fyi guys,

Well yesturday i picked up a RB30 for my conversion into my R33.
I will be using my RB25DET head on the RB30 block. So i started stripping the motor down, pulled the crank, pistons, girdle, oil pump, welch plugs & everything off the block. Now the RB30 block is going to be Acid dipped/cleaned and machined out a further .10 ontop of the .15 that it allready has. (total of .25)

Looking around on these forums i noticed a couple of threads of people spending $800 - $1200 on RODs! I pulled a piston out yesturday of the RB30, removed the gudgen pin and looked at the rod...

I then walked over to my old mans 900HP, 7 liter, 454 Big block chev (Also in peices on the floor) & compared rod sizes. Width of the Rods, SAME!.... Side wall strenth & Height SAME!!. Only noticable diffrence is that his are slightly longer. (witch in fact would make them weaker than mine because my rods would have a higer pressure tolerance) I will leave the rest for you too decide when its time for you to do a rebuild.

Anyways i am now at a stage were i am looking for pistons, i am not intrested to here anything about forged pistons. Alot of people arent aware of the cons about forged pistons, such as the amount of slop that a forge piston has (Clerance properties between the bore and the piston, & heating + cooling tolerances).If you guys all wanted to run 9 sec passes and were looking for no more than 100K then i would suggest running forgies. not for mild street cars.

Now, has anyone tryed using Thermo-pudic pistons (not sure on spelling)? i havent done too much reasearch into these pistons, but heard that it a very strong alternavtive to running forged pistons. And are still capable of running very high HP (600+). Some of the advantages of these pistons so far are that there heating & cooling properties closly match the stock pistons, and they are a very snug fit in the bore (prevents slapping up the bore on cold starts, unlike forgies that have to become warm then expand to provide the snug fit) This inturn reduces engine (cylinder) wear and will provide me with the drivability & performance that i am after.

Has anyone used these pistons or know of someone that is using them that has problems?

Basicly i am after so critism on the pistons, if there is any?

Thanks.

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well how much can the stock rb30et rods take? it must be around the 400+hp mark? cause ive got a rb30 sitting in the garage and i want to do this sooo much

Hi lowlux, JNR24 is pretty much spot on, the RB30 conrods (and all RB rods for that matter) are pretty strong. We regularly see 500 bhp RB30's with standard rods in them last a fair while. It really depends on the quality of the tuning, the bearings and the integrity of the oil supply. Better quality rods bolts also assist. (BTW; how did the rod bolts compare with the big block ones?)Plus using a lighter, forged piston helps the rods last longer.

Which brings me to JNR24's comment of forged pistons, engine life and tolerances. How many standard cars have forged pistons as standard? I can think of over 40 without any problems. None of them display the issues you refer to. Most of them have at least 100,000 kilometre warranties from their manufacturers.

The real issue is not how the piston is made, but what tolerances the engine is set up with and how the thermal expansion is handled by the block, cylinder liners and ancillaries like radiator, thermostat and water pump. You would also need to consider support mechanisms like ceramic-coated piston crowns and teflon coated skirts.

The piston manufacturers recommendations and data sheets are of considerable benefit when determining tolerances.

Hope that provokes some more discussion

Good point Sydneykid, i guess the modern car industrie does pretty much have the forged piston market covered. I Guess what i would have been refering to is a forged item would take alot longer to induce thermal expansion (on a cold start) inside the bore thus creating alot more cylinder wear as well as piston wear, as compared to these unknown Thermo-pudic pistons? As you know 80% of motor occores of the first flick of the key.

I guess its not so much of a big deal for this Block (considering the whole lot cost me a slab) but more for the fact that i am building this engine with not just performance but also "reliability" in mind. So of course to get reliability you need durability. Dont get me wrong, this motor should be capable of producing 500-600BHP, but its going to produce that power in a smooth and durable way (or as close as possable)

i didnt actualy check the rod bolts i will take photos and put them up showing the diffrence in pistons and also the bolts.

