I am wondering if any of the Mopar intake setups will allow me to eliminate the plenum pan.

I currently run the stock kegger with a hughes plate (and metal gasket) but everything I'm experiencing tells me that I have a vacuum leak. I will likely pull it in a week or two for inspection and cleaning but might hold off if I can find a replacement / upgrade for the intake.

I suspect the answer to this question is within the plenum thread, but I haven't found it yet. If it's one of those "beat to death" topics I apologize, but would like a link that leads to this topic.

Thanks!

Will Bass

 

What makes you thing you have a vac leak? How did you secure the bolts to it? When i did mine i used lock tight and lock washers on the bolts to make sure they didn't back out. Did you use felpro gaskets or crappy ones Hughes gave you with it? The M1 intakes are a one piece design.

 

Engine is really bogging down on acceleration and idling rough at lights. The truck is getting horrible gas mileage (down from 16.5 to 11.5) and setting off random misfire codes. No pinging like the last time and very little oil consumption but it drives like the computer is trying to dump fuel in the chambers to compensate for a vacuum leak. I pulled the upstream oxygen sensor (Delphi brand) to see if the cat was shot but it made no difference in driveability.

The cylinder heads were replaced about 10,000 miles ago, before which I replaced every single sensor in the vehicle chasing a cracked internal head passage. I threw in new plugs, brass rotor and cap, coil, good wires, etc., and routed them as per the TSB.

At the time of the head replacement I did not install the intake manifold myself, but suspect a plenum issue or related vacuum leak, possibly where the front and rear gaskets mate with the manifold. I seriously doubt that the metal Hughes gasket was RTV'ed. Likely the plenum pan bolts were reused.

I will hook my vacuum gauge up to the manifold and look for any fluctuations at warm idle and under load but were it that I have to pull the manifold again I am considering an aftermarket manifold that permanently eliminates this weak spot on the engine. But if I decide to reuse the kegger I will certainly review the plenum thread in detail!

 

The Mopar Performance intakes, both the M1 2bbl and M1 4 bbl have been discontinued, hence they are REALLY hard to find.

 

And really expensive even if you can......

 

And why most go to the lesser Hughes which is still available but still $$$$

 

I've never understood that... Hughes' own dyno chart shows the keg to be superior up to almost four grand and about equal for horsepower from five grand on. The Hughes holds its torque curve longer, 'tis true, but in a three ton truck you're probably better off with the keg's massive low RPM torque advantage.

Just thinkin' out loud here: If the IAT relocate is good for the five or so WOT horsepower (from memory) that it's claimed to deliver, then the manifold swap accounts for just that much less gain on the dyno curve. Hmmm...

 

I'm leery of going back to the Hughes folks--they don't seem to enjoy the best reputation around here!

I have no idea if this is actually available, and while it's not the high-rise looking M1 that I returned to Mancini Racing a few years ago, if it's a one piece intake I might seriously consider it!

 

On an otherwise stock truck. If you have any hopes of making any real extra power the stock keg cannot support things like higher lift cams, higher flow heads, or boost. Great for a stock truck engine and something of the style I personally wish the big 3 would continue using on these higher power trucks to maximize the tq but wholly useless on anything where performance is the desire.


IAT relocate is, in my personal opinion (yes opinion, you know what they say about that), a waste of time. All it does is slightly richen your a/f ratio. Tuning can do the same thing and manage it better. However on a mostly stock truck, again, there's nothing wrong with it.

 

The one they have pictured isn't EFI for one.... and if you double check the part number it's the 4bbl m1