Engine Limits vs Power -- Sharing Some Knowledge
Registered User
Joined: Nov 2009
Posts: 1,021
From: Italy
Rep Power: 86
US cars may not see the autobahn, but a lot of them are tracked....many guys here like drag strips too....IMO the probability of bending rods should not be so much different after all....
Rather than sustained high speed driving, this sounds more "dangerous" to me:
Of course back to back accelerations on longer gears can be hard on the engine too..
Rather than sustained high speed driving, this sounds more "dangerous" to me:
I'm just thinking out loud now, but we bent our rods while doing a warm up just prior to a dyno run. We had just installed a Tilton three disc clutch and had drag radials on all four wheels. We were doing a pretty heavy launch and it was after the launch we noticed the "ticking." The rpm's started at about 6000 but they were pulled down on the launch.
Last edited by emadelta86; May 2, 2011 at 09:22 AM.
Registered User
Joined: Oct 2003
Posts: 427
From: England
Rep Power: 59
Whilst some of the big power cars have done an occasional 1/4, it's pretty rare and also only means full-throttle for 9-11 seconds. Also very few high power cars ie 700-1000bhp+ get tracked, in fact I'd love to hear of instances where they have been.
Registered User
Joined: Nov 2009
Posts: 1,021
From: Italy
Rep Power: 86
One thing is sure, if the rod limit is XXX Nm, no matter how you use that torque, you are going to bend it...the simple fact that cars out there can do even one single pull without bending rods is enough to me to conclude that we still don't know which is the real limit.
I could be totally wrong though. I only know one thing for sure, when deformation is involved, loading a component over its limit once is sufficient to begin deforming it.
We are not talking fatigue stress and failure here. Of course rods that withstand higher than stock torque levels will have less stress cycles available before they fail (break). But they are bending here, after a relatively little amount af cycles.
I could be totally wrong though. I only know one thing for sure, when deformation is involved, loading a component over its limit once is sufficient to begin deforming it.
We are not talking fatigue stress and failure here. Of course rods that withstand higher than stock torque levels will have less stress cycles available before they fail (break). But they are bending here, after a relatively little amount af cycles.
Banned
Joined: Apr 2011
Posts: 27
From: France
Rep Power: 0
Big respect for Champion for posting this.
The simple fact is that torque bends rods, it something the Euro tuners found out a long long time ago on the 996TT. Thats why Ruf/RS Tuning and others won't go above about 800nM without building the internals. This has also been derided on US Porsche forums for as long as I can remember!
The reason many US cars will stay together with stock internals at higher power levels is simply that they just don't get the sustained loading that the German cars do. In my old Ruf GT2 I've been on a drive in Germany of 120 miles that averaged over 145mph and included exceeding 200mph several times, I've also done 0-300kph+ (on GPS) 30 times in the same day, even once including 5 back-to-back runs of 0-200mph.
Alois Ruf told me that they fitted upgraded rods to the Nardo package for the 996TT, which makes only around 600hp and similar torque after they bent the stock rods with sustained high-load high-speed driving. This was way back in 2001/2002 I recall.
The simple fact is that torque bends rods, it something the Euro tuners found out a long long time ago on the 996TT. Thats why Ruf/RS Tuning and others won't go above about 800nM without building the internals. This has also been derided on US Porsche forums for as long as I can remember!
The reason many US cars will stay together with stock internals at higher power levels is simply that they just don't get the sustained loading that the German cars do. In my old Ruf GT2 I've been on a drive in Germany of 120 miles that averaged over 145mph and included exceeding 200mph several times, I've also done 0-300kph+ (on GPS) 30 times in the same day, even once including 5 back-to-back runs of 0-200mph.
Alois Ruf told me that they fitted upgraded rods to the Nardo package for the 996TT, which makes only around 600hp and similar torque after they bent the stock rods with sustained high-load high-speed driving. This was way back in 2001/2002 I recall.
It is simple!!! Euro tuners can't tune those cars
Many many +800bhp ( not whp ) built cars by Euro tuners got Kaboom.
Have u heard about two lightweight Sportec cars ( 850hp and SPR1 ) got blown while testing them on Abu Dhabi 1/4 mile dragstrip infront of Sportec crew.
I guess no need to talk about 9ff regarding reliability lol
Euro tuners can't even built reliable motors..How do expect them to build simple fast bolt-ons cars???
Again take ur time watching U.S tuned cars in Russia and middeleast.
Last edited by Boostholic; May 2, 2011 at 02:28 PM.
With all respect but u need to look U.S tuned cars vids all over youtube in Russia and middeleast...They r hitting +300kmh weekly on 750hp kit not 600hp.
