5th Gear Swap from NSN - Anyone Tried This?
- Thread starter MyZmZm
- Start date
rx7mazda said:
You lower the side of the transmisison and remove the black cap and then swap out fifth gear... so you are very much removing and changing part of the transmission.
As far as the work harder etc.. that's exactly what I was talking about Andrea regarding if you go to low.. it's hard to explain but it shaped like a parabola... as your rpm's go down for a given speed load for the motor does go up and that can require more gas... but a small change like we are doing drops rpm's enough while keeping the load from going up too much such that the car will get better gas mileage.. roughly 1-2 mpg better...
spacemonkey
Member
- :
- Mazdaslow
if its easy enought then I will surely go for it! Its a damn good price and im all aobu tgetting btter gas milage. I loged an average of 30 mpg on my trip from Orlando to tampa...and the car was a blast to drive. Even better if it can get more milage on the highway!
it doesnt affect 1st gear and lower your RPMs in OD...why not?
im going to wait on the instructions to be released.
it doesnt affect 1st gear and lower your RPMs in OD...why not?
im going to wait on the instructions to be released.
How much highway/fifth gear driving do you do, and how quickly would you say it paid for itself? Is this a 'driveway' install with jackstands and basic tools, or is it better done by a shop?Mental Addiction said:
With the way gas prices are going these days, every little bit does help. For someone who does mostly city driving, with occasional long-distance (ie 1-2 days one way) trips on the highway, would this still offset the cost of the parts and install in the forseeable future? Like spacemonkey, I'd love to have a bit more info on exactly what is involved with installation - and some real world experience and feedback would be great - before making a decision.TurfBurn said:
And Steve - thanks so much for even replying to this thread while you're on the road. (first) Just another example why you're such a great vendor and appreciated member of this site!
You need an impact wrench or access to one... that's about it... as far as being a driveway install... that's somewhat debatable... it could be done as such in theory, but it is a relatively complicated bit and you can't lose any pieces... but the instructions will explain all that!
Later,
Steve
Later,
Steve
Yeah... we are working on it. One of the other owners did it to his car as the test bed... and he has all the pictures etc... but he just moved from California back to the Midwest, so he's in the middle of that mess and I haven't gotten all the pictures and the info for the write-up yet.. but it will get done probably around Christmas week (long time away I know... sorry!) and it'll be hosted on our website, and posted into this and other threads as well...
The short version is this though:
Jack car up
Drain transmission
Remove battery etc and release driver side engine mount
Remove driver side wheel.
10mm wrench to pull bolts to get black cap off...
use chisel/screwdriver to unbend lock tabs on transmission shaft nuts
using extension and impact wrench and 23mm socket to remove nuts.
slide gears off shaft and replace with new gears. Put on new nuts provided, put cap back on.
Refill trans, replace engine mount and wheel. Let it down... try it out.
It really isn't a lot more complex than that. The hardest part is lowering the engine enough to get access to that cap.. but it is quite doable and rather simple... and you can get an impact wrench for 30 bucks from www.harborfreight.com.. I actually have and use one from there and use it all the time and actually love it!
The short version is this though:
Jack car up
Drain transmission
Remove battery etc and release driver side engine mount
Remove driver side wheel.
10mm wrench to pull bolts to get black cap off...
use chisel/screwdriver to unbend lock tabs on transmission shaft nuts
using extension and impact wrench and 23mm socket to remove nuts.
slide gears off shaft and replace with new gears. Put on new nuts provided, put cap back on.
Refill trans, replace engine mount and wheel. Let it down... try it out.
It really isn't a lot more complex than that. The hardest part is lowering the engine enough to get access to that cap.. but it is quite doable and rather simple... and you can get an impact wrench for 30 bucks from www.harborfreight.com.. I actually have and use one from there and use it all the time and actually love it!
Not too thread-jack, but I have a "load" question and this seems to be a gathering of intelligence on the gearing/etc subject.
Which is more efficient as far as mileage and cruising?
A - Low % of throttle opening @ higher RPM's
- or -
B - Higher % of throttle opening @ lower RPM's
Which is more efficient as far as mileage and cruising?
A - Low % of throttle opening @ higher RPM's
- or -
B - Higher % of throttle opening @ lower RPM's
BradC said:
Depends on your fuel curve basically.. I'd have to pull some of my fuel maps off the Microtech to give you data... but here is the rough break down...
At about 25inhg to 20inhg vacuum, the fuel requirement stays nearly linear... roughly a 1.45 ms injector opening time with 550cc injectors (my car). Which is in part due to my setup and injector size.. it's a little different with a different injector firing pattern and smaller injectors.. but anyway... so the fuel requirement stays relatively flat at very low vaccums and then as load increases, fuel requirement goes up at a relatively linear rate... however, more fuel is required at rpm's that are closer to volumetric peak efficiency (our volumetric peak efficiency is around 4000-4500 rpm's). So that means that even if you were say holding 14 inHg (normal for highway cruising) each injector open time is BIGGER at 4,000-4,500 rpm's than it is at 3,000-3,500 rpm's.. so not only are you turning more rpm's (more time per minute that the injectors open) but you are also holding the injector open longer... so you use a considerable bit more fuel there. Roughly speaking our motor uses fuel like a shifted bell curve... it ramps up somewhat linearly toward 4,000 to 4,500 rpm's, and then begins to fall off rather shaprly after about 5,200 rpm's... That's all out of the scope though of discussing highway cruising...
So, on our car when comparing 3,000 rpm's versus 3,500 rpm's (the gear difference essentially) the car will use less fuel per injection at 3,000 rpm's than 3,500 rpm's because of the volumetric efficieny, and will also use less fuel because of less injections per minute. Now adding the gear increases the load and your fuel consumption will go up a little bit because of the higher load... BUT that is roughly negated by the volumetric efficiency difference... so now you are using at a higher load at 3,000 rpm's roughly the same amount of injector open time as you would at a LOWER load at 3,500 rpm's... so the load is a wash and you arrive at your savings in gas because of the lower rpm's...
That answer that?
Then as far as the "cost savings" of putting in the gear... Average american drives about 14,000 miles a year... Assuming a base gase mileage of 26 mpg that requires 538.5 gallons at a mean price of ~2.20 it costs $1184.61. Now do the same math but at 28 mpg (boost of 2 mpg from gear) it requires 500 gallons, or 38.5 less.. which is a savings of 85 dollars. But that is approximate and it could be better or worse... Depends on how much you use 5th gear.. how many miles you drive etc... but roughly speaking I'd say 2 years would "pay for" the gear. Keep in mind that it will also lessen cabin engine noise and so forth... so it's a good mod... especially for those that have exhausts that like to buzz around highway cruising speed rpm's.
Thanks!
Steve
^What he said. But yeah, good info. Very interested in this, but would def. like to see pictures and a complete write-up, as well as feedback from the guy who did this. Can't do anything until spring at least (damn winter weather), so I'm not in a rush.
But yeah, good info. Very interested in this, but would def. like to see pictures and a complete write-up, as well as feedback from the guy who did this. Can't do anything until spring at least (damn winter weather), so I'm not in a rush.a223818 said:
It shouldn't be for highway cruising in general... but uphill or windy days may cut the gas mileage gains down because you won't have the available torque at the given load to be able to compensate....so you just would get roughly equivalent gas mileage most likely rather than the improvement.
jimmysuite
Member
- :
- 2003 Mazda Protege5
I vant one! I vant one! how much? I have been looking for something like this for a while.
jimmysuite
Member
- :
- 2003 Mazda Protege5
My goal is a fast fuel efficient mp5!!
