ALFAGTV6.COM

kevin · Post by **kevin** » Sat Apr 09, 2005 10:51 am

After seen the superb hand made plennums on Barry's bigbore engines and JJ's(Dawie) I have made larger plennum from two 2.5 GTV plennums cut in half and seam welded up. It does not unfortunatey have the same volumes as Barry's and Dawies but it is better than before for this 3.2 GTA engine .
A few pics to follow.

kevin · Post by **kevin** » Sat Apr 09, 2005 10:56 am

pic 2

kevin · Post by **kevin** » Sat Apr 09, 2005 10:58 am

pic3 seam weld V joint

kevin · Post by **kevin** » Sat Apr 09, 2005 11:02 am

pic4 cut holes in template of runners.

kevin · Post by **kevin** » Sat Apr 09, 2005 11:06 am

Oops sorry about that. Pic 5 the 3.2 GTA engine intake runners

kevin · Post by **kevin** » Sat Apr 09, 2005 11:11 am

pic 6 need to measure the distance of runners from front to back and line up with new plennum so the hood can close. As the engine sits at angle you cant assume it will be square to the hood. Can touch.

kevin · Post by **kevin** » Sat Apr 09, 2005 11:13 am

pic7. remove cover in hood to mark existing

kevin · Post by **kevin** » Sat Apr 09, 2005 11:15 am

try again

kevin · Post by **kevin** » Sat Apr 09, 2005 11:20 am

fit new plennum. Is there more power? Dont know yet until I have remapped the Haltec after 76mm exhaust is fitted with one box.(earplugs)

Sporttunergtv6 · Post by **Sporttunergtv6** » Sat Apr 09, 2005 12:55 pm

wow!
-vittorio

rz · Post by rz » Sun Apr 10, 2005 12:11 am

nice work!!!hope this works

junglejustice · Post by **junglejustice** » Sun Apr 10, 2005 7:44 pm

Nice work....

You know, I would probably like to see more vertical height at the front of the plenum area - no room - I know) in addition to the width that you have gained here. That front cylinder (1 or 6?) starves a bit because the throttle body and associated air-intake is all of the way at the back and the thing is much higher back there, so there are some know lean issues up front as compared to the rear cylinders...

It is a non-issue on the turbo cars because the blower puts the entire plenum under pressure...

Still, nice work!

kevin · Post by **kevin** » Fri Apr 15, 2005 10:50 am

Hi JJ, you are absolutely correct as no 1 pot is still the loser here. I have thought of putting a 3.0l bonnet on as this gives me alot more vertical height for the no 1 pot, but my intention with this car was to leave its external appearences original including the 2.5 badge on the back. As this really surprises the M3 boys and the AMG mercs. Having said this the 17'' rims dont look original but my old 15'' would not fit over the the Praggia calipers.
Did you see the plennum Barry made for the 3.8l with the standard bonnet. Its got great vertical height and width but it was to difficult for me to do, so I went with what I had.
Cheers

Mats · Post by **Mats** » Fri Apr 15, 2005 1:17 pm

I don't get it, the reason for the taper on towards the front is because the cross section needs to be bigger where air to multiple cylinders are flowing, like right where the TB is, up in front there are only two cylinders so naturally the cross section doesn't have to be all that big.
Same thing in on the 75 TS plenums, taper towards the end to keep the air velocity up.

Don't be so quick to dismiss the AR engineers as idiots.

junglejustice · Post by **junglejustice** » Fri Apr 15, 2005 8:17 pm

Nope! Wrong. It has been PROVEN with individual metering that the front cylinder runs lean due to the shape of the plenum....

BTW - I don’t believe that I used the term “idiots” or even implied anything as drastic…

The taper down toward the front was for hood clearance (especially on a GTV6...)

AR also tried to address overall airflow INSIDE of the plenums by changing the internal design of the 75 V6 plenum form the GTV6 plenum... (A GTV6 plenum has stubs sticking up inside of the plenum, while the later Milano/75 style plenums have radius edge...

The big intakes on the 3.7s are opposite for that exact reason - a greater mass of air available to the cylinders closest to the intake-side.

Increased plennum volume for GTA 3.2