To replace the 9A engine in my trackdaycar, I've found an ABF which I will collect next week. I wanted to fit the 9A head because it already has the catcams, but the engine will be revised anyway, so I wanted to ask which head would be the best, or if it just doesn't matter? I've got: The KR head from my original 1986 1.8 GTI 16v engine in good condition; The 9A head with catcams, also in good condition; The original ABF that comes with the engine, condition unknown. Obviously if the head is going to be any other than the 9A, the Catcams will be placed in the head that is going to be fitted.
Confirm what the cast number is on the the cylinder head of the 9A. It is over the 1 and 2 intake ports as 051103373 and might have a letter after. Please confirm.
Then if the 051103373 cylinder head is standard, you would be better off using a 051103373D cylinder head and transfer your cat cams if they are the same cat cams used in the ABF engine code. There are several threads here, showing the differences between 027103373E, 051103373 and 051103373D.
No real world inlet flow difference between any of the 051 castings. The bigger exhaust valves on the 9A and later KR version of the 051 isn't worth worrying about. The KR 027 flows the least. Go for either the one with the cat cams already in or the nicest casting. Making sure the cams are timed properly is much more important.
Why do you say use the earlier 051 head in favour of a later 051D head with its benefits? Both standard. So if kept standard and used in a trackday car, with catcams ( of unknown spec), I would have thought it beneficial to use the cylinder head with the greater benefits? It was you who demonstrated the 373D casting flowed more than a 373 casting after all. Curious as to why the suggestion.
Catcams 7661221 http://www.catcams.com/products/cam...NGINE_id=86&CAMSETUP_id=1115&Language=english Not of unknown spec
They should be mentioned in my car-topic, so I hoped I didn't have to clarify lol. I had to search for the number too
I also use an internal gear on those cams to further fettle the lobe centre angle and initially set up the whole lot with a DTI and a degree wheel. Then more fettling on the car, to balance the cylinder fill for idle ( 1100 rpm ) and top end ( 7600 rpm). Most of the lumpiness has been dialed away at idle. I believe the camshaft was mentioned here. My ABF cylinder head is fettled as a road/track day spec, however my CR is still near standard. I still run the original plenum manifold but this is likely to change to a set of ITBs there were shared here. That car is used to commute when I fancy something raw and is very drivable in heavy traffic.
The Golf is track only, as it doesn't really pass MOT demands anymore. Also, it isn't nice to drive on the road, or I'm just too old 6 points belts, noise, low, hard suspension etc. I have an adjustable pulleywheel on the cams as well but it takes quite some expertise to set it up. Anyway, I got the offer in for the head work and damn, that almost doubles the price of the rebuil. The thing is, I want to clean the (9A) head either way, as I don't want any metal particles to go through the engine, so that work is to be paid anyway. In that case they can just do the ABF instead and mount the cams there.
Yes, initial set up of the cam is important as a going in point as it drastically affects the cylinder fill, which determines the characteristic engine torque for the type of engine. Then fettling after to get the cylinder fill of the cam in the right place. On a modern car, I have the luxury of shifting cam phasing via the calibration or even cam lift. Takes some experience to get it exactly where you want the torque for a fixed cam. At least it is not an 8v! A track car still needs to transition between a low part load RPM from say 3500 to 4000 rpm to the redline in some gears. So the calibration needed to achieve the response you want will only be as good as the hardware chosen. On a dual purpose road/track car as mine, those requirements increase as you also spend lots of time at low speeds, idle or stopping and starting and may need to use RON95 fuel to drive around. The latter has am impact on the chosen CR.
