So, please share.
Anybody ever broke a Nord by over-revving?
Trying to figure out if anybody actually had a Nord engine fail from over-revving. We all heard of it but the other day I realized I never actually heard about it from someone that had it happen to them... So basically I have only heard "Nords are bad to rev past 6500 because of the long throw" but I never heard about an engine failing. Isn't that strange? If it's that weak one would think it would fail left and right. Right?
So, please share.
So, please share.
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
Yep.
A guy here does rally sprint with a 2.0. Revs to 8000 with stock pistons. Once 3 were at TDC and one BDC. Piston cut clean in half.
Mine revs to 8200 with forged pistons and stock but lightened and polished rods. No failure in since I built it in 96 or so.
I know engines that failed but 90% as they didn't get enough and fresh oil
A guy here does rally sprint with a 2.0. Revs to 8000 with stock pistons. Once 3 were at TDC and one BDC. Piston cut clean in half.
Mine revs to 8200 with forged pistons and stock but lightened and polished rods. No failure in since I built it in 96 or so.
I know engines that failed but 90% as they didn't get enough and fresh oil
Oh, yeah they do break! Couple of guys here I heard of in the last 2-3 years, from dragging the pi$$ out of the things and revving to the sky. One got a ventilated block in the process, just under the starter motor. Micke covers most of it though, if you have good clearances and good oil its difficult to break them.
Right now, everybody's best bet is to buy 4340 rods from the far East. No kidding, them guys have more than 5 hi-perf rod makers. I have seen their products and some friends here use them in 450hp turbo/NOS engines, very serious stuff. I used to squint when I first heard but it turned out they're every bit as good as the 'big' name guys. In a few weeks I should have tensile test results to back up my... blasphemy. I'll only give you guys a hint: Titanium race rods cost $37 (US) each and minimum order quantity is around 20 rods! This s the 'dock' price the maker sells at, then they have distributors who sell 4340 steel 6cylinder sets for 700/750Euros (trade/retail). You can now understand all the fury and slander from the established rod makers! However, not one of them has dared put the rods through a comparison test, if they believe they are so inferior-to prove what? That tensile strength is the same? How would they explain their price then? They just say 'ours are better'-not a very convincing argument. They also claim 'their' 4340 alloy is better than Chinese 4340 alloy because it has fewer or no inclusions...PUT THE RODS TO THE TEST, talk is cheap. I don't like what's happening to the industry any more than the next guy, but its a fact that most carmakers make key engine parts in those plants: Mercedes cranks, Audi/Seat cams etc. If I can save myself $900 on a set of V6 rods, then by all means I'll do it! Stay posted for more (pics and specs) in the coming weeks!
Jim K.
Right now, everybody's best bet is to buy 4340 rods from the far East. No kidding, them guys have more than 5 hi-perf rod makers. I have seen their products and some friends here use them in 450hp turbo/NOS engines, very serious stuff. I used to squint when I first heard but it turned out they're every bit as good as the 'big' name guys. In a few weeks I should have tensile test results to back up my... blasphemy. I'll only give you guys a hint: Titanium race rods cost $37 (US) each and minimum order quantity is around 20 rods! This s the 'dock' price the maker sells at, then they have distributors who sell 4340 steel 6cylinder sets for 700/750Euros (trade/retail). You can now understand all the fury and slander from the established rod makers! However, not one of them has dared put the rods through a comparison test, if they believe they are so inferior-to prove what? That tensile strength is the same? How would they explain their price then? They just say 'ours are better'-not a very convincing argument. They also claim 'their' 4340 alloy is better than Chinese 4340 alloy because it has fewer or no inclusions...PUT THE RODS TO THE TEST, talk is cheap. I don't like what's happening to the industry any more than the next guy, but its a fact that most carmakers make key engine parts in those plants: Mercedes cranks, Audi/Seat cams etc. If I can save myself $900 on a set of V6 rods, then by all means I'll do it! Stay posted for more (pics and specs) in the coming weeks!
Jim K.
Last edited by Jim K on Sun Feb 18, 2007 9:58 am, edited 1 time in total.
