from old school to new - PeachParts Mercedes-Benz Forum

oldsinner111 · #1 07-22-2011, 08:16 AM

Hey all:I'm from the 70s era.We take engines and add larger carbs to boost horsepower.Some were called 750 cfm double pumper holleys.Even small 4 bangers would benifit from larger carbs and headers.
Now my question,with these fuel injected engines. Can you add headers,larger injectors,and larger throttle bodies to get power?The injectors,and throttle plate acting as a larger carb?

RBYCC · #2 07-22-2011, 10:04 AM

I'm from the 60's and back then you were able to put your distributor in a Sun machine and recurve it to match your fuel supply.

Problem now is the engine management will output to the fuel and ignition systems only what it's programmed to do.

You have to modify engine management to take advantage of additional fuel.

Ed A.

400Eric · #3 07-22-2011, 10:23 AM

I'm old school 70s era cars myself. (Check my sig.) I started embracing this funky FI stuff only about 5 years ago mostly out of necessity because the old stuff is getting to be too impractical for daily use anymore.

Modding these FI cars gets rather complicated. I've had it fairly easy cause my W124s are from an era where the ECUs were generous with the W.O.T. fuel enrichment. Well my 93 and 95 weren't but I fixed that with a swap to 92 ECUs in both of them. With your car that is not an option. (HFM never had WOT fuel enrichment.) Anything you do might adversely affect fuel economy so be careful. Member Jay Rash will have to be the one to help you here because I think he is the one with the most experience hopping up a HFM equipped Benz around here. PM him and tell him to please weigh in on this thread so that all can benefit from the knowledge. His HFM car came stock with a AMG tweaked ECU that was/is more generous with the WOT fuel than any other HFM ECUs were/are though so even he had some help there.
Regards, Eric

oldsinner111 · #4 07-22-2011, 10:33 AM

Ok then the air,and hopped up injectors,only work with a ECU that can raise sprark and timing.Maybe tear down engine find a distrubter,and a Holley 4bl carb.Thanks guys.

JayRash · #5 07-22-2011, 10:45 AM

Im here Eric, well im not really any more expert on HFM than the next guy, but thanx for the pep talk. Any way my tricks are make shift options that hit one spot but miss on another. Btw my AMG doesnt run any richer than any HFM M104. My AMG on WOT runs at 12.8 AFR flat.

As for the OP well you can do a trick that will advance the timing to give u a few more hp. also u can do same trick for fuel thou i really doubt fuel will give u any hp. if this is what ur after just let me know to start spilling the details.

oldsinner111 · #6 07-22-2011, 10:52 AM

I'm all ears.

oldsinner111 · #7 07-22-2011, 11:05 AM

Things I did so far. Deleted Cats,and first muffler,Modified grille and airbox.Grille removed triangles from top corners on inside of grill..Airbox wrapped with Cool It Tape,and modified air opening to 4' diameter,using drain hose to grille.
Also wrapped headers, an crossover.GForce resistor.170f thermostat

JayRash · #8 07-22-2011, 11:29 AM

Quote:

Originally Posted by oldsinner111

I'm all ears.

The trick is to fool the ECU into reading a lower water temp. I have posted a few pics to which wire u need to cut and add a resistor to, I suggest u add a variable resistance and make sure u can unplug it so that u can properly measure the resistance u dial in. the thing is you will need to try out a few times with higher OHM values until u start hearing knock and then pull back a little. Start with abt 400Ohms .
On my AMG I can’t go over 400 or I get knock on the 3.2 I guess ull be safe with 400 since the ecu is less aggressive.
oh the temp sensor is the one on the water thermostat housing. it has 4 wires. the one that sends signal to the timing is the one i cut. for the fuel it is the one to its left. but take my word fuel will not give u any HP. and if u use fuel with ethanol in it u should be able to run higher values giving u more timing advance.

JayRash · #9 07-22-2011, 11:43 AM

Quote:

Originally Posted by oldsinner111

Things I did so far. Deleted Cats,and first muffler,Modified grille and airbox.Grille removed triangles from top corners on inside of grill..Airbox wrapped with Cool It Tape,and modified air opening to 4' diameter,using drain hose to grille.
Also wrapped headers, an crossover.GForce resistor.170f thermostat

That looks good to me

On My AMG i have done almost same things.

oldsinner111 · #10 07-22-2011, 11:46 AM

Hey Jay I'm shooting for Amg 3.6 performance.I will add Nitrous next year I think or water/meth injection.I have 2 boys and have to build power cheaply.

JayRash · #11 07-22-2011, 11:54 AM

go with nitro water / meth will not help u much.

oldsinner111 · #12 07-22-2011, 12:30 PM

are you saying the variable resistor fits between timing wire and fuel wire. Or timing wire and sender?Where to find a resistor?.The ones I see have 3 leads.

JayRash · #13 07-22-2011, 12:47 PM

The wire in the pic u see cut is the hot wire that takes the reading for the timing. U cut that one and reconnect with a resistance in the middle. Yes almost all variable ones have three leads on them. U need an ohm meter to know which one gives a constant max value and which one is the variable. I hope the pics are clear enough on how I made it. I'll try and post some other pics as well.

oldsinner111 · #14 07-22-2011, 12:49 PM

Thank Jay.Your mountain drive on youtube is scary.

JayRash · #15 07-22-2011, 01:10 PM

Quote:

Originally Posted by oldsinner111

Thank Jay.Your mountain drive on youtube is scary.

The way i did is i cut the wire then used some regular 12v power leads so that i can put the variable resistor near the fuse box. i also used a male/female telphone plugs so that i can easily plug and un plug the variable resistor. if u need to return to stock just place a wire in the plug shorting the resistor and car will run as stock. u need to switch car off then on for any change to take effect.

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