SBM Swirl Port Heads

[dm440c]

Apr 23, 2013 11:16:58 GMT -5 Imperialist said:

Apr 23, 2013 10:32:36 GMT -5 dm440c said:

Not sure I agree with that, I think when it comes to throwing cash around it is generally cheaper to make power with a Brand X engine because the aftermarket support is stronger. The beauty of the Chrysler engines is that they are better engineered in the stock configuration which means you can do more with less, but the further you get from stock the more you have to spend to keep up with the other guys. Speaking in the most general terms of course, it is all relative.

The 318 heads have such tiny ports and valves that it is not the slam-dunk you think it is to put them on a 360. Yes you gain compression but you give those benefits right back in terms of airflow. If you fiddle fart long enough you may find some gains overall but by the time you get there you'll wonder why you didn't just go with aftermarket heads in the first place.

I preach this stuff all the time but I think a lot of guys are taking too schizophrenic of an approach to engine design. Not to discourage anyone from some adventurous pursuits into experimentation, but when it comes to engines you just can't have it all... everything that you do is a compromise. The smart engine builder understands compromise, understands how to prioritize, and puts together a total package that works together. Thinking in terms of the total package what the goals/priorities are prevents you from taking the long road to a short gain.

The engine builder needs to ask himself: What do you really want? Power, reliability, affordability, how much time do you want to put into it, what is the budget, what specifically are the goals.... think it through and put your resources only into the things that achieve the goals. Avoid all those mismatches of parts that result in two steps forward and one step back... or worse.

Lastly, what chaps my cheeks are the guys who throw some ill conceived experimentation together and then declare it a success suggesting others should do the same without actually having any kind of data to back their claim. Beware the placebo effect.... be aware that just because you expect in your mind that it will "run better" can mean that you perceive it to "run better" without actually knowing.

Do you consider Mopar Muscle data to back a claim? It's where I got the idea... There is no "fiddle farting" around here or placebo effects. Bolt them on and out perform X and J heads! It's not always about valve size, that's why I mentioned to watch the radius while porting.

I agree with the bad advise chapping me as well.

Swirl Port Heads
Chrysler's small-block cylinder head design changed very little until 1987 when the 302 casting (last three digits of the casting number), commonly known as the swirl port, was introduced. While the 302 casting, as well as the later 308 casting, were most commonly found on low-performance 318s, they shouldn't be overlooked for a performance build. Even with small 1.75-inch intake and 1.50-inch exhaust valves, the design of this head's heart-shaped quench-style combustion chamber makes it a good choice for mild to moderate performance. An engine with these heads in stock form will outperform an engine with stock X or J castings simply due to the improved combustion chamber design. Additionally, these heads have hardened valve seats, which make them compatible with unleaded fuel. The swirl port heads were utilized through 1991 (302 casting) and 1992 (308 casting) and respond well to port and bowl work, offering better power potential than all of the earlier small-block heads. Another nice feature of these heads is they utilize valvetrain and intake manifolds common to early small-blocks, so parts are readily available. Simply bolt these heads to your small-block and enjoy the extra power they provide.

Read more: www.moparmusclemagazine.com/techarticles/engine/mopp_0607_mopar_cylinder_head/viewall.html#ixzz2RItcNJpQ

yes absolutely I consider that to be a good source for information. I have made the swap myself as far as putting the swirl port 318 heads on an older 318 that originally had open combustion chamber heads, and my inspiration to try it the first time was Mopar Muscle. Especially on street vehicles... I have a set of 302 heads on a 318 in my Ramcharger beach vehicle that it did not come with, and I made the swap specifically to improve torque and fuel economy. Mopar Muscle for years had a contributor named Steve Dulcich (sp?) who is extremely knowledgeable about Chrysler cylinder heads and porting. Next time you're poking around the internet doing research, try to look up some of his writings and you'll find a treasure chest of info that very few other people are willing to publish.

You may have misunderstood the context of my remarks.... read the first sentence of the second paragraph right before the "fiddle fart" comment you quoted. I am referring to putting 318 heads on a 360 as being a questionable move in terms of what you get and what you give. It's a similar debate as putting 360 heads on a 318; if you just plop them on there you get results that may not demonstrate an actual improvement. If you address the design difference by matching the parts for optimum benefit then you definitely will see an actual improvement, but it still comes with a compromise as all changes do. Managing goals, priorities, and compromises is how the smart engine builder gets more out of his engine for less consumption of resources.

My other point about data is meant to address the spirit of experimentation- it is fine to experiment but if you have no reliable way to measure results, how do you know if your experiment was a success or not? Too many people try an experiment and expect good results, so they may perceive success without really knowing if they achieved it since there is no real evidence to confront their expectations. In the case of horsepower, this is something that can be directly measured and although repeated dyno sessions are beyond the reach of many derby builders, there is a plethora of published data out there including data from reliable sources such as Mopar Muscle and others.

[dm440c]

Apr 23, 2013 12:08:15 GMT -5 blackmopar21 said:

Holy f@ck dude. Did I come off in a serious manner when I said that? It didn't seem so to me. It was a joke not a statement.

black and white type does a poor job of conveying mood and inflection.... no, I understood where you were coming from completely... we're just having a polite conversation. Rapping 'bout engines, same as we would do in person over a couple of frosty beverages. Your comment inspired me to wax poetic for a while because I just had this exact same conversation with a friend a couple of days ago... over a frosty beverage... and it has been my longheld belief that Chrysler had the best engineered factory engines in the original musclecar era but that the aftermarket has supported the other guys more; and so speaking in the most general terms Chrysler engines have an advantage at stock or near stock conditions but gradually the pendulum swings away as you get further and further into modifications and expanding levels of power production. Which is not to say you can't compete at a high level with a Chrysler engine, but you will almost certainly pay more to do so.

