Refreshing a RB26 ; What would you do?

[cobrAA]

So, after 2 attempts to buy forged block.. I spoke with my mechanic and he told me

'' Alex, you don't need to be forged for your power goal ( 500whp !MAX! 550WHP), the stock internal can take it and secondly, for daily, a forged built don't last ''.

So I made my mind, I don't need to be forged. Not for 95% of daily and 5-6 drag night per year. 2nd reason; I'm seriously thinking about paying a house in 2 year so I can't afford to put 80% of my paycheck anymore in this money pit. And before I reach 550whp, I will need a standalone ECU and new turbo and I'm not down with this.. I love how responsive is my engine right now.


So what would you do for a simple refresh and cost-effective mods?

I was told :

New gasket kit 200$
Metal head gasket 250$
N1 oil pump 200$
Machine my crank 300$
Piston ring ( is it really needed? ) 200$
I was told ''planning my head'' would be a good idea.. my friend did it for 350$

Total: 1500$


My timing belt maintenant was done last summer + an ati damper has been fitted at the same times.

[amnash]

the rings being needed would depend on your compression before hand?

[Skym]

Can be expensive or cheap as you make it.

Cast pistons are good for around 100hp per cylinder x 6 = 600hp at engine. But can take more on E85 fuel or similar due to cooling effect of fuel.

With budget forge build, can change to Tomei forged pistons with stock I beam conrods (crack test, shotpenn, etc and use 6x good conrods, just like Nismo do with N1 engines) + ARP rod bolts, aftermarket bearings and 700hp at engine is possible on dyno with stock block, Tomei Poncam Type-B, adjustable camgears, Tomei bronze valve guides, etc. At Nurburgring, 500hp at engine was the reliable setting with N1 engine (upgraded stock RB26 engine) for a 24 hour race.

This can be controlled by stock ECU with Nistune. Group-A R32GTR had 640hp with stock GTR ECU controlling it in Japan.

But for basic boost up to take advantage of stock turbo's, stock engine -

Nistune for stock ECU
Apexi or similar panel filter in stock airbox
Full exhaust from turbo's
Tomei Poncam Type-B
Boost controller
Clutch
Tomei or Nismo sump baffle plate (helps to prevent oil starvation problems on drag strip due to oil moving to rear of sump when launching and is best done when engine is removed from car)
E85 or similar gas (can get 50awhp+ gain with ECU tune to produce the hp on dyno or dragstrip) but might need bigger injectors, fuelpump, Z32 AFM x 2 + Z32 AFM plugs.

[cobrAA]

Skym your such a source of knowledge :P

However, everything you listed regarding mods are already on my car except poncam ( will buy them this winter) and oil baffle.

As for fueling.. best thing I found is Water-Meth.. and it's sitting in my closet ready to be installed.

[evilgtr]

Skym that's a great reply you summed up pretty much everything. The only thing I would add is that power goal won't be achieved on stock turbines and a simply swapping the ecu for a oem R33 Gtr ecu is a cheap option that will give your tuning precision in the higher hp range due to it having twice the maps making it easier to fine tune.

Also Alex your builder told you forged engines won't last as daily drivers ? I'm interested to hear the reasoning behind this.

[cobrAA]

I'm not running on stock turbines

I can ask him but I'm sure someone know the reason behind this that could chime in. I know it has to do with the difference in metal and the fact that the engine is less tight ( cleareance wise)

[Skym]

Thank you for the kind words, but I don't know that much. Just know the basic boost up menu for RB26.

Also it's what they do with 400hp Nismo S-tune engine, but use stock R34 turbo's instead of stock R32 GTR turbo's and have metal headgasket -

http://www.nismo.co.jp/omori_factory/original_menu/engine_m/s1/index.html

As far as I know the S1 cams are very mild, like 250 duration intake, exhaust (Tomei sell cams for GTR that are this spec). But gives stock like powerband and more peak hp (400hp).

R tune is the N1 spec engine with N1 turbo's, R1 cams, etc -

http://www.nismo.co.jp/omori_factory/original_menu/engine_m/r1/index.html

Also might want to change intake gasket's to Tomei steel, as they can blow at higher boost levels and fit a Tomei metal headgasket at same time while head is off.

R33 GTR ECU has better control over fueling and why it's used over stock R32 GTR ECU. Also they change to R33 o2 sensors to match the R33 GTR ECU, as shown on Nismo website.

[NismoS-tune]

I've seen guys make 500whp as cheap as $10k in mods/labour, (stock head/exhaust/intake pipes/intercooler and so on!! you don't need fancy pipes/gauges and sump plates to make good power but you should when you want extended reliability. That's why some builds make only 500whp with $30-60k into em.

As for the "forged won't last long on the street". Ask him about the 2JZ, those are forged from the factory

[Skym]

I see. On dyno, but when used off dyno, different story. Cams help with same hp but less stress on turbo's and engine with lower boost level. Also ECU tune plays role in reliability.

[newalliance123]

Maybe his mechanic is suggesting that a lot of people who rebuild there engine have a failure after. Probably due to short cuts being taken in the build process or large clearances being accepted or the tune they were running.

It would be silly to rebuild an engine without new piston rings. Stock rings are going to run you maybe 200, but you can purchase a forged piston kit for 700-800 that comes with piston rings. I'd say at least get the piston kit to take a little punishment from detonation and it will come with the rings you are going to require.

