warps

What? a turbo piston engine was faster than a NA rotary? Stop the Press!!! You and I both know that the IPRA restrictors hardly strangle a 1.8 litre engine. What they may lose in top end they will more than make up with a fatter torque curve. I certainly won't start one of those arguments here.What about other tracks? What about race results? All those RX7's out there must be running piston engines as well then, hey? Yeah, yeah, more sour grapes. It's all a conspiracy

Pure gold!!

No need for personal attacks. This is all in good fun.

Ah, Gary's just upset that the rotaries are dominating IPRA Better tell CAMS that their rotary multiplication factor or 1.8 is wrong. You can buy Renesis engines for light aircraft, and from all accounts they work pretty well, too. They run them through a step down gearbox to get the prop speed into the correct range. Why don't they just make a few slight mods to the rotary and have the rotors direct coupled to the crank, the way they always should have been? Makes sense as it could remove two potential failure points. Highly important in an aircraft I would think

I'll see your permanently on heater (not because the rad can't cool, but because the tap is permanently on) and raise you one glowing exhaust system next to my leg. The rotary exhaust runs so hot I can smell paint on the trans tunnel burning at the end of each stage. Even the handbrake handle gets too hot to touch. Not such a bad thing in winter, but it gets awful hot in summer (Gallangowan 2008 was a shocker. Even the water out of my camel back drink bottle was coming out hot enough to make a cup of tea) But yeah - hot and sweaty is so much fun. Lucky I'm such a hard bastard Dedicated track car - yeh I'd probably strip the A/C out if it wasn't working well. Anything else and I'd happily leave it in there.

Yeh probably not. I'm not used to this black sticky stuff where going sideways actually costs you time Still, even allowing for a bit of inconsistency, it shows that the power loss from A/C on hardly has a huge impact on lap times. Just for the record, my times on the day were 4th fastest outright, beaten only by two very modified GTR's on slicks or semi's, and the same model WRX as mine but with about 400HP and mega dollar suspension work. Mine was bog stock, still with spare tyre and kiddy seats in the back. I must've been doing something right.

Haha no need to sugar coat it - yes I have grown soft in my old age and am very proud to admit it. What happened was, as I was sitting at the start, I had the air conditioning on (was a hot day, wearing long sleeves and jeans, black interior yadda yadda). Yes - I like to keep cool while I sit at the staging area. When my session started, I forgot to turn off the a/c, like I normally do once I hit the track. That was my point - the one time I forgot to turn off the A/C was the session that I recorded my PB out there. Obviously the A/C coultn't have affected my performance too much. It might be soft to try and keep comfortable, but when you eliminate one source of potential brain fade (specially in long rallies in the middle of summer) I'm more than happy to be called soft. Track days on the other hand, well yeh no need to leave it on while you're out there racing.

As far as weight saving goes, 10kg is hardly a deal breaker. As far as performance goes, well consider this: My PB at Morgan Park was set when I forgot to turn off the a/c on my second last run of the day. This was an otherwise stock WRX. So much for the a/c sapping performance. Consider also the benefit off having a cool cabin when you're lapping on hot days. With the rest of the interior stripped out, the interior can get extremely hot on a warm sunny day. The effect of having a cool, alert driver will do much more for your lap times than stripping 10kg of dead weight out of your car. My next rally car is going to have the A/C left in. Specially good for de fogging on those rainy night time stages.

mmmmmm....burritos </homer>

People don't underdrive pulleys for the power gains (although there is a very slight gain, since power = force x speed, and you're reducing the line speed of the belt). The main reaso they do it is if the engine lives at high RPM, to protect the alt and keep the water pump in the efficient range. Excessive RPM will caviatate a water pump - not a good thing (means it's trying to pump air instead of water)!! If you plan to race the car, by all means use an underdrive crank pulley for those reasons. You WILL get some free horsepower, but I doubt anyone this side of Michael Schumaker would notice it. If it's just a street engine - probably not worth the effort. Do NOT change your multi vee belt for a single vee. You might as well swap your RB engine for a pushrod 202 if that's the case - big step back in technology. (less slip and far more resistant to being turned inside out at high RPM). If you've ever raced a rotary, you'll know the heartache of throwing fan belts at high RPM. Multi Vee belts do not do this. Lastly - reduced rotating mass (eg lighter pulleys) do NOT give more power. That is a fallacy!! At best, they will make the engine free rev quicker. I'm not a fan of EWP's (have heard horror stories from people who have spent many years in racing circles). Each to their own through, as I know a lot of people use them happily in racing. I won't try and force my opinion on that topic onto others.

