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adam87

poor mans rb25 conversion

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Poor mans rb25 conversion

 

This is for a CA18 silvia

 

Parts

Engine, loom and ecu package

Rb20/rb30 gearbox

Original starter loom and engine loom

Original oil pressure sensor

R32/c33/a31 xmember with matching engine mounts and engine brackets

OR

R33 xmember with matching engine brackets with any engine mount that is straight and 40mm in height

S13 “C” gearbox xmember

intercooler pipe work – I used mild steel mandrel bends

CA alloy/ R32/ R32gtr radiator

genuine timing belt

Genuine water pump

Genuine rear main seal

Spigot bush

dump pipe – rb dump will do or what ever suits the turbo you are using

heater hoses

thermos – 2x12” or 1x14” & 1x12”

S13 manual tailshaft

Clutch

New thrust bearing

Assorted hoses – power steering hose and radiator

 

1. start by removing all the original intercooler pipework, drain the coolant, oil, gearbox oil, undo the tailshaft from the diff and undo the tailshaft loop. Remove the tailshaft, gearbox xmember and then undo the bolts on the engine mounts, make sure to remember to take the gearstick out and remove the clutch slave cylinder from the gearbox. Then undo the engine loom from the ecu and pull the engine loom into the engine bay. Then disconnect the engine loom from the engine bay fuse boxes. Remove the radiator and it should be loose ready to pull out.

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2. pull engine out with engine crane or similar.

3. take your rb25 loom and your CA loom and send them to boot it for him to make a plug and play loom. I also believe rodeo drive does it. If any one else does I will add your name here.

4. replace engine xmember. To do this there is 2 nuts on each chassis rail that need undoing. Also need to undo the lower control arms and preferably the castor rods to make it easy. Then unclip the hard power steering lines from it. Then it should fall straight out.

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Do the steps in reverse to install the new xmember. The power steering lines will need to be bent to fit. Make sure you only bend once as they can snap if bent too much.

5. fit your timing belt and water pump and then fit your rear main seal, spigot bush, flywheel, clutch and gearbox up to the engine. Fit the oil pressure sender from your old engine in to the rb25. Bolt it all together so it’s ready to go in.

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6. make sure all accessories are attached to the engine. Ie. Alternator, starter motor, turbo.

7. using the engine crane install the engine and gearbox into the car. It WILL all go in together. Just be careful and take your time.

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8. put your “C” gearbox xmember on. Mine required one hole to be slightly enlarged. Then do all the engine mount nuts and bolts up tight. Then reattach the tailshaft and tailshaft loop. Then put attach your clutch slave cylinder to the rb gearbox. The engine is now mounted in.

gear shifter position

img0516en0.jpg

9. take your power steering pump off and install the rb25 power steering pump. The hose from the reservoir to the pump will need to be extended.

10. put your radiator in and use rb25 radiator hoses to fit up. They will need to be trimmed to fit. At this stage you can put your thermos on your radiator and wire them in.

11. attach your CA starter loom. It will need to be plugged to the gearbox 2 or 3 times (neutral switch, reverse switch and speedo sender), the alternator (same plug between the 2 engines) and the starter motor. The starter motor positive will need to be extended. Now the car should crank again.

12. make up new intercooler piping to suit your intercooler

img0559gu7.jpg

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13. attach the dump pipe and exhaust – I had a new one made because I had a different turbo but I believe an RB dump will go close to bolting to the s13 front pipe. If not it wont cost much to sort out. Attach the pipe from your turbo to afm and fasten your pod filter on.

14. this step can be done earlier also. Have a look at where your heater hoses are and where they need to go, then go to super cheap and raid the hose bins for something that will work.

15. fill engine with oil, coolant, gearbox with oil, bleed your clutch and you should be good to go.

16. put your rb25 plug and play loom on the engine, plug it all in and put it back through your firewall. Plug your ecu in and that’s it.

17. try to start it and see if it works

 

extras:

1. if your running a standard ecu, sometimes they lose a lot of torque and power in one section of the rev range. On SAU it has been noticed that by installing an adjustable exhaust cam gear and setting it to 4deg retarded this is fixed

2. if you want to use a greddy or greddy copy plenum you will need to do some modifications to some water pipes but you will also need to use an s14 or r33 clutch master cylinder

 

I in no way take responsibility for you buggering anything up.

That said if you want more photos or extra info I will try my best to get it for you.

 

I have probably forgot some things, when they come to light I will add them.

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great write up mate, much appreciated

 

what do you mean by s13 "C" gearbox xmember, is that just the stock s13 gearbox crossmember?

 

i will be doing this to a s14a very shortly, do you know if it will be the same as the s13 as far as the conversion goes? (besides wiring)

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great write up mate, much appreciated

 

what do you mean by s13 "C" gearbox xmember, is that just the stock s13 gearbox crossmember?

