Been a while since I posted. I have a 2nd gen 1500 4WD with a 408 stroker. Truck was dynoed at 350hp and 406ft/lbs at the rear wheels. For the exhaust im currently running Pacesetter LT headers into the 3" off road Y-Pipe then through about 15" of straight pipe into a aero turbine 3030AT and dumping in front of the pass rear wheel. This is all 3" from the headers back to the tip. I was wondering if anyone else running a 408 has a single exhaust or should I be running duals? Right now the truck is entirely too loud and im thinking of swapping to the 3030XL which is resonated but am not against a dual system if it will benefit. I really only went with the single due to the ease of installation and originally I was keeping the 360 and had already purchased the y-pipe. Ive looked online and searched and found a few things that say based on HP I should be running a 3.5" single or 2.5" true duals at a min. Any input would be greatly appreciated. Thanks again, Dennis

 

The 3" single will be fine. Just put a different muffler on there, that has a more acceptable noise level.

 

Thanks for the reply, been a while good to hear from u. When I ordered the muffler they offered aggressive or moderate, I said how aggressive could it be. lol. Its insane!! As short and as free flowing as my exhaust is its really unbearable. Going to order the resonated one and sell this one. It has less that 500mi on it. Just needed another opinion before I ordered it as to weather I should change out the whole thing or not. Thanks again

 

Congrats denn69 on the decent power numbers on your fresh 408 engine. Curious on how your engine is built/set-up? Thanks

 

Thank you Mike, So I took the plunge and Purchased a engine package from Performance Injection Equipment. I opted for the race version of their 408 with a few changes. Instead of the mopar m1 manifold I used a Hughes Airgap and kept fuel injection. Also opted for a bit smaller Cam also. Actually went with the Cam that he offers with the 408 Stealth version. Specs are 224/230 .565/.565 110LSA. It has Edelbrock RPM aluminum heads. I used a 52MM throttle body from HiPoTek. Electric fan from permacool with a 3 row champion aluminum Radiator. Im not crazy about the power numbers, thought the HP would be a bit higher. The race engine is advertised at 523ft/lbs and 522Hp and the Stealth Version is rated at 512ft/lbs and 470HP. I cant remember what he said the engine dynoed at but I figured somewhere around the stealth version. I dont know what the drivetrain loss is but im told around 20-25% for a 4WD auto. If I use 22% then I can figure around 520 ft/lbs and probably 450-455hp at the engine. I have to ask him. He dyno's with a 750 double pump carb so maybe thats the small difference in HP. I was really shooting for low end higher torque. I had the engine shipped to me and i installed it and then sent the truck to him by AAA for him to tune. When it was done I drove down to him with the wife and drove the truck home. There are a few things I may change at this point, Also still have a cockroach or 2 to flush out. I have the trans out now so I can upgrade it a bit to handle the power increase. Basically it was rebuilt 10,000 miles ago, just before I got the truck but even before the engine swap I was getting a TCC code so I knew something was up with the VB. I replaced the front and rear servos and the accumulator with billet ones from MR Randy on the Moparts board. They are some beautiful pieces. Also picked up a rebuilt HD version Valve body from Central Valve Bodies. They do all the updates and some minor plate mods as well for firmer shifts. Replaced the solenoids with a kit from oregon performance transmission to include the billet DNJ governor pressure solenoid and while the trans is down I swapped out the front band lever. Stock ratio is 2.5, I put in a 3.8 which Is stock for the 47RE. My torque converter I used is a 6V from PATC with a 2300 stall however it seems to stall closer to 2600. Im not crazy about the stall converter. I didnt like the way it felt when driving around. Now if I power braked the tires lit right off quick. I also have a Converter from Precision of New Hampton which is their High stall version (I think 1800 or so) I might put that in. Figure it will stall around 2000-2100 then. I have no interest in racing the truck or holeshots, so why do I need a high stall converter to heat the tranny up. Lastly I have a deep aluminum pan for the trans. Here are some pics of the truck and engine and the truck RWHP Dyno. The pics were taken around Oct when I was putting the engine in. The dyno is from FEB when I picked the truck up. I have entirely too much money wrapped up in this truck but it is one of the cleanest 2nd gen rams on the planet!!.U can eat off the frame and underbody. Sorry for the novel figured Id give the whole story. Thanks again

 

Nice build indeed! I will agree that those numbers are kind of low I'll be in 625hp and 790lbs-ft to the wheels when I get my 408 even more when I finish the Hemi. As long as you enjoy it though! Did you restore the truck?

 

Keep in mind, the ratings you get from the engine builder are CRANKSHAFT Horserpower/torque, what you see on the dyno, is rear wheel horsepower/torque. Expect 24-30% drivetrain loss, and your numbers start looking a LOT better. There is likely also more power to be had by tweaking the tune some. Might be worthwhile to invest in the software, so , you can do it yourself. (HP Tuners, they are a sponsor on this site. Complete packages for ONE vehicle for around 500? Maybe 600.

 

Denn, thanks for share your info. Not sure if this helps but you could score a cheap diesel cat back exhaust (typically they run 4in exhaust). The low power numbers could be the dyno jet was set-up, the operator may not of increased the load cell resistance enough so your truck could load up fully. Nice looking truck

I had one of my previous 2nd gen 2500 at 680rwhp and 1200 ft/lbs (5.9 ctd power), tons of money. She was a smokey beast and Prius owner worst nightmare. Tracked low 12's at 6400 lbs.

 

Found the dyno slip

 

Thanks guys. I didn’t restore the truck. I picked it up about 5 years ago in Raleigh NC. it had 104,000 miles on it. I guess things don’t rust down there. I found it on Craigslist and jumped a greyhound from the NY port authority for 75 dollars and 13 hours lol. Bought it and drove it home. It really is immaculate. I’ve put about 10,000 miles on it. I yanked the motor due to power loss. Found severely cracked heads between the valves. Was going to rebuild the 360 then figured I’d go 408. Sold the 360 and grabbed the 408. I would have like to see more horsepower to the rear wheels. Maybe 375 of so but as Hey You said, you have a 20-25% loss in the drivetrain. I was shocked when I got the Dyno, I never knew it was that much. . I had to ask the builder what happened. He explained it. So really I’m at about 510-520 TQ and 450-470hp at the crank. I think the dual plane cost a bit of hp as well as the 52MM throttle body. I should have went a bit bigger but had bought that for the 360 so just popped it on. The cam is also not to radical i could have stepped that up but didn’t want to have to drive at 4000 rpm all day. As far as the exhaust, a muffler change is to easy the way I have it set up. I’d rather not redo the whole system but if I do it will be true dual all the way. I’m in the military and got activated for the craziness that’s going on, got stuck up in Albany NY and found an awesome exhaust shop so we’ll see. For the tune I actually just contacted Flyin Ryan about a remote tune, I hear he is outstanding. Waiting for him to get back to me. How do U guys feel about the torque converter issue I mentioned? Which do u think u would use? Again I don’t race it and once in a while I tow a boat. Thanks again for the feedback.