that mostly answered it

but if as you claim the Xcessive LIM proved not to make any more power than the factory LIM on a 700 hp engine, then why would you expect it to be any different by only increasing the primary intake port opening at the iron-intake manifold faces to the Cosmo size?

I’ve seen quite a variation on what a primary street port can be; from not much more of an opening into the rotor chamber than the factory unported size to being almost as large of an opening into the rotor chamber as the secondary port on the opposing front/rear iron plates. Which can be dependent on which casting is being used and the water jacket limits for it compared to other versions.
.

 

Were all aspects of the motor changed in the cosmo/FD comparison (intake ports, runner size, etc.) or did you just compare the UIM/LIM configurations? Aka, was the engine pulled apart and rebuilt as part of the comparison?

 

Ive tried it in more than one car.

I recently went from FD to cosmo Ports for both primary and secondary. No gains shown on dyno and no change in VE curve, that was on my own personal FD, I didn't intentionally do it but when I went from CAST to billet plates I got forced to do it.

I was hoping for some mystery gains but they never came ... That particular engine was bridge ported, I had higher hopes for it making a difference since the port was more aggressive on this engine vs my previous test which was only a street port.

 

Gotcha, I was mainly curious if the entire runner was adjusted, or if it was just either the UIM/LIM and/or port opening that is usually tweaked.

I'd assume the cosmo runners/ports give a notable boost to volume, at the expense of velocity.

 

there's a series of youtube videos that talk about the port shape/flow/timing, etc. They did silicone molds of the ports and apparently the 13BRE and 13BREW are internally the same but "cut" at a different angle which makes the port taller at the intake manifold side.

 

Yes the intake manifold was actually made for cosmo port. No point changing a port and not changing the rest. I thought that was a given.

 

Youll find at the port face FC is pretty much the same as well

Ive found FC, FD, JC all pretty much the same, The FC's seem to show a little more top end but I think that's more due to the FC intake. That was another interesting back to back. When we used to make an FC to FD adaptor plate for the upper intakes, we actually made less peak HP with the FD upper

 

all that data was from 1999; 25 years ago.

Not to mention they were all flowed for NA purposes rather than FI, and without manifolds. The one point that most people likely missed though, and it wasn’t in direct reference to Cosmo or not, but he did port for a turbo engine that was put up directly on a chassis dyno against another turbo engine that was also ported by somebody else. He stated they both made 500 hp, but the boost on his porting was only 15 psi and the other one was 25 psi. Which is where this off-topic part of the original discussion came about.

Which if you’re perceptive enough to hear it in his comments, he either completely missed the significance of that difference or pretended not to, which ever the case may be. Yet several times through out all those videos he states his main interest as NA development and little-no interest in forced induction development. The air flow requirement between the two is significantly different.

Yet over 30 years later people are still running a factory or near factory intake manifold that was designed for low-end response and only 270 bhp peak. Even as was stated over in the Turblown intake manifold thread, even that one is still pretty much just a rehash of the same ol’ … just as all the other ones out there are too. With them running all four ports open all the time too.

with one main exception; the 4-bbl manifold. Who knows though, maybe something different will pop up one day … 🤔
.

 

start at 6:10


and things often don’t stay the same over time as tech advances

as an example and pointed out on here starting several years ago, back in days past a T3 turbine housing today is not the same as in the past

starting at 12:36


piston engines making over 1000 whp on a T3 flange, which even now is represented by a smallish v-band having the same ID as a single 2” Sch 10 pipe opening (2.157”).
.