ok..i'll try to rexlain this to the best of my knowlege.
there seems to be 2 types of turbo gaskets..
the one that i use, was developed for the MG METRO turbo engine..
the big diffrence between a turbo gasket, and a Metro turbo gasket is the fire
ring, and corrisponding block work..
as i wrote to peter the parts pimp...:
.
the true "turbo" gasket is actually rather rare. some scca guys that have 13+:1
use it. it was developed to resolve leakage problems and to resolve blown
gaskets, wich are (somewhat) common on our "A" series engines. the metro turbo
obviously had a very high CR that was resolved by this special gasket.
on Tinkerbell's 1275 (1300, 11.5:1) i was having leakage problems between 2&3.
it was machined flat and true, but i still had leakdown, and cross cylinder
lekage problems. so we decided to try one.. it worked great!...i ended up
with virtually NO leakdown (except residule through the rings)! matter of fact
this metro turbo gasket seems almost indestructable when torqued correctly.
They are supposivly reusable..(yeah right i wouldnt ) but they are indeed very
stout and wouldnt build an engine now without one. . i have 2+ seasons on the
same one, and had to retorque it (very successfully) once.
the places over here charge 200$ apiece or more.
the one i am looking to get is about 150$ (cheap)
What makes the Metro turbo gasket diffrent than a regular turbo gasket is the
cylinder fire ring on the gasket.
This ring which is normally flush on the regular non metro head gasket,
actually extends down from the bottom of the metro turbo gasket about .025" of
the gasket surface.
Some people seem to try this manually by adding a copper wire to the inside lip
of the ring. but without doing the block work.
for the Metro turbo head gasket,
a 3.080 X .025-.027 champhered groove must be cut into the top of the cylinder
wall/block upper surface to interlink and seal into this ring. the
groove/champher actually breaks inbetween the cylinders (which looks kinda
scarry but works well) after torqued down, it provides a sealing area that is
perfect.
a fellow by the name of Rick Hayes (scca fame)did my block machining.
the best price i ever got on this gasket was last year for 60 lbs (94$) and a
couple of the racers here told me they paid 180$ apiece last year. this year
the prices have gone up, and they are 90 lbs (i think)or so, something like
146$ compared to around 200+ by our USA suppliers
as far as the inexpensive, turbo gaskets go... my freind carl (mini
enthusiast)brought me one as a gift to me. it was supposed to be a "turbo" one,
but upon inspection, it didnt have the extended fire ring.
he said it was a turbo gasket, but it was diffrent than the turbo gasket i
have..
so to the best of my conclusions...
there is a "turbo" gasket..
and then theres the mg metro turbo gasket which will fit 1275's but only after
the top of the block/cylinder has been altered.
basically anyone can use whatever they want or whatever works for them. heck
some people probably have great luck with the stock asbestos/aluminum one with
no fire ring at all..
some people use a "normal" turbo gasket and have great success.
very few engines have been converted to the metro gasket. usually only SCCA
national gerenade motors.
but its worked great for mine, and i will continue using it.
i have even seen something else though...
a completely groove cut block that took o-rings and a copper wire, pressed into
the block to seal the pistons and water/oilways..really expensive..but was for
a 15:1 national grenade motor...no thanks.
*whew* i hope this is a better explination of what i know..
sorry for rambling. hope this helped..
R Kansa/RCCSA
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