GT-Four Model Variation - ST185 Rally Champ
(AKA Carlos Sainz, Group A Rallye)
The ST185RC was a limited edition homologation model. FIA regulations at the time required 5000 cars to be manufactured to allow the model to be used in rallying. Numerous aspects of the normal ST185 design meant some changes were required to provide the necessary durability for rallying. These changes were a direct result of Team Toyota Europe's input.
The ST185RC is visually different to the normal model in that it has a different bonnet and bumper. Instead of the scoop the bonnet has an air vent (to expel hot air) and a small round scoop to provide cooling air to the cambelt housing (found to melt during rallying on older models). At the rear are two additional rear facing exits. The bumper is more bulbous and has a larger vent area. Also the large heavy steel bumper is missing, a petite aluminium extrusion taking its place. As a result of these changes the cooling efficiency (resulting from increased throughput of air) is much higher. All ST185RC models were the widebody version with the 15" wheels. The rear bumper was also redesigned to reduce weight.
The engine differs from the normal car in that it uses water-air intercooling. The intercooler is about twice the size of the ST165 one. Unfortunately due to the large area of the IC the seam is known to pop following boost spikes (as in 30psi+). The TTE ones had vertical stiffening struts and extra cooling rows installed. The RC also uses a different turbo and air flow meter. The ECU has the fuel cut at 17psi, up from the normal 12psi.
Otherwise the engine has no significant changes over the normal ST185.
Other minor changes include different suspension settings and a lightweight, low restriction exhaust system.
The Japanese model had 235 PS (~230bhp), which I assume is the result of high octane fuel and aggressive timing. The export models only had 205 - 210bhp, and less torque. I guess they were detuned, but this engine still has more tuning potential (IMHO) than the normal ST185.
The RC was also fitted with a new gearbox, the E151F (although this was also fitted to later models). This gearbox has triple cone synchros on second and dual cone on third to help reduce the synchro graunch problems all Toyotas suffer from. It also has two synchro rings on fifth, Teflon coated shift forks and several other improvements. It came with the 3.933 diff ratio, so if top speed is not an issue converting to the 4.285 ratio is one of the best mods you can do. BTW, this gearbox bolts straight into any ST165 or ST185.
All in all well worth paying the extra to obtain (if you can find one!).
Here is a copy of the original 1992 press release for this model. Note that this is not the original format and thanks to the person that posted it a couple of years ago.
|A Japan spec GT-Four RC. The Japanese cars had the normal GT-Four markings, but with red RC labels added. The wide body is clearly apparent in this photo.||Cut away of the water-air intercooled ST185 engine.|
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