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5.9 Engine Mods

19K views 18 replies 7 participants last post by  hound 
#1 · (Edited)
Hey guys, finally got off my ass yesterday and spent some serious wrench time on the 5.9. Here's what I did:

  • K&N FIPK
  • M1 Intake
  • Harland Sharp 1.7 Roller Rockers
  • BBK Twin 52mm Throttle Body
  • Mopar "Jeep" Cast Aluminum Valve Covers
  • Silla Aluminum Radiator
Here are some pictures:

Overview - Good look at K&N

Passenger Side - Good Look at Valve Cover, Intake, and TB

Driver's Side - Airbox and Custom Breather setup

Close-Up of Intake




Comments:
  • I learned my Jeep is the perfect height that it strains my hamstrings to lean over the engine for any extended period of time. This is the first time in my life that my legs are sore from working on a vehicle.​
  • The M1 intake is an absolute work of art! Way better than that stock POS. They are darn near impossible to find these days, but if you have the opportunity to get your hands on one, GET IT! The engineering is what you'd expect from the group that designed the engine in the first place - no detail is overlooked.​
  • Roller rockers were way easier to install than I expected and made a bigger difference than I expected. Most unexpected difference - changed exhaust note. Definitely sounds throatier now!​
  • If you go with the Mopar Valve covers like I did, be prepared to fashion some sort of custom breather/PCV setup. I don't know if I was supposed to get grommets and shit with the covers, but I didn't. I got a regular chrome breather (3/4" neck) and a couple of universal 1.25" OD x 3/4" ID grommets from the local NAPA. Then, I had them look in the back for a PCV valve that fit into a 3/4" grommet and had a connection for a 3/8" hose. This seems to be working well so far.​
Let me know what you guys think!​
 
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#3 ·
Lol, thanks. Here are some more pics:

Another shot of the intake & TB


Better view of Passenger Side (Last one was fuzzy)


Radiator - Sorry, the thing is pretty much completely covered


Airbox


 
#4 ·
So, I've now obviously got the intake side of the engine covered. Please don't think I was ignorant enough to ignore the exhaust side. I've had a set of Doug Thorley headers on order SINCE MARCH 8TH!!! Those bastards are terrible. I called today and they told me that they just went out to ceramic coating so I should have them in less than a month. We'll see. I also have a matching Kolak 3" exhaust to go with the headers, complete with a Flowmaster 50 series and Magnaflow hi-flo cat and SS tip. I'm excited to hear that thing growl!

But, I'd like to take this opportunity to tell everyone:

DO NOT WASTE YOUR TIME OR MONEY ON DOUG THORLEY HEADERS!!!

Yes, they do make a good product, but their customer service is nothing short of the worst I've ever had the misfortune to deal with. Again, I placed my order with them for my headers on March 8th! Here we are, over 6 months later, and I still don't have them. And their attitude the whole time has pretty much been "deal with it".

If the Edelbrock headers weren't so horribly inferior in quality, I would have cancelled my order with Thorley long ago. As it is tho, they are the only game in town if you want a quality header for the Jeep. However, if I ever do an exhaust on another vehicle, I am gonna steer clear of anything with the Doug Thorley name on it. I suggest all of you do the same.
 
#5 ·
Sorry to dig up a semi old thread, but I also am the proud owner of both a Jeep SRT8 and a 5.9. I need to get my siggy updated lol. My 5.9 is my DD but I'm doing some mods anyway. I thought I'd seen elsewhere that the M1 was a waste of time? But perhaps doing the 52mm TB is what makes it all work? Any tips on the install of the M1 and RR's? I don't yet have too much in the way of mods.... K&N intake, Mopar ECU and the 249/242 swap. I've got a Magnaflow/Carsound Cat plus a Flowmaster 40 Delta Flow in the garage while I wait for Kolak's 3" exhaust and ignition upgrade to arrive. Can I ask what you paid for the M1 and where you found it? Same for the RR's?? I think I saw some on Summit. Thanks in advance for your help. -Marc
 
#7 ·
I don't think the M1 intake is a waste at all. I think what you've read is that the M1 isn't useful until you get the rest of your vehicle worked out. What I mean by that are things like throttle body, intake, and exhaust. I'm probably not getting the full benefit since I have the stock exhaust system still in place.

