Time between engine rebuilds for HP

[BruceG]

Anyone have any experience with the above....ie spitfire,sprite,midget? Pretty expensive rods,pistons etc going in each time. Assume appr 3 races per season. Thanks for any info!!

[shlowone]

Bruce, Are you buying another car? I have a real nice RX7 if you're interested :eclipsee_steering:

I didn't see you on the car counts for 4/10-4/11, the STO car not ready net?

[quadzjr]

unless something fails I don't see why you would need new rod and pistons. Unless you want to just throw money at it, or have dyno evidence showing that you are loosing a substanical amount of hp. I would leave it alone.

If there is something wrong with it, do the typical compression, leak down tests and work from there.

However if you feel un-comfortable about the motor, then pull it apart and measure every single thing prior to removing it and compare it to whatever to set/speced it to when you built it.

Also depending on when it was built the aftermarket and capabilities have increased ever so slightly so you could make jstu a little bit more power with a new rebuilt engine utilizing the new technology. Whether or not that is allowed in the class for said engine is another thing entirely.

[BruceG]

Bruce, Are you buying another car? I have a real nice RX7 if you're interested :eclipsee_steering:

I didn't see you on the car counts for 4/10-4/11, the STO car not ready net?

Just looking at classes where I don't have to race with the fast ones like you, my friend!! Seriously, I was curious as to engine life in some of the older tech cars of the HP ilk.

[quadzjr]

Just looking at classes where I don't have to race with the fast ones like you, my friend!! Seriously, I was curious as to engine life in some of the older tech cars of the HP ilk.

as a more specific answer to teh older cars, they are just like anything else. A top flight prod motor life span is very small. However they are not built for reliability. I know a good bit of the run-off guys put new motor for both prodfest and Run-offs.

However a mildly built one should last you all season without issue.

[rsportvolvo]

I would start by logging run time and oil pressure. Then perform regular compression and leak down tests? If they all check out ok then keep running the engine. Also, depending on the power being made that could be an additional factor to keep track of. So adding periodical dyno runs would help correlate the compression test, leak down test and oil pressure figures to rebuild intervals. Just thinking out loud here.

[BruceG]

I would start by logging run time and oil pressure. Then perform regular compression and leak down tests? If they all check out ok then keep running the engine. Also, depending on the power being made that could be an additional factor to keep track of. So adding periodical dyno runs would help correlate the compression test, leak down test and oil pressure figures to rebuild intervals. Just thinking out loud here.

Thanks for your help folks.....I guess the question is with similar time racing to a spec pinata is engine life in these prod cars a lot shorter or similar?

[lateapex911]

A British Prod car compared to a Spec Miata!?!?!?!?!?

Think about it like this: A mosquito vs a tortoise.

[BruceG]

A British Prod car compared to a Spec Miata!?!?!?!?!?

Think about it like this: A mosquito vs a tortoise.

No question there, Jake. I agree completely, no comparison speedwise. I was curious because you see some HP car engine rebuids using Carillo rods and Mahle pistons which gets pretty pricey.

[quadzjr]

Thanks for your help folks.....I guess the question is with similar time racing to a spec pinata is engine life in these prod cars a lot shorter or similar?

It is considerably shorter.

[JLawton]

No question there, Jake. I agree completely, no comparison speedwise. I was curious because you see some HP car engine rebuids using Carillo rods and Mahle pistons which gets pretty pricey.

I'm not so sure Jake meant speed in his analogy. I think he was trying to say they are at opposite ends of the spectrum. One needs a CRAP load to maintain, the other needs very little.

[BruceG]

I'm not so sure Jake meant speed in his analogy. I think he was trying to say they are at opposite ends of the spectrum. One needs a CRAP load to maintain, the other needs very little.

Thaks Jeff. You both confirmed my fears on HP!

[shlowone]

Not fast, Shlow....

[RacerBill]

Many years ago (probably still true today) was that the National Prod racers built 45 minute engines and the Regional Prod racers built 30 minute ones!

[BruceG]

Not fast, Shlow....Shlow today, fast tommorow, AJ....LOL:dead_horse:

[DogDoc]

I had a GT5 Mini, 1275 A series, probably about 135 HP. The PO changed rod and main bearings every three races. Good rods and pistons should be good for a good while, rings are another story. 6 -10 races if you don't run air filters, good bit longer if you use decent air filters. BMC A series are 3 main bearing cranks so you have to stay on top of bearing wear.

[lateapex911]

Bruce, the short answer is, the typical old school HP engine will require boatloads more care and feeding (new bearings, new parts, valveguides, etc etc etc, ) over any given period than a current tech SM engine, or IT type engine of relatively modern standards (Honda/Acura, etc).

One reason SM is sp popular is because you don't need to be a full time mechanic that can deal with the constant upkeep and tuning issues the old cars demand.

For your SM money, you can be within a hp or 3 of the top builds for a much longer period....that same yardstick in HP will cost you time and money many fold over. That said, the level of competition in the HP type classes is generally thinner, and it's probably easier to score a 3rd in an HP car at a regional race...but...it might also be called "last". ;)

[BruceG]

Bruce, the short answer is, the typical old school HP engine will require boatloads more care and feeding (new bearings, new parts, valveguides, etc etc etc, ) over any given period than a current tech SM engine, or IT type engine of relatively modern standards (Honda/Acura, etc).

One reason SM is sp popular is because you don't need to be a full time mechanic that can deal with the constant upkeep and tuning issues the old cars demand.

For your SM money, you can be within a hp or 3 of the top builds for a much longer period....that same yardstick in HP will cost you time and money many fold over. That said, the level of competition in the HP type classes is generally thinner, and it's probably easier to score a 3rd in an HP car at a regional race...but...it might also be called "last". ;)

Jake..talk about help and a fountain of knowledge on so many subjects!! Thanks to you and all you guys out there for your help. I was looking at an HP spitfire but no longer .....LOL.:happy204:

[lateapex911]

There re better things to spend your money on that will be front runners and help you spend time driving, not wrenching...one is in my garage, LOL.

[Flyinglizard]

I do a compression test every monday morning post race. My new build shows 210# on my gauge. When the test shows 195 or less, I re lap the valves. Total seal rings seem to go all season. Synthetic oil keeps the whirly gigs whirling.
British race car?? They are a hobby and love, not a race car...
Run the airfilters on any high compression race engine. SCCA is just a flush of cash, flushes faster without airfilters.
I just had to do a complete TR 6 Race engine, due to injesting a small stone, smack the head, ruining a rod bearing, ruined the crank, etc.
If you are racing for money, and the airfilter will make you another 2000$ or more, than by all means leave it off. If you run with, and without the filters, without rejetting, then maybe you are off on jetting enough to negate any gains. IMHO. MM