Intake manifold filler

[peteanddede]

Does anybody know of a good material to use as an intake manifold filler other than devcon?Thanx,Pete

[carguy2]

why would you want to fill your intake? All this would do is to reduce airflow into your motor.

[tomp40@aol.com]

use marine tex from a boat store or tractor supply sells it if theres on in your area i used devcon and it sucks. marine tex is the best

[lucky13]

When I modified my intake I was looking for devcon but couldn't find it, I ended up welding in some aluminum plates to box it all in. I figure its lighter this way, sort of. I also cut down the runners and cut down the plenum divider, gasket matched, and smoothed everything out. It pulls alot better in the Top End, and didn't lose much in the low end. Good Luck


Brian

[peteanddede]

Brian.I ended up doing about the same things you did with the intake.I removed about 1.75 inches of runner length and epoxied 2 pieces of sheet metal which I bent to fit in between the runners to the inside with JB Weld.I blended the mouths of the runners with the epoxy and later hand sanded them for a smooth transition.The ports were basically gasket matched with some material removed about .75 inches into the ports.The injector bosses were radiused and smoothed also.I tack welded a heat shield to the bottom of the manifold pan.When I removed the intake I noticed some oil residue inside on the manifold pan towards the rear at the distributor location.The pan gasket had already been changed last year by the Chrysler dealer while they were replacing a clogged cat.Any thoughts on a possible link between faulty pan gaskets and cats going bad?I know that I am not the only one who has had to change the catalytic converter.Oil being burned in the combustion chamber is not good for the cat or as an octane booster.When you installed the pan on your intake did you use any type of clamping device.I purchased some valve cover hold down clamps and am considering using these to get a better seal on that pan gasket. Pete

[lucky13]

I cut my runners down 3 inches, cut down the plenum divider 4 and welded in some plate aluminum. I also welded up a heat shield outta 16ga sheetmetal just doubled up. I made up some clamps, i guess valve cover hold downs could work too. I think that burning the oil when the plenum gasket's bad, is a direct cause of the cat getting clogged. Mine was completely clogged when i did my complete exhaust system. Iam running Hooker Headers, 3" cut out, 3" Hi flow cat (gutted), 3" 2 chamber flowmaster with turndown under the bed. So thats when i found out my cat was clogged.


Brian

[HankL]

I can understand how cutting the length of the runners would move the Torque Peak to a higher rpm where it would produce more peak horsepower.

But I can not understand how filling in part of the plenum volume with filler would improve high rpm operation - it should 'In Theory' hurt it.

With older engines with carbs, too large a plenum could cause fuel droplets to 'drop out' and wet the walls of the manifold - and it could also lesson the 'signal' of the vacuum to the carb and create a slight hesitation during acceleration.

But the Magnum manifold is a 'Dry' manifold with the fuel injectors near the end of the runners.

I think the person who started filling the plenum with epoxy (maybe Hughes) was just 'cut and try' and didn't test enough to find that the filler was not necessary.

I think the main thing is that if you cut the runner length you need to make new 'bell mouths' at the new beginings of the runners to smooth the air entrance.

[lucky13]

Magnum plenums are extremely large, especially when you cut down the runners and divider.By taking up some of that volume, resonating effects (powerful presure waves) are increased, helping low end torque. It doesn't really do anything to the higher rpm scale. Most of the magnums really respond well to this mod, most of all the v6ers. The v6s seem to have more resonation in the plenum even though they have a smaller plenum to begin with.


Brian

[peteanddede]

The smaller the plenum area,the higher the vacuum available for the map sensor.This will help trucks running long overlap cams.