Anybody ever broke a Nord by over-revving?
Although the Alfa Nord engine is very sturdy in construction its limitations are the rods. Although they look robust they will fail from fatigue when taken often to high revs. I hear a lot of people saying I rev my engine to 8,000 RPM all the time no problems! But how accurate is the tachometer 
I had spoken to Joe Beninca regarding the use of ARP bolts. He said the stock bolts are fine, the rods fail on the lower part of the beam just above the big end. Stock rods that are ground, polished, shod peened are good for 7,500 RPM.
I have noticed that if you look at a set of used Alfa Nord rod bolts you will see wear marks on the bolt at the part line of the cap, Probably from the bigend bore flexing to oval as the engine revs up. This flexing of the bolts and bigend bore is common in all types of engines but leads to failure from fatigue. Those people reving the engine to 8,000 RPM on stock rods are having their engines living on borrowed time!
From many of the used rods I have I could not make a good set to prepare for performance. Some I noticed were bent in the beam and some had excessive wear on the side flanges of the big end.
After spending a lot of time building a performance engine its worth spending that little more to on purchasing a set of "H" rods as insurance.
After all preparing standard rods will cost and is not inexpensive.
I also purchased a set of rods from the far east and question how good is the material They look good, they are machined accurately and measure up OK. But if I had purchased Carillo's I would feel more comfortable.
I had spoken to Joe Beninca regarding the use of ARP bolts. He said the stock bolts are fine, the rods fail on the lower part of the beam just above the big end. Stock rods that are ground, polished, shod peened are good for 7,500 RPM.
I have noticed that if you look at a set of used Alfa Nord rod bolts you will see wear marks on the bolt at the part line of the cap, Probably from the bigend bore flexing to oval as the engine revs up. This flexing of the bolts and bigend bore is common in all types of engines but leads to failure from fatigue. Those people reving the engine to 8,000 RPM on stock rods are having their engines living on borrowed time!
From many of the used rods I have I could not make a good set to prepare for performance. Some I noticed were bent in the beam and some had excessive wear on the side flanges of the big end.
After spending a lot of time building a performance engine its worth spending that little more to on purchasing a set of "H" rods as insurance.
After all preparing standard rods will cost and is not inexpensive.
I also purchased a set of rods from the far east and question how good is the material
They look good, they are machined accurately and measure up OK. But if I had purchased Carillo's I would feel more comfortable.
As I said before,lots of HIGH hp engines here using Chinese Carrilos..or is that Carillos!!JimGreek wrote:Oh, yeah they do break! Couple of guys here I heard of in the last 2-3 years, from dragging the pi$$ out of the things and revving to the sky. One got a ventilated block in the process, just under the starter motor. Micke covers most of it though, if you have good clearances and good oil its difficult to break them.
Right now, everybody's best bet is to buy 4340 rods from the far East. No kidding, them guys have more than 5 hi-perf rod makers. I have seen their products and some friends here use them in 450hp turbo/NOS engines, very serious stuff. I used to squint when I first heard but it turned out they're every bit as good as the 'big' name guys. In a few weeks I should have tensile test results to back up my... blasphemy. I'll only give you guys a hint: Titanium race rods cost $37 (US) each and minimum order quantity is around 20 rods! This s the 'dock' price the maker sells at, then they have distributors who sell 4340 steel 6cylinder sets for 700/750Euros (trade/retail). You can now understand all the fury and slander from the established rod makers! However, not one of them has dared put the rods through a comparison test, if they believe they are so inferior-to prove what? That tensile strength is the same? How would they explain their price then? They just say 'ours are better'-not a very convincing argument. They also claim 'their' 4340 alloy is better than Chinese 4340 alloy because it has fewer or no inclusions...PUT THE RODS TO THE TEST, talk is cheap. I don't like what's happening to the industry any more than the next guy, but its a fact that most carmakers make key engine parts in those plants: Mercedes cranks, Audi/Seat cams etc. If I can save myself $900 on a set of V6 rods, then by all means I'll do it! Stay posted for more (pics and specs) in the coming weeks!
Jim K.
