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Cyl head sizing discussion, anyone?

I don't see how some feel a larger diameter lifter does not keep the valves open longer than smaller diameter lifters. Please correct me if I am wrong, but are the lifters not opened when it hits the ramp and closes when the ramp leaves it? That's like saying it takes the same amount of time to run a half mile as it does a quarter mile, although much exaggerated. It does stay Open until it passes the entire diameter of the lifter. Keep in mind, we are talking in an apples to apples comparison here. Yes, cams can compensate for smaller lifters with wider lobes or air input can be compensated for with larger heads etc, but isn't that the point of this thread, to see why we can still keep up with smaller heads and/or cams in similarly sized engines? To me, who is admittedly an amateur, it just makes sense. An engine is an air pump and there are different ways to improve efficiency and we do it differently than a Chevy does. Jmo
 
No, but the diameter of the lifter allows the use of a larger cam. If the edge of the lifter hits the lobe first, then you will have a wiped out cam.
 
...but isn't that the point of this thread, to see why we can still keep up with smaller heads and/or cams in similarly sized engines? An engine is an air pump and there are different ways to improve efficiency and we do it differently than a Chevy does. Jmo

No. The point is to discuss head sizing based on displacement and intended usage, not pat ourselves on the back for 'keeping up' (which is debatable...and interesting choice of words, btw).
 
Hughes has a good Q and A section about the advantage of the .904 diameter Mopar lifter.

They make more usable power because with the faster rate-of-lift you get with the larger diameter lifter, "there is more time (called area under the curve) for air to flow past the valve. At each degree of rotation, the valve is open higher than it is with a standard (big block Chevy) slow rate-of-lift cam."

http://www.hughesengines.com/TechArticles/1camshaftfrequentlyaskedquestions.php
 
No. The point is to discuss head sizing based on displacement and intended usage, not pat ourselves on the back for 'keeping up' (which is debatable...and interesting choice of words, btw).

I really don't think we're even keeping up. MOPARs need some real heads as well as some good aftermartket blocks. And who cares how big your lifter is if you're still using an old cam grind from the 70's!

I think there are better heads available for Pontiacs and buick than there are for MOPARS these days!
 
I'm not sure what's unrealistic about it. An engine's an engine...different specifics, but they all do the same
thing...some just do it better than others. The question is why? Not all LS engines have Al blocks, and I've never known there to be a power advantage to using one at these moderate hp levels. LS engines make even more power w/ a single plane and a carb, so FI isn't a consideration. 383's can be built w/ higher compression, and have aluminum heads available. The question is what can be done to make more power, not a comparison of two engines built as delivered from the factory from different eras. What can we learn from the newer stuff...maybe to apply some of the principles if possible?

You want to keep moving the target around so you can win an argument. OK, well you could take the Mopar 383, put some aluminum heads on it, a roller cam, and higher compression like the LS has and probably match the 480 hp the LS crate has.

Purpose built race cars.

Yes, the F.A.S.T. car are purpose built race cars but regardless of brand they all have to start with factory cast blocks and heads.

Yes, assuming the timing events occur at the right times, more power will be made in either scenario. What compromises must be made in each, esp for a car seeing time on the street? It appears camshafts of equivalent sizes will make much more power in an engine w/ what are conventionally thought to be ‘too large of a head’. Have you also noticed that in some racing classes, superior heads require a weight penalty?

So your allowed to bring up purpose built race cars but I'm not?

There’s not enough information here to draw any kind of conclusion.

I'll try to give all the info I can. '70 Barracuda vs. '67 Satellite. Both 440/727. Both running DOT slicks. Barracuda has 4.10 gears, Satellite has 3.91 gears. Barracuda has Edelbrock RPM heads, Satellite has unported 452s. Hooker headers both. Both cars built like something out of the old Direct Connection manual. .484 lift hydraulic in the Barracuda, .534 lift hydraulic in the Satellite. The Barracuda had to weigh at least 50pounds less just by virtue of the cylinder heads. Also, the Barracuda had the battery in the trunk and the Satellite doesn't. Barracuda was at least two tenths slower in the 1/8 at the same track. Why since it had heads that flowed at least 60 cfm more? I can only surmise that the better flowing head needs a cam with enough lift before it becomes an advantage.

