which would be better
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412 Stroker
Well-Known Member
I've been told the magnums are better, but do your self a favor and get the RHS heads from IMM engines that's what I would have done, I had mine redone locally and I got screwed, I wasn't or didnt even know about this website at that time, but at least I do now....
dgc333
Well-Known Member
The general concensus is stock magnum heads with stock 1.92 / 1.62 valves will flow better than stock LA heads with 2.02 / 1.60 valves. The numbers I have heard are you will pick up 20-30 HP just by replacing stock LAs with stock magnums.
Both heads respond to porting about the same put the magnum head will still have the advantage of a closed chamber which will allow for higher compression and be more detonation resistant.
Both heads respond to porting about the same put the magnum head will still have the advantage of a closed chamber which will allow for higher compression and be more detonation resistant.
1wild&crazyguy
Banned
total BS.
why would you tell this guy that complete bs?
A 2.02 j head flows 220'ish cfm from the factory
A magnum head flows 190-204cfm from the factory
But heres the kicker....they[magnums] have lil potential in them due to being thin walled smog heads and the biggest names in porting-hughes/shady dell can only get them to 250's MAXED OUT.thats a quote.
Call hughes and ask them wether the mag head or the J head, and they will all tell you to skip the pos magnum head, for performance it's junk.
and no closed chamber is gonna be worth the hp/cfm loss.
AND if the exhaust port was so good, why does it flow the same as an LA head meanwhile having a larger exh valve than the J head?
hughes will not even touch factory mag heads anymore, did you know that?
btw Even 308 heads are junk, they max out 260's.
Hughes/shady/Will tell you the only factory heads that are worth doing are J heads and magnum R/T's[which are a COMPLETELY DIFFERENT PORT THAN THE TRUCK MAGNUMS.FYI
I've ported my own J's and they flow 270's at .500 lift and 280's after .500!!!
j'S WILL GO 290'SCFM, EVEN '675' 318 HEADS HAVE BEEN TO 270 CFM, WHERES THE MAGNUM, i DON'T SEE IT ANYMORE??....OH YEAH...IT's DOWN THERE HOLDING THE DOOR OPEN.LOL
They are great stock FI truck pieces, but thats only when they aint cracking.
Leave the mag'ems on the trucks and get some real performance heads.jma
I would either shop around on re furb and port work and or look into RHS LA-X heads from brian at IMM in indio california.
moper
Well-Known Member
It's more a money thing really. I don't believe there is a huge HP boost to run with Magnums, but there are gains to be had over stock LA stuff because of the combination of chamber and faster ports. Especially if you are building from a clean sheet or paper and can accomodate the closed chamber design better. You can now buy performance designed Magnum type heads for about the same cash as properly doing a set of LAs. So it comes down to cash and what you can get the stuff for really.
dgc333
Well-Known Member
1. Because people keep swapping open chamber LA heads for magnum heads and make more power.
2. Because the MP 360 crate motors with magnum heads make in the range of 400-420 HP verse the previous 360 LA based crate motors in the 360-380 HP range, both with stock factory heads.
3. Because when Mopar Muscle did a small block dyno challenge a couple of years ago there were two schools of thought; Go all out with after market heads or stay with factory heads. Every single competitor that went with factory heads used magnums not one LA head based engine and these guys were getting well over 500 HP with ported magnum heads. When these guys make there living on the reputation of building power they aren't going to choose an inferior head.
4. Because according to the flow numbers currently posted on the Hughes site the magnum intake (1.92) port out flows an LA head (2.02) port in the range of .2" to .4" of lift then they are virtually the same to .6 with the LA having a slight 1 to 2 cfm advantage. BUT the magnum exhaust port starts off with a 4 cfm advantage at .1" lift and continually increases that to a 36.4 cfm advantage at .6" lift compared to the LA. And those are the types of differences I typically see posted. Then factor in that you can run at least another full point of compression due to the quench you can obtain with a closed chamber you will realize about a 5% power advantage which is another 20 on a 400 HP engine.
IMHO before I would not spend any money on porting factory heads i would purchase the Hughes Iron Ram or the RHS heads. But if I had magnums and LA's sitting on the bench, the magnums all the way.
EL5DEMON340
Well-Known Member
they are very close in flow j's to magnum, i like the shaft mount of the j's better, Most of the F.A.S.T. racers are getting in the 280's cfm intake flow with J's and making about 480 to 500hp with exhaust manifolds. Switching to magnum heads now doesn't make much sense with Eddys and the rhs etc...
1wild&crazyguy
Banned
1. who are these people you mention, I'd like to meet them.
2. mag crate motors have bigger roller cams in them, it ain't the heads.
