I get a lot of questions about what the best intake is, how big should I go for the TB, or how can I get such and such power. I will be putting together these write ups for all aspects of modding the engine. I will be quoting only OEM MB part numbers as there are a lot of interchangable parts available.

I will start with Induction and move onto fueling and exhaust. These are the three most moddable areas and the ones where the most HP can be gained with the least amount of money.

As I research more OEM parts I will update the write ups.

Enjoy!

INDUCTION

The Crossfire was plagued from the very beginning by poor induction. A small Airbox with 2.5” intake tubes was the best Chrysler could get away with as to not step on the MB owners’ toes. Once air is ingested through those “straws” it must squeeze its way through a 2.5” MAF, with 2 screens mind you, past a nice 3” elbow, unfortunately with some obstructive fins, and then finally through a 68mm TB, about 2.5”.

The stock system is limited by its smallest opening, in this instance it is 2.5”. Our goal is to open the intake up to 3” all the way through to allow more air and thus more HP potential. The following are a list of OEM MB parts that are bolt on and will result in a 3” overall size for the intake parts.

• C240/C320 Airbox: PN: A1120901501; this increases overall filter area by approximately 50%, Airbox volume by 35%, and increases intake tubes to 3”, a 20% increase from stock

• M113 MAF: PN: A1130940048; The V8 MAF is a full 3” design that allows for increased flow. Not only is it just a larger housing, but the MAF is tuned to run at the larger volume and thus will compensate correctly for the additional airflow. There are inherent issues with putting a non-collaborated MAF in a larger volume, this eliminates that.

• M113 Throttle Body: PN: A1131410125; The larger V8 TB is opened up to 74 mm and matches the inlet of the intake manifold perfectly. The engine will need to adjust to the new TB when first installed and a learning period of about 3-5 mins is necessary. Simply turn the key to the second position and let the TB calibrate itself.

 

Thanks for the effort. This will answer so many questions.

 

great post - Thanks

 

Ok, where do I buy? I'm ready.

 

Great post! Looking forward to the updates.

 

Shoot me a PM and let me know waht you are looking for and I'll give you our dealer price.

 

FUELING

The stock M112 motor in the Crossfire is aimed at being a jack of all trades, master of none type of engine. It went in everything from a sports car to a SUV. To keep emissions at a minimum MB decided to keep the car at a fairly lean AFR. The stock injectors are a paltry 15 lbs/hr and on a bone stock motor are running at 80% duty cycle at WOT. This limits HP potential, but also makes for a good compromise of low end torque, low emissions, and decent MPG. Once you start ingesting more air into the engine the stock injectors quickly become inadequate.

Our goal is to increase the amount of fuel able to be added to the mix, thus allowing us a larger window for timing advance. More fuel + More Air + More Timing = More Power!

• 430/500 M113 Fuel Injectors: PN: A1130780249; These injectors are rated at 19 lbs/hr and are a great upgrade for a bolt on car. When coupled with the above bolt on intake mods and an aggressive tune, you can see anywhere from 260-275 HP at the crank. All the while maintaining OEM reliability, very good MPG, and low emissions.

• C43/C55 M113 Fuel Injectors: PN: A1130780023; These monsters flow 21 lbs/hr and are perfect for a highly modified crossfire running headers, larger exhaust, cams, and head work. These injectors will support upwards of 375 HP.

 

Have you found the power limit of either maf? or the stock fuel pump?

 

Sticky! Sticky! Sticky! Sticky! Sticky! Sticky!

 

It appears that the stock maf will be good until about 275ish HP and the larger unit over 400 HP. This is NA power so adding boost to this will change the results substantially.

 

how do you get 375hp from a 21lb injector? my calulations say you need a 39lb inj on an n/a using .50 bsfc

 

Same way you can get away with 215 HP with a 15 lbs/hr injector. Calculators are good starting points, but don't tell the whole picture.

Idealy I would run a 30 lbs/hr injector for anything over 350 HP, but that isn't going to be much of an issue on these NA motors.

The HP numbers that I quoted were for a v8, sorry about that. A 21 lbs injector would be good to about 325ish.

 

Wow thank you so much for these posts. I used to think the N/A didn't have much available to get more power, but apparantly you can do it with even MB parts.

I'm curious. With the injectors, maf, airbox, and TB, what area of price are we looking at? Not looking for specific cost, but are we looking at something like $300, or something up at $1,000 or more?

 

If you do all brand new OEM parts you are looking at over 1.3K. This list is meant to offer you parts to find used or new and compare to some of the aftermarket offerings.

The injectors are roughly 525.00 from the dealer, we offer a better injector (newer design) for 450.00. If you can find them used, its a good deal though.

The MAF is 225.00ish new, but I'm sure there are tons of used ones in scrap yards for under 100.00.

 

FUEL SYSTEM

CLK430 Fuel Pump: PN: A0004707894; The stock fuel pump is more the adequate at 160 l/hr to support up to 390 Crank HP (N/A), but for those of us that like to push the envelope and have added a little boost or nitrous, then a new pump is in order. The M113 (CLK430 used as example) pump flows a healthy 205 l/hr and will support upwards of 500 HP N/A or 380 HP FI.

 

im assuming the maf's use the same plug?

also, with the na fuel system. does the pump supply a constant 58psi, or does the ecu modulate voltage to raise the fuel pressure?

I have a spare walbro 255 laying around as i was thinking of mounting it in place of the stock pump

 

A piece of advice to all. Have your car dyno'd stock before doing any mods. This will give you a base line to compare your gains in performance with each mod. Use the same dyno as they do vary in reporting.

I'm not sure there is any performance gains by replacing the injectors. If anyone wants a set of the 29# injectors from Anthony, I will sell you mine for 1/2 the price, but will need your stock injectors in trade.

 

I would hope anyone would think to do that.
I have many shops that owe me dyno runs, so I plan to finally collect.

The injectors wouldn't really do much on a stock motor, but since they are at 80% flow on a stock motor (85 is the limit, as some lockup) but once you start doing things like, exhaust, intake, porting, etc, etc

The injectors start to shine

 

I Absolutely agree with FP here

 

You guys are making my right foot stiff with all this talk of improving my roadster


...only thing outside of setting aside "mad money" to do this is the fact I'm afraid I would violate my warranty.



edit: sorry ladies, some things a man just can't lie about