Thanks Dave. Now that you mention it, I do have an S4 NA set with 2mm apex seals. What if I used it? I like your reasoning. As for torque and HP numbers, did you mean 145-150 foot pounds and 185HP?
Sounds a bit more reasonable. That would be great in the truck with the driveability of the SC and response of the S4 set.
My apex seals are also standard Atkins 2 piece 2mm ones.
My flywheel choices are Racing Beat light steel and stock S4 NA (N326). I have the proper S4 rear counterweight so I can use either flywheel.
Do you think I should use the stock flywheel (I think it's 24 pounds) since it's a truck? Or will it slow down the response of the SC a lot? I only ask this because I'm used to driving this S4 engine with an aluminum flywheel with SC and in NA mode in my 1st gen and it's a little light in the bottom end when NA but still very driveable thanks to the low weight of the car.
Back when I tried the 5" and the 7" on this engine in the 1st gen, the superchargers caused the rotating assembly to feel a whole lot heavier than it really is. I actually started originally with a light steel flywheel but switched to aluminum precisely because the light steel felt heavier than I wanted.
I realize with a truck's added weight there will be compromises, but that's all I want it to be; a compromise. I don't want to return to the days of driving around something that feels like a 30 pound flywheel, which I'm affraid might happen if I use the 24 pound stock flywheel (this happened in my brother's RX-4 with GSL-SE assembly, GSL-SE flywheel and my 5" SC. With SC it felt like it had the old stock 30 pound flywheel, but in NA mode it felt lighter and much better). The 30 pounder is too extreme for daily driving, and only basically useful when hauling a large load or towing. Aluminum would probably be fairly useless for the same (opposite) reasons, even if adding an SC would help by adding rotational mass and all that, possibly making it feel more like a light steel in NA mode.
Instead I want a compromise that will drive like it has a light steel flywheel
with an SC, or a 26/27 pound GSL-SE while NA. But then again since it is a truck, I'm willing to bend a little and accept the 24 pound FC flywheel with an SC, but I'd like some feedback as to how it drives.
84stock has an S4 engine with a 7" SC and stock 24 pound flywheel in his 1st gen, and he actually endorses it because it gives him a better launch.
I think I'll leave it at that and move on to the pressure plate and clutch disc. I have a Racing Beat street strip pressure plate in 225mm and two choices for clutch discs. 225mm HD and stock '83-'92 Exedy/Daikin. I like the thought of using the SS p-plate in the truck because it's similar in grip rate to the stock REPU type. I also have a stock aftermarket Daikin pressure plate in great shape if I want to use it.
As for the discs, I like how the OEM REPU disc has some buffer zone with center springs and marcels, like the Exedy disc. The HD disc lacks marcels so I'm a little paranoid about using it.
Like you said, if I'm racing I should go with 3mm apex seals. Well, I'm not racing, so maybe I can get away with the Exedy disc and save the HD disc for another project I have in mind (which will actually need it).