diferent between 7a and 3b head

[aronmatic2]

hi guys

i have 7a head. can i install to my s2?
what is the diferent between 3b and 7a. i only know about camshafts.
what else?

[PekkaS]

I swapped 7A manifold to my ABY and it required few new holes to fit water manifold (or water collector, as etka says). Also I had to make a place for hall-sender, but that´s not required when it comes to 3B.

[S2central.net]

Turbo heads have sodium filled exhaust valves. The 7A doesn't.

Pekka is correct about the hall sender mods (except on 3B).

Paul

[aronmatic2]

ok

if i change the exhaust valves, i can install the head? that sounds good.
thank you guys.

[Albert]

what would be the advantage for using 7A head than 3b/aby ?

[porkkis]

Availability.

[Floddy]

AFAIK the cooling canals (is that the correct term?) are different.

[4WheelDrifter]

It's normal for a turbo head to have larger cooling chambers. A 7A head may give more scope for porting and combustion chamber enlargement.
Has anybody got any old 3B, ABY, 7A heads to section?

[mcandmar]

I've had a chance to compare my 7A to an ABY head side by side, as said only the water manifold differs in that it has outlets from the head between each cyl, where as a 7A only has the one outlet in the middle of the head. And also the Hall sensor mount. Mount for the distributor is also there on an ABY with a little cover bolted over it. Other than that they are the same.

Mark.

P.S. 7A engines DO have sodium filled exhaust valves, not just the turbos.

hi guys

i have 7a head. can i install to my s2?
what is the diferent between 3b and 7a. i only know about camshafts.
what else?

[aronmatic2]

what would be the advantage for using 7A head than 3b/aby ?

i have a 7a head in my garage. i have a 3b head on my car with wery bad porting and polishing. we want to port and polish the 7a head, change the valves for srick cooled valves.and when we have done, change the head and the car not going to stay for a week or two.

my car going very nice. what you guys think about low compression engine.
i have 9. what boost is recommended.

my mods:
tt pistons
factory s2 conecting rods
rs2 injectors,ecu
11,5mm lift camshaft
home made EM
s4 IM
lancia exhaust valves
kkk k26/27 turbo
large cooler
s6 6 gang trans

i am planing to buy a garrett gt30r

[Beetie]

i have a 7a head in my garage. i have a 3b head on my car with wery bad porting and polishing. we want to port and polish the 7a head, change the valves for srick cooled valves.and when we have done, change the head and the car not going to stay for a week or two.

my car going very nice. what you guys think about low compression engine.
i have 9. what boost is recommended.

my mods:
tt pistons
factory s2 conecting rods
rs2 injectors,ecu
11,5mm lift camshaft
home made EM
s4 IM
lancia exhaust valves
kkk k26/27 turbo
large cooler
s6 6 gang trans

i am planing to buy a garrett gt30r

Best speak to Mihnea, he can give you alot of advice for the turbo spec....

[4WheelDrifter]

Here's an extract from the 7A Manual to show that the exhaust valves are sodium filled.

[aronmatic2]

thank you.
anyway, i will change the valves because i have them.
another thing. how can i installk the water collector?
do i need it?

[S2central.net]

7A exhaust valves are different from 20VT exhaust valves - at least they were last time I looked on the family album.

[AnLe]

7A exhaust valves are different from 20VT exhaust valves - at least they were last time I looked on the family album.

Yes they are, they have different part numbers.. I have witnessed +140hp per cylinder powers with these na-valves, no prob.

please keep in mind that nm/7a/gtigolf has very good power per litre ratio considering the mid 80:s.

It is allways assumed that turboparts are better than na versions, but how is this: turbo has around 9 compratio, na has 10.5 and with 0.7 standard boost pressure the turbo engine is "9.7" versus 10.5 of na engine and factory margins the 7a valves should be better..