SKiT_R31

Detonation is less of an issue on an N/A engine, and i always found i could increase the ignition timing ALOT and never had detonation issues with stock compression. If your engine was to have detonation issues, you could always just wind the base ignition timing backwards, making the ignition map on the ecu the same just less a few degrees accross the whole range, which is all you need when running lower quality fuel. Alternatively you could get some colder spark plugs, etc. The threads you are talking about would be for the turbo version, and i bet the users werent on stock boost, so it would have been a case of not being worth the drop in boost vs power increase from the more ignition timing etc, since you cant up the airflow of an N/A engine, i doubt you would have any issue (esp considering N/A's have alot of legroom as far as extra ign timing is concerned, whne stock).

Did you end up getting it? Mine didnt have a limiter, had alot more timing in the top end, far better fuel mixtures, sharper midrange (change in vct?), and was alot happier over 6000rpm, seemed to work really well with my cams. I've actually still got it, but for some reason it's dropped cyl 1, cant see anywhere inside it where anything may have happened and the plug is fine, would anyone know if the chip can be transplanted into another ecu and who can do it?

yes, goes off its f**king head, 98ron fuel is fine, had one on my 30de when it had lower compression (a tad more than a stock 25de), went fine.

If you use the R31 Auto gearbox, there will be no problems, engine mounts are the same, it will all bolt straight in no problems, the only hastle will be wiring, which when you do it, remember to feed the injector loom power, most people overlook this and have endless issues. If you want to fit the r33 box, expect alot of issues, different wiring & computer, different tailshaft, dont know about gearbox mounts...

I'll give you $550 for it right now, posted to tasmania (7010). Sorry its less again than what you were asking, but this is the average price these sell for unfortunately, it's to replace my old kkr430 which i paid $500 for brand new, but that has since spun a bearing. I'm guessing this is one of the oil only kkr430's (some came out water cooled? let me know if your interested Thanks, Dan

I've got a set of stock R33 rims you can have for $100...

whats the specs on your water meth injection? I've been looking into it, using a siemens methonol injector and a microtech MF-1 Microfueler ecu, cheap as chips. if you've got the engine out of the car, why dont you just change the slugs? Dish in higher power applications is a big plus, and if your after big power, it would make sense, you might be eble to get some 25det or 26dett pistons, or for lower comp - even 30e pistons would be better... anyway, i reckon you'll be able to get some good numbers out of it, im assuming its an r32 rb25de?

dont decomp it with a spacer, it ruins the squash, loses you power with minimal benefit for knock resistance. With tech these days, you should be able to make the same power with the higher compression as with lower compression, befrore you need forgies. You'll make more power from stock management, or with aftermarket management and a good tuner you can make just allmost as much power as the stock internals can handle anyway - and a decomp wont make that any better, it will just hit you with the same n/a squash issues (which arent ideal for boost) combined with making less power per psi due to the lower compression. that said, the answer to your question, you need decompression plate (i think 0.7mm) and 2 standard head gaskets, which will drop you to about 8:1 (which is too low for a 25 anyway, as normal rb25dets are 9:1) thats a 1.7mm increase. you'd be better off with a copper headgasket, thicker than standard (1mm) at ~ 1.8mm, its a bit of decompression, puts you closer to the rb25det stock compression, combine it with some colder plugs (7's or somthing) and it will be spot on.

People underestimate the power of a colder range sparkplug, I'm definately a fan esp on n/a + turbo 30's. I run dirty old 30e+t with bcpr7e-8's, with upgraded ignition (bosch GT40) with a 1.1mm gap boost above 12psi was missfiring. At 8psi, no issues, pulls strong and smooth. Question though, should you be running the best gap you can achive without missfires? or does it pay to decrease the gap a little extra to achieve a stronger spark? (or is it sumply a case of, if the spark can jump the distance, its no difference). Also, anyone know anything about indexing plugs on the old twincam rb? I've got an high compression N/A custom RB30DE, and an RB25DET, you generally pick up a few kw from indexing, and i like having all cylendars equel. I currently have the N/A plugs facing between the intake ports and the turbo facing between the exhaust ports. Anyone know?

Compression. cams lower usable compression at the lower revs, which is where compression is the most likely to cause issues, combining compression with an emanage (meaning being able to adjust ignition) allows for a decent increase for some nice power, combine with some colder plugs and a good gasket for a good boost.

