[Race_Prep] Never Ending Race Car Build

[petert 585]

Now right on the limit of the bar mount. Probably time to move on to a custom bar/front.

[petert 585]

Threw a rod today.

[Andy 105 1 Cars]

Oh. That is a real disappointment . Full engine rebuild required with replacement block and heaven knows what else. However, you must have been trying hard !

[petert 585]

Well that's the strange thing. It was just went bang changing from 2-3 at 7500. My son was driving, just 8 laps in, out of a 137 lap endurance race. Suffice to say I didn't get a turn.

[petert 585]

Sorry, it was 3-4. Looks like he got a bit flustered trying to shut it down.

 

 

[Andy 105 1 Cars]

See what you mean. Good video clip though. The engine sounded great right up until it popped a rod though its crankcase . I suppose that is the thing about some modes of failure. A component goes through a certain number of stress cycles and then fails on the next cycle , even though the stress is no higher than the previous x thousand of them . Still a complete bummer though. 

[wicked 103 3 Cars]

Always crap to see a good block popping rods... feel sorry for you.

Any clue on the cause? It popped on straight and not in a left corner. Looks like the rod bolt snapped?

[mmt 15]

So sorry to hear Thatcher bad noise. Sounded really healthy before. 7500 rum for 130 Lars must be tough though. Some good lines your son makes. 

[petert 585]

Boom! I think the engine gave birth to an alien. If it's only got two bent valves I'll be extremely lucky.

[JeffR 51]

Bloody hell. Some serious damage there.

[petert 585]

Autopsy complete. I suspect the cap from conrod #3 broke in two, as there is only part of it remaining. The two rod bolts snapped, remains of which are still in the main part of the rod. The remains of the two bolts and large part of the cap are missing. The engine kept rotating, maintaining oil pressure, until John shut it down. The crankshaft is in surprisingly good condition and should survive a regrind, thank goodness. Piston #3 is cracked (circled) and has substantial bruising (circled) where it has been smacking into the head. Mains bearings and remaining three rod bearings were perfect.

 

What do I build next?

[wicked 103 3 Cars]

26 minutes ago, petert said:

 

What do I build next?

 

 

 

Rebuild what you had if you have spare parts or maybe move on to EW10J4S?

 

 

 

[welshpug 1,656]

why did the cap and bolts break though?   seized / spun bearing?

[petert 585]

Look at #3 rod journal. Other than a few dings, it's perfect. The remaining bearings are perfect, indicating there was oil pressure until it was turned off.

[Andy 105 1 Cars]

So not a bearing failure. Back to a rod failure then . Slightly disappointing given that you clearly went to the expense of fitting forged steel rods to avoid such difficulties . As we say in this part of the world........ bugger

 

[wicked 103 3 Cars]

1 hour ago, welshpug said:

why did the cap and bolts break though?   seized / spun bearing?

If the bearing had spun, the crank journal would have more damage imho.  Think the cap was done with the continuous high revs... 

Edited February 23, 2018 by wicked

[Batfink 201]

On 02/02/2018 at 10:12 AM, petert said:

I've made the decision to jump from 205x50/15 to 225x50/15. The difference in diameter is the real killer. I have to perform considerable body work to make them clear the front bumper bar when running 6 deg of caster. I'll post some pics over the weekend.

 

Additionally, the difference in diameter is 3.5%, equivalent to half a cwp change!

Having just aborted trying to do the same. The size difference is huge! I could not get the suspension geometry good with a low ride height. Also the scrub radius was looking nasty.
This was with Pirelli tyres but the difference was 11mm in ride height.

Good luck with the engine!

[petert 585]

We got through two Practice sessions, Qualifying and eight laps on the 225's. I really think it was over tyred. I might try 215x50/15 next. Our cars aren't that low. We've had more success with a higher ride height and getting the diagonal weight distribution correct.

Edited February 27, 2018 by petert

[petert 585]

The pan and scrapers I can repair/rebuild. However the pump needs a new scavenge stage.

[petert 585]

After many hours of fitting, fettling, cams in, cams out, etc., I'm finally ready to assemble our big head. It features long stem oversize valves, Z1000 collets, Supertech SPR-H1022D double springs, Z1000 titanium retainers, open 33mm buckets and no shims.

[Andy 105 1 Cars]

Impressive. No shims. Please explain . Have you ground each valve stem to the exact clearance ?

 

[petert 585]

Yes and no. A combination of seat cutting, base circle changes etc. meant the shims would have been 1mm or less. I was able to source buckets with thicker pads which made up the difference. It was very fiddly and time consuming but worth the effort.

[Andy 105 1 Cars]

I see. That must have been a job . Getting each one exactly right must have meant many iterations. Impressive 

[petert 585]

Well, it's been a long time between posts on this project. Bad health and family issues have dominated my last 12 months. Here's the piston and rod assemblies for the new engine race engine. Hopefully I won't see them again for a long time.

[B1ack_Mi16 67]

What make of rods is this?