Dakota Exhaust

[Detective D]

I blew the gasket on my driver side manifold. The 5500rpm massive burnout(my son laughed for 5 minutes afterwards) may have contributed, but I mean, it coulda been anything

Anyway, I went under there to look at the pipes harder for the first time. I was planning on replacing the system despite being in decent shape anyway (50k miles on this truck) for some hot rod reasons. I figured JBA headers(shorty) because of the quality, but never thought much about the rest yet.

In case anyone is curious, my 98 5.2 magnum Dakota has a system similar to something you would expect out of a 1977 car. I was actually surprised. A Y pipe off the manifolds to a single pipe, one converter, a short pipe to one muffler, exit over the axle out the rear side single exit. Simple, old school. the only thing different is the O2 sensors compared to something 20 years older.
No mandrel bends. I think it is a 2" pipe.

Not kidding on the Y pipe, I think the 90 degree bend from the driver side pinches down to like maybe 1.5" OD. And it is full of those little creases. Wow.

I doubt anything is plugged up. I think that Y pipe is so restrictive the exhaust blew the gasket from back pressure from the completely inadequate pipes. I found this on Summit, it is probably an OEM style pipe it looks similar:

1998 DODGE DAKOTA Walker Exhaust 40235 Walker Direct-Fit Y-Pipes | Summit Racing

Free Shipping - Walker Direct-Fit Y-Pipes with qualifying orders of $109. Shop Exhaust Pipes, Y-Pipes at Summit Racing.

www.summitracing.com

Not exactly a performance part! Look at all the pinching!

My real question to the board here is:
For a mildly tuned up 318 magnum, is a 2.5" single, quality mandrel bent system with a low resist muffler(and possibly no cat) adequate flow for the engine? I plan an intake eventually, 1.7 rockers, the headers.
I can't find a true crossover pipe to bolt on, likely because the transfer case takes up a lot of important real estate under there. JBA makes a MUCH better y pipe, but description says 2.5" outlet. There are dual cat backs, but really if it is coming out of a Y it won't matter. I can go custom if need be, but I suspect that will run $800 vs a sub $300 stainless bolt on.
I will not do a cam or touch the heads on this truck, but the 1.7 rockers act about as much of a cam as the stock heads can handle anyway I am reading.

Some internet surfing this morning(I took a vacation day!) so looking for feedback for future plans here.

 

[YY1]

Look at a Dakota R/T exhaust.

IIRC it's a larger single Y pipe to accommodate the two give or take 2" manifold outlets.

I want to say mine is at least 2.5" and could be larger.

It's pretty cramped on the side without the pipe.

Mine has a cat back dual system which I believe is factory except for an upgraded low restriction muffler and chrome tips.

No headers on mine. I actually LOVE the unique and easily identifiable sound those Mag manifolds make. They flow pretty good, too.

You could look for the '92 manifolds that IIRC have 2 1/8 outlets vs the other years 1 7/8.

 

[Detective D]

Look at a Dakota R/T exhaust.

IIRC it's a larger single Y pipe to accommodate the two give or take 2" manifold outlets.

I want to say mine is at least 2.5" and could be larger.

It's pretty cramped on the side without the pipe.

Mine has a cat back dual system which I believe is factory except for an upgraded low restriction muffler and chrome tips.

No headers on mine. I actually LOVE the unique and easily identifiable sound those Mag manifolds make. They flow pretty good, too.

You could look for the '92 manifolds that IIRC have 2 1/8 outlets vs the other years 1 7/8.

This is what i am looking at(not from here possibly, there are some interesting one time sign up coupons at the box stores)

1998 DODGE DAKOTA JBA Performance Exhaust 2945SY JBA Performance Exhaust Y-Pipes | Summit Racing

Free Shipping - JBA Performance Exhaust Y-Pipes with qualifying orders of $109. Shop Exhaust Pipes, Y-Pipes at Summit Racing.

www.summitracing.com

Says 2.5 in, 2.5 out. The bends are obviously 1000% better. I am not sure if the y pipe is 2" with a 2.5 flared inlet or actually 2.5, but by looks it seems 2" into a 2.5 well designed collector.
Pretty sure the R/T did have a factory dual exit. I would probably stay at a single. Whatever the Y pipe collector is is going to be the overall pinch point in the system anyway. I am a fan of stainless Gibson truck mufflers, excellent flow and not Dronemaster or Magnabark blat sounding even at idle. Performance with quiet idle. Not exciting enough for a toy car, but this will be a commuter vehicle in the near future. I want it to be lively, responsive, and fun, but not attention grabbing loud, and max performance is not a goal.

