ZRP Forged Conrods

[e21Mark]

I'm rebuilding the s14 engine in my BMW E30 M3 and have been looking at replacing the OE conrods. In fact, I have also been considering shot peening and balancing the OE rods as well. Ideally I would opt for Arrow rods, as they're tried and tested, but at £1 100 they're an added expense I simply cannot afford. Rebuilding an s14 isn't cheap and I have already spent several £k on new Schrick cams, head work, lighter flywheel & an upgrade to standalone ignition.

Anyway, after ignoring the various Chinese options I found these from ZRP and wondered if anyone else had used them? http://zrp-rods.co.uk/bmw-m3-s14-b23-s14-b25-conne...

Obviously I would use best quality bearings and ARP bolts but am still undecided between the ZRP and overhauling the OE rods?

It's important I get this build right first time but I am at my limit when it comes to budget.

[e21Mark]

stevieturbo said:

e21Mark said:

I'm rebuilding the s14 engine in my BMW E30 M3 and have been looking at replacing the OE conrods. In fact, I have also been considering shot peening and balancing the OE rods as well. Ideally I would opt for Arrow rods, as they're tried and tested, but at £1 100 they're an added expense I simply cannot afford. Rebuilding an s14 isn't cheap and I have already spent several £k on new Schrick cams, head work, lighter flywheel & an upgrade to standalone ignition.

Anyway, after ignoring the various Chinese options I found these from ZRP and wondered if anyone else had used them? http://zrp-rods.co.uk/bmw-m3-s14-b23-s14-b25-conne...

Obviously I would use best quality bearings and ARP bolts but am still undecided between the ZRP and overhauling the OE rods?

It's important I get this build right first time but I am at my limit when it comes to budget.

I'd never heard of them until a couple of years ago at Autosport. Then I have noticed a few places using them who post on social media etc and havent noticed any bad reports. If you google....they do sort of suggest they are based in Greece, although other googles suggest they're basically Chinese. But then what isnt made in China these days.
As long as the right quality controls are in place nothing wrong with it.

Any of the places selling cheaper stuff, will ultimately nearly always be Chinese anyway regardless of name. Even cheap no brand stuff seems to hold up well though, but as you say, defo use proper ARP bolts although ZRP seem to supply these anyway

Just had a long chat to the guys at TSR who supply and use them in their VAG turbo builds. I was pretty candid about my concerns re quality and they said they used them in all their builds and had regularly seen 500+bhp with no issues. Anyway, they're shipping a set out to me so we shall soon see I guess?

[e21Mark]

Luther Blissett said:

I think Robson's in Coventry would be worth a call.

Unfortunately they don't do BMW.

[e21Mark]

227bhp said:

They were hardly going to say no, they're a bit iffy.

No, but I was able to ask about specific builds/applications and research TSR and their cars in an effort to allay some initial fears regarding fit and quality. I also confirmed with ARP that they do supply their bolts.

My main reason for replacing the rods is their being over 26 years old and that they've done over 100k miles. I'm fitting CP pistons, ARP studs/bolts, Schrick etc and am already a good few £k in. Yes, I would have preferred Arrow rods but TSR did me an excellent deal and the money saved will cover mapping. I have limited funds and am trying to get the best bang for my buck, whilst maintaining reliability.

My engine builder will be checking the new rods and will let e know if he has any reason to suspect their fit and quality. These rods are commonly used in Greece and there are several VAG and Mini tuners using them without issue.

Edited by e21Mark on Saturday 24th December 20:28

[e21Mark]

I did call.

Anyway, rods arrived and all appears OK. Time will tell I guess?




Happy Christmas.

Edited by e21Mark on Sunday 25th December 06:42

[e21Mark]

Interesting to hear.

Am going to take time to have these rods properly inspected to see if there is any difference in each rod, confirm they're straight etc before (assuming all is well) using them. As mentioned earlier, the supplier also actually use these rods in their VAG engine builds and haven't experienced any failures due to quality control.

Are there any specific measurements & checks you can suggest?

[e21Mark]

Thanks guys. Appreciated. I'll let you know what I find from checks.

[e21Mark]

Thanks Mignon! I'll post results relating to the ZRP.

[e21Mark]

Apologies - missed replies.

Engine builder checked rods and although not overly impressed he did say they were within tolerance. He also said they were pretty heavy. Anyway, am just waiting to get the newly built engine back now.

[e21Mark]

Are forged rods always going to be heavier?

Also, how is the added weight likely to impact on running/performance? (If at all)

[e21Mark]

Have to say my engine went together without issue and is performing well. I'm very happy.

[e21Mark]

If honest, I didn't notice any marks and my builder didn't mention anything apart from their weight. They went together with the new pistons etc no problem and I'm about 1200 miles in now.

[e30m3Mark]

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.

[e30m3Mark]

227bhp said:

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.

Why not? Can you specifically attribute the failure to a conrod?

In part, yes. You'll have to excuse my lack of engineering knowledge / poor memory but, for the most part, it was to do with the lack of an oil way at the little end and the small lack of surface material? Basically poor rod design, compounded by the cooling issue etc I'd suffered.

[e30m3Mark]

227bhp said:

They must have some oiling hole in the rod? It's usually a drilling for splash feed, not the rifle drilling you mean.
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.

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.

[e30m3Mark]

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.

[e30m3Mark]

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.

[e30m3Mark]

stevesingo said:

Maybe Mark has his stock rods to hand to check those.

I'll take a look later.

[e30m3Mark]

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?

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.

[e30m3Mark]

Thanks for that Peter.