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My 944 1uz-fe V8 swap
- Thread starter Eldavo
- Start date
George Elliott
New member
924nutter
PCGB Member
Good point but that would have required a complete re-engineering of the cam-shaft drive whereas Porsche's solution just requires a new peice of bike chain and some fresh cheddar every now and again. I presume the cheese is so that the system can be calibrated by mouse.ORIGINAL: Woodsport Thanks Mike, i do this for a living so that's why it is moving at this pace and standard, it'll slow up as i get to the bodywork stage though. Hi John, on the contrary, all of Toyotas Helical driven quad cam engines also come as "vario cam" or VVti, a hydraulically fed gear on the end of the cams adjusts the whole camshaft relative to the helical gear, all ECU controlled. I could have used the VVti version of the 1uz but i prefer the simplicity of the older unit.
George Elliott
New member
Surely the lag on that must be immense - measured in minutes rather than seconds? Oli.ORIGINAL: Woodsport True George, but nowhere for turbos themselves sadly, unless i mounted them at the rear with their own oil pump system... this isn't a 944 but you get the idea....
Diver944
Active member
Not ideal locations, but maybe not as bad as you'd think. Remember the base engine is not a puny 2.5 litre 4 banger but has 4 litres through 8 cylinders. That's an awful lot more airflow from the piston sweep to load up the exhaust pipes before the turbochargers.ORIGINAL: zcacogp Surely the lag on that must be immense - measured in minutes rather than seconds?
George Elliott
New member
In any given application, the swept volume that drives the hot side is proportional to the demand at the cold side. As Oli said, the lag.........I thought our crossover was long too. As a general rule small turbo's seem more efficient than large for very complex reasons. (A 996TT works better with twin small units than one big unit) Its interesting that rear setup is a twin, they could have been routed to a single. Maybe thats why a twin scroll single seems to be more efficient too? In any case, I was being a bit flippant - you have enough to do with na V8 Paul. Keep up the good work George 944tRemember the base engine is not a puny 2.5 litre 4 banger but has 4 litres through 8 cylinders. That's an awful lot more airflow from the piston sweep to load up the exhaust pipes before the turbochargers.
Forgive me for more questions - I know very little about forced induction systems. However the turbo works by harnessing the pressure from the exhaust and then using it, via turbine, to compress the inlet gas. If the turbo is far from the engine you would have to (in sequence) wait for the flow in the exhaust to build up to a point where the turbo is spinning fast, which means a longer wait as the it will take time for the higher flow to reach the further distance. You then have the time taken for the turbo to accelerate, which will be the same. You then have the time taken for the pressure generated by the turbo to build up in the inlet manifold (and other pipework). The greater the volume of this pipework, the longer it will take to build up the pressure, so further away = more delay. A bigger engine will blow more gas down the exhaust, sure. But a bigger engine will need a bigger turbocharger to feed it as it will consume more air in the intake manifold/pipework, thus meaning the turbo will have to work harder to build up the pressure. This will surely negate the effects of the larger engine? As I said, I know very little about forced induction so, if the lag really is small in such an installation, my logic must be flawed somewhere. I guess my question is, where? Oli.ORIGINAL: Woodsport Also remember lag is not the result of how far the turbo outlet is from the throttle body, it is a result of how quickly exhaust gas spools the turbo and how quickly that turbo produces boost, the distances from Turbo to engine would only delay throttle response by a fraction of a second (the speed boosted air takes to travel the length of the car- which would be milliseconds) The turbo "lag" would essentially be roughly the same as i'd guess the speed and volume of exhaust gas hitting the turbine would be roughly the same as it is coming from the head.
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