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LS 3.5 V6 Vs LS 4.6 V8

 
Old 07-05-19, 01:41 PM
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Richardgil
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Default LS 3.5 V6 Vs LS 4.6 V8

It is my opinion that there is virtually no difference in gas mileage in real world driving between the two engines. I think in EPA testing the turbo charged engines do better, I cannot tell you why. I am interested in the opinions of others on this.
Very disappointed that the V8 is no longer available in the LS.
Also interested to hear from anyone who has driven both for a comparison.
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Old 07-05-19, 01:58 PM
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FWIW, I am a V8 guy.
Twin turbo twin trouble
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Old 07-05-19, 02:41 PM
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The twin turbo 3.5L V6 actually has much better torque then the 1UR-FSE V8 below 4000RPM, but real-world fuel economy when loaded is worse because turbocharged engines use extra fuel enrichment to protect components (exhaust valves, cylinder heads, turbine impellers) from excessive temperatures. Where the V8 can run 11-12:1 Air-fuel ratio under load, the turbo engine has to dip down to 9:1. Ford's Ecoboost and the GM 2.7T truck engine also do this, and have worse fuel economy when towing than their NA engine counterparts. Hard acceleration is similar to towing, so when you drive an LS500 hard it will burn more fuel than the LS460.
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Old 07-05-19, 02:46 PM
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Originally Posted by Richardgil View Post
It is my opinion that there is virtually no difference in gas mileage in real world driving between the two engines. I think in EPA testing the turbo charged engines do better, I cannot tell you why. I am interested in the opinions of others on this.
Very disappointed that the V8 is no longer available in the LS.
Also interested to hear from anyone who has driven both for a comparison.
Turbocharged engines rely heavily on the foot of the driver for the gas mileage. Because they typically make far more torque than a naturally-aspirated V8 at the same RPM in a TT configuration, driving it at a sane pace and keeping out of the throttle can yield better gas mileage. But, the minute youre in the throttle more, your engine has more air to deal with and requires more fuel. So, then you kill your gas mileage. People driving highway will often seen the benefits of the TTV6 if they just cruise, or if they leisurely accelerate in town.

The TTV8 Audi gets better gas mileage than the 4.2L V8, despite making more power, but that number can dip dramatically to 2/3 of the gas mileage of a 4.2L (or less) if you decide to be more rowdy with the throttle.
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Old 07-07-19, 01:15 PM
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those 4.6s are in the tundras
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Old 07-10-19, 08:42 AM
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I was a staunch V8 guy, and to some respect...still am. That said, my 3.5 twin turbo in my SHO is killer. I still miss the V8 rumble, but the torque in my SHO's V6 is intoxicating. AND max torque comes in at only 1500 RPM...basically, just off-idle lol.... which is ridiculous. So far, reliability is perfect, but it's only been 16k miles. From what I've been reading, reliability is stellar in the Ford engine, so I would suspect Lexus to be even more so.
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Old 07-10-19, 02:30 PM
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Agreed with the above posts; TT engines do better in the EPA testing (which simulates driving like grandmama) but IRL the TT engines get pushed harder to keep up and more fuel is required to help keep temperatures down inside the combustion chambers. Honestly with the additional maintenance these engines require It's kind of a scam; i suspect the gross environmental impact is similar to an NA V8.

The UR is a peaky engine; i can remember driving a 460 and thinking for all the extra HP and torque it doesn't feel any stronger than my 430 around town. You really had to cane it and then it took off like a rocket. IMHO the TT V6 and the 4.6 feel a little soft off the line; once the boost comes on the TT feels stronger at low RPM. The 600 however is a different beast...
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Old 07-10-19, 11:53 PM
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Originally Posted by jainla View Post

The UR is a peaky engine; i can remember driving a 460 and thinking for all the extra HP and torque it doesn't feel any stronger than my 430 around town. You really had to cane it and then it took off like a rocket. IMHO the TT V6 and the 4.6 feel a little soft off the line; once the boost comes on the TT feels stronger at low RPM. The 600 however is a different beast...
460s I've driven actually felt weaker down low. Too many gears exacerbates it. Don't get me wrong though--wind the 4.6 out and a 430 will be eating dust. But the 4.3 old school V8 was the best LS motor....not trying to bait, just my humble opinion.
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Old 07-11-19, 05:22 AM
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I moved to an LS500 in November from an LS460L. Here's my experience wrt mileage:

1. LS500 - lower mileage in city driving compared to LS460L 16.5 vs 17.7 driving on the same roads and routes.
2. LS500 - 36.5 MPG on highway at a steady 75 mph. I got about 29.5 on an LS460L on the same highway at the same speeds.
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Old 07-11-19, 07:05 PM
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Originally Posted by AJT123 View Post
460s I've driven actually felt weaker down low. Too many gears exacerbates it. Don't get me wrong though--wind the 4.6 out and a 430 will be eating dust. But the 4.3 old school V8 was the best LS motor....not trying to bait, just my humble opinion.
I would agree with that...
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Old 07-11-19, 07:37 PM
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The smooth operating 4.3 torque peaked at [email protected] rpm. Lowish for a small V8. The 4.6 does [email protected] rpm. The gearing makes you have to wind out the 1UR a bit. Seems that other F car owners also mention lack of torque down low and the need to get the revs up in the 5.0.

Having run full mandrel bent cat backs (deleted secondarys) on both motors Id say the 1UR responds so much better.
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Old 07-11-19, 07:52 PM
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Making this heavy 4 door luxury vehicle with a sport or F package is like lipstick on a pig....................WHY?

To me .................and only ME !

Is just stupid!

Let me also add putting 22 inch no sidewall tires on a 2 ton vehicle vehicle, silly!

JMHO.

Don't try to make it into a vehicle it was never intended to be!
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Old 07-11-19, 07:55 PM
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Oh by the way......................do what you want I approve, it's a free country............well it used to be!
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Old 07-11-19, 07:58 PM
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The same reasons why German flagships have those packages. Not once was 22” rims mentioned in this thread.

The F car Aisin 8 speed in any Sport or F Sport the difference maker.
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Old 07-11-19, 08:01 PM
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Originally Posted by VanCityLS4 View Post
The same reasons why German flagships have those packages. Not once was 22 rims mentioned in this thread.
Because the Germans do it means nothing!
I mentioned it!
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