3.8L V6 Automatic, any tips?

[nemo]

I have 2006 Grand Prix and the shifting may not be identical but here is my experience.
I use the 2000 rpm shift also, but have found the letting off to force the up shift to third to be counter productive. If you add more load in third you can get it so it will go in to 4th and lock quicker. This is were the gauge would really help out. No I can't hit this every time even with a gauge. If you do get it right you will know it. It will pull and shift smooth right up to lock up.

If you haven’t read the “108 hypermiling / ecodriving tips” do so, much wisdom there. On a recent trip tip # 14 was proven with the ultra gauge I was driving in to a head wind and tucking back in line was good for 2 mpg and this was at a safe following distance.

14) The 'corridor effect'
All else being equal, traveling at a constant speed on a freeway within a flow of traffic (in the same direction) is more efficient than going the same speed in isolation. The reason is aerodynamic: a flow of traffic generates a localized wind current in the direction of travel. You will benefit from this artificial breeze.



Looking forward to seeing your results.

[ShadeTreeMech]

What tire pressure are you using? For a weighty car such as the Regal, inflating to sidewall max will decrease ride quality, but since you are on the highway quite a bit and the Regal has plenty of ride quality to spare, going up to 44 psi may not be noticeable, except at the pumps. Some good quality tires allow up to 51 psi as well.

What condition is your oil? If it's not been changed since Moses part the Red Sea, newer oil will help. Blocking the grill is another invisible mod that can help with the aerodynamics, and just making sure the OEM underskirting is in good shape can help. Many of the GM products have an air deflector roughly below the radiator that can be damaged over time; checking on its repair is likely to pay for itself rather easily.

As far as whether to allow the downshift, keeping it in top gear is likely to be much better, the 3.8 is crazy for low revving torque. Take advantage of it by staying in locked up torque convertor.

[ktaylor]

Originally Posted by nemo

I use the 2000 rpm shift also, but have found the letting off to force the up shift to third to be counter productive. If you add more load in third you can get it so it will go in to 4th and lock quicker. This is were the gauge would really help out. No I can't hit this every time even with a gauge. If you do get it right you will know it. It will pull and shift smooth right up to lock up.

I'm pretty sure we have the same transmissions in our cars. One question, are you saying not to let it drop into third when the TCC locks-up, but keep it around 2000 rpm until it shifts to fourth? That kind of makes sense just to get it in there faster.

I have read through the tips page (more than once) and know of the corridor effect. It's hard to do when the flow is 100-105km/h and I'm putting along at 90. It nice when I can sit behind a semi who's not doing much faster.

Originally Posted by ShadeTreeMech

What tire pressure are you using? For a weighty car such as the Regal, inflating to sidewall max will decrease ride quality, but since you are on the highway quite a bit and the Regal has plenty of ride quality to spare, going up to 44 psi may not be noticeable, except at the pumps. Some good quality tires allow up to 51 psi as well.

What condition is your oil?

I'm running my tires at 50psi right now. My tires are the latter ones mentioned with the 51 psi sidewall max. I noticed a huge difference right away after doing this too in FE and rolling distance, and you're right, I've noticed very little change in ride quality. What do you mean by "except at the pumps?"

I do need an oil change soon but had one done a little over 3 months ago. Before that was around 8-14 months

Any thoughts on that syncromesh trans fluid?

I might crack and buy an ultragauge, they're only like $60 right now on sale. I'm worried it'll make me too crazy about FE though...

[Sularus]

I have a 01 grand prix gt. I usually hold around 2200- 2500 until in fourth which is around 45mph. Our cars use the same transmission, but the final gear ratio may be different. The Grand Prix GTs use a 3.29 final, the GTPs use a 2.93 final, the 00-05 chevy impala uses a 3.05 final.
Don't use synchromesh, that is for manuals. Use the GMs new Dex VI. I have changed the tranny fluid in my wife's impala and my grand prix. The car shifts better and coasts much easier now.

[ktaylor]

Originally Posted by Sularus

I usually hold around 2200- 2500 until in fourth which is around 45mph. Our cars use the same transmission, but the final gear ratio may be different. The Grand Prix GTs use a 3.29 final, the GTPs use a 2.93 final, the 00-05 chevy impala uses a 3.05 final.

Yeah I have the 3.05 final in mine. Is a larger final drive better for FE or better for accel? Thanks for the info on the trans fluid, I was kind of curious about it.

Did you use a scangauge to decide to hold 2200-2500 rpm until fourth? I'm curious as to how the numbers differ between going to TCC lock-up in third as compared to this. It could make a huge difference in my commute as 80% of the lights I hit are on 70-80km/h speed limit roads where I have to get into fourth anyhow.

Thanks a lot for your input everyone.

As an aside, does anyone know how to set my image below as a link to the fuel log page?

[Sularus]

The lower the number for a final drive=better FE, but slower accel. With my GP I use my factory econ gauge (i know it isn't very accurate, but its all i got). I determined the little extra throttle gets up to speed quicker and I my average mpg is higher at the end of my trip. I may be wrong, but it has worked so far.

[ktaylor]

Originally Posted by Sularus

I determined the little extra throttle gets up to speed quicker and I my average mpg is higher at the end of my trip. I may be wrong, but it has worked so far.

You're numbers don't lie. I'm glad I learned about that cause that should be a nice booster. Maybe I can hit the 30 mark after all.

I wish I had one of those computers... The GS model of my car (with the supercharger) has one built in below the tach but mine doesn't. I'm sure the ultragauge is a lot less expensive tho

[SentraSE-R]

UG is $60 - about the price of a tank of gasoline this Summer .

[ktaylor]

Yeah I know what you mean. If I run my tank down to 10 or so litres, it'll cost me over $70 to fill it. I put in about that much every week right now...

[nemo]

Originally Posted by ktaylor

I'm pretty sure we have the same transmissions in our cars. One question, are you saying not to let it drop into third when the TCC locks-up, but keep it around 2000 rpm until it shifts to fourth? That kind of makes sense just to get it in there faster.

Went out this morning to get this fresh in my mind car is not a dd. I start out using the 2k about 40% load it shifts from 1st to 2nd. When it shift out of 2nd, at this point there is a larger rpm drop, I hold a constant pedal position. If I do it correctly I can reach 4th with it locked up at 38 to 40 mph (61 to 64 kph). After some checking my transmission has overdrive gear for 4th at .7 and a final drive ratio of 3.05.