Hugh's 1987 505 STX V6 Project

By diyauto
( 1 )

Hugh's 1987 505 STX V6 Project

Compliments of PeugeotPilot @


So, having completely failed to document my California trip to pick up two V6 505s (one of which is still stuck at the border, but that's another story...) I have decided I'm not going to make that mistake when I set about reconditioning the 5-speed STX I bought from Thomas Kinder. This is my winter project, the object of which is to be driving this car next spring. Time and finances will dictate how far I get, but I'm optimistic. This car was, to be frank, absolutely worth the long drive to Roseville to get it and bring it home. It will be a very special car when I'm finished with it, and will make a nice sister ship to the STI, which I will be working on concurrently. My goal is to have both in tip-top shape next summer.

So, with that in mind, details of the project will be posted here, along with links to the videos I plan to post on YouTube in order to document everything. I uploaded the first video today, an overview of the car as it stands right now, talking a bit about some of the things that need to be fixed and some of my plans for it. Each time I tackle a major task I plan to post details and a video, hopefully to be of interest to the group and also to keep me motivated. So, without further ado here is a link to the Walkaround video, and a few pictures of my new baby. Enjoy!


Thanks to all of you for your comments. This is a really supportive group and I really appreciate that, especially as I am a member of a few other car groups (non-Peugeot) that are quite dysfunctional. Arun, I really like what you've done with your 505s and I will have quite a few questions in the future about the setup you use on your STI in particular.

I finally got the car from Lethbridge back home to Seven Persons (around 150km/100 miles) yesterday. Now the fun begins. Still cleaning out the garage so I can actually get the car inside. The chrome fender arch trim appears to be held on in multiple places by screws into the rolled edge of the fender lip - this is unfortunate, but it's also not very visible. If the screws provide the majority of the attachment strength then I am hopeful that I can remove the trim easily with a minimum of dealing with old adhesive. We'll see.

For kicks I threw the Grant steering wheel (that I plan to use in my eventual Turbo V6 505) on in place of the stock unit to see how a 350mm wheel looks. The Nardi I want to install is the same diameter and similar in design. It looks really good, actually. I will however place it a bit farther away from the driver; the Grant setup is optimized for a Series I car so the shaft is a bit long. In a day or two I hope to find time to fiddle a bit more. Organizing the garage is a huge chore, but the prospect of having some fun tearing into this project keeps me motivated. More to come shortly.


This one is normally aspirated, but in the near future I'm going to construct another 505 powered by a turbocharged and intercooled PRV V6, and detail it here in a separate build thread. That's a longer-term project. This particular STX is just getting an extensive refit and a few upgrades as I want to be driving it next summer.


I really got a chuckle out of that line as well. "Accidentally installed." I love it. If Rabin ever manages to find a company that will duplicate those springs I will buy at least two sets, one for this STX and another for the eventual V6 Turbo. Arun, you may be forced to provide measurements at some point!

Either today or tomorrow I will be pulling the STX into the hangar at work and doing a few things to it. If that works out then I hope to have video #2 posted and details here right after. I was at Princess Auto today and happened to spot some nice-looking rod ends that might be just the thing for my custom short shifter setup. Pricey, but worth it if they have the effect I want. Also, yesterday I removed the engine-driven viscous-coupled fan. I will be replacing it with an aftermarket dual variable-speed electric setup controlled by an adjustable thermostatic switch.

I also hope we can get together a few times this coming season and help each other move our projects forward, Rabin. This is half of the benefit to being part of a community like this, plus it's a lot of fun.


Right now I suspect that a stock 145 BHP STX is significantly slower than a stock N9TEA car in both acceleration and top speed. Due only to the latter's turbo lag, I think the V6 might be a bit quicker off the line, but that will be about it. Still, you have to consider that my reference point is a five-speed XN6 car, so to me the V6 feels plenty quick. I'm saving the more serious engine mods for the later V6 Turbo project, but what I do want to do with this car a bit later is rebuild the low-mileage ZN3J I have in one of my other cars to the European spec (170 BHP) and swap it in. I think 25 extra HP would be a nice enhancement. It should run with the stock late-model Turbo 505s then, at least in North American tune.

When you get a chance to dyno that car of yours, Savo, it would be really interesting to see what your power-to-weight ratio is. I doubt that any 505 I build will be able to beat your 405, but the Turbo V6 might at least come close.

Once this project is on the road I'll measure acceleration and top speed and get some actual numbers.


