Large port exhaust gaskets??

[Meatball]

Im in the process of a bit of port matching and came across a bit of difference between the exhaust ports and the manifold ports



Black lines are manifold ports.

Ive tried making the ACT one i was using bigger but its fallen to bits in the process any ideas where to find a bigger one?

[Boosted LS1]

Rob at V8D should have some bridged items. They're quite good imo.

[Meatball]

Boosted LS1 said:

Rob at V8D should have some bridged items. They're quite good imo.

Cheers Boosted

[Meatball]

Im not having any joy finding any gaskets to fit the exhaust ports on my heads. Both J Eales and V8D said they dont do them that big which is a little worrying. It looks like im going to have to try the high temp silicone route.
Has anyone tried this?

[Hoover.]

I might be missing something here...... but what difference does it make as the manifolds will still be restricting the outlet

[Meatball]

Hoover. said:

I might be missing something here...... but what difference does it make as the manifolds will still be restricting the outlet

Hi Hoover, The manifolds are in the process of being opened to match the heads

[Hoover.]

Meatball said:

Hoover. said:

I might be missing something here...... but what difference does it make as the manifolds will still be restricting the outlet

Hi Hoover, The manifolds are in the process of being opened to match the heads

Arggh makes it crstal clear now....

How are you opening up the manifolds out of interest ????? or are they new ones ???

[Chimjunkie]

Ben, that's a bit more extreme than mine were!! I had to Dremel 1-2mm off along one edge on all ports. I have not used the metal exhaust gaskets this time so trimming these were easy. There was plenty of metal on the solid steel exhaust flange to taper down and match the head.


Thanks Spend for the suggestion to have a look at this little tweek!

[Meatball]

Hoover. said:

Meatball said:

Hoover. said:

I might be missing something here...... but what difference does it make as the manifolds will still be restricting the outlet

Hi Hoover, The manifolds are in the process of being opened to match the heads

Arggh makes it crstal clear now....

How are you opening up the manifolds out of interest ????? or are they new ones ???

Im using a drill and LOTS of dremel attachments its not too bad once you get going, Im using the existing manifolds. i just hope i can get them to seal

[Chimjunkie]

Meatball said:

Im using a drill and LOTS of dremel attachments its not too bad once you get going, Im using the existing manifolds. i just hope i can get them to seal

Theoretically, the head ports are not changing therefore the contact area on the gasket will not change as long as you dont overdo the porting on the exhaust manifold? Shirly!?

[Meatball]

Jon did you measure the size of your ports by any chance? mine look bloody huge and im not too sure thats a good thing. They measured 40mm x 30mm which is approx 10% bigger than any gaskets i can find.

[HarryW]

Chris on a bike how big are you going, if JE, V8D or ACT don't do them big enough . What else are you doing to the engine, I can only assume using a blower as if it stays NA you mght not have any port velocity for it to work properly sub 3Krpm

[Chimjunkie]

Meatball said:

Jon did you measure the size of your ports by any chance? mine look bloody huge and im not too sure thats a good thing. They measured 40mm x 30mm which is approx 10% bigger than any gaskets i can find.

Will post a picture of the gaskets I got from Rob. Give me 5 mins. No didnt measure me ports..

[Chimjunkie]

Right here we go.



The graph paper has 5mm squares. Should be plenty of material on this?

[Chimjunkie]

HarryW said:

Chris on a bike how big are you going, if JE, V8D or ACT don't do them big enough . What else are you doing to the engine, I can only assume using a blower as if it stays NA you mght not have any port velocity for it to work properly sub 3Krpm

What we are talking about is only matching the exhaust up to the existing porting of the head. Not further opening up the head!

[Meatball]

Chimjunkie said:

HarryW said:

Chris on a bike how big are you going, if JE, V8D or ACT don't do them big enough . What else are you doing to the engine, I can only assume using a blower as if it stays NA you mght not have any port velocity for it to work properly sub 3Krpm

What we are talking about is only matching the exhaust up to the existing porting of the head. Not further opening up the head!

The heads were big valve as standard and the ports were opened up last year by Jamie at CRE so im 100% sure he knows what hes doing. (if your reading this jamie you do know what your doing dont you ). Harry Port velocitys well over my head but theres no denying the car makes good power at 298bhp for a 450 (even with partial blocked exhaust ports). I`ll try and post a piccy tommorow of the ports to show you.

Thanks for the piccy jon those gaskets look around the same size of the act ones i had on which are the biggest i can find.

[spend]

Port velocity will be more affected by the flange masking the port and/or primary pipe IMHO. Blending the port to the pipe through head & flange can't hinder flow, compared to the standard steps & rebates? Surely keeping the momentum is the desirable trait - rather than isolated spots of high velocity? If you constrict (by size or complex shape changes) to create high velocity its just going to make heat (a loss of kinetic energy?)

[Meatball]

spend said:

Port velocity will be more affected by the flange masking the port and/or primary pipe IMHO. Blending the port to the pipe through head & flange can't hinder flow, compared to the standard steps & rebates? Surely keeping the momentum is the desirable trait - rather than isolated spots of high velocity? If you constrict (by size or complex shape changes) to create high velocity its just going to make heat (a loss of kinetic energy?)

This was my understanding/hope. The gaskets i have been using the past year would have caused quite a disturbance in the exhaust gasses.
Im going to stick the car back on the same RR when im finished to see what difference it makes. If theres a loss in power i can always go back to the old restrictive gasket arrangement .

[2Munkys]

Have you considered making some gaskets out of anealed sheet copper?

[rev-erend]

2Munkys said:

Have you considered making some gaskets out of anealed sheet copper?

I spotted some of these of a race car down at the Brighton Speed trial.

Chatted to the guy and he got them custom made from some copper gasket company or other..

Just send them a pattern.

Thinking of doing the same myself.

Copper was about 1mm from the look of it.