LT's on an AWD?

[HemiRedMagnum]

I have a 2007 AWD 5.7 Magnum and was wondering if anyone has tried to fit longtube headers on there LX? I know one member was talking about a custom tranny bracket? ANd how much more power is there between Shorties to Longtubes? Thanks for any help!

[Midnightsun300c]

I have a 2007 AWD 5.7 Magnum and was wondering if anyone has tried to fit longtube headers on there LX? I know one member was talking about a custom tranny bracket? ANd how much more power is there between Shorties to Longtubes? Thanks for any help!

That would be me. On the subject of hp and torque difference between LTs and shorties there are a number of considerations.

• Which brands are being compared?
• Are high flow cats part of the equation? If so which makes and brands?
• Is high flow exhaust part of the equation? If so which makes and brands?
• What mod's have been done to your engine to date?
• What mod's are planned for your engine?
• Has the tune been optimized on the "before" dyno?
• Has the tune been optimized on the "after" dyno?
• When you speak of power are you asking about torque or horsepower, or both?
• Are you looking at the difference in gain at a given rpm?

You have probably already seen a number of seemingly conflicting advertisements claiming this or that gain. I have noticed it is common for a vendor or manufacturer to show gains that include either the cats or exhaust so that it is impossible to know how much of the gain is the header. It is also common to show peak hp gain and not address what the increase is throughout the rpm range. Many times what you gain in one part of the rpm band you lose in another.

That all being said the average advertised LT hp/torque gain over shorties that I gathered at the time I bought my LT's was somewhere between 5-10 hp. I think it safe to assume that the more heavily mod'd the engine and the higher the rpms the difference between the two become more.

[HemiRedMagnum]

I was probably going to go with Dynatech's also with the high flow cats. So you made the Bracket? DO you have a diagram or model or could you make another one? How hard was it to do thanks alot!!!

[Hemi31]

You put LT's on an AWD Midnight?Please post some pics of this as I would love to put Mopar headers on my AWD.

[Midnightsun300c]

I was probably going to go with Dynatech's also with the high flow cats. So you made the Bracket? DO you have a diagram or model or could you make another one? How hard was it to do thanks alot!!!

I would be happy to post some picture when I get off of work tonight. The replacement is quite easy once you've done it. The general process was:

• Drop the exhaust
• Drop the transmission brace
• Make a cardboard jig by tracing the contact area of the brace. Make as exact as possible the measurements of the stud locations.
• Get a mock in slag 3/4" steel cut
• I oversized the stud holes and used oversize washers to insure a perfect bolt up
• Fit it to the transmission and note any necessary dimensional modifications
• Get a high grade 3/4" steel cut from your modified dimensions (if any)
• You will need new bolts along with the oversized washers as the steel replacement is much thinner and the old bolts are too long.

The basic conflict with the LT's on my AWD was the depth of the aluminum transmission brace. With a flat 3/4" steel there is no more conflict and the headers bolt up with the exhaust quite well. The 3/4" is probably overkill and you may be able to get away with 1/2" but for the 1/4" of clearance difference and few pounds of extra weight I was happy to be on the safe side. It has held up for over 18 months now with no flexing or movement issues.

It has been long enough now that I have forgotten the bolts/threads size etc. I may have kept them somewhere. I doubt I still have the cardboard jig but I may have taken a picture of it. I will have a look for them tonight.

Remember that this is on a 2006 300C AWD. Your brace may be somewhat different but the process should still be the same.

[Midnightsun300c]

You put LT's on an AWD Midnight?Please post some pics of this as I would love to put Mopar headers on my AWD.

If I can find the old pictures I will post them tonight. If not I'll take some new pictures of it installed.

So how is life with both FI and nitrous?

[UBR RT]

I heard that the Kooks fit. I'll be adding them shortly.

[Midnightsun300c]

I heard that the Kooks fit. I'll be adding them shortly.

Any LT headers (that I've seen) that fit a 2WD will fit an AWD. It's the ability to connect to the exhaust that is the problem. The stock transmission brace is at the same elevation as the LT header collection tube outlet. Without addressing the transmission brace you would have to put some pretty severe and restrictive 90 degree bends in your exhaust/header connection and probably end up with 3" less ground clearance...at least on a 2006 300C AWD.

[HemiRedMagnum]

Cool great replies cant wait for some pics Thanks!!

[Hemi31]

If I can find the old pictures I will post them tonight. If not I'll take some new pictures of it installed.

So how is life with both FI and nitrous?

well.....still need to do some work on the F/I and I haven't got enough fuel capacity to run the nitrous so the CC will be busy the next few weeks.

[Midnightsun300c]

well.....still need to do some work on the F/I and I haven't got enough fuel capacity to run the nitrous so the CC will be busy the next few weeks.

Are you going to be using a voltage regulator/boost-a-pump or have you got designs on a replacement pump? With water/methane and nitrous there's no telling how much combustion chamber pressure you can run without detonation! Put on an intercooler and you could probably blow the heads right off without any detonation! Sounds like an ambitious project. I'll PM you for more details.

[Midnightsun300c]

I hope the following pictures help. I couldn't find any pictures or notes from the install.

Transmission brace directly above exhaust

Left header collection pipe, 02 sensors, cat

Right header collection pipe, 02 sensors, cat

Right side bolts of replacement transmission brace

Left side bolts of replacement transmission brace

Center bolts of replacement transmission brace

Left side view of car bottom to show headers and exhaust hang about level with everything else

Front looking back to show headers and exhaust hang about level with everything else

[madeulooq]

I'm impressed.. good job Midnight, How'd u go about the replacement brace? was it custom made or did u buy it from somewhere?

[Midnightsun300c]

I'm impressed.. good job Midnight, How'd u go about the replacement brace? was it custom made or did u buy it from somewhere?

After I removed the stock brace I traced the silhouette onto a piece of cardboard and transfered the bolt pattern by measurement. The cardboard was used as a template to create a rough draft that could be fitted and marked for modification and in turn be used as a template to cut the final piece of steel. A local metal fabrication shop did the cutting. I think they only charged me $140 for both the low grade draft and final tempered steel cut with a water table.

[HemiRedMagnum]

Great pics! Did you go with the Dynatech headers and high flow cats and mids? Did you get them jet hot coated and would you recommend coating? Thanks again!