How Strong Is My Rb25det - I need a few opinions  

youbUTEless 33

300hp is not a big build anyway so i dont see any need for most of that stuff, if you can get your hands on a power fc and some spitfires, highflow is a good way to go if your not looking for massive power.
rb's are very strong motors as long as you keep the oil topped up, higlflowed, a good intercooler set up, good exhaust and intake, spitfires and boost conreoller, with FC will be more then you need IMO

pipster11

you will prob want more power once its tuned
i would forge it then when you want more power the only think that needs changing is the turbo (espcially seeing as you have removed the engine)

86TX5

Would it be worth doing the headgasket while the engine is out?? What you guys think? Its done 100,000ish

the_random_hero

Headgaskets don't need replacing at set intervals. Not confused with having to change timing belts?

bop001

hey mate. im in your boat too. im doing a full rebuild but with a wilder setup.

the block, considering it is full of good parts shouldnt have any problems if run in/ built properly.

however be warned. going for 40thou pistons over 20thou pistons has its risks. if for some reason u fark up the bottom end, the 20thou bore can be re-bored out to 40thou. if u stuff up the block, your up for a new bottom end and associated parts.


yes, the motor will be safe, considering the turbo will be the restriction.
with a properly forged engine with all the right gear u can push 600+ rhwp, just depends on the combination, tune, and build quality.

goodluck, if your looking for a full rebuild, your looking at about $10000 for the rebuild including labour, excluding bigger turbo.

youbUTEless 33

ohh on that note, how do you know if the belt has been done? because i have a sticker with some jap writing on it and then the number 100 000k on the cover, i bought it at 130k and i dont know if its been done, ideas?

lol im not hijacking i promise

35NIK

if your rebuilding it, Strap a t04z on the side with a good ecu & tune & expect a drap weapon!!!
if your only after 300rwkw, dont bother rebuilding it, just a set of cams on the inside will do.

86TX5

haha no im not confusing the headgasket with the timing belt. What im asking is if im going to be running bigger injectors/fuel pump, about 14psi blah blah blah it might be worth while replacing the gasket witha multi layer steel one. Ultimately all im aiming for is about 300 hp so it really doesnt seem worth while to spend all this money on a forged setup. And whoever pays 10k for an engine rebuild clearly isnt doing their research. I have sourced new parts to forge the block (main and head studs, pistons, rods, mls head gasket, bearings and so on) from suppliers for a total of around $3500 and talked to a well known performance shop who will assemble and race prep the whole engine, including head porting for just over $3700, or $2900 without head porting. People just dont ask around. Ive only talked to 2 shops, could prob get it done cheaper again.

09ONE

If you do it properly then $10K is about what it costs.

3K in parts??? Not using a bottom end?

Either way you won't need to rebuild if you are just using a highflow. I have been through a couple of RB25's which held togeather for about a year with 380rwhp under track conditions, but 300rwhp would have seen them last a lot longer.

86TX5

How does it cost 10k?? Unless you are doing valve springs, cams, forged valves, turbo, intake manifold and all that shit to the head there is no way a forged bottom end with new gaskets/bearings will cost 10k with labour/assembly.. people obviosuly dont look around and just go to the first shop they come across

bop001

pistons- 2000-3000
conrods-700- 1400
big/main end bearings= 800
ALL machine work, blueprinting, balancing, weighing, honing, boring bla bla- 1200-4000 (add more for major head work)
labour including removal and fitment of engine= about 3000-4000 at MAX
water pump-500
oil pump- 500-1000
crank case collar for the oil pump-100-200
timing belt- 200
belt tensioner/pulley kits etc- 200-400
oils/lubricants- 300
headstuds- 200-300
cometic head gasket- 300-400
and dont forget once its run in, it needs a service so add another 100-400.



still need a calculator?

and i havent even gotten into major cammage and headwork, nor turbo upgrades and associated parts.

the OP only wants 300hp. so most of the above is not necessary. just keep up the mainenance.

86TX5

ARP Head Stud Kit - $299.20 quoted
ARP Main Stud Kit - $286.00 quoted
ACL Race Bearings (Main) - $132.00 quoted
ACL Race Bearings (Big Ends) - $96.80 quoted
N1 oil and water pumps - $990.00 quoted
I picked up new ACL Forged pistons for $800.00 not quoted
I picked up new Eagle Rods for $800.00 not quoted
Timing belt kit with tensioners and pulleys, cam and crank seals - $275.00 quoted
Or optional gates racing belt $120.00 quoted
Cometic headgasket $300 quoted
Crank case collar $100 quoted

Your budget $5700 - $12,200 without servicing(already have my own oil and service my own car) and engine removal (as mentioned the engine is already out)

My budget - $4079 without servicing and engine removal

It took me only two emails to two different suppliers to get these quotes. I spent 3 days searching boostcruising/skylines australia and ebay to find my brand new unused pistons and rods for $800 each delivered. It just takes a little looking to get the right price, im not sayin the prices you gave me are incorrect, im sure a lot of shops do sting people for that kind of money. But you really gotta look around, why just go to the first shop you see and say build me an engine?? This sort of thing takes reseach and because I did do some research I have been able to get all my parts cheaper... anyway im not here to prove any points, just wanted to make you aware that it can easily be done for like $4,000 in parts(not $3,500 im sorry).... and as mentioned earlier $2,900 for assembly, and I have only spoken to two shops so far...

raZ

Not worth it for 300 HP just get the highflow, z32, injectors, afm and a nizztune should be nice and safe as most people with highflows can get 250kw with tunes etc.

