318: too much cylinder head?

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frosty_the_punk

frosty_the_punk

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Hey all, I have some bare Edelbrock heads on the way here for my little 318.
I read this article. I'm sure you're all quite familiar with it

http://www.carcraft.com/techarticles/ccrp_1110_pump_gas_small_block_mopar/

Those cylinder heads look like works of art and I was wondering what something like that would go like on a little 318.

Before everyone says "stroke it" or "get a 360" I'd like to point out that this engine has Steel crank, H beam rods, Domed forged pistons and a fully balanced and blueprinted rotating assembly.

Now, I believe 450-500hp is possible and even streetable with a 3500 stall and 3.7 gears on a 25 inch tall street tire. (98 octane fuel helps too)

The cam I'm looking at is a solid grind, 242/248 @ .050 .540"/.550 lift. 114LSA 113ICL

This might seem mild but the 114 lobe separation should help it rev clear to 6500RPM before it makes peak power Assuming I have enough head flow at lifts up to .540"

Obviously the valve springs would need to be a lot lighter. but as far as the 2.08/1.6 chebby valves and titanium retainers go, should it all be compatible/optimal?

I understand I would probably have to notch the bores even though they are +.030".

The porting, tubing and machine work. how much of it would be worth while and how much of it would be wasted on an engine with only 76% the displacement and 80% as much valve lift?

I understand this was an "all-out" type build but it still flows awesome numbers up to .550"

What are the potential pitfalls of putting "too much" cylinder head on an engine?
 
frosty_the_punk said:
What are the potential pitfalls of putting "too much" cylinder head on an engine?
Click to expand...

There are many pitfalls. Please note - the engine in that article was a 4" stroke, had a thousand-dollar-plus set of rockers on it, had a one-off cam drive system, and no water pump on it. Going by what I've seen posted for dyno sheets they test them with cold water temps (under 150°). So my advice is take it all with a grain of salt because that is not something you'll have in a street car. Impressive, yes. But not easilly or economically repeatable in a street car.
In regard to your plans - the stroke is the key. A 3.31 stroke is easy to "over head". The RPMs in thier out of the box form are good, but are almost too big in terms of volume as-cast. IMO - it's a mistake to port them larger, and install huge intake valves to run on a 318 unless your peak power needs to be made at 7K rpm. You will hurt the flow potential in the area you will be running them in, and in turn hurt throttle response and torque right where you need it most.
 
did you read my post?

first of all I want to make it clear. yes, I do understand this motor would make peak horsepower up near 7000RPM. that's actually the point.

The $1000 rockers are probably 100% necessary for trying to get .683" lift on a fast-rate roller camshaft. I'm however talking about using a .550" lift solid grind.

I'm not a dyno owner/operator and hence would not want/need a one off adjustable belt driven camshaft system.

Stroke is the key? a 3.31 stroke is easy to overhead? Ede heads are too much out of the box? It's funny how this theory seem to only applies to 318 engines and never 340 engines.

and lastly I am not trying to replicate a 414cube 615hp engine build from a magazine article with my 318.

with the theory that it's better to over-port than over-cam an engine.
I'm asking. "what would these heads go like on a 318?"

I should probably also ask. "What would these heads go like on a 340?" (A whopping 5% bigger in displacement than my 318 )
 
Run them. Don't worry.

The "Whoping 5% difference you mention is small as per the % goes but not I. The terms where it is needed to be understood most. And that would be cubic in ha. Say what you want, reason it anyway you like, it won't matter what you say. Your looking at it the wrong way. The bottom li e is cubic inches and not the percent difference.

You made this mistake twice via the Mag article you referanced.

I read your build up list and the heads will work well and IMO as intended via the parts list. I myself would change that 3.7 gear to something higher like a 4.10 or 4.30 and use a 26-1/2-27 inch tire.

You assume wrongly on the bore notch being needed. 2.02 + 1.60 = 3.62 in a stock 3.91 bore. This is plenty of room even with the space in between the valves. While there is some valve shrouding, it is a low concern issue. You'll never notice the difference if you took the steps and machine work to make it better.

On porting the head, it is my opinion that you would be wasting time and money at this level of performance. While some mags may show a gain in power, with such moves, the important part your missing (or the mags as well) is actual road feel and manors in How the engine actually a te and feels.

