newbie with a clio cup race car

[ian-speedy]

Uploaded the incar video onto youtube , I have used windows movie maker and the quality if crap !

http://www.youtube.com/watch?v=fCEsp1wUVqk

 

[Tony Hunter]

Ouch, that did just die.

 

[Chip-mk1]

Very undramatic but very sudden.

 

[Sandy309]

If the rod is blue it has suffered oil starvation. Steve

Agree.

I don't think bolt failure would be primary in this case and "bolt failure" with these budget rods is usually a mis-diagnosis of the cap splitting, due to the poor design/manufacture around the bolt seat creating a stress point. The broken bolt(s) always bent, which indicates bending failure rather than tensile/crack.

 

[Sandy309]

Here are a couple of examples, on the left is a British made good quality rod (Robson for 1600 Zetec SE), with untagged bearings that span after oil pump failure and the driver kept going back to the pits. The rod stretched and bolts bent, but didn't fail, because the cap held together.
On the right is the centre peice of the cap of a Catcam rod (for 106 GTI "Kitcar", similar design to PEC and I've seen the same with PEC rods) that was a straight fatigue failure after a couple of seasons, no significant overring and the bearing surface was still evident, so no oil starvation. The failure is clearly at the stress point around the bolt head counterbore where there's a hard corner, rather than the gentle buttress of a better rod design.

 

[ian-speedy]

I have just ordered a new set of rods bolts and pistons from PEC , but upgraded the bolts to the new stronger ones just in case , so hopefully get it back up and running soon as , so those in the know , what oil pressure should I be running at a minimum considering the use , was looking over my in car video's on youtube , and the first rally I did with this engine it was running under 3 bar oil pressure , the weekend it was just over , seems a bit strange it can change ?? have been running the same oil although its had 2 changes , running Castrol Edge 10/60 , have always run this in all my cars

This is the centre mains

No 2 main

No 3 big end

No 2 big end looking rather second hand

Must have run for a while damaged as its sucked up the bearing leftovers into the pick up

​

 

[Chip-mk1]

Can you post a picture of the back of the centre main?

as for oil pressure. Have you got temp data too? Variation in temperature is common reason for pressure changing.

 

[ian-speedy]

the second photo is both shells from the centre main

 

[Porkie]

Sandy, my new engine has one of your porno exhaust manifolds on. So if this fourth one blows up. Its 1000% your fault

 

[Chip-mk1]

the second photo is both shells from the centre main

Yes, the bearing face of both, can you post a picture of the back of both.

 

[ian-speedy]

 

[Chip-mk1]

Looks like its not the cause like I was expecting then, as would be more worn than that if it was the first thing to go.

So looks like the rod was the cause probably.

 

[ian-speedy]

even the revs i'm using ? hard cut at 7600

 

[Kenny.s]

The surface of the centre main looks like it's suffered from fatigue failure. If it was just shrapnel that had gone through it, it would be heavily scored but there are two distinct areas on the cap shell that have started to break away.
It's possible the big end that failed suffered the same thing but the resulting break up of the bearing caused it to go tight.

What make of bearings are they?

If the rod was the route cause it wouldnt be discoloured though? it would just have snapped

 

[ian-speedy]

The rod has broken in the same place where that Cat rod has broken in Sandy's photo , but you can clearly see mine has has a hell of a time before letting go !

just had a phone around and have ordered a set of Arrow rods so will cancel the order for the PEC rods and just use the Wossner pistons I have ordered from them now , rather be safe than sorry

 

[ian-speedy]

I bought ACL bearings , can't remember if they were both sets or just the big ends , sure Fred will know

 

[Kenny.s]

Was everything balanced?

Do any of the other bearings have any signs of fatigue failure? Might be a vibration/harmonic issue after all, but can also be caused by detonation although thats more likely on the big ends than the mains.

 

[Chip-mk1]

even the revs i'm using ? hard cut at 7600

Sorry Ian, was typing on phone and being lazy, when I said the rod being the cause I meant the bearing in the rod spinning first rather than the bearing on the centre main spinning first.

 

[Chip-mk1]

Was everything balanced?

Do any of the other bearings have any signs of fatigue failure? Might be a vibration/harmonic issue after all, but can also be caused by detonation although thats more likely on the big ends than the mains.

