LS engine with best horsepower to gas mileage ratio?

[luckyusaf]

I am building a Pro Touring 66 Chevelle and wanting to put in an LS9 or LSA engine. After doing some more research there are not a lot of classics out there with these engines. I am curious as to why? Is it the cost factor? I want 600+ horsepower but honestly my main concern is fuel economy/gas mileage as this build is for my daily driver. I know the new vettes and CTS-Vs get decent mileage considering the horsepower they are pushing. To better some up my question...Which LS engine has the best horsepower to fuel economy ratio?

66 Chevelle
LS ?
Bowler 6L90E
Schwartz Performance Chassis
Moser 12-Bolt
RideTech Adjustable Coilovers
Wilwood 14" Rotors/6-Piston
Forgeline ZX3P 20x12/19x10
BF Goodrich Rubber

[Chris 68]

I'm no guru, hell I'm just a 21 year old kid but I think the big reason you don't see many of these engines in our cars is not only are they expensive, but there just isn't a lot of them around compared to the thousands of LS1s, 2s, etc. I myself am using an LS2 out of a wrecked GTO, how many wrecked ZR1s do you see on the web?

As for the gas mileage, we have the advantage with lower curb weights compared to the cars these engines were designed for, but FI engines suck up more fuel, while they won't automatically destroy your MPG, a lead foot can change that in a hurry. You're kinda forced to weigh the importance of MPGvsRWHP.

It also depends on what type of driving you typically find yourself in, the 6 speeds of today really help out our highway mileage (you can see some Z06 owners claim up to 36 mpg during conservative driving) but if your daily commute involves a lot of stop and go traffic, your MPG will suffer with any LS, even more so with boosted applications.

Personally I think 600 hp is kind of pointless in a daily driver (I wouldn't object if I could get that out of my set up though haha) with the basic bolt-ons, and a cam you can EASILY get 400 RWHP (some have even coaxed 500 without touching the heads) out of any good mannered smaller LS engine, spent ALOT less money then opting for an LS9 and still get 24+ MPG.

By the way welcome to the forum! Start a build thread so we can check out that Chevelle!

[Norm Peterson]

For a DD, I'd concentrate more on the torque curve and gearing to suit it for your needs than on HP.


Norm

[rohrt]

I think its a good question from the poster. The factory had done their best to find this balance of mpg and power but they have to contend with emmisions. What improvements might help and hurt power and mpg?