stock horsepower

[b123058]

Does anybody know how much a stock 318 makes?

[dave571]

I don't have that kind of info, but NOBODY here can answer that question without some year info, ect.(2 bbl/4 bbl?? ect)

I believe some were rated as high as 220 while others more like 160.

[DartGT66]

The "best" ones were rated at 230 hp, but the rating changed in '72 while the 318's did not. The new rating was 150 hp, which is closer to the truth. The old pre '72 hp numbers are more or less paper horses.

[b123058]

My 318 is in a 74 Scamp

[DartGT66]

It's propably in the 130-150 hp range.

[Dart 65]

The stock '74 318 made 150 horses, while the 318 that was the Road Runner base engine made 170. The best horsepower rating that the 318 achieved was 230, and that was from 1967-1971. After that, the number of horses rose and fell, but never got to be more than 160 after that point, even with the four barrel.

[DartGT66]

and what is most disturbing is, that the differently rated engines, except the four barrell, have practically no internal or external differencies that should affect the hp.

[thewrongguy]

out of curiosity do you think the numbers were under-rated for insurance companies, or over-rated for sales sheets.

I know the new turbo neon was rated at 230 hp (i think) at the crank and some rice magazine (it was in my dentist office of all places) had it make 227 or something at the wheels stock. I assume it's underrated so the kids they're trying to sell them too can afford the insurance (not like that poor pizza boy driving the beemer).

[71383bee]

There is little to no difference between the 72 and up 318's and the earlier pre 72 318's. There were some cam and compression differences, but the major drop in hp was due to Mopar switching from gross ratings measured at the crank in pre 1972 to net ratings measured with accessories and at the rear end. The rear end dyno hp is the actual hp of the vehicle. A 230 hp motor with accesories and running through a tranny and rear end would make 170 or so rear wheel hp.

When did they offer a 4Bbl 318? I didn't think Chrysler offered stock 4Bbl 318's.

[DodgeBoy318]

I read from a stock horsepower table on some website that the stock 2bbl 318 made 240hp, but thats kind of hard to believe seeing as how the chevy 350 makes 260hp. But geez 170?? That makes 318's sound like plugs. How do you think a single plane intake with a 600cfm 4bbl, 218/228 duration cam w/.441 lift and headers would improve it? Call it an....educated guess.

[71383bee]

I don't think you are understanding what I am saying. A stock 318 putting out 230 horsepower at the CRANK will output about about 170 horsepower at the rear wheels. The horsepower ratings never went down, they just changed where they took there ratings.

I have no clue about chevy ratings nor do I want to know....

Now admittedly the 72 and up 318's did output less than earlier 318's, but that was more due to lower compression and lower octane ratings. Remember regular in the late 60's and early 70's was around 91 octane. Premium was in the 105 range which is why the older engines could run on higher compression.

What year 318 are you talking and what other mods are done to the engine?

[dave571]

There was a stock 4 bbl 318. It was very late in the production run, I don't have the numbers handy but it did exist. I think it was in a truck.(I seem to remember seeing it in a book on mopar engines. I don't recall seeing one myself)

As for the change in ratings, I'm pretty sure it was Gross hp to net. Not crank to wheel.

Gross is without accesories.(as I understand it)

I personally doubt a 318 ever made more than 180hp at the crank, in stock form.(pre fi magnum engines)

[71383bee]

It must have been after 1974 because i have the shop manuals up to that time and i can not find anything in them about a 4Bbl 318.

I think you are right about the gross vs. net thing. The major point I am trying to make is that the motors themselves changed very little, it is just where they took the rating that changed. Besides factory rated horespower ratings are extremely ambiguous and not a good representation of what a car can really do. I have seen supposed 350hp 350 CI chevy's get spanked by 340 challengers or 383 B bodies and the factory rating for those were 275 and 330! So all this talk about factory ratings really doesn't amount to jack. Timeslips and dyno numbers tell a better tale of what the motor can do.

[Dart 65]

I have two 318s in my garage, one is from 1969, the other 1977. The '69 has the higher compression of 9.2:1. It has flattops with valve reliefs and a two barrel intake. The '77, however, has regular flattops and a four barrel intake with a Rochester carb no less. Otherwise, there are no differences, but 71383Bee already gave the reason for the differences in horsepower ratings. Yes, the compression ratios dropped, but the biggest "loss" of horsepower was the change from net to gross horsepower mandated by the government in 1972. That made the differences seem that much greater. Up to that point, the automotive companies rated their engines with no accessories at all; no water pump, alternator, or A/C. Another factor was the insurance, and I understand that at the time, any car with an engine possessing over 425 horses fell into a different bracket that was almost unaffordable, but I don't know this to be fact. I tend to believe it, though, because if you look at a stock 426 Hemi, it is very underrated at a mere 425 horses. Factory engineers have said that it was putting out closer to 500. But back the 318s. Another factor may be that the factory put thicker head gaskets on the later smogger motors. I hope all of this helps.

[Mills]

As Dart 65 said concerning Gross HP ratings - he is correct.

