rob82

Sounds like piston noise to me as well - maybe a shrunk piston skirt.

Very possible - we intend on running more compression with the F6 we are building atm, aiming for around 850rwhp on E85.

For street use - I would always go with more response/torque than top end horsepower so smaller turbo or smaller hot side or both. My thoughts are that you should select a compressor that will flow enough for the desired horsepower. The selection of the exhuast housing has alot to do with the fuel being used as you can generally make the same horsepower on a better fuel with a smaller hot side than on pump pump fuel with a larger hot side, this way your maximising torque/average power. Turbo selection has alot to do with exhuast back pressure. The more the backpressure the more the stress on the engine but if your fuel is good enough to put up with it than its not a problem. Bigger turbo's genreally mean more horsepower at a higher rpm which means redesigning the engine package. Are the cams big enough, will the head flow enough, will I need more cubes for the power to be usable etc etc.

I tuned a BF F6 with the usual mods, was making 347rwkw on BP98 on 15Psi of boost, changed over to E85 and we ended up with 398rwkw on 17psi. The car actually ran 412rwkw at summernats. From what I've seen it requires %28 more fuel to get to the same AFR as BP98. Its obviously a much slower burning fuel(as most alcohols are) so in only applying the fuel changes to the tune the boost crept up about 3psi over the pump tune. The XR6T's run about 12deg total advance on 15psi on pump with the right mods and I was able to advance the timing another 4degrees and add 2psi of boost. More timing netted no reward so I left it at that. I could have leaned it out but the customer was happy at that. My thinking is that with good fuels you can choke the exhuast side up (put on a smaller housing) without loosing any power. Remember your still flowing the same amount of air on the cold side to get to the required horsepower you just need more fuel as the specific density is less and so is the rate of vapourization. The other thing to note is that exhuast backpressure reduces with greater ignition timing so choking up the exhuast side on good fuel may yeild exhuast backpressure equivalent to a larger housing on pump fuel with less advance. Overall it took me about 10min of tuning on E85 to realised this stuff is good. If the fuel system is large enough it will get results similar to that of VP109 - which is about $200 per 20 liters.

As has been said - keep the standard intake manifold, increase the compression up to 9.5 - 10:1 (definately de-burr the cahmbers) , keep the camshaft duartion smallish (260 ish) but use agressive lobes with fast ramps - may need custom grinds (I would talk to Tighe cams and ask what grind were in Lukes car - they will know) and use good quality valve springs in order to keep valve float at high rpm under control. The larger the duration of the valve event the lower the dynamic compression. IMO every camshaft install should be acompanied by an increase in static compression in both aspirated and turbo applications. Remember that you have a large turbo thats is only going to start breathing around 4500rpm so peak cylinder pressures are going to be around 5500 - 6000rpm which is quite high meaning you have mechanical advance to compensate for the high compression. Not sure if its available for RB25's but have you thought about HKS Vario cam or whatever its called, may give you more inlet advance than factory cam phasing. Good way to dial in more inlet advance/overlap down low and pull it out so as to not sacrificing top end power.

How are you guys finding the results from the flow bench testing correlating back into the real world power figures? Its just a few of you guys were talking how NA cam and head setups are completely different to turbo head and cam setups however your still deriving results using vacuum based flow assessment.

Has anybody cam doctored any of name brand Cams. I think for the RB30/26 you could probably get away with aggressive ramps as the rev limit is 1000rpm lower than most rb26. I would like to know who has the greatest area under the curve for the same advertised duration.

You dont need fuel coolers - all you need is a properly setup fuel system. We never run two fuel pumps especially 044 pumps at the same time - that means you'll be sending at least 6L/min of fuel flow to the front of the car all the time. Your better off putting a walbro intake pump or whatever intank pump you prefer and run an addtional high load swithched 044 pump inline with a bypass line around it - dont forget a check valve. I've seen this setup run over 420rwkw on an xr6T using E85 with fuel line pressure of about 78Psi. Remember you need about %28 more fuel flow with E85!!

If it is an r33 crank than no as it should have the wide 25mm oil pump drive face.

