ZRP Forged Conrods
Discussion
e30m3Mark said:
In truth, there was also some breakdown and/or miscommunication which is why I'm taking a more philosophical stance than maybe I would otherwise. As you say though, as a customer with little knowledge one is dependent on the expertise you're paying for.
I'm sensing there is more to this than meets the eye, I have a degree in customer psychology 
That aside, if there are really oilers missing then I would be taking it up with ZRP, their pic shows them. Were they missed off or not, do they usually come with them?
Quite what you'd achieve I don't know, probably not a lot and they'll likely play the 'it's just a generic picture' card as it isn't listed in their spec.
If the motor has overheated then it could have suffered from det', this hammers small end bearings on some engines.
227bhp said:
I'm sensing there is more to this than meets the eye, I have a degree in customer psychology
Your spider senses are correct. 
I had a quick look at their website and their warranty is pretty flimsy. It's also only 30 days long and would be negated by the overheat anyway.
All I can say with any certainty is, that with the benefit of 20/20 hindsight, I would have gone with Arrow or shot peened and balanced my OE rods.
227bhp said:
stevesingo said:
Stock BMW S14 rods don't have an oil way from big end to little end, nor do my Arrow S14 rods.
If the ZRP rods had been inspected for dimension conformity- roundness, size, etc, of big and little ends, and face of the clamp face and under the head bolt face, something may have come up as being sub-optimal. If it didn't, having the info prevents the was it-wasn't it umming and arhhring.
BMW Motorsport up until the end of 1991 were using lightened and balanced stock roads with uprated bolts in GrpA with engines running 9000rpm.
They must have some oiling hole in the rod? It's usually a drilling for splash feed, not the rifle drilling you mean.If the ZRP rods had been inspected for dimension conformity- roundness, size, etc, of big and little ends, and face of the clamp face and under the head bolt face, something may have come up as being sub-optimal. If it didn't, having the info prevents the was it-wasn't it umming and arhhring.
BMW Motorsport up until the end of 1991 were using lightened and balanced stock roads with uprated bolts in GrpA with engines running 9000rpm.
If you go back to P1 and click on the link it shows one in the pic (with oil hole).
The builder was given the rods to examine and he passed and fitted them, he can't really go back now and point out they are substandard. IF there are holes missing then he should have noticed, it's an hours job to drill some in. The buck stops with the builder, not the components, that's what you are paying him for.
That's the problem when you are the customer with little knowledge (and little interest and memory) you take what's given, people will always blame something else as a get-out-of-jail-free card when an expensive failure occurs.
Maybe Mark has his stock rods to hand to check those.
stevieturbo said:
If there was an inherent design fault with the rods....then everyone using them would be having failures.
There appear to be a few posts / threads that talk of an inherent design flaw in relation to small end oil feed. All I've done is a brief online search though, so am not in a position to give more detail than that. I'm not suggesting everyone using them will have failures though. Just that there is probably good reason to perform or request more thorough checks?Mignon said:
You don't explain what actually failed here or why it might be the conrods partly at fault. However if after I gave such a detailed list of what to check you still didn't have little end oil holes machined in if those were lacking then it seems I wasted my time.
I simply don't have the knowledge to be able to give a more detailed explanation. I did take note of your previous post though and did make the builder aware, but I have no engineering background myself so as said earlier, am dependent on others. It is partly for that reason I updated this thread though, so at least anyone else considering these rods can do so knowing potential risk. The info / advice you kindly posted also remains for others so I don't think it was a waste. It has been an expensive lesson, but a lesson all the same.The link in the first post in this thread to the ZRP website says the rods have a radial groove in the little end bushings. That should suffice perfectly well for oiling.
Let me be clear about how conrods have oil supply built in.
On press fit gudgeon pins there is no need for little end oiling. The pins don't rotate in the rods. You will however always see that pistons have an oil hole in the pin bosses to lubricate where the pin rotates in the piston.
On floating gudgeon pins there MUST be an oil supply to the little end bearing. This can be done by either drilling a 3mm hole with a big chamfer into the very top of the little end right through into the bushing or by machining a radial groove into the bronze bushing itself.
It is common on stock rods to have an oil drilling from the big end bearing to the top side of the big end on the rod. This is to squirt oil to the underside of the piston crown and the bores for lubrication and cooling purposes. It is debateable how much this achieves given the amount of oil thrown up by the crankshaft anyway.
Let me be clear about how conrods have oil supply built in.
On press fit gudgeon pins there is no need for little end oiling. The pins don't rotate in the rods. You will however always see that pistons have an oil hole in the pin bosses to lubricate where the pin rotates in the piston.
On floating gudgeon pins there MUST be an oil supply to the little end bearing. This can be done by either drilling a 3mm hole with a big chamfer into the very top of the little end right through into the bushing or by machining a radial groove into the bronze bushing itself.
It is common on stock rods to have an oil drilling from the big end bearing to the top side of the big end on the rod. This is to squirt oil to the underside of the piston crown and the bores for lubrication and cooling purposes. It is debateable how much this achieves given the amount of oil thrown up by the crankshaft anyway.