3. Engine masters were needing any and every advantage they could get, even in the $$$ department, they would rather use an off the shelf aftermarket piston that did not have to rework to in order to squeeze all the cylinder pressure they could on a givem octane=it's rules/limits/cost
The closed chambers are nice , but what about the rest of the picture?
4. the mags have larger valves than the 1.88 smog casting they put them up against, thats apples to oranges.
when the flow reaches 90% or stops climbing period, thats when the flow value go's up, wether the operator chose 88% or 92% before he up'd the value or not will show a HUGE diff on the numbers.......
total BS still.
2. mag crate motors have bigger roller cams in them, it ain't the heads.
3. Engine masters were needing any and every advantage they could get, even in the $$$ department, they would rather use an off the shelf aftermarket piston that did not have to rework to in order to squeeze all the cylinder pressure they could on a givem octane=it's rules/limits/cost
The closed chambers are nice , but what about the rest of the picture?
4. the mags have larger valves than the 1.88 smog casting they put them up against, thats apples to oranges.
when the flow reaches 90% or stops climbing period, thats when the flow value go's up, wether the operator chose 88% or 92% before he up'd the value or not will show a HUGE diff on the numbers.......
total BS still.
dgc333
Well-Known Member
1. if you follow the various mopar forums people post these kind of results all the time. There has been enough magazine articles where back to back coparisons have been done that show the results too.
2. The 360/380 (which actually dynos in the 400-420 range) has 230/234 @ 50 .508 lift cam. The MP 360/360 (which dyno in the 360-380 range) LA crate motors used the 284/284 241/241@50 .484 cam. Magnum has a lift advantage and the LA has a significant duration advantage. They both came with M1 intakes so the only other contributor is the heads. Just can't see where the roller cam in this situation is providing any advantage.
3. In the dyno challenges the competitors are assessed penalty points for spending money on aftermarket parts and there is no penalty for using factory parts. The game is can I make enough more power with an after market part to offset the penalty. Either magnum or LA heads are factory parts so there is no penalty to using either. For all of the competitors that went with factory parts to choose the magnum head would tell any reasaonble person that the magnum head has an advantage over the LA head.
4. According to the Hughes web page the LA head used was a 576 casting with 2.02 intake valves. The 576 casting was an MP head released as a replacement head for the 340 that was legal for Stock and Super Stock racing. They were even available drilled to accept offset rocks for TA motors. Hardly a smog casting and certainly a fair comparison.
Have no idea what you are trying to say here. Measuring flow through a cylinder port is a straight forward process. You maintain a constant pressure drop across the port (typically 28" of H2O) at each valve opening setting and measure the flow going through the bench. They way the flow is actually measured can vary; orifice plates, pitot tubes, anemometers, etc can all be used to measure the flow. All of these measurement methods have advantages and disadvantages and is a big part of the reason that tests done on different benches have such a wide variation in results. The really only way to compare numbers is for tests done on the same bench.
2. The 360/380 (which actually dynos in the 400-420 range) has 230/234 @ 50 .508 lift cam. The MP 360/360 (which dyno in the 360-380 range) LA crate motors used the 284/284 241/241@50 .484 cam. Magnum has a lift advantage and the LA has a significant duration advantage. They both came with M1 intakes so the only other contributor is the heads. Just can't see where the roller cam in this situation is providing any advantage.
3. In the dyno challenges the competitors are assessed penalty points for spending money on aftermarket parts and there is no penalty for using factory parts. The game is can I make enough more power with an after market part to offset the penalty. Either magnum or LA heads are factory parts so there is no penalty to using either. For all of the competitors that went with factory parts to choose the magnum head would tell any reasaonble person that the magnum head has an advantage over the LA head.
4. According to the Hughes web page the LA head used was a 576 casting with 2.02 intake valves. The 576 casting was an MP head released as a replacement head for the 340 that was legal for Stock and Super Stock racing. They were even available drilled to accept offset rocks for TA motors. Hardly a smog casting and certainly a fair comparison.
Have no idea what you are trying to say here. Measuring flow through a cylinder port is a straight forward process. You maintain a constant pressure drop across the port (typically 28" of H2O) at each valve opening setting and measure the flow going through the bench. They way the flow is actually measured can vary; orifice plates, pitot tubes, anemometers, etc can all be used to measure the flow. All of these measurement methods have advantages and disadvantages and is a big part of the reason that tests done on different benches have such a wide variation in results. The really only way to compare numbers is for tests done on the same bench.
EL5DEMON340
Well-Known Member
Then its settled the x/j flow about 220 cfm in stock 2.02 form, dulich did a flow on a stock x way back and it was over 220 cfm flowed more than a BB 906 head, those x/j's are a big reason the 70/71 demon dusters were mid to low 14 sec cars stock.
