Magnum VS Hemi

[DionR]

I wish Mopar had put together a “car” version of the Magnum. Something that wasn’t truck oriented and didn’t need gobs of low end torque. Something that would pull to 5500-6000 RPM, rather than run out of breath at 4800 like they do with the stock EFI intake.

I bet 345 horsepower would have been easy. I know it’s not hugely different than what the Dakota R/T guys build, and I know they are making well over that.

I’ve been dying to try making a different intake, but don’t really have the equipment. I’d like to take the beer barrel intake and drill a 3”-3 1/2” hole starting in the top front of the intake all the way back to the rear wall, horizontally, cutting through all of the intake runners. Then weld a mount over the hole in the front for an LS throttle body. Come up from the bottom and cap the runners to make the plenum smaller and to get rid of the plenum plate issues. Then maybe knock out the extra runner material that isn’t connected to the cylinder head anymore, just to make it lighter and cleaner. Lastly, plug the TB mount holes on the top.

That would make a front TB intake similar to the current practice. It would require building a new front mount assessor setup to clear room for the TB, but it’s not impossible.

Then I would mount a pair of Neon/PT Cruiser ignition coils (same as the Viper’s ran) under my new plenum and remove the distributor.

Just need a new tune in the ECU (or a new system) and a method of running a distributorless ignition (MegaSquirt and a Ford EDIS module come to mind). I bet it would make for a slick motor that made more than enough horsepower.

 

[jammied]

Pre 96 magnum factory pcm's are easy to short cut and. Retro fit into older cars and mopar still manufactures the mopar pcm. The fuel lines also would be easy to adapt. Been there it just takes some time Unwraping a factory harness

 

[273]

Main difference between LA, Magnum and hemis is head packages. Magnums have lot of potential in stock form as we see how cam, headers and 4 bbl can get over 400 hp but 5.7 hemis flow so well it would be like if magnums came with Eddys stock. SRT ones have race car flow numbers.

 

[DionR]

Main difference between LA, Magnum and hemis is head packages. Magnums have lot of potential in stock form as we see how cam, headers and 4 bbl can get over 400 hp but 5.7 hemis flow so well it would be like if magnums came with Eddys stock. SRT ones have race car flow numbers.

Aint that the truth. If I had my MP R/T's ported, they might match up with the early 5.7 head, but the later 5.7 or any of the 6.x heads would kill me. But the R/T head isn't an OEM head, either.

 

[rklein383]

I think the new hemi's are ugly. I am going with a 5.9 in my 71 Barracuda because of ease, cost, and nostalgia.

 

[magnummopar]

Main difference between LA, Magnum and hemis is head packages. Magnums have lot of potential in stock form as we see how cam, headers and 4 bbl can get over 400 hp but 5.7 hemis flow so well it would be like if magnums came with Eddys stock. SRT ones have race car flow numbers.

Edelbrock LA RPM heads flow 247 cfm at .500"
Gen 3 5.7 Hemi heads flow 261 cfm at .500"
Stock replacement EQ Magnum heads flow 252 cfm at .500" (with 1.92 intake!!)
Mild ported EQ Magnum heads flow 277 cfm at .500" (2.02 intake valves)

Take into consideration that Ported EQ heads w 2.02 are cheaper than the eddie heads and with the right cam will produce well over 450 HP if not closer to 500, what can I say but
Make mine a magnum....cheapest HP out there hands down.

 

[magnummopar]

I wish Mopar had put together a “car” version of the Magnum. Something that wasn’t truck oriented and didn’t need gobs of low end torque. Something that would pull to 5500-6000 RPM, rather than run out of breath at 4800 like they do with the stock EFI intake.


The stock intake is not to blame, its the ignition. Replace the champion plugs gapped at .035 and they will pull well past 4500. Also, you cant expect an engine with a .439 lift 114 deg center cam to pull past 5000 but if you swap out the cam with say .550 on 112 or 110 then it should pull up to 6000. The beer keg manifold has over 16" runners. Remember when John Lingenfelter was building 180 + mph vetts and camaros? His signature manifolds were 15-16" runners. Those might have been GM mills but not one you would want to screw with in a small block Dart. Longer runners make for more than atmospheric pressure at the port ie a small supercharger. The Hughes RPM airgap only does about 1500 rpm higher than the stock kegger and not as much down low. Dont know about you, but I dont typically take my V8 cars in the 6K RPM range, more power and torque at say 4800-5200. On the street, torque is king. My Audi turbo is another story though.

