Hi, some of you may know about a few problems my mate and me are having with his track car as featured in Golf+. i thought i would start a new thread for anyone interested in the car and the cross flow head. In short the engine is a bit of an unknown as he had it built but was not told what actually was done, the head has had massive porting and a one off cam was made but first dyno results were very dissapointing with a peak output of 150bhp. recent investigation has highlighted a low compression reading on number 1 cylinder and after a leak test the problem seems to be the inlet valve not sealing properly along with slight leaking from number 4 inlet valve. the head will be off by the weekend and all will be revieled so infact even though the first dyno results were dissapointing , now we know there is a problem, once its sorted we may be suprised here are some pics if anyone is interested
We're always interested... Low compression will obviously drop power off, so thats the first fix. Did'nt you say you had some flow figures for the head? Looking down the ports, they look just cleaned up from the std one's I've tested, but that's no bad thing as the std crossflow port size is big enough to suit the std valve size... it's the work thats been done to the seat & throat area thats the important starting point. Cant yr friend get the exact details off the guy that did the work?.... c.r, cam spec, cam timing? At least you'd then have a starting guide. The install looks very nice.
we may not be able to save the head !! the engine builder has destroyed the valve seats, nearly all the inlets and exhausts are ruined, it is now at another company who is going to try and save them and repair some other faults with the head. but going on our rr results even with a f*^&%d head it looks like there is good potential, plus we have been informed that the rr we took the car too is very old and gives very low resluts so things are looking up
Unlucky chaps... New inserts will cure it, but at a cost. You may of course get away with just replacing the few un-cutable. The problem that may occur tho is... if they try to re-claim the seats buy cutting them deaper, they will loose the seat profile, and also loose some c.r, plus, the shimming will now be out on the cam!... there's very little easy in engine building! That's good news re the rollers... stay positive, and remember, numbers arnt everything... if it performs as well as you want then you cant ask for more... apart from more power when you get used to it!
i have not actually spoken to them myself but from what my friend has told me they said they can fix it but for how long it will last they dont know, this confused me a bit as surley they can replace the seats and all will be sorted, im going to have a word with them myself. the shims for the tappets were also made from cheese so they are making some new hardened ones once the seats are done, if this does not work then im really sorry but the 20v will be put on :-(
By that is sounds like they maybe re cutting the seats but it'll be thin... so they're thinking they may burn out, that would be a waste of time. Your right, new seats will cure the problem as a correct seat width and angle can be cut.. sorted. And a new seat insert can be fitted at any depth, so the seat cut can be at the top to allow for the correct profile, and the valves being further up in the chamber will keep the c.r up. 7mm lash cap shims are available, no need to make something at increased cost no doubt.
right update time , we got the head back yesterday , all the inlet seats were replaced and the exhausts recut, they really could not believe the state of them, a few of the seats were not even cut straight we have been lucky that all the valves survived. new shims have been made and the cam is a 300deg standard kent one. we checked the cr today and what with all the work done to the head its actually slightly less than standard so the head is going back tomorrow for 1mm to be removed to hopefully take us to around 11.3-11.5/1 once again the low compresson has lost us more power so fingers crossed things are looking even better now, i just wish we would have saved all these problems and just done the head ourselves.
Which Kent one? I would'nt use more c.r than that on cast pistons... as you have standalone you at least have control, but dont do o.t.t with ignition timing, and keep the water temp under tight control. Sounds like progress tho, great news.
the cam is a gs3 supersports , yea ill keep the timing well down with the temps , we should have it back together by tomorrow so ill let you know how she runs
Can you tell me why the kentcams dont use alot lift just 11,9mm instead of 14,4mm catcams or 12,4mm schrick? Schrick isint far of kentcams, but catcams 2,5mm more. Could you tell more about it
Probably to minimise mods to the head - lower lift can mean STD valve springs and no clearance issues. Modern trend seems to be for more lift and less duration though - bleeds off less compression, more emissions friendly, etc.
we got her back together, timed up the cam , reset the sensors and done the initial setting up and running friday night and straight away i could tell the difference, she revs and sounds like no 8v i have ever heard before ! we have not taken her out yet as she has no tax but as soon as that arrives we will get out and do some mapping, i have great hopes now as the top end before was basically knackard and still made 150 bhp my inbuilt ear dyno estimates around the 180 mark maybe more so there maybe life in the old 8v's yet, its a shame we had not sorted the problems out before the mag write up but at least its done now
Here is a quick before and after vid, they are a bit poor quality but will get some better ones soon, you can hear the difference in the way they rev. http://www.youtube.com/watch?v=AsQayPuyyEw http://www.youtube.com/watch?v=rHTTyd35vgI
I'd have thought leaving the Mk1 catch tank would have kept the weight lower? Seriously nice work there, and yeah, big difference. It sounds like it's got a sore throat in the first one.
