Power hunting on my R32

[HaZe]

Hey guys.. just looking for a few opinions at the moment.. i'm considering going on a powerhunt soon for my R32.. and i'm undecided on which direction to go in.. i've been hearing all about rb24's, and rb30's running rb26, or rb25 top ends.. it's all a bit confusing.. anyone got any hard data on what can be achieved on these combo's, and what kind of mods woud be necessary to get the go?? i'm not looking for huge figures atm, but want a package that i can get serious with later .(serious=350+rwkw) Any idea's ???

[meggala]

my web site would be worth a look

http://meggala.com my thoughts are there

[Fast31]

you will be better off going large on capacity then, like a 3 litre bottom end, with either a rb25 or 26 head

[Sydneykid]

RB20 has 78 mm bore and 69.7 mm stroke for 1999 cc's

RB25 has 86 mm bore and 71 mm stroke for 2476 cc's

RB26 has 86 mm bore and 73.7 mm stroke for 2570 cc's

So the RB20 has a 8 mm smaller bore which means smaller valves

which is why it doesn't flow as well as RB25's or RB26's. You can not put the bigger RB25/6 valves in an RB20 head. Also the RB25 or RB26 head can not be used on a RB20 block, the bore (78 mm) and combustion chamber (86mm) mismatch would make this unworkable.

Hope that helps

[Sydneykid]

Hi HaZe, 350 rwkw is around 560 bhp. That's way beyond the economic power output for a RB20DET. Based on previous experiences;

We buy complete, rebuildable RB30ET's (Commodore VL Turbo) without accessories (turbo, a/c, p/s, alternator) for less than $A600. A complete RB25DE costs around $A1,300. We sell the bottom end of the RB25DE for $A400 and the head off the RB30ET for $200. So the net cost is $1,300.

The RB30ET is 3 litres (86 mm bore X 86 mm stroke) This is the same bore as the RB25's so the head fits straight on, using the RB25 head bolts. For racing, we change the rods to forged and the pistons (87.5mm for 3,104 cc's) also to forged ones. We use the standard crank which we balance and check for straightness.

The extra 628 cc's (25%) capacity over the RB25 (2,476 cc's) gives more torque, both on and off boost, plus it makes good boost earlier. The trade off is that it does not rev as well as an RB26DETT, but the total cost with a single turbo is way less than half for the same amount of power. Plus, because it does not have to rev as hard, it doesn't wear out as quick.

If you can do the engine work (not machining of course) yourself, the cost per Kw is unbeatable. If you have to pay someone to do it all for you, then it is not as attractive. Buy a low K's RB25DET and stick it in would be my suggestion. Leave the internals stock & then bolt on the go faster bits progressively. %THis would give you 450 bhp.

Hope that helps

[Sydneykid]

So if you want to go for the 560 bhp, this is the sort of stuff we use....

* the turbo (say a Garrett GT30408BB) would be $3,000

* wastegate (a 45 mm Progate) would be $800

* set of equal length exhaust pipes, wastegate pipe & dump $1,600

* Camshafts (Jun 264's) $1,300

* Headwork $800

* Conrods $900

* Forged pistons $1,800

* Greddy drag intercooler $1,800

* balance and assemble $1,000

Total $13K.

Now at that sort of power the R32 GTST gearbox ain't gunna last, a R33 GTST one would be OK. They're about $800. Plus it will need a good clutch, a twin plate OS Giken is what we use, they cost $3K.

Hope that fills in some more gaps.

[HaZe]

Woah, thats a pretty extensive and accurate shopping list.. lol.. thanks.. gives me some food for thought.. might have to go get me an engine stand and an rb30 to start playing with...

[HaZe]

Hey Sydneykid... it sounds like you have a workshop?? is that so?? if so would it be possible to source the block and head thru you?? Also.. is it worth going a twin turbo setup? i have someone who can design, engineer and build any custom intake/exhaust manifold work.. i would just have to get some specs and pics of something similar, then get him to fine tune the design.. anyway.. thanks for all the lovely info.. not going to bothe rdoing any more mods to my little rb20 now.. might as well save for the real thing.