Just driven my bros 8vgolf, and my 16v is boring compared

[flusted 0]

there used to be a dyno graph on club gti of a 8v and 16v torque figures both standard cars. 16v showed same if not more torque lower down

Also later golf 16vs had the 50mm which was ment to boost bhp figures

[boost monkey 0]

yeah that's right flusted, the 16v application of any engine (as long as the size is the same) should have the same torque as the 8v version, and then above 3000/4000rpm depending on engine, the torque curve just goes up further.

 

Using some simple maths, a 50mm inlet flows ~42% more air....which come to think of it, seems like quite a lot!

 

[b:fzndhh5e]cross-sectional area of 42mm inlet = pi(21

[CrazyDave 0]

Boost monkey, you've been into those books again and learning stuff :) get down the pub with all the rest of the students :lol:

 

But looks good to me. My mate keeps trying to give me a 50mm inlet for my valver, but TBH i'd rather stick to the 42mm to keep what little bottom end torque it has intact. Don't like revving the old gal to much as its all getting a bit rattley.

 

As for FI applications, the air flow / runner length / pressure wave charging etc is not anywhere near as important as with NA due to the pressure. Think of the manifold as a pressure vessel and when a valve opens the air doesn't need sucking in, it rushes in. More air into the same cylinder area (+ more fuel of course) = more torque and hence more power (oh and a big grin :D ).

[Yandards 0]

I have no reason to not believe that the K series mentioned does make the 251bhp the tuner is refering too.

 

If you look at CNC heads figures they do seem to suggest that the 1.8l 16v units are capable of producing that much power, at no point is the rev line of the engine mentioned (Again 16v units do tend to like producing silly power at around 8-9k mark)

 

As for the lower bhp figures between the rado and the Golf KR powerplants I dont know why there is a 3bhp difference on what is an identical powerplant aside from the larger flywheel.

 

David, I do agree that a larger diameter flywheel should not result in a lower bhp figure as it is only a store of energy after all but that is the only difference between the 2 engines aside from the exhaust system. (Which might be the cause)

 

Good figures Boost monkey. As for the why, the 50mm manifolds were introduced to raise the above 4k rpm power delivery on the Golfs and dropped after a short period due to the torque loss at the bottom end. The 16v manifolds taper throughout the length of the runner causing an increase in gas flow when the valves are closed due to pressure reflection in the runner, this is by design and is intended to increase gas flow speed.

 

FI is a good leveller but as with all things the best design for an intake manifold is with very short stubby runners and large tapered plenum chamber, or in other words a 16v manifold is rubbish for FI :)

 

Flusted, be good if we could get hold of those figures although VW did optimise the 8v for low RPM torque and 16vs by their characteristics produce most torque higher in the rev range. I do still firmly believe that 16v has more torque than an 8v most of the time, it just does not feel that way.

 

The main point of me posting the article was to reinforce that 16v head design is more efficient and produces more usable power and torque accross a wider rev range than a equivelant 8v unit.

[flusted 0]

there is another difference but dont think its down to it but the later engines had a different head design, smaller inlet ports and larger exhaust ports

[boost monkey 0]

^^ That won't help scavenging. The inlets normally have to be larger than the exhausts iirc, or at least the inlets need to have more lift.

 

That's why the KR has piston cutouts on the inlet side as they life more than the exhausts do.

 

BTW BEST THREAD EVER!!!11111 :D