Anyone heard of Acura RSX success stories?
 

I'm looking to get out of my 2006 4-Runner that seems to always get 14-18mpg this summer. I have owned many Honda's and Toyotas over the years and cannot see any reason to ditch these brands yet.

I was originally looking at the early 90's civic models CX DX VX, however in the big city that 92hp is nearly dangerous to drive. I have gotten used to the 4.0L torque in the SUV.

The base model Acura RSX (K20A3) utilizes some tricks that might make it a fuel sipper in the right hands. It has an adaptive composite intake manifold. The VTEC mechanism is similar to the VTEC-E of old days where it runs on 12 valves and then jump up to 16 valve in "VTEC" rpm range. It has the advantage also of Honda's cam phasing on the intake cam only.

I have a bit of a soft spot for the K-series motors as I built a MR2 Spyder with a K20z3 swap a few years ago. The ability to tune with Hondata is also a very nice benefit.

Anyway long story short, I was just wondering if anyone has done it or heard of decent numbers coming out of these cars? It would seem the shape of the car is a decent starting point and the mechanics fit the theory as well, with some gear ratio changes (the Final drive in 5th is a little higher in rpms than ideal). The EPA fuel ratings on them is not great but I suspect it could be under rated or possible to greatly improve it with a different gear ratio and proper tune via the Hondata system.

Thanks,

Liberty

Take a look at entries in the garage here, and on Fuelly:

EcoModder Fleet list - EcoModder.com

Acura RSX MPG - Actual MPG from 374 Acura RSX owners

It looks like in the hands of the right driver, in perfect conditions (warm air, no A/C, low speed highway cruising) you can probably expect to average upper 30's. In the hands of most drivers, upper 20's are realistic.

My guess is that much of it is from gearing; the gearboxes on these cars have notoriously short top gears. You could probably swap in the 5 speed from an Accord K24, or perhaps just use the final drive in an RSX 6 speed.

That said, I'd love to drop a K20 in my Insight. Due to the light weight and low drag, 50mpg with 200hp+ (in a sub-2000lb car) on tap is realistic.

Here is what the 2100 lbs MR2 Spyder with a K20 (200 whp) looks like
https://www.youtube.com/watch?v=rHjs7rRAM5I

I never did check fuel economy on that car but I can say city driving it was terrible and highway was decent. I had one of the shorter gear ratios from the 06 Si.

I had looked at the Accord trans, also the TSX trans had a magnesium case which is pretty cool, although I think the weight savings is minimal.

-Liberty

Looks like a stock K20Z (or equivalent), naturally aspirated, is good for about 13 seconds on the quarter mile and just under 5 seconds to 60 in an Insight with some other weight reductions.

But I digress. I consider 30mpg to be relatively poor. I'm note entirely certain why RSX's are coming out so low in the real world.

If the car could pull in the neighborhood of 40mpg and have the factory rated 160hp for some city driving get up and go when needed, I see that as the best of both worlds. I think it is entirely possible, maybe I'll have to be the one to prove it...

-Liberty

I say go for it, I've thought more than once about an RSX after I'm done with my Civic. I kind of see why people like Hondas, and the RSX is kind of all of those things taken a bit further. You can be my guinea pig :D

Keep in mind that 2002-2004 models have a lower cruising rpm than 2005-2006 if you don't think you are going to actually swap transmissions. I assume you have settled for the base model? If I was getting one I would have to get the type-s. Oh yeah, and the earlier models have 16" rims that weigh 16 pounds, the later models got 17" rims that were heavier.

I have compared the profile of the 1st gen insight to the rsx and it is really close! That made me wonder why the drag coefficients are so different, 0.25 vs 0.32. If you can make some mods to bring the rsx closer to the insight then you should see some serious drag reduction.

The short gears is what ruins my fuel economy on the TSX. I'd like to throw an RSX final in to drop the RPMs a bit. I imagine gearing is the #1 challenge to your RSX. I actually get better fuel economy in gridlock stop and go rush hour traffic than steady cruising at 72 MPH.

My previous car was a Del Sol with a B18B and B16A transmission. At 70mph it was something like 4200rpm? I got around 30mpg cruising at those speeds, and improving aero didn't do jack. Pulse and glide helped tremendously. I expect it was nearly all drivetrian losses.

What's the combination that would result in the tallest gearing for a K series? None of the calculators I've looked at include transmissions other than those in the RSX and -S.

It looks like the 08+ Accord is the best OEM solution

https://www.hybrid-racing.com/blogs/...smission-guide

The Accords are EPA rated at 31mpg with the larger 2.4L so hopefully that combo works out well on the 2.0L

I also found a listing on eBay for a 4.1 FD set which would probably make a nice difference in combination with that transmission.

When I had the MR2 K20, the used motor I bought came with a trans where a kid was drag racing and broke 3 teeth off the FD gear. So I have some direct experience working on these transmissions. Very easy and simple to break down much like the B-Series trans.

-Liberty