All of this is build dependent and any head can show a gain or loss. Building a engine with a Magnum head in mind can yeild more power than a letter head and vice a versea.
Arguing and pointing out which head does what in a ported form is a moot point and may very well not fit this particula build of the OE poster. His build is vauge to start with and this argument is close to pointless and may only confuse the OE poster.
1W&C, DGC has very good points on which to argue. In a maxed out for, the LA heads win, but is this allways good for the design of the engine or a simple street car? Is a bigger port allways wanted?Needed? A must have?
We both know that answer is a big NO!
Sometimes a smaller port and valve head is exactly what the engine needs/wants even if the flow is down vs another head.
The only advantage the roller cam has over the MP Hyd. cam is that friction is down a slight bit and if it is on a Magnum head, a "LA" roller cam now has the extra intencity and lift from the rocker ratio change.
Though, I do not think this the case in the create engines which out power the "LA" create engines with a zero difference between them in the shrt block.
Arguing and pointing out which head does what in a ported form is a moot point and may very well not fit this particula build of the OE poster. His build is vauge to start with and this argument is close to pointless and may only confuse the OE poster.
1W&C, DGC has very good points on which to argue. In a maxed out for, the LA heads win, but is this allways good for the design of the engine or a simple street car? Is a bigger port allways wanted?Needed? A must have?
We both know that answer is a big NO!
Sometimes a smaller port and valve head is exactly what the engine needs/wants even if the flow is down vs another head.
The only advantage the roller cam has over the MP Hyd. cam is that friction is down a slight bit and if it is on a Magnum head, a "LA" roller cam now has the extra intencity and lift from the rocker ratio change.
Though, I do not think this the case in the create engines which out power the "LA" create engines with a zero difference between them in the shrt block.
This is really a build dependent question and requires a bit of details to make a decent judgement.
If it is a build that will require nothing more than a stock head, then a stock head will do. Just prep it with decent valves and a good 5 angle valve job.
LXguy
Well-Known Member
If you're thinking of porting and 2.02ing magnum heads, just get the Iron Rams from Hughes. Cheap and effective. You'll have less in them than rebuilding and/or porting stock stuff. You'll have actual unleaded fuel seats, and if you so desire you can port the snot out of them.
Another alternative would be the Indy X deals, which have the advantage that you can get the shaft rockers if you've got an LA block. Brian at Indio says the EQ (aka Iron Ram) castings actually flow better in some regards, and the EQs have a 58cc chamber to start with.
Good luck with your build.
Steve
Another alternative would be the Indy X deals, which have the advantage that you can get the shaft rockers if you've got an LA block. Brian at Indio says the EQ (aka Iron Ram) castings actually flow better in some regards, and the EQs have a 58cc chamber to start with.
Good luck with your build.
Steve
dgc333
Well-Known Member
Just be careful about flow numbers. According to the Shady Dell web pages the stock J-heads with 2.02 valves flowed 200.8 CFM and the 576 LA heads Hughes tested flowed 212 CFM and the magnums 209. As a comparison the as cast 2.02 Iron Ram head flows 247 cfm on the Hughes bench.
I don't know where the numbers previously sited came from but it was not from the Hughes or Shady Dell web page.
And as I previously stated the variation from flow bench to flow bench can be quite significate so the only real comparison that can be made is tests performed on the same bench.
I farted.
72dart_swinger
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You have done that a lot lately :-D
1wild&crazyguy
Banned
1. magazine shmagazine, they are looking to sell and advertise, and with the help from the westech bunch, yeah thats realistic.....
2. You aren't being honest here, if you were, you would have fessed up to the 1.6 rocker arms that are 'stock' on a mag'n'em head, so out with the few degrees of duration on the LA 360 to 'make it fair' crap. BTW it's time at max lift with a roller compared to the nano second of max lift on a flat tappet.
3. the head hughes used were not 576 heads they were 596 heads=smog heads that I would not use due to the short turn being different than what I like to see, yes there were differences , most don't really know this and just read about it.
4.Flow values, research it sometime, or better yet...talk to a local with a flow bench 'who has experience'.
What flow without port restriction=the flow value
The actual port flow #'s reflects how much test flow is actually flowing through the port itself, as the port reaches 90% of the flow value with increase in lift, you then increase the value/flow control knob.
