Dropping An Rb25 Into My Silvia

[Mr. Pav]

I am doing this conversion most likely in the near future to my s15. As I have a lot of spare time I am just going to purchase the motor and clean it up and get it ready for the eventual build. I know everything I need to swap it over so I am not looking for advice on that, but one thing I was thinking of was using the 25NEO DE motor instead of the DET and turboing it.

Reasons for doing so is for the raised compression in that I could achieve great results at lower boost but this is just a theory.

Neo motor is about $2400 and the DE is around $1000

Food for thought.

I plan to just highflow the standard turbo to around the 250kw mark and nistune the standard ecu that's about it. Not sure on the factory RB injector size as I have been modifying SR's for six years and have only just made the decision for a change now.

So yeah.. this is me.. What up SAU

[Mr. Pav]

While I am at it my current setup is

SR-20DET S15

HGEAR ATR28G2 450HP .64 Turbo with standard manifold sandblasted with Tial 38mm Gate/Screamer

740cc Nismo INJ

HKS 256/264 Step 1 Camshafts

ApexiPOWERFC D-Jetro/Commander

& The general other figgily bits that we all pay hundreds of dollars for that are never going to earn back their value every again... alas

Reason for the motor swap. (oh car makes nearly 248.5kw on a "special tune" being fixed after christmas) reason for the swap of motor you might say? Well i've been getting my hands dirty on SR's for too long and I would like disrupt the weight balance in my car by unnecessarily throwing a rb25 in it XD

[PM-R33]

The Neo RB25DE is 10.1 compression, which is pretty high for decent boost on BP98 (E85 wouldn't really be a problem).

The only main differences is the Neo RB25DE block doesn't have oil squirters to cool the underside of the pistons (same as a RB30) and the block also doesn't have a turbo oil return connection.

Obviously the pistons are different with a higher crown for the higher compression.

What are you doing for the gearbox? R33 5 speed with a custom tailshaft?

Edited November 27, 2010 by PM-R33

[Mr. Pav]

depending on the funds yeah i'll just throw in a 33box phil and get hardy spicer to make me up a rb/sr tailshaft. only problem is s15 diff ratio is 3.9.1 so the gears will be too tall for the five speed.... it would be ok i guess like i said all depends on the funds. i might even use an rb20 box considering i can find one for about 300-400 dollars so there's an engine loom and box for around 2500.

then all i need is an r32 radiator/r32 engine cross member mounts and brackets/ i can use the s15 g-box crossmember and the power steering lines can be bent to fit. have to lose the viscous fan which is gay bu AU thermo fans are a great upgrade with a decent d-craig controller and the rest is as follows i guess.

[TiTAN]

the RB20 boxes arent as strong as the RB25 ones, a 250+kw RB25 will break it with some abuse.

[Dale FZ1]

The Neo RB25DE is 10.1 compression, which is pretty high for decent boost on BP98 (E85 wouldn't really be a problem).

the Neo RB25DE block doesn't have oil squirters to cool the underside of the pistons (same as a RB30) and the block also doesn't have a turbo oil return connection.

If he was prepared/able to run E85 exclusively, then agreed, 10:1 might be do-able. But I wouldn't go there with 98 pump petrol and expect to exceed his current output with the SR20 AND expect the engine to live.

The oil jets are intended to take out the thermal loading and expansion of the stock cast pistons. The extra cooling effect of alcohol fuel might negate the need for that.

One thing is for sure, high static CR and decently high boost levels can quickly lead to detonation unless fuel and ignition is right.

[PM-R33]

Yeah I wouldn't use the Neo RB25DE. God knows when we will get E85 in Townsville and even though you could run low boost with BP98, you will never have any head room later on.

Not to mention if you ever got a decent boost spike it would easily kill the engine.

Also as mentioned, definetely don't go the RB20 box. You might save a bit of coin initially, but once you blow the gearbox it will end up costing you more in the long run.

Personally I think the costs involved to do it right are quite high and you aren't gaining a huge amount compared to what you have.

RB25DET or RB25DET Neo: $2000-$2500 (let's say it comes with an ECU and loom)

R33 Gearbox: $1000-$1500

Nismo injectors: $700-$1000

Z32 AFM: $200-$300

Clutch: $500-$1000

Nistune: $400

Tuning: $300-$600

Hypergear turbo: $1250-$1500

Custom dump pipe: $200-$300

Custom intercooler piping and silicone: $200-$500

Splitfire coilpacks: $600-$800

TOTAL: $7,350-$10,400

You allready have an in tank fuel pump, boost controller and a couple of other thing so I didn't include those. But the list still doesn't include costs for the cross member, radiator, custom tailshaft, engine mounts, thermo fans and not to mention all the other costs that come with such a big project. You also mentioned to me earlier that you wanted to freshen up the RB25 before putting it in, so there's the cost of a water pump, timing belt, seals, idler pulley, tensioner, gearbox oil, engine oil, filters etc. Also the list includes no labour but i'll assume Alex will be helping to do most of the big work.

Depending on what parts you can get second hand I still think it is an easy $10,000 job to do correctly.

So for $10,000 you get the same power as your SR20 with just more power through the rev range due to the extra displacament of the RB25, however you still have a stock RB25 with a highflow.

You also lose the big advantage of the nimble S15 handling by adding 70-90kg to the front of the car and pushing the weight a lot more towards the nose. Most people you read about doing it say it is a very noticable difference, including Trent:

rb into s series equals handling shite..... no matter your budget.... the SR will always handle better.

Personally I think I would rather spend $10,000 on the S15 and the SR20.

My 2C Pav.