 

[Infecteddog]

I wish Mopar had put together a “car” version of the Magnum. Something that wasn’t truck oriented and didn’t need gobs of low end torque. Something that would pull to 5500-6000 RPM, rather than run out of breath at 4800 like they do with the stock EFI intake.

I bet 345 horsepower would have been easy. I know it’s not hugely different than what the Dakota R/T guys build, and I know they are making well over that.

In their apps, it was unnecessary. The vast majority of trucks did not have enough gear to have more cam- that's why Ford, Chevy, and the Hemi trucks didn't make them look horrendous stock. The extra 70-100hp most other truck motors had would never see usage even in a full 1/4 mile.

The stock intake is not to blame, its the ignition. Replace the champion plugs gapped at .035 and they will pull well past 4500. Also, you cant expect an engine with a .439 lift 114 deg center cam to pull past 5000 but if you swap out the cam with say .550 on 112 or 110 then it should pull up to 6000. The beer keg manifold has over 16" runners. Remember when John Lingenfelter was building 180 + mph vetts and camaros? His signature manifolds were 15-16" runners. Those might have been GM mills but not one you would want to screw with in a small block Dart. Longer runners make for more than atmospheric pressure at the port ie a small supercharger. The Hughes RPM airgap only does about 1500 rpm higher than the stock kegger and not as much down low. Dont know about you, but I dont typically take my V8 cars in the 6K RPM range, more power and torque at say 4800-5200. On the street, torque is king. My Audi turbo is another story though.

All depends on what kind of power you want to make, and how you're going to make it. Stroker doesn't need to turn as hard to return better power numbers- especially with boost.

 

[DionR]

Gen 3 5.7 Hemi heads flow 261 cfm at .500"

Maybe for the 03-08 5.7 head (the baby of the four OEM heads), but a Magnum head couldn’t compare to any of the other 3 heads.

Ranges of 320-340 cfm for the Eagle, 6.1 and Apache are pretty hard to compete with, without porting. Even Dr. J’s Airwolf 220 CNC ported heads don’t make the cut.

The stock intake is not to blame, its the ignition. Replace the champion plugs gapped at .035 and they will pull well past 4500.

I find it hard to believe that plug gap would affect the RPM potential of a motor much. Maybe a couple hundred RPM, but a 1000 RPM?

Also, you cant expect an engine with a .439 lift 114 deg center cam to pull past 5000 but if you swap out the cam with say .550 on 112 or 110 then it should pull up to 6000.

Doubt it would pull that high with a kegger intake (shortened runners or not), but I never said I was blaming the lack of higher RPM potential on the intake exclusively. My focus on the intake is really only because it is the only part not available. There are plenty of cams, and heads, but nobody that I know of makes a dedicated EFI intake (meaning not a converted carb intake) for the Magnum. I’m not saying a converted carb intake doesn’t work, but a dedicated EFI intake is just something that has captured my imagination.

The beer keg manifold has over 16" runners. Remember when John Lingenfelter was building 180 + mph vetts and camaros? His signature manifolds were 15-16" runners. Those might have been GM mills but not one you would want to screw with in a small block Dart.

Info I have found says the 6.1 intake is about 3 inches shorter than the kegger. The LS1 is about 2 inches shorter than that. The later GM LT1 intake is supposed to be about 6-7” long in the runner, about the same as the more recent GM RamJet intake. Based on that, I am speculating that shorter runners would be useful.

Also, just a guess, but I would bet the kegger intake runners are pretty small in volume. Even though the 6.1 intake is only 2” shorter, I bet it kills it in volume. So, I am guessing, making the runner shorter would help with the lack of volume.

Lastly, the Allpar article where they flowed a bunch of Magnum intakes showed the stock kegger intake flowing about 180 cfm, and a modded one only flowing 10 cfm more. 180 cfm is good for maybe 340 hp based on one of the calculator I found (one said 180 was only good for 260 hp), but I bet that is the extreme and 300 hp is about the best you would see in the real world. And virtually everything I have read says the modded kegger help some in the middle of the RPM band, but doesn’t help much on the top.

