burn4005

My take is Higher compression engines are: -more thermally efficient, less heat out the exhaust (lower EGTs) which spools the turbo slightly slower. BSFC improves. -better off boost due to torque improvements -won't eat as much boost (dynamic compression) as low compression engines do. on a large engine with a small turbo (8374 on a 3.2 is a small turbo in my mind) it makes sense as you won't get much boost into the motor anyway before you overspeed the thing. I just hit the speed limit of an 8374 on a 2.6 at 8000rpm and 27psi at 490kw. so a 3.2 with the same VE% at around 6300 rpm you'll have the same boost limit. if you rev any higher you'll either have to taper it off, or run less boost, as the torque produced is really going to work your gearbox. its hard to know where the 1.05a/r housings limit is, as we were stonewalling the compressor and had a compressor speed limiting function in the ECU, adding boost wasn't really making any more power as the ECU was just pulling the target down anyway. it would be interesting to throw a 9174 core in there to see what happens with the 1.05 as it would be running near peak efficiency where this one is falling off. I wish I had an EMAP sensor, but the wastegate duty was quite telling. at about 7000rpm and up we had to really start ramping the duty in to maintain boost target, whereas below this point it was pretty flat. compressor efficiency was really starting to dive up here so to maintain shaft power by increasing exhaust expansion ratio it looked like this: (I'm using a 4 port 12w MAC valve and a 7psi spring in the gate, also using solenoid deadtime function in the emtron so real duty is about 12% more) running the thing on E85 also makes the decision much easier.

Probably need more crank prime at warmer areas

and for shits and giggles, here is the 91mm compressor. looks like a damn good fit too if you're heading for more boost.

here is my dyno log over the 8374 compressor map. the 8374 is a pretty good match for an rb26. I've moved the air flow scale slightly to make the turbo speed lines line up better. I would also expect the pressure ratio to be slightly higher due to air filter and intercooler pressure drop. I'm just using MAP here. you can see why they snap on so hard, it goes right through the peak efficiency zone when it's spooling.

It's a powerhouse racing one, and I'm using a sard venturi pump in place of the tiny stock one for the saddle transfer

it is! part of me wanted to crack 500kw but the rest of me is over the moon (and i'm over 650hp so I'll claim that instead)

Forgot to mention that the 490kw was done with Bosch 1650s, stock R34 fuel lines, stock fuel rail stock nissan filter single in tank pump (pierburg l3lm at 17.5v and pwm control) Aftermarket fuel hat Diff Fuel pressure drops from 45 to 42psi from idle to redline with fixed pump speed but can be ramped in to keep it flat. Pressure at pump outlet is probably much higher!

Dyno today 87mm rb26 on e85, 260 9.15 cams 8374 on a 6 boost 490kw at 27.5psi. 126k rpm full boost at 4600rpm haven't played with cams or closed loop boost control yet.

front cut rebirth job?

they just replace the stock ones. no difference in sound. you can tighten them up with the preload screw if you want a bit of compressor surge but otherwise they're silent.

true,I'm not using it, want to be able to change turbos easily without mucking around in future. its a bloody small hole for a 9180 compressor though considering its the same size as the one on the 6258.

lol the only Garret that might displace my EFR is a med/large frame G series if/when they ever get released.

Big single turbos sound f**king stupid without a bov. I got sick of it after about 60 seconds when i tried it on mine (hooked BOV lines to pre-throttle source to keep them shut) https://youtu.be/d6I7_Or4w7c?t=1m18s

I hope you called them as you need 38mm adaptors to suit the GTR piping (part number 5238). and they are NOT a listed part on their website or through resellers.

GFB do BOVs called mach2 that fit the stock location. model number is T9105 for the pair. they do make outlet adaptors that are the right size for the GTR recirc pipe, so they're a direct replacement but you'd have to call and order them direct from GFB, not from a reseller. about $350 from memory. I've got two installed in place of the stock ones that failed a boost leak test and they are working great. they were a direct fit, plug and play,.

The absolute best fluid unless you are going to change it right before every track day is Castrol SRF. its a Silicate Ester fluid, gives a slightly softer pedal feel. but its wet boiling point is MILES ahead of the competition. (270c for SRF, 204c for RBF660). they all start around 320-325 dry, but as soon as they start absorbing water (which is immediate, they are hygroscopic) the SRF is the better fluid. its dear as poison ($110/L) but flushing brakes all the time sucks. and ends up being cheaper due to way less flushes.

