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View Full Version : need 91 Dakota 318 build suggestions



MoparN75
12-23-2006, 09:24 PM
Looking for ideas on how to get some much needed power out of the engine. I'd like to stay with factory elec. and tb. Anyone with experiencial knowledge in this area? I know there's at least one cause I read this thread on dodgedakotas.com "Need info on 91 5.2". Appreciate any help you guys can offer.

turbovanmanČ
12-23-2006, 09:31 PM
Is it TBI or MPI, can't remember?

Eitherway, I would raise the comp a bit, from memory, there pretty low. Heads, either bolt on the Magnum ones or have yours ported a bit, use a nice RV cam, shorty headers, 3 inch exhaust, TB spacer if TBI and a chip if available.

MoparN75
12-23-2006, 09:41 PM
It's tbi. I actually have a couple 340 blocks in the basement, I'd like to build one of those. The greatest hurdle I can think of right now is fuel with either modified 318 or a 340. Don't know where to find info on the limit to the tb injectors. Oh yeah it's got to pass state emissions testing.

Millerman340
12-23-2006, 10:01 PM
Use a tbi off a 360 for flow but make sure that you swap back to the 318 injectors. the 92 Dak manifolds are the best flowing of the cast iron ones & have 2.50" outlets they went to 2.25" the next year. You can use a Aftermarket cam from Crane that's made for the computer controlled engine & it's a hydraulic roller.

turbovanmanČ
12-23-2006, 10:04 PM
340 won't work unless you remove the factory TBI and go something else, you'll never get it to run right and get it enough fuel.

Yeah, just stick with a mild computer RV grind, that way the MAP sensor won't go nuts.

MoparN75
12-23-2006, 10:28 PM
Use a tbi off a 360 for flow but make sure that you swap back to the 318 injectors. the 92 Dak manifolds are the best flowing of the cast iron ones & have 2.50" outlets they went to 2.25" the next year. You can use a Aftermarket cam from Crane that's made for the computer controlled engine & it's a hydraulic roller.

I'm incorrect in my assumption that 91 was the last LA version {tbi} and that 92 was the first magnum {mpi}?

turbovanmanČ
12-23-2006, 11:02 PM
I'm incorrect in my assumption that 91 was the last LA version {tbi} and that 92 was the first magnum {mpi}?

He means use the 360 TBI throttle body but your injectors and if you want to use stock type exhaust manifolds, the 92 is your best year. ;)

MoparN75
12-24-2006, 12:58 AM
Oh, okay, gotcha. How much of an increase do you suppose that would net?

Millerman340
12-24-2006, 07:43 AM
The stock computer is touchy. It wants to see what it was set for ,low vacuum drives it nuts so no big cams! Anything to help flow from the air cleaner to the tip of the exaust will help some. After battling this I went to a carb .

MoparN75
12-24-2006, 10:12 AM
Simply disconnect the injector wiring, but still using the computer or standalone and what carb?
Do you have emissions testing down there?

moparman76_69
12-25-2006, 02:42 AM
you'll have to keep the injection for emissions regulations. The first magnums didn't appear until 94 the first year of the new body style ram. You should be able to find shorty headers for it and then the crane cam suggested eariler and a chip for the computer. Upgrading to headers and a dual exhaust with crossover should open it up quite a bit. Then i'd do the chip. You need to increase airflow in other parts of the engine before you'd see real benefit from a cam.

Millerman340
12-25-2006, 09:18 AM
The Magnum came out in 92. chips are hard to find, If you have a source let me know as we have a Shelby Dak also that could use one.

22mopar
12-25-2006, 11:09 AM
actually the 1992 magnum 5.2 made the most power.

I've built a few of these trucks. the best small block was a 340, Dart heads, Offenhauser intake with 3 weber 2bbl carbs, Mallory billet distributor and ignition system, MP roller cam, roller rockers. generated right in the 450hp range on 93 pump gas.

moparman76_69
12-25-2006, 12:56 PM
340s were good for hp but were replaced by the 360 because 360s made loads better tq.


