Replace Entire Engine as Preventative Maintenance?

[thstone]

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

Originally Posted by PaulE

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

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.

Originally Posted by PaulE

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?

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

Originally Posted by jcslocum

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

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

Originally Posted by 10/10ths

Let her blow up. Fun times. Builds character.

Well stated and right to the point!

Originally Posted by 78F350

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.

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.

Originally Posted by 78F350

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.

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.

Originally Posted by 911monty

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.

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.

Originally Posted by The Radium King

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.

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.

Originally Posted by seningen

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.

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.

Originally Posted by seningen

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)

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

Originally Posted by seningen

What have you experienced in the past as failures? Bearings? Rod bolts? lifters?

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.

[BYprodriver]

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.

[kk2002s]

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

[bwdz]

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.

[thstone]

Originally Posted by kk2002s

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

Lol! Yes, racing will have you thinking about all kinds of things that a average owner would never consider to be a concern.

Originally Posted by kk2002s

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

I am seriously thinking about the towing option but mostly to minimize the impact of getting myself and the car home.

[thstone]

Originally Posted by BYprodriver

Try to find out how often the top racers have to "refresh" their engines to prevent failure.

The majority drives them until they blow.

Originally Posted by BYprodriver

I assume you are having your used oil tested.

No, I do not, but maybe I should reconsider doing so. Very good suggestion.

[BYprodriver]

Originally Posted by thstone

The majority drives them until they blow.



No, I do not, but maybe I should reconsider doing so. Very good suggestion.

Yes after every race remove the oil filter & get a sample of the oil which should be what Jake Raby recommends for racing, Joe Gibbs "XP50" ?? This can establish better wear predictions & find the "weakest link"