by Alby » Sun Jan 30, 2005 6:28 am
Hi Alpiniste,
here goes with some info about A310 / 4 cylinders as discussed previously.
Information available - English: Not much!
Reference book "Rally Cars" by Reinhard Klein has a page on each of the 4 and V6 310s. Unfortunately perpetuates the myth that the main problem with the 4 cylinders was that they were too heavy at 100kg more than the 110. Mauro Bianchi who had a big hand in their development says they were faster than the 110 anyway.
Road Tests - quite a few in english classic mags over the years but nearly all the V6. Most english tests not all that complimentary, but Australian and US ones all tended to rave about the V6. Test in Nov 2000 Classic Cars (thoroughbred & classic) c/w a Porsche 911 is about the most accurate I have seen and I've owned identical models to both used in that test.
Only one that covers the 4 is Nov 84 Classic and Sportscars - gives direct and accurate description of the driving differences between the V6 and the 4. Brooklands Books "Renault Alpine Gold Portfolio 1958-1994" has this test and many others of the 4 and all other Alpines up to the 610 - a great guide to Alpines generally.
French info - more available if you can make your way through French text with help of the pictures.
Great reference book on all Alpines - "Alpine Label Bleu" by Christian Descombes. Model and competition history.
"Alpine" by Dominique Pascal is also great for 110's and 310" but seems to have been out of print for some time. Much more competition detail.
"Mille Miles" alpine magazines has had a number of good articles and they are available on back order over their web site - issues worth getting for 4 cylinder info include no. 10 ( very comprehensive article about their design, production, etc & a great editorial by Mauro Bianchi), No 22 (article about a 310/4 restored and modified for historic rallies such as Monte Carlo) and no 32 ( article about an original competition 310/4 1800, now restored for historic rallies).
Weight
Standard car weighs 840kg's. Pretty easy to knock off about 50-60 Kg"s without ruining car. After that it gets harder.
Interior - rear seats and miscellaneous trim items, radio & speakers. replace eletric window mechanisms with windup - 16kg's. Replace front seats with competition buckets - 14kg's.
Front - remove front rubber bumper strip (2kg's), lightweight battery (8kg's), remove heater and all hoses (5kg's?).
Rear - remove rear bumper strip (2kg's), remove engine cover and replace glass with louvres (7Kg), replace air cleaner with sock or alternative (3kg's).
Suspension
These cars handle so well there may not be much room for improvement. Standard springs are relatively stiffer than on V6 and there are less rubber bushes (which is why the V6 is a better road car). I am going to start by keeping the standard springs and just replacing the shockers with adjustable rally spec koni's and with adjustable spring platforms to lower the car about 1 inch all round. Will let you know if I think it needs more.
Wheels
Standard wheels are 6.5 x 13 and are very light. Could run these quite successfully with 195/60 on front and 205/60 on rear. I have gone to 7x15 with 205/50 on front and 8x15 with225/50 on rear. With different offsets these would fit under standard guards but I have gone for more width with early look group 4 guards. Why, because ever since I first saw photo's of 310/4's in tarmac spec I have loved how they looked and wanted to do the same! Whether they are any advantage or not, who knows? By the way, standard wheels have 140mm pcd and other wheels that will fit are almost impossible to find. May be possible to change hubs to take 100 pcd wheels - I am looking into this.
Brakes
Standard is ventilated discs at front and solid disc at rear. All around 156mm from memory. On a light car, these may be fine with the right pads, braided lines, racing fluid and air ducting to the front. I am making all these mods but also planning to replace discs with 173mm peugeot 505 discs (vented front, solid rears) which I am told will bolt straight on. Am really only doing this because its easy and the greater leverage should help - brakes are unassisted on most but some cars have boosters. If keeping standard wheels, there is no room for larger discs.
Steering
At 2.5 turns lock to lock its great and has terrific feel - don't change.
Gearbox/diff.
All had 5 speed close ratio boxes. Speeds (in km's per hour) in gears at 7000 rpm with 225/50 x 15 tyres are 68, 105, 152, 202 & 237. Changing up at between 6500 rpm and 7000 rpm always brings you into the next gear at 4,500 plus and over 5000 rpm in the high gears, so ratios are fine.
Diff ratio is a problem. Its 3.27 to 1 standard and whilst this is fine for the road its too high for competition. Most Australian race tracks and tarmac rallies, you don't get to much over 200, so you never use 5th gear - a total waste. By the way the V6 is even worse in this respect as 4th goes to 220 at 7000 revs. Originally, the cars were available with an optional 3.77 diff and this would be perfect, bringing 5th down to almost where 4th is now. However, I have tried everywhere I know to find one without success. I have just gone through the exercise of pulling my gearbox out to look at the diff, and then pulling apart a number of other Renault boxes to see if their diff's might fit or be made to fit. No luck. Now going through the frustrating exercise of putting it all back together.
Engine
Early models were the same engine as in 110's with twin 45dcoe webers. Late models still the same but with djetronic fuel injection. Arguments for and against both, so its whichever meets personal preferences.
Engine is 1605cc standard and had 125 hp. (often quoted at 140, but thats to the old sae standard) You have plenty of people in England who have tons of experience with these engines and may be able to assist with diff's as well. In brief, normal mods can include bigger pistons and liners to 1774cc or 1860cc - both require some block machining, bigger cams, compression etc. Done fully, but still reliable, around 160hp should be comfortable.
Our rules require use of pump fuel, maximium 98 octane, so building a big cam, high compression, revy engine is more limited. Maximum practical compression is about 10.5 (standard is 10.25). We are therefore going down a different route that is somewhat experimental and aims to maximise torque which is important for our tarmac rallies which are all in hilly country. We're using 82.5mm pistons and sleeves which would normally give 1795cc's, but also stroking the crank to end up with 1995cc's. Stroker cranks were tried and dropped in the 70's possibly because everyone was after higher revs, max power then. We think it will be right for our needs and my engine builder is using a few secrets which he says will make a good difference and he won't even tell me what they are!
Anyway, with this size, a fair bit of head work, standard gordini spec cam, individual throttle bodies and Wolf 3d engine management I'm hoping to end up with over 160hp in an engine my granny could drive to the shops.
For tarmac rallies, I'll keep the throttle bodies but go back to the original djetronic management system. This is a rule requirement but I don't think I'll lose much by it as there is tons of info on the web on how to modify these systems to suit modified engines. If it doesn't work, then simply back to webers for those events.
By the way, these engines had a number of benefits compared with standard Renault versions or the version used by Lotus in the Europa. Besides the cross flow head, important changes were cam, valve sizes, extractors, better con rods, heavy duty oil pump.
Cooling
Standard radiator in good nick should be fine but I've replaced mine with a thicker alloy unit as a matter of course. Using twin thermo fans with an over-ride switch. Cars come standard with an oil cooler. Gets very hot in the engine compartment. I'm having the extractors treated witth the stuff that keeps them cooler (can't remember the name offhand) and the louvres will undoubtably help with letting hot air out.
That's about it. Hope the above is helpful.
(guess I didn't make it clear...)
