Quote:
Originally Posted by Rusty
The way I read it. It's 30 hours of run time. So every 30 hours. It needs rebuilt. That seems about right. Don't forget, you're talking about an engine living at 9,000 rpm for most of it's life.
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You are correct - full race-spec engine life is measured in engine running hours.
For instance, Carillo rods in my race car engine (5-litre aluminium block V8, makes ~530 hp @ 6800rpm) are lifed at 80 hours. Time between short rebuild (bascially rings and bearings for the short, plus service for heads) is 35 hours, so every second re-build I need to replace the rods, same for pistons.
Fasteners get replaced each major rebuild (rod bolts, main cap studs and nuts, head studs, yadda yadda).
The alternative is you break a rod and cut the block in half and junk a $40K engine.
Crank is steel and lasts 2 major rebuilds.
Rocker gear gets replaced every major rebuild, valve springs and retainers every minor - my cam runs 600 thou lift at the seat and seat pressures to avoid valve to piston interference are substantial, which means cam wear is significant ... it just goes on and on ...
A full race engine is a marvellous thing, but is an expensive beast.
That said, assembly time for a minor rebuild is still around a day and a half and a major, where everything needs to be measued and involves a dummy assembly can be more than 2 days, and assumes someone has done the cylinder head overhaul (reface valves, recut seats etc).
Never let anyone tell you a race-spec engine is cheap. I;ve done the numbers on a race-standard 4.0 litre VQ build and you'd not get change out of $45K given the need for dry-sump, at least 14.5:1 on E85 to make torque at 7000+rpm (which is where the power is), a steel crank, good rods and pistons, a pair of trick heads, lumpy cams with at least 550 thou lift at the seat (assuming you get rid of the VVEL - which has no place on a race engine IMHO) and individual throttle bodies like the Jenvey stuff from the UK.
Such an engine would make comfortably in excess of 500 hp but would require a close-ratio gearbox to make it work, and engine life between 25-30 hours.
So, when I talk about 30 hour engine life - that is the time between rebuilds ....
30 hours of engine run time should give you a season ... in my case, because I don't run the national series and our state-based race series runs shorter events (bascially 20 minute sprint races), if I am careful, I get 2 seasons between minor rebuilds, but the supposed minro rebuild this past Christmas discovered 9 thou piston to bore clearance at the bottom of the bore, so the block was junk ... a $4500 bill .... gets expensive real quick .....
In the Australia GT series for instance, there are 8 race meetings per year, with most events offering 2 x 20-minute practise sessions, a quali-session and 2 30-minute races, with 2 major events involving a 30-minute sprint and a 1-hour race, plus the 12 hour in Feb. you plan on 2 hours per meeting, plus the 12-hour which (roughly) uses your engine life between rebuilds in a season.
Most semi-professional teams will carry a spare engine in case the primary goes bang, and the amateurs may or may not carry a spare.