SKiT_R31

Hey All, Just after these cheap, so i can bolt a head and block together to do a leakdown/compression test. Cheers, -Dan

As above for the stock air ratio. The optimum A/F ratio for N/A applications is 12.5:1 for best power when rich, and 13.2:1 for best power lean, so somewhere around there (If your intention is to tune it with an SAFC or something for better power or economy). WOT enrichment is generally to protect the engine/engine components like spark plugs. If you were to run a cooler plug, good fuel with appropriate ignition timing, you really shouldn’t need as much enrichment, will get more power and better economy. Sometimes when maintaining WOT at high RPM on leaner fuel mixtures, components such as pistons can continually absorb extra heat (while the head and block are cooled sufficiently), that’s when you use fuel to cool them. Generally you'd use somewhere at the lean end of the best power for part throttle, and somewhere around the rich end for at WOT, it really depends how high strung your engine is (compression/ignition timing/revs) and how hard it’s driven.

Your all negative nancy's. I'd be aiming to make peak power at about 8000rpm, you want the most rediculous cams you can find, adjustible gears for fine tuning power, matched length inlet runners (doesnt have to be ITB's, at the cost of responce you could get a better tune with a large single) and exhaust pipes (for that RPM) decent headwork and oversized std valves (not titanium), lightweight pistons, aim for a compression ratio in the mid 12's, but do it properly (with the pistons coming out past the deck, as far as the thickness of the headgasket) then get really good management and get a good tuner to tune it properly. You want the tuner to monitor EGT's, to run the optimal fuel mixture (between 12.5-13.2) and the maximum ignition timing without creating too much heat or causing detonation. General lightweight gear (flywheel to wheels) and 4.4 diff gears, it wont be slow, easy >200hp then just ring its neck. It doesnt take rediculous amounts of power to go fast, it really depends what its for. If you get all the supporting mods sorted (oil pump, lifters, balencing - from balancer to clutch and everything in between) it will be a beast, and the power it makes could suprise you, providing you do your math right and ensure everything is 100% matched for a peak torque and power at the same spot. You need to talk to a really good professional engine builder, dont go to an RB specialist, go to somone who can get 200hp out of an oldschool pinto, and they'll work wonders .

You should put some pics up

I love magnaflow mufflers, look and sound. Oval straight through centre offset, they're a mandrel preforated pipe that are fibreglass packed and use absorption to reduce noise, and that type of muffler (straight through) gives the best performance (minimal backpressure). I've got a satin stainless one at the rear, and the biggest (longest) hotdog resonater i can find before the diff. It's a 3" system on my RB30DE, sounds unreal, you'd obviously be after a 2.5" though. http://www.magnaflow.com/02product/univers....asp?shape=oval http://www.magnaflow.com/02product/shopexd...ain&id=8517 My car is quite loud (however its slightly different to a standard rb25de) but has absolutely no drone, it just rumbles down low and screams with revs. I'll change the hotdog to a centre/center straight through at somepoint, just to quieten it down so its more street drivable (when i want to street drive it, down the track).

