thehelix112

Errr.. I don't know if I'm understanding the question mate. You pick what hp/boost you think your engine can run, pick the approximate rpm the engine will make this boost, plot that point, plot idle air flow point at PR of 1, then draw a line from the second point to the 1st point, then a horizontal line from the first point across to max RPM. This will tell you what efficiency the compressor is working at throughout its working range. Dave

This must've been covered about a zillion times elsewhere on the net. Maybe start by reading the garrett tech info. http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

I have no experience to take this with a grain of salt, but it would seem to be that a: everything 510six said makes perfect sense and b: there are other (some easier) ways to make sure you're leaving the line with as much boost(power) as the tyres can handle: two-step rev limiter anti-lag high stall auto transbrake auto Dave

I think it depends what sort of application you are chasing. 650hp from a L28 drag engine is probably nothing special, but a 650hp endurance racing engine, somewhat more impressive. Dave

My GT35R spins for significantly longer than 3 seconds. More like 30. Dave

Everything is a compromise. I would think that a turbo could be considered mismatched if the engine doesn't make as much hp as the compressor can flow, which indicates that the turbine side is choking things. This is not the case with the GT35R I believe. A friend is making 640hp (dynojet/USA hp) with a 1.06 GT35R on a SR20. The compressor only flows a shade over 60lb/min which indicates to me that the turbine is perfectly happy flowing more air. The 0.82 housing obviously flows less than the larger 1.06. Garret website graph will tell you how much. Dave

If a GT35R is mismatched, then the GT30R that uses the same comp wheel with a smaller turbine mustn't work at all? Dave

I have a Serck cooler mounted in front of my intercooler, not the best idea but meh. I run a thermostat and its only ever opened once at a track day. Track temp around 45 deg C. Good synthetic and its not really needed for most climates/uses. Dave

Nah I don't have one sorry. I have a custom unit based on a BMW rubber dampener. I will be getting one at some point though. Dave

Sorry to thread hijack, what oil pumps are you guys using now? I see curtousy nissan sell a `competition pump', and that you can get std volume melling replacements. Do melling make a high volume one? Back on topic, I am not too sure how the whole spinning up past a rpm when you rev it then clutch it. Given the generic sigma F = ma (same concept applies to rotational movement), I don't see how you can get any chance in rotational velocity without an acceleration (torque). Any ideas where the torque/acceleration would be coming from? Dave

If its got the valve springs/cam to support it, and a decent dampener, 7200. Make sure you have good oil pressure, I just chewed my bottom end bearings because of a dodgey pump. Dave

Sell it and get a corolla. Dave

Plugs are tricky things to read, and I'm not expert. But basically I believe you get a black coating on most things if its too rich. I run on the rich side of things (down to 11.9:1) and I have a nice black coating on most stuff. However the insulator (slightly conical bit on the middle of the plug) should be a nice brown colour if you have the right temperature plugs. When I ran 6's my plugs looked a very similar colour to yours. I don't think you are running rich, but dont' **** around with guessing, get a wideband. I was running 0.023 (0.6mm). Dave

Try to make the join at as acute angle as possible, though this gets less important the further from the turbocharger you get. Dave

Can't hurt to start out lower and work your way upwards. I don't think you'll notice the difference between 6500 and 6800. I find myself short shifting on the road and it makes almost no difference to the acceleration. Maybe start lower and work your way up if you're unhappy? Dave

Depends on a lot of things: How much boost pressure you are running (boost on top of the valve reduces the effective valve spring rate and therefore valve bounce threshold) How balanced the bottom end is (who knows?) Cam timing/duration (no point revving the snot out of it if its not making any more power) Almost definitely others. Dave

AK-Z, Having it near the T/B will mean the compression wave caused by the closing of the T/B is further away from the compressor wheel than if it was near the turbo. Dave

Justin, So because you are flowing more out of the BOV, ie, wasting more air, that the turbo then has to replace before the engine sees boost again, that is better? Maybe if you had a turbo tacho log as well to show us that the turbo didn't in fact slow down as much, and a log over boost pressure as well to show us that the gear-change lag is shorter? Dave

http://www.atiperformanceproducts.com/products/dampers/101/index.htm Good read IMHO. And I'm assuming everyone knows they sell a damper for the L28. Dave

I'm on my way to Laguna Beach tomorrow actually (from Melbourne, Aus). Have a look at a turbocharger flow map: http://www.turbofast.com.au/FlowT3.html The lines with 6 digit numbers are turbocharger RPM lines, notice that for higher pressure ratio and flow the turbine has to spin faster. That is why they produce more heat when asked to compress air more, and more air. A larger compressor spins slower to move the same amount of air typically adding less heat for a high pressure/flow combinations. So yes, you're right. Also, a turbo will make more power if the exhaust side is larger. Dave

All good. Dave

Awesome. Thanks Jeff. I have serious oil pressure issues atm and this time tomorrow will be on my way to California so everything is on hold for a while. Lots of copper shavings in my sump. Stupid 30yo design oil pumps. Dry sump for me. Dave

Sam, I really noticed the understeer tendencies of the locked diff. Don't kid yourself, its shocking! You can however overcome it a little by increasing the rate of the rear ARB relative to the front. I also noticed a big improvement when I added more camber to the front of the car, front end is more than happy to turn now. Dave

Hehe.. good to hear! How much boost are you running again? I just finished on-road tuning mine for 17psi today. Feels fast for about 2 minutes then starts to feel slow again. Gah, damn country roads, you don't really feel like you're going fast til you look down at the computer and see you're doing 5500 in 5th (128mph). I'm off to the land of extremes (murica) on Tuesday and obviously my zed won't quite fit as carry on, so I'm going to a local race track on Friday, drags on Saturday, 9 hour ``cruise'' (evil grin) on Sunday. Dave Dave

2.28 seconds from 3000rpm to 15psi. Not too surprising really, it is just an eensy bit bigger than a stock T3. Dave