40+ mpg ave doable from a 1st gen Miata?

[bhazard]

Plenty of lower power B-series engines that'll bolt to the stock trans. 1.3 and 1.6 SOHC versions are plentiful. If you want you can even try to find the 1.1L version to import. Those weren't sold here.


I think gearing and aero are bigger issues though.

[fujioko]

I built two + 40 MPG Miata's.

The first one had a three cylinder geo metro engine. The G10 engine didn't have a lot of low end power.

My second Miata has a B3 1300 engine from a Festiva, This is a great engine and it delivers more than enough torque on the low end. The B3 version is an excellent overall performer for daily driving. The only negative is the B3 falls flat on its face above 4200 RPM.

An untested alternative to a motor swap would be...

Start out with a 1.6 first gen Miata. Swap in camshafts from an automatic equipped Miata. This will bump the TQ up and cut the HP a little.

Next, swap in a RX-7 fifth gear set.

Finally swap out the 4.30 rear axle with a 3.90.

I have no idea what to expect with that combo but it should be a good start.

[cosmick]

Miatas are supposed to be fun, so swap in an aluminum-block version of GM's '01-up 5.3L V8, swap in the 4.8L crank, rods, and pistons, add a '98-'02 Z28's T56, gear it to 1400 RPM at 65 MPH, add a 66-mm-or-larger turbo for the muffling, ( STS rear-turbo ) keep the boost to 5.6 psi for emissions-legality, and that should do 35 MPG with well over 300 RWHP. Then order the biggest brake kit available, then thewidest wheels that fit, choose tires with tread widths the exact same as the wheel widths ( probably wider fit on the rear ).
That'll make it a really fun car with really good MPG.

[spacemanspif]

Hey Cap, why not invest some money into the Saturn's suspension and keep it instead of getting into a new car with new problems? Springs and sway bars should make it corner much better and some light weight wheels and sticky tires should get it cornering even better. Is yours a single or dual cam car? I was getting 44mpg with my 95 DOHC with a SOHC trans and cruise set on 60mph.

[Cd]

Originally Posted by CigaR007

An interesting take on the Miata's Aerodynamics.

https://hanchagroup.wordpress.com/tag/miata/

So that splitter knocked off two counts of drag ? Impressive !

[CAPTAIN CHAOS]

Boy, lots of replies here!
I'll try to address some questions/comments.

In the Saturn I average about 40-41 for the better 9-10mo out of the year (cars bone stock). Winter drops me down to 37-ish. Regardless of how good this car is though no amount of lowering/modding is going to make it 'fun'. It's still going to be a FWD car (the most horrid of drive configurations IMHO), with a spongy chassis, numb feel and not a sporting bolt in the whole of its construction. It's a great car and I have tremendous respect for what Saturn did when they built it but it bores me to tears.

I figured aero and ridiculously short gearing would hurt me on the Miata. I considered a 3.64 R&P swap to be pretty much mandatory. If I could get even NEAR 40mpg (even 36-37mpg) it would be worth it, to me. I was really just wondering what a carefully driven Miata could accomplish as it seems like my best bet for that all-elusive 'fun/milage' ratio that I long for.

[MetroMPG]

You need a garage entry: so people in this thread (and every other post you make) know what year/kind of Saturn you're driving.

I was going to look up how you're doing vs. its highway EPA rating.

[CAPTAIN CHAOS]

Originally Posted by MetroMPG

You need a garage entry: so people in this thread (and every other post you make) know what year/kind of Saturn you're driving.

I was going to look up how you're doing vs. its highway EPA rating.

Sorry, I just never thought to fill that out. It's in there now.
To save you a few keystrokes; it's a 2002 Saturn SL2 manual trans. EPA rating on it is 23/34-27comb., which is utter BS, I'm not sure how I could even get it THAT low! Lol!
I average just right at 40mpg w/ it on my 80mi round-trip, 80/20 hwy, commute.

[MetroMPG]

OK, so you're 18% above the Saturn's highway EPA rating in your mostly highway/country roads commute.

Ignoring the question of how accurate the ratings are for each car...

A '90 Miata is rated 28 mpg US highway. So assuming you could also beat that by 18% with the same driving style on the same route, you'd be looking at 33 mpg.

[spacemanspif]

Taller gears in the Mitata could turn the zippy chassis into a boring Saturn real quick. Those cars are geared low to aid the weak engine and make it "feel" stronger. Loading the engine with taller gears could turn it into a dog real quick. It may hold it's own on the highway but it might not be able to get out of it's own way at a red light which might kill it for the driving experience you are looking for. Maybe a Miata would be a better 2nd car than primary?