First Boost Build

[DR3AMN]

Hey guys.

New here. Name is Jason (Go by Jase). Awesome forum i have been floating around reading and searching for a bit now. Very interesting stuff. Anyway i have just bought my first Boosted car its a series 2 R33 Rb25DET Manual. I have basic knowledge on N/A engines but not much when it comes to boosting.

To get to the point i have been seeing alot of benefits with going a RB30 bottom end with a 25 head for the extra torque. What i want to do is buy a RB30 bottom end and put the 25 head on there and put it in my skyline because its my daily so the extra torque would be good when not on boost.

Anyway i just have a few questions. Im new to the RB/import scene in general so please no hate or flaming me.

Is there difference between 30DET block and a N/A 30 block or is it just the internals?

What about between cars like any difference between R31 Rb30 or VL Rb30 or Old Pajero RB30 bottom ends??

Should i put my 25DET head on the 30 or a DE?

I want to keep the standard bottom end in the 30 and just put ACL race series mains and rod bearings or should i just use standard new bearings and new rings due to i am building the engine myself and just want to gain a little more experience before doing the whole forged everything incase it goes boom i wont be out of pocket to much.

Do i need to do anything to the crank when replacing the bearings like get it re surfaced? Or can i just leave it in there?

I want to use standard turbo for now at about 11 or 12psi so what would be a good CR for this without affecting off boost drivability? Goals are about 230/250rwkw

Can i use my standard 25Det ECU and loom untill i get the Haltech platinum 2000?

Im not going to put to many questions out there. While i keep looking any info would be muchly appreciated if anyone can give me any input. I havent found anyone doing something like this its all been worked motors with upgraded turbos,higher psi,lower CR for more boost etc etc.

Thanks heaps everyone. My R33 below.

[StevenCJR31]

the 30et block and 30e block are same, just different pistons, when you say pajero (mitsubishi) im sure you mean patrol

no such thing as a 30det block, all30blocks are single overhead cam

i know your keen to build your own engine but you have had to ask some VERY basic questions

you may be better off leaving it to an experienced builder

[KiwiRS4T]

Read your way through the RB30 upgrade thread at the top - quite a few non forged blocks like mine. If you are going to use the stock pistons you won't have much control over the CR but you will definitely get more torque. I don't think its worth doing it twice for the experience - build a forged bottom end and you can put all your stock head etc on top and upgrade the turbo etc at a later date. But do heaps more reading first and get to know how your present set up works before attempting to modify.

[DR3AMN]

the 30et block and 30e block are same, just different pistons, when you say pajero (mitsubishi) im sure you mean patrol

no such thing as a 30det block, all30blocks are single overhead cam

i know your keen to build your own engine but you have had to ask some VERY basic questions

you may be better off leaving it to an experienced builder

Sorry yes i mean patrol. My mistake

Yes basic question for a basic build cause im not into a full build at the moment. I want to build my own for experience. I have done a couple commodore motors but thats it the only thing that gets me is boost.

[DR3AMN]

Read your way through the RB30 upgrade thread at the top - quite a few non forged blocks like mine. If you are going to use the stock pistons you won't have much control over the CR but you will definitely get more torque. I don't think its worth doing it twice for the experience - build a forged bottom end and you can put all your stock head etc on top and upgrade the turbo etc at a later date. But do heaps more reading first and get to know how your present set up works before attempting to modify.

Oh yes that skipped my mind about using standard pistons with the CR. Yep im defiantly doing some more *studying* before attempting a build. I will be building a forged bottom end down the track but dont want to right now because i still dont know whether to build this car up or just save for a GTR.

[Duncan]

Either way a set of rb30 forged pistons + correct CR rods are a good investment.

Assembling an engine is a pretty simple case of following the instructions; the only trick is to clean everything super thoroughly (especially oil feeds). The important stuff is all done by the machine shop in getting bearing, piston and head clearances correct.

Re a 250kw target, you will not get there with a standard turbo, it runs out of puff at no more than 200kw. Engine capacity doesn't matter; the turbo just can't flow enough air efficiently. I have about 250kw from my rb30 using a ebay t3 cheapy (although I have changed to a ball bearing core).

It should still run acceptably on the standard computer, but I would not push it hard without checking it on a dyno first, you may find it strays into strange parts of the map compared to standard

[DR3AMN]

Either way a set of rb30 forged pistons + correct CR rods are a good investment.

