I agree with this post. Mr. Sulayem's set up provides boost down low from the SC'er and then once the turbo(s) spooled, it bypassed and turned off the supercharger. Afterall, there is still a limit to how much boost the engine can tollerate. Still, a properly sized turbo system will spool quickly and make adequate boost without all of the extra weight and complexity of keeping the SC'er in place. The greatest gain to be had is not from adding more boost so much as from ellimination of all of the parasitic losses from the supercharger. That is where the big gains are to be had.

The engine will make more power with added boost up to the point that something breaks. The fuel delivery system on the AMG engine is one bottle neck. To go much above 22 psi will take some significant modifications to the ECU system and fuel rail/injectors. Nobody, I know has solved that challenge with this engine due to the digital control of everything thru the ECU making a stand alone very hard to do. The engine is strong and could likely tollerate much more but without a control system, it would not function.

Irish

 

I'm sure there is a lot of power to be gained by switching to a turbo, but I think there would be a few headaches as well. The major one being HEAT

The SRT6 is the first NON-Turbo car I've owned the previous cars being:

1986 & 1985 1/2 Svo Mustang (2)

1987, 1988, 1989 Chrysler Conquest Tsi

1992 Toyota Supra Turbo

and each of those cars were affected by the extra heat a Turbo adds. Hoses become hard and brittle and every car except the SVOs suffered from blowing head gaskets - you DON'T go accelerating under higher boost levels in 90+ degree weather or you are ASKING FOR TROUBLE.


So unless it is for track purposes a turbo is just not worth all the hassles. Like others have suggested I think a more effective or bigger blower would be the better route.


If we have an occasional now - there will be many more with a turbo - just look at the headaches in fitting/tuning one to the car.

I'm sure there is massive power to be made with a Turbo and am eager to see what they can do and then will be envious, but I'm happy to have replaced my last Turbo cars with a Supercharged one... I still do own a Turbo Pt Cruiser.




I'm sure the development of the Turbo system will be exciting to keep tabs on and wouldn't doubt if 600 horsepower or more was achieved. I'd really love to see how much these engines can put out before they reach their breaking point. Hell I think sometimes much over 300 might be too much for the street - at least for me.

 

I guess nobody had fully comprehended what I was attempting to say. That's my bad. Please allow me to try again. The same engine with a supercharger or a turbo will always make more power at the "Same" level of boost when running the turbo option, because the turbo does not use any of the crank horsepower to drive the compressor.

True, you can make more boost and additional power by either spinning the existing compressor faster or installing a larger compressor. Eitherway, you use up a significant amount of horsepower just to spin the screws in the supercharger. That is never the case with the turbocharger since it is driven off the hot exhaust gases. It is very true that turbos concentrate heat in the engine bay and that must be dealt with. But heat is potential horsepower and if you can put it into the engine, you can capture at least some of it at the wheels.

Another somewhat unrelated observation that I have made is that in hotter ambient temperatures, a turbo car is affected less than a supercharged or N/A car. When the air is hot, less dense and the oxygen molecules per cubic foot are lower, most N/A or supercharged engines make less power. That is because no matter what else you do, less air is being forced into the cylinders under hot ambient conditions. In the case of a turbo, they are also affected but since they are controled not by the speed of the crank but by the exhaust and the wastegate, the only major difference that I have seen is that it takes more RPM's to reach full boost and to a lesser degree, it sometimes will make less boost for the same conditions unless the boost controller is adjusted. The same thing takes place if you drive to a higher altitude. The turbo suffers less power loss. That is why when adjusting for Density Altitude, the turbo cars get less compensation.

If you track the absolute pressure on the intake tract of a supercharged car, it will always make less boost at hot temps because it is spinning at the same rate regardless of outside temps and there is no practical way to adjust that. On the other hand turbos have a sort of self adjusting system so they can partially compensate for this within a certain range of operating conditions. I have an old turbo bike that runs about 17 psi boost. At sea level it takes 4000 rpm to make full boost. The same bike at 6000 ft elevation takes ~6000 rpm to reach full boost. Once up to full boost it runs just like it did at sea level, while its N/A counterparts are sucking wind. At some elevation height, it would no longer be able to spin the compressor fast enough to make full boost, but at least where I live, that is not an issue.