227bhp said:
The problem is your claims have no facts to back them up - at all, so are pretty pointless.
This is why PH have a no name & shame rule.
Sorry - I should have been clear about fact that I'm not looking to name / shame anyone. I'm simply relaying my experience and suggesting that anyone in a similar position (looking at having an engine rebuilt) be more vigilant about parts quality, tolerance etc than maybe I was. I was probably a little naive in my expectations of some people and maybe too reliant on others without making my expectations clear? This is why PH have a no name & shame rule.
I'm grateful to those that have taken time to respond here though, as I certainly know a bit more about the subject than I did.
I genuinely feel for you. I hate engines dying and am always saddened to hear of failures. It is both mentally and financially distressing. These cheap rods may be fine but we come across a fair few failures which may well be the rods at fault; not looking for a grand ph argument here, just expressing my personal opinion as a tuner who works with many folk and receives a lot of woe and advice request emails from all around the globe. The cheap rods seem to be a common factor associated with failure especially on race engines. We will not fit the cheap rods; we have handled them, measured them, compared them and do not feel at all comfortable with them. If we do not fit good quality (imo) rods we carefully check OE ones and fit ARP bolts in the comp engines.
Peter
Peter
I'm building a pontiac at the moment with some new but crap interference rods. 6 pistons were assembled by hand with a modest amount of heat. The other 2 don't want to know even with a press. I'm having everything measured today to see what the 'interference' is and whether everything straight. It's a flipping PITA.
I put ZRP rods in a Honda K20 build.
The little end has a radial oil groove and a hole from the outside to this groove in the bushing.
That looks not really any different from the Honda OEM rods of the K20. Similar groove and hole.
My former supercharged Rover K has chinese rods with the same features and had no oiling issues whatsoever.
They are in there for 10 yrs now and I have checked bearings and the inside while developing/fixing the engine over the years.
I used up to 1 bar of boost and up to 7800 rpm. And yes, I did not catch fire and it sucessfully finished more than a dozen trackdays.
If you cooked the BMW engine for a lack of oil or coolant or pump failure or whatever, it is very hard to say the rods were at fault.
Once severely overheated or running with insufficient oil pressure for even a second, things get VERY hot very quickly and distort.
A engine block that overheats distorts/deforms and with it the main bearing clearances change. Easy to spin a bearing.
Oil that is too hot may lead to insufficient oil film thickness. Bearing failure with subsequent local overheating is then not far away.
Even the most expensive rods for thousand of pounds a set would have likely suffered the same fate.
The builder should measure the rods for clearance and roundness. He should measure bearing clearance and confirm with a secondary method such as plastigauge. The ZRP rods are not made from cheese. Unless you cook the engine, their big end won't turn square all of a sudden by itself.
I'd not blame ZRP for that failure just like that or even speculate that it has to do with the rods. The mentioned "unrelated" cooling issues are more of a strong hint where the bearing or rod failure stems from.
People read the interwebs, find the brand name and word failure within one thread and conclude the product is inadequate. They do not read the entire thread or even if, commonly do not understand it. I'd say this is unfair towards the vendor or builder.
I also got ZRP's crank and the dimensions very exceptionally uniform across the journals for crank and rods.
The Honda main bearing tunnels and crank journals showed much bigger variation than the aftermarket parts.
The OE parts were well used, though.
The little end has a radial oil groove and a hole from the outside to this groove in the bushing.
That looks not really any different from the Honda OEM rods of the K20. Similar groove and hole.
My former supercharged Rover K has chinese rods with the same features and had no oiling issues whatsoever.
They are in there for 10 yrs now and I have checked bearings and the inside while developing/fixing the engine over the years.
I used up to 1 bar of boost and up to 7800 rpm. And yes, I did not catch fire and it sucessfully finished more than a dozen trackdays.
If you cooked the BMW engine for a lack of oil or coolant or pump failure or whatever, it is very hard to say the rods were at fault.
Once severely overheated or running with insufficient oil pressure for even a second, things get VERY hot very quickly and distort.
A engine block that overheats distorts/deforms and with it the main bearing clearances change. Easy to spin a bearing.
Oil that is too hot may lead to insufficient oil film thickness. Bearing failure with subsequent local overheating is then not far away.
Even the most expensive rods for thousand of pounds a set would have likely suffered the same fate.
The builder should measure the rods for clearance and roundness. He should measure bearing clearance and confirm with a secondary method such as plastigauge. The ZRP rods are not made from cheese. Unless you cook the engine, their big end won't turn square all of a sudden by itself.
I'd not blame ZRP for that failure just like that or even speculate that it has to do with the rods. The mentioned "unrelated" cooling issues are more of a strong hint where the bearing or rod failure stems from.
People read the interwebs, find the brand name and word failure within one thread and conclude the product is inadequate. They do not read the entire thread or even if, commonly do not understand it. I'd say this is unfair towards the vendor or builder.
I also got ZRP's crank and the dimensions very exceptionally uniform across the journals for crank and rods.