I'm curious to see how you work out the spring rates, Gary. I have a spreadsheet (derived from my engineering text books many years ago) which I use successfully, and it gives me much lower values than what you're quoting. Also, I note a few people have given you the spring OD, rather than the ID. Not having a go at all. Yes, the formula is complex to the layman, but there aren't a lot of variables that can change. The modulus of rigidity is the only variable that can change, and that is pretty constant for carbon steels and alloy steels (although Stainless is different, but I don't think many of us use stainless springs, do we?) I've just checked my calcs on two springs i have here, whose rates I know (from catalogues and shop manuals) and my calcs were very close with both of them (in fact my numbers were a bit on the high side if anything) Also, I haven't read the ful 18 pages of this thread, but you should use the number of ACTIVE turns of the spring, not the total number of turns. That is, the number of turns that aren't in contact with the spring seat, as the metal in contact with the spring seat doesn't actually do anthing. Again, not having a go at all, just interested to hear some real world experience. I'm happy to take this to PM, as I'm not one to try and jeopardise your business. So you know I'm not just another internet hack, I'm a qualified mechanical engineer, with over 20 years experience and run my own consulting company. No, I don't design or make springs for a living, but have had to do several spring calculations to confimrm the correct operation of products I've been involved with over the years (most recently a major claim against a manufacturer who supplied some spring operated brakes that weren't performing to spec)

That's probabbly coz there's less risk with the bank if they have something in writing that can be traced back to the card owner. A phone conversation leaves no paper trail. When we first set up our retail shop, the banks wouldn't let us take credit card payment from customers over the phone. Too much risk for an unknown business they told us. I could see their point, and was happy to go that way, as it offered us some protection too. Now, onto Von Bibra Nissan. they've serviced my pathfinder for he last 2 and a bit years. I've had a few warranty claims in that time (auto dimming mirror that didn't, climate control aircon that made funny clicking noises under the dash, rear cup holders that came apart). All have been replaced under warranty, no qns asked (and these parts aren't cheap to replace, either). We've had some concerns about the quality of their admin staff, but the quality and level of service have been fine. I can say that the service has been better than what we get from Subaru. When I had my import Skyline back in 2001, I took it to my local Nissan dealer for the blue slip (Singleton, NSW). Agian, I had dealt with them a bit through owning Nissans and Fords in the past, and they supported me where they could. they didnt exactly go out of their way to accommodate me, but they were never rude about it, and when it was something tricky, they apologised and said that they don't have the ability to support that particular request. Mine was the only import in town at the time. Whether that was a good or bad thing, I don't know. I always get my cars serviced by the dealership. Less chance of any warranty complications that way - I won't get into legal battles with them. Might cost me more, but my business pays for it, and besides, I charge vehicle use at $1 per km to my clients anyway, so my cars make money for me Still, I don't think they'd look too kindly upon me rocking up at site in a new GTR

"as straight as possible" I think would be the idea. The cage diagonal members (and in fact most members in a well built cage) are going to be loaded in compression. this gives the whole cage its strength, making it act as a rigid structure, rather than a bunch of pipes glued together. A well designed cage should not have to withstand bending forces in any members as there is very minimal strength this way. (I'm talking about the rigidity of the whole cage - not individual members). Now, a steel pipe is very strong in compression, but as soon as you put any eccentricity into it, ie a bend, it loses a massive amount of its buckling strength. Hence the straighter you can keep any compression members, the stronger they will be - lots stronger. There is a formula for calculating the loss in strength due to eccentricity (Euler column buckling strength - might find some info if you google it) but I'm to lazy to do manual calculations these days Ideally, every member will be straight. In reality, we don't always have that luxury. Just a little back ground for anyone not fully conversant with cage design and failure modes. Sorry if it's a little simplistic to those already experienced in cage design.

Read my comments above re: turbo RWD rally cars. a well sorted FWD rally car (such as Sunny GTI) will snot on most RWD cars every time. For speed, FWD > RWD on gravel - can't argue that. As I said in my very first posts, I like the thought of a turbo RWD Nissan, which is why I am considering it. Nothing more. I know I wont set the world on fire, but I will have a bucket load of fun. Sometimes our choices aren't based on what's good for the sport, or what will progress our motorsport careers. My choices are about getting a more balanced, reliable car that I can have the most fun in (BTW Sprinters have excellent balance too, which helps to overcome their lack of power). Nothing else really matters to me. My other option at this point in my life is to chuck it all in and learn to fly instead. I'm having a very hard time making that decision.