It is simple!!! Euro tuners can't tune those cars
Many many +800bhp ( not whp ) built cars by Euro tuners got Kaboom.
Have u heard about two lightweight Sportec cars ( 850hp and SPR1 ) got blown while testing them on Abu Dhabi 1/4 mile dragstrip infront of Sportec crew.
I guess no need to talk about 9ff regarding reliability lol
Euro tuners can't even built reliable motors..How do expect them to build simple fast bolt-ons cars???
Again take ur time watching U.S tuned cars in Russia and middeleast.
It is simple!!! Euro tuners can't tune those cars
Many many +800bhp ( not whp ) built cars by Euro tuners got Kaboom.
Have u heard about two lightweight Sportec cars ( 850hp and SPR1 ) got blown while testing them on Abu Dhabi 1/4 mile dragstrip infront of Sportec crew.
I guess no need to talk about 9ff regarding reliability lol
Euro tuners can't even built reliable motors..How do expect them to build simple fast bolt-ons cars???
Again take ur time watching U.S tuned cars in Russia and middeleast.
and what u mentioned based on what ?
i've personally experienced working with evoms protomotive softronic as american tuners and worked with FVD and ruf as european tuners all above mentioned were excellent
whats ur experience and what are u basing your reliability methods on ?
Banned
Joined: Apr 2011
Posts: 27
From: France
Rep Power: 0
pls dont turn this discussion to euro tuners vs american tuners
and what u mentioned based on what ?
i've personally experienced working with evoms protomotive softronic as american tuners and worked with FVD and ruf as european tuners all above mentioned were excellent
whats ur experience and what are u basing your reliability methods on ?
and what u mentioned based on what ?
i've personally experienced working with evoms protomotive softronic as american tuners and worked with FVD and ruf as european tuners all above mentioned were excellent
whats ur experience and what are u basing your reliability methods on ?
The guy said " The reason many US cars will stay together with stock internals at higher power levels is simply that they just don't get the sustained loading that the German cars do. In my old Ruf GT2 I've been on a drive in Germany of 120 miles that averaged over 145mph and included exceeding 200mph several times, I've also done 0-300kph+ (on GPS) 30 times in the same day, even once including 5 back-to-back runs of 0-200mph "
The guy start the comparo!!!
Last edited by eclou; May 5, 2011 at 05:28 AM. Reason: rude
Registered User
Joined: Oct 2003
Posts: 427
From: England
Rep Power: 59
My point is not meant to deride in any way the US tuners, who have in my opinion moved on the game massively from what the Euro-tuners did in terms of proven power and speeds etc. There are many very professional US Tuners I have the highest of respect for.
My point remains the same though, those tuners who have run the cars with high-torque and really hard use (that is typically not found in US Street-driving) have found that they can bend the rods. A stock rod that bends with 600lb ft at Ruf or RS Tuning is exactly the same rod that has bent for cjv and now Champion etc.
Mention has been made of the US tuned cars running in Russia. These are mainly Switzer cars and they have been performing extremely well and lasting on stock rods. Guess why, look at their dynos, Switzer tune their cars to make power, but hold back on the torque. The P800 makes about 800hp, but only about 650lb ft torque. I'd bet thats because Switzer also know that running massive boost in the low/mid-range will easily make the torque, but the rods will not cope if it's used hard.
I used to have a few Nissan GTRs (had all of them 32-35). One of the reasons the legendary RB26 held together so well was that it revved so high, you can make 1000bhp with an engine that only makes 650lb ft, if it can rev to near 9000rpm. A Formula 1 engine makes about 800bhp at 18,000 rpm, but it's peak torque is under 225lb ft ! Great article here: http://www.epi-eng.com/piston_engine..._cup_to_f1.htm
My point remains the same though, those tuners who have run the cars with high-torque and really hard use (that is typically not found in US Street-driving) have found that they can bend the rods. A stock rod that bends with 600lb ft at Ruf or RS Tuning is exactly the same rod that has bent for cjv and now Champion etc.
Mention has been made of the US tuned cars running in Russia. These are mainly Switzer cars and they have been performing extremely well and lasting on stock rods. Guess why, look at their dynos, Switzer tune their cars to make power, but hold back on the torque. The P800 makes about 800hp, but only about 650lb ft torque. I'd bet thats because Switzer also know that running massive boost in the low/mid-range will easily make the torque, but the rods will not cope if it's used hard.