Assembling an engine is a pretty simple case of following the instructions; the only trick is to clean everything super thoroughly (especially oil feeds). The important stuff is all done by the machine shop in getting bearing, piston and head clearances correct.

Re a 250kw target, you will not get there with a standard turbo, it runs out of puff at no more than 200kw. Engine capacity doesn't matter; the turbo just can't flow enough air efficiently. I have about 250kw from my rb30 using a ebay t3 cheapy (although I have changed to a ball bearing core).

It should still run acceptably on the standard computer, but I would not push it hard without checking it on a dyno first, you may find it strays into strange parts of the map compared to standard

Yeah im doing the assembly myself but will be sending it all off to a machinist to do the other stuff so i realised il be taking crank out anyway cause i will do those bearings aswell and get it balanced while its out. As i said the only thing that gets me is boost. Iv read that i should try get 8:5:1 or something close to that? Thought the standard RB30 rods were already strong enough??

I will defiantly be upgrading turbo as all the supporting systems down the line but for the moment i guess im just looking for a freshen up cause as i stated its my daily so will be driven alot. I was thinking today that forged pistons would be nice but what combo is best? As is turbo pistons and turbo head or N/A pistons with turbo head or N/A head with turbo pistons etc etc???

I know im making myself sound like i have no knowledge at all hahaha

[Ben C34]

Everything you are asking had been discussed before. There is a huge thread and a pdf file. It really can't get much easier, just search.

[XKLABA]

Go to eBay and search "wiseco rb", there is a package that has Wiseco piston and Manley rods

Anything from 8.5-9/1 comp ratio will work nicely

[DR3AMN]

Everything you are asking had been discussed before. There is a huge thread and a pdf file. It really can't get much easier, just search.

I have been reading that thread but its 357 pages long so its taking me a while haha Thats if you are talking about the R33 RB30 conversion thread??

Go to eBay and search "wiseco rb", there is a package that has Wiseco piston and Manley rods

Anything from 8.5-9/1 comp ratio will work nicely

Yeah i searched that i can get CP forged pistons for like $1100 (roughly) or i can get pistons and rods for like $1200 $1300 so might as well get the rod and piston kit together as 1.

How would i get that CR? Like what headgasket,pistons, and head should i use?? What CR would i get with the turbo head and standard pistons?

[XKLABA]

I payed $1100 delivered for them thanks to the exchange rate at the time, get it with the 26 pistons though as they have a lower comp height and weighs less then the others, that's what I wished I had done but already had them by the time I figured it out

get a zero deck height the measure the combustion chamber volume and work out how thick the head gasket needs to be, I think I used a 1.2mm tomei gasket with a quick shave off the head and managed to get 9.5/1 C/R

[DR3AMN]

I payed $1100 delivered for them thanks to the exchange rate at the time, get it with the 26 pistons though as they have a lower comp height and weighs less then the others, that's what I wished I had done but already had them by the time I figured it out

get a zero deck height the measure the combustion chamber volume and work out how thick the head gasket needs to be, I think I used a 1.2mm tomei gasket with a quick shave off the head and managed to get 9.5/1 C/R

Alrighty then. So what i take from this is to put 26 pistons in with 30 rods and crank?

Did you use the turbo head or N/A head for that CR and what pistons did you get turbo or N/A?

[XKLABA]

Yes exactly, which will mean you need to machine 2mm off the block to get 0 deck height which will lower head 2mm, and believe me in the 34 it would've made a difference for clearance over the motor

26 head, its in a R34 GTR, you need to CC the head to get its volume to work out comp ratio but I think the 25 has a bigger combustion camber, there is only two pistons available from wisco for RBs, 25 or 26 and the only difference is the compression height, both have 14cc dome tops

[Mick_o]

Hi Jase welcome to SAU nice 33 you've got there too

Just wondering what mods your car has currently has?

In my opinion building a 3L for 230-250kw is gunna cost decent money unless you're building the motor yourself of course. With a good tune, exhaust,intercooler & the usual supporting mods with say 3071 or 3076 or even a hypergear turbo your car will have good torque off boost and with the above mentioned turbos will achieve an easy 270kw on 98. P.S don't get a haltech

[DR3AMN]

Yes exactly, which will mean you need to machine 2mm off the block to get 0 deck height which will lower head 2mm, and believe me in the 34 it would've made a difference for clearance over the motor

26 head, its in a R34 GTR, you need to CC the head to get its volume to work out comp ratio but I think the 25 has a bigger combustion camber, there is only two pistons available from wisco for RBs, 25 or 26 and the only difference is the compression height, both have 14cc dome tops

So are you saying i should get the block machined 2mm AND the head machined whatever it needs to acheive the CR you have with say a 2mm headgasket maybe 1.5?? Or just the block?