That's what I'm talking 'bout!!! (must've left the Prince of Darkness electrics in there though

/Has anyone tried MCA (Murray Coote) on track? they're the ducks nuts for gravel rally, but I haven't heard of too many people using them for circuit only cars. Not to say it hasn't been done. I think they're around $2k per corner. Good comment about playing around with the factory settings. Too many people can't resist the urge to fiddle. Not too many people can tell when they've got it right just from seat of the pants driving (I put myself firmly into the majority there). Nothing at all wrong with a well sorted bilstein setup, either. Have heard of a few people having trouble with DMS - cracking etc. Again, this is gravel rally cars that pound the suspension pretty hard. From what I gther, most of the problems occur with people under sizing the DMS (going 50mm on large cars when 60 is better suited, etc.)

Following is an extract from the CAMS manual regarding turbo restrictors on rally cars. Turbocharger Sealing Requirements 1. For all turbocharged Group N and Group N (P) 4WD vehicles , whose homologated turbocharger inlet size is 32mm or greater (22.6mm for vehicles fitted with two or more turbochargers), and for all turbocharged Production Rally Cars (PRC), whose turbocharger inlet size is greater than 34mm (24mm for vehicles fitted with two or more turbo-chargers), it will be compulsory to have a restrictor fitted in accordance with FIA Group N Regulations, Article 6, save that the size of the restrictor for PRC will be 34mm (24mm for vehicles fitted with two or more turbochargers). 2. These Regulations do not apply to two-wheel drive turbocharged vehicles. However, competitors with 2WD turbocharged vehicles must attend turbo scrutiny and must be checked for inlet size against the homologation papers and have the compressor housing sealed to the bearing housing. For those competitors with non-homologated 2WD turbo vehicles, components must be identical to the series part. 3. The turbocharger restrictor will be measured and sealed in place prior to competition in any round of the Championship. All turbochargers used on these cars during the event will be required to be measured and sealed prior to their use. 4. Competitors must present turbochargers to the organisers in a condition to be sealed, ie, they must be wired and prepared for sealing with leadseals or a CAMS-approved alternative in a manner that will be easily seen when assembled on the car. The restrictor must be sealed to the compressor housing, which in turn must be sealed to the bearing housing which in turn must be sealed to the exhaust housing. This can usually be effected by one wire and therefore one seal. The diagrams below may assist. Here is a link to the full paper on turbo sealing and restrictors for gP N and PRC rally cars. (go to page 3)

Correct. The GTR is considered AWD under PRC rules, so must have a restrictor on each turbo. The restrictors are sized for 2.0L turbo engines to peak out at about 300hp, but the top cars make bags of torque. The 2.6L GTR engine will struggle with the same restrictors, and probably make LESS power than stock. This rule does not apply to 2WD rally cars (the theory is that they cant get the power to the ground anyway - which has a lot of truth to it). Talking to owners of turbo RWD rally cars (DR30, BLuebird, Silvia, FC RX7, FD RX7) the consensus seems to be that the stock turbo running stock boost goves the most enjouable drive in the gravel. I have silimar issues with my RX2. Plenty of power (180RWHP) and no traction makes it "interesting" to drive in the forest. I prefer the fat torque curve of stock turbos for gravel rallying. A mechanically stock GTS2 or Silvia (with some uprated springs and shocks ) will be very competitive against some big dollar Escorts, Dattos etc. and be a lot more reliable and easier to live with. It's a logical choice. I don't think that the S13 and S14 owners have had any trouble fitting 15" rims onto their cars. In fact, the S13 rims are available just about at every newsagent, so makes them perfect for rallying. ou can have 3 or 4 sets of rims for a few hundred $$. doesn't matter if ypu bend some rims.