I have run OOTB Edelbrock heads on a 360 with not much more cam into the low 12's.
(With a 4spd and 4.10's, 27 inch tire.)
Have the heads checked out and cleaned up. That's all you'll need.
 
rumblefish, I know this is off topic. but are you having the same issue I'm having with the cursor disappearing out of the message box while you're trying to type?

RPM and engine displacement are relevant to each other directly.

Like it or not HP=TORQUE X RPM / 5252

therefore mathematically, all things being otherwise equal a 100ci motor would have to rev 2x as many RPM as a 200cu motor to pull the same air through the heads/carbs to make equal horsepower (at a much lower torque level)

Engines in their most basic form are an air pump. you have displace 20% less air per revolution you have a choice of performing 20% more revolutions in the same time period. or making 20% less horsepower.


re: driveline

Perhaps I could gain a tenth or two from changing my gearing and tires however it would completely remove the car's sleeper appeal.

I fail to see how increasing the average port flow in all used lift ranges by circa 30% could NOT cause a gain in net useable RPM and HP especially with a 114LSA cam.
 
The bigger valves and port work will do nothing........but make the 318 run better from top to bottom. I believe it would be difficult to get the ports too big in the Edelbrock head for the way your 318 is built, and that the head is probably too small for a really good running 408 stroker. But what the heck do I know?
 
My apologies if I misunderstood Punk. You said streetable and pump unleaded in your first post.

"I fail to see how increasing the average port flow in all used lift ranges by circa 30% could NOT cause a gain in net useable RPM and HP especially with a 114LSA cam. "

You're not increasing "all lift ranges by 30%". You have an average port flow increase that is just that - an average. And you have gains made at specific lifts - and those are not linear gains. Using published numbers (off the Shady Dell website) the gain at .100 is 5%. .200 is 11%. .300 is 12%. .400 is 15%. .500 is about 26%. That's a fairly typical improvement. Low lift flow is typically not enhanced when the port is designed to flow big at higher lifts. I stopped at .500 because the cam you chose will only lift the valve a max of about .490" when you remove the lash figure and the pushrod angularity. So increases over that will not be providing any help.

On the 114 LSA - Could you provide more info as to your thoughts on that particular choice?

Edit - also - the lower end you said is done... What piston and ring package was used?
 
yes the Edelbrock work and they work great. I have run them on a std bore 318 with a very mild cam 202/208 @.050 417"/441" and made 224hp at 4500rpm on the rears and the car was nice and with lots of torque.

now I have swapped in the purple shaft 284 adv 244 @.050 .528" solid 112 lsa and moroso electric water pump. I'm using 273 adjustable rockers although I have 1.6 stainless rollers to try later. the motor has a very good 4000 hi stall and 3.23 lsd gears and it pegs the tach to 7000 off the line and will do the same if you short shift straight to second gear smoking 255/60/15's like they were cheese cutters. dyno numbers will be coming soon.

oh yeah it still a std bottom end 318 with 645 rods
 
benmopar318 said:
yes the Edelbrock work and they work great. I have run them on a std bore 318 with a very mild cam 202/208 @.050 417"/441" and made 224hp at 4500rpm on the rears and the car was nice and with lots of torque.

now I have swapped in the purple shaft 284 adv 244 @.050 .528" solid 112 lsa and moroso electric water pump. I'm using 273 adjustable rockers although I have 1.6 stainless rollers to try later. the motor has a very good 4000 hi stall and 3.23 lsd gears and it pegs the tach to 7000 off the line and will do the same if you short shift straight to second gear smoking 255/60/15's like they were cheese cutters. dyno numbers will be coming soon.

oh yeah it still a std bottom end 318 with 645 rods
Click to expand...

Damn that sounds like some fun for sure!
 
moper said:
My apologies if I misunderstood Punk. You said streetable and pump unleaded in your first post.

"I fail to see how increasing the average port flow in all used lift ranges by circa 30% could NOT cause a gain in net useable RPM and HP especially with a 114LSA cam. "

You're not increasing "all lift ranges by 30%". You have an average port flow increase that is just that - an average. And you have gains made at specific lifts - and those are not linear gains. Using published numbers (off the Shady Dell website) the gain at .100 is 5%. .200 is 11%. .300 is 12%. .400 is 15%. .500 is about 26%. That's a fairly typical improvement. Low lift flow is typically not enhanced when the port is designed to flow big at higher lifts. I stopped at .500 because the cam you chose will only lift the valve a max of about .490" when you remove the lash figure and the pushrod angularity. So increases over that will not be providing any help.