Sparesbox have 20% off on eBay all the time but I'm not sure they actually can get their hands on them/have stock

And Nord lock washers

Also I ALWAYS use inconel bolts on the turbo flange.

put up the precision turbo data Lith.

yea the 8374 getting close to all in at 26psi/65%, but the 84 is just getting started. literally off the chart... might be hitting a sonic stonewall or something so they stopped mapping to the right, still fine rpm wise.

https://bmw.spoolstreet.com/attachments/c92a58335a9c242d64ec466cfc9172ee_zpsniwwkwsu-jpg.13075/ Man I wish the 8474 was a thing.. maybe too good to be true. 20-25-30psi 77-84-91 lb/min also, G series hopefully scales well. Med and large frames are going to be beasts. if the G25-660 is smaller in every way than a gtx3071.

on an RB26 12 teeth is plenty as it is operating at high speed when ignition timing is important ( and at high speeds the errors are less) under boost/load 1 degree makes a magnitude more difference than under vacuum). it depends how important rock solid idle timing is to you (we are talking ~1-2 degree error though). on a slow revving, high torque high compression engine (diesel for example) where the power strokes are slow and strong you would want more teeth. 36+ I went a 36-2 as i like the engine starting one crank sooner and my engineering OCD got the better of me. my kit came from JHH racing, they weld either a 12 or 36-2 wheel to a 1000hp ATI balancer and supply a sensor and bracket that bolts to oil pan flange. excellent bit of gear.

that is correct, the sync signal occurs only once every two revolutions of the crank, and the edge of it occurs between the same crank teeth on every sync event. the edge always occurs in the 10 degree window between 300 and 310 (of the crank wheel), so it drifts around by a few degrees. so what you end up seeing is the cyan trace moves slightly to the left and right as the belt stretches/cam to camshaft coupling wobbles. This is why when you get to high tooth counts (60 tooth wheels) you always run a missing tooth on the crank so the reset is done based on that, as if you don't have a missing tooth you are telling the ecu to do the reset on the next crank tooth after a sync signal. and if that sync is wandering by 4/5 degrees you're in danger of the ecu taking the wrong crank tooth as the crank reset. with 12 tooth crank, the gap is plenty wide (30 degrees) so you can be sure the sync will always occur between the same teeth. the upper limit of time per tooth depends on the response of the sensor (my crank sensor (ZF GS101205) will do 15khz under ideal conditions, the only other limit is how small a resistance you use for the pullup. (15khz is 75000rpm on a 12 tooth crank, or 15000rpm on a 60 tooth crank) the falling edge is always very steep as it is a low impedance short to ground by the sensor (open collector) and thats why you should always use it as a trigger edge as it is much more consistent. The rising edge starts to look like a shark fin as it takes some time for the voltage to rise again after the short to ground stops. A 1k ohm pullup will rise much faster than a 4k7 pullup. so at very high speed it might not make it all the way to 5v before the hall triggers again. Shark fin: In a good ECU this isn't a problem as you can set the trigger voltage threshold, so as long as the trigger signal rises to say 2.2v, then falls to 0 it is counted as a trigger event. I am using the internal 4K7 pullup in the emtron and don't have a problem at 8800rpm, I scoped to to confirm voltage rise was fast enough to get well beyond my 2.2v threshold, otherwise I would have used a 1k external pullup instead. the earlier sensors (GT101 etc) had an issue with the Schmidt trigger design which is required so the hall effect trigger thresholds are self adjusting. So if you had missing teeth it could cause issues as there was a very sudden change in event spacing time. the newer sensors (like my ZF one) don't have this issue. its also very important to have as small an air gap as you can to force the hall effect voltage hysteresis gap size in the sensor to be much wider, which also helps to avoids false trigger events. mine is only ~0.4mm from the trigger teeth. If you have a large air gap, it is a weaker signal so the Schmidt trigger needs to be more sensitive so you have a larger chance of false trigger or missed trigger events. Hall sensors are fine, as long as your tooth pitch (spacing), height and depth match the requirements of the sensor. the more teeth, the bigger diameter you need. a company called Spectec make extremely high performance hall sensors that can cope with tiny tooth pitches where a Cherry just wouldn't reliably pick up teeth. (like trying to make a 36 tooth hi-octane style kit) a VR sensor doesn't have any of these issues, and the faster the trigger wheel goes the better the signal to noise ratio gets as the signal amplitude increases. it also crosses zero as the trigger point which provides perfect accuracy, rather than an arbitrary 2.2v which isn't as precise as you're relying on "catching" a falling edge that isn't perfectly vertical.