mjgroves

Hello all!

I am a new owner of a SRT6, which I have come to understand has the same AMG 3.2L supercharged engine found in your MB C32's. The crossfireforum website has been FUBARed for over 3 months now and I got fed up trying to wait to register so I'm hoping I can find a home here! Performance wise, I'm coming from a 2.4L stratus (4-cyl). So you can imagine how much of a kick in the pants the SRT6 is for me. I love nearly everything about the car, but sadly I have been infected with the power bug... and I need more.

Due to the rarity of the SRT6 (only ~2000 ever made), I also want to save the car for a long time, with the ultimate goal of displaying it as a showcar many years down the road. It's in excellent condition and has only 8,000 miles on it. I know many love it or hate it, so lets just get past the looks and focus on the internals.

After a bunch of research, I determined that the pulley-intake-ECU tune was the way to go for my car. Seems that this is the absolute best bang for the buck to gain a good 50-60HP. The intake seems to be a great performance mod due to the overly restrictive nature of the stock intake. I'd gain a tad in fuel economy and a potential 20-25 HP from it. I've never heard of an engine (my stratus with 125k miles included) suffering any undue stress or decrease in life/reliability due to an intake. The ECU tune also seems like an excellent option. Not only are there no extra parts, but it'll be done by a well respected company who has done countless hours of research. I like these mentioned modifications because of the simple fact that you are "unlocking" hidden power that's already there. The stock air intake is MADE to be restrictive in order to throttle power, for emissions or otherwise. It's to my understanding that it's the same for the ECU. It's not that the engine is unable to handle this extra performance... it's the fact that laws, standards, marketing or whatever impacted these decisions.

The pulley is where my real area of concern lies. This is something that scares me perhaps because I don't know much about it. There are many types of pullies on the market and I am not hoping to rehash the "crank vs SC" pulley discussion here. What I am looking for is an answer to the question of how reliable our IHI superchargers are at these elevated RPM levels. I have read that the stock supercharger runs 12,180 RPM MAX and the lowest offering from LET (the 178) automatically pushes that number up to the 14,460 RPM range. Thats an almost 20% increase in the rpm level. On top of that, based on some additional research it looks like 15,000 is the max RPM level for the SC.

So my first question is, why didn't the tuners decide to go for more conservative numbers, such as 165, 175, 185? It seems like 178, 181, and 185 are awfully close together and clustered "dangerously" close to the max RPM level. Why is this? Why are we playing closer to the edge of the cliff when we can spread it out more? Are they really that confident that the pullies are not reducing reliability, or is this more of a "more power power power at whatever cost" type of deal? If something were to fail here, would it be the supercharger or the engine not being able to handle the additonal power of these three mods? What is the weakest link?

I believe I saw a post by loungin (Eurocharged prez?) claiming "oh I have driven over 30,000 miles with the 185mm pulley with no problems". Doesn't anyone else find this a little unsettling? 30,000 miles is NOTHING in terms of how long modern engines are supposed to last (250,000 miles anyone). Before anyone states the obvious here "oh if you are that concerned with reliability then keep the car stock", keep in mind that I know that any performance modification could potentially negatively impact the longevity of the engine. But I just want to know if this is a 100% to 98.9% reliability impact or a 100% to a 70% reliability impact. Hard to measure, I know, but I'm just looking for thoughts here.

I don't know much about boosting, only as much as I've been able to gather from a bunch of research both here and on crossfireforum. So if im looking at this the wrong way, please let me know.

Thanks!

gt4awd

I'm surely not the best one to answer your questions, but I will give my input on larger crank pulleys. This is mainly what I worry about... The Code3 supercharger pulley I would consider a standalone upgrade. Meaning you're only running higher RPM on the supercharger itself. It would appear it's capable of handling these higher RPM levels as there are little reports of the supercharger giving out on modified M112K engines. Is there increased wear? Of course to a certain extent there will be. To what extent I do not know, and doubt anyone does.

With a larger crank pulley you are running higher RPM on all pulleys. You're not just compressing more air with the supercharger. You're running the A/C compressor, alternator, power steering, and coolant pump faster. Around 5k miles after installing the 185MM my power steering pump failed when the bearings gave out. Can I give blame to the 185MM alone? No, but I have a feeling it contributed to failure of the pump... There's a big problem with the OE supercharger idler giving out especially quick running larger crank pulleys. Pop the hood, and compare that idler to the size of the alternator pulley. What's that spinning at higher RPM? I'm really surprised a company hasn't come out with a kit similar to the pulley saver from NeedsWings that increases the size of these other belt component pulleys to bring them back into spec.

