LX Forums Forum banner
Status
Not open for further replies.

SRT Engineers Roundtable: 08/05/09

121K views 164 replies 89 participants last post by  DMAG 
#1 · (Edited by Moderator)
SRT Engineers Round Table Discussion​

Wednesday, August 5th 6pm - 8pm

The ground rules:

  • First off, the SRT Engineers take time out of their busy schedule making go fast goodies to be here to answer our questions. Let's show them the proper courtesy and patience. There will be many questions and they may not be able to answer every question asked. If your question is skipped, please be patient as questions are not answered in order.
  • Please only ask one or two questions. There are lots of people who want to ask questions, so let's give everyone a chance.
  • Stay on the topic at hand. SRT Vehicles! Keep the off-topic chat to the other sections of the website. There is to be no discussion between members in this forum. Ask your question and enjoy the replies from the Engineers!
  • If your question has already been asked (by you or someone else). Don't re-post it in hopes to get it answered quicker.
  • Make sure you let the SRT Engineers know what model SRT vehicle you are driving or inquiring about. Yes, a head gasket is quite different between an SRT8 and an SRT4. ;)
  • As much as everyone is salivating over what comes in the future, the SRT Engineers cannot answer any questions regarding future product. This INCLUDES 2010 line products.

This thread is now open so you can start posting your questions.
 
See less See more
#3 · (Edited)
Please explain the oil specification of Mobil1 0W40 --

seems that 5W40 or 10W40 covers the same ground for most ambient temperature applications.

part 2: will SRT authorize or waive the 0W40 to allow use of Synthetic 10W40 or 5W40? (especially in Texas where the low ambient is 25 degrees F)

my car: 07 MSRT8 x 2
 
#85 ·
Please explain the oil specification of Mobil1 0W40 --

seems that 5W40 or 10W40 covers the same ground for most ambient temperature applications.

part 2: will SRT authorize or waive the 0W40 to allow use of Synthetic 10W40 or 5W40? (especially in Texas where the low ambient is 25 degrees F)

my car: 07 MSRT8 x 2
You are correct the only significance in the low end of the oil weight 0W vs 5W vs 10W is the improved performance in the very low temperatures. We certify for the entire nation so we pick the best product for use for everyone. Mobil has told us the 0W40 has the most stable additive package of the multivis synthetic oil group. In truth you can use any of the Mobil synthetic oils you have mentioned without concern. Dodge will not quibble with any of these selections especially for 25deg F low temps.
KC
 
#5 ·
SRT Half Shafts. Years 05-08.

I understand there were some issues during production that caused breakage on stock vehicles due to some batches being weaker than others.

1: Were these mostly experienced during 05-06 since it was a new product or was it continuous and was the problem with improper heat treat solved in later years?
2: Is this problem based on a batch to batch circumstance where a bunch of cars made a certain times will have weaker half shafts than those produced at other times?
 
#6 ·
I had a Manley exhaust valvespring break when I was out at the LX and Beyond Nats a couple of weeks ago. It broke on my last run down the track. We (the Hemi community) have had problems with Comp Cams springs in the past and are now having problems with Manley springs. Does Mopar Performance have a spring that will work this cam? And if so, why is it better than the Comp or Manley?

 
#77 ·
Vlave spring options

Hello,

I think we may have talked at the Mopar Nat's a few weeks ago!

Valve spring problems like you are experiencing are generally due to poor valvetrain dynamics and is most times the result of camshaft profiles that are too aggressive. Generally speaking, the conical valve spring design is limited in it's ability to control extreme valvetrain motion as effectively as conventional race spring design, but due to the packaging limitations in the head and the relatively short spring heights used in the current generation Hemi, spring options are severely limited as you have found.

In our development and testing of the Mopar Performance parts line of valvetrain parts, we found the Comp Cams 918 spring to be the best available spring for the Hemi application. It is my understanding that Comp may have had some recent issues with materials as a part of their revised spring design and finishing process that was implemented later in 2008. My conversations with the engineers at Comp suggest they have resolved this issue in later product. Given that you have broken a spring, I would recommend contacting Comp Cams engineering department to discuss the problem you had and return the set of springs to them for analysis and possible upgrade recommendations.
 
#7 ·
Initially our 6.1L were designed to use 0W40 Mobil 1, its on the oil cap and in the SRT's car manual. The bankruptcy brought about a falling out with Mobil 1, now all the dealerships are using 5W40 in the SRT 6.1L motor. From an engineering perspective is this change OK for the 6.1L? Why the change in viscosity? Thank you.
 
