The following were the responses given by the SRT engineers during Wednesday evening’s SRT Engineers Chat Session:

Air Filter Elements: My car is a daily driver. On the way to work I drive past a rock quarry. At least twice a week the road I drive on is pretty "dusty" for about 1,000 feet. My question is: Will a high performance air filter, such as a K&N drop in filter, provide me with enough filtration?

We recommend using a cold air intake system from Mopar. It will provide the necessary filtration for your daily driver. It will also allow you to wash and reuse it when it becomes dirty.

If I replace the mufflers with glasspacks will I lose power? 07 charger srt8. I plan on keeping the resonators.

Actually, Hemis like a little back pressure. You'd be better off going to a Mopar catback instead.
I have a 2009 Charger SRT8 which is used for a daily driver. I live in Calgary, and the car does stay out in winter. When it gets cold, when first starting up in the morning, I get quite a whine at engine start. It is for the first couple of seconds then it subsides and the car warms up with no issues, do you guys know what this would be? Is this something to take in and warranty or is it just the hemi engine when first starting after being cold?

More than likely it’s the power steering pump, as the fluid warms up and thins out the whine goes away.

Are there any drag racing components (lightweight engine cradle, etc.) on the drag pack challengers that would retrofit into a standard LX and if so are they available for purchase separate from the car?

Most of the unique drag pack components are available from your local Mopar parts dealer. Check the latest Mopar catalog or call the Mopar Tech line at (888) 528-HEMI for specific questions about your application.

Synthetic oil is installed at the factory for SRTs. Some have stated that because synthetic oil is so slippery, the rings and cylinders will glaze and not seal properly. This could result in excessive oil consumption. Any truth to this?

There are lots of rumors that have cropped up regarding synthetic oils. The very first synthetics (like butane in winter fuels and the first alcohols) did have some impact to gaskets and seals (swelling) but that was a long time ago and all modern materials work well with synthetic oil today. Glazing is caused by oil actually burning or Carbonizing in the hone pattern. Synthetic oil does not burn-in, carbonize or cause glazing. The lower friction may delay the break in slightly as it does reduce (slightly again) the wear of the rings and bore but in all our testing the break in does occur within our normal guidelines. If you have excessive oil consumption there is another reason.

Hi, my question is about the 2009-2010 Challenger SRT’s with a 6-speed transmission. There has been a lot of talk on the forums lately about the wheel-hop problem with these cars. In the last SRT chat session on the Jeep forum the question was posted to you guys asking if you were working on a fix for the problem, but your response was more of a “how to drive the car without spinning the tires” instead of answering the question. I would like to ask it again, and I would appreciate a direct answer to these 2 questions: Are you guys working on a fix for the wheel hop problem on the 6-speed Challengers? If you are, will it be something that people who have already bought these cars will be able to take to their dealer and have repaired at no cost? Thank you!

Per last months WebChat...."Powerhop is, unfortunately, an unavoidable hazard in making big power with a manual transmission. From a design stand point, lowering the clamp load on the clutch would smooth that out, but the trade off is smoking the clutch after just a few launches. My recommendation is to keep working on your driving technique. It sounds like you have the handle of it in 1st. Remember, if you are power hopping the rear end you are not getting the best launch you can. And you're beating the crap out of the rear end. Could have something to do with the whine you are starting to hear. I would not worry about the axle gear wearing out, but if the pattern moved even slightly from the initial position set in the factory it will get noisy. If it's really driving you nuts you might consider taking it in, but if it's only there for a small speed range it's not an indication of wear-out or pending doom like a constant growl noise would be."

If you see a data log of any 5.7 (maybe 6.1s also) 6-speed car, you always get some short-term knock retard during the shifts. It has nothing to do with gas quality or octane (happens with 100+ octane race gas), and only happens during the shifts, so there's a lot of speculation that it's simply engine or trans noise being picked up by the knock sensors. Most folks just say 'that's normal', but since it costs a couple of degrees of timing, it would be good to get rid of it. Any thoughts?

Unfortunately, there is not a solid to do this. Your friends are right, its due to the noise that is put through the power train during the shifts. Given our knock sensor location and the algorithms used, this is what we have to deal with. I know its not the answer you want, but its the truth.

Is it possible to run E-85 in a '07 6.1 Charger? E-85 has 100 a octane rating and it seems that it would be an economical alternative to super unleaded. What are the limiting parts / factors to making it flex-fuel friendly? What would happen if we used E-85 in the car? (Yes I realize fuel efficiency goes down, but I already paid the gas guzzler tax) Why did you choose not to make it compatible right off the bat?

Due to the lower energy density of E85, the fuel injectors cannot deliver enough fuel to sustain combustion at high loads (the typical SRT owner driving style). Lean burn conditions and meltdown are potential issues. Also, the fuel delivery system (seals, lines, and tank) was not designed with the corrosive properties of E85 in mind. There is a high potential for component issues with E85.

What causes the Hemi “ticking” sound that is heard in idle and just off idle? I have read that it is caused by a lack of cushioning of the intake/exhaust valves and fuel injectors, and wearing off of the moly piston skirt coatings.

You will not hear the valve seating at or near idle conditions unless you have seriously aerated the oil system and hence the lifters. You will also not hear the moly wearing off the piston skirts. A piston that is too small in a bore too big will result in a cold slap that can be heard at cold (I mean cold like -20 deg F) idle. We do a lot of testing and guage pistons and bores very carefully to make sure you as our customer cannot detect the piston movement in the bores - hot or cold. I expect what you hear is the injectors which do make a clicking noise that can be heard and gets slightly noisier as the injector temp is elevated. The noise is caused by the injector pintel as it opens and closes and while we have not been able to eliminate the noise due to the required operation (you need the fuel) we have done some work with minimizing the noise with isolation -see some of our new stuff - oh wait I cannot talk about future product.

