Hey all. I currently run a 220whp NA B20vtec
In a 99 SI. Currently tranny wise I have been setup with my stock S4C gearbox with a Clutchmasters stage 2, Stock flywheel, running the factory optional VLSD diff. I was recently contemplating selling my box and getting a CTR spec box with the dual synchro helical diff but was wondering if it was really worth it to fork out the loot or if I would be better off just spending $$ on a quality diff such as a Qualife unit for my current trans. Also have had my eye on a lightweight flywheel from Fidanza but was debating whether or not it would be a worthwhile upgrade now or if it would be smarter just to wait until the next time I tear it apart to replace the clutch and change up then. Any input from those more experienced will be appreciated as I am much more well versed in engine related matters than I am with things further down the driveline.

 

I can't speak much about the LSD portion much as I have only ever run the gear type. From what I know, the gear type is stronger and will take abuse much better. For your build would it be worth the money? Probably not. Either type will serve its purpose and work fine.

Now on to the transmission as a whole.. NO I don't think it would be worth the cash. What exactly are you looking to gain? The main difference in the SI s4c and the CTR s4c is the diff and FD. Put a 4.7fd in your current tranny and basically you have a "poormans" CTR tranny. I actually will be running that setup in my B20 build. S4C gearbox but with an ITR LSD and 4.7fd.

I will also be running the Fidanza flywheel so if you can hang tight a few weeks I can give you my thoughts on it. I have driven on stock, an act street light and now a Fidanza. I should be able to give pros and cons. I can tell you running a lightened flywheel is a nice upgrade, but I wouldn't do it w/o balancing it to the motor and PP...that's me though, I tend to be OCD.

 

First off, you pretty much hit the nail on the head as far as the flywheel goes. In itself it isn't a very expensive component to speak of, but since I do have a few grand tied up in the engine and know how harmonics and such can effect the longevity of a high rpm build, I would most definitely want to keep everything in check and balanced. I don't want to just toss the lighter flywheel on my setup and call it done, which is basically why I haven't gone that route yet, so thanks for reinforcing that lol. With respect to the gearbox upgrade, mostly I am looking for a little more traction out of the hole and when powering out of corners in twisties. I also like the idea of the CTR FD gearset as well, however ideally I would like to go with a GSR 5th to keep highway revs down a bit as I do cruise multiple hours to the beach and other places throughout the season when I use the car. Please do let me know your feelings on the flywheel when you
Get it in and settled. This would be something I do over the course of the entire winter and probably would save that for last as my first goals are to get a more suitable 2.0 header and upgrade from 2.5 to 3" exhaust as I think the basic Header and 2.5 car back I'm currently running are not allowing the engine to exhale as freely as it should.

 

Also I just checked out your build page.....looks very healthy. If you don't mind me picking your brain once more, what type of gains did you see going from stock to the Edelbrock intake with S2 TB? Would you say it Is a worthwhile way to go on an NA setup over a ported ITR manifold/64mm TB? I always kind of assumed, based solely on the fact that stock pieces flow fairly decent themselves, that gains on a modest NA setup would be minimal going that route and kind of chocked that up to the list of things to do when I plan to add boost. That's soley because I'm at a "most bang for my buck" type of position right now. Thanks again in advance for your wisdom. Joe

 

My motor is not done yet. I should have it put together in the next month I am hoping. Just depends how long it takes to get some parts.

Now that you mention adding boost it changes the scenario all together. I personally wouldn't make the tranny any shorter by adding a 4.7FD. Adding a gear type LSD would benefit you in that situation. To be 100% honest, if you are set on boost I would sek out a GSR trannny w/ a factory LSD, or w/o and add one. Selling your current tranny should fund that adventure.

IF you decide to stay NA, a 4.7FD will be a nice "bang for the buck" upgrade.

You never mentioned what your motor build consists of to be @ 220whp. What cams/compression and all that? IDK if boost would be the best idea on a 220whp NA B20 because more than likely the compression ratio has been raised.

 

Currently I'm running a B20b block with 84mm 12.1 CP Pistons, Manley rods, stock crank, B16a2 head with Supertech VT, mild port work, Skunk2 tuner cams, S2 cam gears, Ported ITR intake mani, RC 330s, AEM fuel rail & regulator, AEM V2 intake, DC 4-2-1, 2.5" Thermal RD cat back, Tuned on S300. If I end up going the boosted route it wouldn't be for quite some time, probably another year or so and if that were to be the direction my quest for power leads me, I would definitely open her up and swap to a set of slugs that would bring my CR down around 8.5-9.5:1. More than likely though I will just continue to build a more and more powerful NA setup and possibly throw in a shot of giggle gas to get my power fix should the need arise. At this point though, this winter is definitely going to bring to the table a better header (thinking RMF or SMSP), 3" exhaust, and either the aforementioned transmission upgrades or new
Cams and an aftermarket intake manifold. (Budget will not allow me to do it ALL before next season) I've been happy with their products and camshafts in particular in the past, so Im leaning towards the Skunk2 Pro2's and Skunk intake manifold. My tuner has assured me that he could keep my cars street manners In check even with a larger/more aggressive cam profile that the Pro2s if I choose to go even bigger, but I'm not sure how wild I wanna get because I do street the car pretty much every day in the spring,summer and a good bit in the fall as well. The only time the car doesn't see near daily street use is in the winter months which I've traditionaly used as my tear down/rebuild time of year.