I have a 6.5 naturally aspirated engine that I recently put into my '75 pickup. I'm addressing this question to the 6.2 forum because the folks on the 6.5 forum generally assume you have a turbo.


I'd like to improve my air intake. I'll probably figure out a low cost way to modify the factory system. I've gotten some good ideas by searching this forum. I'm wondering whether I can just remove the EGR unit that sits on top of the intake manifold. I don't have it hooked up to anything. It will expose a circular hole in the very center of the manifold between the two half moon shaped ports that lead directly to the heads. Where exactly does this circular hole connect to? Is it okay to expose it? Will it improve performance?


Thanks for the help

There are small exaust ports that connect to it, hence EGR (Exhaust Gas Recirculator).


Removing that vacuum activated valve would let exhaust pour into you intake manifold all the time, reducing power and performance and making you air filter a real mess(trust me, I've tried it).


The EGR system on a diesel was an emissions idea that really didn't work well and hindered the power.http://www.dieselplace.com/forum/smileys/smiley11.gif The best thing to do would be to get an intake manifold off a mid 80's 1 Ton VIN J 6.2L(didn't have EGR system) from an autowreckers and install that. It will bolt right up and get rid of that center hole giving your engine better airflow by making the two half moon holes bigger. More air in = more power out.http://www.dieselplace.com/forum/smileys/hihi.gifEdited by: project 6.2L

Thanks P6.2, That makes sense of course since the inside of that hole looks like an exhaust pipe. Are you sure that the manifold you mention will fit a 6.5L? That would be excellent if it did. In the meantime, what do you suggest I do with the small hose fitting on the EGR? It's not connected to anything right now. That was how it was set up in the truck I got the engine out of. Can I plug it off?


Thanks

i'm not familiar with the design of the manifold but some on the 6.5s have cut out a plate the size of the mounting flange on the egr then reinstalled the egr over it putting the gasket between the plate and manifold. blocks it off and still looks legal if you cut it pretty.

Use 18 ga sheet metal thick enough to hold pressure but not so thick it's obvious, not that I would know anything about disabling EGR setuphttp://www.dieselplace.com/forum/smileys/smiley2.gif

Is this better than getting a non-EGR manifold? There's one on Ebay that I have my eye on. It's out of an '85 6.2 Suburban I think. Will it fit my 6.5 heads?


Thanks

Not 100% sure but the block hasn't changed drasticly from 6.2 to 6.5 other than cylinder bore especially with the N/A 6.5L so I wouldn't see why it wouldn't fit. If it looks the same chances are it is the same as the 6.2L.


The advantage to going with the EGR-less intake is the better airflow. Making a plate will work but you won't get the airflow increase.


There is a little hose that is usually hooked up to a solenoid that controlles the vacuum that opens and closes the valve at specified throttle positions. Just get rid of the hose and leave the fitting unpluged and block off the hole in the aircleaner(not critical but good idea). The valve will stay closed. There isn't enough exhaust pressure to open it since it is spring loaded.


My personal opinion (for what it's worth) go with the EGR-less intake.Your engine will run a little more efficient.Edited by: project 6.2L

If you're going to shell out some bucks for an EGR less manifold get the 6.5L "F" engine upper/lower manifold.

Depends on where you are runnning the vehicle, if someplace where emission equipment is looked for the shim plate is a viable alternative, hog out the upper intake like in my IC install web link and you will have virtually same airflow, I don't have any problems flowing mine.


http://myweb.cableone.net/tbogemirep/ (http://myweb.cableone.net/tbogemirep/)

I got the non-EGR manifold. I plan on installing it and modifying my air filter assembly when I get the time. I'll post when it's done.


Thanks for all the help

Would be wise to match the intake to the 6.5 heads. Old intakes don't quite match the ports of the newer engines. That would only be necessary for absolute best performance. If it's worth doing, it's worth doing right.

Diesel Pro,


Can you elaborate? Do you mean that the manifold I got won't work, or does it need to be modified somehow in order to match?


Thanks

I believe he was reiterating what I said. If you're going to shell out some bucks for the EGRless manifold get the "F" engine manifold. I would research it on www.car-parts.com (http://www.car-parts.com) 92-00 lower manifold is the same. The 94-00 upper has electronics on it, not that it won't work. The "F" engine is any true 3/4 or 1 ton with eight lug axles.

I welded a plate on my EGR mounting bracket. I also put solid intake manifold gaskets on my engine as I didn't want the exhaust gases cross feeding from the exhaust manifolds. I also cut out the butterfly valve in the left side exhaust manifold.


The heavy duty 6.2L engine did not have an EGR or the butterfly. The heavy duty engine also had a higher output injection pump which I installed when my first injection pump failed.


I have about 230,000 miles on my engine and it still puts out maximum horsepower and minimum smoke on a dynometer.