Replace Entire Engine as Preventative Maintenance?
 

Yes, you read it right: Should I replace my entire engine as preventative maintenance?

Before you start typing, read on...

I race my Boxster extensively and drive it to/from the race tracks. The race tracks vary from 1 hour to 6+ hours (each way) from my house.

Racing experience suggests that 2.5L engines last about 60-80 hours on the track (which is a lot of time at 5000-7000 rpm). This rough estimate of engine life is highly variable with some engines failing earlier and some lasting much longer. Its impossible to know how long any individual engine will last. So there is no way to know if I have 2 hours left or 25 hours left.

My current engine has 75 hours of racing time and I already have a replacement engine sitting in my workshop.

The effort and minor costs to DIY the replacement swap is within my time available, tools (including a four-post lift at my house), and skill set.

The downside of experiencing an engine failure at the track is the time, effort, and general PITA to transport me and the car home. I could ride with the tow truck driver but for a long drive (more than 2 hrs), I'd probably rent a car locally and drive myself home. I have AAA 200 mile towing but the furthest tracks would exceed that limit and potentially I could be looking at a $600 bill to have the car towed home. While that might sound like a lot, that level of expense is already built into my racing budget so it wouldn't create any financial strain. But with that being said, I certainly could find a better use for $600 than paying a tow truck.

In general, I tend to follow the "if it ain't broke don't fix it" theory but not exclusively.

So, do I replace the engine now to preemptively avoid an engine failure or just drive/race it until it fails?

Now start typing... :)

Can you just do races closer to home, or within your AAA towing range until it lets go?

Can you assess the likelihood of collateral damage to your car if the engine lets go on the track-eg oil or coolant spill in front of a rear tire that could cause a spin?

What is your confidence level in the spare engine you have ready to go?

Tom,

Is there a typical failure mode that can be inspected for wear/potential failure?? Maybe with a boroscope? Oil test, etc...

If you have the means i would change it and inspect the engine for wear and see if it's renewable. Better that than being stranded.

Just imagine...
 

...how much fun the bar stories will be....."remember that time my engine blew on the back straight and the Mustang behind me spun out on my oil and he flipped into the armco?"

Let her blow up. Fun times. Builds character.

:cheers:

I say yes if you already have a good back up motor. I know of a guy who was racing his spec at cota and blew his motor. Cota gave him a bill in the thousands for cleaning the oil off the track. Last I heard he wasn't going to pay it. Even besides the chance of dumping oil on the track, there's the loss of time and money spent for a racing weekend.

For you, I don't see this as a monetary equation. The cost of your replacement engine is insignificant in the balance of what you have spent on preparing the car for the next race day. It is a maintenance item and has completed it's expected service life. My guess is that the more significant cost is the loss of a race day due to a failure that could have been prevented.

So, what do you do with the old engine? I assume that it is still more cost-effective to buy used rather than rebuild. There is a finite number of 2.5s available though. Hopefully there's a shop out there to gather them up as cores and rebuild them for the street.

Hi,

from a race team perspective i think you're right. Race engines are periodicaly revised. But that means the race engine is rebuilt completely. And this is done because it's cheaper to rebuilt a running engine than to rebuilt a broken engine - engines can fail at every time - even newly rebuilt ones. But that also means that the engine you put in needs to be completely revised / rebuilt on a professional level.

Engine swaps can always make problems, because peripherical parts like hoses, clamps, plugs and so on can fail. Because your car is 10 years plus old and materials deorientate over time and heat cycles i would also take this into consideration. Also you have to setup the car completely after a revision. So i'm shure there a lot of things that can make a swap more time consuming / expensive than one think at first sight.

Because the car is old and the engine is also old i would go the preventative line - if i would have the time and budget.

Regards, Markus

I lost count, what was Jake up to 36 modes of catastrophic failure? Your replacement engine has about the same probability of failure at any time. Maybe more since it's untested. If current engine shows no significant loss of power then I'd do compression and leakdown and go from there since emperical evidence indicates most fail from some issue long before they wear out. The ones that don't fail run for 300k (Jager anyone?? and how many out there we don't hear about) and definitely skew the data.

time for a trailer. your track car no longer has to be street legal (you have your targa for that, yes?) the inconvenience of blown engine is reduced. depending on size of trailer and tow vehicle, you could even bring your spare engine with you - lots of guys there willing to help with an engine swap in-situ.

What he said.

