Boost and Piston Damage

[KAOS]

Ok this is the deal. I want to make at least 500HP at the wheels.

The car came over with an hks 30/37 on an adapter on the standard manifold. 650cc injectors, greddy plenum, greddy external gate. hks mild cams (not sure exactly on specs but they don't look, nor did it sound, very beefy). sold the hks turbo as I had the t78 33d there. Going for the 3L bottom end, and I am basically a little stuck on what angle to take on things. So much different advice. You guys are helping heaps.

So the recommendations are so far: Arias pistons with different rings (as mentioned earlier). Still not sure on rods etc. I might try and chase up some GTR bits (rods and crank). What about this cryogenic freezing deal to strengthen the RB30 rods and crank etc? If you guys can help me out with the info, I'll keep you updated at each step. Cheers for all the advice and discussion so far. I'm learning heaps.

[KAOS]

Just a quick msg. If it isn't really worth while having the variable timing, should i worry about adapting the rb30 block to suit it. Can you leave it out?

[Sydneykid]

Hi KAOS, thanks for the info on your requirements. My suggestions follow;

- Loose the VVT, waste of time on a big horsepower engine

- The camshafts you have are possibly 256 degree low lift (around 8.7 mm), you could upgrade to HKS 264 degree cams for inlet and exhaust, there are two types, go for the high lift (around 10.5 mm)

- if you can get a HKS camshaft kit (of the above spec) with valve springs cheap take it, if not Iskanderian valve springs are the go

-adjustable pulleys on both camshafts, we use Jun or Toda

- the standard RB30 crank (as with all RB turbo cranks is very strong) leave it alone, other than a micro balance

- Use Carillo conrods, the RB30 standard conrods won't handle the power regardless of what you do with them. The previous posts tell you why.

- O'ring the block, standard Nissan head gasket, compression ratio needs to be around 9.0 to 1, not much less or you will loose driveability and increase lag

- balance all of the up and down and round and round bits

- use the RB25DET oil squirters for piston cooling, if the RB30 block does not already have them

- loose the standard exhaust manifold, Spoolup has a good one (Trust I think) for sale for around $800

- I prefer JE Pistons over Arias, but both are OK, stick with 87 mm or 87.5 mm depending on price. Previous posts explain why.

- R33 GTR water pump and oil pump (Smokey33 always has them for sale cheap as Sub Zero throws them away when they do a mega engine).

- Use ARP bolts for the main bearings and head (Carillos come with ARP rod bolts).

- Use the RB25 sump but increase its capacity, around 7 litres is good and use an oil cooler.

- Standard Nissan main bearings and Nismo big ends, previous posts explain why.

- match port the cylinder head and the manifolds (both inlet and exhaust)

- I would use a Motec ECU (M8000) on an engine with this sort of output

- PWR radiator as the standard one simply will not cope

- Twin plate clutch, at least, we use OS Giken

- Injectors at 650 cc should be OK, previous posts explain why

- adjustable fuel pressure regulator, may help to stretch the injectors if necessary (not more than 10%)

- Bosch 044 Motorsport fuel pump or equivalent with capacity for 330 litres per hour minimum. We use 2 GTR pumps feeding off a surge tank with a third GTR pump as a lifter.

- Check the fuel rail and plumbing for this capacity

- at least 3.5" dump from turbine and exhaust 3" or more

With a T78-33D it will have 600 bhp easily at around 7,100 rpm and 1.5 bar, as long as it is tuned well. Don't rev it over 8,000 rpm for long periods due to the crankshaft harmonics, previous posts explain why.

Hope that helps.

[Sydneykid]

Hi merli, Steve started this thread, lets ask him whether he thinks it has deteriorated?

[Merli]

Originally posted by Sydneykid

Hi merli, Steve started this thread, lets ask him whether he thinks it has deteriorated?

It has definitely lifted with the absence of Peewee

[GTS-t VSPEC]

I think that the majority of the information being given here is of a very high quality and hope that more useful information comes out of this thread.

See'ya:burnout:

[MIKGTR]

So as long as your engine has a well designed cast piston and you stop detonation there is no need to use forged pistons.

