4agte? What head to use

[510lj]

Hey everyone have just bought a 4agze with a 20v head, however its still in fwd form and still has the quad throttles on it. At the moment i have a bigport 16v in the car, now the question i have is whether i should stick with the 20v and do the rwd conversion, or should i just take of the 20v head and put the bigport head on instead.
Reasons for going bigport i can think of is, already have the rwd manifold so no need for custon airboxes/plenums, and i wouldn't have to change the cooling system. But have been told the 20v heads flow better, and if i was to keep it would the QT be hard for the tuner? and will the exhaust manifold for the 20v fit the 16?
Any advice would be great.

[70XIN]

in almost every way your bigport head is better for the application

if it were a BLACKTOP 20V it would be a different story .. but no argument here, i'd go the bigport :)

[rthy]

theres quite a bit of debate on that one, it was my understanding that even the silvertop is better in almost every way. I can't comment myself as I refuse to take a stand on things that havent been proven for sure.

[510lj]

yeh if anyone had some figures on their setup ei bigport vs silvertop that wuld be great

[Roo]

<div class='quotetop'>QUOTE (510lj @ Aug 28 2008, 08:42 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=580985)</div>
yeh if anyone had some figures on their setup ei bigport vs silvertop that wuld be great[/b]
i saw it on twincam, a car was put on the dyno switched head then on the dyno again, there was a gain with the 20v head will try find it


<div class='quotetop'>QUOTE (bazda @ Jul 7 2008, 06:39 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=440089)</div>
cos in standard form a BT head flows TONNES more than a 16v head.

I've done 16v conversion and 20vBT both stock heads with the same turbos, same ecu etc, everything is the same and hte BT will push out 40-50kw more at the wheels on the same boost :).

The silvertop outflows a 16v small port head in std form, on the inlet side about 12-15CFM more, on the exhaust side the same.
The blacktop head flows another 70CFM more on the intake! and the exhaust flows 50CFM more than the silvertop!"[/b]

[BluTrueno]

i have standard bigport running 7psi and it dynoed at 170-180hp at the wheels.

Thats with razorback ecu, gtr injectors, daewoo coils, hks air filter oh and turbos a t3 off an r32

Maybe if someone else has similar mods with silvertop would be a good comparison but atleast that gives you an idea of bigport power.

[70XIN]

but with the 20V you'll have to muck around with waterlines/dizzy, as well as make a custom plenum

ST *might* flow better, but it sure isn't a better (sensible) option in this case..

[510lj]

thanks blutureno, ill be running basically exactley what youve got.
70XIN yeh thats the thing I'm battling with at the moment, the easeir option is the bigport, but thought id get all the info i can before i put the engine in.

[balistic]

From other discussions I've read on this topic, the extra mucking around and $$ spent for the ST head on 4AGTE is not worth the possible small gains to be had over the bigport head, unless your going all out with the build.

[Vezza]

<div class='quotetop'>QUOTE (HighLife @ Aug 29 2008, 09:22 AM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=581119)</div>
From other discussions I've read on this topic, the extra mucking around and $$ spent for the ST head on 4AGTE is not worth the possible small gains to be had over the bigport head, unless your going all out with the build.[/b]


Yep, that is true... if you were "buying and installing" a 20V head onto the GZE. But since it's already there setup to go, I reckon he may as well keep it as and just do the RWD conversion. May as well spend the effort (not much) to do the cooling conversion rather than swapping to a "lesser" head IMO.