I used to have a few Nissan GTRs (had all of them 32-35). One of the reasons the legendary RB26 held together so well was that it revved so high, you can make 1000bhp with an engine that only makes 650lb ft, if it can rev to near 9000rpm. A Formula 1 engine makes about 800bhp at 18,000 rpm, but it's peak torque is under 225lb ft ! Great article here: http://www.epi-eng.com/piston_engine..._cup_to_f1.htm
Last edited by Guy; May 3, 2011 at 06:52 AM.
Registered User
Joined: May 2008
Posts: 1,768
From: Cyprus
Rep Power: 111
So according to you my car is a time bomb
.
I have my car tuned from US tuner putting over 900Nm on the wheels, I drive the car as a weekend toy so I usually abuse it
. I have 34k km/s on it 4 sets of tyres if that makes sense. I street race very often from 30 to 300, some times I do this repeatedly, I also drive to the hills on the limits 2nd 3rd gear all the time, I have also changed my PCCB pads due to hard driving and the car drives like a rocket.
. I have my car tuned from US tuner putting over 900Nm on the wheels, I drive the car as a weekend toy so I usually abuse it
. I have 34k km/s on it 4 sets of tyres if that makes sense. I street race very often from 30 to 300, some times I do this repeatedly, I also drive to the hills on the limits 2nd 3rd gear all the time, I have also changed my PCCB pads due to hard driving and the car drives like a rocket. My point is not meant to deride in any way the US tuners, who have in my opinion moved on the game massively from what the Euro-tuners did in terms of proven power and speeds etc. There are many very professional US Tuners I have the highest of respect for.
My point remains the same though, those tuners who have run the cars with high-torque and really hard use (that is typically not found in US Street-driving) have found that they can bend the rods. A stock rod that bends with 600lb ft at Ruf or RS Tuning is exactly the same rod that has bent for cjv and now Champion etc.
Mention has been made of the US tuned cars running in Russia. These are mainly Switzer cars and they have been performing extremely well and lasting on stock rods. Guess why, look at their dynos, Switzer tune their cars to make power, but hold back on the torque. The P800 makes about 800hp, but only about 650lb ft torque. I'd bet thats because Switzer also know that running massive boost in the low/mid-range will easily make the torque, but the rods will not cope if it's used hard.
I used to have a few Nissan GTRs (had all of them 32-35). One of the reasons the legendary RB26 held together so well was that it revved so high, you can make 1000bhp with an engine that only makes 650lb ft, if it can rev to near 9000rpm. A Formula 1 engine makes about 800bhp at 18,000 rpm, but it's peak torque is under 225lb ft ! Great article here: http://www.epi-eng.com/piston_engine..._cup_to_f1.htm
My point remains the same though, those tuners who have run the cars with high-torque and really hard use (that is typically not found in US Street-driving) have found that they can bend the rods. A stock rod that bends with 600lb ft at Ruf or RS Tuning is exactly the same rod that has bent for cjv and now Champion etc.
Mention has been made of the US tuned cars running in Russia. These are mainly Switzer cars and they have been performing extremely well and lasting on stock rods. Guess why, look at their dynos, Switzer tune their cars to make power, but hold back on the torque. The P800 makes about 800hp, but only about 650lb ft torque. I'd bet thats because Switzer also know that running massive boost in the low/mid-range will easily make the torque, but the rods will not cope if it's used hard.
I used to have a few Nissan GTRs (had all of them 32-35). One of the reasons the legendary RB26 held together so well was that it revved so high, you can make 1000bhp with an engine that only makes 650lb ft, if it can rev to near 9000rpm. A Formula 1 engine makes about 800bhp at 18,000 rpm, but it's peak torque is under 225lb ft ! Great article here: http://www.epi-eng.com/piston_engine..._cup_to_f1.htm
Registered User
Joined: Oct 2003
Posts: 427
From: England
Rep Power: 59
No, the point is one of expected life and probability.
A stock Porsche engine is designed so the rods will never bend and that the engine will never blow-up. That is not to say that there isn't a very very small probability of a failure.
The higher the engine is tuned the greater the chance of a failure at any given point and the shorter the expected life of the engine, which is why race engines get rebuilt regularly.
There is clearly a point above which the chance of failure increases dramatically and in this case it's directly related to the strength of the rods. That said you can only observe/predict an expected life and clearly there is a huge randomness around what happens to any individual engine.
If you run 1000nM instead of factory 680nM, you might for example reduce the expected engine life from 20 years, to 3-5 years. However an individual engine might vary between only a few months and some lasting 10 years.
The point is that beyond a certain torque level you introduce a risk of rod-failure that is unacceptable to many tuners, who therefore decide to upgrade the rods at that point. This failure has happened to many cars - it's a fact.
