ok ive decided to try something ive wanted to for over a year now.....someone told me back in our festy days that a miata exhaust cam yeilds a power gain on our engines... i was skeptical and passed it off ... yet with russ camming the super roo it has come back up....
ive got a couple friends that have turbo 1.6 miatas and there cars build more power per psi than the b6t. i allways passed this off as the engine having a higher CR.... when i built my engine with the b6 n/a block i figured id be alot closer power to pressure...
with new events ive started researching again
first what caught me was the N/A 1.6 b6-ze makes 115hp stock where a stock capri N/A makes 100 even... so i started calling friends and low and behold my buddy nate has a 1.6 miata tore appart all over his garage... cams sitting out of the head soaking in a oil bath....Handy... so i grabbed a set of b6t cams and started comparing
first noticeable difference were the markings
the b6t uses b660 cams intake and exhaust...
the miata uses a b660 intake cam and a b61p exhaust cam... hmmm so i did some more digging..
b660 intake and exhaust on the b6t
b660 intake and b61p exhaust on the b6ze (miata)
now, all b660 cams weather intake or exhaust are identical (exception being the intake has a slotted drive end to run the dist.)
so i researched and came up with this nice little chart off solo miata ...
1990-93 5-speed
Dur @ intake exhaust
Adv. Dur.
(.003") 236° 250°
.010" 220° 233°
.020" 210° 223°
.050" 192° 204°
.100" 170° 180°
.150" 147° 156°
.200" 122° 130°
.250" 90° 97°
.300" 37° 42°
Valve Timing 5° BTDC
51° ABDC 53° BBDC
15° ATDC
Overlap. 20°
Base circle Diam. 1.3"
33 mm 1.3"
33 mm
Total Lift
.309" 7.86 mm .311" 7.9 mm
now on the right is the b660 cam or intake on a miata and both on the b6t... on the left is the b61p mystery exhaust cam...
as you can see the 1p cam has a longer duration (250-236)and higher lift(.311"-.309") than the 60 cams do...hmmm
to be continued.... this weekend i will be installing the b61p cam into my high compression turbo build....we'll see how it works....