erioshi

My first post here on RL so please go easy on me. I'm a former 928 owner who's feeling a bit nostalgic about the car I used to have. It was an early euro automatic, and was painted in, I believe, Petrol Blue with a blue interior. I really liked the car, but was dissatisfied with it being an automatic and also disliked blue interior. Yet I do miss driving that car, it was wonderful for weekend road trips.

I'm currently looking at picking up an OB that is essentially a basket case in need of rescue. Yes, I understand the economics, and the potential pain I would be getting into. But I really liked my last euro, and the car I'm considering is straight, solid, complete, and rust-free. It is also a euro 5 speed without the side protection strips. I would prefer a non-sunroof car, but finding one with even these other traits has been somewhat difficult.

Planned use would be for summer fun and weekend escapes with an occasional cross-country jaunt. I'm not looking to build a race car or track car, I get my racing fix with a different vehicle. That said, the car would need to be reliable when subjected to occasional track-day or hill-climb use with friends. Track use would probably be limited to between two and four weekends a year.

As I'm considering a potential plan for reviving the car, I find myself running into a performance vs cost question that is centered on the engine. Unfortunately I'm not familiar enough with the 928 to know what the real world costs of upgrading and bringing the original engine up to speed would be.

So here is my question. When looking only at the engine and considering only the cost of parts, necessary machine work, potential upgrade parts and any required supporting components (fuel system upgrades would be an example), when starting with an M28/01 engine that is probably sound, but quite possibly needing at least one head gasket, how far would an engine repair and upgrade (or Porsche engine swap) budget of about $5,000 go?

The real goal would be to improve performance, and hopefully by a significant margin. My yardstick for any suggested upgrades would be a GM 5.3 LSx swap. While I would prefer to keep the car Porsche powered (or even a later Porsche engine swap), for that same $5,000 I could do the GM swap and add upgrades that would bring the GM engine to between 350 and 400 crank HP while meeting my reliability needs.

While I'm not stuck on any specific numbers, the road cars I've owned and enjoyed driving the most are usually a bit to the fun side of a 10:1 power to weight ratio in wheel horsepower. I feel that is typically enough power to be fun, but not so much that driving a car becomes become work or requires hard-edged suspension and/or chassis compromises that diminish a car's character.

I'll be doing essentially all of the mechanical work that doesn't require a machine shop, so labor costs should not be considered a constraint. I have also successfully completed other projects that have required this level of work, so I'm going to presume I'm not completely over my head .. yet.

Also please remember the budget is just for the engine and related cooling, oiling, fueling and engine management needs. Please also consider that a well-rounded upgrade plan is essential; adding a pair of turbochargers and not considering the costs of the required upgrades to the other systems or building an engine that is temperamental and/or failure prone would be failures. Finally, upgrades to other parts of the car are outside the scope of this discussion and will be address separately. Please also remember that the purpose of the car is personal enjoyment along with occasional hard use, and those priorities of use will take precedence over originality and correctness. This car would be built to be driven.

Thoughts?

snoz

Unless you are really committed to (or need to be committed because of) the 928, you might look at other vehicles. There are others that give greater performance per dollar. Having said that, none of them are near as cool as the 928 imho.

erioshi

"... or need to be committed because of ..." is probably the most accurate.

This is something I'm considering for the fun of the project, not as an attempt to build an all-conquering uber-auto.

The Forgotten On

You could easily add euro S heads and cams to give you a good sized HP boost along with the intake from a euro S. Combine that with a well designed exhaust and you should have around 300 HP.

Be sure to use the oil pan from a 4.5 along with it's pickup (80-81 is the best designed) and a crank from a later engine as it has better oiling holes so you are less likely to destroy the bearings from lack of oil when cornering.

You should be able to do this for under $3000 in parts and have a very reliable engine that can take some track day abuse. This includes a general rebuild of the engine with new bearings etc.

Replace general consumables like all soft lines such as the fuel lines and PS lines. Make sure your cooling circuit is in good shape and replace anything that is failing or about to.

Then add an oil cooler if your engine temps get rally hot or your oil pressure drops to an unsafe level.

This list doesn't have everything and I am sure more experienced 928 owners will add some more items. This is just for basic de days and not serious racing.

dr bob

Brian and Sean listed a 86.5 5sp car here not long ago that sounds like a lighter project than what you describe. Best of the OB styling with later S4 suspension and brakes. Ken in Portland has a chipset that works with a new fuel pressure regulator to give more than S4 power. I'd go down that road long before a massive resto project.

I'll see if I can locate a link to their thread.

Randy V

Over the years we have seen many like you.

