Thought it about time I added my bit to Tim's build thread...
Tim and I hatched a plan a couple of years ago to build up an 8v he had been collecting parts for over a number of years. It was initially going to be a conventional 8v with throttle bodies at the rear based on a race head Tim had bought. To cut a long story short Tim got stitched up when he sent the head to be checked over by someone claiming to be a VW specialist, who claimed Tim's race head to be scrap, but in fairness he did Tim a "good" deal on an exchange head...so good I declared it junk when Tim dropped it down to me for flow testing, with valve seats that had done many thousand miles, a spark plug thread insert that pulled out when I took the plugs out and race buckets that had been shimmed by Stevie Wonder...thankfully they don't operate on here, but many have caught a cold in his hands.
Anyhow, I re-claimed the junk head for Tim but told him it wasn't up to scratch for what he wanted for a proper race engine and suggested the crossflow type head could be worth a look at. From there on in we embarked on a series of flow tests of the many variations...swirl...non swirl...German...Mexican...Tim sent so many I lost count, but a lot of the flow data can be found further back somewhere. We settled on a non swirl German casting in the end...I think!...Tim Know's them better than me...he's got less to think about than I have!...but we hatched a two tier plan which will eventually see a proper big valve head built up, but in the mean time, and based on all the flow data I had, we wondered just how close we could get to 200hp on basically std valve sizes as I've heard so many times that a big valve or big exhaust valve is needed to make power....read on to find out how close we get...
Tim supplied me the parts he had that he initially had planned to build up himself, but I fancied the challenge of seeing where we could take this so talked him into letting me build it for him. The block came in good nick but the blue had to go...didn't it Tim!...well it would have clashed with the car!
...looks much better in JMR orange!
In went a bladed crank secured with ARP main studs....
...along with steel H section rods and some Wiesco forged pistons. There were for a turbo 8v application with a deeper bowl, but I had them decked to reduce the bowl size and then the block skimmed down to match and bring the piston proud of the deck face to give my favoured squish...
It need a fair bit off....80 tho...yep..2mm!....but it took it ok much to the surprise of my machinist...
Some more ARP hardware is used to hold the head in place in the shape of their high quality stud & nut kit...
Nothing gets taken for granted in the JMR workshop, even new parts get stripped and checked...
...with the bottom end all closed off with a JMR baffled sump...
The head was built up with steel buckets & shims, along with some cam lobe clearance to stop the Kent GS6 cam we used clattering into the head!...
The internal hardware consists of Supertech valves, valve springs & top caps, and just to prove this is the "small valve" version...
It's difficult to know exactly how to describe it as it's running std valve sizes as per a GTi @ 40mm inlet & 33mm exhaust, but the crossflow comes with 39.5mm inlets in std form, so we use Supertech's 0.5mm oversize inlet which fits on the std seat ones cut to suit...so it's sort of a big inlet valve conversion but at the std GTi size we all know. The head flow's 94cfm on the inlet, which is around 8cfm more than I see from a std 40mm inlet in a conventional GTi head, and around the same as I see from a 40.5mm inlet in a conventional head...Jon Wool's & Tony B's original head both make/made 94-95cfm from a 40.5 inlet....so the crossflow head works better in that form.
Feeding the air into the head are a pair of Jenvey's finest in 45mm flavour, mounted on one of our JMR inlet manifolds which was prototyped on this engine...
...and the waste gasses exit via Tony B's old Ashley 4-1....nothing trick (yet!), but it works...
Tim supplied the trigger wheel already mounted on the front pulley so I made one of my sensor brackets to suit, and we gave it all a stir on the AP Motorsport dyno......but did we hit "our" 200hp target....
....not quite.....197hp @ 6,500 rpm, with a drop of to 194 @ 7000. Peak torque is very strong though with 162ib/ft @ 5000, which is 20-25ib/ft up on what I see from the top spec 1800 8v hillclimb engines...and they're far from slow!
When I say "our"...Tim had his fingers crossed for hitting 200 but I didn't calculate it as possible on the small valve head as I knew it would cap the torque back at the very top end and expected around 194-195, but it's still pretty good for a restricted 2ltr, and in all honesty as Tim has to run to a power to weight limit in the VAG trophy it gave a touch over what we needed for the cars weight so he'll need to carry a couple of kilo's ballast to start with to give the turbo boys a chance!....until we change to the proper big valve head over the winter that is!
After a few installation teething troubles Tim had a great run coming up through the field at Snetterton recently only for 5th gear to shred itself 2 laps into the first race of the weekend!....roll on Brands Hatch in a couple of weeks...I'll be watching from the sidelines so fingers crossed!