Magnum engines, any one mess with them

[JOES66FURY]

I need to pull the intake off the truck to replace the plenum gasket...I thought that while I am at it...I might be able to squeeze a little more grunt with a cam....but I dont want to screw anything up with the emissions and what not.....anyone have any suggestions...is it worth the effort? I understand the heads are the real cork on these motors. I pull a trailer and haul stuff and do some trail riding...so something that will offer a little low end grunt...I could even go with different rockers to...I dunno, the engine is such a dog that it is just not that much fun to drive...

[DanStokes]

Re: Magnum engines, any one mess with them

My understanding is that the heads are supposed to be better than the old ones with the dogleg in the middle exhaust ports but I don't really know that for sure. My 318 (5.2 really) in the Dakota is pretty peppy - but I'm pushing a lot less weight. I also have the factory towing package with the lower rear gear (I forget the ratio but it's lower by a bit) so maybe that's why it feels better. Anyhow, I'll be watching this thread to see what folks have to say.

I'm sure if you call Comp they'll have an emissions-friendly cam with a bit more poop. Maybe Scott knows if there's much to be gained with a computer tweak on these. So we'll see.

Dan

[min301]

Re: Magnum engines, any one mess with them

My understanding is that the heads are supposed to be better than the old ones with the dogleg in the middle exhaust ports but I don't really know that for sure. My 318 (5.2 really) in the Dakota is pretty peppy - but I'm pushing a lot less weight. I also have the factory towing package with the lower rear gear (I forget the ratio but it's lower by a bit) so maybe that's why it feels better. Anyhow, I'll be watching this thread to see what folks have to say.

I'm sure if you call Comp they'll have an emissions-friendly cam with a bit more poop. Maybe Scott knows if there's much to be gained with a computer tweak on these. So we'll see.

Dan

Dan is correct...it's the intake that's a restriction, or so I've heard.

[BBR]

Re: Magnum engines, any one mess with them

The heads are actually fairly decent for a factory head (~215 cfm at 0.500"). It's the tiny stock cam, weak stock valve springs coupled with the beer barrel intake that are the restriction.

You might poke around here and see what these guys are running:

http://www.dakota-durango.com/forum/index.php

[JOES66FURY]

Re: Magnum engines, any one mess with them

I know that the intake sucks but according to the info I have read over the years the heads are the next weak link.

The truck is a 1/2T 4X4 360 with the factory towing package so the rears are a 3:91 the tires are 35".

I have been over at Hughes engines and they have a whole list of things to change but the cam prices are fing insane. they want you to buy a core and then the custom grind it...then payfor the custom ground cam...the intake prices arent much better, they have a modified E-brock intake now that is supposed to do amazing things..up top..not down low where I want it...they also have modified "barrel" intakes that shorten the runners and move the power band up...again..not where I want it. Oddly the trans shifts right when the engine would really start making power with the more modified intakes. The prices are insane too, on all their parts. I guess becasue they are the only ones that really make parts specific to the magnum engines.

So, my thought was...SOMEONE has to make a cam that will give me a little more grunt out of the hole at a less than bank breaking price.

[BBR]

Re: Magnum engines, any one mess with them

Another good site:

http://www.bionicdodge.com/bionic/index.php

Any cam for a Magnum is going to be a hydraulic roller and they treat them as if they are made from gold.

Your other option is a regrind from some place like Delta cams: http://www.deltacam.com/

Last time I checked, a regrind was VERY affordable, like less than $100. You might pick up a junkyard cam, send it off and have it ground to your specs.

For comparison's sake, a stock E7 Ford cylinder head (EFI 5.0L Mustangs) only flows a little over 150cfm at 0.500".

FWIW, several magazine articles have made 400 hp with stock magnum heads.

[DanStokes]

Re: Magnum engines, any one mess with them

I'll second Delta Cams. They aren't the best at recommending a grind (although they'll try hard to be helpful) so if you call 'em with the specs you want they can do it for you. My cams for the six were $100/ea on a new blank and they will be cheaper if you can provide a blank to them. Really nice folks and VERY helpful. AS I recall there's no extra charge if it's a roller. No clue on intakes, etc. Maybe Extrude hone?

Dan

[JOES66FURY]

Re: Magnum engines, any one mess with them

When I get back inot town I will check them out...I can take the spec's from Hughes and have one ground. As far as the intake goes...I may be able to istall a shift kit to tweek the shift points a little...and modify an M1 to fit my needs...I have seen it done...just need to drill and tap for the injectors and install an adaptor for the throttle body...might score one cheap off ebay or craigslist...if I purchase everything from hughes it will cost well over 1500 bucks...and I dont know that the HP increase will be worth it.