I've mainly worked on motorbike engines & I know many tuners say the fastest way to detune an engine is put forged pistons in as they are usually heavier than cast, unless you use well made forgies like cosworth or Japanese factory pistons, not Wiseco, Arias, JE etc.

Has anyone here measured the weight of a stock RB or SR piston compared with a forgie, I'd be interested to know which was lighter.

[GTS-t VSPEC]

I was pretty sure that the forged pistons were just as light, they are made from aluminum. I have a set which will be going in. All forged pistons are made from the same material, so the Japanese ones are no better than those made in the US.

See'ya:burnout:

[MIKGTR]

Its not really about what there made from, almost all pistons are made from some form of aluminium alloy, cast or forged. Not all forged pistons are made from the same material.

The cheaper "off the shelf pistons" such as Wiseco, Arias etc are generally heavier than custom made forged pistons, and as I have been told, standard cast pistons.

There are good reasons for using forgies such as changing comp ratio & capacity and Wiseco Arias etc are all good quality items.

What I'm getting at is what is the point of using forged pistons unless you are going oversize or changing comp?? Because using forged pistons may make your engine produce less power.

Thats why I am asking if anyone has weighed them.

[Steve]

I think I have learnt more from this thread than the combination of many more previously. Thanks all who have contributed.

Sydneykid, in your reply to KAOS, you talk about using 10.5mm lift. Would this require changing to solid lifters? Also are there any piston/valve clearance considerations?

Also,

What are the advantages of solid lifters v's hydraulics and vice versa - there seems to be alot of view around of 'solid are best' or 'I prefer hydraulic lifters' but I have never understood why exatctly. the only info I have ever found was that solids were better for high revs, stronger valve springs and higher lifts? Is this right?

MIK GTR, I think I know where you were coming from, what I was wondering myself. With a conservative tune, just when do the pistons start saying enough?

thanks again to all, some great reading.

KAOS, it would be good to hear what you are doing with the build and decisions made, lessons learnt. Not too many people go the whole nine yards, I am sure it will be interesting

Cheers

Steve

[KAOS]

Thanks heaps for the info Sydney Kid. You've already been more helpful than anyone else I've talked to. Cheers for that. I'll probably have a few more questions for you soon if that's ok.

Merli - This thread is the most informative I have ever read. They're actaully explaining the concepts with proof etc.

I'm loving it. Thanks again ALL.

[KAOS]

Steve - Hopefully I won't have to learn any lessons the hard way....anymore. Budget is stretched already.

In the head, either side of the valves there are two large lips and someone put it to me to grind them out to make it semi-spherical.

Sorry for the bad explanation. Any ideas?

[Xeron]

Just one thing i'd like to add, if your going to O-Ring the block, and probably run a copper gasket, wouldn't it be more adviseable to also use head studs instead of bolts.

And about VVT, Vtech and all the different incarnations, they improve driveability, not power, and you never run a huge undriveable cam in a turbo engine really, so dont worry about it.

[Sydneykid]

Hi guys, lots of questions, not much time, so let's try one answer at a time.

Solid lifters versus hydraulics.

Hydraulics are used to lower the servicing costs because they require no adjustment. They maintain the correct valve clearance using the engine oil pump to provide pressure to keep them pumped up. They achieve this via 2 small holes in the head that line up with holes in the valve bucket, every time the valve closes the oil flows in and out of the bucket. This happens in the cycle when the lift from the camshaft comes off the valve, and thus maintains the valve clearance at or close to zero.

A solid lifter has none of this, the valve clearance is adjusted by removing the bucket and placing a small spacer (shim) between the bucket and the valve stem. As you can imagine this is very time consuming (labour expensive) for 24 valves, plus you have to have a range of shims which are made of hardened steel (expensive parts).

Having an understanding of this, the common problem with hydraulics is when the rpm rises there is not enough time for the oil to flow into the bucket and the valve clearance opens up. This results in less valve lift and poorer performance and rattling valve gear. Conversely I have seen cases where the oil gets into the bucket but can't get out. This increases the valve lift until the valve stays open and the piston hits it on the way up. Not nice.

Since hydraulics are really a bucket within a bucket, it is possible to run out of space when using high lift camshafts. So that can be an issue. I have never seen a problem with hydraulics and stronger valve springs.

