Setup proposal... RB25DET...

[Dramier]

Ok, I've done my research and homework in figuring out what I want to run, and I wanted to run the list by you guys and see if there were any potentional holes that I might want to change or patch up...

Goal: ~400 to 500HP.

Already done: RB25DET. Greddy S14 FMIC.

The list:

Turbo: GT35/40R *new*Injectors: Nismo 650 or 740cc...FM: Apexi PowerFC + Comm.Wastegate: Tial 35mm externalAFM: Z32Clutch: Exedy Hypersingle. (got one in the S2000, works awesome)Fuel: Inline 255lph pump. (HKS or Walboro)Fuel2: HKS adj. regulator.

Now.. All of these parts with the exception of the AFM I will buy new and have already sourced, but if I'm steering wrong here anywhere or there's something I haven't thought of or left out, please feel free to tell me.

Basically I've put togethor my list based off of SDU's cars and a few cars in the U.S. that are putting down the same numbers I'd like to see. I've also thought seriously about pulling the motor and doing all of the top-end with new goodies, but based on what I have researched about the RB25 it's not really necessary. But anyway, opinions welcome.

[eh?]

Nothing wrong with any of that except you could have gotten some lower priced parts.

Anyway..buy my power fc

[rbsileighty]

Don't forget a piston set... and a radiator might not be a bad addition either

What are the specs on that "GT35/40R" and I can tell you if it's right.

[T4 RB25det]

pistons should be fine for now, mine are holding up nicely, even when you consider they are the DE pistons. also still on stock radiator. but i am replacing the rad here soon.

setup looks pretty similar to mine right now tho

[rbsileighty]

There is a difference between "can" and "should"...

What are your driving temps looking like at that power level and stock rad?

[T4 RB25det]

normal driving temps are just like they were when it was all stock, i dont beat on the car for long periods of time, so they dont really get very high ever.there are many 400+whp rb25s on stock block

[rbsileighty]

He included 500 hp... which I assume means at the wheels... and from what I can recall 2 of the 25's on these boards have broken due to pistons at that power level.

Good point on the load issue with the rad. I've been thinking about this one a lot and would like to limit the amount of fluid I add to the front of my car (+water=+weight). I guess as extended road coarse use was on the agenda then stock radiator should be fine for a while.

[Dramier]

Honestly, I don't care whether it's 500 at the wheels or the crank.. it's just kind of what I have learned is the "safety" point. Should be safe to crank off a dyno run and maybe a track run, then after that turn it down and enjoy...

Currently I'm using an new OEM Z31 radiator with electric fan, and the car hardly ever gets warm. Most of the time the fan doesn't even cut on. Temps are pretty low and I tend to dog it quite a bit on the weekends.

I'm choosing the big names because I can get them from one place and since it's overseas, might as well combine orders and save some money on shipping. It's not that expensive really, but if some of you have other suggestions that are less expensive but just as good, I would appreciate a link to what and where.

I chose the GT35/40R series turbos because of their popularity overseas with the RB crowd and the relative ease of finding them in the states. As far as pistons go, I could do that, but if I'm going that far I'll need specs on the engine that I don't have at this time. Having no internet at home (I'm at college) makes it hard to find information sometimes.

I've thought about pistons, but if I'm going to do that, I might as well go with the whole top-end and that's not cheap. For what I plan on doing (kicking local asses occasionally but mostly daily driving) I don't think I really need much more than 400HP and stock internals..

Thanks for the replies so far..

[T4 RB25det]

really, the weight difference shouldnt turn you away from putting a new radiator in, the only reason i havnt put mine in is because when im not at class, i am working, and when im not working or at class im sleeping or doing homework. When you add 150lbs more up front to your car the 8lbs per gallon for coolant will be a very nominal change in weight distribution. most aftermarket radiators can only hold about 1 liter more than stock, and the aftermarket ones are lighter to begin with.

I kinda use ym car as a daily driver since i hate my beater car, and it has given me no problems overheating in traffic. although i have 2 pusher fans on at all times.

if you are going to upgrade pistons, you could simply buy an RB30 block from aussieland and ship it over for a total of around $500. rb30 blocks go for 3-$400. and then proceed with your build. that way for $500 more you just gained .5 liters of displacement and the rb25 head fits right on with no modifications.

One thing you might want to think about getting would be a set of cams. Its going to be kinda hard to get 400hp out of stock cams.

[rbsileighty]

Point taken on the rad... I will have to agree regarldless of the fact my 20 couldn't weigh 150lbs more than the KA... even with the front mount. This is going by the some people who have weighed their S-cars after the 20 swap. I try to pinch pounds... but I guess some shouldn't be pinched. It is good to safeguard... which is my logic behind the pistons on a 500hp 25 motor.

I would advise against the 30 idea though... the added height is not your friend in the S-chassis. I guess go at it with the 25 without pistons and drive it till you pop it... which may or may not happen. One way to find out.


Modified by rbsileighty at 2:52 PM 10/13/2005

[Dramier]

really, the weight difference shouldnt turn you away from putting a new radiator in...