I’m trying to understand what you mean by this. HP is nothing more than a byproduct of torque and rpm. I would say that getting the engine into its powerband quickly and keeping it there would be the most effective way of accelerating the mass of the car. That’s torque converter or clutch slippage though, which is a drivetrain issue, not engine. Making the most avg hp in the powerband is the concern, where the powerband consists of maybe a couple hundred rpm past peak to as low as the engine rpm falls back to between shifts.

I agree with you here. I guess what I was trying to say is that don't get too hung up on peak HP numbers from a dyno because of the old saying of "you can't race dynos", Even if I could afford it, I will never use one because I don't see the point when I have a track I can go to test and see real results of my tinkering.

Over and over again on these message boards I see people who will never take their car to a track worrying about if they will meet certain HP goals they have. They've read stuff on message boards and magazines and think they need to keep up with the Joneses.

Don't get me wrong, I know the big heads are better and will make more power and torque and as soon as I have the money I will upgrade but a lot depends on intended usage, goals, and budget which I don't think you stated what yours are yet.
 
You want to keep moving the target around so you can win an argument.

Ummm...I have no idea what you're talking about.

Me said:
I just saw an ad for a crate LS3 direct from GM...the thing is completely stock as they deliver in their Camaros w/ the addition of a 219/228 at .050" camshaft (mild for 376 ci, yes?), and it's rated at 480 hp. Are there any examples of 383's producing this kind of power w/ such a mild cam?

...at which point you started talking about factory 383s, where I never mentioned such a thing. The 383 reference was an attempt to be equivalent to the LS3's 376 ci. Doesn't look like a moving target to me...?

OK, well you could take the Mopar 383, put some aluminum heads on it, a roller cam, and higher compression like the LS has and probably match the 480 hp the LS crate has.

Proof? This is the closest thing I can find. Open to any other builds that may fare better...

http://www.moparmusclemagazine.com/techarticles/mopp_0605_mopar_performance_383_stroker_engine/

So this 432 ci 'B' makes 545 hp w/ a 250ish degree duration cam @ .050", ported RPMs and Vic intake. I would not call this a really mild camshaft.

545 hp/432 ci = 1.26 hp/ci

the crate LS3... 480 hp/376 ci = 1.27

Still more output w / the LS3, and w/ a MUCH smaller cam. WHY CAN'T WE HAVE THIS? IF WE CAN, HOW DO WE DO IT?

I'll try to give all the info I can. '70 Barracuda vs. '67 Satellite. Both 440/727. Both running DOT slicks. Barracuda has 4.10 gears, Satellite has 3.91 gears. Barracuda has Edelbrock RPM heads, Satellite has unported 452s. Hooker headers both. Both cars built like something out of the old Direct Connection manual. .484 lift hydraulic in the Barracuda, .534 lift hydraulic in the Satellite. The Barracuda had to weigh at least 50pounds less just by virtue of the cylinder heads. Also, the Barracuda had the battery in the trunk and the Satellite doesn't. Barracuda was at least two tenths slower in the 1/8 at the same track. Why since it had heads that flowed at least 60 cfm more? I can only surmise that the better flowing head needs a cam with enough lift before it becomes an advantage.

Still not enough data to come to any conclusions about. Rear tire size/diameter, converter, 60', ambient temp/pressure, coolant temp, shift RPM, carb, jets, tune mighta been off, timing, car weights - not a guess, wheel weights/diameter, front tire size/pressure, etc, etc...see the problem? A lot of little things can add up...and there are A LOT of unknowns.


I agree with you here. I guess what I was trying to say is that don't get too hung up on peak HP numbers from a dyno because of the old saying of "you can't race dynos", Even if I could afford it, I will never use one because I don't see the point when I have a track I can go to test and see real results of my tinkering.

Over and over again on these message boards I see people who will never take their car to a track worrying about if they will meet certain HP goals they have. They've read stuff on message boards and magazines and think they need to keep up with the Joneses.

Don't get me wrong, I know the big heads are better and will make more power and torque and as soon as I have the money I will upgrade but a lot depends on intended usage, goals, and budget which I don't think you stated what yours are yet.

