# Is tuning bad for engine?



## Chadley (Sep 1, 2012)

First off, I am not a mechanic so I may be completely off base but I do understand mechanical stresses. I have read many threads about tuning including claims of improved mileage and performance. My question is how can this not harm the engine? Additional power equals additional stress on all of those moving parts. Somewhere in all of those parts is a weakest link and the stress will eventually cause failure of said part. The extra power is tempting but I'm afraid of wrecking my car for the sake of getting that extra torque. 
I would appreciate it if there is anyone who can comment on this with expertise in this area. Is anyone out who tuned their bimmer and had any problems related to it? I plan on keeping this car for the long haul so I can live with the power "as is" but I am curious.


----------



## Flyingman (Sep 13, 2009)

I chose to live with "as is" after serious consideration of a tune.

I'm a Mechanical Engineer, now a Risk Engineer, so I have my own educated opinion about this.

First, engineers design everything with a factor of safety. How much is a major judgement call based on cost, reliability, efficiency, safety, etc. I'm sure our engines have considerable margin to crank out more power if desired.

Clearly there will be some reduction in safety factor when you do this. To know for sure you would have to test and analyze. I don't think any tune increases actual rpm, so pure rotational mechanical forces should not be affected by a tune.

The main thing that a tune does is allow more air/fuel into the combsution chamber which allows more power in a given stroke, i.e. more acceleration but not necessarily higher rpm. The increased power is due to higher MEP (mean effective pressure) which of course translates to greater pressure and stress on the piston, gudgeon pin, skirt, connecting rod, big end bearing, crankshaft pin and main bearing. This is where the factor of safety kicks in, hopefully you have enough.

This higher power will also increase the load on the oil, both in pressure and temperature. You will reduce the clearance between the wear parts that are lubricated and cooled by the oil. This could possibly increase wear, and higher temps on the oil may oxidize it faster. Thus the reason many folks that track add larger oil coolers.

Another important factor is that our engines are designed to meet gov't efficiency and emission requirement. They are tuned to the desired output which may not be the most efficient or highest power. A tune will most likely affect the efficiency and/or emissions. 

If you want to race, do you really care about this?

I chose not to mess with the tune for many reasons but honestly I'm pretty satisfied with the car as is.


----------



## Chadley (Sep 1, 2012)

Thanks for your insight Flyingman. I figure if the tires spin already from the existing power, I will only end up spinning them more frequently if tuned. It sure would to nice to see what the extra power would be like though.


----------



## 335dFan (Nov 8, 2012)

Chadley said:


> Thanks for your insight Flyingman. I figure if the tires spin already from the existing power, I will only end up spinning them more frequently if tuned. It sure would to nice to see what the extra power would be like though.


From a one person sample (me), the boost from the JBD (@ 100%) is mainly felt at speeds above the legal limit. However, even from a standing start, a JBD equipped D will pull away from a stock D. I did that experiment with my buddy Former Rotor. He had the JBD and I did not at that time. If that little bit of extra grunt is not that big a deal to you, then it is probably not worth the money. Although the money is not much for the JBD. I have never raced against a ECU-tuned D, so I cannot compare, nor have I driven one.

I did a BMW CCA HPDE track day both without and with a JBD. In both cases I was definitely not embarrassed to be behind the wheel of the D. On the contrary, the D was probably rather chagrined that I was behind the wheel.


----------



## DaveN007 (Oct 4, 2013)

Chadley said:


> First off, I am not a mechanic so I may be completely off base but I do understand mechanical stresses. I have read many threads about tuning including claims of improved mileage and performance. My question is how can this not harm the engine? Additional power equals additional stress on all of those moving parts. Somewhere in all of those parts is a weakest link and the stress will eventually cause failure of said part. The extra power is tempting but I'm afraid of wrecking my car for the sake of getting that extra torque.
> I would appreciate it if there is anyone who can comment on this with expertise in this area. Is anyone out who tuned their bimmer and had any problems related to it? I plan on keeping this car for the long haul so I can live with the power "as is" but I am curious.


Mass production autos are generally engineered to tight $ tolerances.

