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Discuss all things tuning in this section. News, products, problems and results.
i wanted to ask which is better G35-900 with 1.21 a/r or G35-1050 with 1.01a/r?
i saw dylan 2jz with G35-1050 1.21 a/r which is perfect it just spools at 5000rpm which it not quick enough for me, not sure if he has cams on it.
and i saw alberto bigboost 2jz with G35-900 with 1.01a/r which makes about 80HP less with 2 less psi that dylan but spools 500 rpm faster which is better
i believe alberto engine is 2jz-ge with stock gte cams.
any way is it possible to get the best of the two turbos quick spool and without sacrificing the top end?
i would personally prefer the faster spool time but each to their own and it will depend on what the car is being used for the transmission etc
that is true i also would prefer the faster spool, i just mean what is the perfect combination, would the ar size effect the spool and power what should i expect from G35-900 AR1.01 vs G35-900 AR1.21
im trying to find out how much more RPM would it take spool with bigger ar on small turbo (G35-900 AR1.21) and the same for smaller ar on bigger turbo (G35-1050 AR1.01)
looking at the compressor map i cant tell if there is a drastic difference but the dyno shows a noticeable difference
Well, going from smaller AR to 1 step bigger one within one turbocharger frame size usually doesn't make too much of the difference in spool rpm. Depending on engine components it is normaly 200-300 RPM all else being equal. The biggest impact on spool RPM is made by turbocharger frame size.
Do NOT get hung up on what other peopele are using, and peak power numbers - 99% of the time they're of no use to you.
What You DO need to do is review the other hardware you're using - this is everything from block prep' - girdle and/or studs, piston and rod assemblies - strength and CR, head work and/or cam's, how the vehicle is to be used, what is acceptable and what isn't - the high rpm before it spools/comes on boost would be under this, even the gearing and charge cooling can be critical.
When you've done that, you should have an idea of the compression pressures - boost - you can use and the rpm it can be taken to. That should give you an estimate of the torque and the potential power you should be looking at, from which you can work backwards to estimate the impellor - cold side - required for that and the turbine and housing that will suit to bring the boost in earlier without being excessively restrictive at peak gas flow.
For a vehicle that is focussed purely for top speed and/or drag racing, you can use a more 'peaky' engine with a relatively narrow, high RPM power range, but for a quick road car where low-mid rpm torque and good response is required you may be better to concentrate on mid range torque with a sacrifice of the power potential at high rpm.
I would also warn against taking only the engine into consideration - depending how far you go, you may need to improve coolant and oil cooling - especially in your summer, you may need to uprate the clutch, if the engine is peaky you may need to drop the diff' ratio to make it more useful, brakes may need attention, tyres may need up-grading, etc.