and went with an Xpipe in the mid section for VF.

Thanks!

 

[3rspecB]

Found a VF2 Commodore brochure from Holden. Figures quoted using 98ron and per ECE regulations.

So what standards are the aftermarket dyno operators using and from memory HSV quoted max figures are measured in DIN ?

 

[426Cuda]

MY17 transmission tune, WOT shift point 1st to 2nd is 6200RPM with transmission in normal mode.

Mine certainly shifts well beyond 6,000 @WOT too.

 

[426Cuda]

Dyno run of my VF1 with 2.5" GEN-F mid section. Had a few thousand k's on the clock, so not brand new. It was a slug in stock form too, when compared to the VF2.

 

[monstar]

Dyno run of my VF1 with 2.5" GEN-F mid section. Had a few thousand k's on the clock, so not brand new. It was a slug in stock form too, when compared to the VF2.
View attachment 198429

That is not calibrated, shows worse than stock. If it were an outright measurement it indicates less power with the exhaust.

 

[426Cuda]

Really? Spot on, or just up on stock, using the formula you quoted: 260fwkw÷1.27=204.7rwkw.
The mid section exhaust with no tune would add 3/5 of nothing.