I have been having big problems with my L98 for a while now. In comparison with other L98 drivers, it's obvious I have serious problems with my engine. Now, while it still runs to my satisfaction, and I have to get the valve seals replaced in order to eliminate the blue smoke at startup problem, I've been debating for a while whether or not I should say "aw, screw it" and save money for a new engine.

After 18 months of tracking fuel consumption in my L98, here's the results.

L98:
MPG (Highway): 17.5 MPG
MPG (City): 12.9 MPG
MPG (Combined): 14.2 MPG

Mileage: 88,746.

I've given it tune-ups every 6 months, changed the oil (using Mobil 1) every 3 months, and done every other scheduled maintenance on time, I can't figure out for the life of me what else I can do. Other L98 drivers have said that they average around 18-20 MPG combined. The L98 has also never seen a race track in the two years I've had it.

I've read up on the LT1 engine itself; it looks promising: providing more opportunities to increase power in addition to increasing fuel efficiency.

Some figures I've found on LT1 fuel economy:

LT1:
MPG (Highway): 26 MPG
MPG (City): 17 MPG
MPG (Combined): 20 MPG

Or am I better off rebuilding the engine? It seems kind of costly though...I was quoted at ~$2,000.

I figure, hell, if I'm going to spend that much, why not just buy another engine? Unfortunately, this car's my daily driver, and I'm not very skilled at car mechanics, so I can't do the work myself, so I know I'll most likely end up paying an arm and a leg for the labor.

My ultimate goal is to have a daily driver with a good amount of power that I can easily upgrade in the future without spending outrageous amounts of money on. With this in mind, would an LT1 swap be better, or should I just pay someone to rebuild the L98?

Yes, yes, I know if I want better fuel mileage, get an econobox...but the trouble is, they're all too small! :/

Anyone have any ideas?

 

Well, before you go through all that trouble and expence you must know what cond. your eng. is in. Find someone (or a shop) that you can trust and have them do a compression or a cyl. leak-down test. If your testing of the eng. confirms in fact that the eng. is ok have the valve guide seals replaced. When the int. valve opens it will draw oil and air past the bad valve guide seals. This could lean out the A/F mixture and cause the computer to richen up the mixture. And that oil thats going by the seals (int. & exh.) is not doing the Oxy/Sensor any good. Have you ever replaced the O2 sensor? Anyhow go slow and take it one step at a time.

Auggie

 

Thanks for the tips, I'll try them out and see if they give me some more results. I'll see if I can get the shop to get the O2 sensor changed out at my next oil change.