CRX Efficiency

[dresp]

I had to abandon the 87 Rex shell I was after (no title, liens, standard excuses a la, "Just have the guy come out and he looks at the VIN and they give you a title..." Yeah, sure then why didn't YOU do it? ... "Uhhh? I don't have time?") And the thought of finding an 84-87 HF motor was daunting...

But fortunately, as one door closes, another opens, and I have my sights on an '89 DX in good condition (Tucson weather! 350 sunny days a year!)

Like the '87, I want to make a HIGH MILEAGE CRX. This means the HF engine, the HF tranny and perhaps some mods (if they can be done) to the computer or what have you to maximize efficiency and minimize power... which probably sounds like heresy from what I read in the other messages. For the life of me, I can't figure out why more people aren't going this route! $40,000 for a Prius that gets 50 mpg? NUTZ!

I imagine that many of the readers here have experience ripping out HF engines to stick in the D20's or B16s or what have you... Has anyone done the reverse? Or can anyone recall working on an HF? Will I need new motor mounts? A new radiator? New... stuff? What needs to be replaced and what can stay in a DX to HF transition? Will I need to get HF wheels? (They're smaller). Any help for this would-be Grandma Driver?

 

[Periculum]

I owned a 91 HF CRX for a couple years, then something in the tranny snapped. It was getting 30-33 city and 46 HWY. While these aren't the marks the car got when it was new, I understand from several people that that was near the best you could get out of that car fifteen years after it was built. After the tranny snapped, I grabbed up a ZC from (shameless plug) hmotorsonline. While the swap (all things considered) wasn't cheap, I get BETTER city gas mileage than I got before with the HF. My highway sits at 42 or so from the past few trips I have taken. The reasoning is that the ZC motor runs roughly 250% of the power that the HF has, the ZC is at no loss to get the car moving (which is where most gas is spent). If anything, pairing the ZC engine with the HF tranny might give you good highway results to go with the 30ish city that nearly every (stock) motor in that car can get. '


If you still want to change over, the motor mounts will be the same. Radiator will be the same as well (they will sell you a bigger than original one at Advanced auto anyway, still fits)

You shouldn't need to get new wheels unless you want your speedometer to be dead on (unlikely by this age anyway).

I forget exactly how the wheel hubs work, but I know that the HF are different from the SI, the number of splines is different and therefore uses different axles.

Don't take just my word on all this, more will post, listen to them as well. I'm just sharing my experience. I bought my CRX HF for the purpose of gas mileage as well (pizza delivery) and the ZC motor/transmission has shown to be just as good city as the 62hp HF motor and more fun

 

[LS_VTEC]

I had an HF. As long as the engine is healthy you shouldn't have a problem getting great gas mileage. When you get it, take it to your local shop and have them do a run-rite and a cooling system flush. This will get you going fresh. Also change the distributor cap and rotor, put in new spark plugs/wires and a new fuel filter. All said and done, you should get good gas mileage.

 

[Jeef]

With your dx you are starting with more weight than the hf off the bat. How much i can't remember. With that being said if you put an hf driveline in this car you have a weight disadvantage from the start. This means the low hp hf motor has to work a little harder in this car than it would in an hf. For wheels get some lightweight wheels and tires, probably what the hf came with stock would work well. Look up the list on what the dx has that the hf doesn't. See where you can shave some weight.
If it were me I would be running a zc or a6 motor in there with a tranny that matches what kind of driving you do.

 

[dresp]

Periculum - Thanks for your response and experience. Comparing a blown out old D15B6 of unknown pedigree to a new ZC is a little like apples and oranges. I would be putting a rebuilt D15B6 in... I will look into this ZC business though. If I could get one of those motors with variable cam profiles, I might consider it. Thanks for giving me some more options and ideas.

LS_VTEC - Thanks for good advice on what maintenance will help if I manage to find an HF (most of them have been scooped up by tuners because they weigh less, but I am looking... I want the classic "grandma car") I am willing to pull the engine out and rebuild it to insure that I get peak performance and efficiency, but I don't want to do it until the compression falls off.

Jeef - Thanks for the specific advice! Is the ZC or A6 motor for efficiency?

I talked myself out of converting a DX to HF. I will be looking only for HFs now. Hopefully I will find a good shell for cheap and stick a rebuilt HF motor in there.