You can tow your car to the track, and if there is a problem, you just load it up and head home (winch required). The other benefit of this is that you can bring all the stuff you need like chairs, awnings, tools, jacks etc... If you have a trailer, then would't necessarily need to do the preventive engine swap IMO,just have a spare ready to go to minimize the downtime. I have just been through all of this, and it is not fun:( but having a trailer is awesome:D

Assuming you have an off season -- I'd replace it. But, you are replacing with a unknown time bomb if its a junkyard used engine.

Then take the now in-car "used" engine -- and do a rebuild of it so that you have a back-up just in case. I haven't checked in awhile -- but it's probably $2k in parts to rebuild (depending on how crazy you get)

What have you experienced in the past as failures? Bearings? Rod bolts? lifters?
There are only a couple special tools you need to rebuild the engine specific to the Boxster. The only tricky part is getting the blind piston circlips in. you can make a homemade tool for that -- or buy Porsches.

Mike

Realistically tho --

Cost of trailer + cost of truck ownership comes into play.

I've always admired Tom's ability to drive to/from the track.

I do have a drive to the track Boxster S -- and I love the convenience.

That being said I have a Cayenne TT and a 24' aluminum enclosed for my
actual race cars -- including a new to me Spec Boxster.

Mike

I believe Tom has said in other posts he always just installs used engines because he finds it way more cost effective than a rebuild, even to the point of leaving the factory IMSB in situ. The cleanup bill from the track is another consideration for a preemptive engine change.

A quote attributed to Greg Brown from Precision Motor Werks, Anaheim, CA "What part of Porsche Racing did you think is going to be cheap, is it the the Porsche part, or is it the Racing part?"

stone's is a race car, not a track car. if it walks like a duck, etc.

Thanks for all of the great thoughts! Here are a few responses to some of the questions...


Yes, that is a possibility but I would prefer to maintain the racing schedule based on my racing goals than having to work around a potential engine failure.


Its almost impossible to know what might happen when it finally fails so I'd have to say 50/50.


As someone else mentioned, there are 30+ failure modes and only a couple could be inspected.


Well stated and right to the point! :cheers:


Yes, you accurately described the situation. I like your statement about "expected service life", that makes a lot of sense and is a good case for replacement.


The old engine could be rebuilt or sold as a core for someone else to rebuild. It is more cost effective to buy used than have professional rebuild but DIY engine rebuild is probably cost competitive.


My list has 31 failure modes and Jake probably knows of several more that I've never heard of. And you are correct, the replacement engine is a complete unknown but it was running well when it was removed from the donor car so it will run, the question is how long.


Yes, I use the 911SC Targa as my daily driver; the Boxster is only used for racing (including commuting to/from races). Your suggestion of a truck and trailer is an good solution.

But I have to admit, I really like the romanticism of being able to race a car that is driven to/from the track but maybe that time has come and gone. Something to seriously think about.


Yes, there is a racing break from mid-December to early February which would provide time to do the swap. I don't think of a used engine as a time bomb since it was running perfectly when it was removed from the original car. The question is will it last 40, 60, 80, or 100 hours.


Doing a DIY rebuild is a good idea and would be a fun project. The cost would be competitive with another used engine.


My personal experience for 3 engine failures is a failed lifter, failed lifter carrier, and a failed crank bearing. None of those failures released any fluids onto the track.

Since the current engine has 75hrs it "should" fail during the next race. For that reason I would change the engine prior to racing again. If it blows it will probably be useless for rebuilding, Where the current engine should be ideal to rebuild.

Try to find out how often the top racers have to "refresh" their engines to prevent failure. I assume you are having your used oil tested.

My god. most of us pace all night debating if we should replace our perfectly good water pumps

Not sure if you have a tow vehicle available but if you do, how about renting a u haul car trailer and start to trailer to the longer events. Less hours on your engine translates to more hours racing and if you blow, you are towing yourself home

and tires. trailer would pay for itself in tire wear. not to mention ensuring you have the proper rubber at hand should conditions change.

Sounds like you have no history on the other engine outside of that it ran when removed, so does yours if you choose to remove it now. How do you know that you are putting in something more reliable. If this was a fresh motor or one you know well it would be one thing. All you know is that your engine is nearing it's useful life, you have no idea if the other is better or how much. Sounds like you will be towing it one day or another, with this engine or the "new" unknown unit, so just prepare for the tow and let this one run till it blows.