threw another #3 rod, how to prevent this from happening again. Options

[crash914]

oil temp was elevated due to the rod bearing failure. symptom of low oil pressure at idle and temps of 220 oil temp.

normally I run around 180 degree oil temp and 30 psi pressure at idle.
Also running 100+ octane race fuel at 12:1 full throttle and about 9:1 compression.

[jd74914]

Thinking out loud here...Why are you running high octane fuel with a mild CR? With such low hours are your rings totally seated or are you pushing some fuel into the oil?

[yeahmag]

I had to rebuild two motors before switching to a dry sump due to rod knock. The CB Performance pump has pretty poor idle pressure, but is fine at anything about 1200 RPM. I did do a bit of work to open the ports in it...

Evan and I beat the piss out of the motor now (7000-7250 RPM) and it doesn't bat an eye.

[crash914]

actually my CR is higher, more like 10:1. I hate fuel knock. I would get some with running 93 so I just used 100 in this motor from the start.

How does the dry sump perform better if the oil is trapped in the heads and the issue is return flow? I guess you could tap a port in each head to help the return?

[HAM Inc]

Don't vent the heads. Oil pools in vented T4 heads. The higher the revs the more pooling.
https://newsite.hamheads.com/2016/12/10/typ...tests-analysis/

[crash914]

Good read. Thanks Len.

For things to note, I did see my dip stick extend after runs. Seems to indicate excessive crank case pressure.
I did have the heads vented to a breather box that drains back. The dry sump and no vents sounds promising.

[yeahmag]

I employed Lens and Jakes work on the current motor. Heads are not vented and a -10 AN welded to the chimney that leads to a breather tank.

[VaccaRabite]

Don't vent the heads. Oil pools in vented T4 heads. The higher the revs the more pooling.
https://newsite.hamheads.com/2016/12/10/typ...tests-analysis/

There used to be pictures of the test engine with modified valve covers with glass windows where you could see the oil pooling. Those pics were very convincing and had me pulling my head breathers out.

Zach

[HAM Inc]

Good read. Thanks Len.

For things to note, I did see my dip stick extend after runs. Seems to indicate excessive crank case pressure.
I did have the heads vented to a breather box that drains back. The dry sump and no vents sounds promising.

Herb, if you're just AXing then a dry sump system would probably be overkill. A lot goes into converting a wet-sump engine into a properly designed dry sump engine.

Keep the tuna can. Dump the head vents and add an Accusump.

As for the possibility of detonation, one easy tell-tale sign you can look for during disassembly is if top and second ring gaps have lined up. That's a classic sign of detonation.

[crash914]

Len, just so I am clear, plug the head vents, don't cross connect?

[GregAmy]

Totally taking this off-topic a bit further...last few races I experienced unhappiness with my 914 regarding vented rockers.

Last summer with my 2L I was taking a nice long left-hander at Thompson (under the bridge) and the pressed vent tube in the right head came out. Dumped shad-ton of oil all around the bend, causing a couple cars to spin and one to hit the wall (I strongly apologized and ensured he did not buy beer or dinner that night). Field-fixed it by slightly swaging the tube, tapping it back in tightly, and gooping it with silicon. Held for the weekend.

This September at the Lime Rock Labor Day historics, using a borrowed 1.8L. The valve covers have welded 1/2" tubes coming off the valve covers with oil hose secured by hose clamps. First session out, driving through Big Bend and the left hose came off the tube....dumping a shad-ton of oil all around the bend, causing myself and several other cars to spin (no contact, thank goodness). Field-fixed by cleaning it all up, screwing it on as tight as I could, then drilling a hole across the hose, clamp, and tube and putting in a cotter pin, sealing it with silicon. Held for the rest of the weekend.

I'm also running a CB Performance dry sump pump.

I'm really getting tired of that. If I don't need these rocker vents then I'll just drill/tap/plug the holes on the 2L engine I'm building now and be done with it.

[iankarr]

Curious...could unbalanced components accelerate the bearing wear and lead to this sooner?

[HAM Inc]

Len, just so I am clear, plug the head vents, don't cross connect?

Yes. Just plug them.

Basic engine theory: Place the oil sump pick up at the engines lowest point in the crankcase and vent the crankcase at its highest point. Keep it simple.

[HAM Inc]

Totally taking this off-topic a bit further...last few races I experienced unhappiness with my 914 regarding vented rockers.

Last summer with my 2L I was taking a nice long left-hander at Thompson (under the bridge) and the pressed vent tube in the right head came out. Dumped shad-ton of oil all around the bend, causing a couple cars to spin and one to hit the wall (I strongly apologized and ensured he did not buy beer or dinner that night). Field-fixed it by slightly swaging the tube, tapping it back in tightly, and gooping it with silicon. Held for the weekend.

