Compression ratio
Discussion
Max_Torque said:
Firstly, assuming you mean 3.0bar gauge, i'd not start with an audi 20v engine......
(the 5v head is really poor for charge motion, and the extra valve curtain area is pointless at high boost)
The main problem with that engine is the lifter bucket diameter which from memory is only 24 mm and that restricts the cam acceleration to the point you can't get much lift or valve/time area in a given cam duration. This removes the advantage of the extra inlet flow from the 3 valves to the point it has no more power producing ability than a normal 4 valve engine but with plenty of extra complexity. I did do a ported head, big valve engine for a customer once and it went well enough but just not worth the time and effort for the potential results. A normal 4v engine would have 32-35 mm lifters and although inlet flow is a bit down on the 5v you can get much bigger cams in there.(the 5v head is really poor for charge motion, and the extra valve curtain area is pointless at high boost)
As with pretty much every damn thread here of late....seriously lacking in useful information and with a vague question.
As for 20v, that still gives no real information as to which engine that is, because there are 4 cylinder and 5 cylinders engines with 20 valves that have been used in Audis.
So no info on actual boost ( gauge or absolute ), usage, the engine, fuel, ability to tune, hopes, dreams, whatever etc etc
As for 20v, that still gives no real information as to which engine that is, because there are 4 cylinder and 5 cylinders engines with 20 valves that have been used in Audis.
So no info on actual boost ( gauge or absolute ), usage, the engine, fuel, ability to tune, hopes, dreams, whatever etc etc
Mignon said:
The main problem with that engine is the lifter bucket diameter which from memory is only 24 mm and that restricts the cam acceleration to the point you can't get much lift or valve/time area in a given cam duration. This removes the advantage of the extra inlet flow from the 3 valves to the point it has no more power producing ability than a normal 4 valve engine but with plenty of extra complexity. I did do a ported head, big valve engine for a customer once and it went well enough but just not worth the time and effort for the potential results. A normal 4v engine would have 32-35 mm lifters and although inlet flow is a bit down on the 5v you can get much bigger cams in there.
Exactly, VAG were really grateful when Direct Injection became a thing, because that mean't they could quietly drop there stupid 5v heads without a loss of face! (because you can't, practically, get 5 valves, and injector and a spark plug to all fit!(Also the small bore on the 5v engines means it's pretty pony at the best of times for an N/A application.....)
For a high boost turbo, the issue is the lack of squish, and no land area to control the end gas dynamic compression, this means it's det city, and that means running low static CR's. Ok, for a drag engine, perhaps who cares (max boost, max RON, retard spark, cross fingers for the 9 sec it takes to get to the finish line) but for a race (or worse, street engine) it really makes for a terrible engine.......
Def not related and the engine im talking bout is the 1.8t audi 20v agu engine.
What id like to know is:
Is the engine worth building get get high hp and can the engine handle high boost cuz im running it now with 1.5bar boost and doing around 320hp with stock internals id like to know what compression ratio i can run and if it would be worth my wile to open it up and what tipe of hp can i expect
What id like to know is:
Is the engine worth building get get high hp and can the engine handle high boost cuz im running it now with 1.5bar boost and doing around 320hp with stock internals id like to know what compression ratio i can run and if it would be worth my wile to open it up and what tipe of hp can i expect
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