I have a d16z6 swapped cx with a cx tranny. This car is pathetically slow and is getting shitty in-town gas mileage. I have picked up a DX tranny and I have done my home work and realize the gear ratio difference. My question is, Has anyone done a swap similar to this? And did you realized a huge difference in drive-ability and fuel mileage? I am sick and tired of driving this over geared monster and need some input before I do this! Thanks

 

DX tranny will be a lot better than CX. If you could grab hold of a Z6 tranny it would kick ***. I got like 40mpg with my cx tranny, i hope you're not lugging that thing.

 

I don't lug any honda, thats just foolish. I can get my hands on a ex tranny for 125 bucks but I think that the dx will be better overall. Its the g/f's car and she want's better gas milage more than anything. The only reason we swapped the z6 in was because we got a good deal on it, not to make a race car.

 

I would go with the EX tranny if you're not doing any highway driving. Its a lot funner to drive and your gas mileage depends on the way you drive mostly. With the dx/ex the difference isn't very noticable if you don't smash on it.

 

+you could trow a CX 5th and youd be good for the highway

 

this is a daily driver and sees teh highway every weekend for at least 200 miles. Thanks for the input, I think the dx will be the best way to go!

 

Do you even know the ratios?

 

DX

1ST 3.250
2ND 1.761
3RD 1.172
4TH 0.909
5TH 0.702
final 4.058
CX

1st same
2nd same
3rd 1.066
4th 0.853
5th 0.702
final 3.250

Si
1st 3.250
2nd 1.900
3rd 1.250
4th 0.909
5th 0.750
final 4.250

 

it's the final drives that end up making the big difference in gas mileage.

If your gf doesn't car just do the dx tranny.

Either way it'll be about the same.

 

I would think that the CX transmission would give the best gas mileage out of them all. I was always under the assumption that the longer the gearing, the better your mpg. Is that incorrect?

 

i would imagine to a point. i have a dx with a hf tranny and it runs like **** and bogs into every gear, just bought an si tranny, on the way!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicSpoon &raquo;</TD></TR><TR><TD CLASS="quote">I would think that the CX transmission would give the best gas mileage out of them all. I was always under the assumption that the longer the gearing, the better your mpg. Is that incorrect?</TD></TR></TABLE>

Well your sorta right. Once you get to a certian point it makes the engine work to hard in turn using more gas than it should. Right now her car strains its ***** off all the time. I can't even climb some hills on the highway in 5th gear without droping under 65mph. I believe that the vx and cx motor created its power on low end, and the ex/si was built to make power @ higher rpm's hinse why a vx motor and ex tranny don't match up very good its like the worst of both worlds when they are bolted togather. If I am wrong someone let me know.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicSpoon &raquo;</TD></TR><TR><TD CLASS="quote">I would think that the CX transmission would give the best gas mileage out of them all. I was always under the assumption that the longer the gearing, the better your mpg. Is that incorrect?</TD></TR></TABLE>

Yes youre sort of right. Think about it this way,rev to 7k in first and let go,RPMs drop quickly,do the same in 3rd,its going to slow down a lot slower,the reason people want long high gears is that they can just shift and cruise there with little gas. If its too long then the rpms will drop and youll have to give more gas when you need to find the right gear for your daily route.

 

The thing that most people don't understand about the looooong economy gearboxes is that highway driving involves A LOT more shifting than any other gearbox. Selecting the right gear for the right situation is very important to utilize those long gears. Basically you ONLY use 5th for steady level-ground or down-hill cruising. If you want to accelerate, or even go the same speed up a small hill, you have to down-shift to 4th. And if you want to pass someone or go up a steep hill, you had better drop down to third (and pray ).

From the gear & final drive numbers posted above, the CX 4th will be nearly identical to the DX 5th (CX is just slightly shorter). This means you can simply run your CX in 4th gear on the freeway to get the same results as swapping gearboxes, with the added bonus of having an extra top gear for easy cruising and going down hill...

The top gear is only to reduce rpms at steady state. If you want fuel economy, stick with the CX gearbox and adjust your driving style...

 

Ok, I see what you guys are saying. But, IMO there are ways around some of it, specifically learning exactly when you need to shift into a certain gear. I personally own a stock '94 CX, so I know how long the tranny is. But I also have learned what gear it needs to be in at a certain mph (no tach in car, so I don't go by rpms). For me I shift to 2nd at 20mph, 3rd at 33-35mph, 4th at 43-45mph, and 5th at 67mph. Any slower (even by 1 or 2 mph) and it will bog like crazy if I'm in a higher gear. But I completely agree that 5th gear is worthless unless you're on flat ground, or going over a 65 speed limit. But the rpms in 4th gear are still really low at 65mph (I'm going by noise level here), so just staying in 4th gear shouldn't effect mpg much at all (maybe 1-2 mpg I'd guess).