This September at the Lime Rock Labor Day historics, using a borrowed 1.8L. The valve covers have welded 1/2" tubes coming off the valve covers with oil hose secured by hose clamps. First session out, driving through Big Bend and the left hose came off the tube....dumping a shad-ton of oil all around the bend, causing myself and several other cars to spin (no contact, thank goodness). Field-fixed by cleaning it all up, screwing it on as tight as I could, then drilling a hole across the hose, clamp, and tube and putting in a cotter pin, sealing it with silicon. Held for the rest of the weekend.

I'm also running a CB Performance dry sump pump.

I'm really getting tired of that. If I don't need these rocker vents then I'll just drill/tap/plug the holes on the 2L engine I'm building now and be done with it.

Greg you don't need anymore oil incidents! Your last one ought to hold you for the rest of your driving career. (IMG:style_emoticons/default/happy11.gif)

[yeahmag]

Greg,

Just make sure that you increase the chimney vent some. I went with a -10 AN weld-in bung and a catch can to ensure good breathing.

-Aaron

[GregAmy]

Greg you don't need anymore oil incidents! Your last one ought to hold you for the rest of your driving career. (IMG:style_emoticons/default/happy11.gif)

Jeebus! That's not even considering that one!!! Toss in the "putting the Super Touring car on its lid" in early 2018 and it's been an "interesting" 18 months...I really do need a boring hobby...

Fantastic meeting you and your dad at VIR. Hope that happens again soon.

I think I'm'a gonna plug those head holes.

[GregAmy]

Just make sure that you increase the chimney vent some. I went with a -10 AN weld-in bung and a catch can to ensure good breathing.

That shouldn't be a hassle. I've modified the "stack" there to both vent and accept drainback from the can (kinda see it in this photo); it would be easy to toss in a larger vent tube on that block-off plate.

[HAM Inc]

Greg you don't need anymore oil incidents! Your last one ought to hold you for the rest of your driving career. (IMG:style_emoticons/default/happy11.gif)

Jeebus! That's not even considering that one!!! Toss in the "putting the Super Touring car on its lid" in early 2018 and it's been an "interesting" 18 months...I really do need a boring hobby...

Fantastic meeting you and your dad at VIR. Hope that happens again soon.

I think I'm'a gonna plug those head holes.

Damn Greg! You've had a hell of a year and a half. That VIR shit was scary and such a suck ass way to end up considering how hard you guys worked to make the race.
The NOLA "Jackie Stewart" commentary is gold! I have to ask, how did you handle the post race de-brief with the dive-bomber? Was a jack handle involved?

Dad and I had a really good time at VIR. We sure did appreciate the passes and we enjoyed meeting your guys. Wish we could have socialized more. Maybe next time you won't have to work so hard!

[GregAmy]

The NOLA "Jackie Stewart" commentary is gold! I have to ask, how did you handle the post race de-brief with the dive-bomber? Was a jack handle involved?

Oh, it did not go well AT ALL. The short version is I was tossing paper as I was climbing out of the meat wagon, and when the SOM decision went against him, he and his dad yelled and cursed at the stewards and flipped them the bird. Then started yelling at us, claiming we were damaging his chances for his future racing career. At the time it was kinda surprising; in hindsight it's freaking hilarious.

I DO NOT like thrashing at the track (or, really, at home). But I seem to surround myself with people that are all like, "dude, we're here, let's fix that s**t" and it makes for good stories. I need more less-motivated friends.

But last weekend at NJMP was nice: good weather, 914 ran all weekend without a hitch, boring video, pretty car goes back on trailer as pretty as it was when it arrived. Need more of those. (IMG:style_emoticons/default/wink.gif)

Now to decide what to do in 2020. I am becoming more attracted to that limited prep HProd 1.8L option...know anyone that could build a Micro/Megasquirt using the stock throttle body...?

Back to our regularly-scheduled "toss a rod" discussion. In that vein, here's what happened to me the weekend before the Lime Rock Historics 2019 (remember what I said about needing to be more boring...?)

Knitting. That's the ticket. Or crochet or quilting. Though they get pretty serious about that stuff...

[rick 918-S]

I can't think of a motor with nearly a 4" bore that turns more than 6k.

(IMG:style_emoticons/default/agree.gif) check your connecting rod ratio to assist in cakculating you approximate RPM range. The long rods should allow for higher RPMs but the size of the Piston may be causing the inertia to jerk the bolts apart.

My BMW 2002 had a con rod ratio of 1.6875 which translates to 6875 RPM's at an extended 7200 the harmonics and piston inertia would pull the rod bolts apart. Ok for short bursts but really a grenade waiting to happen.