88 SE

Bought a blown turbo engine to pull apart for parts and was looking for some advice on whether or not I should use these ported irons. Don't mind the corrosive looking goo, the previous owner used some of that horrid coolant system sealer and it comes right off.

Anyway just looking for general comments on the port work the previous builder did. The engine looks to have been assembled by a complete idiot as evidenced by having 1 S4 and 1 S5 TII rotor housing (different plug hole locations) and I wanted to make sure the irons are ok to use. Center iron is a 100% stock port so this is front and back. Only thing I worry about is oil control rings and whether he ported into them or not.

RotaryResurrection

iTrader: (8)

Very nice finish work/execution. I do not like the shape of it much at all, though. You want the closing edge to be a fairly straight and defined edge, not a long curve like that. It looks to be about as early-open-timing as is possible without the side seal leading edge falling into the port, but it's hard to tell exactly what you've got without laying a port template or mapping jig over the iron.

bumpstart

agree
whoever it was didn't have a fine tip to add much shape it that top corner but looks to have done a reasonable job in the bowl and has found the extreme edge of retaining the side seal
but overall it looks Ok and especially there is no witness evidence of it picking up the leading edge of the side seal on the port top

the curved top V's straight top is a matter of opinion
many templates out there. not all of them are straight top
// considering the rotor closing edge and the path of its orbit are not a straight line
then i think having the top edge straight is only for aesthetic reason

also the sharpness of the shape in the top inboard of the port isnt especially critical
.. while it does increase port area.. the effective open "full lift " time here is very minimal compared to the rest of the port
having had to do one once to clean up someone elses porting ,, even to my surprise these lolly pop port shapes run fine and mild

if the rest of the plates prove as consistent then resuse

John Huijben

iTrader: (1)

Looks like it's been ported into the oil seal track to me, try placing an outer oil control ring on the iron and locate it using a caliper. Place a flashlight in the intake side of the port and check if you can see light between the port and the oil control ring

gxl90rx7

iTrader: (1)

side seal eater

RotaryResurrection

iTrader: (8)

IF it were a side seal eater he'd have known about it already and wouldn't have even had to ask us.

RotaryEvolution

iTrader: (30)

i'd be more concerned about oil consumption since the port is inside the oil seal track line. did the previous engine burn oil?

88 SE

No idea to be honest . That's what I couldn't tell it looks like he brought the port right to the oil seal line

RotaryEvolution

iTrader: (30)

were the rotors oily on the combustion surfaces along with exhaust ports oily and carboned up?

oil consuming engines usually do not have much hard carbon deposits inside the engine aside from the exhaust ports.

it's always hard to tell when someone doesn't give you the full story.

if the inner oil seal carriers are doing their job correctly the engine probably will be fine. however the outer oil seal carriers generally do all the work on engines with tired iron end plates. if the shiney surface of the outer oil seal carries over the line into the intake it will eventually burn oil(if it isn't already). the track line in the port already indicates it is crossing into the sealing surface of the outer carrier.

whenever porting i never touch up the opening where the oil seal rides. leave it unmolested, even if you aren't gaining that .5% flow increase. function over form in porting, but smooth and larger is still the aim.

88 SE

It didn't seem any more oily than other I've torn apart. I had no history on it at all just bought it as a core. I'm not really on a tight budget so if there's a chance it'll smoke I'll just grab some others .

RotaryResurrection

iTrader: (8)

I always take that rough casting lip off just enough to polish it clean while leaving the line basically the same, or maybe removing 0.5mm of material from it. That doesn't change anything in terms of oil ring sealing but it makes it look nicer and may help flow slightly.

RotaryResurrection

iTrader: (8)

When I mapped my port I built a jig that let me assemble irons, a shaft, and a cutaway rotor with exposed side/corner seal slots, but no rotor housings. This way I can move the rotor and trace all the seal paths I want, and even experiment with "feeling" how a side seal acts as it crosses the closing line of an intake port. I can test how different port shapes work this way. I found that the outermost corner of the port where the tip of the side seal crosses is very important, and the straighter you can make that closing line with a small/fine curvature, the better it is for the side seal, and having the shape off by a couple of mm can make a big difference.

I also examined the stock port opening and closing sides and specifically the angle of the closing side in relation to the rotor/side seal. Then when I decided to extend my custom port I put that exact same angle back into the design at the revised closing timing line (thus my raised straight line) so that I would have exactly the same closing action on the side seal that the stock port used to prevent seal wear.

It seems that although a port design with lesser closing scissor action might still work, it would almost certainly increase seal wear and iron wear, so I don't see a reason not to do it that way.

diabolical1

iTrader: (3)

i basically do the same thing. i'm not even sure if i take 0.5mm off it because there are times when i can still see some of the casting imperfections when "done". at times my perfectionist ways/OCD (or whatever) tempt me to try to get them as "pretty" and uniform as some of the ones i've seen in photos here, but my fear of touching the oil line keeps me from it.

RotaryEvolution

iTrader: (30)

for the most part that is what i'm referring to, everything else gets a real amount of material removed versus the inner edge. looking at some port jobs you can see that some people spent way too much time and removed too much material from that inside area and cut into where the oil seal rides.

i don't see yours going into the oil seal track but the OP's does, as i have seen numerous times. new oil seal carriers have less contact in this area and also more prone to leak.

even taking the used outer carriers and measuring the wear pattern i bet it is over the limit of the amount the OPs was ported across the line, relying heavily on the inner carrier to keep all the oil inside the rotor. his second photo gives an idea of how much material was removed, cutting wide and rounding off the port more than leaving it orange sliced(or whatever you want to call it).

88 SE

I'm gonna do the marker test... Paint the port and see if the oil ring scrapes it off or not

88 SE

Looks like all is well, put a rotor on the iron and plugged in the e shaft to check out all the port clearances. It's an extended port that seems to be done well. The inner edge of the outer control ring does not become fully exposed as it passes by the port so it should have no problems.

That said the ports are fairly aggressive and are in fact an early open port. Probably too aggressive for my taste as I want a smooth 800rpm idle so ill be putting the set up for sale since all the parts are super clean aside from the rotor housing that are a seal.

If I had to guess I'd say it has no more than a few thousand since the rotors barely have any carbon on them and the step wear is very very low.

Thanks everyone for all the input. I'm a few steps closer to just going 1jz since finding good internals is becoming a real PITA!