Irish

 

typically the turbo will have a narrow powerband compared to the wide powerband of the supercharger. I have seen it countless times at the track, a wide powerband beats a narrow peaky powerband even if the peaky turbo powerband has a higher peak whp than the car wtih a wide powerband.

There are some cases where the turbo is matched well with the motor and the powerband is pretty good but a lot of the time you do not have that nice wide powerband that makes your car fast, not just roll racing fast.

Can you guys post up your dyno graph so we can see it, I do not understand why it has not been posted yet.

 

It was posted on page one.



I know the printer was down for a while... not sure if it is back up and running yet.

 

The dyno chart I posted is VERY hard to read, but if the top line is horsepower and the bottom line is torque, then it looks like the turbo is hitting choke. The torque falls flat once the airflow limit of the compressor is reached. On something like a GT4294 with 1000cc injectors, the car should be able to make some fairly serious power.

 

All, I can say to that comment is: "Go out and drive some more turbo cars" cause the ones that you have been playing with must have been really poorly set up. True that a flat broad torque curve will often beat a narrow peaky one at the track. But every turbo that I have owned or had any seat time in had a very broad torque curve. Porsche turbo had serious power from 3500 rpm to redline at 6500. My MR2 had serious power from 2500 rpm to redline at 7000. That is a useful powerband of 4500 rpm. It surely is not "Peaky". My Mazda turbo made serious power and full boost from 3k up to 7k. My Honda turbo makes power and full boost from 4k up to 9k rpm. It pulls as hard at 5k in 5th gear as it does at 9k in 3rd gear. The "only place" the supercharged engine has a real advantage is from off idle up to whatever point the turbo is making full boost. Usually that is a narrow range. From that point on, the turbo makes more torque and more hp for the same level of boost and stress on the engine. The supercharger will have a small advantage in an autocross type situation or in a very technical tight road course where the off boost to on power transitions are numerous but if the track has any place where the full output can be applied, then the turbo car will reel in the others fast.

Irish

 

i remember that but it is too hard to read. thanks for the info though.

 

Talk to Kansus, bet he can install an srt6 ecu in your NA car..

 

Wow..400+ SRT6! Is that just with a single turbo mod? I assume you replace the sc completely with the turbo. Is it possible to do it on a regular crossfire? Keep up the good work

 

Single turbo

No SC

N/A application is not in the works just yet as the internal improvements that would be necessary and the pricing would be really expensive.

 

that avatar........

 

she's a lot of fun and doesn't talk back...

...and when i'm done with her I can return her from where she came from and get $30 bucks and can buy another one...thats a win win situation.

...it will change soon, i'm sure.

 

So what's this car like to drive? How's it treating you? etc etc...

 

Yup, quoting myself.

So no input on this ImportLab?

 

I know last week was pretty hectic for Bryan and I and a few other volunteers helping Eurocharged to get ready for HIN Chicago... I'd give him a few days to recover and get back on here regularly.

 

As Matt posted, I have spent the past couple weeks getting the car looking a little better for Hot Import Nights. Added my new wheels, some window tint and Koni Shocks with Eibach springs.

Now for the turbo news.....I daily drive this car and have yet to have any problems other than a little overheating issue. 2 weeks ago there was a few days where the outside temp was over 100deg and where my FMIC is located, it was blocking most of the air going to the radiator. Nascar style, I pulled the front lower grills and the temps went back down to normal.
I now have 2k miles on this setup and love it. City I get about 22mpg and highway I get 28mpg with A/C on and 31mpg w/o A/C. I have yet to up the boost and play with the tune. The car is on the rich side for safety so more power is there even at 15-16psi that I am at now. When its cold out at night, I see 18+ psi at times and the car hauls ***.....bbbbuuuuttt if the car sees 20psi, the ECU gets a little pissed off and cuts fuel + spark.
As for track use, a torque converter is going to be needed to get the car off the line. I can only get 11-1200 rpms out of my stock converter at the line before I push the front wheels thru the beam. At 1100rpms, the turbo only builds about 1lb of boost and when I let off the brake the car bogs and slowly crawls to a 2.6 60ft and blows my Hoosiers away going into 2nd and at times 3rd. My next goal is to get 20-21psi out of this thing. Fuel injectors and a fuel pump will have to be sourced

 

Its times like this I wished I lived over the pond!!! You get all the best toys!

