VX engine build ideas?

[gijoe985]

Hey all,

So, if I were going to rebuild my VX civic engine, what internal mods would help mileage? I've built performance motors before, but the switch to fuel performance sometimes boggles my mind. Other than a quality rebuild, what internal mods would help? I'm figuring that anything that would help burn fuel more efficiently.

I dont want to port the heads because the velocity is probably better at the current size, but a polish may help. As well as polishing and removing hot spots in the combustion chamber.

How about slightly increasing compression? Lightened flywheel? Knife edged crank?

Your thoughts are appreciated.

[drmiller100]

lighten the flywheel.
do you have the vx trans? it is longer geared.

other then that, i'd put it together fresh and drive it.

[gijoe985]

How about the crank? Seems like a lot of work. I figure it would help, but might not be worth the effort.

[Ecky]

Raising the compression or increasing the stroke should both provide benefits, but remember that milling the head or using a thinner gasket will both throw off mechanical timing.

I wonder if you'd have issues with detonation during lean burn if you raised the compression a little? It only happens under low load operation, right?

[gijoe985]

Originally Posted by Ecky

I wonder if you'd have issues with detonation during lean burn if you raised the compression a little? It only happens under low load operation, right?

That's one reason I figured I'd hit the combustion chamber to reduce hot spots.

[Ryland]

I would balance everything so it runs as smooth as possible.
The VX fly wheel is already lighter weight then other models.
Indexed NGK V-power spark plugs once it's all together.

[EF TuneRR]

Originally Posted by Ryland

I would balance everything so it runs as smooth as possible.
The VX fly wheel is already lighter weight then other models.
Indexed NGK V-power spark plugs once it's all together.

I'm pretty sure the above comment about the flywheel was meant towards an after market light weight flywheel. I'd look into a 7.5-lb Fidanza flywheel.

Anything the removes rotating mass. Lightweight connecting rods and pistons. Have the entire rotating assembly blueprinted and balanced. Also, maybe look into knife-edging your crank.

Honestly, learning to drive the car and learning/changing your driving style will probably be more cost effective than spending the money "building" the engine. Plus, your car won't have any down-time so you can enjoy it. I'm not saying DON'T build it, but maybe hold off on doing it for a while.

[02ws6]

Ive recently rebuilt my D15Z1 and can say that there isn't much to do on improvements of the engine for FE..

I put fresh bearings and rings with a simple hone on the bottom end. The rod bolts got replaced with ARP hardware and the cylinder head got milled .0010 for a little compression. Gas mileage cars like compression. I also polished the exhaust ports just becuase i figured it couldn't hurt. I bet most of the cars on this site could use a valve adjustment. I wish I had a picture of the carbon that was caked on my valves. And the guy I got it from said he averaged 50mpg in his VX. Kinda excited to see how the car will perform now that its all freshened up.

As far as ideas for down the road.. I really like the idea of turbo charging.. If there is turbo diesel jettas out there getting 50mpg then I know I can improve the Z1 with a very small and simple turbo setup.. A small t2 turbo that'll spool really quick and just run 3-5psi max. Don't know the complete logistics of this setup since from what I understand you can't chip the p07 5wire ECU but with the car already having wideband I wouldn't think it to be too much of an issue. 2" piping and a small factory intercooler from an eclipse or something. My ideas run wild with this stuff but I just need to get my car on the road first and work the initial bugs out of it..

[gijoe985]

I would be curious to see how other people felt about turbocharging a vx?

[some_other_dave]

I wouldn't think that turbocharging it would be needed. Unless you're swapping it into something large and heavy, in which case you can use the turbo'd VX engine to replace a much larger and less efficient motor...

One thing to think about: When you drive for economy, you are running at relatively low RPM. Low revs means that knife-edged cranks, boat-tailed mains, etc., will have much smaller effect than in a race car.

-soD