[Imperialist]

"You may have misunderstood the context of my remarks.... read the first sentence of the second paragraph right before the "fiddle fart" comment you quoted. I am referring to putting 318 heads on a 360 as being a questionable move in terms of what you get and what you give. It's a similar debate as putting 360 heads on a 318; if you just plop them on there you get results that may not demonstrate an actual improvement. If you address the design difference by matching the parts for optimum benefit then you definitely will see an actual improvement, but it still comes with a compromise as all changes do. Managing goals, priorities, and compromises is how the smart engine builder gets more out of his engine for less consumption of resources."

I still disagree. In stock form they will outperform stock X and J heads. And have more potential than all earlier LA heads. That's what the article says... I had a Stock Eliminator (talk about research and data) racer buying all of them off of me that he could get to run on his 273 back in the late 90's, so I did some reading. You can do whatever floats your boat. I would recommend these heads to any small block derby builder.

NHRA SuperStock Legal Cyl.Head Volumes

"302" Intake Max CC 162 Exhaust Max CC 70~ 1.78"/1.50" Valves
"915" Intake Max CC 158 Exhaust Max CC 75~ 2.02"/1.60" Valves

Little 302's?

[dm440c]

Yes, I see that part in the article where they make a vague reference to comparing the 80's swirl port heads to the 340 and 360 X and J heads, but I think this may be poor word choice with some misleading conclusions. The problem here is they were very non specific and no data is cited to support the conclusion.... Somewhere they also have an article about putting different heads on a 318 where they directly compared J heads to stock 302 heads, then did multiple stages of port work on the 302 heads, plus a few other configurations and - this is the important part - they published a table of data for flow and dyno results. I searched for a little while but haven't found it yet, I'll look some more when I get home from work.

I still think you're misunderstanding what I am saying. I am a fan of the 302 heads for the right applications, I am not arguing against them. But I am arguing against using them inappropriately and then advising others to do the same. Nowhere in the article cited did Mopar Muscle tell you it's a good idea to toss a stock set of 302 heads on a 360 or anything else.... they really didn't get into the details of any swaps at all in that article. It's just a high-level article in overview format to give folks an introduction to some of what is out there. It would be jumping to conclusions to say the least to take what is written there and launch it into action.

[dm440c]

ok, I spent an hour on Sunday morning with a cup of coffee looking for the reputable data that I know is out there somewhere but gave up and moved on with my day before I could find it. I did find several independent websites with flow data to support my position but I hesitate to cite such things as reliable sources for info.... somewhere there is at least one published magazine article with flow bench data (from memory it was a Steve Dulcich effort) showing the swirl port 318 heads in stock form, then with enlarged valves, and then with a couple of stages of porting and then similar data for some 360 heads (from memory, the article used late 70's #596 heads) and it isn't until you get to the really advanced stages of work that the flow of the 318 heads start to catch up so.... y'all will have to decide for yourselves if you want to go with my feeble memory's version or if you want to do your own research. Honestly I always recommend the latter and personally I always expect to see data before I start believing what people tell me so no hard feelings for the skeptics out there if you want to discount what I am saying since I did not offer much data to support it.

However, I'll re-state my position and present it to the readers as opinion rather than fact until I stumble upon the supporting data I'm looking for.

- 302 (or other swirl port castings from 85-91) heads in stock form make a nice upgrade for a stock pre-1985 318
- 340/360 heads (several casting numbers to choose from) in stock form work well on a 340/360 but not so great on a stock 318 for two reasons: (1) the large combustion chambers drop static CR well below 8:1 with factory 318 pistons and (2) the large port volumes (about 40-50 cc difference in stock form) and large valves (1.88/1.60 vs. 1.78/1.50) reduce velocity. This is a one-two punch killing low to midrange power production and efficiency with stock 318 pistons.
- stock 318 swirl port heads aren't so great for 360 engines because the small ports (about 40-50 cc difference in stock form) and small valves hurt breathing pretty bad. You do get a benefit from the static CR bump taking you north of 9:1 but all things considered I would predict the engine would show some moderate gains in the low end and then fall on its face real early into the midrange. Matching up a different cam than stock might help even it out some but I have some serious doubts about it being a good combination for demo derby. That's just an assessment based on the numbers, I'd love to see some dyno data of that particular swap to see how close I am on my guess.

- The biggest thing here is the theme I like to stress- matching all the parts of an engine for an intended goal is the key to a good engine design. Closed vs open chamber heads, port work, valve size, head gasket thickness, stock vs. aftermarket pistons, camshaft, induction system, and driveline details should not be a half-a$$ed collection of random parts. If you don't know the answer, do the research and science it out or find a machine shop/engine builder who actually knows a thing or two to help. Experimentation is never discouraged but experimentation without measurable results to make an assessment of the different conditions that were compared is about useless, and you should always be skeptical of conclusions that are presented in this form.

[99x]

i like the roller coasters as six flags :-). sorry the info that has been coming on this thread is overwhelming lol