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LHU or LTG, which is better for modifying?

b4black

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2016 Regal Turbo
I've owned plenty of V6 Regals (Turbo GNs and Supercharged 3800s). I'm thinking I'd like to get a manual transmission car and I'm looking at the 2011-2017 Regals. I'm also a big fan of running E85 when I can and using HP Tuners to make changes to ECM calibrations. I've been doing my homework, but I have a few questions.

I see the LHU is a flex fuel engine, while the LTG is not. Does this make the LHU easier to modify? Do both engines use narrowband O2 sensors?

What's need to run E85 on the LTG?

And what is the difference in the 220 versus 270 HP LHU? Is it the engine calibration or is the hardware different?

Thanks!
 

Walt G

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25 miles SW of Chicago
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'12 Regal GS
The LHU is the better platform for modifying/tuning for more power. The LTG was the first generation of the engine designed for the American buyer, which means better NVH and fuel economy were the primary objectives. Just the fact that the LHU has lower compression means it can handle more boost before hitting detonation limits.

The 220 and 270 HP versions of the LHU have the same long block. Calibration is different, as is exhaust for sure (3" on LHU) and perhaps intake... jury is out on that... GS versions seem to have some different intake piping, but there is only one replacement part called out by GM... exhaust is definitely different.

The 270 hp version did not come with an ethanol sensor (and is techincally not flex-fuel capable), and the consensus is because of fuel pump capacity at 270 hp on E85. Some have run more power than that on E85 without making changes to the fueling system, but some have damaged the engine, perhaps from running lean. To be safe, you should plan on at least swapping to a camshaft that has increased stroke of the high pressure fuel pump to handle the extra volume E85 requires. The ethanol sensor can be wired into a 'GS' engine that didn't come with one, and tuned in with HP tuners.

I don't know much about the LTG.
 

ken4

Full Member
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2016 Regal Turbo Premium 2 FWD
The LTG is supposed to have larger connecting rod bearings and a stronger lower end.
 

Walt G

Full Member
817
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25 miles SW of Chicago
Buick Ownership
'12 Regal GS
The bottom end of the LTG is 'stiffer', but that was because they were going after NVH. But don't confuse 'stiff' with 'strong'. That said, neither engine is bottom-end-limited when it comes to reliable power. They are detonation limited, and the lower compression of the LHU means more boost/more power before encountering detonation. Neither engine will survive high load detonation, and there is empirical evidence that the LTG has weaker pistons (google 'LTG piston failure').

Something to consider if you're going to build a very high power LHU or LTG: since the turbo is on the other side of the block on the LTG (left side when viewed from the flywheel), if it does throw a rod it goes out the side with the turbo, which means an oil fire is much more likely on an LTG in the event of a thrown rod...
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b4black

New member
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Buick Ownership
2016 Regal Turbo
I won't be throwing rods. Just looking for something to play with, not an ultimate HP build.

It's interesting that the 270 hp LHU is not flex fuel (good to know). The information out there was misleading, but I do now see that the 2.0 Turbos are listed both ways, which must be the 270/220 or GS/non-GS differances.

Thanks for the information!
 
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