The Magnum came out in 92

oops guess i don't know everything dodge after all :rolleyes:

Millerman340
12-25-2006, 01:14 PM
340s were good for hp but were replaced by the 360 because 360s made loads better tq.



oops guess i don't know everything dodge after all :rolleyes:

That's ok grasshopper,;)

turbovanmanČ
12-25-2006, 03:17 PM
340s were good for hp but were replaced by the 360 because 360s made loads better tq.



oops guess i don't know everything dodge after all :rolleyes:

Yeah, a well built 360 can make gobs of torque and down low, a 340 needs to spin, not very practical for a DD.

BTW, my built 360 with real X-heads, nothing exotic on board, 91 octane layed down 415 ft/lbs at the rear wheels, not sure on HP as his dyno stopped at 250 if memory serves. This was a few years ago.

Millerman340
12-25-2006, 03:53 PM
My current 360 build is being done the hard way. 4.125 bore x3.375

turbovanmanČ
12-25-2006, 04:37 PM
My current 360 build is being done the hard way. 4.125 bore x3.375

Its been awhile since I have seen the bore and stroke of a SBD, whats that mean?

Millerman340
12-25-2006, 04:40 PM
stock 360 is 4.00 x 3.58 stroke

turbovanmanČ
12-25-2006, 05:08 PM
340 with a 318 crank?

Millerman340
12-25-2006, 05:19 PM
Siamese bore R3 48* mopar block with a La enterprises Kryptonite crank

turbovanmanČ
12-25-2006, 07:19 PM
Very sick and very nice, :thumb:

Millerman340
12-25-2006, 08:14 PM
Just wait until it has twin turbos! it's going in my 70 Challenger Vert.:nod:

Aries_Turbo
12-25-2006, 11:41 PM
engine masters just did a 318 build on the cheap. stock jy 360 older heads (pre magnum) with 2.02 intake valves and minor bowl porting (like super minor... just a little cleanup around the seat), cam (but kept the rest of the stock valvetrain), KB flat top replacement pistons, thermoquad 850 carb, stock rods with aftermarket bolts, stock 273 jy steel crank, and made 400hp and revved to 6500rpms. they swapped to a demon carb just for ease and speed in tuning on the dyno (time crunch) and made 415hp. pretty good for mostly stock parts.

you would have to ditch the efi though or somehow get someone to dissable the rom and make a table file for it so that you could edit it.

Brian

ShelbyMotorsports
12-26-2006, 02:01 PM
I'm incorrect in my assumption that 91 was the last LA version {tbi} and that 92 was the first magnum {mpi}?

The Magnum engines came out in:

1992
5.2 V8 & 3.9 V6

1993
5.9 V8

Your 1991 engine is exactly the same as any 318 TBI truck engine from 1988-91.

Crane makes a cam for it. Headers will fit with a little tweaking. And the tbi 360 intake/throttle body bolt right on.

Being a truck engine these things run out of oommph pretty quick so anything you can do to get the air in & out faster will wake them up until you reach the throttle body limits.

BadAssPerformance
12-26-2006, 06:40 PM
+1 on the '92 318 Magnum being a good motor... 192k miles and counting and 14.70's in the 1/4 ;)

http://badassperformance.com/mrides/dakota/dakota-rt2.jpg

MoparN75
12-26-2006, 10:02 PM
Let me ask this then,
Is it practical to convert tbi to mpi,...complete swap LA to magnum with applicable elec...?
Cause from what I'm hearing here and what I've read elsewere it's like throwing good money into bad....comparitively speaking, and if a conversion is impractical I may just wait a year or two and buy another truck.
One other though, the emissions station has never looked under the hood of any of my vehicles.

Millerman340
12-26-2006, 10:08 PM
just swap a carb on & use a older electronic distributor ,brain. Also you have to change the alternator to the older type also that's not controlled by the computer. Its easier to find a 92 than buy & convert yours. Dave.