Think about it. The car is warranted against major mechanical failure for the first 4 years or 50,000 miles, for example. The goal of the car company is to deliver enough performance to get you to buy the car, but not so much that it increases costs.

Increasing power output absolutely statistically increases the likelihood of a failure, all other things being equal.

But...there are some things that you can do...like tune the car so that it will not just run *better* on 91 octane or greater, but *require* 91 octane or better to not damage the engine. As long as you don't run 87 octane...you are OK. Car manufacturers can't put a car out there that will die on 87...even when they tell you to run on 91. They have to play it safe. (Obviously not a diesel example.)

Less constrictive exhaust and an ECU tune are pretty mild. Adding forced induction, or recalibrating to increase boost is more significant.

I supercharged my 1998 E36 M3 (paid Dinan dearly to do it right and California legal) when it was new and had zero issues. (Meaning I had a rare CEL that would clear itself.) That took the car from 240 to 350HP +/-. I sold after 7 years and about 50k miles. Who knows if the long term effects were felt by the very happy guy who bought my car for half of what I put into it.

Personally, after modding several BMWs and Porsches over the years...I am just tired of dealing with the nuisance factors. The check engine lights. Problems with getting a car smogged, etc.

I'd say as a rough rule of thumb, you can easily get 10,20,even 30 percent more power out of your car without hurting it...but the computer nanny systems in today's cars might not let you get away with it.

Just remember that the mod biz is just a notch above the drug and prostitution biz in terms of your relationship to the guys who sell you stuff for your car. You really don't know what you are getting, and they are rarely in a position to support you if their products blow up your car. Since you sort of feel shady and guilty doing something you kind of feel like you shouldn't be doing in the first place, they have you by the proverbial "short hairs".

Whatcha gonna do? Call the cops and tell them your drug dealer cheated you? :rofl:

One final thought:

1 factory stock HP seems to equal 1.75 modded HP 

This video is a great example of this phenomenon. Dinan BMW _*should be quicker*_ than stock newer car.


----------



## Hoooper (Jun 17, 2013)

BMW has taken this engine (with an added third turbo) to 376 hp and 546 lb ft in a production car, the JBD doesn't get you to those numbers and neither do and of the other tunes so you are good to go

http://www.caranddriver.com/reviews/2013-bmw-m550d-xdrive-first-drive-review


----------



## floydarogers (Oct 11, 2010)

Hoooper said:


> BMW has taken this engine (with an added third turbo) to 376 hp and 546 lb ft in a production car, the JBD doesn't get you to those numbers and neither do and of the other tunes so you are good to go
> 
> http://www.caranddriver.com/reviews/2013-bmw-m550d-xdrive-first-drive-review


Note that the article also says: "...BMW has strengthened the engine... and uses a fuel pump good for 31,000 psi..." So, no, you're not "good to go".


----------



## Hoooper (Jun 17, 2013)

Didn't see that part. The whole idea is a bit silly though, the body of experience on this subject is gigantic, how many cases of mild tuning have been linked to failed engines? I really can't think of any platforms where that has been the case. There are plenty of cases where people have gone overboard with mods and resulted in melted pistons, bent rods, etc but mild tuning (JBD is undoubtedly a mild tune)? Never heard of an issue. I think if you're going to be making assumptions on how a company designs their engines and tunes you also need to assume that they make decisions with the understanding that they will get tuned in the aftermarket.

What kind of difference are you really looking at anyway? You have a motor that's good for several hundred thousand miles and worst case when responsibly tuned is good for a couple hundred thousand?


----------



## F32Fleet (Jul 14, 2010)

Hoooper said:


> Didn't see that part. The whole idea is a bit silly though, the body of experience on this subject is gigantic, how many cases of mild tuning have been linked to failed engines? I really can't think of any platforms where that has been the case. There are plenty of cases where people have gone overboard with mods and resulted in melted pistons, bent rods, etc but mild tuning (JBD is undoubtedly a mild tune)? Never heard of an issue. I think if you're going to be making assumptions on how a company designs their engines and tunes you also need to assume that they make decisions with the understanding that they will get tuned in the aftermarket.
> 
> What kind of difference are you really looking at anyway? You have a motor that's good for several hundred thousand miles and worst case when responsibly tuned is good for a couple hundred thousand?


