Building A Forged Rb25

[75coupe]

Tomei is the same part as ARP? Who's leg are you trying to pull now?

You have a habit of pretending to know what you are talking about but in reality you have no idea. Leave the expert comments to the guys who actually have the expertise. Tomei run a widened step in the shank and use 6 point nuts where ARP run a parallel shank and use 12 point nuts. They also do not share common base material and are formed using different manufacturing process.

I guess the statement was in relation to the OPs want of a daily driver with no huge HP requirements and only wanting to rev to 5K rpm...?

Heaps of people running arp by the sounds of it on here with alot more serous engine builds than this thread is sounding like...

[zebra]

Tomei is the same part as ARP? Who's leg are you trying to pull now?

You have a habit of pretending to know what you are talking about but in reality you have no idea. Leave the expert comments to the guys who actually have the expertise. Tomei run a widened step in the shank and use 6 point nuts where ARP run a parallel shank and use 12 point nuts. They also do not share common base material and are formed using different manufacturing process.

Lol calm down son

[N1GTR]

Tomei is the same part as ARP? Who's leg are you trying to pull now?

You have a habit of pretending to know what you are talking about but in reality you have no idea. Leave the expert comments to the guys who actually have the expertise. Tomei run a widened step in the shank and use 6 point nuts where ARP run a parallel shank and use 12 point nuts. They also do not share common base material and are formed using different manufacturing process.

Well no points for guessing who you've been listening to.

As 75coupe was smart enough to realise, I'm not claiming (as you have assumed) that arp sell bolts to tomei and tomei resell them. I was simply trying to say that an upgraded bolt is an upgraded bolt. Arp bolts do well in a wide range of cars (including your friends one), so why spend more money than is required when the owner wants to ditch the factory bolts (your friend will also tell you that's an unrequired upgrade as way more than his target power level can be achieved on stock bolts) when that money can be spent elsewhere like going towards a tune for example, or even spent on something completely unrelated to cars.

[N1GTR]

I guess the statement was in relation to the OPs want of a daily driver with no huge HP requirements and only wanting to rev to 5K rpm...?

Heaps of people running arp by the sounds of it on here with alot more serous engine builds than this thread is sounding like...

Agreed.

[XxNinjaxX]

ok well i got my engine bits today so ive got

1.Bare block (honed, standard bore)

2.Fully machined head

3.Crankshaft

4.Couple boxes of unlabled bolts

where should i start? i figure get the bottom end together firstly, i inspected the pump drive on the crankshaft and can clearly see that it needs the collar as its showing signs of wear and tear on the driving edges so im thinking get it acid dipped, get one put on and have the crankshaft fully reballanced as a first step.

i can use as much help with this as i can get so load me up with info guys!

[DR 32R]

What are you doing for main bearings?

[marksuxass]

First thing id be doing is measuring it all again, just to be sure it is all standard. Was there a reason why this engine was stripped down for a build? Its gonna be hard to do it at our workshop, cause we dont have any bore gauges/dial gauges. I just used an inside micrometer to give a rough measurement on my bores, plus my pistons where standard size when i pulled them out of the engine. Its going the next size oversize anyway (86.5mm) so i should have plenty of room to play. Id also get it x rayed just to be safe cause they usually crack around where the head blots go through the block along to the water jacket. But yeah just basically re measure everything again. Then start ordering parts/do more machining if need be.....

[Rolls]

If its not burning oil and puffing smoke and the bearings don't make any noise don't touch it, just lean on it until it explodes, then build a motor, no point taking apart a working motor for small power goals like you are aiming for.

Just get a highflow turbo (loads of power down low if you get the right one) and you'll make oodles of power under 5k, stock motor will take it fine as anything above 300kw will mean the power is being made from 5-7 not 3-5 like you want.

[SoFreshSoClean]

+1 for GT-RS

On the street there is honestly no need to rev an RB25 with this turbo very high, having full boost by 3k rpm means any overtaking you wanna do is easy. Its actually worrying how quickly they gain speed if you dont keep an eye on the speedo.

(But if you wanna rev to 7k every now and then they still have some punch )

[XxNinjaxX]

First thing id be doing is measuring it all again, just to be sure it is all standard. Was there a reason why this engine was stripped down for a build? Its gonna be hard to do it at our workshop, cause we dont have any bore gauges/dial gauges. I just used an inside micrometer to give a rough measurement on my bores, plus my pistons where standard size when i pulled them out of the engine. Its going the next size oversize anyway (86.5mm) so i should have plenty of room to play. Id also get it x rayed just to be safe cause they usually crack around where the head blots go through the block along to the water jacket. But yeah just basically re measure everything again. Then start ordering parts/do more machining if need be.....

today i measured the top of the bores with the big verniers and all read around high 86.00 to 86.05 across all cylinders, i know this is a crude way to measure but its best i could do with the available tools so im pretty sure its on its first build. got told it was a running motor stripped down at 122,xxx so the head could be used on a 25/30 build then i guess he decided to rebuild it again with a different head? appears to be in good condition though, big ends were intact, no scoring on the crank but i did notice some heat discoloration around where the oil pump drive is, not sure if this is common though. the core plugs have been removed to inspect the water passages, no corrosion is present. going to get the block acid dipped just to be 100% though. also sticking with the hydraulic lifters and just running type-b poncams so i'll definatly be getting them serviced before they get refitted.

