[Dave A.]

I took a look at the D-shaped intake runners on a later year 5MGE and noticed that the holes at the end of the runners where the injector nozzles sit protrude into the runner tubes. I'm thinking that perhaps this caused some problems with airflow turbulence and that the runner shape was changed from round to D-shape during 84 to help correct this problem. Any other ideas on this?

 

[Magnus]

I took a look at the D-shaped intake runners on a later year 5MGE and noticed that the holes at the end of the runners where the injector nozzles sit protrude into the runner tubes. I'm thinking that perhaps this caused some problems with airflow turbulence and that the runner shape was changed from round to D-shape during 84 to help correct this problem. Any other ideas on this?

Is this something simular to the d-porting that we did back in those days? I had a big v8 dported and it help the car run a whole lot better.

 

[Muchbzy]

I always thought it was a combo deal. It increased the HP and also was an emissions thing.

 

[Dave A.]

This was basically just a spur of the moment thought. The D-shape may have nothing to do with the injector placement whatsoever. I was just curious. Big V8? Would that be a SBC or BBC with a tunnel ram intake that has D-shaped runners? IIRC, I think some of the Weiand Team-G series or Edelbrock tunnel ram intakes were cast with D-shaped runners.

 

[Supra Bob]

Dave, Every Team G intake I have seen was a D shapped runner.... I had an older Edlebrock tunnel ram and it was round IIRC... but it was an older one so maybe they changed at some point

 

[jshober]

I port a lot of heads and we have a flow bench to test on and we always D-shape the exhaust port. It really smooths the flow curves out, it also helps with turbulence at high lift and high flow.

Joe Shober
D\R #10604
9.501 @ 147 MPH
ON RADIALS