Sorry, havnt read the other suggestions, but... extractors and piggyback computer, help economy and get a smidge more power, if you got an emanage ultimate, might be able to get a bit more power (with more ign where needed - usually in the higher rpm for n/a) Alternatively (or as an extra) ; Cams and/or Headwork, i.e. more compression from bit of a shave and a thinner say copper gasket. even one of the second options (all your going to get for 1k) will give a good increase in power but is harder/more of a pain, first option will make an only just noticable difference, with a bit better drivability and economy. How big is the TB/AFM on the 34's?

probably an hours labour, but they're not likely to take the car for a thrash to find the best suited timing, would just set it to whatever you asked. Otherwise you could pay for dyno time, or a local street tuner but the gain vs cost might not be worth it.

take off the centre coil pack cover on your engine, on the cyl 1 coil pack (front) pull back the black insulation and clip the timing light onto it (ensuring the arrow is pointing towards the plug). Now undo the 3 screws on your CAS (just loose so you can turn it, dont completely remove), and start the car (cas should be warm and idling at 750rpm), point the timing light at the harmonic balancer (big centre pulley off the crank) and pull the trigger. The red marker (first) is 0 degree's, and it goes in increments of 5 degree's. Standard it should be on the FOURTH marker, 20 Degree's is a advanced is a good start so that should take you to the FIFTH marker. Advance or retard the timing to net you the best drivability, pending your fuel and engine, dont push it too far, because any gains will be lost if the sensors pick up detonation. 98ron E10 does a good job imo, for increased ign timing on stock factory rich engines.

how much?

more info? Sedan, Wagon? Turbo i assume? Stock or modded? White 1986 R31 Wagon, Low King springs, 4wd shocks (stiff), nolathane bushes, R31 Ti wheels, re-shimmed lsd, RB25DET excedy HD organic clutch, RB30e + T, custom turbo - KKR480 exhaust housing and rear wheel (.69AR) and Garret T04B centre bearing and front compressor Housing, running 12PSI, singlesided FMIC, R34 BOV plummed back, R33 RB25 Crossover pipe, AFM in boost (for more resolution), progressive cooler piping - armidillo bends, VLT injectors high flowed/higher fuel pressure for 280cc operation, 280cc remapped ECU, Malpassi Adjustible fuel pressure regulator, Bosch 044 external fuel pump (noisy), fuel surge tank, cold heat range plugs, Bosch GT40 coilpack, NGK silicone ign leads, 180thou km on engine -has perfect 180psi on every cylinder (compression test), 200thou on chassis. Setup was made hoping for 200rwkw, and uilt to look sleeperish, hasnt seen dyno yet. The gearbox is original S1 30e, doesnt enjoy the power, runs fine in gear or with casual shifts, 2nd gear synchro is worn (cant quickshift second at high revs without a crunch) and reverse has a chipped tooth, so it make a clicking noise - runs fine, oil has been replaced and is clean not silver. sort of thing you are after?

if your going to get cams, i would definately reccoment getting both, combined with adjustible cam gears. Higher compression generates more heat, so to lower cylender temps, you will want to get the exhaust out just as quick as your getting intake air in, otherwise you will not only lose some of the gain from the intake cam, but you will lose power from having to lower ignition timing. Also, as strange as it may sound, a turbo ecu and injectors are a good option for the N/A route, not only is the power and air flow more matched with mappings, the fuel mixtures are better (so you wouldnt need an safc unless you wanted fine tuning) but more importantly, n/a ecu's have alot of ign timing down low, wheras turbo ecu's have all their timing uptop (i know you would think it would be the other way around). But on a high compression motor, the pinging is going to be in the low revs, and with your only ignition timing adjustment being the base timing, to stop pinging down low, you will lose power up top. Also the DET ecu's have a much better rev limiter . I've got 255deg cams with 8.3mm lift on my 30de, with twin throttlebody's (so it can breath) it makes peak torque at 5000rpm and peak power at 6000rpm, which then tapers off until limiter (at the time it was restriction) - if you ask me thats perfect, i wouldnt go any bigger cams for an rb25. So aswell as that, i would reccomend (if your after performance) letting it breath some more, im sure you could figure somthing out with the 2 into 1 thing the 25de's have, give it 2 throttles or somthing, but if the engine cant breath up top, you will lose out with your cams and higher compression - if the cylinder isnt at atmospheric pressure by the time the intake valve closes, working the same way a boosted car works but in reverse (vacuum instead of posetive pressure) the engine will have a lower dynamic compression ratio. So once again with the compromises, you have higher compression down low, its able to breath, might have higher timing depending on the ecu you use, under load in low revs is where the detonation will be, so lowering the timing to compensate for that will lsoe even more power uptop if you have a lower dynamic compression because the engine cant breath enough. (but once again, cams help alot with this, with overlap lowering compression at low rpm) keen to see how it goes - good luck cheers

11:1 sounds like a good number - no sure what the stock compression is on the neo's, but 10:1 sounds about right, is this on stock management? I dont know how the neo would react, but you should also fit a thinner head gasket. Also, providing your not a greenie, fit some colder range plugs, say some 7's, it will help cool the combustion chamber so you have less detonation so you wont lose ignition timing. Also, higher compression engines can be a bit thirstier, so it could be happier with some higher fuel pressure down the track (depends on how far you go). Are you going to fit lumpier cams? Cams cancel out higher compression, for win-win trade off with a shave. ta