On the 114 LSA - Could you provide more info as to your thoughts on that particular choice?

Edit - also - the lower end you said is done... What piston and ring package was used?
Click to expand...


I should have clarified. The last time I had this engine running I was running 915J heads, the 30% increase in flow would be from the basis of 2.02/1.6 J heads not OOTB Edelbrocks.

I wasn't aware I'd lose that much lift at the valve due to the pushrod angle. how is this calculated?

The lift at the lobe is .360"/366". If I were to get 1.6 rockers the calculated valve lift minus lash would be .577".587" and this is something I'm considering.

The 114LSA is a means for building an engine that will idle nicely with reasonable street manners and still continue making useable horsepower through and beyond 6500RPM, in theory it should do this with the sacrifice being a loss in midrange torque.

This cam should go well with a high RPM engine like a 318 with hi-flow heads coupled with limited traction (ie street tires) for impressive ET's

At least that's the theory, anyhow.

The pistons are Icon [FONT=Verdana, Arial, Helvetica, sans-serif]ic84530 with diamond file fit moly rings

http://www.campbellenterprises.com/Chrysler-Dodge-Mopar-Pistons-318-Dome-Top-Pistons-ic84530-Icon-Pistons_3219.prt
http://www.campbellenterprises.com/Chrysler-Dodge-Mopar-318-5.2-Magnum-Piston-Rings-09023940-Diamond-Pistons_3215.prt
[/FONT]
 
Can anyone give me any feedback from personal experience using big flow heads (300ish CFM)on a 318/340 sized motor?
 
benmopar318 said:
yes the Edelbrock work and they work great. I have run them on a std bore 318 with a very mild cam 202/208 @.050 417"/441" and made 224hp at 4500rpm on the rears and the car was nice and with lots of torque.

now I have swapped in the purple shaft 284 adv 244 @.050 .528" solid 112 lsa and moroso electric water pump. I'm using 273 adjustable rockers although I have 1.6 stainless rollers to try later. the motor has a very good 4000 hi stall and 3.23 lsd gears and it pegs the tach to 7000 off the line and will do the same if you short shift straight to second gear smoking 255/60/15's like they were cheese cutters. dyno numbers will be coming soon.

oh yeah it still a std bottom end 318 with 645 rods
Click to expand...


Thanks ben, I'd be interested to know what work you had done to the heads and i look forward to hearing about the dyno numbers.
 
frosty_the_punk said:
Can anyone give me any feedback from personal experience using big flow heads (300ish CFM)on a 318/340 sized motor?
Click to expand...

Flow is not how you should pick a cylinder head. You need to know what you want from the engine, and then get the head csa where it should be. If you have a 2 heads, one flows 280 cfm at .500 and the other flows 300cfm at .500, Most times the higher flowing head will have a larger port/valve. If that's what the engine wants (HP, RPM) then it will make great power. If not, it will be a bag of $hit!
Brian
 
To much porting/ over sized valves on a street motor will cause a lag in the bottom. The heads I have are hogged out, with larger valves (cast iron). A friend that has been racing Mopars his whole life said they as good as very worked X-heads, I was going to put them on a 273 , he said no. Yes , I am off topic. However, if you have the right cam, gears, ect, a properly built mill, will pull hard, throughout the power band/ RPM range.
 
Find your rpm span,choose heads and cam as a pair. Mismatched parts,cause you frustration and headaches galore.A aggressive,experienced wrench,can tweak on the fly.Some serious talent here,please take advantage of it.
 
Never to big, here is Aus we have GM 308 with 4.00 bore & 3.06 stroke and you can get big HP out of them - they rev like buggery. Big heads, Massive Cam, 750+ carb and run in the 11s & 12s. The only advantage it has over the 318 is a larger bore so you can get bigger valves in there. The Mopar job is alot better IMO as the bottom end is better & is made to try rev - just look at the rods 6.123 is great....Hmm think I've side tracked myself - if we can do it on these engines, the 318 will be just fine is what I'm trying to say
 
ou812 said:
Flow is not how you should pick a cylinder head. You need to know what you want from the engine, and then get the head csa where it should be. If you have a 2 heads, one flows 280 cfm at .500 and the other flows 300cfm at .500, Most times the higher flowing head will have a larger port/valve. If that's what the engine wants (HP, RPM) then it will make great power. If not, it will be a bag of $hit!
Brian
Click to expand...

