L48 - opportunity for good gas mileage?

[Stallion]

I'm reading an article on engine build-ups and a quick sentence is:

Speaking of fast cars and great fuel mileage, we regularly realized 26 to 27 mpg from a much-modified L48 300hp 350 in a 4,100-pound Monte Carlo.

How did they do that? I guess we can assume they are using fuel injection. But how else can you squeeze out that many mpgs? Any ideas?

 

[Tom73]

How did they do that? I guess we can assume they are using fuel injection. But how else can you squeeze out that many mpgs? Any ideas?

One word, GEARS. Yep, FI and electronic engine management will help but nothing is better than GEARS. Had a 73 L82 auto with 3.36 gears, got 13 mpg on the highway. Have a 90 L98 auto with 2.73 gears (and the o/d auto) and get 26 mpg on the highway. the slower the engine has to run the better the mileage.

tom...

 

[Stallion]

I don't think the low rear-end gear is much of an option. That ruins acceleration. I'll stick with the sub-10 mpgs.

 

[John Mcgraw]

Stallion,

With the modern versions of auto trans (700R4 or 4L60) the first gear is so low that the first gear total gear ratio is lower than a close ratio 4 speed with 4:56 gears! This makes for some incredible acceleration off the line with these transmissions, and they still have overdrive and lockup torque converters to aid fuel economy. Modern C5 Corvettes knock down MPG numbers around 30 with an automatic trans, and are still scary fast! I am building a 59 right now with a C5 engine and computer, backed by a 4L60E trans. I expect the car to run into the 12-13 second area and knock down around 28-30 MPG.

http://www.villagephotos.com/pubbrowse.asp?selected=864857

Regards, John McGraw

 

[Stallion]

:eek John, that is quite the beautiful project you have going there. I loved the pictures. First off, where did you get that tube frame? A stock '59 body will just bolt right up to that no problem? That's awesome. I would love to do that when I get a little more money. I imagine that project is going to cost a couple of shiny pennies.

 

[John Mcgraw]

Stallion,

Yes, the chassis is made just for a C1. You have to cut out a little of the spare tire well to make clearance around the rear end, but the body remains stock otherwise. The company that makes the chassis is SRIII motorsports. http://www.sriiimotorsports.com/

It has been a lot of work, but I am on the downhill side now! Here are some additonal pics.
http://www.villagephotos.com/pubgallery.asp?id_=339303

Regards, John McGraw

 

[Stallion]

Wow. That is simply amazing. Definitely a piece of art. That is beautiful. It definitely looks like you put a lot of work into it, but that is 1st class work right there. Going to be a great end product. If you have any documentation that you have written out about the build-up, I would more than love to read about it. That's something I would like to tackle when I get a couple more years and dollars under my belt.

Again, just an amazing job. Can't wait to see the final product!