disturbedfan121

iTrader: (5)

Ok so i am about to pick up aB6-T off a local guy for 175$ complete motor manifolds and turbo and all. I know the bottom end,(pistons and rods) are stronger than the stock 1.6.

I wanted to know if anyone has had the head and cams checked out? I'm thinking that they may be better than the stock ones because its from a factory turbo car, and i know the jdm bp-t (1.8 gtr) has better cams and bottom end as well.

So my qeustion is does anyone know the specs of the stock 1.6 cams? and has anyone had the 1.6 head flow tested before?

Braineack

iTrader: (62)

solomiata.com

disturbedfan121

iTrader: (5)

http://members.aol.com/solomiata/cams.html

thanx for the info for the stock cams brain, anyone know the gtx specs?

sn95

iTrader: (2)

i
Search miata.net or solomiata for more info on the GTX. I believe the 1.6 GTX exhaust cam was similar to stock NA exhaust cam but ground around 10* retarded which reduced overlap to about 10* (stock overlap around 20* as I recall). Simply retarding the stock exhaust cam should work too; I played around with Sport Compact Dyno last week (modeled a 1.6 with 10 psi boost and stock cams) and got the best overall power tq/hp by running the intake sraight up and the exhaust 6* retarded.

1.6 GTX also had beefier rods than NA 1.6/1.8 which fit NA motors (still may require balancing due to increased weight) and a slightly larger oil filter (which will fit a 1.6 NA).

Mitch

disturbedfan121

iTrader: (5)

neither site has much info on the gtx cams. or the whole head for that matter. i think i'll shell out the money and then give people the definite answer, hopefully it would be beneficial and not a waste lol

Braineack

iTrader: (62)

that motor had really low compression but pushed something like 20psi....im sure the profile is better suited for boost.

disturbedfan121

iTrader: (5)

Thats exactly what I'm thinking. If it is better then stock head, it could be the equivalent to a 99 head on a 94-97. except more rare lol

Zabac

iTrader: (39)

I doubt the head is any different, only the cams if anything at all as far as specs go.
A manufacturer will not make a whole new head for such a limited production run if they have something that works, they only upgrade parts that have to get upgraded, like rods, etc.
I did read somewhere that the valves were different, they are sodium filled to shed more heat or something like that.

greddymx5

iTrader: (1)

Nothing special on the b6 t except the rods and lower compression pistons...
Head is simular to the miata. The rods are heavier, reducing save max rpm
The Sodium filed valves are only found in the gtr version of the 323.

The Japanese/Austr market version of the Protege got a turbo version of the 1.8, the 'BPT' equipped GTR and GTX. The very rare GTR recieved, amoung other things, a special web stiffened block cast 'BPII', a special cast '26' head with a flow vane in the intake port and sodium filled exhaust valves!.

http://members.aol.com/solomiata/MX5Engine.html

Braineack

iTrader: (62)

Didn't the GTX rally cars make something like 250rwhp and 300tq, with 7.8:1 compression pistons? The cam profile is surely different.....i believe factory parts had to be used....


but maybe im confusing the GTX with the GTR.....which is the upgraded version of the GTX.

sn95

iTrader: (2)

The Solomiata link you referenced has basic specs for GTX 1.6 cams, you just have to understand how to read the valve events:

NA & GTX Intake valve timing:

Intake 5BTDC, 51 ABDC
5* Before Top Dead Center plus 180* (TDC to BDC) plus 51* After Bottom Dead Center = 236* intake duration

NA Exhaust valve:
Exhaust 53BBDC, 15 ATDC
53* Before Bottom Dead Center plus 180* plus 15* ATDC = 248* Exhaust duration
NA overlap = 20 degrees (period of time 5BTDC intake to 15ATDC exhaust)

GTX exhaust valve:
Exhaust 69BBDC, 1TDC
69* + 180* + 1* = 250 exhaust duration
GTX overlap = 6 degrees (5BDTC intake to 1 ATDC exhaust)

Far as I can tell Intake cams are identical between NA and GTX, exhaust cam looks like a stock NA cam ground 16* retarded (2* difference between 248 duration NA and 250 duration GTX is probably measurement error).

You can probably get the performance the GTX exhaust cam by using an adjustable cam gear on the stock NA exhaust cam. As noted in an earlier post, I did some software modeling on a 10psi NA cammed 1.6L and got the best overall hp/tq running the intake straight up and exhaust at 6* retarded. Higher boost numbers might favor more cam retard (with even less overlap)