Sydneykid

245 rwkw = ~400 bhp At 85% duty cycle that means ~400 cc's per minute of fuel To get a 270 cc rated injector to flow 400 cc's means an increase in fuel pressure to ~71 psi. That's almost the limit of a Bosch 044 (73.5 psi) leaving no room for boost. The best I have seen was 350 cc's and that was at 55 psi (plus 19 psi for boost = ~73.5 psi). Even then the duty cycle was a bit over 90%, which doesn't leave much for acceleration enrichment or hot day running. Personally, I am not that keen on running a standard fuel system at 73.5 psi. The standard hoses, fittings and clamps are not realy rated for that sort of pressure. Fuel fires are very ugly. Anyonme going down that route should look at braided fuel fittings all the way from the pump to the fuel pressure regulator.

Yep, I have allowed for that possibility, the same thing happens when you record it with a video camera. It is hard to show but you can now measure it for around $US350. Kernco make a Digital Laser Non-Contact Tachometer to measure up to 100,000 RPM. You place the reflective tape on the shaft to be measured, aim the laser at the shaft, and press the button for a reading. For turbo you could put the tape on one of the compressor blades and aim the laser into the inlet.

Castrol SAF-XA 75W160:cheers:

Shocks :spcartman

I have read back through this thread and there is one point that I need to emphasise. The "no BOV" supporters put forward the logic that by having a BOV you let all the pressure out of the inlet system. This means that pressure has to be rebuilt, hence "lag". The 'pro BOV" supporters point to the change in direction of the airflow, which has to be corrected, hence "lag". Both have an element of truth in them, that's the difficulty. The real questions is which is better (ie; creates less lag)? In a race environment (without giving out too many secrets) we tune the BOV so that it doesn't let all the pressure out of the inlet. Just enough so it doesn't stall the compressor. An example, say I run 1.5 bar and 105,000 rpm shaft speed, I can tune the BOV so that on throttle off we maximise the compressor rpm (not less than 40,000 rpm) and still hold 0.5 bar boost in the inlet system (between the turbo and the throttle bodies). In practise this is not quite what we do, but it is conceptually sound. So the question then becomes a choice between; 1. Full open BOV, zero boost and 80,000 rpm shaft speed 2. Controlled BOV, 0.5 bar boost and 40,000 rpm shaft speed 3. No BOV, 1.5+ bar boost and zero rpm shaft speed Which gives the best performance? According to our data #2, but others may have different opinions. Not to be overlooked is the fact that we have the throttle bodies very close to the inlet valves. Perhaps in an application where there is a very large plenum between the throttle body/bodies and the inlet valves, it may well be a different answer.

Bummer, I was looking forward to a 20 lap race around Oran Park:cheers: PS; I though I would clsoe with this quote from Peter

What the others have said plus the rear low mount is better for handling, lower C of G and more rearwards weight distribution.

About 4 turns and the marks on the belt line up on mine.

This is what the pulleys look like at TDC on #1. Have a look in the Stage section, there is a full set of manuals and pictures:cheers:

700 cc's = 700 bhp 240 litres per hour = 666 bhp

Let's kill the fan thing................. Are we talking about 1. blocking the airflow into the fan (ie; from the rear)? 2. blocking the output of the fan (ie; from the front)? If you are blocking the rear, then the blades are spining in a partial vacuum, lower resistance, hence the fan goes faster. If you are blocking the front then the fan slows down, because the air is bouncing back (reverse direction) and this creates drag on the spinning blades. When you have reverse airflow (no BOV) it is the same as #2, not #1 (that would be like blocking the compressor inlet) We do that twenty or so times every lap in a race. On the data log I can see how long it takes the driver to apply acceleration (via the TPS). I can see how long it takes for the boost to build (via the MAP sensor). How long it takes for the car to accelerate and how fast it accelerates (via the G force sensor). On our cars we tune the BOV to ensure the fastest boost build and acceleration. It is worht mentioning that we have a PPG dog box which changes gear in milliseconds, so there is very little time for the BOV to open or the airflow to change direction. The real advantage comes when you have to get of the throttle without changing gear. Then the rate of acceleration is very important and that where the BOV is worthwhile. Lastly, on the engine dyno we can actually see the compressor blades turn backwards when we abruptly shut the throttle with no BOV. It is very easy to see using a timing light as a strobe. In fact you can see the large puff of reversion back out the compressor inlet.

Maybe try Nengun, Greeline etc:cheers:

I think Roy hit the mark with his post, airflow in the wrong direction and a stalled compressor logically must display poorer throttle response than airflow in the right direction and a free spinning compressor. To that I would also add that a stalled turbine is going to have more resistance to flow than a free spinning turbine. As for reliability, the reverse direction of rotation (backwards) changes the thrust. Instead of the compressor being forced back towards the core, it is being forced forwards out the compressor cover. This has an interesting effect on the thrust loadings, particularly in a plain bearing turbo. I have had this discussion many, many times since 1989, when GTR's came out with twin BOV's. We always end up back at turbo reliability and performance. The other items, such as emissions and noise, can be explained away with other factors. PS; Personally I prefer the standard GTR BOV's, they don't leak and are free flowing, all that I ask from a BOV.