I've got a 300ZX with an RB25, not a 240SX. My radiator is substantially larger than a 240's stock rad. (If you were referring to me that is.. if not, sorry, ignore..)

if you are going to upgrade pistons, you could simply buy an RB30 block from aussieland and ship it over for a total of around $500. rb30 blocks go for 3-$400. and then proceed with your build. that way for $500 more you just gained .5 liters of displacement and the rb25 head fits right on with no modifications.

An RB30 block would be awesome, but since an RB25 barely fits I really don't think an RB30 will squeeze in at all. Besides that, I have no desire to pull the engine at this point in time and go that route, but I will definitely keep that in mind and maybe do it while I'm playing with the RB25. Where are some reputable shippers for shortblocks? I'm guessing you will need basically everything except the head for the RB30... ?

One thing you might want to think about getting would be a set of cams. Its going to be kinda hard to get 400hp out of stock cams.

Yes, I had forgotten about the cams. I haven't done my research on what type to use and what lift/duration/etc. I'm open to suggestions there but I haven't searched yet so forgive me for my ignorance. Along those lines, might as well throw in a pair of adjustable cam gears I'm guessing... ?

[eh?]

He included 500 hp... which I assume means at the wheels... and from what I can recall 2 of the 25's on these boards have broken due to pistons at that power level.

Fito broke his because he used pump gas with a race fuel map and he was making closer to 600rwhp. Who's the other guy?

[wawazat8402]

I wont be scared to push mine to 500whp on stock pistons. The key is tuning.

[rbsileighty]

Fito broke his because he used pump gas with a race fuel map and he was making closer to 600rwhp. Who's the other guy?

Honestly, the only one I can think of is Fito's off the top of my head... can't remember who the other one is I was thinking of...

Didn't remember it being due to running the wrong map... Sounds like you know what you're talking about, and excuse me for putting my nose in where it doesn't belong.

[T4 RB25det]

for cams if you want good top end power a 272 cam would work pretty good. cam gears should go along with that also, but not aboslutly needed. I am using stock cam gears with hks 272's

the RB30 block is the same length as the rb25 but has a higher deck hight. not by too much. The 300zx has a deeper engine bay than a 240 anyway so at most if you wanted to run an rb30 you would need to notch some hood webbing. This swap is very uncommon in the states right now, but since its pretty cheap its going to become more and more popular soon. You would need the block and crank. get aftermarket pistons and i think rb25/26 rods fit. dont quote me im not sure.

what exhaust manifold are you going to be running? the stock unit will cause a great deal of lag because of its restrive design. What about intake manifold?

[rbsileighty]

I wont be scared to push mine to 500whp on stock pistons. The key is tuning.

Well... I was thinking about it some more and I'm still not convenced. So is this on pump fuel or leaded? With consistant pump fuel and daily weather that is the same as the day you tuned... ok... but unless you are tuning with each tank and every day... I'm not convenced they will last a long time at 500hp. I would be scared/uncomfortable pushing my 25 (if I had one) with 500hp even on a good tune. To many factors can go wrong... even with a "good tune."

[Dramier]

for cams if you want good top end power a 272 cam would work pretty good. cam gears should go along with that also, but not aboslutly needed. I am using stock cam gears with hks 272's

Can you be a bit more specific than "good top end power"? Like what RPM range are we talking here..? I'm a bigger fan of a typical V8 style powerband of say... 2500-4000 max rather than a high-revving powerband like my S2000 has.. What are the 272's power band? Also, the adjustable cam gears are meant to adjust the timing, correct? If so, aren't they pointless with a standalone ECU like the PowerFC?

the RB30 block is the same length as the rb25 but has a higher deck hight. not by too much. The 300zx has a deeper engine bay than a 240 anyway so at most if you wanted to run an rb30 you would need to notch some hood webbing. This swap is very uncommon in the states right now, but since its pretty cheap its going to become more and more popular soon. You would need the block and crank. get aftermarket pistons and i think rb25/26 rods fit. dont quote me im not sure.

The engine bay IS deeper, however, there's a crossmember in the way.. heh..

what exhaust manifold are you going to be running? the stock unit will cause a great deal of lag because of its restrive design. What about intake manifold?

Exhaust manifold I was looking at an SSAutochrome or an OBX unit, but after reading a few "disaster" threads about them.. I'm kinda sitting here wondering what to do... according to this forum, nothing bolts up to the stock manifold so I'm not really sure what I'm going to run for a manifold yet. I may just eat the cost and get an HKS or Greddy unit unless somebody has a better suggestion. The intake manifold I'm going to attempt to squeeze one of the Greddy units in if it will fit and I can find one, if not, I will just have to make my own.. Basically the manifolds will kind of be determined by the turbo I pick.. which will be based on price and condition.. Definitely a 70mm with a small A/R trim for faster spool, that's what I like based on other cars I've driven/ridden in.