Brian, i know you did these heads personally so i appreciate your input. If you were doing up a set of edelbrocks for my engine what would you do differently?

First the cam specs, The idea is for a street/strip 318 that has relatively good manners/idle but also just keeps on winding out past 7K on the strip.

Solid grind 242/248 @.050
114 LSA. 113 ICL.
.577"/.587 Lift w/1.6 rockers and .018 lash
(not taking into account loss from pushrod angle)

please note, I am open to criticism on the cam specs. It may sound a bit mild at first but the idea is "more head, not more cam"

I was originally recommended the same cam with a 108LSA by my cam manufacturer.

It is my own idea to run the 114 LSA for the above mentioned engine qualities (Streetable High RPM screamer)

I'm going to run Holley six pack carbs on a factory dual plane high rise manifold and I don't want to run into issues with the front and rear carbs opening off idle due to low idle vacuum.

I'm planning to clean up the runners and plenum a bit in the six pack manifold, but it doesn't look like there's a lot of improvement to be made.

when we dial in the jetting on the dyno, I am keen to try a variety of combinations for open/2 hole spacers 1" thick.

Compression will probably be around 10.5:1 with alloy heads, it has to be safe for 100 degree weather. The 114LSA should help bleed off a little from the dynamic ratio too.

I'll have to open the chambers some to be compatible with the dome pistons or vice versa.

Headers are 1-3/4" with 30" tubes into a 3" collector.

What is the maximum amount of head work you would build for a customer with an engine like this?

Would a full-house set of ported edelbrocks make it run like a "bag of $hit"?

If so what would you change in regards to porting, valve size and/or camshaft compared to the heads in the CC build?
 
You should check out Dr DJ's air wolfs they flow 300 cfm @ .500 but there 220cc ports.
 
I've been playing with a 318 with the Air Wolf heads in my dyno program with a 262 comp cam with 1.6 rockers and is making a pretty flat powerband from 2500-6500 with 450hp/450lb-ft
 
The airwolf220 heads were under strong consideration but in the end I decided that due to the international shipping cost, tax, customs etc I am better off spending the money locally to have my Edelbrocks built.

But yes I'd like to get numbers comparable to those, I understand the pushrod pinch is optimized on those castings just like the indybrocks?

I'm in pretty good with a machinist/builder who does top work and I trust him 100%.

He actually builds 5L ford and chev engines to the tune of about 650hp for a couple of teams in our nation's flagship motorsport, the V8 Supercars. but most importantly he has a passion and knowledge for mopars!

Also $3000 is a lot of money to spend in one go, it's easier on the wallet if I spread it over a couple of weeks.
 
273 said:
I've been playing with a 318 with the Air Wolf heads in my dyno program with a 262 comp cam with 1.6 rockers and is making a pretty flat powerband from 2500-6500 with 450hp/450lb-ft
Click to expand...

is that cam the XE262H-10?

if so, I would consider that extremely mild for an engine with Airwolf heads and perhaps not such a great match.

Which dyno program do you use?

I use engine analyzer Pro.

Here is the printout of My results for my proposed 318 build.



Please note, "Idle vacuum" as listed is taken at 1500RPM.

This is purely for indication and to a large degree, entertainment. to a lesser degree, education and trends.

I realize this is probably not as accurate as it could be, given that volumetric efficiency peaks at 107%

The port volume for this calculation was 211 for the intake, 85 for the exhaust. and the flow numbers are taken from Shady Dell's ported edelbrock graph. all other specs are as listed above.

If you are having trouble zooming in on this picture. try holding CTRL and pressing the "+=" button on your keyboard.
 
Listen Punk...can I call you Punk?? Ha ha...anyways, mr. frosty (I like snowman better but that's just me) here is the major problem...street/strip!
Anytime you need to have an engine pull double duty you compromise alot...and the smaller the engine the larger the compromise!!

The sixpack setup is very restrictive in OOTB form. So beware!

The heads will not be the cork in this combo, it'll be the small engine + need for street drivability + 6pack setup.
Cam I would choose would be closer to 232@ .050 intake, 242@ .050 exhaust, on a 110 lca and advance it 6°. Don't worry about idle, as you can tune the carbs to work with less than 12".
Now if you were to go with an 8" converter you can run a larger cam.
 
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