Re: Fiat X1/9 twin cam turbo
Gordon and I have been discussing the specifications of the racerX as we go about getting the twin cam mounted into the chassis. So far the installation has been easy, as we are using the mountings I made for my Xroad car (which is awaiting paint, and not being used at the moment).
We fitted the dummy engine/gearbox into the car after cutting the left hand chassis to clear the gearbox, and took some pictures. Gear linkage was a bit more troublesome, as the springy feeling, which I thought was being caused by movement of the engine/transmission, was still there after mounting the engine more stiffly…. I traced it to the way I have made the linkage for the forward/backwards plane, so a redesign is underway, and I’ll have some pics of mk2 in a couple of weeks…. (the part of the shifter mechanism that handles the left/right movement of the gear lever works just fine )
Currently engine specs are still to be finalised, but he basics are:
Turbocharged 8V 2000. (Conventional flow) Lancia block, machined to accept 12mm x 1.25 bolts, Copper head gasket, Forged pistons with dished crown (bowl volume/shape to be determined) static c/r 7.5:1, Fiat con rods modified to accept Chevrolet small journal big end bearings (as there are superior material types available compared to what is available for Fiat journal sizes), crankshaft cut down to 14kg (from around 16.5). I want to use a very light flywheel, the clutch will need to be a true racing triple plate item. Oiling by (baffled) wet sump, remote oil filter, oil cooler, fresh oil return to main oil gallery (on exhaust side of engine). Head configuration (ports/valves) and cams are still undecided.
Turbo will likely be a T04B, sized as per my Dad ran on his turbo race cars, which is pretty huge, the turbine housing on the Uno is stamped 1.52, and run a separate (cockpit adjustable) external waste-gate.
I’ve been doing a bit of research on turbo exhaust manifolding recently, checking out several different Fiat/Lancia standard turbo exhaust manifolds (Thema8v/Integrale8V/Integrale16V) as well as several that my dad made for his UnoT and his 131 Abarth. It seems there is another entire branch of “black” science with this part of the setup…..
I’m still undecided on the final design, as often it seems that what looks great doesn’t work very well, (as in the amount and timing of boost) but am leaning towards a split entry turbine housing and routing the piping from cylinders 1 and 4 to one side and 2 and 3 to the other…. The successful exhaust manifold designs (especially for serious boost applications) I have seen pay careful attention to minimising the amount of reversion that can occur between cylinders by keeping the exhaust flowing towards the turbo, so separating the pulses by 180 degrees should ensure that one cylinder has finished it cycle before its opposite number gets to open its exhaust valve.
Most likely we will start with a draw thru system, but instead of a carburettor like my dad’s setup, we will use a single (two barrel 45mm) FI throttle body mounted ahead of the turbo. With injection we can have far more precise control of the fuel supply to the engine, and if we get a throttle body that can also be used in blow thru application, then we can eventually shift the injection to the other side of the compressor and run twin throttle bodies atop a std Fiat down draft manifold. No inter-cooling is planned to begin with.
Along with the improvements to the power-plant, there also improvements planned for the brakes and suspension.
Currently with the brakes the thinking is 284 x 22mm (46403088) vented discs at the front (from a Fiat/Alfa) and calipers/pads from the Fiat20v coupe (4spot Brembos).We can get these discs locally (in Australia)for $145 each and have them slotted for another $20
At the rear would be 257 x 20 vented discs from Lancia Integrale/Fiat Croma turbo (82433860) with Fiat Uno turbo front calipers/pads at the rear. I have a few discs already, but these can also be found locally for around $125 each
The car already has stainless braided flexible brake lines, Tilton inline bias valve (in rear circuit), and tandem brake master cylinders (3/4” bore currently but we have a pair of 7/8” bore m/cylinders if needed) with adjustable balance bar (ala PBS X19 book)
We are also getting into reducing the weight of the chassis some more, as most of the other improvements also increase the weight of the vehicle. I popped the gearboxes on the scales over the weekend, an X1/9 4 speed gearbox is 30kg, the Lancia 5 speed is 50kg …. So that’s 20kg’s in just that one component.
I suggested getting rid of the tunnel and water pipes from under the car, to save some weight, increase our ground clearance, and make the floor more flat. Gordon was happy to pass me the angle grinder but I left that job for next time, its high on the list.
We will re route the cooling pipes through the cabin, maybe even getting some made in aluminium tubing, we also plan to duct the hot air out of the radiator thru the bonnet, rather than under the car.
Gordon has already removed sections of the floor on the RH side, leaving the chassis sections, but removing the steel floor, which will be replaced with aluminium sheet. Long term, we plan to make the underside of the car very flat, to try and maximise the X19’s aerodynamics.
Also on the drawing board is a change to much larger wheels and tyres. Gordon already has some 16 x 7 rims, (for wets) and wants to get the rims that were on the racing UnoT when it ran slick tyres, some very nice Simmons 16 x 9’s! We are also planning on repositioning the suspension mounting points to ensure the lower control arms are absolutely level to the ground (front and rear), not radically (as in the X19 PBS book), as I’m figuring the change needed at less than 12mm (1/2inch).
I'll be back in Perth in a couple of weeks for the next round of work, more pics to come
SteveC
www.x19.nu