A port could never see the the 90+% till it's lifted way past the reasonable typical amount of lift. You could show crummy flow easy if you wanna push it to the 90+% and make the low/mid lift numbers look like crap.
some operators will lift the valve .050 in increments only gaining 1-3% for .200 of the lift range, instead of just upping the flow value when the % flowed slows way down and is realistically not gonna get the desired 90+% of the value, that show as poor numbers, and in some examples rightfully so, but others like ones the creep at 80-85%...just up the value already.
last set of heads that I had flowed used 2-4 values of 74.1,153,303 on the int. and where form .350 to .450 only picked up 10%, and only 3% in a .050 [.4-.45lift increase, should or could of raised the value @.400 and had better numbers but didn't.
Someone who should chime in is Brian from IMM, he knows a lot more about flow bench than you or I.
He can tell you about plugs and plug removal in relation to flow value increase and at what percentage he raises it at or if he does raise it when the % port flow vs test flow lags/slows.
straight forward, not so much....there are tricks, like cnc'd radiused fixture plates and more...
1wild&crazyguy
Banned
Thing you must see is that when building around a head, you able to compensate...that is as long as the flow is there.
so you want quench??? use quench dome piston already..
You want increased ratio?? buy a set of rockers.
Now some might say...''oh, but the magnum has'em stock''-1.6
Oh yeah??? well I don't know about you, but I run a decent sized cam when I'm building power and those non roller pedestal rockers don't have rollers last time I checked, so I guess those just useless to me unless I want to trash my guides and simply wear sht out.
And port volume?....better cc those magnum's cause 155cc on j head aint big when it comes to 340-360cid...btw notice the higher roof by looking at the port window on a j head? think that has a lil to do with why they might flow more?, yeah.
I said before and I'll say it again, the magnum heads were designed with smog requirements and fuel injection in mind, closed chambers help this, but also can impede flow=shrouding.
smaller port window-'sometimes the case' is either a mix matched combo in which air speed from a smaller port window is only a band aid for poor blue printing/too big a carb etc.. and usually ends up as a trade off else where in the power range.
As for low lift flow ...I didn't know high 190's @.300 & 230's and high 240's at .400 lift was crummy low lift flow, I must have missed that in my mopar engines book...lol
1wild&crazyguy
Banned
because for a while that was what was new and what they could still 'sell'
see they quit making the old heads LONG ago, no money there for them.
BTW at this point...they don't make'em anymore so now it's on the next hot'est/popular head out there, the rhs or eddy etc..whatever the magazine want to push these days.
keep in mind they also did a 400 hp 318 with old j heads in the magazine, mild combo too.But no one parades that sht around like they do the mag'em....
It's not like the new heads suck and thats it, it's just that they are not better than the older design in the flow depsrtment, they make it up with 1.6,and a closed chamber but after point...none of those 2 things will account for the massive diff in flow between the new and old heads.
they will work for 'some' and the 'some's' expectations, but not for me.
I will not build around a head with that many handicaps, the trade of is not worth it to me.
1wild&crazyguy
Banned
yes, decide wether he wants all the mag related parts change over and then make the choice with the indy's/iron rams being the better ootb bang for your buck.
1wild&crazyguy
Banned
I agree with you here, diff bench=diff #'s.
as for the info ...it was stan weiss, proair, J&J performance & total performance .
As for the J&J test up in ridgecrest ca , my 1.88 j 's at the time flowed 206cfm @.400 lift, thats converting the 25'' to 28'' #'s
who's numbers I actually trust...only the ones I've had done my self, the rest is blaaah to me and only a reference in this discussion.
stroked 340
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Half of what you read in those rags is printed just to get people to buy them...
dgc333
Well-Known Member
1. Sure magazines are looking to sell magazines & advertising and they certainly don't want to trash the product of one of their advertisers, BUT, what motivation do they have to be dishonest when they take an engine with factory parts and swap on another factory part and report that the second factory part makes more power. Certainly a lot less motivation than someone that makes a living porting heads and makes a statement about how much they can improve a head when they work on it. I'm not saying anyone is telling fibs but you just have to consider who might have motivation to streach the facts some.
2. And why do you think I am being dishonest? The valve lift on a cam designed specifically for a given engine is advertised with that engines rocker ratio. That .508 lift I mentiond is with 1.6 ratio rockers. If it were with 1.5 ratio rockers the valve lift would be .541 on a 1.6 ratio and the retainers on a stock magnum head hit the valve guides at .525. Since the crate engine has stock heads its pretty clear its not .541.
3. You better call up Hughes right away and tell them their web page is wrong. They state they tested 576 heads. http://www.hughesengines.com/TechArticles/1headflowcomparisonsupdated112009.php
4. I have never sat down and tested the flow in a set of cylinder heads but in my 30+ years as an engineer I have tested air flow through all sorts of other products and have seen cylinder head flow benches, the process is the same. I still have no idea what you have said, maybe you understand but can't express it or maybe you have no idea and are throwing out a bunch of double talk.
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