I got the M1 from some dealership on the net. I bought the valve covers and some other stuff too, but I seem to remember paying like $480 for the intake. They're getting pretty hard to find, so you should jump on it. Install of the manifold is pretty easy - Mopar thought of everything. One tip I will give you is that after you get the old intake off, use a Shop Vac and a gasket scraper to get all the old gasket crap off. I was afraid of scraping it at first lest I drop some in the ports/lifter galley, but if you stuff your ports with rags, you can just scrape to your hearts content and then use the Shop Vac to suck it all up. Honestly, it worked way better than I ever could have imagined!

The roller rockers I got from Summit. There were a few places that were cheaper, but Summit actually had them in stock. Everyone else had to order them in and I had plans to do them before they could get them to me. I got the non-adjustable ones, Harland Sharp P/N S70037. They are a snap to install. All you do is bolt them down and torque to the specification. Done. No crazy torquing pattern to follow or anything like that. The only downside is that they are NON-adjustable. This takes away your ability to compensate for pushrod length in the event you change cams. Basically, if you are planning to stick a different cam in, you should go adjustable. If you don't have plans, go non-adjustable.

I haven't decided if I want to go with a different cam in the future. All hope is not lost in my case. If I do decide to get a bigger cam, I can just get a set of custom-length pushrods. Not the cheapest option, but cheaper than buying a new set of rockers. Also, bear in mind that if you go with the adjustable rockers, you will also need to get studs and guide plates.

Hope this answers your questions.

CANCEL your order if you still can and get the Edelbrocks.
I have to respectfully disagree. I feel that in terms of product quality, the Thorley's have the edge. They have 3/8" flanges and 14-ga tubing. I don't know what Edelbrock uses but I don't think it is that stout. Also, the Thorley's come ceramic-coated and are a tri-y configuration, as opposed to Edelbrock's 4-into-1 design. Tri-Y's are much better for lower RPM operation (aka street driving). Lastly, and this is what stole my vote, is the "merge" section, or y-pipe, where the left and right banks combine.

If you compare the two, you'll see that Thorley's y-pipe is a MUCH better piece. Edelbrock's doesn't look to be much better than the stock piece, which was one of the major reasons why I wanted to get headers. Surely that has to be a major flow restriction. All in all, I just think the Thorley's are a better product.

Now, that being said, from a CUSTOMER SERVICE standpoint, I don't think anyone should ever waste their time with Doug Thorley headers if there is a suitable alternative. In my case, as I just explained, I didn't feel there was a suitable alternative, so my choices were to either deal with Thorley's subpar customer service, or go without headers. Seeing as how I spent thousands of dollars making the engine inhale better, I really didn't see leaving the stock exhaust in place as a good option. Thus, I have kept my order in place for the Thorley's.

BTW, they are boxed and ready to go as of Tuesday last week. Now we are having administrative problems. Oh brother.
 
#8 · (Edited)
Looks great but that M1 wasnt a good idea on a stock motor. Hurts bottom end and doesnt do much of anything for your top end either. Ported kegger is the way to go unless you are going to runa cam, heads, blower, stuff like that.

Thye M1 may look better than the stock "POS" yet the the kegger makes more power dyno proven over and over again. Ill take performance over looks.
 
#9 ·
Looks great but that M1 wasnt a good idea on a stock motor. Hurts bottom end and doesnt do much of anything for your top end either. Ported kegger is the way to go unless you are going to runa cam, heads, blower, stuff like that.

Thye M1 may look better than the stock "POS" yet the the kegger makes more power dyno proven over and over again. Ill take performance over looks.
Damn! I was told the complete opposite. I was told the M1 makes more power as long as you have other mods done (tb, K&N, exhaust, etc). Got any links to this dyno info?

That being said, what I will say is that I can feel a significant difference in power. What exactly it is coming from is anyone's guess. My guess would be all of them working together. And I am salivating at the thought of how much better it will be with the headers/exhaust. With how free-flowing it is on the intake side, it's gotta be choked up pretty good through the exhaust.
 
