To inspect or not? RB20 bottom end

[RustspecS13]

So my RB20 is apart and its going back together soon.

Right now its apart because it bent some valves and the head is all finished. I got used valves from a forum member and had all the seats on the valves and head cut so they will all seal perfectly.

And so far the RB is all stock, minus the holset HX30. Soon it'll have nistune and 450cc injectors.

The goal is 7500rpm and 250-300whp (really just wanting good power band and decent hp) for now. Later I want to be turning 8500rpm with an upgraded oil pump and all that fun stuff.

The problem is I have no idea how big my oil pump drive is and how big the drive for it is on the crank. I don't want to run into issues with it because I want to drift it all season with out going into the internals. I have an oil pump gasket, so should I take it off and see how its is? It only has 3K on it since I bought it and it has a new regular (non n1) oil pump.

I also would like to pull off a few bearing caps off the crank and rods to inspect every thing but I don't want to mess with a good thing you know? If I do, there's a risk of over streching the factory bolts or them failing down the road. And if I get new arp rod bolts i might as well get rods, and forged pistons etc etc, and it snow balls from there.

So here are the options:

1) leave it alone, put the rebuilt top end on and drive the wheels off2) check the oil pump drive and maybe get a collar that just screws on 3) pull apart the bottom end, weld on a collar and rebalance with stock rods pistons but new rings and arp bolts every where

I plan on either forging the bottom end later and getting a good oil pump and turning 9K rpms or building an RB30 with 25 head. I would be happy with either.

~Alex

[boosted98gst]

I say it all depends on what you're going to use the car for and how deep your pockets are. If you're already this far into the motor why not just refresh the bottom end and forged everything ? you have plenty of time before spring. If you're already thinking of going to a rb30/25 set up why are you even messing with this? Bottom line is how much do you want to spend or have? Personally I would never just take the bottom end apart just to make sure the bearing ect are ok. I would replace everything with good rod and mains, bolts, headgasket, good pump and collar , then have all the rotating mass balanced , then a set of good piston and rods. If you're wanting to turn 9+ rpm's your going to need some nice soild lifter nice cams and decent spring set up. A few years back I built my evo9 up and its not cheap no matter how you look at it, How many thousand of dollars are you wanting to throw at this car?

Modified by boosted98gst at 9:57 PM 1/24/2010
Modified by boosted98gst at 9:58 PM 1/24/2010

[Sil240]

+1 on that.

If you don't want to do a whole rebuild or you plan on switching motors. Change the bearings, rod And main bolts get your collar then you should be good till you get your other motor or rebuild this one. Then you can either keep this till you get your other motor running or sell it to fund you other motor.

[eh?]

You need to figure out if you want to do the RB30 or not. If not it makes sense to just do the full rebuild now while it's still the "low" season. If you do the RB30, reassemble this motor as is and don't spend more money on it.