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Discussion Starter · #1 ·
Hi lads

We all know how much of a lottery stock rods seem to be, with some folk apparently able to run significantly more than others and unlucky folk throwing a rod on near stock power.

But I was wondering how many folk that have had the ARP conrod bolts fitted to stock rods have had a rod break and at what power and torque level where you at?

Cheers:thumbup:
 

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Id be curious to hear results too but from my own experience it was 100 percent the rod that let go, it snapped very clearly and upon investigation the rod bearing was as good as the rest ie mint, and bore was fine no sign of excessive bore wear to say that piston had expanded causing it to sieze in bore and cause rod to snap. Mine snapped very shortly after a remap on the way home. No rod bolt would have made a difference in my case it was purely a case of too much torque for the rods some get lucky maybe its down to the mapping im not sure but like we all know its a lottery.

Edit mine was at 1.55bar peak and stock rod bolts unopened engine.
 

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Discussion Starter · #4 · (Edited)
Id be curious to hear results too but from my own experience it was 100 percent the rod that let go, it snapped very clearly and upon investigation the rod bearing was as good as the rest ie mint, and bore was fine no sign of excessive bore wear to say that piston had expanded causing it to sieze in bore and cause rod to snap. Mine snapped very shortly after a remap on the way home. No rod bolt would have made a difference in my case it was purely a case of too much torque for the rods some get lucky maybe its down to the mapping im not sure but like we all know its a lottery.

Edit mine was at 1.55bar peak and stock rod bolts unopened engine.
Cheers for your input, that's interesting to know, what torque figure was it kicking out before it let go? Do you have a dyno graph at all.

Could be interesting to see the dyno graphs of cars that have had a rod go afterwards, there may be some similarities on the torque curves perchance?

The reason I ask is I wander if they just need to be tuned in a different manner...

I used to love Fiat Coupe 20v turbo's and the general consensus was that they wouldn't do over 380hp or so or the rods went, but lots of Swedish enthusiasts were reported to be running figures as high as 500hp on stock rods, they had focussed the tuning on high end rpm power rather than improving torque and mapped them to keep the torque down but still develop more hp by using larger turbos than they should have. I guess the trade off is that all the power is at the top but I quite like that.

Looking through the articles on here there was Rich W's Evo 6 kicking out 420ish hp and he had gone for a larger turbo and interestingly ARP bolts...on stock rods, and Power Engineering's car had ARP's fitted..
 
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Id be curious to hear results too but from my own experience it was 100 percent the rod that let go, it snapped very clearly and upon investigation the rod bearing was as good as the rest ie mint, and bore was fine no sign of excessive bore wear to say that piston had expanded causing it to sieze in bore and cause rod to snap. Mine snapped very shortly after a remap on the way home. No rod bolt would have made a difference in my case it was purely a case of too much torque for the rods some get lucky maybe its down to the mapping im not sure but like we all know its a lottery.

Edit mine was at 1.55bar peak and stock rod bolts unopened engine.
Did you feel aggrieved with the mapper or did you take a balanced view on it?
 

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Discussion Starter · #6 · (Edited)
People need to get off this "what will my rods take" train of thought because most of the rods you are talking about are 15 to 20 years old now.
If you are concerned about the rods then replace them, metal fatigue will always win.
Hi Mat, you may well be right i'm just from the old school a tad and when I was younger was pretty obsessed with the old A series mini engine tuning game and many a rod had been checked and polished and stress releived that were older than 20 years and survived many a high rpm race meeting in mini race cars so I'm not too sure about the fatigue thing entirely, obviously it can happen and there is a possibility but its the extent of such that i wonder is possible..

Not shutting you down at all, just an interesting topic thats all:smthumbup

And just to add, I cant understand why some uprated rods have not been developed that negate the whole circlip malarky and fit stock pistons and gudgeons, obviously extreme care would be needed when removing the pin and fitting a new rod not to damage the piston or misshape it, but seems a hole in the market for it..
 
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Hi Mat, you may well be right i'm just from the old school a tad and when I was younger was pretty obsessed with the old A series mini engine tuning game and many a rod had been checked and polished and stress releived that were older than 20 years and survived many a high rpm race meeting in mini race cars so I'm not too sure about the fatigue thing entirely, obviously it can happen and there is a possibility but its the extent of such that i wonder is possible..

Not shutting you down at all, just an interesting topic thats all:smthumbup
Turbo charged petrol cars endure much more stress over time than an NA engine.
I'm giving you my own experience from over 20 years working with the 4G63 engine, the rods fatigue, it's a fact that you must take into account when tuning them.
 

