Compression Ratio advise please on forge build

Skalabala

Member +
the scat rods for the 4e I've been using for a quite a while without any issues.

Had lots of issues with PEC stuff.
DSCN4333_zps54c7740d.jpg

Tim wasn't this a clearance problem? Any rod will give a problem if clearances/oil feed is not up to standard :p Interesting guaging pin :D
I wish the 4E combustion chamber was like Honda. I also want a 11:1 CR and boost the crap out of it :D
 
Tim wasn't this a clearance problem? Any rod will give a problem if clearances/oil feed is not up to standard :p Interesting guaging pin :D
I wish the 4E combustion chamber was like Honda. I also want a 11:1 CR and boost the crap out of it :D

no this was the worst one of 4 after a major failure. All 4 conrods had very slight bends in them only running slightly above stock power. Because of the bends it caused the bearing to overload on 1 side leading to bearing failure. This one was the first one to majorly fail where the bearing grabbed, spun then welding itself to the crank causing that huge bend and then pushing itself out the side of the engine block casing.

all 4 bearings were in a state of failure, but this one was the first to grab and then the resulting damage was caused from that event. so that bend wasn't caused from normal operation. but the initial bends in all 4 rods were down to just poor construction which lead to this
 

Skalabala

Member +
no this was the worst one of 4 after a major failure. All 4 conrods had very slight bends in them only running slightly above stock power. Because of the bends it caused the bearing to overload on 1 side leading to bearing failure. This one was the first one to majorly fail where the bearing grabbed, spun then welding itself to the crank causing that huge bend and then pushing itself out the side of the engine block casing.

all 4 bearings were in a state of failure, but this one was the first to grab and then the resulting damage was caused from that event. so that bend wasn't caused from normal operation. but the initial bends in all 4 rods were down to just poor construction which lead to this

Holy molly! No pec for me thanks :D
 

_GAZ_EP85_

Member +
ab's you need to talk to builder, see how much he has taken off the head and what work he has done to the combustion chamber
 

sx_turbo

Lifer
Is this with stock components or would the rods etc need replacing too?

rods would be fine, the stock rods are actually quite strong, just dont go above stock rev limits, and have some mechanical sympathy when driving, i.e dont engine brake, or bounce off the rev limiter
 

abbott

Member +
Regards to the bent rod issue PEC would like to comment but they are having issues joining the forum but this is what they sent me to reply to the thread

"This is an open letter to all members of the Starlet club and anyone else who should read this. This thread was brought too my attention some time ago but I have not had the time to sit down and draft a response to some of the questions raised in this thread until now, apologies for the delay.

The rod that has been picturered earlier in this thread, as far as I know, is one of ours. What has been missed out though is that this is the first time I've seen this or have even been made aware of its existence. I have not knowingly dealt direct with any company called TB Performance and have not been contact by them relating too this matter so I can only assume that they have dealt with one of our re-sellers but then I have not heard anything from any of them either.

I have to query why the owner decided to post on forum's rather then contact the manufacturer or even the company who sold him the rods?

To clarify this statement:

Because of the bends it caused the bearing to overload on 1 side leading to bearing failure. This one was the first one to majorly fail where the bearing grabbed, spun then welding itself to the crank causing that huge bend and then pushing itself out the side of the engine block casing.

This is quite incorrect. Rods will not bend on their own, there has to be an external force. In this instance, it looks like an oil pressure or supply problem has caused the bearing to super heat due to lack of oil, then grip and spin on the rod / journal. If it gets hot enough, this will "weld" the bearing rod and journal together and cause the whole rotating assembly to grind to a hale mid cycle. This will bend the rod as it cannot take the forces being loaded on to it.

2usim3a.jpg

(if the link doesnt work James please let me know and I will send you the pic to post up).

This is a Peugeot rod that we were running in an engine in house with a new type of oil pump. The pump was running out of pressure at higher rpm's and was causing similar problems to those I mentioned above. Note the same decolourisation around the big end as the rod posted earlier, these are the tell tale signs oil supply problems.

