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My Rb25-30 Build

joe blo

By joe blo,
in Engines & Forced Induction

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joe blo Experienced

joe blo

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Posted (edited)

hi guys. just about to put the head on my rebuilt rb30 bottomend. still unsure of a few things so i made this thread to get the info i need.tandard computer be able to run it while i run it in coz i dont have any money to tune my aftermarket ecu and injectors anymore so hopefully i can run it in on the standard one coz i just wanna get it going. it wont run too rich and cause the rings not to bed in will it?

1. im doing a rb25 head on rb30 bottomend with rb25 headbolts and a genuine nissan headgasket. what are the torque settings and stages and tightening order and process for the headbolts?

2. what oil restrictors should i get or will the standard ones in the rb30 be ok? i have a spool rear head oil drain kit to go on it also.

3. with the power steering bit that doesnt go on properly or something does it need to be modified on the block or on the powersteering bracket? i think ive read that some of them will go straight on without modifying it, think it is the block actually. if i put up a pic can someone tell me if mine will beed to be modified? will get one later if needed.

4. what sump do i use to go into my r33 gtst? rb25 or rb30?

5. do i use all the rb25 powersteering and harmonic balancer and anything else and use new rb25 belts except the timing belt?

6. if i do the engine lowering method by slotting the engine mounts can i use the current dump pipe and exhaust and everything and it will all work properly?

7. will the gearbox and tailshaft still be aligned properly after lowering the motor?

that should do for now. been doing this for ages and always get stuck and dont worry about finishing it so i made this so i can get it done.

Edited by joe blo
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brother_david Rising Star

brother_david

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1. The ARP bolts should be tensioned to 108.5 NM, all done i three steps, i.e. 35, 80 and 108.5

-You might also want to loosen them up to 3 times before started for the first time, to get perfect tension across the head, thats what we do on our builds. Also it is recommended to do this atleast once after you have driven the car for acouple of weeks, aluminium is a living material.

2. What oilpump are you using?

3. It said to be needed to grind a small piece of the block..

4. Im using a RB30 sump, no problem with clearance!

5. Yes.

6. Probably not, the engine is 38mm taller and it wont come down that much before the sump hits the crossmember, BUT im not sure!

7. Wouldnt that be the reason for lowering the engine :D Actually, a known construction fact is that alittle angle is needed to get the correct tension on parts but its abit much if you dont change the mounts :D

Hope that helps, i might be wrong on some part but i think i've covered the morepart of it!

/Dave

Edited by brother_david
joe blo Experienced

joe blo

Posted
  • Author
Posted (edited)
1. The ARP bolts should be tensioned to 108.5 NM, all done i three steps, i.e. 35, 80 and 108.5

-You might also want to loosen them up to 3 times before started for the first time, to get perfect tension across the head, thats what we do on our builds. Also it is recommended to do this atleast once after you have driven the car for acouple of weeks, aluminium is a living material.

im using nissan headbolts. will they be the same as arp ones? or would i just tension it same as if im putting the rb25 head on a rb25 block?

2. What oilpump are you using?

il be using rb25det oil pump with crank collar fitted on crank

6. Probably not, the engine is 38mm taller and it wont come down that much before the sump hits the crossmember, BUT im not sure!

7. Wouldnt that be the reason for lowering the engine :D Actually, a known construction fact is that alittle angle is needed to get the correct tension on parts but its abit much if you dont change the mounts :D

i thought you lowered the engine so it doesnt hit the bonnet because of the extra height

Hope that helps, i might be wrong on some part but i think i've covered the morepart of it!

/Dave

Edited by joe blo
brother_david Rising Star

brother_david

Posted
Posted

1. Since its a RB25 head, and RB25 bolts and the 'weakest' part of the bolt is the nut, since the bolt has got more threads holding it down in the block, i would go for the RB25-RB25 settings.

2. Ill recommend 1.5mm front and rear, might even think of blocking the rear one, popular to do to get right oil pressure but thats more on RB26 heads that only have one oil channel to the head. Take a search in the RB30 conversion-thread, dont remember the details but its in there somewhere, just search for restrictors. Good thing you got the oil crank collar.

7. Yea sorry about that mate, ofcourse you would want to get it as low as needed to close the bonnet but still keep in mind the clearance between the sump and crossmember :D

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