Dinan Suspension Review

Originally Posted by jimefam

It's BMW who must make a compelling case in court not the other way around. The problem comes in the owner not blinking when confronted with such absurd claims. Sure we see things from the consumers side and can understandably be weary of the idea of court and lawyers etc but the reality is the dealer doesn't want those headaches either specially when they know it's their fault and if they take it that far they'll end up eating the repairs anyways plus all the effort and lose a customer. Turbos are less strained with reduced back pressure not the other way around.
Oh and an 8k turbo job? You really think it costs the dealer that?

Please tell how increasing the pressure differential across a turbo makes a turbo less strained.

The lower backpressure post turbine allows the most effective use of the pressure being created preturbine. So when there is low backpressure the turbo is able to more efficiently do work instead of working to overcome said back pressure. That leads to much less lag and allows the turbo to reach it's target boost with less pressure preturbo and allowing the turbine to power the compressor with less total work.

You'd be right if we were increasing the target boost to take advantage of the lower backpressure but were not talking about that were talking about swapping mufflers and running the stock target boost.

Originally Posted by jimefam

The lower backpressure post turbine allows the most effective use of the pressure being created preturbine. So when there is low backpressure the turbo is able to more efficiently do work instead of working to overcome said back pressure. That leads to much less lag and allows the turbo to reach it's target boost with less pressure preturbo and allowing the turbine to power the compressor with less total work.

Turbos are driven by differential pressure. Lowering the back pressure allows for a larger differential pressure. With a larger differential pressure the turbos accelerate quicker maintaining their designed differential pressure. In a simplified form, F=MA, which should make it clear that increased Acceleration results in proportionally increased Force. Again in a simplified form, W=FD, shows there is also increased Work being performed by the turbo. Although these are a transient conditions, it is this peak Acceleration, peak Force, and the peak Work that could easily be explained by any engineer as evidence that the vehicle mods forced the turbos to exceed the design spec for lubrication or component life. I'm not saying it will happen, but it is possible from a Engineer's perspective.

Comparing the Dinan exhaust to the similarly complex (vacuum valve vs electric valve) and similarly priced (both ~$3.6k) Meistershaft (these are not simple axle-back mufflers), the Dinan has the edge due to their refund policy (100% vs 80%) and their warranty (Dinan 4/50 vs. muffler only). If there is any drone in my car, it's being returned.

Originally Posted by jimefam

You'd be right if we were increasing the target boost to take advantage of the lower backpressure but were not talking about that were talking about swapping mufflers and running the stock target boost.

You are correct only if you are talking about any muffler other than Dinan. With Stage 3 being aligned with the Dinan exhaust installation, why wouldn't you expect the target boost to be modified? I would assume the peak horsepower gain (10hp) has little to do with the improved performance associated with the exhaust, but rather they remapped the boost vs rpm to allow for more boost and power at lower rpms to take advantage of the reduced back pressure. Having a Dinan label on the back of your car may be nice, but having integrated tunes and mods are great. Again, as an Engineer, this is a perspective that I can appreciate.

Originally Posted by dunderhi

Turbos are driven by differential pressure. Lowering the back pressure allows for a larger differential pressure. With a larger differential pressure the turbos accelerate quicker maintaining their designed differential pressure. In a simplified form, F=MA, which should make it clear that increased Acceleration results in proportionally increased Force. Again in a simplified form, W=FD, shows there is also increased Work being performed by the turbo. Although these are a transient conditions, it is this peak Acceleration, peak Force, and the peak Work that could easily be explained by any engineer as evidence that the vehicle mods forced the turbos to exceed the design spec for lubrication or component life. I'm not saying it will happen, but it is possible from a Engineer's perspective.

Comparing the Dinan exhaust to the similarly complex (vacuum valve vs electric valve) and similarly priced (both ~$3.6k) Meistershaft (these are not simple axle-back mufflers), the Dinan has the edge due to their refund policy (100% vs 80%) and their warranty (Dinan 4/50 vs. muffler only). If there is any drone in my car, it's being returned.



You are correct only if you are talking about any muffler other than Dinan. With Stage 3 being aligned with the Dinan exhaust installation, why wouldn't you expect the target boost to be modified? I would assume the peak horsepower gain (10hp) has little to do with the improved performance associated with the exhaust, but rather they remapped the boost vs rpm to allow for more boost and power at lower rpms to take advantage of the reduced back pressure. Having a Dinan label on the back of your car may be nice, but having integrated tunes and mods are great. Again, as an Engineer, this is a perspective that I can appreciate.