Your cars engine has definitely got a vastly reduced life-expectancy, thats simply a mechanical fact. That does not mean that it'll blow up this month, next month, or even in 5 years, but it will 'on average' fail far sooner than a stock engine.
A stock Porsche engine is designed so the rods will never bend and that the engine will never blow-up. That is not to say that there isn't a very very small probability of a failure.
The higher the engine is tuned the greater the chance of a failure at any given point and the shorter the expected life of the engine, which is why race engines get rebuilt regularly.
There is clearly a point above which the chance of failure increases dramatically and in this case it's directly related to the strength of the rods. That said you can only observe/predict an expected life and clearly there is a huge randomness around what happens to any individual engine.
If you run 1000nM instead of factory 680nM, you might for example reduce the expected engine life from 20 years, to 3-5 years. However an individual engine might vary between only a few months and some lasting 10 years.
The point is that beyond a certain torque level you introduce a risk of rod-failure that is unacceptable to many tuners, who therefore decide to upgrade the rods at that point. This failure has happened to many cars - it's a fact.
Your cars engine has definitely got a vastly reduced life-expectancy, thats simply a mechanical fact. That does not mean that it'll blow up this month, next month, or even in 5 years, but it will 'on average' fail far sooner than a stock engine.
Banned
Joined: Apr 2011
Posts: 27
From: France
Rep Power: 0
My point is not meant to deride in any way the US tuners, who have in my opinion moved on the game massively from what the Euro-tuners did in terms of proven power and speeds etc. There are many very professional US Tuners I have the highest of respect for.
My point remains the same though, those tuners who have run the cars with high-torque and really hard use (that is typically not found in US Street-driving) have found that they can bend the rods. A stock rod that bends with 600lb ft at Ruf or RS Tuning is exactly the same rod that has bent for cjv and now Champion etc.
Mention has been made of the US tuned cars running in Russia. These are mainly Switzer cars and they have been performing extremely well and lasting on stock rods. Guess why, look at their dynos, Switzer tune their cars to make power, but hold back on the torque. The P800 makes about 800hp, but only about 650lb ft torque. I'd bet thats because Switzer also know that running massive boost in the low/mid-range will easily make the torque, but the rods will not cope if it's used hard.
I used to have a few Nissan GTRs (had all of them 32-35). One of the reasons the legendary RB26 held together so well was that it revved so high, you can make 1000bhp with an engine that only makes 650lb ft, if it can rev to near 9000rpm. A Formula 1 engine makes about 800bhp at 18,000 rpm, but it's peak torque is under 225lb ft ! Great article here: http://www.epi-eng.com/piston_engine..._cup_to_f1.htm
My point remains the same though, those tuners who have run the cars with high-torque and really hard use (that is typically not found in US Street-driving) have found that they can bend the rods. A stock rod that bends with 600lb ft at Ruf or RS Tuning is exactly the same rod that has bent for cjv and now Champion etc.
Mention has been made of the US tuned cars running in Russia. These are mainly Switzer cars and they have been performing extremely well and lasting on stock rods. Guess why, look at their dynos, Switzer tune their cars to make power, but hold back on the torque. The P800 makes about 800hp, but only about 650lb ft torque. I'd bet thats because Switzer also know that running massive boost in the low/mid-range will easily make the torque, but the rods will not cope if it's used hard.
I used to have a few Nissan GTRs (had all of them 32-35). One of the reasons the legendary RB26 held together so well was that it revved so high, you can make 1000bhp with an engine that only makes 650lb ft, if it can rev to near 9000rpm. A Formula 1 engine makes about 800bhp at 18,000 rpm, but it's peak torque is under 225lb ft ! Great article here: http://www.epi-eng.com/piston_engine..._cup_to_f1.htm
Switzer P800 kit is 800 crank hp
SPI made around 680whp on that kit..I believe the Dyno available in the forum.
Both Proto and SPI made mid 800ft/lbs on wheels Alpha 30 kits with no problem.
SPI infamous Sledgehammer made a round 800ft/lbs on wheels
Registered User
Joined: Oct 2008
Posts: 2,321
From: Fastlane USA
Rep Power: 246
It's obviously true that as one increases power the risks of engine failure increase but there are so many mitigating circumstances that contribute to failure that a blanket statement such as "vastly reduced life-expectancy" is overstated, imo. Sure everything can be attributed to "pressure" but it's how the "pressure" is applied that counts. Mitigating risk is the key for a long and healthy motor with big power. That's why you need to get a tuner who really knows what he's doing. Milou's motor, if nothing peripheral breaks down, will run a vastly long time, imho.
