I don't expect the premise behind this to be received well, but please humor me. How much HP would be theoretically possible without BRAP? I'm starting a Frankenstein Turbo-NA built motor, and I'm going for maximum sleeper. It'll be a clean GT-style restomod vert with S5 housings/plates, S4 rotors, and Turbo II manifold. I want to port for a clean idle, no brap, but max HP from 14 PSI with meth. I want it to look and sound as classy and refined as possible at a stoplight, then unload a horde of angry bees behind me on acceleration.

 

Less overlap? Idk.... don't port it at all? The stock port will be fine with what it seems like you're going for.

 

I would say street port on the primaries. Clean up the secondaries and do not touch the Aux ports at all. This is pretty much what I did but I did open my secondaries a little sooner. I used Pineapple Racing Templates. Idles about 900rpm. It does surge a little sometimes but no brap. I also have no 6-port sleeves. Am still n/a at this time. HP not sure. I think I've read 300 to 350whp safely on n/a rotors. Not sure what boost achieved that. It was less than 14psi IIRC, but that was without meth injection if that's what you mean by meth.

 

Yeah, porting isn't necessary for decent power. I'm basically running that very setup--N/A block with stock ports and a quiet, steady idle. It's very unassuming until the wastegates open up. My exhaust makes it almost too quiet. It's 3" from the turbo with a Vibrant Ultra Quiet resonator, split to 2.5" duals with 14" oval Magnaflow mufflers.

People on here have reported making well over 400whp on stock ports. I'm going for 15psi on an S362SX-E, also with meth. I'm guessing that'll put me around or a little over 400whp on a Dynojet, but we'll see soon. I'll report back once the break-in is done and I get it on the rollers.

 

The 6 port irons already have about 1.5 times the port area of the 4 port irons, so if you want the cleanest idle, then leave the ports stock.

Remove the exhaust diffusers from the exhaust ports. And you can widen the exhaust port leaving the timings basically the same.

Why "14 PSI"? What about that boost pressure is special or required?

Keeping in mind that 14 PSI on a HT-18 and 14 PSI on a GT35R is the difference of about 200 HP.