Hi Jase welcome to SAU nice 33 you've got there too

Just wondering what mods your car has currently has?

In my opinion building a 3L for 230-250kw is gunna cost decent money unless you're building the motor yourself of course. With a good tune, exhaust,intercooler & the usual supporting mods with say 3071 or 3076 or even a hypergear turbo your car will have good torque off boost and with the above mentioned turbos will achieve an easy 270kw on 98. P.S don't get a haltech

Thank you for the welcome. Indeed its nice i love it to bits.

Yes i am building the engine myself. As mentioned above i have the experience with rebuilding engines but thats on N/A so didnt have to worry so much about CR’s, Type of pistons etc cause it was basic rebuild but i want to take it up a notch with this build.

My skyline is dead stock. Not even a FMIC and only on 5psi Why not get a haltech? Would the 25 computer be fine or should i get a 20 one and re tune it to run the 25/30?

[corey.hunter]

hi Jason,

Check out spool imports they do a rebuild kit to suit rb2530 engines, I'm currently building a motor using one of these kits for my own car, as for a computer I'd recommend something like a Apexi Power FC, they are a good computer and I haven't heard anyway really have any problems with them.

XKLABA 2mm sounds like a lot to take off the block :\ are you sure it wasn't 2thou? 2mm is 80thou, I had my block decked 2 thou to simply clean the deck up and achieve a CR of 9:1 using the JE pistons and spool rods package with a 1.3mm cometic head gasket.

[DR3AMN]

hi Jason,

Check out spool imports they do a rebuild kit to suit rb2530 engines, I'm currently building a motor using one of these kits for my own car, as for a computer I'd recommend something like a Apexi Power FC, they are a good computer and I haven't heard anyway really have any problems with them.

XKLABA 2mm sounds like a lot to take off the block :\ are you sure it wasn't 2thou? 2mm is 80thou, I had my block decked 2 thou to simply clean the deck up and achieve a CR of 9:1 using the JE pistons and spool rods package with a 1.3mm cometic head gasket.

Thanks i had a look and i might actually grab one of them kits. Id have to work out cost etc because its just a budget build while i build another fully forged 30 bottom end hence why i just wanted to re ring and new bearings to start with. Might still do it depending on CR i would get from the standard pistons from a N/A RB30 and a turbo 25 head.

[XKLABA]

Yeah 2mm 80thou, there is 3 comp height for RBs, you've got the 26 height then the 25 ones are 1.5mm 60thou higher and the 30 one are 2mm 80thou higher then the 26 ones, I've got the 25 ones and shaved .5mm 20 thou off the block to get zero deck height

This is just what I would do if I did it again, what you do is your choice, the reason I would do it way is clearance above motor on mine is that tight I had to put washers under the strut brace to clear the twin turbo pipe, plus the liter piston, from memory it's 60grams less then the 25 ones I've got now, would make a difference at 8000rpm

[DR3AMN]

Yeah 2mm 80thou, there is 3 comp height for RBs, you've got the 26 height then the 25 ones are 1.5mm 60thou higher and the 30 one are 2mm 80thou higher then the 26 ones, I've got the 25 ones and shaved .5mm 20 thou off the block to get zero deck height

This is just what I would do if I did it again, what you do is your choice, the reason I would do it way is clearance above motor on mine is that tight I had to put washers under the strut brace to clear the twin turbo pipe, plus the liter piston, from memory it's 60grams less then the 25 ones I've got now, would make a difference at 8000rpm

Ok so what if i use 30 or 25 pistons? Would i need to get the block shaved by 2mm or just 1.5mm for the 25 pistons? Or just a resurface like the head?

[Mick_o]

I know of a few people having issues with haltech computers I could also show you a video which may change your mind about them lol. Mate id suggest spending your money on ya bolt on bits 1st cos if its 100% stock you will be VERY surprised how quickly it livens up when you get it breathing. If this is your 1st turbo car take my advice and do your bolt on power mods and see if you still think you need more torque