Your right about it accelerating the turbine faster but as you pointed out that is a transient condition which is more than made up for by the turbine being more effective and needing less pressure preturbo to do the same work. Wastegate opens sooner(since were talking about same target boost) and the turbine builds the same boost with less pressure overall it's easier on the turbo. Turbos are driven by pressure, your not targeting any specific pressure ratio, your statement that the turbine accelerates faster while maintaining it's design pressure ratio is incorrect. It's BECAUSE the pressure differential is increasing that it accelerates faster. The pressure RATIO is increasing but not the actual pressure placed on the turbine its just that it is now more efficiently using it. If you could create a vaccum post turbo that would be ideal as it would allow 100% of the pressure produced by the engine to go towards accelerating the turbine and not on overcoming backpressure. Think of it as driving a car against a head wind, if your target speed is 80mph you'll get there much faster and require less force if the head wind is 10mph vs 60mph. That is the effect of reducing backpressure and while our car in the example would accelerate faster and therefore perhaps place a greater momentary strain on some components once up to speed it will do the same work with less force placed on it. Besides with the turbine accelerating faster what is the worry? That the turbine itself comes apart? I've seen this happen but under incredible pressure on drag cars it's not something we have to worry about. The turbo is designed for the rpms@peak boost and anything below that is gravy.

I brought up the fact that tuning would change things because from what's been reported here your wrong dinan doesn't automatically alter the tune in response to adding the mufflers it's a separate item with a separate charge and because my point was a muffler change is not something they can void your warranty over. A change in boost however is different and not the same as just buying a Dinan exhaust or anyone elses for that matter. Again it has nothing to do with dinan, I think $4k+ installation is insane for any set of mufflers not just Dinans. It's funny but having integrated tunes and mods is the only thing that kept me from buying the dinan tune in the first place. Yes they tune for THEIR mods but say tomorrow you want to put a downpipe on your car? Better hope dinan makes one and comes out with a tune for it because they're not gonna tune your car to your mods. For most that's fine and that's why youve heard me say dinan is good and I recommend it for most but once you bought that dinan tune your tied to what they develop and how they develop it. Another thing is having the work done by the dealer changes the cost dramatically, look at your springs you paid what's the average price for springs(around $500) but you paid almost triple that in installation! Hell you paid upfront for whatever could go wrong(and being that it was just springs nothing ever will) but hey you've got warranty. It's a different viewpoint it ain't wrong but that's why I dont stress the warranty issue.

Originally Posted by jimefam

Your right about it accelerating the turbine faster but as you pointed out that is a transient condition which is more than made up for by the turbine being more effective and needing less pressure preturbo to do the same work. Wastegate opens sooner(since were talking about same target boost) and the turbine builds the same boost with less pressure overall it's easier on the turbo. Turbos are driven by pressure, your not targeting any specific pressure ratio, your statement that the turbine accelerates faster while maintaining it's design pressure ratio is incorrect. It's BECAUSE the pressure differential is increasing that it accelerates faster. The pressure RATIO is increasing but not the actual pressure placed on the turbine its just that it is now more efficiently using it. If you could create a vaccum post turbo that would be ideal as it would allow 100% of the pressure produced by the engine to go towards accelerating the turbine and not on overcoming backpressure. Think of it as driving a car against a head wind, if your target speed is 80mph you'll get there much faster and require less force if the head wind is 10mph vs 60mph. That is the effect of reducing backpressure and while our car in the example would accelerate faster and therefore perhaps place a greater momentary strain on some components once up to speed it will do the same work with less force placed on it. Besides with the turbine accelerating faster what is the worry? That the turbine itself comes apart? I've seen this happen but under incredible pressure on drag cars it's not something we have to worry about. The turbo is designed for the rpms@peak boost and anything below that is gravy.

Yeah, you are almost there in your understanding, but turbos are driven by differential pressure, not by any given inlet pressure. Think of it this way. If you have 30psia at the inlet and 30psia at the outlet, the turbo does not spin. If you have a designed 30psia at the inlet and a designed 20psia at the outlet the turbo now spins as designed. If you have 30psia at the inlet and 15psia at the outlet, there is now a greater differential force that acts upon the turbo blades and the blades will accelerate faster. If the turbo is efficient enough, it will act to lower the dynamic inlet pressure to reach 25psia to maintain the designed differentail pressure.