I could be completely wrong here, and sounding like an idiot. So anyone feel free to correct me if I am wrong. I do believe a larger crank will cause faster component failure though...

mjgroves

gt4awd, that is an excellent point you brought up. In fact, I've often wondered why anyone would abandon modifying the SC pulley in favor of the crank pulley setup.

If I had to make a best guess, I'm assuming that there are limitations of how small you can go with the SC pulley, whereas there is no limitation as far as how large you can make a crank pulley. Hence, the tradeoff is in favor of more performance rather than the chance of having some of the accessories fail.

Now that you mention it, I really havent seen any posts about supercharger failure, aside from a member from crossfireforum mentioning that his supercharger seized (?). But I'm fairly certain he was running a 192mm pulley. You may be on to something here.

I greatly appreciate your response. Hopefully we can get some additional insight on the topic! Anyone care to chime in?

EDIT: One other thing gt, I looked at your sig and noticed you're still running the 185. Did you decide to stick with the 185 because you cant live without the power or because you think reliability wont be that much of a concern? Or both?

gt4awd

I drank too much, but let's see if I can get some words in here... I agree modification of the supercharger pulley itself has it's limitations. You will even find the people getting really serious stack an overdrive crank with the smaller supercharger pulley. Both have there limitations. You do also reach a point where the supercharger reaches its efficiency point, and can no longer compress more. I think this has to do with the additional heat generated. I'm going to stay with the 185MM because of the amount invested into my setup. It wasn't cheap... Not to say that's the only reason. I'm willing to risk these failures for the increase in horsepower, and torque. You're STR has very low mileage, and you probably won't have to worry about component failure as much as I do...

Biscuit

This made my lol, heh. Thanks.

loungn14

You are correct in your thinking. There are certain maps in the code that do limit torque etc. Modifying those as well as changing things like timing, fueling etc does unlock a lot of the potential of the engine. The AMG Engineers are on the safe side, and even cripple some of the power of the engine between models. It’s hard to sell a C63 that has more HP then an E63 no? lol There are also a lot of tuners out there, just do your homework.

They are very close together in terms of size. But, there is a great deal of difference between the pullies as far as power is made. (20-30hp)

So for more clarification, you know the amount of SRT6’s produced. The same is true with the C32’s. (they are more rare then the srt’s nowadays) Now, out of the handful of cars, how many of those people are actually going to modify the car?

When I put the 185 on my car, I was a customer of LET. There are hundreds other customers that have put a few years on the pulley(s) and countless miles. It wasn’t until a year later after my purchase that Eurocharged came to be. I would love to see a customer with 100k on the pulley! But the reality is that may never happen.

Personally, I bolted up 147whp to the car and it was my daily driver for a few years. Did I have some problems with her, sure. But nothing serious that isn’t causing issues with these cars anyway. As everyone says, they are maintenance hogs.

And yes, there are other people like Andy (Eurocharged C32) that has a bigger pulley then the 185 by a lot and has everything that you can do to the car done, and it’s his daily driver as well. I have yet to see a supercharger failure outside of the guy who was running a 192. (anything over 185 needs to have the waterpump modified btw)

And yes, modern engines are supposed to last a while. But, like you hinted at, if you want that longevity she is best to stay stock. Just like anything else, it’s only going to last long if it is properly maintained.

c32AMG-DTM

OP - first things first, welcome.

Your post is well-reasoned and cogent. Two observations that may be of assistance:

1. Your comment about crank-pulley sizes is interesting, but I'm afraid it's the proverbial "catch-22" situation. 178mm aftermarket/tuner crank pullies have been around for around 8 years, from many, many different tuning providers. So, you can get a handle on longevity risks, since they've been around that long. 181's and 185's have only been sold for a couple years - it's impossible to know what their 5, 7, and/or 10+ year longevity impact will be. Might be nothing; might be inconsequential; might be significant. Customers will inevitably request products that push the boundaries of conventional wisdom to unlock newfound power - reputable shops/tuners will oblige if they feel it's prudent to do so. I'd often wondered why the pulley sizes were somewhat "weird" - 178mm, 181mm, 185mm. Why "178" or "181"? Tried converting them into inches, which gave me an educated guess as to the answer.