I might go look for a factory style R/T y pipe just to see, might be less pricy.
Still wonder if 2.5" single is going to flow enough to make the 318 magnum happy after the other mild changes, but without a custom Y pipe, or something akin to cutting the collector off to run two pipes(no crossover, generally not my cup of tea) not sure I will find an alternative. For sure would be better than stock, I just like doing things once I guess, don;t want to do this and then find out the rockers upgrade wasn't worth it because the pipe is too small.

If this was a GM I would have 14 options lol. Oh well, Mopar or No Car, that's how it is! GM never made anything like a Dakota, nobody has.

 

[YY1]

I forgot mine also has a low restriction performance cat.

One is Dynomax, the other is Magnaflow.

I never remember which is which.

True duals is likely quite a challenge as the trans cross member is at an odd angle, there's other stuff in the way in that area, and even if you do mod that, you still don't gain much room.

The cat back dual setup is reasonably sound in theory, as the gas is expanding, so reducing the restriction anywhere down the line in the exit path should help.

 

[Detective D]

Well some more looking I came across Spintech. They make a 3" y pipe, and a true dual 3" system. But they both cost a fortune.
my truck is low miles and I want to keep it for a long time, but I paid $1000 for it. Spending 2 grand on a set of pipes does not seem logical to me lol.

I think for simplicity sake I will do the JBA header and y pipe. I might have to experiment with the rear O2 and see how picky the ECU is for the rest. I can probably piece together the rest of the system for a lot less than buying a kit, unless I fork over for a dual set up. I have some time for that yet. I think I am going to start collecting stuff and make a project of this in the winter months so I don't get bored in January. Might keep watch on facebook market for a little while too, but I doubt I will find anything besides maybe headers on there, not enough people building 90's magnum engines anymore, shame really the trucks are affordable.

 

[33 IMP]

If you can, check out engine masters test of single verses dual exhaust test. They pitted a single 3" with a really nice y-pipe against a dual 2.5 system


The single 3" won.

 

[Detective D]

If you can, check out engine masters test of single verses dual exhaust test. They pitted a single 3" with a really nice y-pipe against a dual 2.5 system


The single 3" won.

I found a lot of really OLD dakota forum posts(like 2005 lol) that went on about single 2, single 2.5, single 3, dual 2.5 and dual 3
The consensus was dual 3 was so big it destroyed all the scavenging. One guy lost 8hp on the dyno.
The other consensus was dual 3 was so loud people hated it. Single 2" is about as close to stock system as it gets, with the non-mandrel bends and crappy corners it takes.
lots of debate between 2.5 dual and single 3, most opinions were true dual no crossover lost power vs a 3 but a fab'd H pipe and they were about a wash. One guy fab'd up a h-pipe dual 2.25" and claimed perfection

What I am finding the more I look is a lot of products have fallen off the map for the late 90's dakotas. Still a good bit for the 4.7 crew cabs that sold all the way till the end, but the 90's 5.2 ex. cab trucks are getting limited. Summit has a factory china replacement, a pair of gibson dual exit in 2.5, and a Magnaflow(like 800 bucks!) dual exit. The magnaflow is a 3" single inlet with a dual outlet muffler. No singles listed anymore. I would actually prefer a 3" single for ease of instal and probably a good cost savings but I might have to have a muffler shop make the tail pipe, flowmaster had one but Holley doesn;t list it on their site anymore so I am guessing it is discontinued. Otherwise the aforementioned super expensive Spintech is there....

It is weird overall, you can buy the mufflers from these systems for like 80 bucks, and a stand alone(although smaller 2.5 inch) single tail pipe is like 100 bucks. But if you want a kit, (two tailpipes and the same muffler), now it costs 650 dollars minimum. I might make my own section for behind the Y pipe and have a muffler shop make a tailpipe for me. Probaly end up at 1/3 the cost of one of these kits. If I was younger or not going to drive this thing to work every day I might just do a little turndown elbow on the muffler like the old farm truck days, but I think it would drone too much on this truck. Maybe I will go look how bad an exit in front of the rear wheel would be.