I'd say that perhaps 3 in a hundred actually stayed with it and incurred the voluminous expense needed to end up with a worthy end result. Even then, the final car was never worth the time and expense committed.

The other 97 end up spending $10K or more to end up with a 928 worth $5K or less.

Alan

Sadly - Randy is right on the money here...

Dr Bob is pointing you in the direction best likely to yield you a reliable performance 'OB' look.

You'll need to spend more as price of entry there - but you have some performance options. 300-350HP is within reach.

Much more requires a more expensive approach but really $5K isn't even going to get you one reliable turbocharger on a 928 let alone 2.

Alan

Bmw635

Haha , so true, right now I am between the 4 or 98 cross road. Fortunately, the expense can be written off in business but the time it takes is more than the car is worth. I wouldn't mind taking my time if I had the storage but since we have a 3 car garage with 5 cars and a trailer, storage is at premium. We'll see if my wife put up with this storage issue since this was the problem I had to sell my Euro 635 owned for 21 yrs.

erioshi

Tough crowd. Believe me, I know what can happen to a 5k turbo-charged project of almost kind .. usually it ends up as just a pile of scrap. I'm frequently the guy that gets called when a friend of a friend has gotten themselves into a project that has either failed or is failing, and they need help sorting it out. And I'm also the guy usually trying to talk my friends out of projects like this .. unless they really do understand what they are getting themselves into and have the resources necessary to see it through.

My last turbo-project was a new, straight off the showroom floor Evo, and after adding up all of the costs, I had probably an additional 50% of the car's purchase price in upgrades. It was, however, an absolute demon on the track, and very reliable. I've sold that car, and now I'm essentially just looking to build a weekend GT.

I'm pretty sure I didn't say I wanted to build a turbo car with a 5k budget, and that I said such a project would be destined to end in failure. I guess I didn't say it specifically in my original post, but boost of any kind was never a consideration for this project. That leaves mechanical tuning improvements like heads, cams, rods, pistons, etc. or an engine swap.

I did say that I knew this was not a winning financial proposition.

Given I'd be starting with a 35 year old car with essentially an unknown history, almost everything will need to be touched, inspected and repaired or replaced as needed anyway. My thinking is that it is alright if the car takes two or three years to complete from start to finish. Obviously the engine would only be a small part of that. Suspension, brakes, steering, electrics, paint, interior, etc. will all need to be looked at. Taking on this car as a rescue project would more of a hobby activity for me.

So would the car Dr Bob suggested meet all of my criteria? Can it reliably do four track weekends a year along with seeing regular summer driving duties without engine related upgrades and deliver a power to weight ration of better than 10:1? If not what kind of additional investment would it take to bring that car up to what I'm seeking? I'm thinking I'll need between 350 and 400 crank HP to deliver a WHP rating of better than 10:1 with a driver...

Alan

You can't get to 400 HP without boost or significantly more displacement - $$$ either way.

What Dr Bob proposed can get you to 300-350HP but probably not more - will stretch your budget at 350 too. Lots of small incremental changes on a Porsche are expensive too.

Alan

erioshi

I'd love a car like this. Although I would find myself looking for more power.

Richards 928

It will be tough to build the performance you describe for $5k. Seems more likely in the $5-$10k for the performance build to 350-400hp (assuming you want a reliable driver when you are done).


I recommend more research on the LS swap. I have never heard of an LS swap (or build for that matter) for under $5k and I am talking Chev-to-Chev. Chev-to-Porsche? I expect $15-20k would do it and it will take a year of weekends to iron out the bugs.

Jetdriver69

Even a straight stock rebuild of a 4.5 with you doing all the work is expensive, I know.

Just the piston rings, if you can find them, are super expensive. The 5.0 rings are less for a whole set than for one piston on the 4.5.

Then you have head rebuild, any machine work, all gaskets, bearings, water pump, hoses, lines, injector refurb, etc, etc. etc.

If I had it to do over again, I think I would have done the 5.0 hybrid for about the same cost of a 4.5 rebuild and gain more power.

Don't forget about the manual gearbox/clutch, they are notorious for having crunchy 1st and 2nd gears. That ain't cheap to fix. and yes I know that too.

Oh yeah, the suspension, steering rack leaks, shocks, tire/wheel upgrade, tie rods etc.

And then there is the interior upgrade/refurb, stereo, interior electrics/switches, fuse panel clean up, AC system, etc, etc.

You WILL spend more than the OB car is worth for a semi restoration, so be prepared for that. Once you are committed, thats it, you're in all the way. There is no such thing as getting halfway screwed.

