Photos of my home port job

[Xnke]

Ok, this is my N42 head, during the assembly phase. Photos are the best I could do with my crappy camera. I think i have some more, but i'd have to hunt them up.

 

Photos of the ports:

And then a (blurry, arghhh) photo of the chamber side:

 

 

So, Now that you've seen the ports, it's time for the specs:

 

Combustion chamber CC's : 42cc's, within .25cc of each other, and 88MM cylinder diameter

Port size: 38mm intake, exhausts are 2mm taller and 4mm wider, to match the gasket and my header better

Intake flow: 171cfm at .454" valve lift, pretty dang good, I think!

Exhaust flow: 119cfm at .454" valve lift

Intake valve is 44.5mm diameter, swirl polished

Exhaust valve is 38mm diameter

Both intake and exhaust seats have been opened up to fit the port and valve, as seen (kinda) in the crappy photos above

 

Cam is a 234* duration at 0.050" lift, .454" max lift cam from delta. Springs are Rebello outers, and stock inners; supposed to be good to any lift I'd ever be running on the street.

 

Anyone care to comment? I meant to post this before actually assembling the engine and running it, lest i needed to make changes/improvements.

 

As soon as I get the dang thing roadworthy and halfway tuned up, I'll head to the dyno to get a set of curves, and we'll see just how good or bad I really did.

[Tony D]

I know people who run 0.575" lifts on the street, will those springs work?

 

The opening part of the runner to the valve bowl seems 'necked down' more than usual. Hard to tell by the photos whether you are imparting a spin into the bowl, or just haven't opened them up equally on each side.

 

What does the manifold port flow for the one you are using (have you checked flow with the manifold on the head, in other words, to see if you overdid your ports or have to work the manifold?)

 

Knowing what the manifold does to the head flow numbers lets you make decisions on altering the runner tracts to get something flowing better or more equally.

[Xnke]

According to Rebello, the springs are usable to .600 lift or so, and can hold off valve float to 8000 RPM. They are the "A" spring set, that they sell. for 120$, I think they're just peachy, myself.

 

As to the visible offset in the ports: Yes, I noticed that when I was doing the porting, and decided to use it, just to see what happened. It's not nearly as severe as the photos make it out to be; it really looks scary in the pictures. Seems it did ok, although after looking at some BC Gerolomy porting sheets...I think the flow bench was optimistic. I really don't see my port job flowing on par with at BC Gerolomy job.

 

The manifold hasn't been flow tested; at the time I sent the head to to machine shop to have the valve job done, they put it on the flow bench as practice. They had just bought it and were still learning how to integrate the measurements into the graphing programs the machine came with.

 

Basically, the manifold that is on the car currently is tapered up from 38mm up, as the E46 manifold tapers up internally. All I did in the manifold was match it to the ports, and smooth the internal finish out wit sanding wraps.

[Daeron]

88mm bore and a fairly small-chambered head.... but an e-46 intake manifold? 3 liter with SU's?

 

Did they measure all the ports individually to give you comparisons from cylinder to cylinder?

[Xnke]

Yes, the lowest flowing intake was 170, the highest flowing was 172, and the exhausts were all within 1CFM, except #6, which was 117. I touched up #6 a bit when I got it back, hopefully it picked up some.

 

Yep, 2883cc's, 9.5:1 compression, and it runs on 89 just fine, so far. Su's for now, conversion to fuel injection is in the works for later.

 

L28 crank, L24 rods, Z22S +1mm pistons, N42 head.