A quick update: I'm still trying to get my garage cleared and organized so I can get the STX inside. Soon, very soon, I can really tear into the project. In the meantime, I happened to be up at the Cayley property a few days ago and although I wasn't able to stay very long I did grab a few loose parts for the STX - specifically a set of valve covers from a disassembled ZM112 (PRV V6 from a 604) to install as well as probably the last decent sunroof wind deflector I have around. So, you may ask, why the valve covers? Well, part of my mission is to reorganize the under-hood layout of the STX so that it's more attractive and you can actually see the engine. Take a good look at the pictures of the existing setup, and then look at the ZM112 valve covers - as you can see, the crankcase breather/oil cap is on the other side. This means I can run much shorter hoses to the section of intake upstream of the throttle body, reducing some of the clutter. My plan is to have them bead-blasted, remove all unnecessary mounting flanges to make them look better, prime them with zinc chromate, and paint them black. Since I was going to check and adjust the valve clearances anyway, this doesn't really mean much extra work and I think the results will be worth it.


High time for a progress report, so here goes.  I had to kick the STX out of the garage a while ago to make room for Jamie Kitman's 404 wagon, which is pretty close to being finished now.  The winter has been so mild lately that I might just continue to work on the STX outside for the time being.  Work that's been completed so far includes removal of the chrome wheel arch covers (very easy to take off as it turns out), fitting a black deck lid spoiler in place of the blue one that came on the car, and partial stripping of the interior.  The one job I think might get a bit complicated will be the removal and replacement of the dashboard, which is not nearly as simple as in a Series I 505, but I'll just take my time and take lots of pictures so I don't wind up with leftover parts.  I want the interior of this car to be as close to perfect as possible.

On the exterior, I've collapsed the bumper shock mounts and moved the bumpers in, 1-1/2 inches at the front and 2" at the rear.  They could move in further but I was after a particular look and this achieves it.  I still have to figure out how to fill the gap between the bottom of the bumper and the air dam, which is greatly reduced but actually more obvious now.  I want the front end to have a "finished" look, so I'm leaning toward some kind of rubber weatherstripping or perhaps actually attaching the air dam to the bumper in some way.  Perhaps I can even improve the aerodynamics of the front end a bit in the process.

Under the hood, the engine had to go back together just as it came apart, so basically no progress there unless you count the removal of the viscous-drive cooling fan.  I found a dual electric fan setup on one of my Turbo cars (front mounted ahead of the A/C condenser) so that will wind up in the STX and be controlled by an adjustable thermostatic switch. We will find out this summer if that provides enough air flow, but I think it will be adequate.  If not I'll install some aftermarket units that move more air.

The fully-functional electric stereo antenna will be removed and installed in the blue STI.  The STX is going to get an aftermarket European-style antenna from a seller on eBay.  I'm also planning to fit a wind deflector to the sunroof. I've decided on a steering wheel and a few other details as well.  Even with the baked paint this car is going to look pretty cool.  It will take me a while before I can afford to have it painted, unfortunately.

These pictures were taken a while ago when there was still snow on the ground.  Colours are a bit off because of the frost on everything but they show the tucked bumpers to good effect.


This is pure gold; thanks for your thoughts, John. I gotta admit I wasn't familiar with the "bent-six" term although I guess it's obvious really. My goals for this and the other 505 build are pretty modest: 200-250 hp, mostly because I don't want to re-engineer the entire driveline. The stock BA10/5 transmission will reliably handle about 220 lb-ft maximum torque so that's the most I'm after. I've been considering just dropping the 2.5 Turbo PRV setup from an Alpine GTA into this STX and run VEMS or Megasquirt on it. Apparently this arrangement will fit the 505 engine bay. For the (later) Danielson-spec 505 project my Holy Grail is minimum weight, so I'll probably go with a normally aspirated PRV built to rev and breathe really well, like Danielson themselves did. But like any of my project ideas, these continue to evolve...

Were Volvo the only ones to offer the cross-bolted bottom end in production form? And were the odd-fire cranks cast iron then? I wasn't aware of either of these details.

I never considered the PRV bottom end to be underbuilt; it always looked pretty strong to my eye and of course I've never heard of a main bearing failure in any PRV. The cross-bolted mains just sounded like an interesting detail for a higher-output engine. Peugeot successfully extracted 680 hp from the PRV using twin turbos and intercoolers, while running it up to 8200 rpm. I'm not sure what bottom end arrangement they went with but clearly the engine is plenty strong. They used a special DOHC 4-valve head in that application.


"Make it a 3.4..." You mean 3.4L? Would that mean the Premier/Monaco crank with an offset grind and the heads and liners from the same car? As for headers, I think I'll just have them custom-made. I doubt the Peugeot exhaust manifolds are much better than the Volvo units.


A 605 is on my wish list, but I'll have to import one from France I suspect, as I've never seen one on these shores.

A little update on the STX though:  The Nardi wheel and hub are on their way, and I'll post pics as soon as they show up.  The style I ordered is pictured below:

I will not complete the interior until I get my last 505s imported from the US, as my plan is to use the very best blue dash I have in this car, and put the second-best one in the STI.  Right now I'm not sure which those are.  Both cars will get dash mats, which I've already got.  I think I'd mentioned before that I plan to rebuild and re-engineer the shift linkage to improve the feel and shorten the throws.  In addition to that I will see how feasible it is to place the whole assembly a bit further aft, as I've always felt that the reach to fifth gear was a little long from my preferred driving position.  It might wind up being a completely custom assembly.  We will see.

