Headers are the hold back. I think that exhaust is probably only going to show minimal gains headers done right would be a difference maker, the engine bay is very tight though. Would require a good header/welder to create some.

 

Bingo.

I completely agree

 

I'm just as stumped as you then. N/A Crossfires have the same exact manifolds, shrouding the exhaust port and all, and yet we can't see any gains. A big WTF there!

 

A member spent a whole weekend swapping out his stock manifolds for headers. Before and after dynos. Lets just say the stockers went back on.

 

The only headers shown have been poor quality makeshift ones with sloppy welds. If there's a good set out there on a running car pictures would be nice. I don't think a "good" set has been made to truly test the gains here. I'm sure the stock manifolds could see an upgrade though stock is never optimal.

 

I think it had to do with the overall design. E55s are gaining with headers but they have the room for a traditional set of mid or even long tubes. I personally think they are going too large with the primaries as one of the issues.

 

could it possibly be the size of the throttle body as well as the headers? the VRP headers looked pretty darn good, but turned out to be a horrible fiasco for 240M3SRT. he even LOST torque. perhaps it needed another tune, i don't know.

it's just strange, we're making 'V8' power, which typically on V8's, you swap out the exhaust and make good chunks of power! it's just so weird.

 

Yeah, I do think the throttle body is one of the bottlenecks. Given the dual CAI flow that much better on the flowbench, but do not do as much while on the car indicates a restriction. We should start there and work our way through the engine. :P can the SC handle more air in!?

 

Probably a good question for Inmotion if the tune needs to be done to take advantage of the changes or if the ECU would adapt to it over time.

 

my next mods are IPT valve body upgrade and 12lbs racing seats. can't think of much else (besides pulley) to go faster.

i'm surprised we haven't heard if any of the bigger benz throttle-bodies work on our car.....

 

Bigger MBZ throttle bodies might work but they're expensive as hell. If you know someone with an E55 ask them if you can borrow it.

 

The LX throttle bodies are 80 mm if I'm not mistaken. Maybe one could be made to work with a little modification.

Les

 

We need to figure out something......Does anyone think a port and polish of the stock one would add any gains??

 

It's been done to the stock LX throttle bodies and is good for 6 to 8 hp on the 5.7 and a few hp more on the 6.1. This is opening is up as far as the thickness will allow which is up to 85mm. The butterfly area stays the same size. (untouched) Is it worth the trouble? Don't know for sure but someone will eventually find out.

Les

 

The nice thing about the SRT-6 is you guys are in the 11's and you have done nothing internal. Tune a pulley CAI. To a V8 they would make a face if you said I'm running an 11's with bolt ons on a stock motor. No Cams, No port work on the heads, no bigger valves, no headers..... 11's for a street car is really good, even on modified cars Induction or not. So the SRT is a great platform and I think once the heads come off some port work is done (maybe a port match on the exhaust manifolds) greater numbers should be seen and the tuners can tinker more on the dyno. Granted with the machine work will have to go to a Mercedes Machinest who knows there stuff not your local shop down the road that's used to doing fords and chevy's.

 

MDSRT6 just sent off his heads, supercharger, IC, manifolds, TB all off to a shop to have around 3k worth of work done to it all. I am curious to what he is going to find.

I think our restriction is going to be the SC and Computer.

 

just remember sean760 these motors are a very rare motor. when the m/b decided to change the slk32 to the new body stlye and use a v8 instead of the v6 your srt 6 was using the last motors available. now with the split of m/b and chrysler it isnt going to be easy to replace these beautys. as long as you stay with bolt ons i think these motors are bullit proof to a point. when you start messing with the inside shaving parts to get every inch of power i think failure will rear its ugly head and getting a new motor today runs roughly 30,000$!!!!!!
unlike the chevy or fords of today with hundreds of thousands of cases there are maybe a few thousand of these motors? i dont know how many srt6 were built but there are were 2056 slk32 amg shipped to the us

 

For $30K you can buy two of these cars. I bought a complete engine assembly from LKQ for $4k.

 

lkq the parts recycler? im talking about a brand new 3.2 amg supercharged motor from germany. never said it was cheap! but thats the price for 1
although 4k isnt bad for a used motor, you just dont know how it was treated.
my point being these motors arent near as plentyful as most and to tear into the heart to find hp invites disaster
heres a link to show the m/b side of the motor production numbers. sorry forgot to add the c32 so it may be a couple thousand more
http://www.topgearage.com/?p=260#more-260

sorry my bad. the 3.2 doesnt cost 30k. its 46k!!!
http://www.mercedesbenzgenuineparts.com/
just type in slk and the yr go to engine and search slk32. i almost puked!!!

 

I have a dyno date to get the 185 results (gains) this month and after that I will be adding the Different manifolds to see what gains that provides. I plan on pulling the throttle body again to see what can be done there also.

My design of the dual cai was to reduce UPSTREAM restrictions to the throttle body and gained 1 PSIG of boost by dropping the inlet restriction 1 PSIG of friction. My boost is now running in excess of 24 PSIG (measured at the manifold !) and more would seem to be getting risky in my opinion.

Woody