1. Injectors Rule of thumb for 85% max injector duty in a cylinder engine, injector cc's = bhp 444cc's = 444bhp 444 bhp = 331 kw 331 kw - losses ~75kw = 256 rwkw 2. Fuel Pump This is a flow chart for a number of fuel pumps, the R33GTR fuel pump is on the table, the R32GTR fuel pump is basically the same as the 300ZX fuel pump. As you can see from the graph, the 300ZX fuel pump is good for 225 litres per hour at 13.5 volts and 20 psi boost. To get ~13.5 volts you will need to use a relay and supply power direct from the battery. The standard wiring seems to limit it to 12 volts and I have seen as low as 10.5 volts (bad earth). 444 X 6 (cylinders) X 60 (minutes in an hour) = 160 litres per hour So the standard R32 GTR fuel pump will supply the 6 X 444 cc injectors easily. In fact enough for 625 cc injectors at stretch. 3. Standard turbo's 300 4wkw, an interesting question that one. It's an airflow (which is what makes power) and boost (a measure of restrictions) trade off. The ceramic turbines don't like more than 1 bar for long (hot) periods. But you might get 300 4wkw at 1 bar if you remove enough restrictions (inlet, exhaust, camshaft etc). Most certainly it will be somewhere above 265 4wkw. Hope that was of some help:cheers:

I think Nismo make "hardness up" rubber bushes:cheers:

OK, is that 480 bhp or 480 rwhp? If it is 480 bhp, then that would need to be measured on an engine dyno. That's a liitle more than I would like for standard internals (450 bhp is my rule of thumb), but not extravagently so. If it is 480 rwhp (358 rwkw) that's ~560 bhp (418 rwkw) and that's way past what I would consider to be safe for standard RB25DET internals. Maybe its 342 rwhp (255 rwkw) and someone has simplistically added 40% to get 480 bhp. Plenty of that going around. The 12 @ 118 mph in a Silvia works out around 225 rwkw (380 bhp). We don't use plain bearing turbos so I can't give any comment on the 20 psi from the TD06-25g.

Oooh goody, a healthy debate, it's been a bit boring around here lately. I don't know about you but I don't want to be rebuilding my road car turbo as often as Jap D1's. As I said we do it on the race cars every 2,000k's, it's a pain in the ass and expensive. We used to do it on the Sierras 3 times in a race weekend, but they ran 2.5 bar and no BOV's. That's evidence. I didn't claim Nissan put BOV's on their cars for performance, I believe they did it to improve turbo reliability. The increased service intervals (on BOV equiped cars) being my evidence. Why do you think Nissan fitted BOV's? NVH? I don't think so, at the low standard boost levels there wouldn't be much to gain from that perspective. Emissions, if this was a atmospheric BOV versus recirculating, then emissions is certainly an issue. But we are talking recirculating BOV versus no BOV, I am stuggling to find any emissions advantage. If I refer to the Nissan workshop manual I can find no reference to a faulty BOV as being the potential for excessive emissions. That's evidence I appologise for introducing reliability into a "performance" discussion, but a failed turbo does lead to pretty low "performance". To finish first, first you must finish.

Replacement bushes (alloy or polyurethane) are NOT the same as "pineapples". Replacement bushes simply replace the standard rubber bushes with a firmer (hardness) material. In the case of aluminium that is solid, which is not a good idea as it can lead to cracking of the subframe mounts. Nissan designed the rubber bushes to prevent this and to lower the NVH. Polyurethane is a good mid ground, it is much firmer than rubber (45 versus 90 duro) but it has some give to keep the NVH within reason and to prevent the chassis cracking under the vibration. Pinapples are "tuning" device, by placing them above and/or below the subframe you can tune the amount of antisquat. More squat for drags gives better traction and faster launch. Lots of antisquat for drift to decrease the traction and enables easy/earlier slide. Pineapples do add a worthhwhile amount of extra rigidity when used with the standard rubbers. But they make no difference to rigidity when used with aluminium bushes and very little difference when used with polyurethane bushes. Hope that helps

How much power did you loose?

The standard head gasket should give you the correct amount of squish, as designed by Nissan. ie; you should not have to deck the block or the cylinder head. I have seen more than one engine develop more detonation after a thicker head gasket was installed. Squish is one reason for this, the other is the thick (metallic) head gasket itself creates hot spots. Potentially all around the combustion chamber circumference. Not a good idea. I would much rather spend the same amount of money (as a thich head gasket costs) removing restrictions, rather than increase the boost to make more power. If you MUST reduce the compression ratio, then polishing the combustion chamber gives a better result for the same cost.

Rule of thumb for 85% max injector duty in a cylinder engine, injector cc's = bhp 370cc's = 370bhp 370 bhp = 276 kw 276 kw - losses ~55kw = 221 rwkw PS; if you had done a search you would have found this calculation ~221 times. The search button is your friend.

How does one go about resetting the ECU in a Stagea? Does the old disconnect the battery and stomp on the brake pedal work?

Yep, the whites are input cells.