For the bearings to be damaged by det I would have expected the pistons to tell the tale as well, do we have pictures of the top of them?

 

[ian-speedy]

photo above of one of the other mains and big end , some marks but nothing like the centre one , no signs of detonation , but after having it dynoed and tuned in the car on the rollers and road I wouldn't expect any

 

[Sandy309]

Sandy, my new engine has one of your porno exhaust manifolds on. So if this fourth one blows up. Its 1000% your fault

Fair enough

This is getting a bit into clutching at straws, because without seeing everything together, in detail; observing this is not a whole picture. The pick up may already have been choked before the ultimate failure and provoked it, that's a common cause of oil starvation in any engine, so the detailed stack of material in there needs to be analysed. The middle main to me looks like it may have started as a fatigue failure to be honest; with the delamination of the material, which would usually be crank vibration combined with continuous high rpm.
As regards bolts, high grade bolts should always be used in these engines IMO, you have a steep thrust angle and long stroke with correspondingly high peak piston speeds. To take the comparison above with the BDA, specs vary, but typically BDAs used 77mm stroke with 132.5mm rod and the F4R standard design is 93mm with 144mm rod. The F4R has a low rod:stroke ratio of 1.55, which is about as far as you can sensibly go and gives a maximum rod thrust angle of 18.8 degrees, compared to 16.8 for the BDA example. If you take peak values for the F4R at 8000rpm, the BDA won't match the piston acceleration until 8950rpm, the peak piston speed won't match until a heady 9750rpm! Hopefully this goes some way to illustrating how hard the F4R bottom end has to work in competition use and how poorly suited it is to being revved (before even discussing the top end!)

 

[Chip-mk1]

photo above of one of the other mains and big end , some marks but nothing like the centre one , no signs of detonation , but after having it dynoed and tuned in the car on the rollers and road I wouldn't expect any

Detonation isnt always a tune issue, can be a sensor failure issue, or injector issue, or fuel swirl pot issue etc, so just because its well tuned doesnt always mean it wont suffer det as a result of other factors.

 

[Kenny.s]

Detonation isnt always a tune issue, can be a sensor failure issue, or injector issue, or fuel swirl pot issue etc, so just because its well tuned doesnt always mean it wont suffer det as a result of other factors.

Just what I was about to type!

Does the ecu have any sort of knock detection?

 

[Chip-mk1]

photo above of one of the other mains and big end , some marks but nothing like the centre one , no signs of detonation , but after having it dynoed and tuned in the car on the rollers and road I wouldn't expect any

The fact that more than one bearing seems to have suffered failure at once, certainly seems to point to some other underlying issue, like either a harmonics/vibration/flex issue going along the crank/block or a problem with oil supply that saw both get starved of oil.

Quite hard to tell from just a few pictures though and TBH even with the parts all laid out I suspect that you wont ever get a definitive answer.

 

[ian-speedy]

Detonation isnt always a tune issue, can be a sensor failure issue, or injector issue, or fuel swirl pot issue etc, so just because its well tuned doesnt always mean it wont suffer det as a result of other factors.

no we have no knock detection , looking at the head and pistons there is no evidence of det though

 

[Chip-mk1]

Fair enough

This is getting a bit into clutching at straws, because without seeing everything together, in detail; observing this is not a whole picture.

Agreed, and even with the whole lot in front of you its still really hard to tell if a pump caused a bearing to fail or if a bearing caused a pump to fail via oil starvation at the pickup etc as they are so good at taking each other out.

The pick up may already have been choked before the ultimate failure and provoked it, that's a common cause of oil starvation in any engine, so the detailed stack of material in there needs to be analysed. The middle main to me looks like it may have started as a fatigue failure to be honest; with the delamination of the material, which would usually be crank vibration combined with continuous high rpm.

Yeah the centre main has definitely started to fail and looks like not from swarf damage, so if the rest of the engine had survived a bit longer, it looks like the centre main would have killed it anyway. (as is common on these engines)

As regards bolts, high grade bolts should always be used in these engines IMO, you have a steep thrust angle and long stroke with correspondingly high peak piston speeds. To take the comparison above with the BDA, specs vary, but typically BDAs used 77mm stroke with 132.5mm rod and the F4R standard design is 93mm with 144mm rod. The F4R has a low rod:stroke ratio of 1.55, which is about as far as you can sensibly go and gives a maximum rod thrust angle of 18.8 degrees, compared to 16.8 for the BDA example. If you take peak values for the F4R at 8000rpm, the BDA won't match the piston acceleration until 8950rpm, the peak piston speed won't match until a heady 9750rpm! Hopefully this goes some way to illustrating how hard the F4R bottom end has to work in competition use and how poorly suited it is to being revved (before even discussing the top end!)

