My LT1 is getting close to 200K and it's starting to show. Gas milage on the highway is at 23 down from 25, there are ticking sounds, there are small leaks here and there, and I was down a quart at my last oil change. These are all perfect excuses to rebuild and I want to plan it out now so I'm not stuck researching when I could be taking action should it take a dump on me. I'd like to have a plan ready to go.

I'm not looking for anything crazy, this is my daily driver. However, since I'd already have the engine apart, might as well upgrade. My main concern is maintaining the fuel effieciency since I drive this thing A LOT. Around 25 mpg on the freeway would be great. I'd like to get as much power as possible while doing that. 400 rwhp would be sweet but I wouldn't sweat 389 or anything. All the threads I've found around here talk about throwing in a head and cam combo and/or jacking up the displacement and calling it good. They're probably barely hanging on to double digit gas milage though. I'm sure cheap easy power was all they wanted.

What is the main determining factor in fuel economy as far as the engine, or main factors?

I'm not planning on nitrous or forced induction down the line and I'd like to keep her around at least for another 15 years or until the world's oil supply dries up Considering how old and extensively used this engine is, I'll probably end up replacing most of it.

How can I build a 400 rwhp LT1 that gets 25 mpg on the highway?

 

If I were you I would look into a heads and cam package from Lloyd Elliot or Advanced Induction. They are both proven performers and I'm sure they will be willing to come up with something in the power range you desire.
As far as your shortblock either have yours rebuilt or buy a short block from GM.

 

With a six speed as long as your dont change the gears you can probably squeze mid to low 20mpgs as long as you keep your foot out of it. I agree with getting a custom cam and head package from AI or Lloyd Elliot. A cam with a little bit of a tight LSA would give you better gas and sound more like stock

 

Thanks for bringing up Lloyd Elliot and AI, they had some good stuff on their web sites. Now I have somewhere to start for the H/C combo.

What is LSA?

As far as the rebuild, would they be able to do a full rebuild for me or just heads and cam? I found through some searching on this site that Summit sells a rebuild kit, pretty inexpensive, seems too good to be true. http://store.summitracing.com/partde...&view=1&N=700+

I guess gaskets and bearings are what suffer the worst from time and use, should've been obvious but it didn't cross my mind.

It looks like the big items are crank, connecting rods, pistons, cam shaft, timing set, oil pump, heads, intake manifold, and then the valve train which I havn't even started looking at yet as far as what it's made up of. Gets a little overwhelming, probably gonna get a book about this thing and start reading...

 

if you want, you could always get a supercharger setup too.

If you go this route, rebuild it with h-beam rods, forged crank, and good forged pistons, some ported heads, and you can use a stock cam. Run 5-6 PSI, enjoy your 400HP without a radical cam, and get pretty decent gas mileage.


Otherwise, i would recommend getting ported heads, something like a crane 227 since its your DD. You can get into the 11's with them, and they have gobs of low end, making them fun for DD cars.

Think of where you spend most of your time driving....lower RPMs, your going to want something that has power down low in order to have the fun on the streets you want.

Just my .02