You may not. I suspect many of the heavily tuned cars are unloaded at lease end or prior to termination of factory warranty. OR just the shame of screwing up your ride prevents people from telling the public about it.

IMO this is why I would never buy a used 335i. Too many turners thrashing their leased car.

BMW could've put the hammer down on the tuner if they wanted.


----------



## Hoooper (Jun 17, 2013)

BMWTurboDzl said:


> You may not. I suspect many of the heavily tuned cars are unloaded at lease end or prior to termination of factory warranty. OR just the shame of screwing up your ride prevents people from telling the public about it.
> 
> IMO this is why I would never buy a used 335i. Too many turners thrashing their leased car.
> 
> BMW could've put the hammer down on the tuner if they wanted.


heavily tuned is not the same as mildly tuned though, thats my point. Especially with JBD or the other boxes, those are pretty mild tunes. They dont even affect the boost levels. Once you start talking about heavily modified thats a whole different world because you have to consider what they were doing, how they drove, did the have a clue WTF was even going on? Ive definitely seen heavily modded cars that were beat to crap because of it, but thats really the same category as guys who are going through engines because of it. JBD came out of beta more than 4 years ago, do we really think if its going to cause any serious issues it wouldnt have done so already?

I would be inclined to be more concerned with the life of the shocks and bushings because it is so much easier to be going way too fast once tuned and those are actually a "short" term wear item


----------



## floydarogers (Oct 11, 2010)

Hoooper said:


> ..., how many cases of mild tuning have been linked to failed engines? ...but mild tuning (JBD is undoubtedly a mild tune)? Never heard of an issue.


I'd say a JPD at 60% or so would qualify... But if I were modding my 'd, I'd start with something I could actually use, like an LSD, rather than more power/torque (lot of snow driving in my future).

The factory tune is a balance of performance, longevity, emissions, and a couple of other things. I think of it as the minimal point of those functions (mathematical concept); you change one (hp/tq) and you lose something else.


----------



## DaveN007 (Oct 4, 2013)

Let me toss this out there for thought...

It looks like "the factory" screwed up *the tune* on 335d cars *BIG TIME*.

Some speculate that our cars are "over-torqued" :yikes: by design...and this massive amount of power means that we can't run the engines under the load needed to keep carbon build up from being a problem. Not in the US, anyway.

It is just too easy to putter around just above idling and reach the speeds we can legally reach.

Consensus seems to be that this is bad for diesels.

This may be why the X5 version (heavier...requires more loading of the engine to get around each day) seems to have less of an issue with carbon build up to date.

:dunno:

I'll bet that the 328d hamster-in-a-wheel motor won't have these issues as it is flogged mercilessly.

Maybe the dream of powerful AND emissions acceptable diesel is dead. 

If I have to drive my 335d in a way that yields fuel economy that is worse than an equivalently powerful petrol car to keep it from dying after 60k miles...:banghead:


----------



## F32Fleet (Jul 14, 2010)

DaveN007 said:


> Let me toss this out there for thought...
> 
> It looks like "the factory" screwed up *the tune* on 335d cars *BIG TIME*.
> 
> ...


Naw. It's just the typical BMW conundrum. Generally people who can afford these cars do not live in areas where they can use the power as intended. They live in densely packed cities.

Who the hell buys a 335d for mpgs? It wasn't built that way. The car was built to run and get decent MPG in the process.


----------



## DaveN007 (Oct 4, 2013)

BMWTurboDzl said:


> Who the hell buys a 335d for mpgs? It wasn't built that way. The car was built to run and get decent MPG in the process.


You have "Fuelly" in you signature :rofl:

The difference is that if I drive my brother's F10 M5 around town and on the highway at legal speeds, I don't cause the car to degrade to a point where I effectively cause $10k worth of damage to the engine at 50k miles.

My Porsche will hit 60mph in just over 4 seconds. Driving it at 65mph and 27mpg isn't "bad" for the the car.

"Built to run" ? What does that mean? :dunno:

I am at WOT in my d at least a few times every time I get behind the wheel, FWIW.