The Honda main bearing tunnels and crank journals showed much bigger variation than the aftermarket parts.
The OE parts were well used, though.
Edited by Ive on Friday 10th November 15:22
Edited by Ive on Friday 10th November 15:25
As I said, I am/was not seeking to lay blame solely at ZRP's door. Simply passing on my experience and comments made by the engine builder. As you rightly say, the overheating most likely started a chain of events. That said, the builder also stated their was a flaw with the little end / oil way but that is just his opinion I guess?
Apologies if my lack of knowledge is a frustration but my hope was that I might learn something through discussion.
Apologies if my lack of knowledge is a frustration but my hope was that I might learn something through discussion.
"builder also stated their was a flaw with the little end / oil way but that is just his opinion I guess"
This would still raise the question why the builder put them in in first place?
We would all love to see pictures of the failed components. This would help everybody besides being very interesting from a technical standpoint.
The failed engine parts are still your property. I would collect them from the builder and take pictures.
You might even ask ZRP for their opinion. I found Drakos Engineering, the ZRP distributor, very responsive.
Send them some pictures first and if they request it to check for a refund or other mitigation, even the parts for inspection.
There are some very experienced folks here. it might even help you finding the root cause of the issues.
This would still raise the question why the builder put them in in first place?
We would all love to see pictures of the failed components. This would help everybody besides being very interesting from a technical standpoint.
The failed engine parts are still your property. I would collect them from the builder and take pictures.
You might even ask ZRP for their opinion. I found Drakos Engineering, the ZRP distributor, very responsive.
Send them some pictures first and if they request it to check for a refund or other mitigation, even the parts for inspection.
There are some very experienced folks here. it might even help you finding the root cause of the issues.
e30m3Mark said:
A quick update.
Although all was well for a while, a couple of cooling issues contributed to an eventual failure. 20/20 hindsight is a wonderful thing but I wouldn't use ZRP rods again.
After months of searching the web generally to see if there were reports of ZRP failures or problems this is the only one that kind of does, yet I think the comment is unfair from reading the other input, and the lack of photographic evidence, and the statements repeated that the builder should have checked this. Although all was well for a while, a couple of cooling issues contributed to an eventual failure. 20/20 hindsight is a wonderful thing but I wouldn't use ZRP rods again.
I think this poster is avoiding saying the same about his engine builder, and should retract the ZRP comment here, in this thread, as exactly the point made before, others may read it and conclude incorrectly that a product is poor.
Now, I have these rods, for an R53 Cooper S. The rods are up spec'd to include ARP L-19 bolts over ARP2000, and they do have a groove in the small end bush. They have a vertical hole right through the top of the small end and bush. They have no hole through the top side of the big end but this engine has oilers.
I have one criticism, which I mailed Alex Drakos over, and I'm going to show it here because I think it unusual, and to me it doesn't make sense frankly. Alex Drakos referred my question to his engineers and came back to me saying to go ahead and fit them, also a local engine builder said to use them, but here is my question..... the bearing tang, on any rod I have ever seen, butts up to a closed face of the end cap or rod if the opposing side. These rods have double tangs machined in which is nice if choosing a similar bearing, however they are mated to those of the other half (rod or cap) instead of opposite. Yes the caps are the correct way round, (also if they are the wrong way there is a significant offset in my opinion) and it just made me think there is little to prevent the bearing from rotating should it pick up. I know crush is designed to stop this but what are the tangs for if not to prevent such rotation? These appear like a little ramp for the opposing tang to ride up if you see what I mean. Let me know if I worry for no reason?
As for quality, on the face of it these appear excellent. They seem to be in use for VW/Audi and are mentioned for Subaru in stroker kits, so I believe the brand has some recognition. Now I know builders and some customers like what they like, but putting a newish brand like this down inappropriately, especially to save face of their own or a builders oversight, needs correction. I'm not yet a fan of this product, and I only happen to be in ownership of them as somebody local to me bought them in this spec for an R56S build and was told they were for the earlier car, he'd had them balance checked, and I stepped in and took them at a fair price believing from my own research they could be good for a very strong engine circa 300hp and up to 10k rpm.
Yesterday some Wossner pistons arrived. I was uncertain whether I'd bother with these as the OE are forged and may be fine, but these are specialist, so I went ahead. An interesting thought of course was how well the pins supplied with them, fit the ZRP rods. I gently offered one up and there was some resistance but I could feel it was so close to the right size. The rods were cold, and after a couple of minutes handling, the pin just slid in place, no rock.
Unbelievable really that such light and little things are key components in how these cars can perform, they look so tiny and weigh nothing really haha.....
Anyway, maybe let me know your thoughts regarding these bearing tangs? Thanks. Not intending to hijack sorry, just thought it related.
Edited by CarsOrBikes on Tuesday 28th November 19:26
Tangs locate the shell in it's correct sideways position. Some engines don't have tangs at all. I'm pretty sure I came a cross a zetec which had shells without tangs. I may be slightly wrong about the details as it was a very long time ago. I recall it seeming a crap idea at the time but crush held the shell in place, not the tangs.
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