Longer runners make for more than atmospheric pressure at the port ie a small supercharger.

Not at high RPM’s where they starve the engine for air. I'm sure you know all this but, runner length is tuned to a certain RPM range and outside of that it hurts it. Long runners are great for low RPM and for making torque, but not high RPM or horsepower. Short runners work well for higher RPM hp, but don’t make as much low end torque. It’s a trade for sure, but if you don’t need the low RPM torque because you aren’t trying to get a 4500 lb truck moving, and you have the RPM potential to use a deeper gear to make up for the loss of low end torque, I think it makes for a more enjoyable motor (within reason).

Dont know about you, but I dont typically take my V8 cars in the 6K RPM range, more power and torque at say 4800-5200.

I’m not looking rev it past 6K, but it would be nice if it pulled to some RPM close to that (there is a difference between rev-ing to an RPM and pulling to an RPM).

In their apps, it was unnecessary. The vast majority of trucks did not have enough gear to have more cam- that's why Ford, Chevy, and the Hemi trucks didn't make them look horrendous stock.

No argument. Not wishing they had build a “car” version for a truck, wishing the past had worked out different and there had been a RWD Mopar that needed a good performing V8, in the later 90’s.

 

[sireland67]

I wish Mopar had put together a “car” version of the Magnum. Something that wasn’t truck oriented and didn’t need gobs of low end torque. Something that would pull to 5500-6000 RPM, rather than run out of breath at 4800 like they do with the stock EFI intake.


The stock intake is not to blame, its the ignition. Replace the champion plugs gapped at .035 and they will pull well past 4500. Also, you cant expect an engine with a .439 lift 114 deg center cam to pull past 5000 but if you swap out the cam with say .550 on 112 or 110 then it should pull up to 6000. The beer keg manifold has over 16" runners. Remember when John Lingenfelter was building 180 + mph vetts and camaros? His signature manifolds were 15-16" runners. Those might have been GM mills but not one you would want to screw with in a small block Dart. Longer runners make for more than atmospheric pressure at the port ie a small supercharger. The Hughes RPM airgap only does about 1500 rpm higher than the stock kegger and not as much down low. Dont know about you, but I dont typically take my V8 cars in the 6K RPM range, more power and torque at say 4800-5200. On the street, torque is king. My Audi turbo is another story though.

I would love to be there when you start that stock mag headed engine up with a .550 lift cam. It should provide some great entertainment with all the parts breakage.

I have a 94 360 mag, and a 5.7 hemi, each engine has its place.
This is photo of the mag, might throw it in my old power wagon, yes the date stamp is correct in the photo.

 

[Infecteddog]

Maybe for the 03-08 5.7 head (the baby of the four OEM heads), but a Magnum head couldn’t compare to any of the other 3 heads.

Ranges of 320-340 cfm for the Eagle, 6.1 and Apache are pretty hard to compete with, without porting. Even Dr. J’s Airwolf 220 CNC ported heads don’t make the cut.

That would speak to a story where they simply don't compare. It's not the case. Even stock casting head small blocks have strong potential so either the cfm doesn't matter that much or there's something very significant going on.

Lastly, the Allpar article where they flowed a bunch of Magnum intakes showed the stock kegger intake flowing about 180 cfm, and a modded one only flowing 10 cfm more. 180 cfm is good for maybe 340 hp based on one of the calculator I found (one said 180 was only good for 260 hp), but I bet that is the extreme and 300 hp is about the best you would see in the real world. And virtually everything I have read says the modded kegger help some in the middle of the RPM band, but doesn’t help much on the top.

Thanks for quoting that, very interesting. Chances are trying to figure out small block horsepower from cfm isn't going to be very successful. As a basis for "more" or "less"- should be sound, but "how much", I believe I'd not try for that. I can readily believe the kegger is the largest limitation on the stock Mags, followed by the 360 cam, the exhaust, the 318 cam, the stock ports, and then the stock intake valve.

Lots use the Magnums as the basis for high performance builds and the heads have just about taken over across the board for small blocks for pretty valid reasons.

No argument. Not wishing they had build a “car” version for a truck, wishing the past had worked out different and there had been a RWD Mopar that needed a good performing V8, in the later 90’s.