[NYTSKY]

Type B Poncams are for NEO heads.

If the head has the metal CAS you need the Poncams for a series 1. Part number ending in 020.

[R31Nismoid]

my aim is anywhere from 300>350hp atw safely and without having to worry about the motor breaking while im giving it a bit of stick on the odd occasion

So its 220rwkw-260rwkw - factory motor is MORE than adequate for that.

There is no reliability problem at all with that power level.

Your part list is long, expensive and overall pointless for that power goal.

[marksuxass]

today i measured the top of the bores with the big verniers and all read around high 86.00 to 86.05 across all cylinders, i know this is a crude way to measure but its best i could do with the available tools so im pretty sure its on its first build. got told it was a running motor stripped down at 122,xxx so the head could be used on a 25/30 build then i guess he decided to rebuild it again with a different head? appears to be in good condition though, big ends were intact, no scoring on the crank but i did notice some heat discoloration around where the oil pump drive is, not sure if this is common though. the core plugs have been removed to inspect the water passages, no corrosion is present. going to get the block acid dipped just to be 100% though. also sticking with the hydraulic lifters and just running type-b poncams so i'll definatly be getting them serviced before they get refitted.

Yeah refer to the service manual for doin the proper measurements, you could have wear along the thrust faces of the bores, and because its been re honed you wont really be able to see the wear until you measure. Measuring these are crucial before you put anyting back together. Few simple steps to insure you dont build a motor that smokes its head off, and piston slaps every time whilst its cold.

[DR 32R]

So its 220rwkw-260rwkw - factory motor is MORE than adequate for that.

There is no reliability problem at all with that power level.

Your part list is long, expensive and overall pointless for that power goal.

Well you could add all the mad fun forged bits porting and cams, just move your power and revs goal up!

[XxNinjaxX]

Type B Poncams are for NEO heads.

If the head has the metal CAS you need the Poncams for a series 1. Part number ending in 020.

good call, meant to type, type-A

im actually considering not forging the motor due to pure cost factor (looking at 4>5k and thats not including a turbo kit) still would run uprated bearings, headstuds, main studs, cams etc.. if i tune it to around 300hp atw on standard rods and pistons would the motor still be reliable or should i just save and forge it anyway to be on the safe side?

[Rolls]

why do you even need a rebuild? building a forged motor when you dont need it is silly, you get piston slap with forged pistons which wears the bores faster, just leave it stock and put a highflow on it, when it finally shits it self consider the rebuild then.

the motor will be reliable complete standard, they are reliable from the factory, why do you need to pull it all apart?

Edited November 7, 2010 by Rolls

[XxNinjaxX]

why do you even need a rebuild? building a forged motor when you dont need it is silly, you get piston slap with forged pistons which wears the bores faster, just leave it stock and put a highflow on it, when it finally shits it self consider the rebuild then.

the motor will be reliable complete standard, they are reliable from the factory, why do you need to pull it all apart?

im building a backup motor, its a diffrent one than the one in my car now. my current engine has piston slap when cold so this is why ive decided to build a replacment engine before my one shits its self all together and i have no engine at all

[zebra]

good call, meant to type, type-A

im actually considering not forging the motor due to pure cost factor (looking at 4>5k and thats not including a turbo kit) still would run uprated bearings, headstuds, main studs, cams etc.. if i tune it to around 300hp atw on standard rods and pistons would the motor still be reliable or should i just save and forge it anyway to be on the safe side?

Ill say again, there is no need for ARP/TOmei studs on a stock motor, hell even a 600hp RB will be fine with new standard stuff.

You will go backwards using bigger cams with a stock or small turbo, any gain you make a 6000rpm you WILL lose down low, you keep saying that you want power up until 5000rpm...so why do you want big cams?

[Rolls]

im building a backup motor, its a diffrent one than the one in my car now. my current engine has piston slap when cold so this is why ive decided to build a replacment engine before my one shits its self all together and i have no engine at all

so just buy a spare stock motor, it will cost almost 5x less and will meet your demands.

[zebra]

so just buy a spare stock motor, it will cost almost 5x less and will meet your demands.

YUP!!!!!