Dealer Called
Senior Member
Joined: 11-27-2007
Posts: 1,115
From: Austin, Texas
You will be suprised about how well the mileage holds up even with a fair
amount of WOT. I have 3500 miles on my GXP with same motor and get
32 mpg on hwy and even with a fair amount of town driving and hotrodding
i almost never see less than 25-27 average. HHR will not be as good
because car was 300 # more but still I think you will be happy with
the mileage. I have a DashHawk and have done datalogging on air/fuel
and because of the direct injection and the in cylinder cooling that comes from injecting fuel straight into the cylinder, the engine runs lean much more
than a port fuel injected engine. Because of electronic throttle and the way it
is calibrated, the engine acts 'diesel like" in the way it is able to mimic the
unthrottled operation of a diesel that reduces pumping losses and helps
give good mileage.
turbofreak
retired engineer from GM racing programs
amount of WOT. I have 3500 miles on my GXP with same motor and get
32 mpg on hwy and even with a fair amount of town driving and hotrodding
i almost never see less than 25-27 average. HHR will not be as good
because car was 300 # more but still I think you will be happy with
the mileage. I have a DashHawk and have done datalogging on air/fuel
and because of the direct injection and the in cylinder cooling that comes from injecting fuel straight into the cylinder, the engine runs lean much more
than a port fuel injected engine. Because of electronic throttle and the way it
is calibrated, the engine acts 'diesel like" in the way it is able to mimic the
unthrottled operation of a diesel that reduces pumping losses and helps
give good mileage.
turbofreak
retired engineer from GM racing programs
Senior Member
Joined: 11-27-2007
Posts: 1,115
From: Austin, Texas
Senior Member
Joined: 07-31-2007
Posts: 101
From: MI
[
) and am curious about the best break in procedure. For a non-turbo motor, it used to be that it was good idea to use WOT occasionally to help seat the rings, but wondering if that might risk excessive blowby with a turbo, I have also heard that motors these days have better cylinder finish and don't need much time to seat the rings. Also, how does synthetic oil play into this whole break-in, as it used to be that you weren't supposed to use synthetic until the motor was "broken in". Thanks in advance for any helpful hints.[/QUOTE]
When I got my GXP, I asked an engineer in Powertrain about proper breakin
and was told with the GXP that you need to breakin the diff more than the
engine. With the cylinder finishing procedures they have these days, there is not much that one needs to do. I was told you might get rear end whine
if you did not let the rear end breakin for about 500 miles with mimimal wot.
That said, the HHR has a transaxle which may be different than the diff in
a rear wheel drive car like GXP. I will ask about transaxle.
I am going to be fairly easy on it for 100 miles or so and vary speeds and
do an occasional complete lift on throttle at speed for a few sec to
allow high vacuum to pull oil past rings to help sealing. It may not be
necessary but can't hurt.
turbofreak
) and am curious about the best break in procedure. For a non-turbo motor, it used to be that it was good idea to use WOT occasionally to help seat the rings, but wondering if that might risk excessive blowby with a turbo, I have also heard that motors these days have better cylinder finish and don't need much time to seat the rings. Also, how does synthetic oil play into this whole break-in, as it used to be that you weren't supposed to use synthetic until the motor was "broken in". Thanks in advance for any helpful hints.[/QUOTE]
When I got my GXP, I asked an engineer in Powertrain about proper breakin
and was told with the GXP that you need to breakin the diff more than the
engine. With the cylinder finishing procedures they have these days, there is not much that one needs to do. I was told you might get rear end whine
if you did not let the rear end breakin for about 500 miles with mimimal wot.
That said, the HHR has a transaxle which may be different than the diff in
a rear wheel drive car like GXP. I will ask about transaxle.
I am going to be fairly easy on it for 100 miles or so and vary speeds and
do an occasional complete lift on throttle at speed for a few sec to
allow high vacuum to pull oil past rings to help sealing. It may not be
necessary but can't hurt.
turbofreak
Thread
Thread Starter
Forum
Replies
Last Post