But "nobody wanted rwd performance cars", which is obviously why everyone bought Chryslers instead of Fords, GMs, etc... Since FWD was so great and popular.

 

[Abodybomber]

Magnums are the best bang for the buck it's hard to come up with reasons to go any other way when it comes to dollar bills. The stock short block off tons of power potential.

This,273 nails my opinion down. The top end parts are expensive ( what Mopar isn't?) , the short block is a really usable piece. I prefer carb,in my current situation. If I did F.I.,a couple systems I may look at later.
As for the high numbers on the E.Q. 1.92 heads: 233 -237 @ .500-.550, a head porter here thinks they will go 240 with a good valve job? Is some cutter /bowl work done on that 250+ cfm 1.92 intake, or is some of the newer sets out of the newer foundry? (Latter just asking,I read things..)

 

[murfman]

I'm currently building 2 408 strokers for my boat, and possible a 3rd 5.9 for my 98 Wrangler. Just following the local Craigslist ads I have found:

A 99 5.9 complete with all accessories and a computer/harness for a manual trans for 400$
B 99 5.9 no harness or accessories but complete TB to oil pan for 250$
C 98 5.9 bare block for 150$

I sold off the keggers and pieces I didn't need along with all 4 heads for 200$ back. I will be running EQ heads on all 3. The boat motors are a priority, and I'll have the machine shop pick out the best 2 of the 3 to build for it. I'm still up in the air on the Jeep I may go with a 5.7. To go with the Hemi in the Jeep I need to change the dash harness, then I can make the stock EFI work. If I keep my 98 wiring I can use the 99 Manual trans harness I have.

Magnums are still plentiful and cheap here around Chicago, just getting up there in age and probably needing to be refreshed.

 

[sireland67]

I would not waste money on the 5.7 mag swap in jeep, unless you are going to run a auto trans, way too expensive to fit it in there.

 

[Infecteddog]

I'm currently building 2 408 strokers for my boat, and possible a 3rd 5.9 for my 98 Wrangler. Just following the local Craigslist ads I have found:

A 99 5.9 complete with all accessories and a computer/harness for a manual trans for 400$
B 99 5.9 no harness or accessories but complete TB to oil pan for 250$
C 98 5.9 bare block for 150$

I sold off the keggers and pieces I didn't need along with all 4 heads for 200$ back. I will be running EQ heads on all 3. The boat motors are a priority, and I'll have the machine shop pick out the best 2 of the 3 to build for it. I'm still up in the air on the Jeep I may go with a 5.7. To go with the Hemi in the Jeep I need to change the dash harness, then I can make the stock EFI work. If I keep my 98 wiring I can use the 99 Manual trans harness I have.

Course you could also use a '80+ Dodge 4x4 727 or regut a 904 to go behind the 5.9 if it'll be auto. (should probably get a 727 if it'll be auto...)

 

[Abodybomber]

I would not waste money on the 5.7 mag swap in jeep, unless you are going to run a auto trans, way too expensive to fit it in there.

Agreed.. Keeping it simple.,keeps it affordable.

 

[justinp61]

If you're on a tight budget build a Mag.

I'm currently building a Indy headed 434 small block, in reality it should be in the 650-675 HP range on pump 93. My next engine (if there is one) will be a stroked Gen 3, for more reasons than a far better head, the block is much stronger too. Not only do the heads have superior flow, the combustion chamber is more efficient also. I know of two Gen 3s that are running in the 9s on pump 93 and neither of them are nearly as cantankerous as my 434 will be.

 

[Rodzilla]

Good read, lots of pros and cons, the biggest being $$$$$. But for me my next build is likely to be a Gen3 6.1 stroked,,,they can handle big boost, as in the 1000-1200hp kind(maybe more) with a set of turbos. And I could run 2 tunes for street and for track, with separate fuel cell for 116.
I'd never get near that with an LA/Magnum block. But this is ignoring the "what's it going to cost" factor. I have $15k into my current 605HP n/a 416 stroked 340. I don't think I would spend much more then that for a Gen3 with twins. Maybe 5k more at the most. Would be awesome to get 20miles/ gallon and later set on kill at the track. This is my future plan for a dragweek car,,,now, to win the lotto first.