#102 ·
Yes the change in viscosity from the 0W to the 5W will only show up in very low ambiant conditions (-20deg and lower). The closest synthetic oil from Penzoil/Quaker/Shell available for all of our sales areas required this small change in low end viscosity. In truth any quality synthetic oil with 0-10W40 multivis oil will be fine for your 6.1L. If you are running it hard or in very hot climes use the 10W40 (or even 15W50 on the track). If running in very cold climes move it down 0 or 5W40.
KC
 
#8 ·
Can you please give me the production numbers for the Canadian Magnum SRT8s. I own a 2006 Inferno Red Magnum SRT8. I have heard that there was 666 Inferno Red Magnum SRT8's in 2006, does that include the Canadian ones?
 
  • Like
Reactions: Jaak
#9 ·
Thanks again for attending LX&Beyond, and for the chat session Saturday night. Anyway, id like to carry over some questions that were made there about the 226 getrag rear differential.
Clutches, could we get a repair clutch kit number produced, or shim kits to make the packs tighter?
Rear drive shaft. Currently its required to buy the entire drive shaft. Can we get a rear section only number supplied?
 
#117 ·
Thanks again for attending LX&Beyond, and for the chat session Saturday night. Anyway, id like to carry over some questions that were made there about the 226 getrag rear differential.
Clutches, could we get a repair clutch kit number produced, or shim kits to make the packs tighter?
Rear drive shaft. Currently its required to buy the entire drive shaft. Can we get a rear section only number supplied?
We had a great time a LX&Beyond and look forward to doing more event like it in the future. As for the clutch pack parts... Have you had an issue with the LSD clutch pack? If so, is it damaged or are you getting one wheel peel? We have discussed additional bias ratio options but haven't seen much need. If there is a need, please let us know more. BTW, additional bias ratio will negatively affect turn-in response.
 
#10 ·
Not a technical question, but one we'd all like to know the answer to.

We realize with corporate structures, there comes budgets (some smaller then others, especially in these rough economic times). What features of the SRT vehicles (specifically the LX platform SRT vehicles) got left on the cutting room floor? What features did you want to see added to the SRT's that the budget did not allow for? (minor/major).

Thanks again for bringing your knowledge and expertise to LXForums! :)
 
#11 · (Edited)
Thanks again for the chat in Ohio and welcome to our forums.

Where can we get all the parts to the LX SRT8 Brembo calipers , separately, i.e. pistons, pressure seals, mating grommets (front), etc.?
I did get some dust seals through Chrysler parts.


Thanks...Jonn
 
#13 ·
First off, THANK YOU for doing this chat here on lxforums. I realize that this is outside of the original design specs of the 6.1, but we have quite a few cars running boost around here. Several have had piston failures at the top ring land. These failures appear to be due to high heat causing the ring to go solid and arch up into the land.

We now have forged pistons with a thicker top ring land available to replace the stock piston. So how much boost do you think the stock rods can handle? I don't think we've seen an OEM connecting rod break without a piston failure first.
 
#91 ·
Turbo boost vs. rods

Fortunately, and somewhat counter-intuitively, moderate forced induction pressure levels are relatively easy on rods PROVIDED there is absolutely no evidence of pre-ignition or knock. However, the production rods were never designed for boosted applications, there really is no safe answer to this question. Having said that, the 6.1L rods are fairly robust in naturally aspirated applications. However, I would say the safe answer is to suggest that in any boosted engine, all internal components should be considered for upgrade much like your decision to upgrade pistons.

First off, THANK YOU for doing this chat here on lxforums. I realize that this is outside of the original design specs of the 6.1, but we have quite a few cars running boost around here. Several have had piston failures at the top ring land. These failures appear to be due to high heat causing the ring to go solid and arch up into the land.

We now have forged pistons with a thicker top ring land available to replace the stock piston. So how much boost do you think the stock rods can handle? I don't think we've seen an OEM connecting rod break without a piston failure first.
 
#14 ·
1) What are the specific changes made to the Mopar TCM vs. stock ???

2) What are the commercially available software packages that allow the reprogramming of the Siemens TCM's that our cars use...and why have attempts by some programmers seemed to have been overwritten after some time ???
 
#80 ·
1) What are the specific changes made to the Mopar TCM vs. stock ???

2) What are the commercially available software packages that allow the reprogramming of the Siemens TCM's that our cars use...and why have attempts by some programmers seemed to have been overwritten after some time ???
To quote the I-sheet:

"The MOPAR Transmission Controller Upgrade has an optimized shift schedule to take full advantage of the MOPAR 5.7L Hemi Performance Camshaft and Performance Torque Converter. The performance tuned AutoStick® calibration with hold in-gear feature will prevent the transmission from up-shifting at red-line RPM in AutoStick® mode allowing for sportier driving."

Our cal was developed intrenally by the same people who work on the production controllers which gives them a leg-up on what's going on in the aftermarket.

 
#17 ·
The factory manual lists the ring gap specification for the 6.1 as: Top compression ring .0118 - .0157 and the second .0137 - .0236. I recently inspected a motor with 30K miles on it. The top ring was close to spec and measured .012 - .015 but the second ring averaged .036 - .039. Is it possible the second ring was gapped at the factory wider than spec or is this simply wear and the type of material used. On the 09 6.1's, have the ring gaps or ring material been changed and if so, can you provide the specification?.
 
