Originally Posted by Relic1
IMO the VX engine is great for fuel mileage but not much else.
I get 44mpg with a DX motor and a CX gearbox (same as VX). What does a VX get?
I think the mpg of these low-torque lightweight engines has more to do with the gear ratios than the power output/number of valves. You're installing an experimental 8-valve 1.5L engine in place of a no-fuss 16v. The head casting on both are identical. The valve bores and sizes are nearly identical. The 16v head flows better. Those are just facts. I just don't want you to be disappointed if the car is a lot slower when you're done with it. A DX is 300lbs heavier, and that engine is 10% less powerful.
You'll need that P07 ecu to make it idle right. You have to keep the egr functional like Relic1 said.
You can't change the intake manifold, throttle body, or AICV parts between them and ever expect it to idle right. All of those parts have significantly smaller bores on the VX, and thought it would be nice to keep the big stuff, it's all matched to the ECU.
Your exhaust is totally different.
VX's have an oil cooler, so the coolant lines are different than your DX.
VX's don't have power steering, so you'll need to change your crank pulley and PS stuff over to the other motor if it's equipped on your DX.
I just think you should reconsider the swap if you haven't started because you can buy an engine gasket set for $90, a new set of rings (provided the block doesn't need any machining) for $60, and a new set of ARP head bolts (cost about as much as stock) for $60. If the head needs work (you'll know after you get it off and inspect it if it does), Napa will rebuild it with a basic valve job for about $100. Add $100 for new timing belt parts and a water pump. Re-use everything else and bolt it back together. Good for another 60-90k trouble-free miles, keep your power, and no car-hacking BS or other $ to spend on exhaust/ECU/wiring to make it fit.
If you've already started this project, I wish you the best of luck and hope that you already know this. So aside from that heads-up, other people here have done that swap, and can give you more info than I can. You're in the right place for help.