When my R33 GTS4 was N/A it got beten by a Gen1 Liberty GX to about 80

I'm sorry to go against the grain, but I would skip the port and polish, the ports are easily large enough for the 2.5L, any boring or polishing (esp without the intake manifold matched) will be negligible. so many people incorporate it in builds (which is fair enough in a full high power build), but as a single modification I see so many dyno at a power level (lets say 110kW) spend $1g on a 3way P&P and end up with 112kW, I think the money is much better spent elsewhere first, then do the P&P once its the next most efficient power per dollar mod. To make that power, I would aim for revs and compression. You can regrind your cams for around $500 to what I have in my RB30DE (which made >200hp, but of course 3L) which are surecam 8.3/255's (and you can keep VCT, maybe change the swap over though). Or you could spend the money saved on headwork on some aftermarkets, there are basic 8.5/256's for <$900, I'm not sure how much lift you can have before needing to machine the buckets, maybe around 9? Next is compression, compression makes power, but too much ruins drivability from needing to use better fuel or having to reduce timing etc, If you were to bump it up from 10:1 to ~ 11:1 and then get it tuned, i think that would make a nice improvement. You sort of need to research yourself, but these need to all be done at once, you should match your cams with your intake manifold and your exhaust manifold. You can find calculators on the net which you enter your engine specs (bore/stroke/cam profile/valve sizes etc) and where you want your peak torque (the higher your torque peak the more peak power you will have) if you can then find (off the shelf front facing) or make a manifold to suit, with the cams and adj cam gears you can match these, to push your power up higher in the revs (which translates to you making more power) if all this is done correctly, the power shouldn’t be too hard to make. People tend to struggle when they just throw random parts together which aren’t matched. So yeah, in summary, in my opinion, get meaty cams, and increase your compression then tune it, this can definitely get you your power, but to maintain drivability you may limit yourself to less compression/milder cams, to which you should increase efficiency's elsewhere (like correctly matched intake manifold, tb(s) and intake piping). With cams, you may also want to look into a larger throttle body (easy with a new plenum) OR twin throttle body’s.

^ There are calculators on the net about stroke vs RPM, they work it out by calculating the speed of the explosion vs the distance it has to travel i.e. it cant pass mach 0.5 or something (I'm really rusty on this, looked it up years ago) N1GTR, what crank and size bore are you running? Do you know what these kits cost? I've been pondering a new build for a while now, and i was thinking of keeping the compression a bit lower this time (10.5 - 11.0:1) GTR head/ITB's, and stroker, aiming for 250whp with some meatier cams (only after 7500 - 8000rpm limit though, want peak power at 7000).

You probably wouldn't want a MAP sensor with high end cams and ITB's, probably better off with a Q45 AFM. I agree that RB26 head is the way to go, solid lifters, ITB's alot of high lift/duration cams and no vct (adj cam gears on intake and exhaust). With a balance, RB25DE pistons >225whp would be easy With higher rev's you will have to do some research into oil pumps & restrictor setups as well And if you only wanted to rev to ~ 8000rpm, you could get this http://www.spoolimports.com/content/SPOOLN...TROKERCRANK.asp With some thing like that, I'm sure you could net ~ 250hp

um, this thread is 2 years old...

He's already bought the VL, your comments aren't necessary, your pretty much telling him to sell the car he just bought and pay 3-4x as much and get a supra... As for the 150kW comments,. i don't know much about Supra's, But on the same day and same dyno that my RB30DE made 151kW, an NA 2JZ supra with intake, exhaust & other mods made 125kW at the wheels, it was a late 90's model with like 50thou on the clock. Obviously they do and can make a lot more power easier than an RB30e, but they are about on par with a proper twin cam RB30 (RB25 head, RB25 pistons, RB30 Block), and remember a supra weigh's almost 200kg more than a VL, yes of course they are alot better but they also cost a lot more, and are a completely different type of car.

He's already bought a VL...