BadAssPerformance
12-26-2006, 10:56 PM
Converting would require swapping all the electronics and the top half of the motor. Yes, easier to find a '92. The one in the picture will be for sale soon when I get another '92 to replace it ;)

Emmisions test dont usually care what is under the hood as long as it passes the test. Here in IL they hav edecided to cut costs and are doing away with teh e-test on pre OBD-II (1996) vehicles. YAY!

Millerman340
12-26-2006, 11:04 PM
and lets not forget that pesky crank sensor & ring

BadAssPerformance
12-26-2006, 11:07 PM
and lets not forget that pesky crank sensor & ring

yep, aalllll the electronics need to get swapped. Is the A518 trans the same '91-'92 in the Dakotas?

turbovanmanČ
12-27-2006, 05:08 AM
and lets not forget that pesky crank sensor & ring


Thats just the flex plate so no biggie on that.



yep, aalllll the electronics need to get swapped. Is the A518 trans the same '91-'92 in the Dakotas?

Some are electronic and some are regular, I think 91 is the last year for regular. I have a 90 A518 in my big Van and use toggle switches for 4th gear and lockup.

BoostedL
12-27-2006, 10:31 AM
Chime in for a minute.

Just sold my 92 dakota with the 5.2 mag motor with 201k miles and ran like a champ.

In the unrestricted area, I have a 340 forged crank forsale which would bolt in to your 318 motor. They are the same stroke at 3.31.

Port your heads and if possible look into using the magnum heads. They are a big improvement over the older LA heads.

You should be able to get the fuel dialed in with all the above info. PM me if your interested. I think I have a spare set of mag heads also.

ShelbyMotorsports
12-27-2006, 02:12 PM
Port your heads and if possible look into using the magnum heads. They are a big improvement over the older LA heads.

Magnum heads on a pre-magnum motor takes some effort to work.

If I recall the Magnum heads bolt right on but you need Ford pushrods/lifters to get the oiling system to function. I also believe that the pre-magnum intake manifold wont bolt on to the Magnum heads so you are forced to go with a carb'd intake.

Best advice is if you really want a Magnum set up in a Dakota just purchase a 1992 or newer Dakota. The 1992-96 Dakotas aren't that expensive and the headaches you'll save yourself will be worth it especially since you want to stay smog legal.

Steve

BoostedL
12-27-2006, 02:26 PM
Off this thread and I believe I read the same info off the Mopar small block performance book...

http://www.moparmusclemagazine.com/techarticles/mopp_0510_edelbrock_magnum_heads/rockers.html

You can use mag heads as long as you use lifters that oil through the top and pushrods that oil through the center.

Since he was talking about hot-roding it to a degree. This would be my setup.

340 crank to pickup the forged aspect.
Forged pistons at .040 over or sonic test the block for a .060 bore.
Ported and polished magnum heads with 2.02 and 1.60 valves
Balance the whole thing and get it milled for a 9.5:1 CR.

Get the fuel and air to the motor via a dual plain intake for street use and still have some fun at the track.

Given an old motor...You would replace the lifters and pushrods anyways. And if you can get a set of mag heads and put some rockers on them, you should be somewhat set.

turbovanmanČ
12-27-2006, 02:44 PM
Thats a cool trick about using SBC rocker arms on Magnums, thats the first I have seen that, :nod:

But in all honesty, if he changes the heads, adds a nice computer cam, headers, you might be able to run a dual plane intake and retrofit your TBI on by making an adapter plate, you can easily get more power without taxing your stock computer.

ShelbyMotorsports
12-27-2006, 04:03 PM
Off this thread and I believe I read the same info off the Mopar small block performance book...

http://www.moparmusclemagazine.com/techarticles/mopp_0510_edelbrock_magnum_heads/rockers.html

You can use mag heads as long as you use lifters that oil through the top and pushrods that oil through the center.



But you missed this part of the article:

Aside from that, the Magnum valve covers and a Magnum-patterned intake will also be required.

As I suspected his 1991 intake will not bolt up to the magnum heads which means he is forced to use the Magnum barrell intake (which requires converting his trucks electronics) or an aftermarket carb'd intake that fits the magnum heads.