2. As you correctly reason - auto manufacturers have myriad constraints that might limit performance. Fuel econ., emissions, NVH, not upsetting their model-line hierarchy, the list goes on. That said - anything that increases the hp/tq output of the engine potentially brings additional, perhaps unforeseen, issues or compromises to the table. So, in that regard, the intake is really no different than the tune, or the pulley. The intake's only advantages to the mod-hungry enthusiast is simplicity and ease of install/removal. Oh, and perhaps cost.

Best of luck with your new wheels - and again, welcome.

mjgroves

Many thanks to those of you who took the time to respond, and thanks again for the warm welcome. There were many good points made and I feel that most of my questions were answered. A few comments though:

loungin, I did not realize that such a small difference in pulley size made a huge difference in boost levels. It makes much more sense to me now why they're so close together in terms of size. But I'm still trying to wrap my brain around why LET doesn't just make a SC pulley that matches performance of the 178mm crank. For those who want additional power beyond the SC pulley limitations, the 181 and 185 crank pulleys are available. To summarize, why 178/181/185 crank and not 65mm (?) SC, 181/185 crank. It seems that the people going the more conservative 178 pulley are more concerned with "more power, but the least amount of risk", and that market would be best served by a smaller SC rather than a crank. Perhaps an even better question would be why doesn't LET offer a kit which returns the remaining pulleys to stock speeds?

I actually recently purchased a ECU tune as well as the smallest crank pulley LET offers. Since I was worried about longevity I decided not to go with the larger cranks. I'm having second thoughts about whether I want to go the SC pulley route instead, but I suppose that's something I'll have to decide on in the near future.

There were really two sides to my crank pulley question... how reliable are the internals of the engine, and how reliable are the superchargers. It sounds like both are solid pieces of machinery, but from what I can tell the internals can withstand much more than the peak capability of the supercharger, even at max RPM (am I on the right track here?). So, the supercharger would be the weakest link in this scenario.

Overall, it appears these vehicles are quite reliable even with all these extra modifications (185mm pulley, ecu tune, intake, etc). I was just trying to feel the waters on any potential issues I could run into running a 178mm pulley/tune/intake combo. Hopefully none for many many many miles down the road. And I take great care of my vehicles.

EDIT: Also, I did have one more lingering question. I remember reading a post that stated that even with the 178mm pulley you dont actually overdrive the accessories, power steering, etc until you hit a certain rpm range (around 5000 rpm and higher). I'm still new to this sort of thing, and I'm curious if there's any truth to this statement. Because I would feel a hell of a lot better knowing that my accessories would be running in the stock range during normal driving and not stressed for more than a second or so during "spirited" driving.

EDIT AGAIN: I'm still not certain what it means exactly to "overdrive" accessories. Are we talking different scenarios depending on the accessory (i.e overdriving water pump makes water flow faster, whereas overdriving power steering does ?).

c32AMG-DTM

Well, like most questions, it really depends on how you define "overdrive."

If you mean "overdrive" as in "spin accessory rpms beyond the AMG-designed and spec'd operating range" - then yes, you are only "overdriving" once you exceed x,xxx rpm... it varies, depending on how much larger (%) the aftermarket crank-pulley is vs. stock.

If you mean "overdrive" as in "spin faster than the stock configuration, at any specific engine rpm" - then you're "overdriving" all belt-operated accessories, from the moment you start the engine 'til you shut it off. Supercharger, alternator, water pump, et al. IMHO, this is the usual definition of "overdrive" and "underdrive" as it applies to accessories and pullies.

320 dreamer

welcome. as a member here and on the xfire and on the slkworld and a member on benzworld i search everywere for power. the most? not even close. but the best pwoer for the dollar and mods i choose.
c3 pulley and 178 are very close. 181 and 185 are a different world. stackem and go into the 4th dimension!
the reason people like the 178 is the power down low and others like the 185 for the power in the 1/4 mile. what are your plans for the car? autocross? drag strip? street racing? or a combination. these all come into play. for reliability it comes down to the tuning and fueling. 185 and 181 run lean at the top and the search continues for the fix.
tunes for the 178 and c3 are bullitproof and well documented.
if you choose a 181 or 185 and want the acc run slower the needswings pulley saver kit is the answer. bigger belt and pulleys slow them down. i now have a psk for the c3 on my 32
try the cicci club for membership if you want but i suggest keep trying the srt-6 site. its worth the effort and the info alone is worth the price of admission!
feel free to pm me with any questions.

just as an example with a modded intake c3 s/c pulley and full custom tune and a few minor tweaks i have 341 rwhp and 337 ft/lbs torque. no reliabilty issues. car purrs around town and gets 26 mpg on the hiway.