09ONE

Ok so you want to start crunching numbers...

Firstly has your engine been built? Because mine has and there are numerous costs you are not considering.

Also, your choice of parts leaves a little bit to be desired but I know you are not chasing much power. Factor in some more parts for the head, items like exhaust valve guides, stem seals or actually just a full VRS kit for the head.

$600 I think you mentioned earlier as head porting? I am not exactly sure what that gets you but it's like 3-4hrs of porting. I spent 24hrs worth of porting on my head which is really fuck all in the scheme of things. And who is paying the machine costs or have they been included in the price of assembly? Machine costs can add up real quickly.

It's almost impossible for the shop to quote you accurately unless they already have the engine in bits and have already sent it to the machine shop, as they won't know if your block needs to be over bored (scratched cylinder walls) or just re-honed etc. Did you make sure that the pistons you bought actually match your block (sizing are they stock or 20thou, 40thou etc) Have you checked the thickness of your head gasket and do you know the "crunch" when the head is bolted down? Have you compared your head gasket measurements including "crunch" to the pin height/deck height of the piston?

You say you have done your research but there is so much more to it then just going to a shop and saying "here is my engine and some parts I bought off EBay, build me a good engine". I researched my build for over 18months before I actually started it. Do you even know what your static CR will be?

175ONN

What he says is completely true. I'm currently in the process of rebuilding my engine, and although its not an rb25 its the same concept. You will realise when you take your engine in to get rebuilt that numerous unexpected costs will pop up. So much shit in your engine may be worn or simply stuffed and you may not know. Believe me you cannot put a price on a rebuild until like said above that its in peices at the machine shop. There is just so many variables and shit in the engine that it makes it close to impossible to predict what may or may not need to be done.

Anyway my engine is costing me approximately 12gz, but thats because I have requested for extensive head work including solid lifters, valve guides, high lift cams and valve springs, they may not seem all that expensive but when the entire head consists of Tomei parts it starts to add up reall quick.

If you're only aiming to rebuild your bottom end, which is pistons, rods, bearings and headgasket. I would put aside a good 6k and not expect much in return from it. This will include parts and labour. You're forgetting that when you take the head off the bottom end that it must receive a recondition and crack testing etc. This is a 100% must and costs around 600-800.

Good luck.

86TX5

Yeah fair enough. Thanks for your opinions

09ONE

12G's is a good budget I think. The costs rack up at an insane rate but you know it will be worth it and to be honest this whole engine building thing is somewhat fun.

I have had to "adjust" my budget 3 times during my build and each time it was by the amount the OP was looking to spend on his entire engine...

liampire

Don't wast your money on rebuild for a puny 300HP. An internally standard rb25 with good compression will put 400HP to the wheels reliably with supporting mods.

pipster11

^^^ x2

thats what i have been thinking as the thread has been going on

just get some new rings and maybe bearings and slap it back together (new pistons if you want cos you already have them but then you'll need block boring and honing and all that crap)

seems like a lot of money to spend for 300hp when you could run that with just bolt on mods

bop001

disregard the above statement. u DONT NEED TO OPEN THE ENGINE.

on my old engine with a gt2540, fuel pump, pfc, injectors, afm, basically everthing bar the internals, i was making just shy of 400hp on 14psi.

breaking open an engine for 300hp is a waste of money and time. just check the compression, service every 3000kms, and change sparkplugs often, and switch to BCPRES7's and u will be fine. incorporate a basic h/d clutch and u will be laughing.

but with basic mods u have 250hp......y bother opening up the block for another 50 when u dont have to


many apologies.....i meant a gt3540

rb30r32

for 300 rwhp the bottom end should b fine provided the engine in not detonating. most of the rb25s ive seen pushing 400rwhp dont seem 2 last very long(not saying all) . an rb25 engine that is making300rwhp may only last 1 drive if severe detination was present, where as its probly possible to push a rb25 to 400rwhp for a year or 2 and have no issues. when u hear that pinging sound. (u cant always) just think of it as a hammer smashing into ur pistons . personally i keep an eye on detonation with a knock detector around 250 bucks . witch is bugger all compared 2 a 10,000 dollar engine.

86TX5

Sounds good. I basically just wanted a guideline to what I need and dont. But im quite clear on what the rb25 can handle now after doing a bit more homework. Its getting water pump/timing belt/ heavy duty clutch/ engine mounts (shagged) and a few gaskets here and there. Then il slap her back in!

liampire

That sounds like a good idea. Save your dollars and when you do get internal work done to your engine at a later date then make it worthwhile.

isajlo101

Hey Jamie - I have a 93 Skyline GTST with the RB25DET motor still stock, the stock gearbox and diff. All I have done is added a new Plazmaman inlet manifold, Plenum intercooler piping kit, Plazmaman billet fuel rail upgrade, THR injectors, HKS camshaft, HKS cam gears (slide pulley), Link Atom G4 ECU, High rise turbo manifold with Garrett turbo (Toned down to 14 psi), custom dump pipe, custom intake piping, High flow Cat converter, custom intercooler piping - Dyno pulled 290 Kilowatts (388 Horsepower). If the motor was forged and the gearbox, clutch and diff upgraded would be pulling close to 600 horsepower, I guess thats the next build. Regards
Izzy