PM'd

About 10.5:1 with the stock gasket. what your asking isn't a good idea, shaving the head can ruin squash, which combined with the fact that rb25det pistons sit recessed the the rb30 block means you will get hot spots, which will make the engine aweful at that high compression ratio (will overheat, need retarded ignition timing and extra fuel). You need to deck the block all the way which will bring the compression ratio to about 12:1, which is manageable with 98+ ron pump fuel and good management/tune. You might be able to get a reputable machinist to open up the chamber to reduce compression (whilst p&p'ing) but probably not the way to go. An alternative is using rb25det pistons, decking the block, shaving the head and running a thinner head gasket, which might get you up around where your asking (in the 11's) but i couldn't know for sure as no one has done it. A benefit of this is you could then purchase oversize forgies, increase capacity by ~ 50cc (for max oversize) and have lighter and stronger pistons (lightweight helps revs slightly with stock unbalanced motor and rods, combines with forged rods and a balance and it should be quite a weapon.) not sure if im babbling, but the point is, the compression you will get from the 25det pistons is the most you will be able to get with them recessed the way they are. I'm assuming you want the 25de pistons for a cheaper build, so I'd recommend leaving the head as is, depends on what power your after - good flow in and out plus cams will see you 150. Though it would be smart to do the deck shaving while the block is out and bare, since its not overly costly compared to what it would cost in the future when you want more power of hit problems. I would prefer to do that and then decomp it with a thick copper gasket, than go with the recessed pistons with any higher than stock compression, as the hangover will be more costly.

will you still take 50?

Front facing plenum, Greddy style, has 80mm TB bracket, comes with 80mm billet throttlebody, these are known for dodgy casting, has had dodgy spots between water jackets tig welded and is ready to go. $500 RB20-25DE/T or RB30e/+t clutch, Excedy HD organic, these clutches hold reasonable power (rated to ~240kw flywheel i think) and have a good feel under foot, safe to ride etc, i have the same type in my 31, rb30e+t, this one has never been used. $300 Stock RB25DET injectors, 370cc side feed $50 Got some R34 GTT brakes, front and rear, discs and calipers, includes 5 stud front and rear hubs/drums etc, calipers and hubs in great condition, discs have some surface rust - will need machining, was originally for S13 brake and stud conversion. brakes were sat on grass for photo's only, have been stored in shed for some time. offers? prefer to sell together... 4 x 114.3, set of R31 Skyline Ti rims (15"), 2 have decent tyres, 2 are low tread. Have had the clear coat removed and have been polished some time ago, with a go over of some metal polish would come up like mirrors again, they look sweet on silvia's etc, good offset. great condition $180 4 x 114.3 14" rims, off somsort of nissan (stamped into them) these have no centre caps as i lost one, do have the other 3 but it looks much better without imo. No tyres (2 still have tyres on them, but bald) no gutter rash or scrapes. $100 5 x 114.3 16" rims, nissan S15/R33, no tyres, a few scratches but should come up allright with a clean etc (brown ooze is tyre grease) $150 5 x 114.3 16" rims, z32 300zx rims, good tyres all round, rims in top shape, could do with a wash... $250 After cash, or offers from some decent 4x114.3 rims, for a silvia or 31, in 16" or bigger, even wtb rims if anyone just wants to sell, offset for silvia/r31. RB30e head, has been dismantled, clifters cleaned, crack and pressure tested, and everything properly torqued back together by workshop, has also had surface machined ready to go back on block. Head came off for prepping to go on a block i baught, but didnt end up using it, head had no heat or warp damage. comes with monotorque acl head gasket, and afaik stock cam. $150, want it gone

last time i checked, running an aftermarket ecu was also illegal..... I would much prefer ITB's + MAP, but i can see why you would want carbies... and the induction/exhaust noise would be different, and you cant say for sure that you would get more power out of EFI, maybe economy and drivability and flexibility (weather, atmosphere etc) but it can be cheaper and a whole lot easier with carbies. Esp if you were to have some rediculous cam setup, aswell as other modifications, where you would need a damn good tuner to get good power (and lets face it, its hard to get a tuner so passionate to sqeeze every last kw out of a car by spending hours dicking with injector timing etc.)

... shit... lol feed it triple trumpeted webbers or even SU's and it would be allright though Wouldnt be hard to custom make a manifold, would be better to start fresh, and make a short runner manifold feeding diectly to carbies instead of modifying the dirty 30 manifold to suit a 25

oh yeah my bad, didnt even think of that

Build an RB24DE, using an RB25DET block and RB20DET Crank, This will give you the extra cubes without the longer stroke = happier revs. Their is such thing as an RB24e, which is an RB25 block, rb20 crank, rb30e pistons and head, plus carbies, revs to 8k.... Not sure what rods were used... rb20det (?) then you could put the max oversize pistons into the rb25block and nearly see 2.5L again , though smaller pistons can be lighter, which would be better for more revs. I think RB25 block, RB20 crank, RB26 Head (ITB + Solid lifters), lightweight rods and pistons, combined with the lightweight crank all balenced correctly should see some nic3e revs . I actually had been pondering building somthing like this down the track, out of spare parts i have, with RB30e Pistons and Head, rb25 block and rb20 crank, becuase i can, then feed it stock vlt gear and it would purr along nicely .