[Matt Cramer]

Re: Magnum engines, any one mess with them

IIRC, that 380 hp Mopar 360 crate motor used stock Magnum heads. Takes a while for the heads to be the bottleneck. A single plane intake, cam, and proper tuning can wake them up.

[Aircooled]

Re: Magnum engines, any one mess with them

The LA Magnums were nice engines for the early 1990's. My 94 regular cab / short bed Dakota with the 5.2L, 5spd and 3.91 gears ran 14.9@92 on Radial T/A's with only the Mopar computer and a K&N.

Nobody that has seen the stock cam specs would think the heads are the restriction. The 1995 5.9L cam is 250* advertised at .400" valve lift. That is something like 195* at .050". Cam is so small that it is installed 3* retarded just to get the engine to rev to 5200 RPM.

Mopar sells the computer compatible Magnum R/T cam, but it's still only 205*and .460" lift. The engine needs a cam several steps larger, but the stock Speed Density computer can't handle it.

The real hurdle with the LA Magnums is the computer. It's Speed Density, so it needs to be re-tuned after any significant hp increase. However, it's apparently a fairly closed architecture so there is only a couple of places that can do it.

[JOES66FURY]

Re: Magnum engines, any one mess with them

The LA Magnums were nice engines for the early 1990's. My 94 regular cab / short bed Dakota with the 5.2L, 5spd and 3.91 gears ran 14.9@92 on Radial T/A's with only the Mopar computer and a K&N.

Nobody that has seen the stock cam specs would think the heads are the restriction. The 1995 5.9L cam is 250* advertised at .400" valve lift. That is something like 195* at .050". Cam is so small that it is installed 3* retarded just to get the engine to rev to 5200 RPM.

Mopar sells the computer compatible Magnum R/T cam, but it's still only 205*and .460" lift. The engine needs a cam several steps larger, but the stock Speed Density computer can't handle it.

The real hurdle with the LA Magnums is the computer. It's Speed Density, so it needs to be re-tuned after any significant hp increase. However, it's apparently a fairly closed architecture so there is only a couple of places that can do it.

So, I can my the mopar performace computer right?

What do you recomend I do to this thing to kick it in the ass...it is such a MF-ing dog...the 4:11 grear swap doesnt seem to do much form the guys I know that did it....

[IRONHEAD]

Re: Magnum engines, any one mess with them

^^^^^^^^^^^^^^^^^^^^^^^^^^
loose the mudder tires..
4.11 gears don't have the same affect on tires that large... that why the guys you've talked to. didn't get much out of it..
before you even get ideas in your head. might want to do a leakdown and commpression test..wet and dry..
i'd leave well enough alone... it's your daily..
spend the time and parts on the car that .changes will make a difference..
it's a big tire 4 by 4..
the drivetrain eats a ton of power..
whatever you do. your not gonna see much,
as the drivetrain will eat most of it..

[JOES66FURY]

Re: Magnum engines, any one mess with them

Meh, if you wheel at all you know that power is your friend..and if you tow..say...a 24 foot trailer...power is your friend...and if you drive a dog every day..it gets old....

Leave well enough alone?...HA!, that crazy talk man...just crazy talk

Point is..I aint looking to set a speed record..but I do want to make some more power for towing, wheeling and daily driving

The intake has to come off as does the timing chain cover due to leaks...I am half way there at this point so why not see if a cam change can wake the motor up a bit....

I would have to go to a 4:56 gear in order to see production performace with my 35" tires....The rear is a 3:91 and it came with about a 30" tire...now that it runs a 35" tire I need to increase gear size substantialy in order to see real performance and gas milage gains...the 4:11 change is not big enough to see any gains that make it worth while. s

I suspect that a large gear change would be the most benificial to me but if I have to pull intake and chain cover...well...

[IRONHEAD]

Re: Magnum engines, any one mess with them

open can of worms at own risk

[DanStokes]

Re: Magnum engines, any one mess with them

Great info on how mild the stock cam is. If mine gets to where it I have to take the motor apart for some reason it'll get a better cam for sure.

Aircooled - who can tweak the speed density properly? Sounds like the way to go. Is the MOPAR magnum 'puter any better for tweaking or is it just as "protected"?

Thanks
Dan