Net ratings were not measured at the rear wheels. They were measured as installed in the car at the crank. So all accessories, air cleaner, exhaust, etc. But still measured at the crank.

[gelvik]

The 80's cop car 318's were 4 barrels.
To the best of my knowledge, they used 360 heads on these and absolutely killed compression.
Up until around 85 or whichever year Carter went out of business, they used TQ's. After that until the demise of the M-body, they used Quadrajets.

[DartGT66]

The 318 four barrell came in the late 70's and was 10 hp over the two barrell. They had the 360 four barrell upstairs. The old compression ratios do not hold true, if you purchase pistons for a 318, there is no high CR or low CR versions. It's true that the older ones had pistons with valve reliefs and the newer ones didn't; the CR is still the same on both. I have used them even mixed, and have measured the CR. With '71 open chamber heads and a composite gasket the true CR was 7.49:1. We took a '75 stock 318 Dart in to a wheel dyno, and it put out 107 hp, still it run 0-60 mph in 10 seconds and burned rubber effortlessly. Chryslers (direct connections) chassis manual used to have "true" power ratings of different chrysler engines, and if I remember correctly the 318's were rated around 150 hp. also, if I remeber correctly, the only mopar engine that really put out the advetrtised hp numbers according to that manual was the 340. And those numbers weren't wheelhorsepower either, but I believe they were close to the current SAE net specs. In my opinion, it doesn't matter a thing how many hotrsepower your engine is supposed to make. The thing that matters is how it runs.

[Dart 65]

Man, DartGT66, I don't even know where to start. You're trying to tell us that there were no differences in compression ratios among the 318s? You're sadly mistaken. I happen to be looking at a chart showing three different compression ratios from 1967-1988. How do you explain that? If you're mixing and matching engine parts, you're braver than I am because I happen to think that's plain stupid. Hell, it's your engine, so you have the right to blow it up in any way you choose. You expect us to believe you're right, but then you turn around and say that the numbers are wrong anyway, according to a book that you once read, citing the 340 as proof. I've got news for you, brother, none of the horsepower ratings were right until 1972, when the US Government required manufacturers to adopt the net horsepower rating system. In fact, they were always underrated to keep the insurance companies at bay. So your '75 Dart is a slug. Other than the fact it needs a tuneup, piston rings, and probably has a vacuum leak, what does that prove? Get you facts straight, pal, before you tell me I'm wrong, okay?

[George G. Leverette]

Chrysler made thousands of 318 four barrels, they came in the late 70s on cop cars, taxis, diplomats, new yorkers and a few I missed. The 318s came with the good heads and a T.Q. carb this is a good combo to put on a short block with a set of duals and 360 exhaust manifolds.

[DartGT66]

I know there are charts rate different compression ratios, but the chambers I have measured and the piston compression heights are the same, between for example a '70 and a '80 318,so it seems to me that the differencies in the CR are mainly on the paper. The chart I referred to about the true power ratings is based on how to expect the cars run with a certain engine / weight combo. I personally feel it's pretty honest one, but if you like to think otherwise, that's up to you. I just tend to believe in the smaller ratings more than the big numbers, because I have busted several "5-700 hp" cars at the strip with combos that have been dyboed at around 400 hp. If someone likes big numbers, that's okay with me, all I'm interested in is how the numbers translate in to reality behind the wheel.
The '75 Dart was no slouch, it run extremely well with the measured 107 RW horsepower. The 318 I built mixing different parts was a zero budget project built with parts others had thrown away. I believe it made about 200-230 horsepower and run 15.2 in a '80 Aspen with a stock converter and 2.95 gears. And has lived strongly for four years so far. If you want to believe that different year stock 318's have almost 100 hp difference in power production, I don't care. It takes nothing away from me.

[Dart 65]

*Yawn* Whatever.

[dave571]

I don't buy horse power ratings myself.

The highest rated 318 was 220 right?

My 73 340 duster(8:1 comp) was rated 230-240(if I remember right)

It was rock stock, and there's no way a stock 318 car could even sniff the tail pipes. That's just the way it was.

Dyno tests, and et's ect, are the only things that can be trusted.

[DartGT66]

Even dynos are just tools, and even the numbers taken from there are in many cases useless when compared to numbers out of another dyno. It's pretty uncommon that dynos have been calibrated between each other, so the easiest way usually to pick up power is to take your engine in to a "good" dyno Unfortunately that doesn't help the performance a lot either.

[platboy]

According to the info I have the 1967 318 2 barrel made 230hp with comp. of 9.2:1. The 1970 318 made 230hp with comp. of 8.8:1. The 1978 318 was the first 4 barrel since 1961, and used the 360 carb and manifold. In 1957 there was a dual 4 barrel 318 (old style casting) that rated at 290hp. This is all from the book Mighty Mopars by Anthony Young pub. 1984. Cheers, James.

[DartGT66]

The difference between a '67 and later 318's may be more evident since the '67 LA still used closed chamber heads. The earlier 318 A four barrell engines are of different engine family, but share some swappable pieces with the newer LA design.