Frankenplenum
 

Several years ago I bought a plenum from phrogs that was missing the MAP sensor ears. I Siamesed that the Inj housings and the heads....with small intake cams(222 .415 primary/236.425 secondary) I made 441RWHP/7100RPM; that's untuned.

Since then I ported the inside of the plenum removing all of the water passages and guts(There are significant blockages to the #1 and # 2 intake ports, etc. Added a 63MM TB.....

I decided that now I am going to add volume to the plenum; I will be cutting off the roof unshrouding the runners adding an inch, and cutting the bottom off and doing the same.

I am also going to do some air intake testing.....I know people say there is nothing there, but I want to try a few ideas.

Here is where I started with the Siamese
http://i134.photobucket.com/albums/q...f/DSCN3804.jpg

Re: Frankenplenum
 

Sounds like an interesting project, Lee.

Have fun and Good Luck.

Re: Frankenplenum
 

The LT-5 Plenum is know to be too small.....on a manual trans car you really want at least 1X the CI of the motor, some say 1.5X. I also know that in testing larger plenums did better during engine development....approximately 55-80 additional cubic inches are needed.

A lot of people told me the plenum roof would not clear the hood, however I have 1.14inches in the front and 2" in the back. I think the issue is raising the entire plenum and not just the plenum body....the runners might hit the outside of the raised section of the hood; but the plenum box has room...I also have no AC.

I would like to have unshrouded the #7/#8 runners but the fuel rail is a challenge

Re: Frankenplenum
 

I like it when someone tries to do what others say they shouldn't.

Re: Frankenplenum
 

Lee, keep in mind the engine twists when you accelerate, it will lift one corner. Sounds like you'll be real tight. I like where you're headed with this. MORE POWER wuh-wuh-wuh.

Re: Frankenplenum
 

A High Rise Hood would solve some of the height issues.

Be interesting to see what could be done.

Keep Us posted, and We like pictures.....

Re: Frankenplenum
 

Interesting project. I've been pondering something similar; thinking about using a split air box, vis a vis the Coyote's "Y" approach and straightening the runners; reducing that (90º) bend into the IH. (I believe it was Grahm (?) that said they were able to increase the 90 LT5 output to something well north of 430 chp by straightening out those runners some, IIRC. But, anyway, let's face it: GM isn't going to be coming up with anything for the LT5s. It's up to us ZR-1 loyalists to do it. And, so learning from what others are doing with the DOHC motors is a good place to take notes, I recon!:cheers:)

Re: Frankenplenum
 

Put some silly putty under the hood and see if it touches anywhere.

It might hang on long enough haha

I remember that plenum.
Pretty sure it came out of tommy morrisons stash

Re: Frankenplenum
 

Way ahead of you phrogs, nabbed my daughters playdo and checked it...put the enture can shape on the plenum and dropped the hood. lots room

Re: Frankenplenum
 

Lee:

What about those people who put on the phenolic plenum spacers some years ago complaining about rubbing holes in the hood?
If I recall correctly, those spacers were only 1/2 inch or so, surely what you've got planned will need more room than that.

'Crabs