Yeah the internal geometry with such a long throw crank and such a poor rod angle makes this a terrible design of engine for doing high RPM N/A work, they are actually far better suited to having a turbo hung off them and making lots of midrange really if you want power than trying to rev them but sadly Ian's class wont allow that!

 

[Chip-mk1]

no we have no knock detection , looking at the head and pistons there is no evidence of det though

I dont think it will be det doing that to the centre main TBH, although I understand Kenny's thought process.

 

[Kenny.s]

I dont think it will be det doing that to the centre main TBH, although I understand Kenny's thought process.

I doubt it's Det either TBH, as mentioned earlier far more likely to see that on the big ends.

 

[steveboyslim]

Ian,

Do you have any oil temperature data ?
Not quite the same but from what I have been told hot oil pressure can be very low (at idle) after a track day session.
Looking at the video possibly oil surge, with the sharp left, then left and then down hill on a trailing throttle (hot oil giving at a lower pressure) before it went bang.
Dry sumped will be the way forward with your engine with the steel crank.

Steve

 

[Fred@BTM]

can we stop banging on about crank flex and block flex! Its only reving to 7600 (although it does that a lot LOL!!!)

 

[ian-speedy]

no we don't have any data , it didn't feel right at around 5.10 into the stage , and you will see me just back off a bit , I had a quick look at the dash , nothing obvious then carried on hard from the 2nd gear right by the armaco , I don't think it was oil surge in those series of bends , the cornering forces are nothing like track use , and I was on wets as well for the first loop so wasn't digging in as well as it would on slicks

 

[Chip-mk1]

can we stop banging on about crank flex and block flex! Its only reving to 7600 (although it does that a lot LOL!!!)

As Sandy mentions, even at 7.6K these engines have internal speeds higher than a lot of other engines do well into the 8s

 

[Fred@BTM]

yeah its a stupid engine, but some of the posts on here make it sound like every F4R with a raised rev limit is about to explode which simply isn't the case!

 

[EVOgone]

Well its an engine week.! After a full top end rebuild for F7R engine (after 3 season without a single issues 240bhp and rev to 8k all day every event) for its last event in the pink car we decided to put some new shell in whilst the engine was out and goes in the new car. But we notice quite a lot of end float in the crank..!!! Only to find when the sump was off the thrust washer there and the end of a oil sprayer from no.1 !!!! Engine ran brilliantly and never had an issue before we took it out so lucky from the that point but the crank and block are scrap as there is no thrust surface left.! All bearing were mint but did notice some lateral lines on the inner surface rod caps.

Anyone got a F7R bottom end lying about....

 

[Fred@BTM]

It just so happens i do have an F7R bottom end LOL

 

[ian-speedy]

PEC sent out the pistons rods and bearings before I could cancel the rods , so had them delivered yesterday , and the Arrow rods I ordered yesterday turned up this morning , you can see the difference in quality and machining when they are side by side , but then at £860 just for the rods you should do lol , it cost just as much for the rods as the Wossner pistons , PEC rods , upgrade to the new stronger ARP rod bolts , and ACL big ends !

 

[Chip-mk1]

Good choice on the arrows, really good quality product.

 

[mi16chris]

I've had problems with pec rods before there not great tbh great up grade with the arrows

 

[steveboyslim]

PEC sent out the pistons rods and bearings before I could cancel the rods , so had them delivered yesterday , and the Arrow rods I ordered yesterday turned up this morning , you can see the difference in quality and machining when they are side by side , but then at £860 just for the rods you should do lol , it cost just as much for the rods as the Wossner pistons , PEC rods , upgrade to the new stronger ARP rod bolts , and ACL big ends !

What grade are the ARP bolts in the Arrows compared with the PEC, are they the same ?

Steve

 

[Fred@BTM]

those PEC's are wrong anyway, non tagged