Originally Posted by jimefam

I brought up the fact that tuning would change things because from what's been reported here your wrong dinan doesn't automatically alter the tune in response to adding the mufflers it's a separate item with a separate charge and because my point was a muffler change is not something they can void your warranty over. A change in boost however is different and not the same as just buying a Dinan exhaust or anyone elses for that matter. Again it has nothing to do with dinan, I think $4k+ installation is insane for any set of mufflers not just Dinans. It's funny but having integrated tunes and mods is the only thing that kept me from buying the dinan tune in the first place. Yes they tune for THEIR mods but say tomorrow you want to put a downpipe on your car? Better hope dinan makes one and comes out with a tune for it because they're not gonna tune your car to your mods. For most that's fine and that's why youve heard me say dinan is good and I recommend it for most but once you bought that dinan tune your tied to what they develop and how they develop it. Another thing is having the work done by the dealer changes the cost dramatically, look at your springs you paid what's the average price for springs(around $500) but you paid almost triple that in installation! Hell you paid upfront for whatever could go wrong(and being that it was just springs nothing ever will) but hey you've got warranty. It's a different viewpoint it ain't wrong but that's why I dont stress the warranty issue.

Dinan sells the mufflers without the tune for guys who don't have Stage 2. If you have Stage 2 (a prerequisite for Stage 3), it would be silly not to get the tune. I agree on the downpipe issue, but the stock downpipe is pretty good, so it isn't high on Dinan's list.

Finally you keep missing the point. The warranty isn't just on the springs, but also all of the other suspension components, like the adjustable shocks, which aren't cheap either.

Originally Posted by dunderhi

Yeah, you are almost there in your understanding, but turbos are driven by differential pressure, not by any given inlet pressure. Think of it this way. If you have 30psia at the inlet and 30psia at the outlet, the turbo does not spin. If you have a designed 30psia at the inlet and a designed 20psia at the outlet the turbo now spins as designed. If you have 30psia at the inlet and 15psia at the outlet, there is now a greater differential force that acts upon the turbo blades and the blades will accelerate faster. If the turbo is efficient enough, it will act to lower the dynamic inlet pressure to reach 25psia to maintain the designed differentail pressure.

The inlet pressure will change some but unless it was a small reduction in backpressure it shouldn't keep the pressure ratio the same. Your saying the same thing I said above, just that you were talking about it's "designed" pressure ratio like maintaining that was the goal but it's not. You want the larger pressure differential for the reasons I detailed before, have you ever seen a turbo'd drag car? They fit the largest downpipe they can for the shortest distance possible for the reasons I've stated. If they could(or we could) somehow create a vacuum that would be best. There is no desired pressure ratio you simply compromise between sound, volume, packaging and appearance. I love how you skipped over the rest of the post by diverting to a technicality. Reminds me of when we were going back and forth about intake inlet pressure and you were saying the lack of high speed was the difference between Dinan's claims and everyone elses results. I had a good lol the other day when reading the 458 italia has 565hp at low speeds but 570hp at 180mph and above! Lol it picks up 5bhp going 2.5x's faster than most of us will go regularly. And that's on an NA car where the inlet pressure has much more effect than a turbo'd engine and the car is designed to take max benefit from said pressure. On the spider because of packaging they couldn't use a forward facing intake and guess what? It lost just the 5bhp and produces the same accel numbers as the italia even though it's 50lbs heavier(except for top speed which I think the italia is 2-3mph faster) don't always believe the hype

Dinan sells the mufflers without the tune for guys who don't have Stage 2. If you have Stage 2 (a prerequisite for Stage 3), it would be silly not to get the tune. I agree on the downpipe issue, but the stock downpipe is pretty good, so it isn't high on Dinan's list.

Finally you keep missing the point. The warranty isn't just on the springs, but also all of the other suspension components, like the adjustable shocks, which aren't cheap either.

The point is they cannot just deny your claim because you made a change. Even if your turbo theory above was correct it would be one of many reasons a turbo can fail they need to PROVE it was that reason that it did. If your shocks go bad tomorrow it may be because of the springs and it may not but they must show it was the direct cause and getting that would probably take more effort than it would to swap out the shocks(specially when it was most likely NOT the springs or muffler that would cause a failure). It's like the Ferrari example above we can go back and forth forever but at some point common sense has to factor in here doesn't it? Please post up someones turbo or engine that was damaged because he changed mufflers? And if were talking real world why would someone spend probably $4,500 on mufflers while having no tune instead of spending less money and seeing huge benefits? Either way the tune could have atleast been included and if you don't or can't use it so be it but charging $200 to get the benefit out of a $4500 purchase is just silly IMO.

