1970Duster
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If your willing to use a stroker and have to "freshen" it up, just think of it as gotta pay to play.
340-360 vs 408-414
- Thread starter 273
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If your willing to use a stroker and have to "freshen" it up, just think of it as gotta pay to play.
I think I'm starting to get this, I couldn't get why Chev people are running away from 400 Chev rod ratio and we're going towards them. But what I'm starting to see is most 408-414 are engine built mainly for summer toys, street strip or full out drag racing. I guess bore/stroke and rod ratio would be more important in high HP & RPM endurance engines like NASCAR I've been playing around with my dyno software bore/stroke and rod ratio seem to make little differance on final output. But in a daily driver like my Jeep would I see an reduction in engine life say like 10-20%?
moper
Well-Known Member
Rod ratio isn't a big deal really. But short pistons, lost ring seal and ring pack stability are huge. Life span is directly related to quality of machining and parts, quality of assembly, and rpms. The higer the rpm the faster the wear and the sooner the freshening is required. Generally, my expectation for a 4" stroke engine is a good service life of 40-50K in a mostly street car with mild gearing. For most cars where I am, that's anywhere from 4 years to forever...lol. Usually if they are going to be daily driven they'll have really mild gearing and/or OD anyway and that extends the life.
Have to consider fuel injection,and the application. I built a healthy 408,sticking in the mid 5000 to loe 6000 rpm is where they do their best work.Mild builds alaways benefit from stroke.
A good rod to stroke ratio is important in anything. chebbie just happens to have some of the worst. lol It's not that "we" are going towards the 400 rod to stroke ratio. That's only the by product. Those that choose to build strokers are going toward more cubic inches. The inferior rod to stroke ratio happens to be something you overlook in order to get the bigger cubes. It's not like you're going to have a failure, as lots of engines run ratios in the 1.5s or less.
The advantages of a high rod to stroke ratio are, the piston speed is slowed, allowing more "dwell time" at top dead center thereby receiving a bigger push from the combustion. I think it is a very sound theory.
Also, as the rod to stroke ratio goes up, the angle at which the connecting rod pushes against the piston decreases. This leads to less stress on the piston skirts and cylinder walls in the thrust areas. Hell, the STOCK rod to stroke ratio in a Chrysler 383 and 400 is 1.88 right from the factory. The chebbie boys would kill each other for that. lol
It really boils down to what you are gonna do and what you want to do. 1.88 is certainly a better ratio than 1.55. Would you ever feel the difference in a street engine? Probably not. You'd have to see it on a dyno sheet. But I firmly believe there would be a difference.
The advantages of a high rod to stroke ratio are, the piston speed is slowed, allowing more "dwell time" at top dead center thereby receiving a bigger push from the combustion. I think it is a very sound theory.
Also, as the rod to stroke ratio goes up, the angle at which the connecting rod pushes against the piston decreases. This leads to less stress on the piston skirts and cylinder walls in the thrust areas. Hell, the STOCK rod to stroke ratio in a Chrysler 383 and 400 is 1.88 right from the factory. The chebbie boys would kill each other for that. lol
It really boils down to what you are gonna do and what you want to do. 1.88 is certainly a better ratio than 1.55. Would you ever feel the difference in a street engine? Probably not. You'd have to see it on a dyno sheet. But I firmly believe there would be a difference.
In wear absolutely,Stroker.About camming a stroker compared to a 340/360,I would like your ideas.I grew up on square port Chevies,Short r/s ratio.Big heads,high compression,big cam.For the Chev,the shorter"dwell time" yanks harder on the Airflow/fuel mix. Dodge small blocks were "locked in" when they installed the La headed block,within the narrow confines of an early a body.Better rod/stroke ratio makes up for stock weaksuck heads.
I'm flattered......but really not qualified. LOL I don't know enough about ports and flow and which heads blah blah blah to really make a good decision.
I can tell you what I would DO were I to build another stroker. I've built four. Two 408s and two 416s, but all were with factory iron heads and mild builds by todays standards.
I know the W2 heads are somewhat obsolete by today's standards, but that's what I'd use. Fully ported with the largest valves they can stand. What can I say? I'm old school and they still flow like a ****.
As for cam, IMO, a large displacement engine with great flow in and out benefits from a single pattern on an LSA of 110 or even 112. Solid roller of course since all this is hypothetical.
I guess ultimately I would have to sit down and talk with my head porter and see what he thought about it. As I said, I am really not versed enough to get real deep into ramp approach and depart angles, port shapes, sizes and placements.
Interesting how those posts show back up,in a hurry.Actually stroker,W2 s were on my want list,no go.I went Eddys tweaked,280 @.500 to .55 lift.That is where that 260@ .050. 106 hydraulic came from.Idled nicely at 1100,5 inches of vac.I appreciate honest answers,that is why I pointed this at you.Textbook means nada,without real world,common sense back up.Thanks.
dodgetkboy78
EDELBROCK HEADS SUCK!
Pulease.......
GM heads are better? Flow? So what, the geometry is horrible, the valve angle is horrible, the combustion chamber is horrible. GM SB heads are the ultimate example as to why you CAN'T race a flow bench!
Just comparing two styles of factory engine building.You know well as I do,stock heads sucked until 340 stuff came out.
dodgetkboy78
EDELBROCK HEADS SUCK!
No, they didn't. They were fine for a 273, and 318, IF they had've built a 4bbl 318, and put effort into making them build power, other than marine, the 327 would've been outpowered, with the 318 using the small port heads..(factory speaking).. You have to remember, we had 361's, and 383's in place of the 340 and 360 back then. A body cars were the only line that suffered.
In all reality, the REASON why the 273 ran better than the 283, was because of the smaller head design. (among other things, rod ratios, etc) but still.
In all reality, the REASON why the 273 ran better than the 283, was because of the smaller head design. (among other things, rod ratios, etc) but still.
The reason I LISTED THE CHEVY CONCEPT was to compare two different style factory concepts.Chev heads were a crutch for deck heighth/rod to stroke ratios.Dodge went with a better r/s BEACAUSE OF HEADS THAT DO NOT FLOW AS WELL AS CHEVY.Two ways to skin the same cat.
I'm not sure I go along with chebbie heads flowin better.
moper
Well-Known Member
It's getting harder and harder to find unmolested or quality W2 and W5 heads. The Indy -1s are the same animals tho... Albeit with some updating. If you're contemplating an upgrade, they would be a solid and available choice.
Isaac
Active Member
I would go nonstroker and use the fantastic bore to stroke ratio of a 340.Get some killer w2 series heads with a small solid roller, build it correctly and go turn some rpms.Or just use an large cube rb somehow.
How much of each of those increases is decrease in frictional loss from a shorter piston? The piston is usually lighter as the rod gets longer.
SB Mopars don't start off in the rod ratio hole like some other brands.
SB Mopars don't start off in the rod ratio hole like some other brands.
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