Mats,Stock polished and peened rods in my turbo~8000rpm with a very eerily silent engine at those revs..never a dyas problems....But I was using ARP rod bolts from the Chrysler as you know...
French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
It seems you all just have a formula with two parameters. Revs and rods.
Remember the rods actually have to pull something. Which means the other important factor is the weight of the piston and the upper part of the rod itself.
Stock Nord pistons weigh 580 g and rods 680 g. The TS pistons are about the same but rods are heavier (stronger?).
People often talk about weight of the pistons but if they don't need the rpm the benefit is not really there. With 10% lighter pistons it should be safe to rev about 5% higher.
Remember the rods actually have to pull something. Which means the other important factor is the weight of the piston and the upper part of the rod itself.
Stock Nord pistons weigh 580 g and rods 680 g. The TS pistons are about the same but rods are heavier (stronger?).
People often talk about weight of the pistons but if they don't need the rpm the benefit is not really there. With 10% lighter pistons it should be safe to rev about 5% higher.
mats,
my 2.0 race motor has standard rods that have been polished. i am running paul spruell JE pistons.
the motor was built 3 years ago and has seen a lot of hard racing. it hasn't missed a beat. i rev it to 7600rpm all day long, i use a good electronic tach that im pretty confident about its accuracy.
the other guys i race have had similar success. a couple of guys pull up to 8500rpm.
i have known one guy who used to pull around 9krpm but had issues with the block flexing.
from paddock talk it seems to me that the general consensus is that up to 8500rpm is about the max you'd really want to be pulling. in saying that though. most try to keep the revs to around 8k rpm.
interesting topic. it'll be interesting to see who comes forward with failure stories.
i only know of one guy who has thrown a rod! i cant remember the circumstances though.
hope this helps.
regards
ben
my 2.0 race motor has standard rods that have been polished. i am running paul spruell JE pistons.
the motor was built 3 years ago and has seen a lot of hard racing. it hasn't missed a beat. i rev it to 7600rpm all day long, i use a good electronic tach that im pretty confident about its accuracy.
the other guys i race have had similar success. a couple of guys pull up to 8500rpm.
i have known one guy who used to pull around 9krpm but had issues with the block flexing.
from paddock talk it seems to me that the general consensus is that up to 8500rpm is about the max you'd really want to be pulling. in saying that though. most try to keep the revs to around 8k rpm.
interesting topic. it'll be interesting to see who comes forward with failure stories.
i only know of one guy who has thrown a rod! i cant remember the circumstances though.
hope this helps.
regards
ben
1962 Giulia Ti Race-car
1969 Giulia Super
1987 GTV6- new race project.
1969 Giulia Super
1987 GTV6- new race project.
Another issue is that revving just for the fun of it doesn't make much sense.
Again you may correct me if you disagree but getting max power of the Nord engine past 7500 is something not many have achieved.
Not talking what is possible but what should be a rpm to use:
To be efficient you MUST be able to pull some hundred rpm past max hp rpm. To get a real number let's say 500. Having 1k to stretch in some places is not wrong.
Then again revving 8000 when max power is at 6500 only slows you down.
And the saddest of all; I've seen (even on this forum I recall) cases where a nicely rising power curve is cut by the rpm limiter. As sad as it is dumb.
Again you may correct me if you disagree but getting max power of the Nord engine past 7500 is something not many have achieved.
Not talking what is possible but what should be a rpm to use:
To be efficient you MUST be able to pull some hundred rpm past max hp rpm. To get a real number let's say 500. Having 1k to stretch in some places is not wrong.
Then again revving 8000 when max power is at 6500 only slows you down.
And the saddest of all; I've seen (even on this forum I recall) cases where a nicely rising power curve is cut by the rpm limiter. As sad as it is dumb.
Another piece of trivia re. rods breaking: almost always, 4-stroke engine rods break during shifting gears at very high revs, when the throttle is closed...there's no "cushion" over the piston at those instants and the pulling force the ascending piston exerts is much higher (a condition that never happens in 2-stroke engines where all cycles are 'hot'). That's exactly where a lighter piston is of benefit, having less inertia.
Jim K.
Jim K.