 

i will be doing this to a s14a very shortly, do you know if it will be the same as the s13 as far as the conversion goes? (besides wiring)

s13's have three different types of gearbox xmembers. they all have a letter stamped on them. it will be "A", "B" or "C"

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I have been told the tail shaft will need to be modified to fit?

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kudos on the write up man, just in time for my conversion

 

im putting an rb25det and box in from a r34 gtt

 

does the shifter position line up with standard?

 

is the torque loss problem solved by using an aftermarket ecu?

 

does the front xmember need to be changed? cant u just use custom mounts off the shelf for engine/tranny?

 

who else does plug & play wiring? im in vic/Melbourne any suggestions would be great.

 

 

ill post up any more info i find along the way :thumbsup:

thanks

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RB25 shifter sticks out the standard hole, and you need a little angle iron and a bit of imagination with the gearbox mount. also custom tailshaft.

 

call driftline and ask for luke about the wiring

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decent write up man, im doing this conversion atm, wat mounts did u use? im using r32 xmember but not sure wat mounts to use. i heard ford cortina 40mm mounts work? any other options? cheers

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decent write up man, im doing this conversion atm, wat mounts did u use? im using r32 xmember but not sure wat mounts to use. i heard ford cortina 40mm mounts work? any other options? cheers

i never tried the small mounts on an r32 xmember before so dont know if they would work or not. i dont think they would because of the shape... but r33 xmember and the small mounts works great.

 

for r32 xmember, rb30 mounts are cheap brand new from parts stores

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hey guys

 

just want some confirmation, if im using an A31 crossmember, and im using A31 engine mounts, should i also be using A31 RB20 block brackets?

the R33 ones that i have on the motor arent on the right angle to suit the engine mount.

 

alternatively, is there an engine mount that i can use that will make the R33 engine mount block bracket meet the A31 crossmember?

 

Will.

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heaps keen to do this conversion, only thing holding me back is the price..

does anyone have a rough estimate of how much it would cost to do a full rb25det conversion, engine, gerbox, standard turbo and parts and everything?

the more i think about it, i might just spend a little less and power up the old sr20de thats already in my s13...

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What's the difference in the 32 xmember and 33? Does one sit it further back or lower? And can u confirm shifter location to stock hole.

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What's the difference in the 32 xmember and 33? Does one sit it further back or lower? And can u confirm shifter location to stock hole.

the xmembers are a different shape completely. the r33 xmember can sit everything much lower.

shifter sits in the standard hole. it does sit a little forward.

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does any know what year the cortina 40mm mounts are off

 

need to know what mounts to use with a 33 xmember

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does any know what year the cortina 40mm mounts are off

 

need to know what mounts to use with a 33 xmember

just go to your local parts shop and look through the books for a mount that size :thumb:

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can you run the rb25 box in this combo? i give my car an extremely hard time

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can you run the rb25 box in this combo? i give my car an extremely hard time

sure can, but you need a custom (or modified stock) gearbox crossmember and the RB25 front yolk mated to the silvia tailshaft. as well as rig up a speedo

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can you run the rb25 box in this combo? i give my car an extremely hard time

sure can, but you need a custom (or modified stock) gearbox crossmember and the RB25 front yolk mated to the silvia tailshaft. as well as rig up a speedo

 

sweet as, how much would i be looking at to do this conversion? roughly.

i can do all the bolt in stuff, only thing i dont like is grafting the wiring looms, so i need someone who can do that.

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if you can do the bolt in stuff follow the guide and price up the stuff it says in the list

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if you can do the bolt in stuff follow the guide and price up the stuff it says in the list

yeah i can do that, its more the unforseen expenses that you only know about once you have done it, know what i meen? modded plenty of cars to know about them, just never done this before so i don't know what to expect. unless this is literally ALL there is too it.... seems to simple that's all.

also who is a someone who can do the wiring PROPERLY in vic?? theres no way in hell im messing with it, i i hate efi as it is, im a carby boy.

 

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i did this convertion a few years ago but sr to rb20, i didnt have to change box member or custom the tail shaft and i put a 25 box in the only thing is it looked like a little bit was hanging out at the end of the tailshaft, and i couldnt figure the speedo wiring no1 knew how to do it in my area, in the process of this time doing a sil80 ca to rb25 in the next couple of months. now i have read this and remember how to do it should be a breeze..

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any one got links on wiring, prefribly to cut and shut ca18de to rb25det looms,

done a but load of searching but the internet is broken or sum shit :P and all ive managed to find is a shit load of threads of people asking and replies of "do a search *richard cranium*"

any help would be very much apreciated

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There is a CA to RB20 one, and the RB20-25 wiring is the same:)

 

 

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can you run the rb25 box in this combo? i give my car an extremely hard time

sure can, but you need a custom (or modified stock) gearbox crossmember and the RB25 front yolk mated to the silvia tailshaft. as well as rig up a speedo

 

is it as easy as putting a rb25 yoke on the s13 uni?

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Hey guys this conversion and I can't get it to spark when I try turn it over any help would be appreciated

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