Hello everyone,

As many of you know, I just finished replacing the frame on my Dakota. There are two main things left to do. 1st, the interior needs to be redone, and then, the v6 needs to be swapped with a 318. I was thinking about what I need to do to get more power out of the 318. I would probably like to do a full rebuild on it, so maybe a stroker motor...with better heads and Megasquirt engine management? Any ideas would be appreciated.

edit: I'm not sure I need a stroker to reach 300 hp. Maybe just a full rebuild along with better heads, cams, headers, and then smaller stuff like 180 degree thermostat...etc. Some of you guys may suggest a 360 swap, but I don't think I need that. I want more power, but I do not want to destroy my AX-15 (and lots of people are running with more than 300hp on these trannys, or the nv3500s). I already have the 318, and in my eyes it doesn't appear too much different of a procedure/cost to squeeze ~300hp out of a 360, vs a 318. A rebuilt and mildly "built" 318 is just what I think I need.

The Mopar Performance computer is another option for engine management; certainly easier than Megasquirt.

I am a total noob at this. I only have experience working on Subaru motors and I've only torn those down as far as the block; I've never split a block in my life! Much to learn, even though the machine shop will probably be doing a bunch of the work.

 

Tbug,


Have you seen this site? http://www.magnumswap.com/ The one pointer I would try is using a thinner head gasket. To get 300 hp, I would think you will need a cam and some head work at the very least. If these dodge motors are anything like a chevy, shortie headers are almost useless as far as power goes, and I don't think anyone makes a long tube header for a 4wd v8 Dakota.
Good luck, and I look forward to watching your build!!

 

well as to get power im not sure.. but in regards to the transmission, HP isnt the issue for the AX-15 its the torque , and its rated at around 400ft/lbs so it should handle fine. i have one in my JEEP TJ so i learnt alot about it since im looking at swapping in a 5.2 into this thing since engine is getting tired (300k)

 

Quote:

Originally Posted by 92DakotaClub

HP isnt the issue for the AX-15 its the torque , and its rated at around 400ft/lbs so it should handle fine. (300k)

Not doubting what you are saying, but could you tell me where you got that information? I have looked for torque ratings on the AX-15, NV2500 and the NV3500 and cant find it anywhere.

 

I wanted to add, again no experience in this, just what ive read, but the factory heads crack. If yours are damaged, Clearwater is supposed to be better then factory and they are cheap. Here is a link to some of them now. http://www.ebay.com/itm/2-NEW-DODGE-JEEP-MAGNUM-MOPAR-DURANGO-5-2-5-9-OHV-318-360-CYLINDER-HEADS-92-04-/171027563637?pt=Motors_Car_Truck_Parts_Accessories&hash=item27d2098475&vxp=mtr

 

Thanks guys!

I was planning on some head work/new heads, especially when I read about the cracking issues. The heads 93 ragtop linked above look quite promising and it's very likely that I'll go with those. If they're better than stock, that's not a bad price. Edelbrocks would be nice, but I'm not paying $800 per head. Yikes. I do like the idea of thinner head gaskets to up compression, versus milling heads.

I'd like to try out a mild cam, nothing extreme. Maybe a Comp Cams 260h or similar.

As far as headers go, I wasn't really hoping for a ton of power increase, but I need new ones because the ones on my 318 were cut. So if I can find stock replacements, that would be just fine.

As far as I know, Aisin never published torque specs for the AX-15, though people generally say that it is about as strong as a NV3500, which is rated at 310ft. lbs., as seen here:

http://www.allpar.com/mopar/transmissions/NV3500.html

Of course that's almost certainly a very conservative rating. No idea about the NV2500 capacity.

 

Just to add, the 300 HP benchmark is more of just applying a number to a vague goal. Basically I want to have a reliable motor with good street ability and decent power. In the end, I guess I'm more concerned with keeping good torque down low and not moving it too high up the range. I would also like to get into megasquirt eventually but it would be nice if the motor would run on the stock PCM. Not absolutely necessary though.

To summarize...300 ish...and a big ish at that.

 

The Clearwater / Odessa heads are the ones you want to get. The stock heads tend to crack and the Clearwater / Odessa heads are thicker in the cracking prone areas and are much less susceptible to cracking.

What kind of intake do you think you'll go with?

There is a cam in the user classifieds for a good price, check it out. I would pick out my cam and then call Clearwater / Odessa and give them the cam specs. They'll install the proper springs on the heads for you.

 

Tbug, I know you said you want to stay with the 318, but have you considered picking up a used shortblock 360 and rebuilding it? I see a lot of 360 engines on craigslist for 400-500 range. My experience is mainly with chevy motors, but the priniciple is the same. For a street motor, cubic inches wins out. To build the 360 vs the 318 runs about the same, so purchasing a used 360 shortblock would be the only additional expense. IMO it should have more low end torque and for the 400-500 layout its going to be a good buy performance wise.

 

jeep forums , lol since i own a TJ ive been doign alot of research on transmissions... ran across it one day now this is in regards to installign in a light jeep TJ chassis, now in a bigger truck , its torque spec might be lower to the 300 mark with the extra weight ..

basically the ax15 is a 3 speed for the most part since first is bull low(cant get through an intersection without shifting) i usually in second for take off and i run 35's on my jeep, and 5th is an overdrive and i never use it, cause of the 35's lol ..


and for more reference the Jeep 4.0 Stroker = 4.9L is pushing the 300-315hp mark.. and runnign the AX15........ also seem aftermarket support for building a AX15 is more available then the NV's ... dunno might be bias since i havent looke dmuch for New Venture in a while(my 91 Kota build is on hold , might even use the dana 60/70 i got for the dakota to overkill the jeep! and make the Dakota my Daily... LOL )

HP Forged Stroker kit for a 4.0 making it a 4.9L. Kit comes with SCAT forged 43/40 H Series rods, RaceTec custom race pistons, Total Seal or equivalent rings, Clevlite Rods & Mains. Kit includes custom blueprinted 4.00 stroke crankshaft. The kit is balanced and the compression is 9.2:1. This kit also comes with a Stage 3 cam kit and a double roller chain. Please allow 3 weeks for custom pistons to be made. Rated at 325hp and 400ftlb torque.Price does not include freight.

remeber im a jeep guy now, all i want to do is swap in a v8, did the research and for a jeep it can handle more due to its weight/size/16 inch driveshaft..lol anyway for the AX15 in a truck its more down to about 300HP MAX. and 320lbs torque due to the extra weight it has to move, anyway i have the AX-15 and its gonna be in my jeep this summer with a 5.2 magnum in front of it...


the NV2500 is garbage.... its actually downgrade to a AX15 .... the 3500 is about 20% stronger and good for 400 or so on the truck and the 3550 added 6th gear if i remeber correctly and was used in jeeps aswell in later years of 2000 and up or so...