#12 · (Edited)
KOLAK seems to be the only one who really loves the M1 on a pretty much stock motor. IMO the Hughes/Edelbrock airgap manifold is the way to go. When i have an extra $600 laying around thats the manifold oll be going with lol. The M1 DOES help over 3500 rpm or so but seems to hurt lower end some. The Hughes?Edelbrock combo seems to pretty much leave low end alone and kick in about 2500 rpm and helps above there. The 5.9 is an animal off the line but no so much top end. Helping off the line power isnt the concern here, the top end is. The sooner you can get the manifold to start doing it's job the better off you will be. Add an underdrive crank pulley to your list of things to do. I bought it but havent installed it yet. From what i understand they make quite a bit of difference. I ported my kegger and it really wasnt that bad. I bought an extra so i had no down time and just went to town on it. Tanked it, sand blasted it, cut the divider out, cut the intake runers down, smoothed everything out, blasted it again, blew it all out with air, put it in the dishwasher lol. Wanted to make sure ALL the media was out of the runners. Probably spent 10-12 hours doing it. It's free horsepower im not worried about the time plus you can say you did it. IF anyone does decide to port the kegger it's more than just runners and a ported kegger on a 5.2 is not the same as on a 5.9 Anyone interested in learing about it or has questions can feel free to PM me. Anyway here are a few links for you

http://www.hughesengines.com/Index/...bnRha2VzICYgQ29sZCBBaXIgS2l0cyk=&partid=24773

http://cgi.ebay.com/ebaymotors/MOPA...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Only use the crank pulley and do whatever with the alternator pulley. Using the alternator pulley CAN cause charging problems. Not saying it will but why take the chance for the 1 ish HP gain you get out of it. According to what i have read, the crank pulley is good for 10 HP and 25 FT lbs. Worth the $65 any day all day. Maybe someone who has already installed them can add a little more about them. I duno when ill get around to installing mine. New damper is going on at the same time.

Here are a few pix of the manifold.
 

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#13 ·
Nice job with the kegger! Looks good and I'm sure it performs well. I hand ported a set of cylinder heads for my old Ford years ago when I rebuilt the motor and I spent in excess of 20 hours behind a die grinder on those. Worth the payoff, but a lot of work. This was before Edelbrock and others offered aluminum heads for that particular engine.

Again, at the risk of sounding defensive on Kolak's behalf, he NEVER recommended the M1 on a stock motor. He gave me pretty much the entire list of mods you guys have mentioned (including the UD crank pulley) and said that the M1 would be the next step AFTER all those are done. Well, I got all those mods and I was looking for the next step. Since I'm not ready to delve into the heads/cam territory, I figured this was the next step.

To be honest, I didn't even know about the Hughes/Edelbrock offering. The main difference I see is that the Hughes is a high-rise dual-plane while the M1 is a single-plane. This would definitely support your theory of the Hughes having a slight edge at lower RPM's. However, I will remind you that the Hughes is just an Edelbrock Performer RPM Air-Gap manifold with a throttle body adapter bolted to it (and some extra bolt holes). These manifolds were not designed for low-RPM operation, either. Bottom line, IF i had known about the Hughes manifold, I MIGHT have gone for it. My decision would have been harder, let's put it that way. One other thought I will leave you with on this subject is that dual-plane manifolds are generally NOT recommended for port-injected motors. You want as even of air distribution as you can get with a port-injected motor and dual-plane manifolds, BY DESIGN, do not offer very even distribution.

Now, I might wind up getting the UD pulley now that you guys mention it. My only fear is (as I'm sure it is with about anyone who gets UD pulleys) is accessory performance suffering. I recently fried my alternator that took my Optima RedTop with it and replaced it with a 200-amp unit and a YellowTop. I have a VERY healthy sound system in it and I'm just afraid the UD crank pulley would overstress my alternator. I'm sure the A/C compressor would be fine, but I also have my doubts about the P/S pump. I dunno. Anyone have any experience here? I'd sure like to pick up the easy ponies by bolting that $50 pulley on, but I'm not sure I wanna do it if it's gonna create a whole bunch of problems on the accessory drive.
 
#14 ·
I had the M1 on my 5.9 as well. I also had the Holley TB, Leach headers, K&N FIPK, and Mopar ECU. If you really want to take advantage of the M1, and the 5.9 really, get a set of heads. I think the Edelbrock heads are a close copy of the Mopar aluminum ones and are a good price.

I miss my 5.9 :(
 
#15 ·
I had the M1 on my 5.9 as well. I also had the Holley TB, Leach headers, K&N FIPK, and Mopar ECU. If you really want to take advantage of the M1, and the 5.9 really, get a set of heads. I think the Edelbrock heads are a close copy of the Mopar aluminum ones and are a good price.

I miss my 5.9 :(
I'm pretty confident the Mopar aluminum heads ARE the Eddy heads, just with different badging and subsequently, pricetag. I believe the main reason for the Mopar heads is if you're doing some class racing that requires OEM-based parts...or just have money to burn.
 
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