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Pretty sure any rod failure will be boost related on Evos, a force acting down upon the conrods, where as a bottom end bolt failure is usually associated with high rpm cars?
 

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Personally I wouldn't even consider using my stock rods or OE ECU if doing engine mods. This is the problem these cars are getting old and who knows how they've been used over the years. Mines done 10k and I'd still be paranoid about the rods if I had a remap.

I have the thinking of "prevention before cure" with these, parts are getting scarce.
 

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Cheers for your input, that's interesting to know, what torque figure was it kicking out before it let go? Do you have a dyno graph at all.

Could be interesting to see the dyno graphs of cars that have had a rod go afterwards, there may be some similarities on the torque curves perchance?

The reason I ask is I wander if they just need to be tuned in a different manner...

I used to love Fiat Coupe 20v turbo's and the general consensus was that they wouldn't do over 380hp or so or the rods went, but lots of Swedish enthusiasts were reported to be running figures as high as 500hp on stock rods, they had focussed the tuning on high end rpm power rather than improving torque and mapped them to keep the torque down but still develop more hp by using larger turbos than they should have. I guess the trade off is that all the power is at the top but I quite like that.

Looking through the articles on here there was Rich W's Evo 6 kicking out 420ish hp and he had gone for a larger turbo and interestingly ARP bolts...on stock rods, and Power Engineering's car had ARP's fitted..
I've got a Coupe 20v turbo. It's only stock at the minute but what a surprising car it was when I first jumped in! I do fancy turning it up a bit too! I can imagine the thing to be mental with 400bhp never mind 500.
 

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Discussion Starter · #11 ·
I've got a Coupe 20v turbo. It's only stock at the minute but what a surprising car it was when I first jumped in! I do fancy turning it up a bit too! I can imagine the thing to be mental with 400bhp never mind 500.
They're great cars, I've had a couple one at 350hp with a 62 trim turbo and other bits and a remapped stock one, both great fun, get a custom exhaust made in 3" from turbo back and it not only releases an Audi-esque 5 cylinder warble but really improves the pick up.
 

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They're great cars, I've had a couple one at 350hp with a 62 trim turbo and other bits and a remapped stock one, both great fun, get a custom exhaust made in 3" from turbo back and it not only releases an Audi-esque 5 cylinder warble but really improves the pick up.
I'll look into that, any recommendations as to where I might get one made? It's not running right at the mo, it's got an injector dash light and runs a cylinder down. I just need to make time to sort it out, I've missed using it.
 

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Cheers for your input, that's interesting to know, what torque figure was it kicking out before it let go? Do you have a dyno graph at all.

Could be interesting to see the dyno graphs of cars that have had a rod go afterwards, there may be some similarities on the torque curves perchance?

The reason I ask is I wander if they just need to be tuned in a different manner...

I used to love Fiat Coupe 20v turbo's and the general consensus was that they wouldn't do over 380hp or so or the rods went, but lots of Swedish enthusiasts were reported to be running figures as high as 500hp on stock rods, they had focussed the tuning on high end rpm power rather than improving torque and mapped them to keep the torque down but still develop more hp by using larger turbos than they should have. I guess the trade off is that all the power is at the top but I quite like that.

Looking through the articles on here there was Rich W's Evo 6 kicking out 420ish hp and he had gone for a larger turbo and interestingly ARP bolts...on stock rods, and Power Engineering's car had ARP's fitted..
No dyno buddy it was road mapped as a guess 350/350 just basic bolt on mods filter and downpipe and exhaust.
 

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Did you feel aggrieved with the mapper or did you take a balanced view on it?
If im honest i did but i knew it was a risk and many have let go at stock power so i took the hit on the chin i told him it blew and we just discussed a new engine i didnt ask for him to refund or pay for any damage and he didnt offer to either.

Later on we did load up the map and checked timimg vs other cars we knew have been running on stock engines for years and mine had alot more timing compared to the other maps so torque did come in quite aggressively this maybe caused too much stress to rods.
 

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If im honest i did but i knew it was a risk and many have let go at stock power so i took the hit on the chin i told him it blew and we just discussed a new engine i didnt ask for him to refund or pay for any damage and he didnt offer to either.

Later on we did load up the map and checked timimg vs other cars we knew have been running on stock engines for years and mine had alot more timing compared to the other maps so torque did come in quite aggressively this maybe caused too much stress to rods.
What did it make on the dyno?
 

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A boost spike would probably cause a sharp rise in torque lower down
 
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