 

[YY1]

I'm gonna circle back....

Good flow on Y pipe, cat, muff.....and cat back duals.

Reread what you just wrote that came from the Dakota forum, then reread what I just wrote.

 

[YY1]

....and also I'd seriously hold off on headers.

Do some serious "numbers" research to see if they are worth it.

...especially if you are still figuring out the exhaust from there back.

 

[Budnicks]

I have the stock headpipe/crossover on my 99 DakotaSLT 4x4 5.2ltr Magnum
it goes into the stock cat. 2.250" & then exit out with a 2.5"
into to a single 3" Delta 50 Flowmaster cat back muffler system,
it woke it up 'a bit'

I have Chrome 1-5/8" Edlelbrock truck shorty bolt-on headers ($400-ish)
(I got with Summit bucks, I had stored, up use it or lose it, so I got them)
for it, 'allegedly' will bolt directly to the head-pipes, I never put them on
according to my old head porter buddy
the Magnum Iron manifolds are supposed to be pretty good flowing
for iron manifolds
allegedly the best for all the SBMs

I have a Hyperteck tuner, I usually run 89 oct. it has the 91 oct tune, no detonation ever
needed it also for the tire size change 32"x11",
helped a lil' off idle at stop lights or lower throttle,
a bit better mileage, a lil' advance (not very much)
not as much as I thought it would

I have 1.7:1 HS rockers (this one thing woke it up the most) bolt-on,
Edited; w/same stock ball/ball 5/16" PushRods

I also have an AEM airbox w/gauze 9"x5" tapered filter/into 4" alum. intake tube
to their hat ontop of the TB, with a 1/2" swirl spacer under the stock TB

all of it helped a lil', IMO the Rockers,
you could literally feel it climb the steeper grades, come off the corners & have power
getting up the hills, way, way better 10% better/more lift
& the 3" cat back system, you could feel it pull harder too
those 2 was/were the most noticeable improvements

best mileage gain was the tuner, airbox/intake/filter & the exhaust
free'd it up to breath
when I added the rockers the milage didn't change much
if anything it got better, didn't have my foot planted in anywhere near as much
down on the flatlands it's a night & day different rig,
up here at elevation, it just helps

I have just over 60k on it now too

 

[YY1]

On the intake side, I have a K&N cone style intake and carb hat.

180,000 miles on mine.

There's been a LOT of R&D that says the Magnum manifolds are just as good as headers, or almost as good and nowhere near the maintenance and hassle.

 

[Detective D]

I'm gonna circle back....

Good flow on Y pipe, cat, muff.....and cat back duals.

Reread what you just wrote that came from the Dakota forum, then reread what I just wrote.

I will likely end up running a dual system. No one makes a 3" single, the one that was out there was 1/3 the cost of the dual set ups. Dakota forums consensus was between an h-pipe dual 2.5 and a single 3, it was a wash. I was looking for the less costly route to the same result, but unless I make my own there is really only one choice.

I don;t need to do emissions. So I could straight pipe the whole thing if it didn't get so loud to draw attention, it is likely the factory cat will go if only for the pipe size but time will tell. I know the cat itself is not really a constraint in modern day, but the crappy 2" inlet is.

headers are going to be decided on once I have the Y pipe in hand to evaluate. The JBA stuff has a 2.5" opening. I don;t need to drive this truck right away so I can afford to wait for parts and work on it a little at a time, I will probably decide once the Y pipe is in hand and I can see how it matches up with the stock manifolds. headers are a couple hundred bucks.

i worked on a 94 5.0 Mustang I owned for ten years. i think the 5.2 and Ford's 5.0 are similar in that they came choked from the factory. I ended up with the 5.0 in a similar way as my plan here, no touching the heads or a cam, just made it breath and got roughly a 40P gain and in that car got same MPG with 3.55 as factory 3.08 gears. In this dakota i will expect a 1 MPG increase, about 40HP, and a lot more responsiveness in driving characteristic.

