Hi guys,

In making a conversion from an S-type to an F-type intake manifold, what all is involved? The S-type has the EGR hole and webbing. However, what happens with the lower manifold? Do you need to plug a hole going to the exhaust? How does the exhaust get up into the center of the intake? Without pulling it apart, it seems that there are either hoses, or pipes that will need to be plugged. Your expertise and insight would be appreciated.

Sincerely,

Rob :)

P.S. I cobbed this photo from Mr. Kennedy's site - I hope you don't mind, John!

You can either:

A: drive a plug down the EGR tower

B: use a 6.2 J intake gasket with blocked port

C: machine a circle in the EGR port at the flange and install a plug

D: replace with F engine lower intake.

E: Leave it as with the gasket in place is but unplug or plug the EGR vacuum hose


The key is to completely block the exhaust and better yet block it at the head so it does not cross over and heat the intake.

Hm, what would you use for A?

John,

Thanks for the reply. If I purchase an F-lower-intake manifold, then doesn't it still mean that there is a hole somewhere on the head (that supplies the exhaust gas) that needs to be plugged? How does one plug that?

Sincerely,

Rob :)

F complete intake turns it into a F engine except you then have S pre cups in the head still. The solid lower F blocks off the holes in the engine I'll pul mine off the shelf and shoot a pic of it.

Lee freeze plug for blocking the center from the inside is what JK was talking about

Option E will not work on OBDII S as firewall baro will see the loss of vac which becomes part of the EGR position control feedback loop after start up baro pressure is sent to the PCM and code you, for those trucks use one of the other options mentioned, or find a F PCM that doesn't look for those things that come with a EGR engine, no codes and a little more bump in performance when offroading of course.

If I purchase an F-lower-intake manifold, then doesn't it still mean that there is a hole somewhere on the head that supplies the exhaust gas that needs to be plugged?
The answer is no, the 'F' intake manifold doesn't have the EGR passages so it will block it off for you. When you take the manifold off you will see. There are 4 large holes, 1 per cylinder, and a smaller one in the middle of both sides for the EGR.

Lee freeze plug for blocking the center from the inside is what JK was talking about

Option E will not work on OBDII S


Isn't the plug burned away by the hot exhaust gasses? How do you secure it in the center hole/tube?

Option E is always worth a try, for it may work.

The cheapest way is just to buy 2 HD 'F' intake manifold gaskets with the EGR block off plates installed and put it under your 'S' intake.

Isn't the plug burned away by the hot exhaust gasses?

while it does get hot, if there is no flow through it, there will really be no chance for it to burn the plug.. think of it like a valve... if you have a valve stuck open a hair, it will burn that valve real quick... if it is seating properly it won't burn.. [plus you have a cooler air charge in the intake cooling the plug...]

Here's what you need right here Tahoe... Going for 50 bucks right now for both!
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7988999256
http://i24.ebayimg.com/04/i/04/93/cc/2c_1_b.JPG
As you can see, there is no tube in the middle like the 'S' intakes have, and the exhaust ports in the heads are blocked by the manifold itself.

Darn it TDG beat me to it, mines not for sale though since TDG got the top I shot the bottom side

Augh!

I just missed bidding on it! Thanks for letting me know, though. Anyone have a complete assembly to sell? :)

Also, thanks to you guys. I am very impressed by the selfless nature and extra effort all of you take to help newbies like me to learn about my 6.5, and to even run out and take photos of your rigs and equipment to help me understand. I am very humbled, and I truly appreciate the help.

Sincerely,

Rob :)

Wouldn't you still need to change the the S-prom out for F-prom? I've been looking to do the same on my S motor but thought you still needed to change the prom even after your swaped the intakes. Maybe to prevent SES codes from setting? The way I'm think about going was get a complete upper and lower F intake, new gaskets, and a F-prom. May cost alittle more but I'm think way easier. Any thoughts or maybe I'm missing something?

I don't think it's required in OBDI (not sure), but definately yes in OBDII as it has more sensors to be made dumb, other advantage though to swapping to F prom or PCM is F's have more agressive fuel delivery.

(There have been some communications issues on different swapped S/Fs I have tried that have coded me, sometimes PCM did not come from a setup compatible with my truck) Try the Prom or PCM 1st before converting intake system until you find a working match, or if you have the coins, it's best to just buy a reflash or prom set to your VIN.

That said, I ran my S "offroad" with F PCM for 2 years until viable reflashes were available. Early reflashes for PCMs were lame and not worth the $500+ asking price. I got my F PCM for a core for the 1st reflash I tried, as I needed ability to go back to stock config for street legal and warranty issues, found by accident the F PCM was nearly as good at the early reflash and only cost $125 vs $595 for the reflash (Z-Industries early programs).