Engine and chassis dynos are invaluable tools. I would much rather experience an engine failure during testing on a dyno than on the street or racetrack.

I don't think it's 'keeping up w/ the Joneses', but I do look at what these smaller engines are doing and wonder why most BB wedges are trailered to the track and at best run mid-11s to mid-12s...w/ a decent amount of aftermarket stuff on them. Old school thinking is mostly to blame, I think.

For the record, I think RPMs are a nice stock replacement head. 'Performance'? Maybe w/ a big enough cam...

My goals? Still being defined. 550-575 hp or so w/ a slight idle would be nice, no bucking and stuff under 1300 rpm w/ no load is a def goal, though...stick shifts are unforgiving. Overall plans are a docile street car I can take on Power Tour that will have 18" Foose Nitrous wheels (plan on painting the centers an 'as cast' grey color)...so ET's don't matter to me...I'd also like to get between 18-20 mpg out of it on the highway. I'm not one for lumpy cams. Last engine in my Mustang went high 10s at ~130 w/ a 5 speed on 255/50R16 MT DRs w/ stock wide wheels on the front...just a hint of a 'cammed' idle, but quieter than a stock 5.0...turbo and 3 mufflers made it super quiet. People had no idea...it was great. 25 mpg at 60 mph too.
 
Well, if all you want to do is cruise down the highway during Powertour on some 18" Chip Foose wheels, I don't think you will need 575 hp to do that. You could save yourself a lot of time and money.
 
Well, if all you want to do is cruise down the highway during Powertour on some 18" Chip Foose wheels, I don't think you will need 575 hp to do that. You could save yourself a lot of time and money.

With a set of good aluminum heads, 575hp doesn't take a ton of work, time, or money on a 440 and can be very streetable.

I dont have a lot of cash in mine...... Bottom end is a factory steel crank, Scatt H-Beam rods with the higher rated studs "not that much money", Forged "lightened" L2295F pistons, Main stud girdle, Rotating Assy balanced like I would on any build. The heads and cam provide the final number to my HP rating.... I drive it around without issue at all and dont have a fortune in it either...
 
You can get 550 easy and very street able with a 512 stroker kit, a well worked set of 906 heads or aluminum heads and a pretty mild cam. Well, mild for that cubic inch anyway. That is how mine is set up, with a 2200 rpm stall and 323 gears. I went for as streetable a set up as i could get with a performance motor. I got it, kinda. Very acceptable idle rpms, cruising rpms etc, but do NOT touch the gas out of a corner unless you are pointed the right way! LOL. I can roast the tires at launch, 30 or 60 mph in my automatic with ease. For the record, burnouts are not burnouts when you have to use the brakes! Lol To find a crate motor with the same performance specs would cost 2 1/2 - 3 times what I have in mine and it should be dead nuts reliable. Time will tell, but I didn't have to go crazy with lifts and or use big/offset rockers etc.
 
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like comparing bing cherries to a grapefruit

