'05 SRT-6
I'm new to computer controlled Superchargers. First time Autocross today. From a dead stop the power is amazing. Hit the brake then need power it feels anemic. By the time the power returns, time to brake again. There were Mini-Coopers on the track and their power is close to instant under all circumstances. What should I expect from the SRT-6 for power delivery and is there a way I can adjust? I unpluged the supercharger clutch to confirm it is working, it is. Unplugged it has less power than my NA Crossfire. Your insight and wisdom is greatly appreciated.

 

I cannot say it is computer controlled, it is driven by a belt mostly all the time. I would say you need to manually select a lower gear, keep the revs up and not rely on the auto shift too much.

 

I'm pretty sure it's more that the transmissions in these cars are somewhat sluggish. My srt6 sucks coming out of corners or from a roll in automatic mode. In manual mode, the car pulls hard as hell all the time once you figure out how each gear works. 1st and 2nd are powerful throughout the entire rpm band. In 3rd, you need to have high rpms to get power out of it. Try to come out of a corner in 2nd if possible and if u have to use 3rd, then you better time your shift so that you have high rpms when the car actually does shift into it.

 

You need to go to needswings.com & eurocharged.com and spend some money....

 

How low are the RPM's when you feel this?

 

I wouldnt blame the supercharger its either on or off due to the clutch, what OP is describing sounds more like the slow drive by wire. If his car is stock, id put a tune on it. In auto only mode and stock the throttle and gas pedal talk to each through molasses. Its a little bit better when in manual but not by much. That delay is horrible. Drive by wire during the 90's when they were being put on cars were horrible. They are much better on today's cars obviously but just like electronic steering assist is working out the bugs to feel more natural like hydraulic assisted steering, drive by wire went through the same thing.

 

My moneys with bbsrt6. I've had the SLK32 (same car...almost) nearly 5 years and when driving hard around any corner, u need 2nd gear going into it under brakes. The SRT6 does 64mph in 2nd at 6200rpm and the engine is still as quiet as a mouse at 3500rpm (36mph). You get used to finessing the +/- shift the more you drive the car. Besides, it will automatically change up to 3rd if you redline it coming out of the corner, but a 60mph corner is very fast and very rare in my world.

PS - the SC only cuts out (clutch disengages) when in Park and if AIT's are high (not sure on the value - maybe >180F(80C) - someone else can confirm). High AIT's can happen more in autocross after continual high rpms and low speed (cornering) which leads to heat soak in the Engine/Supercharger/IC components. The low speed obivously not cooling the engine, the high rpms (>2500rpm) cause higher boost = more SC compression heat into the IC. On the standard heat exchanger/pump, I've found the IC/HX circuit needs at least 30 seconds at >50mph(80kph) to dissipate the added energy of a 5 second WOT event for temperatures to return to where they were before the WOT.
Although this is controlled by the ECU - its not really a high level of computer control.

 

WOW !!! I actually understood ALL of that.
Not usually the case for most of your posts, waaaaay over my head in most cases.
( I don't currently have a SRT6, maybe some day when I grow up )

 

Confesson. It was actually my wife doing Autocross. I'm the mechanic. Medical issue keeps me off the track. You guys bring up a number of great issues. Hard braking into a turn then back on the gas is the issue. She manually sets the car in 1 at start then to 2 and leaves it in 2nd for the remainder of the course. Sometimes it automatically advances. It's about a 45 second run. I have a NA Crossfire. Wife and I will go out so she can duplicate her experiences but my best guess is the RPM runs down to 1200-1800 then spools back up. I'll try a throttle re-learn to see if it helps. Overall, yes spending some $$ at NeedsWings will help but I also think practice with manually changing (bbsrt6) the auto trans to keep the RPM in the power band will help too. Billy22Bob, thank you for your tech onfo. Good things to know. Thank You everyone for your assistance. Happy Wife, Happy Life. Next month she'll have the SRT on Road Atlanta so the speeds will be higher and the stopping less frequent.

 

I agree with the others posts. For Autocross, she should start out in second with the traction control switch in the off position. She can focus on being fast; and only worry about possible downshift if it kicks up to third. It will normally stay in 2nd the entire time unless there is a long straight away, or she loses traction and over revs. out of a corner; which it sounds as though she may be doing.
Edit: Also keep the AC turned off; at least until your done with the hot lap.