#98 ·
Ring Gaps

Actually, I am almost positive the second ring gap specification printed in the manual is incorrect. The actual gap is quite a bit wider than you indicated and much closer to what you have observed (though I can't put my hands on the spec right away, I think it's closer to .018 - .032" but don't quote me). Since the introduction of the 6.1L engine into production, the ring design and material has remained unchanged.

The factory manual lists the ring gap specification for the 6.1 as: Top compression ring .0118 - .0157 and the second .0137 - .0236. I recently inspected a motor with 30K miles on it. The top ring was close to spec and measured .012 - .015 but the second ring averaged .036 - .039. Is it possible the second ring was gapped at the factory wider than spec or is this simply wear and the type of material used. On the 09 6.1's, have the ring gaps or ring material been changed and if so, can you provide the specification?.
 
#18 ·
I have a question in regards to the Stock kicker audio system. Is the Stock amp the same as teh 77kick18 amp upgrade? Chryslers sales literature states that that stock kicker amp is 322 watts, and the 77kick18 is 368. Is there a difference?
 
#19 · (Edited)
1. If you could make 3 performance upgrades to a 2009 Challenger R/T 6 speed what would they be?

2. With the top ring being 3mm from the top of the piston, is there such a thing as a "safe" amount of boost in a supercharged application on the 5.7L motor, and if so what is the "safe" psi level? (assuming a proper tune of course).

3. If a Diablo Predator tune is put on the car, then flashed back to the stock tune, can dealer equipment see that tunes have been swapped back and forth?
 
#21 ·
Brembo Brake Dust.

While attending an SRT Experience last year, one of the instructors mentioned they used a spray or compound on the rims to eliminate the build-up of brake dust on the rims. I never got a chance to re-connect with that instructor that day, do you know what they are using on the Experience cars for the brake dust problem?

Thanks.

Don
 
#83 ·
Brembo Brake Dust.

While attending an SRT Experience last year, one of the instructors mentioned they used a spray or compound on the rims to eliminate the build-up of brake dust on the rims. I never got a chance to re-connect with that instructor that day, do you know what they are using on the Experience cars for the brake dust problem?

Thanks.

Don
Not sure what the TE instructors were referring to, but we recommend using the Mopar wheel cleaner.
 
#22 ·
Thank you to all the SRT engineers for taking the time to answer all of our questions. I have truly enjoy my charger SRT8 from day one. Question is, why does this vehicle have so much hesitation when you step on the gas pedal? seems like it winds up and then shoots out. It feels like it builds up power, then realeses it.
 
#23 ·
Seeing that Chrysler isn't using Mobil 1 in the 6.1 Challengers, what weight and manufacture should we use. Just had the oil changed in my 08 Challenger at the dealer, and the receipt did not specify the weight or manufacture.
 
#112 ·
For our products direct from the factory we are filling our SRT engines with Penzoil 5W40 synthetic. Any quality synthetic wide range multivis can be used for continued service. Certainly the recomendations would include Mobil 1, Penzoil platinum, Quaker Qpower, or Shell Helix as quality synthetic oils.
KC
 
#25 ·
Thanks again for all your time. From the SRT-4 I owned to now with the R/T Magnum, great job!! Of course I would love to know if the 6.4 Hemi has been canned but its a possible future product.

1.) Why has the MDS system not been added to the 6.1?
2.) Personally do you think that the VVT on the new gen 5.7 makes the older 5.7 not worth the time for a engine build or the older one less prone to failure?
 
#26 ·
Thank you SRT Engineers for taking time to answer questions.

I have one problem with my SRT-4 Caliber and I have taken it to 4 dealers here in South Florida and all of them tell me there is nothing wrong. My husband even had one of the mechanics in the car when it happened. Here is what it does:

I am driving the car and maybe make a hard turn right or cross the rail road tracks I hear a loud "pop" when this happens. Its up on the right side of the car toward the front. This can't be normal. What do you think it is??

Thanks for any help.
 
#131 ·
Thank you SRT Engineers for taking time to answer questions.

I have one problem with my SRT-4 Caliber and I have taken it to 4 dealers here in South Florida and all of them tell me there is nothing wrong. My husband even had one of the mechanics in the car when it happened. Here is what it does:

I am driving the car and maybe make a hard turn right or cross the rail road tracks I hear a loud "pop" when this happens. Its up on the right side of the car toward the front. This can't be normal. What do you think it is??

Thanks for any help.
Could be a couple things. There was a LCA bolt change, have you had this looked at? Also check the torque on the front suspension craddle bolts, there are 4 of them. I would put the torque at the max spec (163Nm). If the bolts are torque all the way up the crossmember can move and it does make a loud noise.
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top