Also, does the external wastegate even matter at all with the PowerFC? I'm under the impression you control boost electronically via the FC and the wastegate is really nothing more than a backup system in case of controller failure... correct or am I smoking a rock?
Modified by Dramier at 2:26 AM 10/16/2005

[rbsileighty]

I can run the numbers on where your power band will be if you run a 272 if you can get me the runner diameter/length of your intake mani and the volume of the plenum... it will be in your upper range for sure though... which is one reason for running a higher duration camshaft (just remember the hp equation ((tq*RPM)/5252))...

I have the same reasoning you do on the RB30 idea...

Must be good rock... just messin... but a electronic boost controller controls when your wastegate opens... so you still need one.

[Dramier]

Heh... cool...

I've just got a stock RB25 plenum and manifold right now, but I can't give you an idea of what they will be until I figure out what I'm going to use in it.

Not having done a search yet, what is the general opinion of turbocalculator's stainless steel T3 turbo manifolds? I've already seen not to go SSAuto or OBX...

By the way, what does the PowerFC -NOT- do for you? (In other words, what other electronics are required, if any?)

[T4 RB25det]

for an rb25 you are not going to find really good low end power and still have massive top end around 500 or so. In order to hit 500 you will need either a huge t3 flanged turbo or a moderately sized t4. Everything you do pretty much is going to increase turbo lag with the exception of new exhaust manifold. The new intake manifold is going to create more lag, but provide more power up top, bigger turbo...well same thing. cams will create more lag, but not all that much. i could bearly notice from coing from stock cams to hks 272s.The cam gears will affect cam timing not ignition timing. the power FC will control ignition timing. changing cam timing cam dial out overlap and can reduce spool time if done right.The cams will be a good idia, since its not going to be easy to hit 500 on stock cams. When i say 272 i mean the duration of the cam. HKS, APEX, tomei, and maybe greddy? all make cams for RB motors, take your pick.

As far as manifolds go i use the phase 2 motorsports one. it was the only moderatly priced manifold i could find that wasnt crap. A few problems were that the turbo hit the valve cover so i had to cut it and re-weld it so it would fit. Doesnt mean it will happen to everyone, i am running a rather large turbo.the turbocalculator manifold is the ss autochrome

[wawazat8402]

Well... I was thinking about it some more and I'm still not convenced. So is this on pump fuel or leaded? With consistant pump fuel and daily weather that is the same as the day you tuned... ok... but unless you are tuning with each tank and every day... I'm not convenced they will last a long time at 500hp. I would be scared/uncomfortable pushing my 25 (if I had one) with 500hp even on a good tune. To many factors can go wrong... even with a "good tune."

not on pump gas, there is a station a couple miles from my house with 110. also i have seen the local tuner that will tune this engine push other engines beyond what people have thought was safe. he is also very straightforward if he believes i may be pushing the engine too far. it should also be noted that my RB25 is not daily driven. It is only a weekend car for me, so the fear of it popping is not near as strong as it would be if it were my only transportation.

[Dramier]

for an rb25 you are not going to find really good low end power and still have massive top end around 500 or so. In order to hit 500 you will need either a huge t3 flanged turbo or a moderately sized t4. Everything you do pretty much is going to increase turbo lag with the exception of new exhaust manifold.

Top-end power is basically useless in the U.S. unless you live next to a high-speed ring. I'm guessing by top-end you mean 140+ mph and not top-end as in 5k RPM plus?

As far as manifolds go i use the phase 2 motorsports one. it was the only moderatly priced manifold i could find that wasnt crap. A few problems were that the turbo hit the valve cover so i had to cut it and re-weld it so it would fit. Doesnt mean it will happen to everyone, i am running a rather large turbo.the turbocalculator manifold is the ss autochrome

Ok.. if the turbocalculator manifold is the SS Autochrome manifold, why are there two different sites for it and two drastically different prices??? Kinda weird.. Who makes the 'Phase 2 Motorsports' manifold and where can it be found? I didn't find it on a google search nor in the NICO forums anywhere..

In fact, there's only a few places I know of that sell RB25 performance parts new, and the main one I'm looking at is Greenline. If there are other places, it would be nice to see them in the sticky threads somewhere..

[T4 RB25det]

there are many different sites that sell the same manifold for differenct prices.phase 2 manifold http://www.store.yahoo.com/pha....html

by top end i mean rpm, not speed. you wont have good throttle response with a 500whp 2.5 liter

[Dramier]

there are many different sites that sell the same manifold for differenct prices.phase 2 manifold http://www.store.yahoo.com/pha....html

by top end i mean rpm, not speed. you wont have good throttle response with a 500whp 2.5 liter

Oh ok, I didn't realize you were referring to RPM for top-end. I expect to do a dyno run, and probably downgrade the turbo after that to get better spool.. but honestly I'm just going to give it a try first and see if I like it, and if I don't, then I'll deal with it from there. It's better IMO to go up and not like it than shoot too low and have to go up.

$1k for that manifold is pricey... Is there any reason the manifolds are so much more expensive? The engine isn't -THAT- rare anymore.. Hell, even Summit is starting to carry SR/RB parts!