 

Thanks for posting the driver impressions. You do a great job of describing the way the car has changed. A electronic trans-brake or a brake placed on the driveshaft could solve your launch issues. Hit the button to apply the brake, gas it up to build some boost and when the tree falls or the light turns green. release the button and go. But if it is blowing away the tires in 2nd or even 3rd now, lol then gawd help you in first if it is up to even moderate boost. Bigger rears tires and really great rubber (maybe even DR's) would be required to really get the most out of it. I am very impressed to see how much the fuel mileage has improved. I never dreamed that the SC'er was placing that much drag on the engine when cruising.

Now for the Fuel Cut issue. Find the pressure sensor module the reads analog pressure and converts it to a voltage. That voltage input will be routed to the ECU and when it reaches a set value will trigger fuel cut which is supposed to be at a preset inlet pressure. In your case you reported 20-21 psi. You can put a voltmeter on the output voltage and use a pressurized outside source to apply adjustable pressure to the module until it reads 20psi. Note: take a 6 in piece of 3" PVC pipe, glue two end caps on it and place a tire valve stem in it and a small nipple with a rubber hose to the module. Install a pressure valve or use the one on your compressor/pump to pressurize this resouvoir and the module in a controlled manner. Do this slowly and take care to not apply extreme pressure to the module to avoid damage.

Read the voltage and you now know how high it must be to trigger fuel cut at the ECU. Many common automotive pressure modules will read 5 vdc but that can only be determined by manipulating the module to see what it does. Once you know this, you can fairly easily adjust this to reach the desired fuel cut. Some people even defeat the entire FC system but that is very risky on a expensive engine.

For a different turbo car project I built an adjustable voltage splitter circuit that takes the input voltage from the sensor and reduces it by using a fixed resistor and a adjustable resistor. It is a simple, adjustable, reliable device that can be spliced into the harness and arbitrarilly reduces the voltage seen by the ECU. Then with some trial and error, this will enable you to manually increase the level of boost that triggers the fuel cut to a higher value. WARNING - this can lead to engine damage if you increase boost to a level that either maxes out the injectors/fuel rail/fuel pump whichever turns out to be the bottleneck and/or causes detonation. It is guesswork to edge this up and somewhat unknown territory. With our engines the knock sensors will start pulling timing advance if detonation occurs but going too lean is bad news. You really need to install a wide-band O2 sensor in the turbo downpipe to monitor that cause it is gonna drift with atomospheric conditions every day. Normally the ECU will compensate but when you push the systems to their max fuel flow rates, they can no longer adjust. Simply putting in bigger injectors is not enough unless you also can reprogram the ECU. If you get that done, I want to hear about it as it has been a constant problem on the C-Klasse MB forum.

In my case I set my FCD to 18psi but my injectors max out at 16-17 psi. I use the boost controller as my first line of defense and the FCD as my 2nd. The final line of control and protection is the knock sensors. My car is set very rich also for safety. If I wanted to lean it out by a percent or two, I could safely run up to 18 psi on that system (it was set to 12 psi from the factory). Yours is different and the limits will also be different but there is usually a small safety factor that can be stolen albeit with added risk. At some pressure limit you will begin to over stress mechanical components such as rods, and head studs/bolts. It is a big guessing game to go there, lol -- You usually find those when you detonate at full boost unexpectedly and the pressures in the cylinder go up exponentially... have fun! You are breaking new ground. I am very impressed with it.

Irish

 

That's awesome that the mileage increased like that.

Do the guys running the 185 pulley have the same issue? Perhaps a MAP clamp is in order—as long as your AFR is covered (which sounds like it is due to your rich comment).

That sounds like the difficult part of the conversion. Like others have said a 2-Step rev limiter would/should solve the problem but wiring it into the ECU sounds a bit daunting (at least to me ).

Thanks for the updated facts on living with this build especially as a daily driver. Kudos!