Modded M20 Track Reliability

[i6mt6]

How well can the M20 take modifications for track day duty?

I'm looking at a car that has been polished, ported, decked, over sized valves, IE cam, and adjustable cam gear. The engine seems to have been done right by a very experienced builder.

Should I be worried about reliability (vs a stock M20) on the track?

Thanks

[SkiFree]

If done properly, it is very reliable.....


Just depends on the mechanical bits parts involved, the tune, the builder, and the maintenance up till now.

[i6mt6]

OK good to know. It has been built professionally and has less than 1k miles since rebuild, so I believe it should be good. I'll have to check it out of course.

Good to know the M20 is stout enough to take this.

[TobyB]

Plenty stout.

But as Andrew says, and I restate because it's so critical,
the machining and assembly makes or breaks it.

Bottom end clearances and valve springs matter a lot,
and oil control is important, too- put a very good pressure gauge
on it, and then shoot that with a video camera
(or just log it, if you go down that rabbit hole)

They run for years on track, if not, often, decades.

t

[ForcedFirebird]

Get a crank scraper and windage on there for long sweeping turns, but otherwise the m20 is as the others' say. We have used 200k+ miles stock engines in long endurance race after race, and they usually give up the ghost for something related to the cooling/chassis etc.

Rocker arms are more common to break on the track than the street. Some say it's worn valve springs, but I have measured a large box of used springs varying in milage, and they are all within 1lb of each other.

It sounds like you have a fresh head only? No mention of rotating assembly, or engine size.

[i6mt6]

Yes it's got a scraper. I will confirm the oil pressure gauge. I'm not sure about what kind of bottom end work was done.

[e30davie]

"professionally built" just means the guy who did it has business cards. Reality is no-one can really comment on YOUR engine without taking it apart, measuring everything and putting it all back together.

Unfortunately its the nature of the game a bit, unless you do it yourself or you trust the actual guy with the spanner, who knows what you've got:)

If it runs alright and no weird noises, then thats a pretty good start. 1000 miles isn't very long, lets see how it is at 50,000 miles.

[jlevie]

No. Those modes have essentially no affect on reliability.

[TobyB]

At the risk of derailing this slightly, I'm not sure of the
value of the scraper. I have both a scraper (IE) and a
baffle, and unless I'm 3/16" over 'full', I lose pressure on
certain right- handers.
And yet, others with no scraper and the same baffle have no
problems. And yes, I've driven their cars. And watched the gauge in the same corners.
The next engine, I'm leaving the scraper out, just to see what happens,
in the 'it can't be any worse' department.

t
case study of exactly one, so far.
Well, unless you count 3 or 4 M10's...