Miffed and dissapointed....

[sciroccosi]

Had the mk2 golf gti on the rollers yesterday, its a 2 litre 8v engine using the AGG bottom end and a re-con pb head, last year on the same rollers with the old 1.8 engine and head it did 107bhp at the wheels @5500 rpm which is around the 128bhp engine bhp mark, but this time wi the new head and bottom end it only did 95bhp @ the wheels at 5000rpm and 87bhp @5500 rpm, the chaps very very good vw men say its the cam thats not right and to use my old cam from my original pb head,all the fueling, timing etc etc is all set up fine, could it be that the original cam is modded or are there different versions of the pb cam, thing is it goes really well low down at the min but crap at the top end of the rev range, i hadn't noticed as i havn't been driving it hard due to running it in anyone any idea lol..cheers simon

[duncancallum]

dirty clogged air filter or poor airbox?

failing that I would time the cam up with a dti as its not uncommon to see factory grings a few degrees out

[sciroccosi]

I did new filter etc before i took it, ive changed the injectors and fuel pressure regulator today for my old ones which if the numbers on them read logicaly they are bigger injectors and it seems miles quicker and i mean put yer back in yer seat quicker so hopefully thats done it.might wait until bous time at work in march and treat it to a kent 270 degree cam and see how it goes but im 100% happier now than i were yesterday lol, hows your scirocco goin pal mines tucked away wi a 79 mini 1100 special in the inlaws garage. im gonna do some work on it now the golfs sorted out

[MikeH]

What cam is in it? Did the guys at the rolling road check the cam timing? Lots of bottom end but nothing at the top would suggest the cam timing is too far advanced.

There's only one type of PB cam. Should have about 10.2mm of lift. If you've used the Mk3 GTI cam, that probably only has 9.6(ish) mm of lift.

If it's a VW cam, set it up to the standard marks. If it's an aftermarket one, check that it's at equal lift at TDC (inlet and exhaust lobes should be mirror image of eachother). That's not 100% accurate, but should be a good place to start from.

[sciroccosi]

What cam is in it? Did the guys at the rolling road check the cam timing? Lots of bottom end but nothing at the top would suggest the cam timing is too far advanced.

There's only one type of PB cam. Should have about 10.2mm of lift. If you've used the Mk3 GTI cam, that probably only has 9.6(ish) mm of lift.

If it's a VW cam, set it up to the standard marks. If it's an aftermarket one, check that it's at equal lift at TDC (inlet and exhaust lobes should be mirror image of eachother). That's not 100% accurate, but should be a good place to start from.

everything is set spot on since ive changed the injectors and fuel pressure reg its like a different car now so im guessing was something on the fueling side but it shifts now lol yeh its a standard PB cam as ive used the PB head etc

[steve]

I've seen this happen with Polo GT's when they're had a new cam in. Assuming yours is digifant, have you set the timing up properly (think there's an FAQ on club GTI) or just static timed it?