Twin camming just isnt going to happen, plus it is an obvious mod that you could get pulled up for if a cop knows what he's talking about. A healthy RB30 with a custom intake pipe, CAI pod filter and extractors/highflowcat/2.5" catback exhaust and 20degree's ignition timing on 98ron is worth about 100-105kW at the wheels. Add a mild reground cam (GTS2 spec or similar) and an XF/KA24e Throttlebody (With the plenum port matched) and you can see about 110kW at the treads. With the car like that, it will be a good drive, that is is nice amount of power (and what i had on my p's without any turbo restriction), if you mod wisely like a quietish exhaust (i.e a few large straight through centre offset mufflers), completely enclose your pod and have discrete intake piping (aka not chrome, just black) or better yet keep an airbox with a dry highflow filter, somthing like this http://wiki.r31skylineclub.com/index.php?t...F_Throttle_body (3/4 down the page) using the larger pipe and box from a different model car. The will keep the car looking and sounding stock and therefore no police attention. On top of this, the GTS2 cam operates well with boost, as do all of the above listed mods, so if you are to turbo it a few years down the track, a lot of those mods will still benefit you. For a bit more power and better economy, you can get a nistune ECU (www.nistune.com), and get the engine tuned with the above mods, and you get other bonuses like being able to run a larger AFM which will get you more air flow through your intake pipe when running th XF throttlebody and once again, these mods are still very relevant for a turbo conversion. This will get you another couple kW peak and hold power for longer before it drops off after peak, as well as a WAY better midrange and economy benefits. Then the last engine mod is compression, if you never intend to turbo your car, pull the head off and get it shaved, a bit more compression makes a huge difference on RB30's as they are a bit low standard, and its essentually free power, as you get better economy and more power from the same fuel, this is most ideal as the final mod though (after management) otherwise you'll have to wind timing out of it ont he stock management, and it will limit the aount you could get it shaved... As for non engine mods, DIFF GEARS! VL's have awefull diff gearing and this is why out of the factory, the heaviier R31's with the same power are faster 0-100 and faster 1/4 mile. If your car is auto, 4.11 crownwheel and piston from an R31 pintara, if your car is manual 3.9 from an auto skyline is the most ideal. This makes a massive difference on VL's and if you do it yourself, is a really cheap relatively easy mod (takes about a day <$100) and while your at it, you could throw in a dirty BW LSD, which would be OK in an N/A. And lastly if your car is manual, when you get a new clutch, which i'm guessing will be heavy duty, maybe get a lightweight flywheel, it will go well with your shorter gearing, and i just love them for rev matching and downshifting. Once again, if you intend to turbo, do it right tghe first time and just get an RB25DET HD clutch, they are light under foot and will hold happily with boost, unlike standard RB30 HD's. With all those mods in a VL, you could get a flat 15 with good driving, the car will be very responsive, alright on fuel and should keep you pretty happy for the time being, then you can spend your money on suspension/brakes/car restoration while your waiting for the time to pass .

What engine is it setup for? RB20/25/26/30/CA18/SR20

Hey mate, cheers for that, got it all on and fitted, got an extra couple psi and couple degree's ignition timing. Can you adjust the pump for more flow? Is it clockwise or anticlockwise for more or less?

Definitely fuel pump, as for injectors on N/A management I'm not sure. Due to the extra efficiency from nitrous, it could push your equivalent power (if it were N/A excluding the power purely from the extra oxygen/fuel mix in the case of a wet shot) it might push your stock power past what the ECU is capable of. I'm not really too familiar with R34's but R33's are 270cc which wouldn’t be a problem, it would handle it fine. It’s just what the ECU decides to do when making the extra power, it could richen right up - could simply R&R or worse it could lean out. You said you would get it on the dyno, so you'd be able to monitor all that anyway, so i wouldn’t be too concerned. If you wanted it on the cheap (i.e. without aftermarket management assistance), just retard the timing and fit some colder spark plugs, it will cope with it fine, it’s just the drivability without nitrous that will be effected. This might not be an issue for your mate, if so then just go for it like that, but you might be able to get some drivability back with more ignition timing by making other changes. You could fit the engine with a cooler thermostat from an R33, and modify the coolant temp sensor in some way (maybe add a resistor, so it reads the same resistance at 76degree's as it did at ~ 82-83 or whatever neo's are stock) this would make your engine run cooler but drive the same (without cold start enrichment and bad economy). The point of this, just as the colder plugs (which you should fit as cold as practical, NGK 8's/9's) is to cool the engine & combustion chamber down as much as possible, to slow the combustion process. Much the same as retarding the timing slows the combustion process by moving ignition further from top dead centre for lower initial combustion pressures (therefore slower combustion, as it’s almost like having less compression) and of course lastly, you could just run a high octane pump fuel (do you guys have 100ron up there?) or a fuel additive such as 10-20% toluene (could get expensive if the car is driven frequently). Some of these changes will help with power (without nitrous) as an alternative to retarded timing, but you'd definitely be better off with some form of aftermarket management or assistance - especially considering it could actually net you more power both with and without nos.