 

yes - traction control is a pain - most of the time. When serious driving needed, I turn it off....sorry not to mention before.
I haven't confirmed but I believe it may trip the SC clutch....can someone else assist here?
If my CEL flashes when loosing grip, I can tend to loose power = maybe SC cutout.

 

when it sense tire spin it well close the throttle . if you are data logging and spin the tires you well see the computer temporarily pull throttle.
sc shut off on my car is around 205 iat

 

You need to turn off traction control (ESP).

 

Update: Thank you for all the knowledge and suggestions. After further investigation I discovered the supercharger pump was not operating properly. A few whacks with the back of a screwdriver got it's attention. Come to find out, with the supercharger pump is/was not working correctly (sometimes it came on, sometimes it didn't) the SC was shutting down when it got to warm and came back on when it cooled down. Yes it's a bad pump. I straight wired the pump and it did not initially come on. Thats where the whacks from a screwdriver handle came in. I have a new pump and SC oil on its way. I will install the pump and change the SC oil this weekend. Thank you for all the guidance. This is a great forum with lots of folk willing to share their knowledge.

 

If you have never changed the supercharger oil before, I am told it's best to do in a well ventilated area, or outdoors.
I've seen several references to this on the forum, and all agree that it STINKS something awful, pretty close to barf-city.
One fellow went so far as to say the best way to do it is to have someone else do it. ( Dave, don't go searching for this, I made it up )

 

Now THAT'S funny, right there....

 

I have autocrossed the srt-6 for years and it is a toad. I redesigned and changed the heat exchanger -supercooler- for better cooling, added hood cooling, designed the pulley saver and oil separator in an effort to gain some response and avoid heat issues.

The problem is the computer and had even tried a sprint booster............. but the computer will not respond to the throttle, there is a delay and thats that! Watching the dash dac you see the delay and the throttle is cut when gear changes happen. I had a phantom rear to help traction and ran in first gear to get off the corner - this is how i became aware of our heat sensitivity.

My girlfriend pastes me on the track with her 2000 gt mustang as she has a real throttle body with a cable, nuff said. I have the better posi rear now and well see how this year is as I went to a better intercooler thanks to Rob. But we still have a lot of latency in the throttle body.


I even spent a year and a half trying to get two throttle bodies to work, the computer will not allow more air without bucking. My plan was that two throttle bodies in parallel will open at the same rate and twice the air flow. Remember my dual CAI gave us 25 hp below 2500 rpm? Aint so with two TBs, you will buck and shake something awful as the computer hicckups and shuts off the engine, as the air mass flow is outside its parameters and homie dont play that game. Rob was also trying larger TB but there is a limit that just wont allow it to drive.

OBTW the two TB seemed to work in WOT position but you could get a hicckup now and then and if you do that at high RPM the change in RPM and negative torque will shear off your crankshaft key, spin off the harmonic balancer and generally trash your MONTH. Been there and done that. So the TB is computer controlled and the response is a TOAD.

You have to deal with it on the autocross circuit, and hope you can carry more speed into the corner to get you thru. To that end I have done 18s on all four wheels, slicks on all 4 and also just the rear with no real break thru's. I even have a switch on my Yaw sensor to be sure it was off line, got into rear wheel adjustable control arms back in the day of MikeR, car goes like wheee in a straight line, not so much in the autocross corners.

Sorry, WDY

 

Sounds like someone need to develop a computer programs just for autocrossing - should not be hard, just want to ignore most of the sensors, respond immediately to accelerator position, turn the ABS off, and shift instantly.


One of the best autocross cars I ever saw was a Corvair - 140 hp with a single quad and trombones. You could steer with all four wheels.

 

What if what if what if someone daring like you would try a drive by cable throttle body and leave the original throttle body connected to the harness and just tucked out of the way? Would the nanny ECU be smart enough to catch on?? Also on the dual throttle bodies maybe two N/A 68mm would flow less and not freak out the ECU. Just some ideas!

 

I bought a cable throttle and the computer fights you. Pull off a vac hose which is like opening a mechanical TB and engine goes into convusions as it is not seeing the plate move.

Sorry I broke my pick over this issue and to date have no ideas. Needs computer rewrite to allow such a thing and code writing is not my bag -man. Sorry

Woody