I tend to agree - I had a an RB26 in an R32 RWD making about 240rwkw and in going to an rb30/26dett with the 2860r the difference in torque is massive. I think you will find the torque comes from the larger rod/stroke ratio than the cubes. I often found that with the 26 you were constantly serching for the right gear to use but with the 30 you just leave it in whatever gear and put your foot down. The only real way of increasing torque is to increase compression ratio - I wouldn't do this with std cams tho. You may be able to get custom pistons with a bit more dome to get the comp up to 9.5:1 - make sure you deshroud the valves and clean up any sharp bits in the chamber tho. Failing that I would get a smaller turbo charger.

435kw out of GT35?????

Works fine on std r32 GTR Ecu - using a generic autronic three port solenoid.

Are you sure the VCT is working at all - I havn't seen that work before. I would have though that you would kill you top end - the engine has oil pressure right???

I'll grab those dyno sheets when I go back to work. In regards to the rb25 manifold - I was only mentioning that I have seen that amount of flow through the standard manifold - that car went on to run 129mph in a VL so the horsepower numbers are on par with MPH.

Sorry Guys but I fail to see the point of doing this modification. The factory rb25 intake manifold is good for at least 500rwhp worth of flow as I have seen. It will also give best cylinder distribution and will also create the highest port velocity due to the long runner length - which will result in a better midrange, earlier boost potential and not to mention better fuel economy. I have dyno sheets of an aspirated XR6 with a TO4Z turbo conversion which I tuned a couple of months ago - as some of you are aware the aspirated XR6's have a dual length intake manifold to promote bottom end torque. The dyno sheet shows the difference between the long runner and short runner in a turbo situation and I can telll you the difference through the midrage is huge not to mention the rpm at which the desired boost level was acheived. If you interested I could find dig it up and post it.

You could still lean the mixtures out to 12:1 but if your getting knock then back the timing on the cas 2degs and see how you go. Are you sure the base timing is correct - be aware that you need to check the std ECU data to do it properly as it has idle ignition control - which means it varies timing based on desired idle rpm.

The first engine might not cost that much but by the third your will start to be getting to the $30K mark.

dOes it take into account transient fueling?

I have seen this on one specific ECU where it would carry the LTFT data through to open loop - real pain in the arse. There is another PID than just AF learning I think it is AF correction and the only scan tool I've seen that can pick it up is the Nissan version of MDM100. Also how is it doing boost control in a BNR32 ECU is it a single row of DC?? I have used the std boost control throught the s14 ECU but didn't know it was possible in the BRN32 ECU - but I've never really looked for it.

The 555cc Nismo's are the best injector for your application - they are by far the injector of choice, the sards are crap. Besides you only need about 8psi more base pressure to get you to th equivalent flow of a 600cc Inj.

1) The spring in the actuator - the higher the required pressure usually means the greater spring pressure ie a 14psi actuator usually has a higer spring pressure than a 10psi actuator. 2) If your boost source to your actuator goes to your intake manifold than you are actually creating a manifold leak under vacuum if you have a boost controller. Your boost source should be post IC pre throttle body. You will also have better boost response in this configuration as your not applying negative pressure to the actuator before coming onto boost. 3) I'm guessing you have just lined the acutator rod hole up with the wastegate flapper stub and didn't apply any preload to the flapper - this will cause bad boost response and a few other issues.

You dont want to be running an acuator at less boost pressure than the spring pressure. I know the HKS item is meant to be 14psi but your will probably see a little bit less sometimes due to IC pressure losses along with a few other things. You really only want to put more preload on the acuator not less. The proper preload for most actuators is a half to a full hole - that is once bolted in you should have to pull against the spring pressure to get the rod over the flapper stub. Hope this makes sense.

I've seen engines lose torque/power by using that approach - usually large duration camshafts and unreactive chamber shapes cause this. And generally less boost in spark ignitions engines is better but I have seen cases that are contrary to this as well. Diesel engines are quite the opposite though - the more boost the better. Its really a case of giving the engine what it likes.

Sorry but a gutted / "highflowed" cat will always flow more than a proper metal/ceramic substrate cat no matter what. And no I'm not endorsing it!

What is the specified piston to bore clearance on those pistons - also what compression do they come up to on a standard head/gasket?