Originally Posted by jimefam

The point is they cannot just deny your claim because you made a change. Even if your turbo theory above was correct it would be one of many reasons a turbo can fail they need to PROVE it was that reason that it did. If your shocks go bad tomorrow it may be because of the springs and it may not but they must show it was the direct cause and getting that would probably take more effort than it would to swap out the shocks(specially when it was most likely NOT the springs or muffler that would cause a failure). It's like the Ferrari example above we can go back and forth forever but at some point common sense has to factor in here doesn't it? Please post up someones turbo or engine that was damaged because he changed mufflers? And if were talking real world why would someone spend probably $4,500 on mufflers while having no tune instead of spending less money and seeing huge benefits? Either way the tune could have atleast been included and if you don't or can't use it so be it but charging $200 to get the benefit out of a $4500 purchase is just silly IMO.

Installed with tune is $4200 for real gains. No one else does it at any cost right now.

Sent from my ADR6350 using Bimmer

Originally Posted by dunderhi

Installed with tune is $4200 for real gains. No one else does it at any cost right now.

Sent from my ADR6350 using Bimmer

I said $4500 based on a price of $3700 + tax which here would be $260 for a total of $3960 just for the system. Now add in the $280 for the tune(which probably comes with it's own labor cost on top lol) and your at $4240 plus install which should be like $200 which means they'll charge $600(I mean they charged $1400+ for spring install) and like I said earlier probably charge you for installing the tune. Looks to me like $4500 was being conservative. But you've got warranty.

Originally Posted by jimefam

I said $4500 based on a price of $3700 + tax which here would be $260 for a total of $3960 just for the system. Now add in the $280 for the tune(which probably comes with it's own labor cost on top lol) and your at $4240 plus install which should be like $200 which means they'll charge $600(I mean they charged $1400+ for spring install) and like I said earlier probably charge you for installing the tune. Looks to me like $4500 was being conservative. But you've got warranty.

Sorry, but I'm not trying to cheap-out on my mods to create a Frankencar that may or may not have any real gains.

I've already got my quote for the exhaust and tune. Nice try for being conservative.

Sent from my ADR6350 using Bimmer

Originally Posted by dunderhi

Sorry, but I'm not trying to cheap-out on my mods to create a Frankencar that may or may not have any real gains.

I've already got my quote for the exhaust and tune. Nice try for being conservative.

Sent from my ADR6350 using Bimmer

It's not about price it's about value, besides for me it's about being able to get what I want out of the car. I plan on modifying the car pretty heavily and as noted before I don't want to tie myself to the progress of any one company. If at some point a performance mod you want comes out but isn't Dinans there goes your tune. I take it back $4200 is a steal lol. On a serious note I had a question, how did they do your springs when online it says it's not compatible with Xdrive?

Originally Posted by jimefam

It's not about price it's about value, besides for me it's about being able to get what I want out of the car. I plan on modifying the car pretty heavily and as noted before I don't want to tie myself to the progress of any one company. If at some point a performance mod you want comes out but isn't Dinans there goes your tune. I take it back $4200 is a steal lol. On a serious note I had a question, how did they do your springs when online it says it's not compatible with Xdrive?

The springs are working great with my xDrive F10, so I'm not sure why they wouldn't be compatible, unless maybe the install is much too intensive.

Sent from my ADR6350 using Bimmer

Originally Posted by dunderhi

The springs are working great with my xDrive F10, so I'm not sure why they wouldn't be compatible, unless maybe the install is much too intensive.

Sent from my ADR6350 using Bimmer

Good to hear, I thought there must of been something different as iirc no other springs are available for the X drives.

Originally Posted by dunderhi

The springs are working great with my xDrive F10, so I'm not sure why they wouldn't be compatible, unless maybe the install is much too intensive.

Sent from my ADR6350 using Bimmer

Thanks for the information. It was a good question because the Dinan website says that they are not compatible with xDrive. Nice to hear that they work.

Originally Posted by jimefam

Good to hear, I thought there must of been something different as iirc no other springs are available for the X drives.

AC Schnitzer lists their springs as being the same model number for both the 550xi & 550i, but they do have a longer install time (5.8hrs vs 4.5hrs) for the xi. So I'm not sure why Dinan is make that distinction. A quick email will have an answer from Dinan on Monday.

Originally Posted by dunderhi

AC Schnitzer lists their springs as being the same model number for both the 550xi & 550i, but they do have a longer install time (5.8hrs vs 4.5hrs) for the xi. So I'm not sure why Dinan is make that distinction. A quick email will have an answer from Dinan on Monday.

