Tips for Getting More Power from a Chrysler 318 (5.2 L) V8

Nov. 01, 2005 By ORC STAFF
Edited by Donatas Lapinskas

Some time ago, I asked the participants of the Dodge message board for suggestions on how to get better performance (good low end torque and reasonable power) from a pre-Magnum 318 V8.

    Below are excerpts from the discussion that followed:

  • wrote:
    I'm doing some planning for my engine, and could use some advice:

    Option 1: New heads and cam for my 318. Direct Connection used to sell W2 heads which made these engines perform much better. Anybody out there know if MoPar Performance sells something similar now? Anybody want to recommend heads and a cam?

    Option 2: Drop in a 360 short block with appropriate MoPar Performance heads & a cam; keep my Performer Manifold, carb, headers, etc. Swap the driver's side mount & the torque converter.

    Option 3: MoPar Performance Magnum Crate Motor. Dunno what's involved here, but engine alone costs about $2500 discounted.

    Anyone care to comment/advise?

  • Mike in Alaska wrote:
    No No No No No! All those other posts are all wrong!!! (Just kidding!)
    Forget about W2 heads, they are for all-out racing. Way back in April 1988 Hot Rod did an article called 318 street recipes and built up quite the impressive small block. To make a long story short the results were: 331hp 9:1 comp. .455" lift cam. 1 5/8" headers. 750cfm carb. This may be an old part number, but the cam was P4286671. Heads: P4452748 - fully ported and complete w/valves and springs. Keep your intake and carb. You may opt for a slightly smaller cam. This is a good route if you want to save bux. Otherwise get the crate 360!

  • Kirk wrote:
    With all due respect, I thought we were talking about low end torque, climbing steep grades, and decent gas mileage. Ididn`t realize that you were talking about a street machine. The above STREET RECIPE should per form well in a 4500 lb. truck. 331 H.P. 455 lift , 750 C.F.M. Now wer`e talking gas mileage! Dont forget the 2, 000 stall converter.

    Honest, I`m not trying to be sarcastic, I`m just trying to get your attention!!! Over camming and over carbing, and just plain over building, has been more frustating to more people than you can imagine. If your`e going to try to build that 318, do yourself a favor

    1) Figure out just what it is that you want from this engine, what R.P.M.range you want to operate in.

    2) Call Edelbrock, or a professional engine builder, and get their advice.

    There is a Big difference betwen a street engine and a torque motor.

  • Mike in Alaska responded:
    I couldn't agree with you more. The guys that make a living on whether your engine works in YOUR rig is the place to verify any ideas that you are thinking of using (the local machine shop). The article used a 750 cfm carb, which is too big for a torquer motor and bad on gas. That's why I said stick with the carb and intake you have. I'm assuming a few things, like a 600 or 650 vacuum secondaries carb and a dual plane intake, of which the Performer you have is. A .455" lift cam is not at all radical. I'm basing this on the fact that the stock cam in a 318 has .400 lift, a 360 has .410 lift and the Performer cam from the excellent folks at Edelbrock has a lift of .420" and duration @.050 of .204 The cam from Mopar has been superceded by P4452761 and has about the same duration as the cam from Edelbrock, w/.450/.455 lift Intake/Exaust, meaning (I'm generalizing here) a similar powerband w/more hp throughout. The old 300 horse Commando 360 from Mopar Perf. had a cam w/.474" of lift. A cam that is large for a 318 is just right for a 360 due to the cubic inch difference. The heads from Mopar were ported for velocity and NOT just to "hog them out", meaning better response and power throughout the rpm band. The swirl design in the heads also adds to more power and a reduction in detonation. This means you can run more compression and more timing advance, giving you an all-around performer. Kirk is right. Call Edelbrock, Mopar Perf., Comp Cams(they have a website that you can get some numbers from), etc.

  • Kirk wrote:
    Thanks for the positive response, and clearing up a few things. I still have reservations on the cam. Using a PAW catalog as my reference, which has every popular cam listed, shows the followingfor the Mopar Perf. cam you refer to: No. MPP- P4452761- Factory engineered hyd. cam and tappet package for light competition. Offers good Mid-Range torque and power. 268-272-50 deg. Valve lift .450/.455. Centerline 110 deg.