Edited November 28, 2010 by PM-R33

[STATUS]

depending on the funds yeah i'll just throw in a 33box phil and get hardy spicer to make me up a rb/sr tailshaft. only problem is s15 diff ratio is 3.9.1 so the gears will be too tall for the five speed.... it would be ok i guess like i said all depends on the funds. i might even use an rb20 box considering i can find one for about 300-400 dollars so there's an engine loom and box for around 2500.

then all i need is an r32 radiator/r32 engine cross member mounts and brackets/ i can use the s15 g-box crossmember and the power steering lines can be bent to fit. have to lose the viscous fan which is gay bu AU thermo fans are a great upgrade with a decent d-craig controller and the rest is as follows i guess.

s15 diff ratio is around 3.69.

the neo DE engine is good only for E85 forget 98ulp

Use r33 xmember and mounts the lot will bolt in.

having done lots of rb conversions into S series including our 400rwkw rb26 in s13.... forget it. build the sr it will handle better and with e85 will make decent power and torque.

@ the moment my favorite customer car is a built SR with a simple gt-rs on e85 280rwkw 22psi and it is on boost in a blink and pulls all the way to a low limiter of 7200rpm... absolute weapon.

[PM-R33]

@ the moment my favorite customer car is a built SR with a simple gt-rs on e85 280rwkw 22psi and it is on boost in a blink and pulls all the way to a low limiter of 7200rpm... absolute weapon.

Agreed.

My mate had (just sold it) the nicest S15 in Townsville by far (XCITE U). Had a GT-RS package making 240-250rwkw with some HKS cams and was the best S15 I'd driven by far.

[STATUS]

Agreed.

My mate had (just sold it) the nicest S15 in Townsville by far (XCITE U). Had a GT-RS package making 240-250rwkw with some HKS cams and was the best S15 I'd driven by far.

ex autobarn guy?

[PM-R33]

Haha yeah George. I forgot you knew George, Dan and all them from back in the day

[Mr. Pav]

well im fairly sure the 33 cross member sits the gearbox up way to high.

all the pipeing including I/C pipeing and front pipe down pipe will be done for free... anton is THE SHIT at welding now

i have a z32 i can get for practically nothing.. eccys cheap uleh

i reckon if i can drive noble enough to keep my six speed in the s15 alive at the power figure an rb20 would probably hold up if i looked after it

i am going to tune it myself

i am hopeing to hunt around for the 32 bits i need for absoluetely nothing considering the amount of junked up ones there are lieing around townsville and the connections we have phil

like i said.. im getting the actual motor it self and just prepping it for something to do and getting it all ready... if i get it on a good price worst case scenario is i can sell it and make my money back if i don't put it in...

in saying so this is in the near future as a possibility over re-building the SR if i pop it.

what power can the stock six set of 33 injectors handle anyway phil

[PM-R33]

Dependent from engine to engine.

On standard rail pressure you will start seeing above 95% duty cycle at around 210-220rwkw

[Mr. Pav]

oh and i meant to say the standard crossmember sits the engine up to high. most people end up smacking in their bonnet using the 33 one.

could always just buy a reg and bump up the pressure..

[robbo_rb180]

rb25 in s chasis is fun. the low down torque is great even with a standard motor.

i haven't got any problems with how my car handles.

i got 230kw from my standard injectors & had no problems.

the only problem i had for a while is that the water temp would go to 90-95 on a hot day up here. i put in a nismo thermostat and that fixed the problem.

if u want i have a rb20 box & g/box x-member & tailshaft left over from when i upgraded. the rb20 box was good and i had 230kw & a shagged clutch

i also have a 32 gtr radiator thats been reco'd if your interested.

if i had the time and there was a dedicated track up here. i would put a rb in my other 180 as well, since i pretty much have everything needed

[Rolls]

Ive run an rb20 box with a 25 with 240kw and semi slicks, provided you granny shift it it should last fine, mine isn't making any weird noises yet.

Sounds like it will be a very nice setup though

also whilst you are making the weight distribution worse, is it really that much worse? does having a much nicer motor offset the difference in 'fun' the car is? It isn't like he is making a time attack car.

[STATUS]

rb25 in s chasis is fun. the low down torque is great even with a standard motor.

i haven't got any problems with how my car handles.

i got 230kw from my standard injectors & had no problems.

the only problem i had for a while is that the water temp would go to 90-95 on a hot day up here. i put in a nismo thermostat and that fixed the problem.

if u want i have a rb20 box & g/box x-member & tailshaft left over from when i upgraded. the rb20 box was good and i had 230kw & a shagged clutch

i also have a 32 gtr radiator thats been reco'd if your interested.

if i had the time and there was a dedicated track up here. i would put a rb in my other 180 as well, since i pretty much have everything needed

yeah but some bodys "happy" with handling is another nightmare (you obviously have never been in a good handling car). SR vs RB in the handling stake is a no brainer.. the rb just sits far too forward of the front axle centre line to handle anywhere near as good as a SR. We moved the RB26 back and it still wasnt enough to match the sr (cornering g wise) ... you need to come back around 20cms which just aint provided for.

[PM-R33]

Yeah I believe the Tein S15 with a RB in it modified the shit out of the firewall/crossmember/engine mounts etc to try and get the RB to sit as far back as possible.

[STATUS]

Yeah I believe the Tein S15 with a RB in it modified the shit out of the firewall/crossmember/engine mounts etc to try and get the RB to sit as far back as possible.

27.5cm backwards

[Dan_J]

ment to be running 10kg front spring rate if you do run the rb25, its said to be a lot better over the 8kg fronts due to the extra weight

Edited December 2, 2010 by Dan_J