PDA

View Full Version : A economic swap (mpg)?



superhatch
05-23-2008, 11:12 AM
So I've been trying my best to keep my speeds down, and drive like a sissy unless I'm going to the track or Auto-X. I've been seriously considering a K24 swap, but now I'm really curious if I can pull even low 30mpg with a stock K24. Based on daily driving and fuel efficiency, I'm guessing the K20's are going to net me better mileage as a daily driver by probably 5+mpg. I know it's not usually a consideration, but as a daily driver I want to keep the best of both worlds.

What are you getting for an average mpg with your k24 swap?

davisj3537
05-23-2008, 11:22 AM
On mileage you are fucked either way. To get the best mileage you just drop your tranny and put in a 4.0 final drive and a tsx 6th gear. You will see near 40mpg on the highway!!!! I got around 31mpg with my k24 but I had a 6spd and a tsx 6th gear.

superhatch
05-23-2008, 11:32 AM
Well, I think I want to stay away from changing the final drives of any of the 6 speeds. I haven't looked into gear ratios yet. The txs has the best 6th gear ratio? Is there somewhere that lists K series tranny ratios? (checking search now).

superhatch
05-23-2008, 11:42 AM
Found this on a K20a sales thread on h-t. Didn't find anything searching here.

http://img.photobucket.com/albums/v504/MJ23FE/Tranny%20Gear%20Calculations/K-SeriesTransmissionTablev3-28-08re.jpg

davisj3537
05-23-2008, 01:12 PM
The tsx and the new si's have the same 6th gear:mwink:

powdbyrice
05-23-2008, 01:23 PM
and the rsx-s 6th is the same as our 5th, so dont swap in that tranny!

as stated above, just add the tsx 6th to the A3 tranny. there is a thread about it too.

wil524
05-23-2008, 01:52 PM
You can try the RSX base tranny. The drive ratio is 4.3 versus our 4.7, should drop you to less than 3k rpms cruising at 65 mph.

lldiesel386ll
05-23-2008, 05:30 PM
add a tsx 6th to that rsx base and you can potentially be cruising at around 3300 rpms at 80:mtongue: (that is right, right?)
granted you would hopefully have the power to avoid being bogged down at that speed

talonXracer
05-23-2008, 05:50 PM
A K24 block of your choice paired with a base RSX tranny with a TSX 6th and LSD added. The more powerfull engine carries the longer gearing well.

cow
05-23-2008, 06:08 PM
I wonder what the ratio of money saved by better gas mileage with the TSX sixth & 4.0 final drive is vs the amount of money spent saved by not doing the installation & cost of parts.

There was a study done a few years back showing Prius owners had to drive something like 40k miles per year to offset the extra miles per gallon the Prius got versus a Toyota Corolla that has an MSRP of about 10k fewer dollars.

Just a thought I had. Comments?

talonXracer
05-23-2008, 06:16 PM
Fuel is not going to get any cheaper. Personally my next engine will be a K24 build with a 14:1cr to run on E85. Gotta do something to account for future shortages of dino based fuels.

superhatch
05-24-2008, 08:50 AM
Just a thought I had. Comments?

I think that's a valid point. I think you have to do a tranny gearing mod with the intention of driving the car for a handful of years to get the benefit. But if you get a 6 speed with your swap (assuming you do an A or an A2) I think the benefit of changing out the 6th gear using your own labor would be realized pretty quickly.

cow
05-24-2008, 08:58 AM
Being able to do one's own work is wonderful, but for most, that's not really an option.

Again, I'm just kicking around thoughts in my head.

superhatch
05-25-2008, 10:21 AM
Does anyone know the going rate for a TSX 6th gear from Acura? I've never done any tranny work, but I figure this would be as good a time as any :)

v1c10us
05-25-2008, 11:18 AM
I wonder what the ratio of money saved by better gas mileage with the TSX sixth & 4.0 final drive is vs the amount of money spent saved by not doing the installation & cost of parts.

There was a study done a few years back showing Prius owners had to drive something like 40k miles per year to offset the extra miles per gallon the Prius got versus a Toyota Corolla that has an MSRP of about 10k fewer dollars.

Just a thought I had. Comments?

you'd have to know MPG of each, lets assume you get 25 mpg highway as it is
and 35 freeway after the tsx 6th and 4.0 final drive
if you drove 15k miles a year at 25mpg you'd use 600 gallons of gas, at 4.00 a gallon thats 2400 bucks.
then you get up to 35 and now thats only 428 gallons, or 1712 bucks.

edit: cow; that avatar looks like a broccoli cause the mushroom cloud has such a fat stalk. har har har