What the Mazda RX-8 should have been (new autocross car build)

[John V]

Sadly, no. I was supposed to go up to get it on Saturday but the guy let me know Friday evening that someone beat me to it.

[clyde]

Originally Posted by John V

unfortunately the fuel economy is so abysmal that they're just not practical as a day-to-day car

My notes indicate:

28,339 miles on 1,661 gallons = 17.06 MPG

"It got decent mileage on the road (we averaged about 22-23mpg on the road). It was comfortable and not fatiguing to do that kind of driving. It would have been nice to have more torque in daily driving, but it hardly ever presented a real problem. Daily driving mileage was abysmal, though (more than a handful of tanks under 11mpg and 13.5 being typical)."

A number of those tanks were largely short distance, low speed stop and go (with a lot more stop than go).

Compared to what I'm driving today, those numbers don't look too horrible. At least not until you consider that what I'm driving today weighs about 900 pounds more (3755 to 2888), makes about twice the power, three times the torque, and rides on much wider and sticker tires.

[John V]

That's just it. If I'm going to get mileage that bad, it had better have a V8 powerband.

Keisler just announced an update to his LFX swap kit that makes some serious improvements. I may need to really think about that.

[John V]

[JST]

Originally Posted by John V

Oh, snap.

[JST]

Here’s sort of the opposite of what you did:

https://twitter.com/midnightdorifto/...N3lTKyKETwjI2w

[Biggins]

Yikes, sorry to see this JV! Good luck with the next steps.

[John V]

Long story short, I ended up getting replacement axles the night before I had to leave for the NJ Pro. I got the car back together and on the trailer and it performed flawlessly during competition...

... then I put a hole in the side of the block during the first round of the challenge. I'm not entirely sure why, but it dropped an exhaust valve in cylinder #3 which destroyed pretty much everything in the engine. It even took out the baffling in my oil pan, so that'll be fun to reconstruct.



So I'm pretty much dead in the water until I can build a new engine. Slightly different formula this time

2.5L block - same as before. 89mm bore
2.3L forged crank with 94mm stroke from an Ecoboost - replaces 2.5L cast crank (100mm stroke).
Billet connecting rods, about 10mm longer than before for better geometry
10.5:1 forged pistons
EcoBoost sodium-filled exhaust valves
EcoBoost oil pump

This will give me a 2,344cc engine (vs 2,488 from the last one) but it should be much happier at high RPM and it'll tolerate even more boost, so it should make the same or more power and have a higher RPM ceiling. It might make a touch less torque at 3,500 RPM but it was already traction-limited there, so no loss.

[Nick M3]

ouch.

[lip277]

Well - if you're going to go down, might as well make it count! (as my mom used to say).

Nuts... Sounds (and looks) like a big reconstruction project. Good luck....