I don;t want to short the end result by skimping on a couple hundred bucks, but I don't want to throw 2 grand after 4HP either.

I do like how this board is full of knowledgable people that can understand the difference between a daily driver street 318 and a stroked 440 that runs the 1/4. In chebby and Ford land, all the intenet mechanics escalate every power add discussion to the point "might as well replace the entire top end, do a cam, straight pipe 3" duals, run slicks, probably NOS or at least a blower, otherwise why bother". not right out the gate, but by page four of a thread it was all or nothing, every time. Got to where I just looked up specific things and ignored the "help". I like how people here offer experiance and know the parts so well. lets me trust opinions a lot more.

 

[YY1]

I think you missed my point.

Cat back duals is in the sweet spot between 3" single and 2-2.5" true duals.

...and a LOT less work.

That cat has been on my truck since before I bought it at 30K miles.
I've put another 150K on it. I don't think it will ever go bad.
(Of course I just triggered it to go bad today)

 

[dodgedifferent2]

Not sure if they would work, but hooker had long tube headers 5803, but they were geared to the 91 dakota.
Again I don't know your body style dakota and headers. I do know the 5803 are almost impossible to find now.
I planned to put the pair of 5803s i have on the 96 when I get the indy headed 340 stroker stuffed in this winter.

 

[YY1]

"Under the sheet metal" the Dakota didn't change very much until the 2005 and final body.

 

[Detective D]

Y pipe is on order from Summit. JBA makes the only worth while pipe out there without going custom. It is a 2" mandrel bent into a 2.5.
I tried to measure the stocker at the pinch in the bend on the driver side, will be taking it off this week I hope. At the pinch/bend, best I can tell(hard to fit my caliper) it is 1.6", possible smaller it was hard to fit the caliper up there straight. Imagine the entire driver side having to go through a pipe the size of most header primary tubes.

I did notice the JBA says auto's only. That is why I climbed under, the space between the front dirveshaft and the side of the bellhousing is going to be tight! I figure worst case scenario I can make a mini flat spot for clearance, and still have way more flow then the stocker. I don't think it will be an issue though, there is a little heat shield attached to the stock pipe there and still 1/4" of space on top of that. Just need to make sure it won't rub.

 

[Detective D]

Update:
JBA pipe is installed. There is a reason they say auto only. I got it in there anyway with some work.
Basically, the bellhousing must be bigger around then what the auto transmission is. What the pipe ends up doing is coming into contact on the very bottom of the bellhousing, and then the passenger side downpipe before the Y collector ends up being too short by the time you get things all pointed where they should be. I did two things:

I used a flap disc to remove the very front part of the bottom 3 ribs on the bell housing. Not into the actual bellhousing, just the three bottom most ribs. Started towards the front edge and hollowed out a sort of semi circle, this gained almost half an inch of space. There are additional ribs to the side of the bottom area, I am not concerned with strength at all after this modification.
I cut the downpipe on the passenger side, and got a band clamp designed to seal butt splices so I could extend that side about 3/4". The down pipe is straight there, so this was pretty straight forward.

With those changes, the outlet was approximately where the stocker was originally at the collector, but pointing uphill maybe 1 degree more.


I had the mid pipe out, knowing I would need to mess with it to get it back in once I found the pipe was going to need tweaks to get installed. The CAT had things clunking around in it. Not usually a good sign. I have it replaced right now with a section of straight pipe. I do not need emissions checks where I live, so if it doesn;t throw codes I might leave it. If so, I will buy an aftermarket high flow to put where the pipe is.
This was actually to my advantage(cutting the cat out that is) as it allowed me to rotate the mid pipe slightly to better align with the new angle on the y pipe. I gave the rear section(after cat, before muffler) about 1/8th a turn and everything lined up just fine, plenty of clearance. A few more clamps in there then what came factory though.


The Y pipe itself is not even in the same ballpark as the factory pipe. The bends are mandrel, and it is no comparison. My estimate of about 1.6" on the factory pipe was close, it came to 1.52 at the smallest point(OD!) The JBA is 2" ID, all the way through.
If you have a Dakota and have any reason to mess with the factory Y pipe, I highly recommend this JBA pipe. If you have an auto it should install very easy.