We have often maintained that it does not matter who you buy from or how much you spend, if you have fundamental problems with your engine such as oil supply and detonation, it makes no difference wether you have spent £50 or £5000 the internal components will eventually fail.

To clear up some of the specific questions on here...

1. No, our rods are not made for us by Cosworth, nor do we make rods for Cosworth. We used to deal with Cosworth for pistons but that is another story.

2. Block notching. Older versions of our con rods used to need the blocks notching due to space constrictions inside the crank case. When designing rods, it is essential to leave enough material in places to maintain strength in key areas and also use the right radiuses to also maintain strength. Over time, we find ways to modify the rod drawings to improve strength and fitment, an evolution of the design if you will. Our present rod design is the optimal design we have at present but older versions are still more then up to the jobs they were supplied for and current customers should not worry.

Lastly, on a more personal note. Dave at TM was a close friend of the staff here and his loss is still felt. One of the reasons why Dave and ourselves became so close was his regular visits to us, helping us work on the design of Starlet components and us in return supporting him in his business and also explaining too him the technical constraints in mass manufacturing parts such as this.

We still love Starlet engines here and will continue to develop new components for them (watch out for some new pistons at the Autosport show) and if any one wants to know anything at all about anything and wants to show us anything that has happened to another person that we are unaware of (as has happened here), please contact me directly, we are always happy to try and help.

Dave - MD PEC

P.E.C. ltd www.performanceenginecomponents.com
Europe's finest selection of Performance Engine Components
01376 583030 9-5 Mon-Fri
Due to large volumes of e-mails received, please include all previous e-mail messages when responding. This allows us to view the complete situation and will result in a quicker response. Thank you.
 
The picture I posted wasn't from an engine I've built. It was in an engine I was asked to fix. The engine failure happened with the pec rods pictured. I personally
Just to reply to the subject.

I've never dealt with Pec or any of there re-sellers this is why my business name is unfamiliar.

I didn't say this was for a 4E engine.

I totally agree with what your saying about what's happened to the rod and from the picture i can understand why you've said its overheated from the metal discolouration and the welded bearing is what's caused the rod to fail in such a spectacular fashion. This is basically the truth, but the bearing failed in my opinion because of the conrod which then lead onto the other issues, My conclusion regarding why the bearing failed was down to the condition of the other rods in the same engine. All showed some small degree of twist/bend which was loading the bearing surfaces on the one edge. Oil pressure and pump was inspected and found to be in good condition and putting out a good pressure. Weather or not it encountered surge from cornering I can't say 100% but seeing this was from a road going application is does seem very unlikely, but I'll give the benefit of the doubt and say it was "possible". But doesn't explain the rod straightness issue on the majority of the cylinders where no other failures were present just a irregular bearing surface wear. On the cylinders where it was just irregular wear on the bearings and the other faces were still in perfect condition I checked the crank journal and the rod big-end and all were within specs so the irregular wear wasn't down to poor machining from the previous builder. The bearings with the most wear (apart from the one that failed) the rod has a slight "lean" to it towards the side with most bearing wear. Weather or not this was down to bending in operation or just down to a warpage in the forging process that slipped through quality control I can't say.

This wasn't a smear campaign just reporting what I have found personally. I've fitted Pec rods in the past that were supplied by the customer without issue, but there are other brands I prefer to use at the moment if I'm supply and building the engine 100% myself for a customers needs, but I'm always open minded on what I offer to customers.

Lets just put this down to an isolated incident and see if anything comes up in the future.

But just for the record, and I whole hearteningly apologise if I've got this wrong, but are you saying your Conrods are made in-house by you in the UK or are they actually imported from a Chinese manufacturer and re-branded as your own, as I've been informed is the case? If this is the case then I can understand and more believe that the rods were out of alignment from the forging process and just missed the quality control in china, as I doubt you re-quality control check everything that comes through your factory. I can believe this because we've had mis-machined parts from some of the largest USA manufactures in the world that have got a QC stamp on them and were still wrong.

Tim
TB Developments
 
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