I built my own S4 NA motor last year with my own street port and it made a great power band. The car ran a 14.7@96 at the dragstrip on a 89 degree day, so it was definately a good FC NA from a performance standpoint. However, after 7k miles, a side seal died and I recently replaced them and checked out where the seals were hitting my ports. The areas where my closing edges met the opening edges of my ports were where the seals were hitting, so I filed a bevel into them. However, one day after putting the motor back together, another seal got eaten!

I didn't scissor my closing edge of my large aux port, and its closing edge is very wide.

Anyone have any hints about side seal protection on large street ports? I know u don't want to give out ur porting secrets, so I'll understand if u just give me a hint.

Thanx in advance, engine builders.

 

Ok.
The most important part when porting an engine is to:Allways rotate the engine while it is still open on the bench with the eccentric shaft,and rotor in place.
Carefully examine the line that the corner seal makes,and mark it clearly when your next step will be porting.

I have attached a pic.You will see that the porting style is far from a streetport,but you can clearly see how the corner doesnt interfere with the port.
He left ample space for it to move,even if it moves a bit in the rotor,it would still be ok.There is 2mm extra meat before it gets close to the port edge.

The 2nd pic shows it a bit more clearly(it is obvious that the engine has been over revved).

Try to leave at least 2mm at all times,but more will ensure that it lasts longer.

Do you perhaps have a pic about your ports?

Karis

 

This is covered heavily in the "other" forum.


-Ted

 

Thanks for the tips, and yes I looked over Ito's thread on nopistons, but there are other secrets that are involved, lynn e hanover covered the scissoring tip and I'm looking for some food for thought as to how else I could protect my side seals. Ted, u don't show big pics of ur ports probably for just this reason, there are very important but small details involved. Ha ha, I understand if ur secrets are to be kept that way.

I'll definately lay out some concrete boundaries for my ports this next time I build a motor, using the corner seal and side seal openings. I've been told to use a plexiglass plate over the rotor, with my porting template traced on it to see how my old ports interacted with the seals.

 

That sounds like a very good plan to make sure that your port edges dont get in the way.
I havent thought of that one,i normally used die,to see where it traces lines

Karis

 

Yeah, I don't leave large pics of my intake ports for that reason.

I would think Judge Ito's pics are large enough to see the details?
http://www.nopistons.com/forums/inde...howtopic=33859
I think it's pretty straight-forward?

As for the closing profile, I think Lynn E. Hanover mentioned using a plexiglass template and flipping it over on a rotor + rotor housing and spin the e-shaft to check the closing angles on the port.
This is one of the reasons I make my port templates out of plexi myself.

If you got any questions, I can try and answer them...


-Ted

 

This should be a great start, thanks for the help. I know for sure that my aux ports do not scissor with the rotor on the closing edge, and that may have been the problem.