Kent engine hours

[s800racer]

What counts as "hours" on an engine? Do you count 20 minutes of idling/warm-up time the same as track time? I've been counting 20 minute track sessions as .5 hours on the engine to account for warm-up, idle and drive back to paddock.

I've also heard varying opinions on when to rebuild - 40, 50, more?

If I were not as lazy as I am, I would be doing compression checks and leak-downs and if frogs had wings they wouldn't bump their butt when they jumped.

[reidhazelton]

I just counted on track time based on the session length. I figured the warm up time was immaterial. I didn't count for pit lane or false grid time either. I didn't care to be down to the minute.

For hours between rebuilds, I typically did a head refresh around 10 hours, and a bottom end around 30-40. I tried to time it so that the rebuild would be before the Runoffs so some times it was stretched a bit longer than it should. One time it had a slightly noisy cam bearing but it seemed consistent for a few weekends so I didn't worry about it. If you take good care of it, and don't miss shifts, it should last a good three to four years for most people on a bottom end.

My longest rebuild was about 45 hours on the bottom end. It sounded like a tractor with all the piston slap and other worn bits. That rebuild included a cam, pistons, rocker pedestals, a few valves, and all the other normal full-rebuild stuff and it ran me about $4,500 from the now-retired Curtis Farley. He said the crank and main bearings were fine (replaced anyway). From what I experienced, the ring lands and piston-to-cylinder clearance is what goes first. Then again, that was wringing mine to 7k pretty normally at RA so you might have different results.

[Daryl DeArman]

Any time it is running is creating wear. Engine wear can happen during cold start-up, at high rpms, at high temps, low-ish oil pressure coming in from a session. Just count all the hours. Leakdown and oil analysis combined with your engine builders' feedback/bill can give you an idea of just how many hours you want to go between rebuilds. Hour meters are very inexpensive.

My limited time with a Kent was pre-forged pistons and the better crank, so my experience would likely be very different than those racing a Kent today with regards to TBO.

[marshall9]

Get an hour meter

[TimH]

Ivey says he doesn't trust the timing chain past 75 hours. That could be a catastrophic failure.

[tstrong]

With forged pistons and new crank I have regularly run to 50+ hrs on the bottom end with no issue. And i always run to 7K and miss shifts now and then. With the new parts and The Ivey’s attention to detail lifecycle has been extraordinary. Todd

[Roland V. Johnson]

My current experience agrees with Todd 100% I do not count idle time. Running the engine hard at top revs is different than idling. I personally run the engine at around 2000RPM when warming it up to make sure the cam stays lubed. (watching it carefully to make sure you do not have excessive oil pressure) Others do not and just let the engine idle. Whatever works for you.

[TimH]

Hey Roland,

What do you consider excessive oil pressure? I see 60 PSI on cold mornings even at low idle.

[DanW]

Hey Roland,

What do you consider excessive oil pressure? I see 60 PSI on cold mornings even at low idle.

I have seen 50-60 on cold mornings too, running Valvoline racing synthetic 10w-30. I have 60+ on-track hours on the bottom end, 20 on the head. The real wear is to the timing chain,valve gear, rings, and piston ring lands.

Time for me to pull it out and send to Ivey.

[stonebridge20]

The real wear is to the timing chain,valve gear, rings, and piston ring lands.
.

Ever think about Cryo treating that stuff?

[billtebbutt]

Ever think about Cryo treating that stuff?

I can see how cryo would extend the lives of certain components, for sure. But when it comes to ring land wear, how would it help? I am assuming that ring land wear is caused by the ring being worked like a lever in the land every time the piston changes direction, eventually deforming the land and thereafter the ring starts wiggling around. Of course I could be wrong about my assumption!

thoughts?

BT

[Roland V. Johnson]

We have not had to replace many pistons since Jay Ivey had the new ones made. I consider 80+ excessive. I have seen 100+ on really cold start up in the past. I have seen what a blown up oil filter looks like.

[stonebridge20]

I can see how cryo would extend the lives of certain components, for sure. But when it comes to ring land wear, how would it help? I am assuming that ring land wear is caused by the ring being worked like a lever in the land every time the piston changes direction, eventually deforming the land and thereafter the ring starts wiggling around. Of course I could be wrong about my assumption!

thoughts?

BT

By tightening the grain structure and reducing induced stresses, the piston keeps it's shape better through the temperature range. This in turn reduces wear throughout the entire piston, including the lands. By Cryo treating the pistons, you can also run a little tighter on your clearances in turn reducing the amount piston rock because the piston doesn't "grow" as much in the bore.

A quick easy read for you Bill.

https://www.enginebuildermag.com/2017/03/big-chill-cryogenic-metal-treatment-benefits-may-not-visible-real/

[stonebridge20]

"The motor I am currently running has been fully cryoed so may get more time out of that one (thanks Mike)."

Quoted by John Robinson in another thread about one of his Kent engines.

Treadways engine,that ran for almost two complete laps (cool off and checkered flag) with no water in it at the 40th and the engine for the 50th were fully Cryo treated.

[DanW]

Ever think about Cryo treating that stuff?

Yes. How would I arrange that? Through Jay Ivey?

On edit: How about REM Isotropic?

Thanks.

[billtebbutt]

By tightening the grain structure and reducing induced stresses, the piston keeps it's shape better through the temperature range. This in turn reduces wear throughout the entire piston, including the lands. By Cryo treating the pistons, you can also run a little tighter on your clearances in turn reducing the amount piston rock because the piston doesn't "grow" as much in the bore.

A quick easy read for you Bill.

https://www.enginebuildermag.com/2017/03/big-chill-cryogenic-metal-treatment-benefits-may-not-visible-real/

That is an excellent article - thanks!!!!!

So less Ausenite, more Martensite is what we're after!!!!! Joking aside, the "eureka" moment for me was the description that cryo basically continues the quench part of the heat-treat cycle. Even I get that!

thanks again,
BT

[stonebridge20]

Yes. How would I arrange that? Through Jay Ivey?

On edit: How about REM Isotropic?

Thanks.

Dan, I'm sure Cameron can work out the logistics.

[stonebridge20]

That is an excellent article - thanks!!!!!

So less Ausenite, more Martensite is what we're after!!!!! Joking aside, the "eureka" moment for me was the description that cryo basically continues the quench part of the heat-treat cycle. Even I get that!

thanks again,
BT

Bill, what we have found is that crank grinding, block boring/honing, valve and seat work is best done prior to Cryo treatment.