aDrew_C

What do you ultimately want to do with the car? IMO an RB25DET NEO is better than an RB26DETT for a moderately tuned street car. For a serious track car, RB26 has all the performance parts readily available to make big power.

Obviously there are other reasons why you don't see such engines used in motorsport... The point is that how the ignition affects the drive shaft is what's important. In the case of a rotor the rotor itself ingites 3 times per revolution but the eccentric shaft is only rotated by one of these ignitions for it's revolution. The exact same effect as a two-stroke. This is what mazda seem to have based their definition of a 1.3ltr high revving engine on. I somewhat agree with their definition because the driveline is what affects how the power is output, the fact that the rotor spins three times slower can either be viewed as being similar to having more pistons or as mazda would like to see it, the same "pistons" on their next cycle. You're right though, comparisons to piston engines don't really mean anything... unless you're trying to figure out what category rotarys should be lumped into for motorsport.

Yes a 4 stroke would, but not a 2 stroke. Also remember the two stroke would also be significantly lighter and smaller than a 4 stroke, maybe even weighing less than a 13B.

First of all, I don't see how it matters as far as comparisons go if they state 1/3rd the capacity and then 3x the rpm. The two cancel each other out... sure for motorsport things are a bit different, but surely the low rpm has to be taken into account. I don't see why they should say "well it's your fault your engine doesn't rev, not ours, change the design so that it does rev", because that seems to be what is being proposed here. If they'd made a 3.9L V6 that couldn't rev for shit and wanted it to compete against lower capacity engines then that would be different. This is not what's happening, the design of the engine lends it to be strong in one aspect but adversely weak in another that just happens to directly correlate with the aforementioned strong aspect. I don't see how the hell it matters! It's just twice as much half as often.

RB25DET = ~228Kg Dry with turbo, manifolds etc RB25DET 5 speed = ~90Kg Dry SR20DET = ~150Kg Dry with turbo, manifolds etc SR20DET 5 speed = ~72Kg Dry S15 6 speed should be a little more And some comparison engines with turbos/manifolds 2JZGTE = ~268Kg VH45DE = ~230Kg CA18DET = ~130Kg VQ30DET = ~162Kg LS1 = ~174KG

JZ's are definitely not lighter than RB's. You know how everyone says JZ's are over engineered? Well that definitely comes at a price, they're build like truck engines and aren't far off in weight. Not that the RB is much lighter, around 50Kg heavier tops. IMO, go with a VQ30DET. Quite a bit of a headache, but an RB will be as well... VQ's are apparently pretty on par with SR's weight wise, and should sit a little further back being only 3cyl long. More torque than an RB too...

FD RX-7's are brilliant cars, they wouldn't handle like they do if you put a 6 cyl in the engine bay. Nothing wrong with a rotary at all. I don't give two shits about capacity and rpm and all that crap; power/torque for the weight and dimensions of the engine is what means the most in a performance car. You can't seriously say an iron block I6 is a better package? I hope mazda have success releasing the 16X rotor. With more power, torque, efficiency and less weight I might just be tempted to get a cheap FD and put a 16X in it when they have been around for a while.

25NEO is probably the best standard RB out there for a street car.

....where?

The -7's are an outdated turbo, the -9's eclipse them in every way - more efficient, more power for the same response. That seems pretty simple to me...

Well personally I wouldn't use the 26 plenum because of how it tapers off toward cyl 5-6, definitely a limitation which while proven to be 'ok' on rb26's making big enough hp is definitely still a limitation. If you're going with a new plenum why use something that isn't designed all that well in the first place? For a fairly reasonable price the Greddy RB26 plenum is much better, retains the itb's too.

Just to clarify, the plenum in the op is a JUN copy, not a Greddy. Jun no longer make these plenums. I'm going with a genuine Greddy in a few weeks.

If the pistons lower the cr with the standard headgasket then no headgasket will be thin enough to raise the cp. You will have to have the block decked with the cr of the pistons and thickness of the headgasket in mind. Have to look at the deal you are getting on these pistons; is worth it really worth it over some 9:1 pistons? A GT3582R is a very efficient turbo and with a well built engine you shouldn't have any problem pushing 1.5bar with 9:1 compression.

Don't know about the brake pads but aren't 300zx 280mm rotors ie same as R32 GTST. R33 are 297mm.

If your car is mainly a street car then why do you want lower compression? Even though you have a pretty old technology turbo right now I'd still stick with 9:1. That means not going overboard on the headgasket thickness too.

Minor stretch is a great thing from my experience. I run 235/40 on my 18x8.5" up front, 245's would be a definite downgrade to cornering and on an 8" rim would be sloppy as fark just like a falcon... funny that seeing that's what falcons have on their 8" rims. For a 10.5" 18" rim I would personally use a 265-285/35 depending on guard fitment and what's on the front.

Anything below +15 should look ok on a brn34. +10 is a bit more ideal but if the rims you want are only available in +15 then it won't be a big deal, inner clearance will still be fine.

Since when are 275's stretched onto 9.5" rims? I've got 255's on mine and it's hardly a stretch at all. For the op, mate if you're going wider guards then go for it. Use an offset calculator to work out the best fitment based on your current rims, just try to have them stick out 20-25mm more but with minimal to no lower amount of inner clearance. +20 sounds about right but double check anyway.

Pretty good but a bit over the top. You've got to wonder what a side vent that big would be used for on an FR car. The smaller vent at the bottom would be enough for rear brakes, then there's the f40 type vents, the ones on the bonnet seem too far back to be cooling anything but I guess they would have to have a purpose, but then there's the back ones again. What are they cooling? Function criticism aside I actually like it as far as over the top body kits go.

Just adding another point to the debate. If everything else is equal you have to consider the extra weight as a negative for twins. Yes if you want some crazy unstreetable power then my points about singles don't hold as true. For people who care about response twins are fine in bolt on replacement form because of the cost saved and the standard look to the engine bay, but for under 400rwkw a good single setup makes more sense when it comes to what matters to me - torque curve vs weight. Going by that merit an LSX is the best option for the money..... what was that I said about this thread getting a bit out of hand?

This topic has gotten a bit out of hand, but if everyone wants to argue twin vs single, might I add the weight issue. Twins may mean smaller turbos but two small turbos still generally weigh more than one bigger one. Then there's the extra intake piping and exhaust dump/front pipes. IMO twin turbo only has three obvious advantages: 1, supposed efficiency gains - not so true these days. 2, if the turbos are setup sequentially - again, how many sequential tt cars have been made after the early 90's? and 3, cheaper upgrade path (for already tt cars) as well as keeping the standard look. So really the only reasons to go with twins on a GTR is either for regulation reasons with motorsport, cost, or to keep your from being defected.

Has anyone had issues with a tank of E85 forming vapour and running badly after being left for a day or more? I spoke to my mechanic about using e85/98 blend and he said what one of his customers tried (some 'ET' stuff in 20L drums) had consistency issues. The car was filled up with it, tuned, left on the dyno overnight and the tune was way off the next morning. Anyone else have issues similar to this?

LS2 supercharged.... could be done cheaper than a RB30DET build I reckon and get you less weight/better weight distribution not to mention the torque.

Have had my standard clutch pushing 185rwkw for almost 4 years now. The clutch looked very new though, got it with the gearbox that came in my halfcut and the clutch had definitely not done 75,000k's... more like 5000, if that. It's just started to slip, going with a Exedy sports organic (32GTR push type) since I'm putting on a bigger turbo.

I'll have a R34 OP6 0.63 turbo up for sale probably next week if you can wait.