Good move, Marlin. I was feeling a bit guilty about the serious hijack I currently rally an RX2 which is great fun, but getting frustrating due to the lack of parts available. An R32 Skyline or S13 Silvia are both excellent rally choices, due to the availability of spares and their inherent balance / performance out of the box. There are a few S13's rallying now, and I know of several others in the build, or about to start being built. I think they will likely become the 1600 of the 21st century (although their body strength is yet to be determined - just can't kill those 1600's without hitting it with a big fkoff tree.) I have spoken to CAMS anout eligibility of the R32, and by the book the GTR is the only one you can run as a PRC car. However, most of the events I compete in ahve an "all comers" section where cars are allowed to run that don't normally fit in the PRC guidelines. That's fine for me as I have no interest in winning championships. Most of the club rallies I've done have central servicing, so you don't need a service crew. Tou just front up with yoour tow vehicle full of tools, and service is done at the same place. The events are usually one or 2 days too, and most people camp out overnight. We choose to camp, but I know a lot of people who drive to the event in the morning, compete, then drive home afterwards. Makes for a long day, but we've done it several times. If you want to chase ARC points, then it takes some more commitment, and $$, but that's no different to running at the top level of any motorsport category. If rallying takes too much organising, then there are sprints, khanacrosses etc that let you fang around a gravel track all day, and you don't need so much as a spanner man. you can turn up by yourself, (no navigator needed) and do all your own running repairs, although there are usually plenty of others offering to give you a hand When I sell the RX2, my preference is to build an R32 GTSt. DOn't waste your time with NA - a decent L20 Datto 1600 will rung rings around you as it's about 300kg lighter, and not a lot less powerful. The minimum weight for a 2L turbo RWD rally car is 1270kg, so it makes no difference whether you build a Silvia or R32 Skyline. I think either would reach that weight without too much drama.

Excellen

I've tried searching, but all the posts seem to be about what's the biggest wheel I can fit on my Skyline? I'm going the other way, and am wondering whether there's a commonly available 15" wheel that will clear the standard R32 GTS-t brakes?

Not quite. Taken from the CAMS manual: The fitment of a restrictor for turbocharged cars, in accordance with FIA Group A Regulation 5.1.8.3 is compulsory for all four-wheel drive cars and is optional for two-wheel drive cars You mean R32? Still a consideration, though I prefer turbo torque in this instance. Harry - while it doesn't state that the 180/Sileighty are eligible, that seems to be the consensus among those far more educated than myself. I haven't spoken to CAMS in detail about this yet. I need to find out more about what the eligibility means. Does it mean I can't logbook the car, or it won't be able to compete, or it won't be eligible for points? If it were the latter, I wouldn't give a stuff, since I'm only doing it so I can legally drive sideways in the forest. If I cared at all about winning, I;d be investing in an Evo or WRX (there are some top notch AWD gravel cars for sale for less than what it would probably cost to build a good Silvia / Skyline). I know there are many rally cars out there that don't fit into PRC, but still get a run (as Schedule R I believe). I need to find out more about the classes to make sure I don't snooker myself. I heard that you have a Silvia. If it's anything like your other cars, it might be a bit of a handful in the dirt . Mind you, I'd be more than happy to try it out for you.

The Sileighty is exactly what I was looking at - easier to fit a cage in there, and better lighting setup. Yes - all variants of the S13 are homologated. There are minimum weight limits for gravel rally cars (1260kg), which you would easily achieve with either in stripped out form. I originally looked at a Silvia, but it seems everywhere I turn, somebody is building one. within 4 years they will be like the 1600 was 15 years ago. I wanted to be different, but might have left my run a bit late. I also agree on the Skyline. I wouldn't do the GTR, but rather the GTSt - no need for turbo restrictors that way (would kill a GTR performance). Still lots of rock throwing goodness. I reckon a stripped out, well caged R32 would still come down to the minimum weight limit and be a barrel of fun. Most club events don't care whether your car is homologated or not, so that's not really a big issue. I downgraded my CAMS licence this year from RN, so wasn't planning on doing anything higher than club events anyway. As youo say - I may not be fast (have you seen me drive?) but at least I will have fun and put on a good show. Just need to find a set of 15's that fit over the Skyline brakes. Edit - I see you are in Brisbane. I'll have to come and check out your race machine some day.

Great write-up Risking. This is especially interesting as I am contemplating a 180SX build for my next gravel rally car, and will be putting in the most comprehensive cage I can fit in there. Rather spend $$ on a good cage than making it go fast. Good cage and a set of MCA's will probably do me (with the necessary seats, harnesses, instrumentation etc). Engine and driveline will probably wait till I feel the cars holding me back, rather than the other way around. Just a heads up on notching - those notchers are a good bit of kit, but we;ve never bothered with them in the past. We find that cutting the pipe ends with a drop saw gives the same effect when done correctly, with the added benefit of bevelled joints that don't need prepping. yes, I'm anal and like to prep all my weld joints. Probably not really needed, but I find it gives a good result and makes more sense to me. Also agree with cutting the holes in the floor. By the time you re-plate them, and then box the mounts you haven't given anything away in strength. I've seen too many dodgy cages with only half welded joints (which, BTW are often still plenty strong, but again I prefer to make it as strong as possible). Will be watching this one with interest. Good for tips on what to look for when I get around to building my next car.

Not only that, but if you have ANY accident while towing the trailer, the indurance company wont pay as they can say that this contributed to - or caused - the accident.