    While I believe the description of 268-272-50 Deg. is wrong. Using a figure of multiplying .085 by 268, I still arrive at 227 Deg. duration. This still puts this cam in an operating range of 2500 to 6000 R.P.M. The description in the catolog may be all wrong, therefore I may be all wrong. However in a seperate chart they show this cam as being best suited to a 14 sec. bracket racer. One thing I have noticed in looking at a variety of cams in this catalog is that cams designed for small block Mopars tend to have lower lifts than that of ,say Chevy. While lifts for Chevy may reach 450" at around 212 deg. dur., Mopar cams won't reach that lift until around 225 deg. dur.. I have no idea why, but I intend to find out. If you have any info on this or more info on this cam, please let me know. Or if I`m just completly crazy, let me know.

  • LJ wrote:
    Finding a good set of 360 heads with an RV-type cam would probably work wonders with a small 4bbl. I've towed my car hauler with mine just stock and its ok, but it doesn't set the world on fire. We're gonna go with the new 318 heads from Aero ($349/pair) that includes valves, seals, springs etc. ready to bolt on. They also have 360 heads for a little more cash. Plan on using the RV-type cam from MP and a Performer intake/carb. For a parts chaser, we're looking for mileage yet be able to tow the car a couple times/year.

  • Clay wrote:
    Option 2 sounds good to me. I've heard that the 'J' heads are good flowing heads . Comp Cam 268H or Lunati Bracket Master II cam should work good with your Performer manifold and headers. IMHO, I wouldn't go over 230 degrees @.050 for a cam in a Ramcharger, they're too heavy . Cams that start making power above 2500 rpms aren't very good in heavy cars because getting a 5500 lb. vehicle to take off takes alot of torque (unless it's geared REAL steep ). A cam that starts making power off idle to 3500 rpms would be good for a daily driver. But, if you spend most of your time above 3500-4000rpms, get a bigger cam that's made to operate in those rpms. Does this make sense?

  • Mike in Alaska wrote:
    I know you are all hot to get that motor beefed up, but if you put new heads on an old '83 block without rebuilding it, the rings won't take the extra power. I know you put headers and a manifold on, and this is fine, but cyl heads (even a valve job) will probably be too much pressure for that tired block unless it has been rebuilt lately. You don't necessarily need to go with expensive parts, just freshen the thing up... piston + rings, bearings, grind crank, and definitely get the rotating assembly balanced. Save your money and spend it on doing things right the first time, you'll be glad you did.

    Go to the parts counter at the local Dodge dealer and for about 5 bux get the latest catalog from Mopar Performance. This book also has the tech hotline (1-810-853-7290). These guys have a paycheck that rides on you getting the best info on hi-perf mopar stuff.

    W/axles, I'd look into the feasibility of putting in an overdrive transmission first. Then you can utilize much steeper gears without hurting gas mileage too much. Make sure whatever you do w/axles, that what you put in has BIG brakes... tall tires (even 31's) are hard to stop when brakes get wet, muddy, etc.

    Try and do as much work yourself and put the cash into parts, not labor. I know it is hard if you don't have access to a garage, but do what you can. This way you also learn what to do and can fix stuff when things go bad off-road.

  • Terrence wrote:
    As I've recently worked through similar questions, I thought you might be interested in what I'm doing. I started with a compression test. I believe performance enhancements cannot make up for poor compression or a tired engine. My engine has 80K miles on it. The compression was okay, but indicated the need for a valve job. I would rather put my effort into improving traction, tires, suspension, diffs---things that let you better use the torque you have--but since I'm in for pulling the heads anyway, I wondered what was pracical to improve engine performance. I decided to model the Lil'Red Express: dual snorkel air intake; TQ 850 CFM; police intake manifold; heads and cam from '68 340; and a free flowing exhaust system.

    The key is the heads (valves 2.02i/1.6e). My options: get the heads off a '68-'71 340 (none local; aftermarket heads of similar spec; machine a set of "J" heads to take the larger intake valve; keep my exisiting "J" heads (1.88i/1.6e) and compensate with the cam. The last is what I chose because it's practical and fits my budget.

    Cam selection used to be easier. You bought Isky or Crane from your local speed shop. It still can be--I called up the local shop and relied on Joe (who coincidentally had been working on his girlfriend's RC). He asked about the truck, how I drive and what I was going for. Joe went through the catalogs and said he would use a Crane Max Velocity. He liked it because it was a newer computer modeled design, had high lift/higher on the exhaust, and a power band from 2000-4500.