I think that answers Steve's questions.

One more before I go to earn some money, to buy some bits....

Weight of forged pistons from MIKGTR...

Most motorbikes I have seen use a high pressure cast pistons (as do Honda cars) these are a piston in which the molten aluminium is pored into a mould and pressure is then applied. It makes them (denser) stronger than a gravity (or low pressure) casting which has little or no pressure applied. A normal cast piston would not be able to stand the rpm in a bike.

A forged piston is denser again and therefore stronger as the aluminium used is not molten and is "forged" under very high instantaneous pressure. This is a more costly process than casting as used by the OE manufacturers.

So in order to make a gravity cast piston strong enough to handle a cars rpm and power output (combustion pressure) more material is used in their manufacture. The break even point in weight is when the cast piston has to have so much low density material in it that the weight becomes higher than the forged piston (with its high density material) for the same strength. A turbo engine is a good example of this, where the cast pistons have to be very strong and therefore heavy.

Getting back to the question....

I have never seen a cast piston in a turbo engine that weighs less than a forged piston of greater strength. In fact , typically the forged piston will be 20 to 25% lighter.

As MIKGTR points out, this may not always be the case with a N/A motorcycle pressure cast piston. A forged piston of the same strength will be lighter, but one of superior strength (or larger size) may in fact be heavier.

So if you have a N/A motorcycle engine in your Skyline that has pressure cast pistons, it is possibly not worth going to forged pistons. If you have a Skyline with a Nissan RB turbo engine and gravity (or low pressure) cast pistons then forged pistons offer both strength and weight advantages.

Hope that adds to the knowledge base.

More answer later, if time permits...........

[Sydneykid]

Hi guys, just a quicky..........

As far as my research has gone to date, I have not found one Japanese tuner (HKS, Tomei, Jun, Toda, Trust etc) that make their own pistons. I have found they all come from the piston specialty manufacturers like JE, Arias, Wiseco, TRW, Cosworth, Ross, Mahle etc.

If you want to check this out for yourself, read through the huge number of articles and videod visits to the Japanese tuning shops and see if you can find any evidence of a piston forging shop.

Piston forging equipment and technology is very expensive and requires large quantities to be made to justify the capital cost. I don't believe that the Japanese tuning shops would have that sort of volume now or in the foreseeable future.

Ditto conrods and crankshafts, they also appear not to be manufactured by themselves, but by the specialty houses around the world. It is well know that Harrop's make such stuff for a number of tuning shops to brand as their own.

Bottom line, you are most likely paying for the name, not extra quality.

That might result in few more posts...............

[GTS-t VSPEC]

Sydneykid,

This was the point I was trying to make earlier to MIKGTR, that the Japanese pistons are made from exactly the same material as the US ones.

Most tuning houses specify a design, and then get the US companies to make them, and stamp there name on it.

I have seen the companies like Tomei do make there own cams, but no other evidence of part manufacture.

See'ya:burnout:

[Xeron]

and then uve gotta raise the question, are forged pistons for RB's expensive cause of the limit run size, or is there a huge markup when the tuner shop gets them. (for instance u can get TRW forged pistons for a v8 for as little as $44 each, thats no joke).

Any of u ever tried ringing up the factories and asking for a piston to match RB specs?

[GTS-t VSPEC]

That sounds very cheap. That's why I buy pistons from the US, same quality, half the price.

See'ya:burnout:

[Sydneykid]

As Xeron asked,

"then uve gotta raise the question, are forged pistons for RB's expensive cause of the limit run size"

Yes, but keep in mind they will always have shorter runs than the Yankie V8's that are made by the thousand. Not a lot of Skylines in the US.

"or is there a huge markup when the tuner shop gets them"

In my opinion this is much closer to the mark. Take JE Pistons which from JE are a little less than half the cost of the same piston from "unnamed" Japanese Tuning Shop.

Is it time we started a "who makes what for whom" section on the forum?

[BU5TER]

I'm really confused now about the forged pistons by saying your only paying for the brand name isn't it like saying the Garrett turbo's are the same as the HKS turbo's its only the name you pay for?....Brett