This is mainly aimed at those people running Schricks, or hotter than standard cams in their 2L 16vs... My car has 268/276 Schricks & recently went for a weekend tweak on TSRs rollers. Despite moving the cam timing a fair way, peak BHP remained constant at 185atw, but curiously it didnt lose power, even with big swings? The car feels its best running standard cam timing out on the road IMO (setting equal lift on overlap etc etc), but we are a little mystified as to why it peaks at 6800rpm & then tails off quite sharply... Do you all run standard or close to standard cam timing?? IanB runs the same cams as mine but his K-Jet car revs harder (to 7800) & makes the same power as mine... Not sure if the 268/276 combo is too tame for an ITB'd car, or particular to K-Jet as my idle is really good in comparison, even at 800rpm, yet id expect a TBd car to be mega revvy given the extra breathing, which it isnt .. Considering the excellent road manners the car currently has im tempted to eventually go for straight 276s if these may increase peak BHP a little?? Im wanting to rev to 7600 maximum on the track & utilise the entire rev range, but the current set up seems to be holding back a wee bit... Anybody got any words of wisdom or advice??
Chris, i know its not a 16v but my 304 in the 8v revs upto 7.5k at the moment and is still pulling so hard up to that i reckon you can easily get away with more lairy cams in a TB'd engine, without comprimising idle/low down power i havent a clue when it comes to timing up a 16v so cant say whether its that or not, but considering IanB's revs much higher (1000rpm more) and has the same cams, there must be something not quite right,
So you did go then Chris 185 ATW..............Niceone If it were me as a road and track machine it's the best compromise For mainly track use then it's get your wallet out matey and go for the Schrick head and 304 cams plus ARP internals..........those ITB's will love it!! Unfortunately as with our cars now is the time things get realy expensive [:^(] I think your set up is ideally suited as an everyday car. Ian
Yeah, Pete took the car for me Ian... Graham is still a bit mystified though We cant get or heads round why it doesnt rev out as strongly as your K-Jet cars given its on TBs. The good idle & lack of anything happening when you swing the cam timing has made him suspicious of the cams themselves He has known Schricks to be supplied incorrectly before, so even the best can make mistakes.. Edited by: chrismc
Im no 16v cam expert but it certainly sounds like your cams could be of different profile than what you think they are. I cant see how a K-Jet car would rev harder than one of the same spec on throttle bodys
Easy enough to check the cams as they have the part no's stamped on them - i have several schrick catologs so can check if you post them up. Usually, equal lift at O/L is pretty much spot on, used to run my old engine with a pair of 276's at this spec, slight mods around this point cam move the power about a bit but not usually that dramatic, couple hp either way, slight change of shape to the curve, cam advanced usually giving more top but this is engine spec dependent. TB'd car will take LOADS more cam than what you have and still drive lovely (trust me on this one ) but a hike in CR would be useful for this also, then you have to pocket the pistons...expense time Also TB'd cars will only beathe if the engine wants to - and the cyl head is critical in this regard - is yours a good one ? Also, as I have said before, its still a new engine, maybe will loosen up a lot with a few more miles Rob
Cheers Rob........... Im sure the engine still has a bit of loosening up to do. The head is a TSR jobbie, to the same spec as Grahams/IanBs so should be fine.. Do you know where the part no's live on the cams & if I can see them without removing them? Might have a gander whilst im out looking at my clutch/gearbox Any idea what I could expect to gain or lose in terms of BHP/torque & how the curve would move going 276 inlet??? Cheers for your help......
Have you tried playing with the inlet tract lengths on the throttle bodies at all ? Some answers might come from there. To be honest i'd get it to a more sophisticated rolling road where they can measure the fuel curve for example. Or actually get a torque curve at all.. Maybe this sounds silly but are you sure you're getting WOT on all the throttle bodies equally and that said quantity on fuel on the map is actually being deliverd ? Edited by: madmk4
Chris I think Bill ran 304 cams or thereabouts at some stage in the Jetta on a hydraulic head but went back to his Crane cams. Probably is worth checking cam spec but I reckon a bigger spec cam and solid head is the way to go for your set up.........still you can't accuse you car as a poor performer! I'd save the money myself and keep it as it is... I was discusing the same issue earlier in the year but the cost just spiral........ [:^(] Ian
With a pair of schrick 276's fitted (10.5mm lift ones, which are unlike current spec 11.5mm lift ones), my car with old engine has run at Stealth and I think the power curves are on GVK's website - take a look. With a milltek 4-1 exhaust fitted (looks same as tsr 4 branch) and the above cams, I did quite a bit of playing around with TB trumpet length - very marginal differences from 40mm to 120mm in 20mm increments. Cannot go longer than 120mm on my ibiza because of bonnet clearance but of course there's loads of examples with other cars where much longer than this has brought benefits (saw a 2002Ti once with 3-footers !) Cam part no's vary - on some they are on end of the cam, on others they are cast into the cam itself between the lobes - so would have to take rocker cover off Cheers Rob Edited by: RobT
Bills old Jetta motor couldn't rev enough to make use of the wild cams. Its likely they would have been faster than the 260-odd cranes if the engine is built for them. I can appreciate where Chris is, most of us have been there - keep the car as a fantastic flexible car that can be driven daily and to/from track, loads of fun - OR - evil Rob/Chris/Ian comes out and wants a fire breathing 100% track focussed weapon. Its a tough call. The next step is big dollars. If your interest is purely trackdays and the like (non-competitive) then your car is ace and as Ian says, probably enough. If you want more power then its probably more cost effective to do a 1.8T transplant than tune your valver to the next level. I wanted to go racing and wanted too stay in the under 2L class so I had to tune the valver - and it cost a packet - but what an engine ! I'm so disappointed you guys didn't get to see this at Brunty. As always its about deciding what you want and its not easy. Cheers Rob
Or do what I'm doing now, and lowering the FD for greater on-track performance More cost effective than throwing more money at the engine.
Maybe I could get the F.D sorted if the garbox falls to bits when I take it off...... The other thing ive noticed is that the car (with these cams) has always peaked early RPM wise in comparison to others with a similar spec, but had very strong torque...(as per the dynoplots @ GVK-MOTORSPORT) Peak power has always been a wee bit down too.. Another reason to think the cams are a little mild perhaps??
That's were we are now I suppose, I know I'll hate that lower FD the first Monday morning I'm driving back from Worcester at 5am But, it'll be great on track I hope. Edited by: GVK
Chris, has yours got the internal verniers, as I thought it was these that made all the difference to the 268/276s..
It must have if TSR set it up to run equal lift at OL - if not, they havenot Cat cams have the cam-to-cam verniers built into the cams - VERY nice Rob Edited by: RobT
hi chris , may be you could be down a little on compresion on one cylinda. pop to halfords and pick up compresiontester and have a play . i reckon you got week valve springs and your valves need laping in , deck the head while its off. just a apinion. i have seen adrian at tsr play the jetta cam timeing and gain 20 brake . paul h
Not really thought of that Paul, but the block is nearly new..... I dont think its so far down that its majorly sick, more a question of where the power is produced...