W203Ramos

welcome to the forum!!!

dlwiser

hi there

loungn14

We actually looked at the sc pulley to produce. At present time, it wasn’t worth the extra R/D, tooling, and field testing to produce something that will have a limited sell with such a limited amount of cars. To produce a different sized pulley was quite easy when you already have the drawings and data to do so.

We looked at that, but in the long run there just hasn’t been any data to prove that adverse effects to warrant production. The alternator pulley is a $%^ to remove as well. With our kits we do replace the idler pulley to makeup some of the difference. And as you said below, the small range of when the accessories are spinning over 5k doesn’t merit such a need.

You made a good decision with the 178. That sized pulley has been on the market for many years and is well documented. That way when you get bored, you can stack the smaller sc pulley on top and retune to get even more power.


I ran one of the highest HP 32’s with no issues whatsoever with the internals of the engine. The engine and components are rock solid and very reliable. I even ran spray sometimes.


You will be fine with the 178/tune/intake. Most people are running that combo or more.


That’s pretty much what we had found as well, above 5k was when it was getting into the higher RPM range.

mjgroves

Well, I'd love to be able to ask more questions, but honestly everyone pretty much covered the remainder of the things I was wondering about (and more). Kudos and thanks again for the input!

positronicC32

Despite being a year old thread, it certainly helped my present day issue. Needed a solution and the 178/tune/intake is it.

Thanks for the great advice

AMG3.2

I know it helped me too! I'm still not too clear though the difference between the 178 and 181 pulley.

mjgroves

I'm glad this thread was useful to others! Just an update: i ended up going with dual intake, code 3 pulley, and eurocharged tune. Seemed like the best combo to me in the end. Went with code 3 because it was cheaper, easier to install, and was the "safest" option in terms of boost levels (178 is comparable). I have also recently purchased modified intake manifolds for extra airflow.

AMG, If i wanted more power the only other option i would choose is the 181 pulley, which is about 10-15 more hp/tq due to higher boost levels. The C3 was a better option in my eyes since i am concerned with longevity. Physically theres little difference between the 178 and 181 crank pulleys.

AMG3.2

Very good to here! How much additional power are you making with the 178? Also if you don't mind me asking, how much was the pulley and tune?

positronicC32

Thanks for the update A 'safe' level of boost is my aim too. My fear is that I'll overdrive it with a bigger pulley and accessories will start to fail.

Just had the #4 pulley totally seize - which slipped the belt - and I'm having the SC bearing replaced as it's rattling.

I've decided after much research to go for a 178mm pulley setup. Do I need to get a tune for that upgrade?

I will get a performance intake installed at the same time. No HE at this stage (as it's currently Winter here).

This is my daily drive so rarely use full power.

AMG3.2

I'm in the exact same situation!

positronicC32

Oh dear. The slipped belt caused damage to the water pump. And I'm told I need a new SC Pulley...figured that already with the chirping / rattling that's steadily been emanating from it. At least the actual SC and Coupler are OK.

So, where do I get a stock SC Pulley from? The Stealership want $4,400 for the SC coupling...but it's the actual SC Pulley that's almost fried. Here's the price list MB sent me today.

Here is the parts list
1.belt tightener pulley $183.78
2.coupling $4301.56 (actually require the SC pulley in front of the SC Clutch)

3.ts water pump $749.88 (CARDONE Select Water Pump from RockAuto is a suitable replacement @ $162.79)
4.tightener pulley $204.61
5.antifreeze $94.65


I asked about the cost of a new SC...$8,470 + install (4 hours) $770 = $9,240. Usher was right! OMG

gt4awd

Ouch, can get the full clutch here in the states for around $1400...

Newzchspy

+1, I've said this many times that I "prefer" the SC pulley, BUT to each his own. There's a LOT of strong running 181 and 185s out there, so who am I to argue?? I've got 20 K miles on my SC pullied C32 and haven't had to replace a bearing yet. BUT, that's just me. Is it as strong as a 185 crank pulley, probably not. But there's trade-offs to everything.

positronicC32

If you can point me in the right direction I'd certainly appreciate it! Options here in Oz are limited.

320 dreamer

oediscountparts.com