----------



## F32Fleet (Jul 14, 2010)

DaveN007 said:


> You have "Fuelly" in you signature :rofl:
> 
> The difference is that if I drive my brother's F10 M5 around town and on the highway at legal speeds, I don't cause the car to degrade to a point where I effectively cause $10k worth of damage to the engine at 50k miles.
> 
> ...


Oh that M5 will need the valves cleaned. No way around intake valve deposits and BMW direct injection. In addition just like Porsche, you'll find that many of the higher HP BMW's do develop problems due to excessive low speed urban driving.

My having a fuelly signature doesn't mean I'm preoccupied with MPG alone. I would've bought a TDI if I were. When road tripping I routinely drive over 80 mph. Hell I averaged 70 mph on a trip to Biloxi not all that long ago. Thats an average on a 4 hour drive.

If you're worried about carbon Google it along with E320/350 or VW TDI. We're not alone.

You're right about the 4 cylinder diesel. It may not require as much servicing with regards to carbon.


----------



## moejav (May 11, 2012)

There is a company in Toronto Ontario area that offers a mild tune, adds like an extra 50 hp, as well it should also increase mileage, one of the best ways to get better mileage and a bit more power is to do an EGR delete, I would only recommend doing an EGR delete once you're vehicle is out of warranty... it will reduce your risk of carbon buildup in the intake manifold and cylinder head... it will also help with fuel efficiency etc...


----------



## 335dFan (Nov 8, 2012)

moejav said:


> There is a company in Toronto Ontario area that offers a mild tune, adds like an extra 50 hp, as well it should also increase mileage, one of the best ways to get better mileage and a bit more power is to do an EGR delete, I would only recommend doing an EGR delete once you're vehicle is out of warranty... it will reduce your risk of carbon buildup in the intake manifold and cylinder head... it will also help with fuel efficiency etc...


What if you put a JBD on top of such a tune?

Sent from BimmerApp mobile app


----------



## moejav (May 11, 2012)

Not really sure about that... Renntech offers an aggressive tune, they're down near Miami FL I'm looking at perhaps doing a jbd with meth injection and a quaife lsd in the near future perhaps... I was going to do a EGR delete as well, but have a 2 year warranty on the motor now


----------



## Axel61 (Mar 10, 2011)

Moe RENNtech usually caters MILD tunes BUT can go aggresively if the owner so desires but will sign a paper not holding RENNtech liable cause of the tune. I have had RENNtech for 10 yrs on both my cars and NEVER had CEL's come up. If you want a badass tune request it to whomever you fill comfortable with and take a risk, life is a risk anyway!!


----------



## moejav (May 11, 2012)

Axel61 said:


> Moe RENNtech usually caters MILD tunes BUT can go aggresively if the owner so desires but will sign a paper not holding RENNtech liable cause of the tune. I have had RENNtech for 10 yrs on both my cars and NEVER had CEL's come up. If you want a badass tune request it to whomever you fill comfortable with and take a risk, life is a risk anyway!!


:thumbup: If I had not gotten a brand new engine with a 2-year warranty I'd be getting a RennTech tune, most likely still getting an LSD with them


----------



## moejav (May 11, 2012)

I believe that auto manufacturers are very conservative when they build and dial a car in. I believe that cars that are turbo'd from the factory are more tune-able than normally aspirated vehicles. Such as increasing boost a tad on a car, so in my opinion some mild tuning isn't bad for a car!!


----------



## jfxogara (Oct 26, 2012)

There is an impulse to tinker and improve, hard to deny that. But in an age when a Ford Focus sport model has more hp than an 1993 Mustang Cobra, I think I'll just find some way to live with my measly 275 hp and 428 lb/ft of torque.


----------



## moejav (May 11, 2012)

jfxogara said:


> There is an impulse to tinker and improve, hard to deny that. But in an age when a Ford Focus sport model has more hp than an 1993 Mustang Cobra, I think I'll just find some way to live with my measly 275 hp and 428 lb/ft of torque.


you know, a quick tune and you got over 320 hp, and 500 lb. ft. torque!! just sayin' of course you don't want to do that until after factory warranty is up but still... also some things like the carbon build-up problem, which is directly related to the EGR and DEF, with some minor tinkering you make those go away and the car is breathing and running a lot better as well. I'm not saying that stock isn't fun to drive because it is, but I don't plan on spending another $5K to have the head removed and cleaned and replace the intake manifold if I can help it.


