Can anyone here tell me what the stock diameters are for the intake and exhaust ports on the LSJ head? I understand the exhaust is more restrictive, and thus likely a smaller diameter. If anyone has these numbers available (mm or in.) I'd appreciate it.

More specifically: The port tract, not the immediate inlet which people usually "gasket match" I'm looking for the diameters that feed down from the inlet to the valves. thanks guys

 

thirsty thursday bump

 

It's not strictly a diameter measurement, port shape has a lot to do with it. I do have those valve seals also

 

Oh I see, I was going to use some flex hone just to smooth it out a bit, perhaps a bit more on the exhaust side, but they sell all different shapes and sizes so I wanted to get as close as possible to the port size.



I'll pass on the seals I just bought the rebuild kit from GMPD that comes with them...thanks though.

 

Ports go from two smaller runners around the valves to a larger open area, then taper back down towards the manifold. Gonna be hard to pick a specific size bit to do the whole thing in one pass. Gonna need some open-cut carbide burs, then some finishing bits. I forget what the one I used was called, but it leaves a fantastic finish on aluminum and works super quickly. I did my boy's head that way and it was by no means a fast job, but a lot quicker than sandpaper.

 

Thanks Joe, I ended up just picking up a DIY porting kit for like $16. looks like it has everything I should need:



Standard Abrasive 260001
Kits include:

* One 1 in. mandrel
* One 2 3/4 in. mandrel
* One 4 in. mandrel
* Two 1 in. x 1 in. 120-grit flap wheels
* Four Cross Buffs, two medium and two very fine grit
* Seven straight 1/4 in. diameter cartridge rolls--two 40-grit and five 80-grit
* Seven straight 3/8 in. diameter cartridge rolls--two 40-grit and five 80-grit
* Seven straight 3/4 in. diameter cartridge rolls--two 40-grit and five 80-grit
* Seven full tapered cartridge rolls--two 40-grit and five 80-grit
* Two tapered 60-grit rotary stones--one 11/16 in. diameter and 3/8 in. diameter

 

you should just send it to lsjion and get it done from the looks of things you dont have the knowlage to do it right and your kit dosent have enoungh stuff to do the job

 

I would send it to euthanasia, he has good prices and does a great job, roughly a 3-4 psi drop over stock head

 

There's no reason I'm not capable of doing this, so I will. It'll just be basic smoothing, gasket matching, bowl, and short side radii work mostly on the exhaust side. I won't be touching the valve seat areas and I'll save nearly $500. I'll have a machine shop deck the head surface. Hopefully I'll see the same psi when dropping from a 2.9 to a 2.8/7 (haven't decided). Thanks guys.

Also, what am I missing from the kit? A rotary wheel?

 

There is alot more to it then just smoothing and porting, if it was that easy everyone would be doing it instead of just a handful of people and machines, chances are you gonna put alot of time in it and see minimal gains, or the other side of the coin go ape **** on the head and overport it and go into a water jacket or just loss overall eff.

 

Well then how do the pros (manually) do it... trial, flow bench, and error?

 

Pm euthanasia, I don't port so I have no idea, I would guess trial and error at first then they get it flow benched and tweek it to get a final product, euthanasia works from a model but will flowbench the head he makes you for some extra money

 

I see, thanks man appreciate the help.

 

short turn radius isn't really the big deal LTR is however, if you lose too much of the str, you lose velocity and tq.

 

sure thing man, see one of the hand porters chimed in

 

I now port the heads with a CNC to get the big stuff out of the way then hand finish them. I also have molds of the ports I use for referance when hand porting. I guess you can say I stepped my game up a bit lol.

 

baller lol

I bet that saves time

 

Sure does