Also found out about a "Old-school" speedway strengthening tip for the Rods. Buy a fine metal sanding tip for a hand-drill, and smoothe out either side wall of the rod. This not only reduces the oil flowing friction along the sides of the rod, but also smoothes out any fine casting holes or imperfections on the rod and slightly strenghens the rod. Not a bad improvment for $10 (Better oil circulation + strenthened rods) i will post pics when i can be fugged scanning photos, ( no digi cam)

Sorry i got off a little there, but yeh... suggestions on the pistons?
Lowlux, this is the most worth while upgrade i think you can do for a R33. Got the looks, the solid bottem end. (Even if id does blow, its gona cost you $50 for a whole turbo RB30 bottem end)

You will see what i am saying when a post pics. the two blocks are identical.

Once last thing sydneykid, bearings. How much and what do you recommend. IAM GONA HIT SUBMIT NOW!!

the original nissan bearings work rather well IMHO, along with the Nissan head gasket.

although, you'd like to talk to matlowth (on here) as he's gone thru this on his R33.

Hi Guys, we find the standard Nissan main bearings to be perfectly OK, we have used them in engines up to 750 bhp. The big end bearings are not so good, we use Nizmo big end bearings as the standard ones don't seem to be able to handle the combustion pressures. It doesn't matter what oil pump we use, they always show stress on the top shell after as little as 3,000 kilometres.

Hope that adds to the discussion.

Polishing conrods is certainly an "old skill", works fine though.

quote: Now, has anyone tryed using Thermo-pudic pistons?

never heard of thermopudic pistons. Eutectic/ hypereutectic? relating to silicon content?

YES YES!!

wait tell me more, i belive these hypereutectic are the pistons my old man was trying to explain. Are they any good? pros cons?
heard good things about em..... but dont even know what they are...

sydneykid
what oil pump is best on the twin cam RB30 combo

Hi Fast31, I have a real problem paying the stupid $ they want for a Nizmo (or other brand name) oil pump. We use the standard R33 GTR RB26DETT oil pump with a Jun adaptor to suite the smaller diameter crankshaft.

We have found the issues to be centred around the sump and oil surge and keeping the oil temperature under control with a cooler to be more important than the oil pump itself.

Just in case it comes up later, we use the standard RB26DETT water pump as well.

Hope that helps.

ok then well my plan is this,

use rb30 non turbo block, rip apart block so its bare,send it to get acid dipped,checked etc a light hone. Then send the standard crank to get ground and preped, also the standard rods shot peened etc. Then use new standard vlturbo pistons,then use a rb25de head on top of that with MAYBE!!! using the rb20 ecu to control it all. Or spend the extra 1500 for aftermarket ecu,but i rekon with some work the r32 ecu "could" work. Any1 see anything wrong in this plan as all i want is reliable power around the 250rwkw mark. Oh and using a t04 with ext gate aswell

Hi Lowlux, suggestions follow;

RB30ET pistons with a RB25DE head would give a very low compresion ratio, about 7 to 1 if I remember rightly. That's gunna make a poor response, slow to build boost, dog of an engine. This is becasue the RB25 cylinder head has way bigger combustion chambers that the RB30 head. RB30E psitons will give 8.3 to 1 which is still not perfect, but much better than 7.

Don't machine the crank, it is nitrided, just balance it.

R32 GTST ECU's are chipable, so no problems with using that.

Why would you use an old technology turbo like a T04?

Hope that helps.

hmmmmm so what if i used non turbo pistons with better rings? also i thought using the non turbo rb25 head would make more compression than a turbo rb25 head? or is it the same?actually i would be the same wouldnt it, also what would be the best compression ratio? around the 9's? and using the t04 is cheap thats why lol i dont wanna go spending $2000 on turbo, well if i can get away with r32 ecu then maybe spend more money on turbo but who know,i want to build the bottom end first then make decisions from there. But help on the compression side would be good what about a slight machine the top of the block?

Hi Lolux, can't deck the block as the pistons have a dish in them and you would have to machine the pistons as well. This would weaken the ring lands.

I prefer to use around 9 to 1, makes a much more responsive engine. Plus, with the current generation of turbos, you don't have to run high boost to make good power. So you don't have to decompress an engine like you use to.

Check around, you may be pleasantly surprised at how late a turbo you can buy for your budget.

Hope that helps.