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Discussion Starter #1
Hi all,

Anyone done/heard of putting twin plenums (one for each bank) on a 3.0lt 24v? Apparently for more air volume?

Thanks

Victor
 

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...you mean like this...?

This is my 3.7 litre and it needs the volume...

The stock plenum is pretty good for a stock 3.0 motor however, even then - when we add the GTA cams and the 44mm GTA intake runners and the custom headers to a 3.0, we like to get a bit more air on reserve - this combination on a 3.0 really wakes them up...
 

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You could always combine these two concepts - it's been done - can't find the completed picture now - but you get the idea...

These two plenums had enlarged areas at the rear to match a 3.7 litre motor.
 

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The completed pieces can be finished to look something like this...

Imagine 3 of the runners facing the other direction and a second plenum such as this one hanging out over the other valve cover...
 

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12 valve twin turbo, I know - but this is the same concept...

A common misconception when talking intake runner-size and plenum volume is that more is better - to much and you give up power...
 

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I guess the concept is that you could essentially fill an intake runner with water and measure the volume for it (multiplied by six) and then add that to the total combined volume of the intake plenum(s)... You want to match the total displacement of the motor in reserve.

The 12 valve TT Spider above has a similar intake setup to Michael's NA 24 valve 3.7 litre documented in the following thread;

http://www.alfabb.com/bb/forums/showthread.php?t=31782&page=22

Here's one shot from it:
 

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A couple quick questions...you have another picture of the headers? I am curious to know what they look like. The other is, you most likely powder coated the air plenum and valve covers. Is that in wrinkle or satin? That is really a beautiful finish.
 

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Discussion Starter #8
Hi JJ,

Yup! Exactly! The GTA Cams u mention: They are 3.2 GTA Cams, right? Did I read somewhere in Alfa BB that you only use inlet Cams only?

Tks

Victor
 

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Well, we have our own cams made (I had problems with one set of OEM GTA on a US spec 24 valve 1995 LS - lobes hitting the heads - maybe due to the EGRs in the ' 95 heads), but any way, yeah - in essence - on the 24 valve we use what we call our GTA Stage I on the inlet as a simple first stage conversion.

By the way, GTA Stage I is a similar step to our proprietary "Group 1" cam upgrades on the 12 valvers - which in the case of the 12 valve is already a nice step above the relatively mild "S" cams!) Friends don't let friends do "S" cams! :rolleyes: :D GTA Stage II on the 24 valve cars is a good leap above that for sure, but still very street-able, idles smooth etc.

GTA Stage I passed emissions on a rolling road here in Seattle in my 1995 164 LS (Super) before AND after adding UniChip fuel and timing programmability to it! We use GTA Stage I even on the big-bore motors!

I have a set of GTA Stage II 24 valve on the way to me now - more duration and still with a stock lift, so the valves will still clear the pistons on a stock head!

Coatings; I use a ceramic coating on the intakes & headers, a NON-ceramic coating on the valve covers and yes - it is a satin finish! What headers - these...?
 

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...or these...?

(Victor, I hope that you are getting your questions answered in-between all of the other questions...) What are you working on (or are you "Vittorio" - in NY - doing the 24 valve swap?)
 

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Equal pulse and yes - longer primary, better torque...

Full-race 3.7 litre 24 valve motor needs it...
 

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Discussion Starter #13
Hi JJ,

So to confirm: You use inlet CAMS only for 3.0 lt 24 valves called "Stage II" Cams, right? Do u make the mods to the lobes yourself? As a ball park figure, how much approx to send a set of of these to Melbourne Australia? (Therefore I'm not "Vittorio" in NY!) :D

Cheers

Victor
 

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As mentioned before, the profiles that we use are somewhat proprietary. (They are not mine to post here and to simply have copied - this is after all how Dawie earns a living!) They were developed over years and years of racing (personally funded R&D.) He will discuss profiles on any cams (paid for) with buyers! Others here on the BB have posted their cam profiles, perhaps they don't mind having them copied to save a buck.

Any cams from us that you install and for some reason don't feel does what we said they would, may be returned for credit towards a more aggressive profile or towards any other modifications that we offer!

Typically though, I have had NO complaints on the Group 1 profile for a street/track 12 valve car! They offer more than a simple "S" cam and yet, they are quite agreeable on the street! We have everything up to 302-304 degrees if you must! It is just that for the street, you want drive-ability that you can't get from a profile that is too agressive.

Also, most folks want a standard lift so that they can simply add the cams to an existing engine WITHOUT rebuilding and modifying clearances to make room for more lift. In some cases these are cams cut from billet and made from scratch and in other cases they are stock cams that are welded, re-cut and then hardened (just like a factory finish.)

Our custom 12 Valve cams run 800 USD for a set of 2 cams and the 24 valve cams run 700 USD for a set of 2 cams. (24 valve cams require an exchange core.)

As far as the 24 valve cams are concerned - same story. The Stage I profile is a bit more mild as a first step addition to an otherwise stock 24 valve (2 cams on exchange.) Stage II is still an exchange deal on the two inlet cams - just a bit more aggressive. Stage III is only for a rebuilt motor - moves that inlet profile to the exhaust and brings a more aggressive profile to the inlet (4 cams on exchange!)
 

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Ok, playing around with the CBs corsa medio and some agressive profiles from catcams for my trackcar/engine.
 
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