Is This A High Port Sr20de

[FlossinPrimera]

I thought they quit putting low ports in in 93.5 model year. When driving my rev limiter is 8000RPM (I know I've bounced off of it before). I think I got screwed, I know that the engine I have is the original because this car has been in my family since new.

[JustinP10]

Do you have a JWT ecu, or other piggyback computer? If not your tach is VERY optimistic!

[FlossinPrimera]

Nope, all stock computer.

Ok here is a pic of a P11 G20 (which we all know to have the high port), it has the funky cover.

[T4 Primera]

Originally posted by FlossinPrimera
I thought they quit putting low ports in in 93.5 model year.

I think you've got that backwards - the high port engines are the earlier ones. Remember, plenum/throttle body on top = lo port vs plenum/throttle body underneath = high port. P11s are LO port engines.

[RYANS]

Does anyone make a cold air intake forthe high port manifold? If anyone makes a cai for it does it run to the manifold--any input will be appreciated.

[FlossinPrimera]

Ok. now I've gone crosseyed. . .

[T4 Primera]

Originally posted by FlossinPrimera
Ok. now I've gone crosseyed. . .

Ok, here's the good oil.

The earlier engines have the high ports (where the intake runners attach to the head), and the throttle body and plenum chamber (which is what you call the funky cover) is mounted underneath the intake manifold. That is, on the high port engines, the intake manifold runners curve UPWARDS from the throttle body/plenum, and into the cylinder head intake ports.

The later low port engines have the throttle body and plenum chamber mounted on top of the intake manifold (like in the P11 pic) so that the runners curve DOWNWARDS from the throttle body/plenum chamber and into the cylinder head intake ports.

IIRC, the reason they changed the position of the intake ports in the cylinder head was because, in the newer low port engine, they could avoid having so much of the intake valve guide protruding into the intake port. This was only of limited success because the low port position meant that the intake flow had to turn 90degrees to enter the cylinder. The older high port cylinder heads allowed the intake flow to approach the intake valve at a 45degree angle.

Clear as mud??

[P10DET]

Originally posted by FlossinPrimera
Ok, neither of those are my engine, but that is what I'm talking about, I have a 94 G20 (production date 1/94). It has a 7500RPM redline (indicative of high port, the low ports had a 7250RPM redline if I recall correctly)

OK, what would it take to convince you that's a low port?

[P10DET]

Originally posted by FlossinPrimera
I thought they quit putting low ports in in 93.5 model year.

No, they stopped putting high ports in the cars beginning in 94. IOW, 94 is the first year of the low port.

[P10DET]

Originally posted by FlossinPrimera
Nope, all stock computer.

Actually, you do have an optimistic tach.

Originally posted by FlossinPrimera
Ok here is a pic of a P11 G20 (which we all know to have the high port), it has the funky cover.

No, we all know the P11 has the low port engine.

[FlossinPrimera]

Ok fine its a low port, I always thought that the high ports were the newer engines. Oh well, change isn't easy.

[T4 Primera]

Originally posted by FlossinPrimera
Ok fine its a low port, I always thought that the high ports were the newer engines. Oh well, change isn't easy.

Hey, we're all here to learn right? It took me a little while to get my head around too.

[P10DET]

Originally posted by T4 Primera
IIRC, the reason they changed the position of the intake ports in the cylinder head was because, in the newer low port engine, they could avoid having so much of the intake valve guide protruding into the intake port.

Actually, it was for emissions reasons. The intake runners on the high port were often wet due to the placement of the runners and the injectors. They point more directly onto the runners, and thus wouldn't always get picked up by the intake air. The unatomized fuel results in poorer emissions.

I may not have explained that as well as I should have, but that's the essence.

[T4 Primera]

Originally posted by P10DET


Actually, it was for emissions reasons. The intake runners on the high port were often wet due to the placement of the runners and the injectors. They point more directly onto the runners, and thus wouldn't always get picked up by the intake air. The unatomized fuel results in poorer emissions.

I may not have explained that as well as I should have, but that's the essence.

No, you explained it well. Now I'm a learnin' somethin' too.

[P10DET]

Originally posted by T4 Primera
No, you explained it well. Now I'm a learnin' somethin' too.

Well, Mike Kojima explained it better. He explained exactly what this did to emissions. I'm not too good at emissions (except after a few Shiner Bocks :right: ). Hell, race cars don't have emissions crap, so why should I learn about it, right?