Ok I bought a '96 HX shell. I got a y7 to put in it while still looking for a y5. The y7 is now installed and about to be completely done.

My question is do I run the y7 until it gives out then put the y5 in, or should I take the y7 out and sell it and install the y5?

BTW it has an ex 5 speed, and yes I have the harnesses and ecu's to do either motor.

 

Why does this need a poll? If you know it's gonna go then to the swap. At least it will be on your terms. Do you really want to chance the Y7 blowing out on you in the middle of nowhere? Hope you have AAA or money to throw away on towing and all the inconvenience that goes with that.

 

You said you have a HX shell, then talk about EX 5 speed which is d16y8? Stick with the y7

 

Honestly it all depends on what YOU want out of the car. Since you have the y7 already in there I would just run that and keep an eye out for a y5 but maybe by then you'll settle on something totally different.

If you found an hx head you could do a mini-me since you already have the harness and ecu for it.

 

I think he meant he has that tranny.

 

yes I put an ex tranny in for the gearing they have

its just a car to drive to work. I forgot to put in the OP that I found a y5 and bought it after I had put the y7 in. just left it in to make sure it runs ok incase I want to sell it

I put it as a poll for people to vote their opinion so they wouldn't have to post a reply if they didn't want to. that is what forum polls are for. it there some HT rule on when a poll can be used?
whats going to make this y7 blow? as for towing I own trailers and an '05 dodge ram diesel. not too worried about that expense. this civic is my "save money work car" (lol till I get the need more Hp bug)

 

How far is your commute everyday? Mine is 40 miles one way 5 days a week or 390 miles a week. With a y5 in there you could easily pull that off on one tank but you have an ex tranny on there.

If it was me I'd leave the y7 in there for now but rebuild the y5 then swap it in then sell the y7.

 

its about the same 35-40 miles one way 5 days a week. the y5 has about 180k on it but still runs fine. I was thinking about rebuilding it like you said. it cost me $400 with harness and ecu. just trying to find out how much parts would run me. other than the machine work I will rebuild it myself.

 

I have both a 97 & 99 hx's the 97 has 190k and the 99 has 209k on it. I've had the 99 since november but just put it on the road last friday so haven't really been driving it long enough to check the mileage. Last time I checked the 97 I got 36-37 mpg but that was letting it warm up at least 10 min. before work each day so almost an hour's worth of idling right there so not too bad at all... however I have gotten 43 mpg out of it before.

 

It seems like a lot of work to make the swap from a Y7 to a Y5 for not that much difference in performance or gas mileage. I've never owned an HX but I've gotten 44 MPGs out of my Y7 before, and have averaged about 36 or so over the five years I've had the car, which is pretty good in my opinion. However, if you want to do it for fun or just to have the original engine, go for it!

 

Geez I didn't know the Y5 got such great gas mileage. I got around 25 in town and 34 freeway with my y7 automatic. y7 in a Del Sol got around 30 in town and 35 freeway.

How the heck are you getting 44 mpg from a y7?

 

basically just wanted to get people's thoughts on if I should run the y5 now or just run the y7 until it gives out.

 

I mean, that was my best ever, driving 75ish on flat highways with me and one passenger. Like I said, I've probably averaged 36ish over the time I've had my car, but it's varied a lot. When I put bikes on my roof I only get about 22. I get 38-42 or so on the highway, 35-38 driving in Charlotte, NC where I grew up and get about 26-27 here in Miami, but that's a combination of fatter tires and much worse traffic. Mine's also a 5 speed, which tend to do better with mileage.

 

It's not any weaker that any other Y motor.

 

not meaning its weaker. all engines will get worn out at some point regardless of its power. I'm am just asking you guys that have been driving these cars for a while vs my no expirence with them

 

I would drive the y7 until it can't go any further or starts to smoke badly and have the y5 as a backup and you'll be set for a long while with no worries.

 

it's not the engine, it's the transmission. Y5s are only useful if you shift very early like less than 2500rpm and you cruise at rpms less than that. When you pair a Y8 transmission with a Y5, the benefits are severely diminished. The transmission is what gives you the mileage which is why the HX has a final drive of 3.722 instead of 4.058 or 4.25 etc.

 

It's just a d series to another d series so not too hard... the only differences are the egr, engine harness, 5 wire o2 sensor and the ecu so if you have those couple of things you should be good. But yes the main difference is in the tranny but the hx does give you vtec-e, but if you can't an hx one there is always the vx which has a 3.250 fd or the cx/dx hatch is the next best thing after the hx. Personally I like the hx one you still get great mileage without sacrificing all the power that you loose out on with the vx and also the hx has the larger main carrier bearings that the ex has.

 

Y5!!! especially with these gas prices, even the smallest difference helps.

 

Yes according to KBB the american hx model which usually have the Y5 motor in it is very fuel efficient giving about 35-40mpg highway.. but since you already have the Y7 I say stick to it unless its seriously dying then I wouldn't risk it blowing up

 

TRANSMISSION! is the PRIMARY reason for the fuel economy. If you don't believe me, look at the 2002 Civic EX which it too has vtec-e, just like the Civic HX from 1996-2000 and it's rated at 30mpg.

 

Yes it helps but they are 2 different motors.. 2002 Civic Ex motors are completely different from 96-00 civics

 

Keep that y7 in there untill it blows up then swap the y5 in. Thats why you bought my ecu right?

 

There are a few members on here with hx's that get some great mileage out of them. The best I've done was 450 miles in a tank.

 

You're the one that's wrong. The 01-05 civics are D-series motors and the EX motor (D17A2) in the 01-05 shares the same type of vtec (vtec-e) as the D15Z1 and d16y5. Any member that is getting great mileage out of their HX, it's PRIMARILY due to the transmission. The engine with the vtec-e and the lean-burn certainly helps but it's not THAT big.. To give you a hint, check out the Civic VX from 1992-1995 and compare the california one with the federal one.. Federal gets 3mpg more because it has lean-burn while the california ones don't have lean-burn.