Nitrous is great, and its no where near as sketchy as people think, as people above has said, just do it right. All you are doing is adding more oxygen to your engine, its similar to boosting your engine (aka adding more oxygen by means of adding more air). Otherwise if you go for a 100hp shot, without having fuel properly set up, ignition timing a appropriate level etc, its just like bolting a turbo onto your car and running 10psi, you damage your engine, due to the incredibly fast combustion, causing excessive heat and pressure. Also, don't under estimate nos, 50hp isn't 50hp of gain, its 50hp worth of oxygen burnt at a 12:1 ratio. Due to efficiency bonuses etc, that can be up around a 50RWKW gain. If you use a tame amount, you wont have to drive your car around with retarded timing, and you wont have to go spastic on supporting mods, plus it will last twice as long. A 10LB bottle on 50hp will last about 3 minutes before its too low on pressure to be usable, but don't forget, in a drag, you are probably only flat to the floor for a few seconds (when in the power range, not shifting etc) if dragging illegally at the lights, it might only be like 3 seconds of use, down the 1/4 mile, maybe ~ 12seconds of use. That's 60 street drags, or 15 drag runs, at 50hp (estimate around 150kW at the wheel with good flowing exhaust on an RB25DE) With nitrous, get some colder range spark plugs (maybe 7's or 8's if you have good coil packs/don't mind a miss at idle) and set your timing to factory specs. A free flowing exhaust is also a good option, and run the best fuel you can combined with the right rev restrictions etc. Any more than 50-60hp and in my opinion a good option would be some sort of piggy back computer, maybe emanage ultimate? Simply because if you want the car to be fully drivable, not all sluggy and uneconomical with the timing retarded, that way you could control the nitrous with the aftermarket management, as well as have it tuned for with the nitrous - for appropriate timing and fuel maps when in use. I'll be heading back in the nitrous direction (for legal use...) when i get bored of my R33 RB25DE+T, and get my other skyline back on the road. I was thinking my new daily could be a BMW 540iLE (6 speed manual, 210kW 4L V8) an exhaust and 75hp shot does wonders, brings that engine up to around 300hp at the treads (225RWkW) when in the mood for a bit of a squirt (I'm generally quite sedate and like to chug along, which is why I'm not too happy with the r33 as a daily).

It say GTS and has factory GTS wheels, with 4 stud hubs, it's defiantely factory N/A. Looks in great condition, completely stock. Good starter really

http://www.tradingpost.com.au/Automotive/U...ue&AdOnTop=

easy way to tell if its the turbo or the engine is to bull off the breather/oil cap and idle it, if its pissing out fumes on idle and under rev's she's knackered. I've got an R33 in my driveway atm with the exact same issue (factory RB25DET) the rings are just knackered. I've disconnected and blocked all breathers at the manifold and put the hose for the rockers into a ventring catch can. Fills it after a bit of a thrash but i just tip it back in. Most of the dodgy running is due to the fumes in the intake, if you just vent they go alot better, mine doesnt blow exhaust smoke either.

Are RB20det and RB25det head studs the same part number?

Liberty is a much better car than the impreza, and its actually 100kg lighter than you quoted and the handling is superb. You can get about 100kW at all fours with light mods, they can be quite snappy and bonus of AWD. http://www.redbook.com.au/used-cars/detail...id=127676BD2518 I've seen a fair few Autechs around, just gotta wait and snap one up, yeah they're priced similar to the turbo's, I've seen them around $15-20k But they get the 6 speed etc and with around 120kW at the rears + that weight, they'd be worth holding out for.

S15 Autech edition, 150kW Also, i think a Gen 2 Liberty Bilstien Edition would be a better option than an N/A impreza

Still got this?

I'd assume they would just be unplugged, so with a different dash, there should be sockets for the plugs to clip into...