----------



## DaveN007 (Oct 4, 2013)

moejav said:


> ...you know, a quick tune and you got over 320 hp, and 500 lb. ft. torque!! just sayin' of course you don't want to do that until after factory warranty is up.../QUOTE]
> 
> When your car is under warranty, it is very, very hard for the manufacturer to deny coverage. They have to be able to prove that the "tune" caused *THE* problem you are asking them to fix.
> 
> ...


----------



## F32Fleet (Jul 14, 2010)

DaveN007 said:


> moejav said:
> 
> 
> > ...you know, a quick tune and you got over 320 hp, and 500 lb. ft. torque!! just sayin' of course you don't want to do that until after factory warranty is up.../QUOTE]
> ...


----------



## Hoooper (Jun 17, 2013)

BMWTurboDzl said:


> True but who knows. I would think with out cars it is the injectors that would go first from the additional pulses adding more fuel. HPFP maybe next. DPF third.


I dont think any of the tunes are adding pulses, just changing pulse length (with DDE tunes) or changing rail pressure (with the box tunes)


----------



## jbb007 (Dec 10, 2021)

Thank you this is very helpful. I just learned deep into my due diligence that a e36 M3 with 60k miles I am planning to buy had a tuner and cold air intake but they were replaced by the seller with OEM parts recently. I usually not looking buy M's with modification for obvious reason like wear/tear but good stock is very low as I am sure your know. Do you know of ways to test if either has damaged the engine? Any advice would be helpful.



Flyingman said:


> I chose to live with "as is" after serious consideration of a tune.
> 
> I'm a Mechanical Engineer, now a Risk Engineer, so I have my own educated opinion about this.
> 
> ...


----------



## ghpup (Nov 19, 2008)

jbb007 said:


> Thank you this is very helpful. I just learned deep into my due diligence that a e36 M3 with 60k miles I am planning to buy had a tuner and cold air intake but they were replaced by the seller with OEM parts recently. I usually not looking buy M's with modification for obvious reason like wear/tear but good stock is very low as I am sure your know. Do you know of ways to test if either has damaged the engine? Any advice would be helpful.


You may want to post this in the M3, or e36 forums. While you may see a great deal of 'tuning' for diesel engines, perhaps more than gas, I believe the tunes are very different, though the objective is always to get more performance. People have been modifying M cars for a very long time. You're likely to get a more informed opinion from an M focused forum.


----------



## lgr122 (Aug 8, 2012)

Basically, if it's just improved program for car which is stock, then it probably doesn't hurt much. 

But it's always question of, how far do you want to go? 

Lower power is generally safet for the car, parts wear less and even chance for accident is bit lower.


----------



## Doug Huffman (Apr 25, 2015)

Diesel burns slower than gasoline. Diesel crank throws and connecting rods are longer than gasoline. Diesel compression ignition engines burn in large excess of oxygen. Diesel compression is about as high as extant metallurgy allows.

One might increase the volume of fuel injected but that will cause only higher bottom end pressures wasting energy.


----------



## lgr122 (Aug 8, 2012)

Doug Huffman said:


> Diesel burns slower than gasoline. Diesel crank throws and connecting rods are longer than gasoline. Diesel compression ignition engines burn in large excess of oxygen. Diesel compression is about as high as extant metallurgy allows.
> 
> One might increase the volume of fuel injected but that will cause only higher bottom end pressures wasting energy.


Diesel is easier to tune up.
Two things, should add fuel and should add blow. But how much it can hold? Same like with gasoline engines, older ones were able to hold more before they explode, newer ones are closer to the edge already from factory.

Edit: Answer to the question, YES, tuning is bad for engine always. It's just that, rest of the car might die before your engine, and then it didn't hurt, if you enjoyed bit more power before your car died.


----------