I think port size shape, height, location & length has allot to do with why the LS engines do so well, hp/per ci, it's not just port volume & were the port is or if it's higher & straighter may be a better advantage than a fat squatty big port... also I'm pretty damn sure camshafts newer better split profiles efficiency, have allot to do with how the LS makes it's power too, allot of engineering, not just lift, it's ramp-speeds, overlap, lobe centers, duration, base circle sizes, valve-train parts weights, valve sizes, even bore sizes, whether the valves are shrouded by the cylinder walls or not & ci. etc., {kind of Bing cherry & Grapefruit} Not really a good idea comparing a BB Mopar Wedge to a LS engine, when the BBM wedge it's a far closer head design to a ol' SBC 265-400ci in style shape, short runner lengths, valve angle size etc., you can take a BB Mopar Max Wedge head & put it on a stock 440 or even 383 bottom end & pick up probably 40-50 crank HP or more, with a mild hyd. cam change, the 906 & MW heads are very similar but MW is taller/higher, wider & straighter ports with a higher floor too, along with bigger exhaust ports, the shape of the port is a big part of where & why they make more power, not just size/volume... 575hp isn't all that hard to get out of a stock 3.75" stroke 440, 280cfm tuned properly will get you there... Flow is very important to making HP/TQ, bigger valves will help more flow too, pocket shape makes a world of difference too, a higher rocker ratios will help make more flow too with all the exact same parts... It's not just head volume & port shape, exhaust tubing size can make a big difference too, too big of an exhaust tube on the header will kill bottom end torque, header length vs tube size vs head flow vs cubic inches can make a 50+hp difference too, {the height of the carb & how far the carb is from the intake valve, can change your exhaust flow too, maybe why the tunnel ram works well up-to between about 3500-6500rpm, below that or after that, parts need to be changed, internally, to take advantage of the long runner & free fall effect, kind of poor mans supercharger},where the exhaust port is makes a big difference in how the gasses & exhaust exits, flow rates making more power when they are raised {intake &} exhaust port like the Victors compared to the std. location of the RPM's... There's a formula about cylinder head flow ideally can make if done properly IIRC 2.06hp/per cfm of flow, upto about 2.5hp/per cfm of flow, naturally aspirated {before you get into all out race engines}, vs a stock BBM 906 cylinder head that flows 220cfm on a good day, would be good for in the neighborhood of 453.2hp if tuned correctly, do a good performance multi angle valve job or increase the valve size it can be a little better in the formula would increase in value {now this doesn't take any cubic inch increase into consideration, there's a formula to compensate for that change too}, if you have the same long block under it with heads that flow 300cfm & get that same 2.06hp/per cfm you get 618hp, you can see how much difference just the cylinder head can "possibly" make... Carb size & intake design shape & height, or a spacer type/style, even will make a night & day difference in air flow.... Then much more with a forced induction/turbo-ed/supercharger or N20... There are some great books on engine mathematic formulas, flow & why & where you make power, camshaft design etc... I highly suggest getting a few of them... Trying to compare a BBC & a BBM especialy a wedge head, with both having completely different style, shape, height, floor shape, length, exhaust port location/sizes, volumes & valve sizes of their respected heads, even bore size for a specific set of heads is like comparing a bing cherry & grapefruit, totally different things, they do not have much in common... sorry I probably didn't make much sense, best I can explain it, with out writing a damn book... I highly suggest you listen too & read any of IQ52's posts on the subject here, he covers all the issues very well, I'm sure he can explain it better than me too, DC .com & Mopar Muscle forums too, he knows what he's talking about... here are a few books you may want to look at & buy, there are many others too... ok I'm done

- - - Updated - - -

I'm not going to answer a bunch of questions line by line either, justify what I said/typed, I broke it down the best I know how, now it's up-to you guys/gals to do the research to learn & understand cause & effect, instead of a needless bickering back & forth... or believing everthing you read on the internet or on these forums even, get with a good engine builder & stick with a certain style of build... Don't fall for all the hype, especially from engine builders {like some mentioned earlier} trying to sell you their heads or their combos or magazines using a bunch of thrown together parts, when they are selected for a certain build, by suppliers, it's allot of slight of hand & special parts to make them look better when tested, given to the rags, for advert. considerations, published in the mags... allot of it is BS & Hokum, salesmanship... trial & error
 

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also runner length & diameter play a VERY important roll in the COMPLETE package, ls engines have a long runner. almost ALL newer engine designs use variable runner length technology, i played with large valve & ports on my old harley on my dyno,it was very interesting, because what i was doing EVERYONE said it will be a torque less wonder.

the graph is on a 94 cid 2 cyl, 3 7/8ths bore with 2.08 intake valve, the pink lines are with 22in long runners,the blue lines are 8 in runner,everything on the engine is the exact same EXCEPT RUNNER LENGTH & fuel curve,even though the long runner made less peak hp,on the street it would kill the short runner,,also notice how the torque curve with long runners has power surges at different rpms,that is the pulse effect of long runners.

so my point is, if done right, large port & valve & fairly small cam can be made to work,seat duration on the cam in the test was 272.

sorry its not a mopar engine test,but all engines are air pumps & just wanted to share some info that does apply to all engines.

179017_146166262108758_4570743_n.jpg
 
Bud(the novel writer)nicks,

You make some good points. You must have started that post in the early evening and finished it the next morning. Right?

