O-Ringing an inlet manifold gasket.

[roadsailing]

what about using a rubber o-ring in the groove? that cant squeeze out into the port, and you could stick some RTV in there for good measure. o-rings will take a compression et eventually, but would be easy to replace etc.

[oldcorollas]

can't squeeze out, but can be sucked in!

nitrile eventually changes shape, but usually cos they are exposed to heat.. and they can really only take 100deg, and still break down over time...
Viton or kalrex? or silicon should maintain shape...

[30psi 4agte]

I rang around to a few places today (gasket manufacturers) And i was told that urethane s out of the question as it wont handle the heat.

after giving the the guy a through run down of my situation and the type of setup i have he suggested that a fibreous type gasket was my best option and the thinner the gasket the better.
He suggested some graphite / grafoil material will hold 40 psi no prob.

Im just starting to get abit confused with what to do now !!! I thought this stuff would surely blow out but i have done some research on the material and in its non re-enforced (no steel in between) form it will hold 1900 psi.

[Matt-AE86]

Arrrrrr Teeeeeeeeee Veeeeeeeeee

[oldcorollas]

the graphite will nto break cos it is fairly strong.. unless it cracks...
but, being strong, means it doesn't deform much so sealing could be an issues..

i think if you get a 2mm alloy shhet, made an intermediate plate, ground some say.. 0.5mm deep and 2mm wide grooves on both sides, then get a sheet of something, say, 0.75mm silicon and cut out an oval strip (or even just use thin o-rings, but then you have to hold them in place with something), make the groove wide enough to accomodate the squash of the materials...

basically make our own "trojan" style gaskets....
i think they have the best chance of sealing

the next step is to go a metal-metal seal.. which is basically what o-ringing a head is meant to achieve...

metal to metal is always highest pressure resistant (but harder to form) and should take a few thousand PSI no probs...

BUT, Buta-N o-rings work fine with compressed gas bottles (except hydrogen) so a simple o-ring should be able to seal 30psi no probs(hence the trojan style gasket suggestion...

[30psi 4agte]

off subject slightly . I was playing around on the net and found these pics of formula atlantic setups.

Obviously trd realised that the design of the std 4a head had problems sealing around the ports! Hence they cast a new head with extra bolt holes in the middle of the port to help seal it!
Not to mention the different setup for clamping the r/c down.

So all i got to do to fix my prob is get a TRD formula atlantic head then change the flange plate of my plenum to suit ----- yeah right !!

Id love to just beable to pull one down and have a look inside to see if anything else has been cast different !!





BASTARDS !!

Makes my engine look like a dirty old stocker out of grandma's run down weekly bingo ride.

[takai]

I fail to see any extra bolt holes. Plus the fact that the Hasselgren engines are NA anyway, and we certainly dont have any issues with sucking that much air in.

Hasselgren actually machine a fair bit off the manifold mounting face on the FA engines, and im pretty sure that the nodule which you can see in the second picture is what is left of the injector boss. Because remember they use down throttle injection, and running to 11000rpm they want the intake runners quite short, with the butterfly on the second harmonic.

[30psi 4agte]

Hmmmmmm ---- i think/ know you are right !! I could have swore that was an extra bolt hole there.

[takai]

Yeah, it can look like it somewhat, there is a shim inbetween the two (not sure what its for yet) which sort of throws off the depth in the photo slightly.

[oldcorollas]

http://www.google.com/patents?vid=US...o-ring#PPA4,M1
http://www.google.com/patents?vid=US...1#PRA1-PA22,M1

and there are a few more patents...

i still vote o-ring doesn't need to be a big one.. you just need a mill, with a small bit to machine the groove (for say, a 1-1.5mm o-ring), and a steady hand/CNC to keep even distances away from the edges...
i vote for groove to be in manifold, or to have a 3-4mm intermeditate plate to house 2 orings.

edit: seems that under 100psi is condiered low pressure for o-rings, as the pressure is not high enough to have an effect ont he sealing ability, instead relying on the mechanical crush of the o-ring

[kingmick]

quote " Obviously trd realised that the design of the std 4a head had problems sealing around the ports!"


Its atmo so the air will take the path of least resistance and that would be the trumpet not a small break in the flange seal.The extra bolt holes would be there to support the manifold under the vibrations of an open wheeler etc if they where there, i think you will find!

[takai]

Its atmo so the air will take the path of least resistance and that would be the trumpet not a small break in the flange seal.The extra bolt holes would be there to support the manifold under the vibrations of an open wheeler etc if they where there, i think you will find!

Manifold is FAR lighter than the units ive seen in lots of open wheelers. I doubt they would have cracking issues, and in any case the entire throttle/manifold is a single thickish wall cast piece with CF hanging off the end, any cracking would probably be in the CF rather than in the injector boss.

I believe there is a small brace which runs about midway down the manifold between cyls 2 and 3.

[kingmick]

Its cast alloy and far heavier than carbon setup! its to do with fatigue of it, if it WAS used.
If you would like to see an open wheeler setup, give me a yell at one of the F3 rounds and ill show you over the car and ill show you whats inside the intake.

[oldcorollas]

so Mick, did Austrack have to do anything specail to seal the intake manifold for the mazda motor?
or you are not at liberty to/won't say?

[kingmick]

nothing at all, with a true deck and p00 it took 45psi without problem.