5,2 Magnum... Plenum and other things to look out for.

Posted By: hp383

5,2 Magnum... Plenum and other things to look out for. - 09/19/12 03:47 AM

I recently picked up a 92 Dakota with a 5.2 Magnum.

I know (vaguely) of the plenum issues, but not the best solution to repair.

What are the suggested parts to use on this, and do I fix it now before it goes bad, or if its lasted this long, no worries?

What other issues might these be know for? And best solutions to avoiding trouble?

Posted By: goldmember

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/19/12 04:19 AM

Check for an oil pool in the intake manifold before you start wrenching.The plenum gasket is a known failure point but you have options. Replace the gasket and go. buy a replacement plate or make your own. I choose number 3 as for $10 and an hour I can make my own plate and be done with this issue.

Posted By: 70Cuda383

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/19/12 04:25 AM

Or if you're going to start modding the motor, start with the intake and buy an M1 and never worry about a plenum gasket again

Posted By: coronet1966d

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/19/12 06:26 PM

M1 is garbage

Posted By: jbc426

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/19/12 07:08 PM

I'm working on freshening up a 2001, 90k mile 5.9 Magnum to replace the Slant 6 in my 1968 Barracuda convertible. I got a different cam, springs, retainers, valve seals and timing set from Hughes Engines; and replaced the rod bearings and front and rear main seals while it's on the stand.

Eventually, I will put in a stroker kit and upgrade the heads and intake, but for now I picked up Hughes's plenum repair kit with all the gaskets hose etc. I gasket matched the intake ports in the heads and intake and modified the internal runners in the stock beerkeg manifold as done on by the guy in this link. Mine didn't have the center divider so it was quick and easy.

http://dodgeforum.com/forum/2nd-gen-ram/145873-kegger-intake-mod-diy.html

I'll have some more questions too for those who have tread this path before with the whole fuel injection hook-up and reflash along with the 45rh surgury/ swap etc.

I blame Steve aka Autoxcuda (as seen here at Spring Fling a few years ago) for instigating this latest series of upgrades....He was just having too much fun with that car of his down at Mopar day at Willow Springs, which by the way , they are doing again this year before Fall Fling.

Attached picture 7386027-IMG_1835(Large).JPG

Attached picture 7386027-IMG_1835(Large).JPG

Posted By: 360view

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/20/12 01:35 PM

Quote:

http://dodgeforum.com/forum/2nd-gen-ram/145873-kegger-intake-mod-diy.html

I have long wondered if instead of cutting off some of the length of the stock beer barrel
A hole could be added part way down the runner instead.

The air would then decide
Which inlet to enter.

Don't laugh about
"the air deciding which path to take"
Because Ford engineers found that actually happened
And they eliminated an internal runner flap valve
That had been designed into their original intake manifold design.

The Magnum V8 total runner length
which combines
manifold runner
plus length of the cylinder head intake port up to the backside of the intake valve
is said by Long time Chrysler engineer
Willem Weertman
to be 18 inches,
And appears to resonate in the 3400 to 3600 rpm range
Which makes sense
If you look at the 1992 Magnum 5.2 rpms of max torque and max horsepower.

http://www.amazon.com/Chrysler-Engines-1922-1998-Willem-Weertman/dp/0768016428

I quote the
18 inches by Weertman
Because it is hard to know how to measure it yourself
... Do you measure
the top, middle or bottom
of the quite rectangular runner passage as it makes its arching path?

A Magnum being set up for acceleration
Needs resonation in the 4600 to 5000 rpm range
With header lengths to match.

The towing duty iron V10 had 25 inhes which allowed resonation at 1700 rpm.

My fuzzy memory is original 5.7 Hemi was
27 inches
but I dont know the current 2013 dual path lengths.

Posted By: 70Cuda383

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/20/12 01:37 PM

Quote:

M1 is garbage

Really? Why is that your opinion?

Posted By: jbc426

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/20/12 03:01 PM

Quote:

Quote:

http://dodgeforum.com/forum/2nd-gen-ram/145873-kegger-intake-mod-diy.html

I have long wondered if instead of cutting off some of the length of the stock beer barrel
A hole could be added part way down the runner instead.

