leffes87rx7

I am rebuilding a series 5 engine and have street ported the front and rear iron using Racing Beats templates, as well as rotor housing exhaust. My old engine was ported at the primary ports as well
This was made by widening the bottom part c:a 5 mm to the outside of housing. I have now been told not to do that, but instead open up the top of the port c:a 10 mm.
My questions are: Why isn’t anyone offering a template for this? And should it be done?, and if so, how?
Please help, Thanks

diabolical1

iTrader: (3)

not fully sure what you're referring to with most of this, but there are templates available to port your primaries.

RotaryResurrection

iTrader: (8)

Yes, you should port the primary.

Best thing you can do is overlay the porting template for the secondaries onto the primary. You can use the same opening line for the primary. The closing edge requires more inspection to see how far you can go, since you are limited by the casting of the iron on that side. I would have to get out my own templates to compare the secondary and primary closing before I'd feel comfortable telling you how far you can go, but you should be able to extend the closing side of the port at least 3-4mm safely, perhaps more.

bumpstart

here is a few examples of G turbo middle plates to show you how late that primary opening edge is compared to a mild ported secondary ( with a stock opening edge )


( they different plates in the pic , ported the same on the same day but example more or less as a stock plate marked up ready to cut and an end result )
i think the US D plate may also be a little more conservative on the opening edge

..though i think the OP may be referring to the NA engine
..which if s4 has limitations on how tall you can port due to the vertical ACV passage
( methinks the s5 NA engine is horizontal passage and thus restricts the lower edge porting like in this turbo "G" middle plate example )

to the OP -

mark out the secondary port edges
( especially the opening edge line which is several mm outboard )
then use a set square ( not including RE and REW engines ) on the runner openings top and bottom to scribe across to dictate the possible top and bottom edges

this way the open edge will still support the side seal ends .. and port timing isnt open any early than the secondaries where before and thus engine vacuum is still very strong

leffes87rx7

I got it, Thanks a million. Now, the old engine with a big bridge ports on secondary’s and very minimal porting in the center (primary) was setup with 720 cc/min primary injectors and 1680 cc secondary’s. With this new street porting’s should this setup be modified? For your info. I will still use Himni Racing FC V2 TO4R (T67) Turbo Kit and got a Haltech E6K and aiming at 14-15 psi boost, and about 400 whp. I am a born gear head, but have no, nada, zip, zero experience with rotary, and I hate to repeat mistakes already solved by others. Please have patience with me. Someone said long ago that, “there are no stupid questions, only stupid answers” Hell I don’t know by now……

bumpstart

injector sizing already supports 400 rwhp easily so no change needed except to the tune as the volumetric efficiency will have shifted

leffes87rx7

Very well, I just learn how to calculate the balance between air volume and injector size needed for right mixture (good site by Howard Coleman) However, I still don’t grasp the balance between primary’s and secondary’s and what impact (if any) the size of porting difference have on that calculation, i.e. My old engine had a big secondary bridge port and std. primary port. The new one, same size street porting on both ports. My professional tuner probably known all this, but it will take me 3 more weeks before I am ready to tune, eager to learn…..Thank You much.