Even then he would still have smog inspection issues because of this converted engine.

BoostedL
12-27-2006, 04:39 PM
The valve covers I saw...Didn't look for the intake.

I built a LA 360 motor with Edelbrok heads and used a dual plane intake (edelbrock) and put a carb on it for my jeep. Not the same app at all but I knew the mag heads could be used because I researched it before I got my edel heads.

turbovanmanČ
12-27-2006, 04:44 PM
But you missed this part of the article:

Aside from that, the Magnum valve covers and a Magnum-patterned intake will also be required.

As I suspected his 1991 intake will not bolt up to the magnum heads which means he is forced to use the Magnum barrell intake (which requires converting his trucks electronics) or an aftermarket carb'd intake that fits the magnum heads.

Even then he would still have smog inspection issues because of this converted engine.


Just make a plate to adapt the TBI, like I said earlier, not that hard and infact, you can buy them due to propane conversions etc.

Why would he have smog issues, they don't look under the hood or inside the engine?

ShelbyMotorsports
12-27-2006, 08:35 PM
Why would he have smog issues, they don't look under the hood or inside the engine?

Most of the eastern states that now require smog testing basically just copied Californias program. Are you saying MD doesn't look under the hood when doing a smog check/inspection?

If so that's great to hear as I've always believed that smog tests should consist of only the tailpipe readings. By that I mean if the tailpipe readings are as clean or cleaner than factory stock readings you should pass no matter what you've done to the engine.

turbovanmanČ
12-27-2006, 09:42 PM
Most of the eastern states that now require smog testing basically just copied Californias program. Are you saying MD doesn't look under the hood when doing a smog check/inspection?

If so that's great to hear as I've always believed that smog tests should consist of only the tailpipe readings. By that I mean if the tailpipe readings are as clean or cleaner than factory stock readings you should pass no matter what you've done to the engine.

Yeah, he said earlier that they don't look under the hood, just tailpipe readings, :amen:

MoparN75
12-28-2006, 08:32 AM
That is correct....They use mirrors to look for leaks and to inspect exhaust system for muffler and cat {though they've never hassled me for no muffler, they have my wife}. Check fuel cap and then it's onto the tread mill while they sniff the exhaust. My turbo cars are always well below state standards. The Dakota we're referring to just barely pass last time. They test a vehicle every two yrs. Oh, and I believe OBD2 is only pugged in, no thread mill required.

ScottD
12-28-2006, 10:18 PM
Hey Stan,

Since I had an 89 Shelby Dakota for several years I ended up researching this exact topic and my conclusion was options for the 89-91 pre-magnum V8 were pretty limited. Now supposedly the heads on your 91 are pretty decent and respond well to some mild port work. The recipe I came up with for my Dakota was basically to mildly port the heads, mild cam, larger 360 throttle body, headers, and open up the exhaust, and I would think that would probably be a good recipe for yours as well. The 92-96 Magnum V8s in a Dakota are out there and pretty cheap at this point. I guess it really depends on what shape your Dakota is in and how much work you have into it already. Sometimes if you have work in a vehicle it is better to stick with it. Also, as far as emissions, my 90 Dakota almost failed last time (when the previous owner had it, the emissions report was in the records he gave me). Plugs wires cap rotor fuel filter and K&N later it passed with flying colors. And only to find out that during the test the speed sensor was dead. I put in a new speed sensor, 02 sensor, and fuel pump (at 193k I thought it was a good move) and it runs great now.

ShelbyMotorsports
12-28-2006, 11:25 PM
Yeah, he said earlier that they don't look under the hood, just tailpipe readings, :amen:


When he said "the emissions station has never looked under the hood of any of my vehicles" I took that as they are supposed to look but were just too lazy to do so. Just like when they used to go check the gas cap and find its a locking cap they just give the cap a pass instead of getting the key.

Now that its been clarified his state does tailpipe testing only I only wish California would do the same.

