E39 GMH 3.0 SIDI: 91 vs 98 Octane

[swingtan]

OK, a bit of an update on all this....

Firstly, cam timing:

I'm finding that increasing the intake timing sooner helps a fair bit. The timing table don't allow for -ve timing, so I'm assuming at the moment that the setup is a bit like the Honda VVT-I or Rover VVC setup. So there are two main points to consider.

1. Advancing the Intake cam increases cylinder filling efficiency, but also increases exhaust overlap.
2. Advancing the exhaust reduces overlap when the intake is advanced.

So the idea here is to advance the exhaust at low / light cruise to reduce pumping losses (maybe), and increase economy. Also have the exhaust and intake advanced at lower RPM high load to both reduce overlap and improve cylinder fill. Ten at higher RPM, bring the exhaust timing back to "0" advance to increase overlap and use the exhaust pulse to help fill the cylinder. Anyway, that's the theory. Get the timing wrong though and you get the exhaust contaminating the intake charge....


Secondly, I get the feeling that the standard injection timing is too late. Especially in the lower RPM / high load cells. Given the valve timing, I'm going to try and advance the timing a bit to see if that helps. Other than that, the last big test showed fairly good results. Averaging 13.5L/100KM while towing a large cage trailer full of holiday gear. It pulled OK for the V6, but I still miss the cammed 6Lt when towing.....

[Boost]

OK, a bit of an update on all this....

Firstly, cam timing:

I'm finding that increasing the intake timing sooner helps a fair bit. The timing table don't allow for -ve timing, so I'm assuming at the moment that the setup is a bit like the Honda VVT-I or Rover VVC setup. So there are two main points to consider.

1. Advancing the Intake cam increases cylinder filling efficiency, but also increases exhaust overlap.
2. Advancing the exhaust reduces overlap when the intake is advanced.

So the idea here is to advance the exhaust at low / light cruise to reduce pumping losses (maybe), and increase economy. Also have the exhaust and intake advanced at lower RPM high load to both reduce overlap and improve cylinder fill. Ten at higher RPM, bring the exhaust timing back to "0" advance to increase overlap and use the exhaust pulse to help fill the cylinder. Anyway, that's the theory. Get the timing wrong though and you get the exhaust contaminating the intake charge....


Secondly, I get the feeling that the standard injection timing is too late. Especially in the lower RPM / high load cells. Given the valve timing, I'm going to try and advance the timing a bit to see if that helps. Other than that, the last big test showed fairly good results. Averaging 13.5L/100KM while towing a large cage trailer full of holiday gear. It pulled OK for the V6, but I still miss the cammed 6Lt when towing.....

Thanks for the great info! You know that little engine runs pretty ok in the rental car Impalas here, though not towing anything - just floored everywhere with T/C off...

I imagine on my (very) turbocharged car, there would be some special considerations or is the theory the same?

[GMPX]

Sorry Simon, IMHO it's a horrible engine, well, in something as heavy as a VE Commodore it is. Drive the 3.6L version and feel the difference, 0.6L can't make such a big difference so there is just something fundamentally flawed with the 3.0L. My opinion is maybe a little tainted now too given ours won't make it between services before running out of oil.
Not that it matters now with Holden shutting down, but they should have offered the Colorado's 2.8L Diesel in the VE, with 500Nm of torque and better fuel economy that the 3.0L SIDI, why not?
Boost, I'm pretty sure the Impala rental cars are all 3.6L (LFX) SIDI engines, that is why they feel ok and that is the only V6 option Holden should have had for the VE. Unfortunately the LFX was only available on a select few models for us.

[swingtan]

No, I agree. The 3.0 is too small for a heavy VE Wagon. But looking at the exhaust manifold, I'm sure Holden was thinking of twin tubos. With just a small amount of boost I'm sure the motor would be significantly better.
With boost, I'd probably be advancing the exhaust cam a little more and leaving it it advanced all through boost to reduce chances of the intake charge blowing straight out the exhaust. Maybe a little less intake advance is needed as well as a boost will fill the cylinders.

[GMPX]

But looking at the exhaust manifold, I'm sure Holden was thinking of twin tubos.

If they were considering that they could just use the LF3 TT 3.6L from the current Cadillac range (which has got the same single exhaust port), however I think the cost of a TT SIDI V6 would be far greater than the good old 6.0L GenIV so I don't think anyone would consider paying more for a V6 than a V8 in a Commodore even if the potential after mods would be pretty good. I am still surprised Holden dropped the 3.0L in the VE, anyone who has driven one complains about how much they continually struggle to haul the VE's 1,850 kg weight around, surely in their early testing on development vehicles they would have found the same thing and decided the 3.6L should be the only V6 option.
Not only that, in many motoring tests it was found in real world driving (not the BS manufacturers Fuel Econ tests) the FORD 4.0L 6cyl and the Chrysler 300C 3.6L V6 get better economy and are nicer to drive than the GM 3.0L. But this is to be expected when the 3.0L engine makes peak torque at around 5,200 RPM.

[Boost]

With boost, I'd probably be advancing the exhaust cam a little more and leaving it it advanced all through boost to reduce chances of the intake charge blowing straight out the exhaust. Maybe a little less intake advance is needed as well as a boost will fill the cylinders.

Thanks, I will definitely try that!

[Boost]

Boost, I'm pretty sure the Impala rental cars are all 3.6L (LFX) SIDI engines, that is why they feel ok and that is the only V6 option Holden should have had for the VE. Unfortunately the LFX was only available on a select few models for us.

Hmm, I really thought so too. But I am almost sure I remember that I was shocked to see 3.0 on the engine cover of one I drove. Then again that was a while ago.

[3L SIDI]

i couldnt complain about my 3.0L SIDI After dyno tune ross its been hauling ass & its got torque broken another drive shaft & also it chirps between gear changes full open throttle u need traction control turned off other wise it just kicks in every shift point lol

also i it down to 6.8L Per 100km on the highway average speed 110KM/H @ 2,000RPM cause i have 3.70 diff ratio on the 6speed auto

[3L SIDI]

Ross i found that hidden Torque communication wire! left passenger under the seat its a clear almost see through wire hard to see yank it real hard so it disconnets & should be good to roll

https://www.facebook.com/photo.php?v...04653171250020

[auspeed]

Does anyone have 12654753 os that they can share for a VF 3.6 sidi ute please?


Salesmake: Holden
Model Year: 2015
Model: VF COMMODORE
Engine: 3.6L (LFX)
Controller: K20 Engine Control Module
Function: Programming