Progress was very slow while I was busy with the flight school's yearly Air Cadet contract, but now that's wrapped up and with the onset of cooler weather in September I will have more time and better conditions to move ahead.  I have partially fitted the body kit and the new mud guards (pictures below) as well as the new driving lights.  I am looking at some sort of lip (Rhino Lip or similar) for the bottom of the air dam, and something similar to bridge the gap between the bumper and the top of the air dam, purely for aesthetic reasons.  I'm looking for a seamless, factory look for the tucked bumpers. Note that in these pictures I've trimmed the front bumper slightly so that it sits flush, which looks much better.  The part I removed was a section of the inner molding that fits around a metal guide on each side.  The remaining structure is rigid enough that it should not warp or droop. Once all is sorted out and I'm happy with the fit I'll get the body kit cleaned up and painted body colour.  I'll probably do the same with the air dam as it could use refinishing.  The patina on the rest of the car will have to stay for the time being as I can't afford to have it repainted completely right now.

Engine-wise, the project has evolved somewhat.  Phase I will be basically status quo, with the existing engine staying put.  I'll adjust the valves, clean up the snake's nest of hoses and wires in the engine bay, paint the valve covers, and not a lot else at this point.  I want the car on the road before too much more time goes by.  Phase II will involve a turbocharged PRV, either a 200 hp 2.5 from an Alpine GTA, or possibly the 250 hp 3.0 from an A610, or a custom build using what I have available (with appropriate internal mods of course as John Lane recommends).  Either way, a turbocharged PRV is the endgame in this car, which will make it (in my opinion) the ultimate expression of the 505 STX.  By contrast, I think the Danielson-spec Series I 505 build I've talked about elsewhere will be a high-revving normally-aspirated version.


I see that it's been a while since I updated this.  The STX had been sitting outside for quite awhile, rudely booted out by the upstart 406 Coupe (which, come to think of it, I should start a build thread for as well).  About two weeks ago I drove it (yes, even with the interior torn apart) to Cayley and made room for it in the shop there.  I need to rearrange a few things before I put it on stands and really get to work.  I now have two sets of really good blue leather seats, two almost-perfect blue dashboards, and almost everything else I need to do the interior swap.

So, to reiterate, this is the plan for Phase 1:

1. Remove and replace entire interior with the best stuff I've got.

2. Completely rebuild the shifter, modifying it to improve feel, shorten throws in both planes, and reduce the reach to the shifter.  I want to move the whole thing toward the rear of the car about an inch so it's not so hard to reach from my preferred arms-out driving position.

3. Finish fitting the body kit (thanks Rabin!) and then have it professionally stripped and painted the OEM Peugeot blue to match the admittedly badly faded body colour.  Repainting the rest of the body will happen in Phase 2 along with the engine and suspension mods.  For the time being it's not going to match well, but I'm going to use some sort of cut polish on the paint and try to bring back some lustre to the existing paint.  I'll also touch up the few little chips where the paint is missing, as those may rust if not protected in spite of Alberta's dry climate.

4. Verify that all ball joints and bushings in the front and rear are good.  In Phase 2 I'll replace and/or upgrade most of the bushings, but for now I'll just change what's worn.  I'll get an alignment done as well.

5. Repack all four wheel bearings and inspect brakes and brake lines.

6. Remove valve covers, set valve clearances. Paint valve covers and reinstall.

7. Tidy up the under-hood layout by rearranging and re-routing various hoses and wires.  This will also involve wiring in dual electric fans to replace the engine-driven viscous fan.  The goal here is to be able to actually see the engine when the hood is opened.

8. Get the tachometer to work.  Really irritating to not have that functioning.

9. Add a few custom touches (different steering wheel, shift knob...that sort of thing).  Nothing too crazy.  I have an aftermarket stereo to fit to this car and I'll replace the speakers with new ones.  I also have a European-style roof-mount antenna that I'll install.

10. Replace oil in engine, transmission, and differential.  Drain, flush and refill cooling system.

11. Get the Out-of-Province Inspection done and start enjoying this great car!


Looking back on my previous posts, I see that I should explain what happened to the Nardi steering wheel idea.  I did in fact order and receive the wheel, but when I installed it on the 505 I didn't like the way it looked.  I really wanted to, but I just didn't.  Then I tried it on the 406 Coupe and it looked great, so there it stays.  The hunt for the perfect wheel for the STX continues, but I have some possibilites now including a Renault Fuego sport steering wheel that bolts right on and looks really good, or maybe something like the Grant wheel that I am saving for the Danielson project.