Jaguarx7

I have an s5 long block w/ sensors, wiring harness, ECU, etc. that I plan to put in my '88 vert, becaust the engine in the car has a coolant seal issue. I know other people have put a complete s5 engine in an s4 car before, and that a lot of people who haven't done it whine about how hard it is. This will be my winter project, and during the swap I will also be repainting the car and doing a lot of work on the interior, so wiring won't be much of a problem.
I would like to hear from anyone who's done this before, I want to know what problems or odditys you ran into and how you dealt with them. Any practical advice on the swap will be appriciated.

And don't bother trying to talk me out of this, I got all the parts for a very low price and will already have most of the interior out so I see no reason not to upgrade everything rather then just using s4 intake on the s5 block.

Jaguarx7

Also, I'll be adding a RB light steel flywheel, should I upgrade the clutch/pressure plate while I'm at it?

Icemark

You are doing a swap that will require considerable custom electrical (and possibly mechanical) modifications to make work, and will require you to assses your mechanical and electrical abilities.

First you will need to decide what ECU you will be using.

Then that will decide what approach that you will be forced to do from there.

And frankly it will be a waste of time to put a S5 non turbo motor into a S4 vert... there won't be any noticeable increase in power.

Jaguarx7

I will be using a N350 ECU, I have the body harness plug ready to splice. I'm goint to pull the dash because I have to get to the heater core anyway, that should make most of the wiring a lot easyer. I'll be using all s5 electronics, that should eliminate most compatabillity issues. As I said, it's a winter project.

Icemark

okay, using the N350, you will need to build a custom dash harness, to mate up to the N35X engine wiring harness and ECU, or swap in a 89 vert dash and body harness. (note: Not a 90-92 vert dash harness as there will be SRS wiring that would require changing the whole dash layout).

If you don't have a problem building custom plugs by re-pinning plugs and connectors, then probably the stock S4 dash harness could be used. But if you have access to a 89 dash and body harness, just replacing all the harnesses would be the easiest.

Jaguarx7

Well I'd love to just swap the entire body harness, and upgrade to the 9k tach whileI'm at it, but that really requires a donor car, which I don't have. I don't have a problem doing a lot of splicing, I'll take my time and of course I have the FSMs to refer to. I've got the engine harness for the new engine, and just found the third ECU plug with about 1' of wire, so splicing won't be too difficult, just time consuming.
By the way Ice, thanks for the reply. I'm sure that in the last few months I saw a post where someone was talking about having done this swap, and I searched for it, but didn't find a thing.

Icemark

now remember you probably won't see bid performace difference, but the Butt dyno will show you some performance, just because you did the swap.

and try some of the junk yards and parts guys for the 89 body harnesses. Rick at Indyparts or RX-7heaven might be good choices.

Jaguarx7

Well the local Pull-a-Part has a '91 vert, I got the taillights off of for $20, I'm about to get the top (in nearly perfect shape) for $95. I thought about trying to pull the harness from that car, but didn't have enough time, and it, of course, has the SRS wiring. What should I expect to pay fo a harness?
I know there won't be much extra power, but this swap will let me install my lightweight flywheel (which I got cheap with an s5 counerweight), lightweight driveshaft (which was free), and as I understand it, the full-range TPS will be much better for using an E-manage or SAFC. To me that's benefit enough.

Icemark

no, you don't want a 91 harness as it will require you to re-wire a bunch of things and have a bunch of wires you wouldn't use. Remember with the 90+ US spec verts the switches (like top control) are in different locations, the CPU (body computer) is wired radically different, the turn signals, headlights, etc are all wired different, there are stalk controls instead of gauge surropund mounted controls- it would be a nightmare to put a 90+ body harness in.

Jaguarx7

Yeah, i'd basicly have to have a complete donor car and swap most of the electronics, which isn't practical. Plus, the vert at the stripyard is an auto. Well, with the exeption of the AFM I have everything ready for the swap.