The air would then decide
Which inlet to enter.

Don't laugh about
"the air deciding which path to take"
Because Ford engineers found that actually happened
And they eliminated an internal runner flap valve
That had been designed into their original intake manifold design.

The Magnum V8 total runner length
which combines
manifold runner
plus length of the cylinder head intake port up to the backside of the intake valve
is said by Long time Chrysler engineer
Willem Weertman
to be 18 inches,
And appears to resonate in the 3400 to 3600 rpm range
Which makes sense
If you look at the 1992 Magnum 5.2 rpms of max torque and max horsepower.

http://www.amazon.com/Chrysler-Engines-1922-1998-Willem-Weertman/dp/0768016428

I quote the
18 inches by Weertman
Because it is hard to know how to measure it yourself
... Do you measure
the top, middle or bottom
of the quite rectangular runner passage as it makes its arching path?

A Magnum being set up for acceleration
Needs resonation in the 4600 to 5000 rpm range
With header lengths to match.

The towing duty iron V10 had 25 inhes which allowed resonation at 1700 rpm.

My fuzzy memory is original 5.7 Hemi was
27 inches
but I dont know the current 2013 dual path lengths.

Kevin over at at Hughes was telling me they've done a lot of flow bench testing with the beer keg manifold in the past. They found that every inch removed from the runners raises the resonance peak about 200 rpm.

He told me gasket matching the the intake and head would probably give me a noticible power increase, more so than any other mods inside the manifold including cutting the runners back as shown in the link.

Regarding cutting another opening to the port. It may work, who knows, but it seems like it would interupt the flow and reduce the velocity of the exsisting air flow in the port causing turbulence and slower flow.

Posted By: coronet1966d

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/20/12 03:40 PM

the only gains found on this intake are above 4000 RPM and if you have a dakota,ram,durango they redline at 5000-5500. 1500RPM of top end gains dont outweigh the torque losses down low. on one my dakota street driven the stock keg intake is alot more responsive not to mention the M1 costs a fortune

Posted By: 70Cuda383

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/20/12 10:09 PM

Quote:

the only gains found on this intake are above 4000 RPM and if you have a dakota,ram,durango they redline at 5000-5500. 1500RPM of top end gains dont outweigh the torque losses down low. on one my dakota street driven the stock keg intake is alot more responsive not to mention the M1 costs a fortune

Ok. sure. an M1 all by itself, with no other mods, isn't really worth the cost of the intake. However, there isn't really any low end loss. when your motor makes more torque than the tires can hold, it doesn't matter if your making 300 ft lbs or 350 ft lbs...when the tires break loose, anything more is wasted in smoke.

regardless, look at my post--re-read it. I said "if you plan on making other mods, then start with the intake now"

Posted By: fox

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/21/12 04:23 AM

You should also check the bolt length on the plenum. Two of my trucks has leaks and when I removed the intake, I found they had already replaced the gasket.

BUT, I found thewashers still spun freely on the bolts. The bolts were tight, because they bottomed out in the holes!!!
Both trucks were repaired by dodge dealers!

Posted By: coronet1966d

Re: 5,2 Magnum... Plenum and other things to look out for. - 09/21/12 12:34 PM

Quote:

Quote:

the only gains found on this intake are above 4000 RPM and if you have a dakota,ram,durango they redline at 5000-5500. 1500RPM of top end gains dont outweigh the torque losses down low. on one my dakota street driven the stock keg intake is alot more responsive not to mention the M1 costs a fortune

Ok. sure. an M1 all by itself, with no other mods, isn't really worth the cost of the intake. However, there isn't really any low end loss. when your motor makes more torque than the tires can hold, it doesn't matter if your making 300 ft lbs or 350 ft lbs...when the tires break loose, anything more is wasted in smoke.

regardless, look at my post--re-read it. I said "if you plan on making other mods, then start with the intake now"

ive got an M1 for sale as soon as i take it off my truck

hughes FI air gap