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Discussion Starter #1
Here's my latest/last 1 off CAI piping to outside grill goes to nearly 5" DIA.. It's far and away best CAI I've come up w/ALL silicone tubing w/gradual decrease to puny stock turbo air inlets. Wrapped in graphite header wrap, except for last 5-6" exiting front grill.. Wheels are new lightweight CCW's 18x13 wrapped in NEW Toyo R888 335/30 breaks loose in all 5 gears 57 deg F tnite ;) MB tech chkd boost in Star Diag laptop again, while I drove hit 26-27 psi.. External BOV's sound insane, like fast spooling high pitched exotic


"DUAL ELEPHANT TRUNK" V12 BITURBO CAI
 

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breaks loose in 1st-5th gear? Im interested in hearing more about specs of car. Also, 26psi.. What is the stock psi on these cars?
 

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You should be more concerned with bank to bank variation in AFR than boost pressure. Curious to see the margin when either of these start collapsing under vacuum.
 

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To expand on that, here is what I see- I'm not aware of how exactly MBZ manages their fuel trims, but it would occur to me that if under vacuum one of those does collapse, that particular bank is going to see the following: Choked air supply under heavy load (read: boost), AFR goes rich, O2's pick this up and compensate by dialing back fuel to keep stoich. As soon the car hits a shift point, boost drops, pressure bleeds off through the wastegates, and the collapsed tube regains form... all in a split second. Immediately, you're back in full boost in the next gear, and all of a sudden extremely lean in that bank as you've just reintroduced 27psi while the ecu is still only feeding fuel based on the short term trims sampled during that bank's rich condition.

Basically, in an instant, you'd go from say 12.5:1, down to a pig rich 7 or 8:1, then spike back up to 15 or 16:1.... which can and will detonate and kill a motor in a split second.

This isn't a guarantee, but its a legitimate risk that all makes mechanical sense in my head. I'm completely open to discussing that further if anybody knows more about Benz's ECU's.
 

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Discussion Starter #10
M275 biturbo engines don't run peak boost full time, mines heavily modified. It hits 26-27 lbs for a couple sec @ 4500 rpm's then boost falls to high teens thru the remainder of band.. AFR's safe @ 12.3 only runs supreme or race fuel. Makes 633 whp 750 wtq on 91 CA pump.. Been safely running like this for 3+ years...
 

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Discussion Starter #12
stock is 13 for 600 m275 18 for 65 m275
 

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not sure whether your car is the 600 or the 65 but sl65's with the m275 come stock with 22.1psi rated from the factory. where are you getting 13 and 18?
 

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Discussion Starter #14 (Edited)
mines a 600, stk boost is 13.. You're incorrect, I know these 275's inside n' out stock boost on 65 is indeed 18... after ECU tuning both 600/65 top out at 21-22 psi
they both share m275 platform, the 600 is a scant smaller at 5.5 liters, the 65 is 6.0 liters, w/slightly bigger impeller wheels in turbo.. after both equally modded they make nearly same rwhp, w/slight bump in rwtq to 65.. the .05 larger liter in displacement is purely bragging rights. The turbo sizing & larger fuel inj etc etc make up the dif between the 2..
 

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any source for this? wikipedia, caranddriver, and mbworld ALL say 22 for the 65... Not saying I know the numbers from personal experience but I find it hard to believe all 3 of those sites are wrong.
 

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Discussion Starter #17 (Edited)
I'm good friends w/ Marcin, at Speedriven owner, resident v12 tt guru..Call him, everything I know he's taught me on these V12's... I'm lost lol ;) Take my word or not peace.. My acct here is linked to my FB acct where I've posted umpteen details on speedrivens FB page... Marcin also knows my SL innately... also posted all details on MBW etc etc.. just wanted to share new CAI w/fellow v12 enthusiasts..
 

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simple mod list would have sufficed but it's all good. I don't know speedriven's full catalog and couldn't find anything other than the posts about your home made CAI on there.
 
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