So you better really like the car you got and look at every system with an eye of a buyer, not an owner. Most likely you will touch every single system of the car, I know I did to get everything to work or to improve what you have already working.

I agree with the Chevy hybrid, none of those I have looked at have the bugs worked out and it is more like a kit car than a Porsche. But that is not to say there are fine examples out there and their owners are proud of their work. It is just not my thing.

As most have said, you are better off finding an example that someone else has put all the money, time and cussing into and pay up front.

You will be financially happy with that decision, but money savings is not why we bought a 928, is it?

x98boardwell

What Alan said both times.

erioshi

Thanks for the more detailed responses as this is exactly the type of information I was hoping to be able to receive. It's easy to sit down with a parts list and and some ideas, but the reality is that kind of build usually usually ends up costing a good 50% more than you expect .. if you were very careful with the parts list. Large projects always fall into the theory vs. practice trap, and real world experiences are exactly what I was hoping to learn from.

It looks like if I were to pursue this car and stick to my proposed 5k engine budget, my choices are to accept a Porsche engine build looking for somewhere around 300 crank HP with a emphasis on upgrades to improve track survival, to build a nice Porsche engine based driver at about the same 300 crank HP power level and forget the track-day stuff (and save a bit of budget), or (please forgive my tongue-in-cheek) to desecrate a hallowed basket case 928 and do the GM L33 swap. It does make for a tough choice.

From a common sense perspective, if decide to keep the car with Porsche engine, it really does just makes more sense to start with a different car. The problem here is that any 928 that I start with sounds like it will need a considerable level of investment and preparation to become a semi-regular track-day survivor. This kind of works against the idea of wanting to be able to use the car to travel cross-country and do weekend track-days on tracks I'd love to race, but are outside of where I normally compete. And has been pointed out, for a track car, I 'd need to put hands on every part that moves or wiggles, so even a well preserved driver many need quite a bit of work to bring it up to spec.

If I were to do a GM swap, I could contain the costs by skipping an LS1 or LS6 and use the smaller L33 engine. It would still be a modern, aluminum block LSx gen four engine, but with a 5.3 liter displacement, and the ability to use pretty much any available bolt-on LSx performance part. Crank HP is rated at about 300, and they respond very well to upgrades. There are well documented upgrade paths for bringing this engine to about 400 crank HP for very reasonable money. The heads and block also have many of internal upgrades found in the C6 like improved intake ports and an updated connecting rod design. These also tend to cost at least $2K less than a typical LS1 drop-out. Lots of potential, but quite a bit of work to make this kind of swap feel OEM correct.

Ironically, all of my L33 knowledge has come from another swap project. A friend had picked up a very nice RX-7 FC (2nd generation RX-7) and was considering a turbo rotary engine swap when he kind of tripped into the RX-7 GM swap scene. After doing some careful research on the economics and impact on the driving dynamics, he decided that doing a GM swap would be a better choice for his use of the RX-7. That lead me to missing my old 928, searching and checking out different cars over the last several months, and here we are. While his swap isn't quite completed yet, it is going well, and the parts prices are very reasonable. Getting the car up to a proper OEM feel and making everything work correctly is work, but every issue we have encountered has been solved before (sometimes in a variety of ways) and documented. In this case the "LSx in everything" movement has really worked in our favor.

It's also probably worth noting that if I don't save this car, it is most likely destined to end up being "customized" by someone else who is looking to build an over the top, heavily modified, tuner-style custom out of it. So while a GM v8 swap might not be ideal, it's probably more in character with the 928's roots than the alternately proposed future twin-turbocharged skyline or supra straight six swap. Never mind what's been suggested for chopping up the body, changing out the headlights and re-inventing the interior. My thinking was more of a subtle pro-touring build than crazy custom FnF style tuner car.

My (rough) parts cost estimate is for the L33 engine swap is about 3.5k, so between 5k and 6k for a properly sorted and running swap feels about right. And yes, doing the whole car will cost quite a bit more. On the other hand, I have not found an alternate vehicle that I could buy or build for the same money as this project that I would rather own. Well, perhaps one, but I already have one of those parked in another stall.

Alright, time for me to put my thinking cap on, consult with my car-project friends, and see where this goes.

Thank you again very much for information.

Oh, one last question. What would an m28/01 with 38k miles be worth? One possibility is running without any major problems, but probably not running perfectly. Years of neglect, but cleaned up and revived enough to be proven sound and then able to used as a functional driver. The alternate possibility is cranking and willing to run, but probably needing to be completely gone through before it could be put into service.

Thanks in advance.