    I then did some comparisons:

    Cams for LA Series              Lift         Dur       Dur@.50
    Stock Dodge/2bbl .410/.410 252/252
    Summit K6900 .420/.442 262/272 204/214
    Edelbrock Performer Plus .420/.420 270/270 204/204
    Stock Dodge/4bbl .430/.444 268/276
    Summit K6901 .441/.441 276/286 218/228
    Lil' Red Express .444/.453 276/284
    Edelbrock Torker Plus .447/.450 306/316 272/232
    Crane Max Velocity .454/.480 272/284 216/228
    Edelbrock RPM .488/.510 308/318 234/244

    Somewhere I read that for low end torque you want short duration and high lift, and that the problem (at the low end) in getting the air/fuel mixture in, is getting the exhaust out. Comparing against the listed cams and especially the 'Express, the Crane made sense. I then calculated what a power band of 2000-4500 means in MPH with 31" tires and 3.55 gears in low range.

    Gear/RPM     2000     4500
    first 4 9
    second 8 18
    third 5 33
    fourth 26 52

    I can drive with that, so I bought the Crane kit for $155. I believeit will let me obtain performance comparable to the Lil' Red Express.

  • I had a few questions to Terrence:
    1) Are you starting with a 318?

    2) Has your cam selection been influenced by manifold selection? Do you actually have the Lil' Red Express police interceptor manifold?

    3) What are your exhaust plans? I've invested about $425 in headers and a custom dual exhaust (but still no crossover pipe).

  • Terrence wrote:
    My starting point is a 2bbl 360. It already had headers--old style, no cross over, dual exhaust that exits in front of the rear tires. I've not found a police manifold locally so I got a regular one off an '83 and will use a 3/4" phenolic spacer to make up the height. The spacer has the added appeal of helping on hot days. On top goes a Thermoquad. The Crane cam was designed to work with the stock manifold and heads. If I were using ones radically different the cam choice would change--but then I'm moving away from low end torque and into high end performance. I expect to end up with around 300lbs of torque--but with a broad curve.

    What would I do different if my starting point were a 2bbl 318 that only needed a valve job? Not much. Back in the late '60's that engine powered a very overloaded full size van 150K+ miles without fail. I have a lot of respect for 318's (and torqueflites). According to Chilton's, in 1971 you could get a stock 318 that made 318lbs of torque! Anyway, I would expect my existing heads to have 1.78i/1.5e valves, and a cam of .373/.400 lift and 240/248 duration. My head options would include moving up to the stock 360 heads. I would probably go for that as they are reasonably priced ($75 each max) and I could have the rebuilt heads ready to go on as the old came off--thus keeping my wife's car from sitting out in the cold an extra night :) Cam choice would probably be the same (note that the 318 4bbl & 360 4bbl use the same stock cam) but I would rely on Joe's opinion.

  • Kirk wrote:
    I have been wanting to do the same thing for a long time, but since I`m in Calif. I have to be a lot more careful about what I can sneak by the law. But heres some of what I`ve learned. My primary desire is to create more low end torque without sacrifcing mileage. I managed to find a set of recently rebuilt 596 heads. these are supposedly pretty good 360 swirl port heads. Then I called Edlebrock to get there opinion on intake and cam for my 82 , 318. the first thing they said was " DO NOT PUT 360 HEADS ON THAT 318 ". It seems that the runners in any 360 head is to large to create good low end flow in stock or semi stock 318. In addition the runners in their performer manifold, are designed are of a low area design to help inhance low end flow. Isuggest you give them a call before spending bucks on a set of heads you might not want to use, like I did. Your`e best bet may be to just port and rough polish your 318 heads and gasket match them to your performer. Another thing to look at might be a split duration cam of 204 / 214 deg. @ .050 lift. this would give you the benifit of low end torque and some added power thru mid R.P.M.. One cam that looks very interesting to me is made by company called Hughes Cams. I understand that this cam is designed for Mopar, and is not simply an offshoot of some chevy cam. It has faster lift rates . Kick this idea around and let me know what you do. Good luck.

  • Charger wrote:
    Call mopar parts or look in a Summit Racing catalogue, or one like it, for the Mopar crate motor. They got a 360 that makes 380hp and 400 lbft of torque, out of the box. It stickers at $3500, but if you're a Chrysler employee, you can get it for around $2500. I think this is what LJ is talking about, maybe not. Mopar also makes a 300hp, and maybe others.


    This page last modified 27 Jun 98

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