I can't speak to some of the things being discussed because I haven't tested them.

What I can do is say, when I tested this combination, it did this for me. Coming up soon is a 440, running 9-9.5:1 compression. Starting with a Comp Cams XE285HL cam and 1.6:1 rockers, we will test it using 346 heads w/stock port windows, flowing various amounts until we get them up to around 290-300 cfm. At that point in time we will switch to our Max Wedge ported Indy EZ heads that are flowing some 340 cfm at the maximum lift of the XE285HL cam with 1.6 rockers. Comp says the lobe lift should be .364, but our cam tested out to .359 so we'll have .574" lift on the intake and exhaust. If it will seal, we will put the stock port window RPM Performer intake right up to the Max Wedge ports of the EZ heads, test it, and then use a single plane Max Wedge intake with a Dominator on it and see what happens. We should be having some great fun in the next few weeks if we can get the heads finished.

At least we'll know how a 440 with a XE285HL likes some real Max Wedge ports and big 2.25" valves. Of course there are some solid rollers on the shelf around here someplace..........

lesse.........

where did I put those cams....................?
 
Bud(the novel writer)nicks,

You make some good points. You must have started that post in the early evening and finished it the next morning. Right?

LOL... yeah it was a short post, to begin with, but it seems I never can leave well enough alone, I started adding more variables to it, well you see what happened, like normal, it becomes a damn novel... I just can't write a simple post with out a bunch of elaborating & explanations etc.... I'm so damn fickled sometimes...
 
Bud(the novel writer)nicks,

You make some good points. You must have started that post in the early evening and finished it the next morning. Right?

I can't speak to some of the things being discussed because I haven't tested them.

What I can do is say, when I tested this combination, it did this for me. Coming up soon is a 440, running 9-9.5:1 compression. Starting with a Comp Cams XE285HL cam and 1.6:1 rockers, we will test it using 346 heads w/stock port windows, flowing various amounts until we get them up to around 290-300 cfm. At that point in time we will switch to our Max Wedge ported Indy EZ heads that are flowing some 340 cfm at the maximum lift of the XE285HL cam with 1.6 rockers. Comp says the lobe lift should be .364, but our cam tested out to .359 so we'll have .574" lift on the intake and exhaust. If it will seal, we will put the stock port window RPM Performer intake right up to the Max Wedge ports of the EZ heads, test it, and then use a single plane Max Wedge intake with a Dominator on it and see what happens. We should be having some great fun in the next few weeks if we can get the heads finished.

At least we'll know how a 440 with a XE285HL likes some real Max Wedge ports and big 2.25" valves. Of course there are some solid rollers on the shelf around here someplace..........

lesse.........

where did I put those cams....................?

I cant wait!!!!!
 
My problem is with people who think power is all about the head. You can make more power with a smaller head engine that's setup properly with matching cam, c.i. size, carb(or f.i). Honda kids always build the head's in their cars and stick it on a stock block/stock cams and complain about how they don't pick up numbers on the dyno. Honda heads already flow like crazy from the factory, I don't understand.

I wish /6's had aftermarket head options, even race ported heads with the biggest valves possible rarely flow above 200cfm, theres one that I think flowed 220, and he made like 350hp all motor on alcohol. Only way to make jam on slants is with lots of boost. :(
 
My problem is with people who think power is all about the head. You can make more power with a smaller head engine that's setup properly with matching cam, c.i. size, carb(or f.i). Honda kids always build the head's in their cars and stick it on a stock block/stock cams and complain about how they don't pick up numbers on the dyno. Honda heads already flow like crazy from the factory, I don't understand.

Your second sentence - more power than...?

As far as Hondas, their heads are FAR superior to any pushrod head in its design. No pushrod to force a port to go around, TONS of curtain area due to having 4 valves/cyl, variable valve timing to help control airspeed, centrally located plugs.... Hp gains will only be seen when eliminating the limiting variables, which for Honda/Acuras, is NOT the head...to a point, of course (rpm/boost). As a general rule of thumb in the world of pushrods, it's a safe bet to concentrate attention and effort on the heads.
 
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