Block options, pleez

[Minh]

I am at the hump of the my U20 rebuild.

Background Info:
I have an almost new head. 100% stock right now - cam, springs, rockers, and SU carbs. New oil and water pump with electric fuel pump.

I am about to send the block to the shop for hot batching, honing (maybe), new freez plugs, and new side-shaft bearings. All this for $80 to $120 from a reputable hot rod shop in South Sacramento.

QUESTION:
Okay, should or should not I bore to .030?

THE INEVITABLE:
I will eventully swap out the tranny and motor for some kind of V8 or VQ33 turbo in about 2-3 years. But that is another story.

CIRCUMSTANCES:
If I did bore, will I need new pistons? Or can just used oversized Total Seal gapless rings? I getting gapless rings regardless.

Will I see any performance difference if I did bore it using the stock cam.

If very little performace gain, what am I looking at here to upgrade the head to utilize the new bored capacity. (Exclude the carbs and intake... this is no longer a fiscal option for me anymore since the swap will occur in 3 years.) This way I can cost out the upgrade.

Thanks!!
Your cagie wiley wisdom and experience is much appreciated.

[spl310]

If you are going to replace it in the future, don't do anything extra that you don't need to. If you bore it, you WILL have to put in new pistons. You cannot just put in bigger rings as the pistons will flop around in the cylinders and the engine will fail in short order.

[oilleak]

In my opinion, if your really going to do an engine swap, do it now. You're wasting money rebuilding a U20 that you're not going to keep. The reason I say that is that a propper rebuild on one can't be done for less than $3K. It's a grand for the timing components alone now. Here is a link to the costs page on my site http://web.tampabay.rr.com/oilleak/Costs.htm
These prices are long gone and I did everything except the machine work myself. An impropper rebuild of a U20 will end up costing more.
If you go ahead with the rebuild, I would bore it out an put new pistons in. I have never once had good results re-ringing an engine - roadster or otherwise. It'll run if you just re-ring it but you'll likely wind up with less than perfect compression and oil sealing. If you only re-ring it, you need to use a cast iron ring like a Deves - the chrome ones like the OE Nissan rings just won't seat in old bores. I've never used the total seal rings and I woudn't spend the extra money for them unless I ws doing a proper rebuild, which means new pistons.
Next, why 030 over? If that's the machinists recomendation, go with it but as a rule (unless were going for all out performance - think at least $6K for a U20) you should bore as little over stock as needed. you can always re-sleave a block that's been bored too far but that adds cost down the road.
As for the head, no need to do anything beyond a valve job and making sure the guides are good. A completely stock head flows enough air to be competitve in regional SCCA EP races - It's a great head. I know of one completely stock (CSP legal) engine that dyno'd at 131 HP at the rear wheels. That's an honest 150 at the flywheel. I haven't dyno'd mine yet but will soon. That engine had only solex's, B cam, and a port matched manifold - not even any polishing of the ports. If the heads been cut more than .020, shim the cam towers.
If you're looking for performance, the best money you can spend (which is quite a bit) on a U20 is solex's and a B cam. I'm kicking myself in the butt for waiting so long to put mine on the car. Huge differance over the stock cam and carbs. It's damned impressive too. I've had several people comment on how the car sounds at full throttle. One guy how was standing near the finish line at an autocross said that when I came by (WOT at 7K rpm) you could literally feel the air being sucked out of the atmoshear! Bill Harvey told me that he had a problem with the SCCA 98dB rule not because of his exhaust but because of the roar of the solex's (the meter read 102dBa!).
If I had it to do over again, I'd seriously consider an SR20 swap as the cost for a take out engine would be about the same, but it would put me in an SCCA class the I don't want to run in though. All in all, I've never been happier with my car than I am now with the solex U20.

[oilleak]

One more thing. If you decide to build a keeper out of your U20 - spend the money to properly ballance it! If you're going to just freshen the motor and replace it (be sure now) in a year or two, don't bother as nissan's machine work was first rate and everything should be pretty close to in balance already. If you're going to keep the engine for a while and especially if you're going to run it at high revs, ballance it. The entire rotating assembely (crank pulley, flywheel, and pressure plate too) and also the rods and pistons. Do the whole thing. There was a thread on engine ballancing on the mailing list a year or more ago. Search in the list archives. It give good advise about finding a shop that knows how to ballance. Tells what questions to ask and what type of ballance machines are best - I don't remember which was but the point was to find a shop that has good equipment AND someone who knows how to use it. It doesn't have to be the same shop that does either the block or head work.