:thumbsup:

I just picked up a 550i M-Sport over the weekend, but have been lurking around for a few months on the 5 series forum looking for feedback on the various Dinan products. I hope to get as many Dinan goodies I can. For the suspension, I am still on the fence regarding their springs. I have yet to see any pics of a car with 20in wheels with their springs until today. On Dinan's website, they now have an image of a 550i on 20in HRE's however they are using a 35 series tire in the rear. I had thought that if we jump to a 20in we should use a 30 series tire (Plus 1 upgrade). Won't a 35 series tires in rear negatively effect acceleration and lessen the drop? Perhaps they are going this route so that the gap between the tire and fender is smaller. They are also going with some wide tires as well (Front: 275 series & Rear: 295 Series). Thanks in advance to those who chime in....

Originally Posted by SMA335i

I just picked up a 550i M-Sport over the weekend, but have been lurking around for a few months on the 5 series forum looking for feedback on the various Dinan products. I hope to get as many Dinan goodies I can. For the suspension, I am still on the fence regarding their springs. I have yet to see any pics of a car with 20in wheels with their springs until today. On Dinan's website, they now have an image of a 550i on 20in HRE's however they are using a 35 series tire in the rear. I had thought that if we jump to a 20in we should use a 30 series tire (Plus 1 upgrade). Won't a 35 series tires in rear negatively effect acceleration and lessen the drop? Perhaps they are going this route so that the gap between the tire and fender is smaller. They are also going with some wide tires as well (Front: 275 series & Rear: 295 Series). Thanks in advance to those who chime in....

Yes this seems really odd. Also 35 on a 275 has a higher radius than 40 on a 245. So both front and rear tires are taller. I don't think the height is as big of an issue as the width. Some people on this board are running 7 series wheels and tires with no problem (275/35/20 on rear), but the width seems a stretch to me.

Originally Posted by SMA335i

I just picked up a 550i M-Sport over the weekend, but have been lurking around for a few months on the 5 series forum looking for feedback on the various Dinan products. I hope to get as many Dinan goodies I can. For the suspension, I am still on the fence regarding their springs. I have yet to see any pics of a car with 20in wheels with their springs until today. On Dinan's website, they now have an image of a 550i on 20in HRE's however they are using a 35 series tire in the rear. I had thought that if we jump to a 20in we should use a 30 series tire (Plus 1 upgrade). Won't a 35 series tires in rear negatively effect acceleration and lessen the drop? Perhaps they are going this route so that the gap between the tire and fender is smaller. They are also going with some wide tires as well (Front: 275 series & Rear: 295 Series). Thanks in advance to those who chime in....

Let me know what you decide on 20" wheels, as this is what I plan to add to my '12 550i M Sport, together with springs and possible tuning (if safe, etc.). I am planning on Dinan (on sale) but am keeping an open mind.

Originally Posted by Stealth8

Let me know what you decide on 20" wheels, as this is what I plan to add to my '12 550i M Sport, together with springs and possible tuning (if safe, etc.). I am planning on Dinan (on sale) but am keeping an open mind.

Will do....I am leaning towards some HRE wheels. Lon of HRE recommends 20 X 9 wheels with 255/35/20 tires for the front and 20 X 10.5 wheels with 285/30/20 tires (Pilot Super Sport tires). I really wish someone with 20in wheels/tire Plus 1 setup posts some detailed pictures with Dinan springs. Apparently there is no one out there yet or they are being shy to post.

Originally Posted by SMA335i

Will do....I am leaning towards some HRE wheels. Lon of HRE recommends 20 X 9 wheels with 255/35/20 tires for the front and 20 X 10.5 wheels with 285/30/20 tires (Pilot Super Sport tires). I really wish someone with 20in wheels/tire Plus 1 setup posts some detailed pictures with Dinan springs. Apparently there is no one out yet or they are being shy to post.

That's the wheel/tire choice I want to run but am waiting for someone to sell M5 20s

I'm running 20 X 9 with 245's front and 20 X 11 with 305's in the back.

I am also running 20x8.5 255/35/20 and 20x10.5 285/30/20

Originally Posted by Turo37765

I am also running 20x8.5 255/35/20 and 20x10.5 285/30/20

Are you lowered with dinan springs?

Not in that picture. But will be by end of this month. I'll repost pics. But I just put the stocks on for the spring install. I want it to be perfect with the stock set up. Then ill swap rims again if it continues bit to snow here in NY

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