 

[Infecteddog]

If you're on a tight budget build a Mag.

I'm currently building a Indy headed 434 small block, in reality it should be in the 650-675 HP range on pump 93. My next engine (if there is one) will be a stroked Gen 3, for more reasons than a far better head, the block is much stronger too. Not only do the heads have superior flow, the combustion chamber is more efficient also. I know of two Gen 3s that are running in the 9s on pump 93 and neither of them are nearly as cantankerous as my 434 will be.

I guess on the outside looking in I was never impressed by 426" supercharged gen IIIs in 4500 lb cars running with 408" supercharged Daks people whose owners talk about being over 4100lbs. I fail to see the potential in built cars running with trucks featuring as much investment in the whole project as in the car's engine.

It's far less common to see small blocks with boost like most of the faster gen IIIs have.

 

[ralphie361]

I think that in an a body especially, the cost factor and ease of installation are the main deterrents for the hemi swap. In a b body where there is a lot more space, the high cost swap parts can be avoided, but it's still not a bolt in like a magnum. I have a stock efi obd1 swap car that I complete for under a grand, including the whole donor truck! Great cruiser, good mileage (20+) highway in a c body with a 727 and 2.94s. Not fast, but not the point on that car, runs about like a stock 95 ram. I was initially going to do a 5.9 mag swap in my dart, but came upon a super cheap 5.7. I kept it stock as well, stock efi, and a 5 speed manual from a Dakota. The dart was as budget as I could do, but still way higher than the magnum, plus it would have been on the road a year sooner. I do love th hemi though, and am glad I went with it. I think it would have been hard to get the same performance from the magnum with the reliability and mileage of the hemi. I have yet to get worse than 20 mpgs in the dart, and it is a very fun driver. I'm sure I could've built a faster magnum for the same or cheaper overall swap price, but I don't regret this build. I still like and want to build more magnum powered projects because of the bang for the buck!

 

[justinp61]

I guess on the outside looking in I was never impressed by 426" supercharged gen IIIs in 4500 lb cars running with 408" supercharged Daks people whose owners talk about being over 4100lbs. I fail to see the potential in built cars running with trucks featuring as much investment in the whole project as in the car's engine.

It's far less common to see small blocks with boost like most of the faster gen IIIs have.

The two cars I mentioned are NA, no power adders, one is a 70 or so Challenger and the other is 67-69 Barracuda coupe.

 

[Infecteddog]

The two cars I mentioned are NA, no power adders, one is a 70 or so Challenger and the other is 67-69 Barracuda coupe.

Brought it up since it's the most apples to apples comparison. Boosted stroker street vehicle driven there and then back is a very valid apples/apples comparison especially when they're running similar ETs. Much else gets vague and incomparable like most comparisons people will use against any of the old motors. Many peoples' liberal definitions of stock when discussing new motors would imply that a 4.88 geared 451 stroker build with a solid roller is stock.

 

[justinp61]

Oooook, guess I missed the stock part. BTW, you can boost stock Gen 3's too, plenty of them around.

 

[moparmarks]

This is a good read. I have a 5.9 300hp crate motor that I pulled from a 71 Cuda. Found a correct 71 340 for the Cuda. Customers car. He sold me the 5.9 for 1000 and it probably doesn't have 200-300 miles on it. I drove it before I pulled it and it ran great. Could not pass it up so it's going in my 72 Dart with a 4-sp. It came with the flywheel, intake and oil pan which just sweetened the deal. Want to find a bigger cam and maybe some aluminum heads. Would like to get it up to around 400hp. Was going to slam a 440 in the dart but this sounds like a better plan.

 

[Infecteddog]

Oooook, guess I missed the stock part. BTW, you can boost stock Gen 3's too, plenty of them around.

I was just meaning level comparisons, thought what I mentioned was a pretty good one.

People often compare overbuilt N/A motors to stock boosted engines to say x or y motor is too expensive to build to run. What kills boosted motors is typically in the tune though, not the block.

The stock thing was a mild rant about more of the same of double standards on "stock". Yeah, it's always neat to see what people do with tuning to make relatively stock motors turn numbers on boost.

Reasonable builds especially of the car can do wonders and I've just not seen where the Gen IIIs have extra potential.