There is a lot of welding bead inside the port of the SRT’s clam shell headers. Would grinding them smooth produce a better air flow and any more horsepower?

The tube in shell does have welded edges that may show slightly more flow if they were "touched" or "blended" but to do so may cause that area to crack therefore ruining your manifold. I would not recommend it they are expensive to replace.

What would be the first Mod you would do with $500.00 on a 2010 Charger SRT?

Probably Cold Air. Lots of good stuff in the catalog:

http://www.mo-pod.com/pdf/09_Perform...log-120908.pdf

Some of the opinions on our wheel hop on the 6-speed Challenger's is the rear sub frame movement. What would the negatives be if the subframe was bolted tight against the car frame?

There would an increase in the amount of driveline vibration transferred though the rear cradle into the body.

I own a 2009 SRT8 Challenger 6-speed. I know the car comes from the factory with ATF+4 fluid. What is the proper fluid amount? I was told there was a change last summer?

3210ml

I'm planning on building a Challenger road racer. I assume (maybe incorrectly) that starting w/ a Challenger SE would be more cost effective than using an R/T or SRT. Do SRT brakes, suspension parts, and drive line directly bolt in to an SE body? Are the brake master cylinders different on the SE and the SRT? If only Mopar would sell me a body in white......

SRT's do not have unique body in white, so all of the suspension joints to the body are in the same the base platform vehicles. And don't give up hope. Before you embark on this project call 888-528-HEMI for the latest on the BIW program.

I see the Challenger has a rubber bushing material on both ends of the driveshaft. How strong is this material on the 6-speed cars? Consider I would be using drag radials and have 400 horse/torque to the tires.

If you have an SRT you should have 425/420 horse/torque. We have done a lot of testing to ensure those couplings live. Believe it or not the hardest part was keeping the bolts from bending. Notice the pretty pink bolts, don't use anything else, they will bend and lose clamp load. That said we have been very happy with the strength of this joint. We did do some testing with drag radials, and saw no issues.

Will the composite intake manifold from the 5.7 Hemi fit on the 6.1 Hemi without any major modification? With minor modification?

I believe it would fit but why would you do it? It will save weight but the runner system is not properly sized to deliver the air you need to go FAST. I only assume you want to go fast because we do. Some of the new dual runner adaptive intakes (2009 5.7L truck) could extend the torque band and allow a different feel but that option requires actuator electronics to make completely effective (or some cable controls and an extra person to move the controls when you yell).

I really need to know if 6.25 quarts (putting my level at full) puts my car at the proper amount of oil, or am I driving my car every day three-fourths of a quart low?

We certainly call our 6.1L oil system a 7 qt system. Discussion here in the room requires that we (read I will have to) go back and retrace some of our test data/results and get back to you at the next session. Sorry.

My engine was dyno tuned those number are to the tires. the base line was 360 hp to the tires.

Is this the same coupling you have been using in the charger platform? No difference between auto or 6-speed?

We went to a larger (thicker coupling) for 2009 to handle the manual trans loads and the auto changed along with it. The trans end is different, but the axle end is same for both auto and manual.

Thanks for adding the Getrag LSD. I retrofitted one in my car and it has been taking a lot of beating including 1.48 60' times. I've heard some have had problems with the clutches going bad and others (including me) hear a whine at part throttle at certain speeds. Are you guys happy with this rearend? Also I hear there are no rebuild kits available right now, what gives? Also, some folks have been making 1/4 mile runs without the serpentine belt. Basically start burnout with coolant temp below 120*, stage, run and shut down when temps are 180* or a little higher. Obviously there is some danger here to the motor. What do you think is the most likely thing to break first when the water pump and alternator aren't running at the drag strip?

We are very happy with the Getrag LSD. Unfortunately, production tolerances can often lead to slight whines at any given load condition (full throttle, part throttle, accel/decel). It is important to monitor this whine to see if it changes with age and wear. What is most likely to break when you run without the water pump? THE ENGINE!!!

Any response on how to make the car act more like a muscle car as opposed to a lethargic giant awaking from hibernation. Another posted on throttle response and the adaptive programming and how it is lacking to really adapt to our liking! Driving around in the suburbs with your foot in the throttle tends to catch attention of local police, scare small children and furry pets. But when the opportunity exists for some spirited driving, we want a SRT branded car to step up to the plate!

Thank you for the feedback and your continued support.

 

In my view, they need to make whatever necessary changes to getting the injectors and pumps to work with E85 in models that require premium fuel as well as using the proper components. For people who live in E-85 states who like to mod their cars, this is an ideal fuel to use, not to mention the fact that E-85 only makes sense as a racing fuel and not as a fuel to use in a bland model. The marketing, concept, and execution is completely backwards using it in practical models, E-85 is for performance purposes and performance purposes only.

 

Agree on E85 perception vs reality. High octane and lower mpg is a recipe for performance cars rather than economy.

I believe, having read some articles about E85 in the past, that it adds cost to make the fuel system E85 friendly. Maybe it was not deemed worth it to add the cost of E85 capability, given it's limited availability and the broad perception that it is a "green" rather than a performance fuel.

I was a little surprised that he said the fuel system could not deliver enough E85 to support a proper air-fuel ratio at high loads. E85 has about 75% of the energy density of gasoline, certainly lower but not insanely so. Well...doing the math it seems to make more sense, I guess that would call for about 1/3 more fuel for a given amount of power. (3/4 the density x 4/3 the volume gives an equal amount of energy). So maybe the injectors only have say a 25% safe reserve capacity. There are implications for what this would mean on upgrading the fuel delivery system when making more power, but I think I'm already beyond my engineering expertise