[Minh]

Thanks a lot oilleak!!!

Oh, I forgot to mention that the the timing chain and related parts are also all new. It came with the car.

I looked and discovered I need new clutch discs and pressure plates.

At this point cost wise I am looking at a full $500 for a fully rebuilt motor. And from the info you all mentioned stock is the way to go. Hell, I might as well get the stock turquoise blue paint too!!

Although a Roadster purists in me wants the B-cam, solex carbs and intake, and other goodies.

The pragmatists in me wants the affordable route to a reliable running U20 and tranny worthy of resale later. The only needing the remaining comp pieces from the next owner.

The tinkering speed demon in me wants more power and bragging bolts to boot...

So, I am out voted 2 to 1.

However, I left a window for reconsideration after driving the newly fresh motor and tranny and go U20 comp if I the other 2 sides of me can live with the full comp U20...

But geez does that VG30 EFI turbo looks kick'ass underneath the hood.

[oilleak]

One thing working in your favor is that it's not hard to bolt a B cam and solex's onto a stock engine at a later point.
Good luck!

[SLOroadster]

With the set up I have, my car flies. It still needs a little tuning, but it will get on it when provoked. The lightweight flywheel is rad. I will have a few lightened steel flywheels for sale soon. I'm looking for a target weight of about 15 lbs. They should be resonably priced but I won't know until the first batch are done. The B cam and SUs works pretty well also. I had that set up last spring. You won't be disappointed with the solex set up, especially if you run a slightly larger exhaust (I have a 2 inch inner dia.)
just my $.02

Will

[oilleak]

That's a good target weight for a lightend steel flywheel. Mine is 15.5 lbs with most of the weight shaved from around the perimeter. I haven't run the aluminum FW yet. Too bad those are so hard to come by.

[Minh]

With the set up I have, my car flies. It still needs a little tuning, but it will get on it when provoked. The lightweight flywheel is rad. I will have a few lightened steel flywheels for sale soon. I'm looking for a target weight of about 15 lbs. They should be resonably priced but I won't know until the first batch are done. The B cam and SUs works pretty well also. I had that set up last spring. You won't be disappointed with the solex set up, especially if you run a slightly larger exhaust (I have a 2 inch inner dia.)
just my $.02

Will

Will...

The 15 lbs flywheel a real improvement on a street rod. The lighter flywheels in general create more RP, and wouldn't it cause more wear and tear. I don't understand...

I hope you have them ready... after the motor and tranny are back in I am more hesitant to pull it back out.

[SLOroadster]

The light flywheel shouldn't cause any more wear. It just doesn't weigh as much. If anything, it might cause less wear due to less mass that needs to be accelerated. I am having a bunch made. My machiniest is working on the first one right now. I will also have some short shift levers, I have the first one of the bunch on my car now. The throw is about 4 inches. The rest need to be rechromed. I am working on a buch of other stuff such as reproduction solex throttle linkages as well. Psudo-aftermarket parts for roadsters are cool. If you have any ideas let me know.
Will

[Minh]

How's about an LSD upgrade?

[oilleak]

That's a whole new can of worms. I'll probabley post some info on that tommorrow as I have to set mine up and the whole issue is very confusing as there are multiple different diffs, cases, and other parts. Nismo is on my list of folks to call tomorrow. For what it's worth the Limited slips are hard to find and pricey. They can be had though.

[SLOroadster]

Sorry folks, but there are no more H190 LSDs. You might still have a shot at finding one in Japan, but here in the states they are NLA. I happen to know who has the last one NISMO sold, and no the owner is not going to sell it. It resides on a 67.5 2000 however. I got lucky when I found mine, it is mounted and ready to attach to the car, 4.11:1 all new pinions and ring gears ect. Can't wait to try it.
Will

[oilleak]

They're out there. just don't expect to find one this week. I got mine off of ebay for $101 including shipping! You're not likely to duplicate that score - mine was the only one I've seen on ebay. I know where another one is - used $800 - if it's still available, and another guy I know just got one too. It is probabley the rarest of all the hot roadster speed parts though. If you want one quickly and it's not illegal in any racing class you run, you can swap axles. Mark Sedlack just updated his site with pics of his Ford axle swap. Not cheap but then neither is a Nissan LSD.

[SLOroadster]

I paid $1000 for my LSD. That hurt. But it is NOS with the rest of the rear end as well