I still say purchase a 92 or newer Dakota and get the aftermarket support that the pre Magnums didn't.

turbovanmanČ
12-28-2006, 11:29 PM
When they first brought out our emission testing, they used to look under the hood, we argued what for, they don't know what there looking at. Finally, after a couple years, they dropped that and now just tailpipe, and a mirror check for the cat. :nod:

MoparN75
01-21-2007, 02:26 PM
Hey Stan,

Since I had an 89 Shelby Dakota for several years I ended up researching this exact topic and my conclusion was options for the 89-91 pre-magnum V8 were pretty limited. Now supposedly the heads on your 91 are pretty decent and respond well to some mild port work. The recipe I came up with for my Dakota was basically to mildly port the heads, mild cam, larger 360 throttle body, headers, and open up the exhaust, and I would think that would probably be a good recipe for yours as well. The 92-96 Magnum V8s in a Dakota are out there and pretty cheap at this point. I guess it really depends on what shape your Dakota is in and how much work you have into it already. Sometimes if you have work in a vehicle it is better to stick with it. Also, as far as emissions, my 90 Dakota almost failed last time (when the previous owner had it, the emissions report was in the records he gave me). Plugs wires cap rotor fuel filter and K&N later it passed with flying colors. And only to find out that during the test the speed sensor was dead. I put in a new speed sensor, 02 sensor, and fuel pump (at 193k I thought it was a good move) and it runs great now.

Scott,
Sorry I haven't gotten back with you. Haven't been on the board much lately. In your research did you find headers for the 2wd v8s. It looks like an a-body set would fit if I couldn't find anything else.
I've been tempted to get an R/T. Saw one for sale recently complete with supercharger, high 12 second truck with 60k on the clock for 8 grand. But I may just throw a paint job and motor at my 'paid-for truck'.

ScottD
01-21-2007, 02:51 PM
Headers are probably available. I just checked on headers for my 90 Dakota Sport 3.9 and Summit carried them, so I don't see why they wouldn't be available for the 5.2.

As far as the R/T trucks, they were limited in their tow rating because of the rear suspension. I think the tow ratings on them were pretty low. They are pretty cool trucks though. I personally like the 92-96 Dakotas the best, that is what I was looking for when I bought my Dakota (the lure of the convertible was too much) and eventually I'd like to get a 92-96 swb Sport.

MoparN75
01-21-2007, 03:05 PM
Yeah I've seen the headers for the 6cyl but never any for the 91 5.2. You getting any snow over there? Started about 1/2hr ago here.

turbovanmanČ
01-21-2007, 04:57 PM
I am sure I have seen headers kicking around. Tried Jegs, Summit, Ebay and I think even Mopar carried some.

ScottD
01-21-2007, 05:28 PM
No 5.2 headers, that's strange, I seem to remember them being available for my Shelby Dakota.

It has been snowing here for a bit, since the Bears are making a laugher of the game I think the dog and I are going to get out in it for a bit, and burn some of her energy off!

Millerman340
01-21-2007, 05:39 PM
http://motors.search.ebay.com/search/search.dll?sofocus=bs&sbrftog=1&from=R10&satitle=dakota+headers&sacat=6000%26catref%3DC6&fmmk=&fmmd=&fylo=&fyhi=&mppfqy=dakota+headers&sargn=-1%26saslc%3D2&sadis=200&fpos=ZIP%2FPostal&ftrt=1&ftrv=1&saprclo=&saprchi=&fsop=1%26fsoo%3D1&coaction=compare&copagenum=1&coentrypage=search

Dave_J
02-02-2007, 11:18 PM
The Magnum engine heads are a great starting point. The rocker ratio is 1.6:1 compaired to the pre 91's 1.5:1 so you get more lift with the same cam. I am building a Magnum headed 273 with a 360 crank that should be at the 370 HP range real soon. Here is an Amazon.com link to a Magnum building book http://www.amazon.com/Modify-Mopar-Magnum-V-8HP1473-Step/dp/1557884730/ref=pd_sim_b_5/103-3869239-3375011 . DaveJ