Just a thought.

[Skym]

Forged pistons can take a while to expand and seal compared to stock cast pistons, so forged pistons slap around more until engine is warm. Most racecars with forged engines are warmed up on the spot before being used on racetrack, etc. That's what my mate with GTR racecar, forged engine does and he drives it very hard on racetrack.

It's the ringlands that usually fail on stock pistons. N1 pistons supposedly have stronger ringlands. But ringland failure can be due to high boost level with high compression or wrong sparkplugs, engine knocking due to pushing limits with ECU tune.

[BenC]

So, after 2 attempts to buy forged block.. I spoke with my mechanic and he told me

'' Alex, you don't need to be forged for your power goal ( 500whp !MAX! 550WHP), the stock internal can take it and secondly, for daily, a forged built don't last ''.

So I made my mind, I don't need to be forged. Not for 95% of daily and 5-6 drag night per year. 2nd reason; I'm seriously thinking about paying a house in 2 year so I can't afford to put 80% of my paycheck anymore in this money pit. And before I reach 550whp, I will need a standalone ECU and new turbo and I'm not down with this.. I love how responsive is my engine right now.


So what would you do for a simple refresh and cost-effective mods?

I was told :

New gasket kit 200$
Metal head gasket 250$
N1 oil pump 200$
Machine my crank 300$
Piston ring ( is it really needed? ) 200$
I was told ''planning my head'' would be a good idea.. my friend did it for 350$

Total: 1500$


My timing belt maintenant was done last summer + an ati damper has been fitted at the same times.

Allot will depend on the current state of your motor

If your compression is good don't even take the pistons out. The rings bed in a certain way and If they go in different they likely wont seal the same. A hone and new rings wouldn't be a bad idea though. Forged is a better idea

Resurfacing the head and the block isn't really necessary unless it is out of spec. Again not a bad idea to ensure a good head gasket seal. Should only cost around $100 each though. But then you should get all the passages cleaned to get any metal shavings out

ARP rod and head hardware is a good plan. If the crank is coming out the bearings should be replaced too. A solid tune will be needed to ensure the cast pistons don't piss off

[NismoS-tune]

But remember, good compression numbers don't really tell everything about the condition of your engine. You could have bearings near failure or a rod bolt easing up and comp is still good. Which is why I decided to rebuild my 20 year old engine though it was 160-165 all across, rather than chancing a fail that could be irrepairable. So the tuner and I agreed to stop at 300whp as a base tune till my engine was built. Serious power requires serious builds but I wouldn't mind going 500whp on a nur spec engine though it's not forged, it's new, not 20 years old and tired. I'd say the cheapest and easiest thing to do would be to buy a nur long block and throw it in. they can take over 500whp and I THINK they are less than $10k new, maybe $7k?

[cobrAA]

We'll see if it hold up..

[Terrh]

For starters, this is a GTR. There's ways to cut corners and save a buck or two but there's no way to do it "cheap". If you can't afford the car, sell it and buy something cheaper that's just as fast. You'll enjoy it far more in the long run when you are out there driving instead of staring at a broken GTR.

Why is the engine coming apart? Just from what you are replacing I'm going to guess it's due to a spun bearing. If so, here's your list of actions:

Get the crank out, send it out to be checked for cracks and machined. If they find cracks, Go buy a new R34 crank, they're reasonably priced nowadays. If it can be machined, and hasn't been once already, go do it. Get a crank collar installed at the same time. Don't buy a used crank unless the seller has had it checked already and will guarantee that it's decent. I went through 3 crankshafts before I found one that passed the crack testing.

Second, Go buy forged pistons and rods. Ebay is cheapest but some of the vendors on here have pretty good pricing too. Can always check the forum for used pistons/rods too. If you search around you can find a combo (with rings and everything) for about a grand. They last a long time if the engine is put together right. My engine had 45,000KM on it when I pulled it apart and if I hadn't lost a valve guide it would have still been fine. Wiseco pistons and Eagle rods are the combo I'm running, they seem to work great. They were good enough for that guy building the 1500HP VG30 so they're good enough for me.

Getting the block and head planed shouldn't cost you much ($50-$75 each) and may or may not be necessary - if they are straight already, don't bother. If they don't pass the straightedge test, it MUST be done if you want the headgasket to last. If you're using a metal headgasket (I would!) the surface finish must be per the manufacturer's specs if you want it to be optimal.

the N1 oil pump does a fine job, I had no oiling issues with it.


If your head is working just fine it's up to you there. I wouldn't even take it apart if you are trying to save money, just look at it closely, check the combustion chambers for leaks (about $50 at a machine shop or you can DIY), and if everything checks out then put it back on the new bottom end and call it a day.

If you open up the head for ANY reason replace the valve guides. They're about $150 on ebay for supertechs and if you have a chunk of a stock one fall into your engine you'll be back to square one and rebuilding the whole damn thing again. The OEM valve guides are powdered metal and very brittle. If you decide you're going to get in the head it's not a bad idea to think about getting it ported too. PM me if you want the name of the best guy at skyline heads in canada. His pricing is VERY reasonable all things considered too.

This kindof goes without saying too but replace all the gaskets/etc that come in the rebuild kit. And any hose that looks iffy. And ALL the hoses at the back of the motor that you can't get to when the engine is in the car. Have a look at your clutch too. Now's the easiest time to replace it.