Topic: 1 year on the replacement motor

[Rogue]

It's now been about a year since we replaced the motor in GXPsy. That was a pretty painful experience, but we've gotten over that part of it. We purchased a complete crate unit from ZZPerformance, and had a few install issues to resolve. Now we're glad we did. Oil pan interference, heater hose/cylinder head configuration, etc. The end result has been worth it. Our local GM dealer did the work for us, and in the process identified the engine as one of a special build for the high performance HHR. I do not know what the exact differences are internally, however the power is obviously higher than the original LNF (with GMPP tune) and the average fuel economy is at least 2 mpg better than before. Woohoo. More power, less fuel. The Mrs just loves blowing the unsuspecting rice rockets into the weeds!

[Johnny_gxp]

Glad to hear it! I don't get to surprise people anymore  my car is too flashy now. Also, I do believe the HHR SS still made 260/260 unless of course it was just another GM hush hush like the old LS1 trams am. (States 325hp made 350ish)

[Sly Bob]

Glad the swap worked out well. If I lost mine I do know which way I'd turn. Maybe a V8 swap but I don't know...

[Rogue]

I don't know what the difference is either, but it obviously makes a lot more power, the torque curve is fatter, and the fuel economy is higher. A total win for us. If anyone has any insight kindly share it.

[JesseB]

Sounds to me like you ordered the LDK long block from them?

[Rogue]

I believe that is correct. Then we swapped out the LNF cylinder head and oil pan.

[Sol Asylum]

The noticeable change in performance could be due to the decline in performance of the old engine before it died or the fact that the old engine had a problem from the start.

[Rogue]

We have considered that. But, don't believe that to be the case based on performance comparisons to my GXP.

[TomatoSoup]

The only difference I could think of would be internal friction.  That could increase mileage, but I wouldn't think it would increase power on a turbo car (presupposing the same turbo and tune).

[roxer]

Think I read where the LDK produces about 10 more hp than the LNF.

[Rogue]

I have heard some rumors (do not recall where) that the LDK compression is a bit higher. However, my first instinct was to think it might be a different cam profile. This motor seems to be more friendly to the automatic transmission.

Or, maybe it's all just our imagination.

[Johnny_gxp]

I read

LDK: 9.3:1, higher compression Pistons.
LNF: 9.2:1, and our normal piston head

That would be your extra 10 right there. But with that slight increase in compression to boost: that's a sure fire way to increase your numbers throughout the torque curve.

[Rogue]

Higher compression pistons would most definitely produce better power, torque, and economy figures. Especially coupled with the boost effects of a turbo.

[Rogue]

Johnny_gxp - That's interesting info. Where did you source it?