Ade

The stock pressure switch is at the outlet of the oil pump. The oil galley at the top of the engine next to the oil filter is the feed to the crank. I haven't tested it myself yet but it looks like it reads lower which makes sense...

That not nessessarily true. Hotter oil = lower pressure. Is anyone paying attention to Oil pressure? If you dont have enough oil pressure in the crank bearings with these turbo'd/Supercahrged cars you can kiss goodbye to them..... Adding an oil cooler might cooler the oil but the extra flow may reduce pressure further. From what I ahve seen over on the ft86club people are getting 42-54PSI @ 7kRPM @ 116C oil temp. If you are one of those 10PSI per 1KRPM people this should worry you! The car bone stock had 52-55 PSI at the same oil temperature..... I am going to fit a Defi Oil pressure guage and do some proper testing.I'll report back....

I'd never consider a GTR personally. Its far too heavy! Rather a Lotus Evora or something along those lines.... I think Lauren hit the nail on the head. THe GT86 really shows how good it is whe nyou push the car to the limit and put many a hyper cars to shame in terms of feel and fun factor. Just have a read of last year Top Gear Speed week. They found the gt86 more fun than the likes of the porsches..... Autocar had the GT86 as "best handling car 2012" ahead of the Porsche Cayman S and Lotus Exige!!

The GT86 clearly wasnt designed to work at 80C. Cruising on the motorway you will observe 105C on a stock car. I went for a hoon today. 14C ambient and managed to pull 128C peak oil temp. I do thrash the car more than most though. As far as I can tell the Subaru forester FA20DIT oil cooler is the best option. It warms the oil up quicker but cools it a bit when it gets hot. Importantly it doesn let the oil drop much below 100C in the winter. Win Win and Win. All I need to see now is that it doesnt affect oil pressures and I will be fitting one....

Yep. The quote from Steve about is from that thread where I read about it.

The sprintex is a great kit, nice flat torque curve and i'm not trying to knock it, but as far as I understand with the 69mm pulley at ~7500RPM, the sprintex 210 at more or less at it maximum rated RPM. Sure you can overspin the Sprintex but Im talknig about using them within their rated RPMs. Yes I said 75mm in my post but its only slightly bigger than 69mm! 10% RPM margin is not a bad idea! THe HKS, for example, is like 230hub but unrestricted will do +100hp on that. Maz's car has a slighly bigger restirctor than the base kit. The sprintex is also great bang for the buck. Liek I said they all have pros and cons

So Maz's car is at about the limit? I believe he has the restrictor that comes with the injector upgrades.

I think the sprintex is a great kit but they all have their pros and Cons. I would assume some of the lower end torque on the HKS comes from the fact that it is being restricted so yes if you make the restrictor bigger i'd only expect to see and increase in the top end power. What you are saying is true but you can bore out the restrictor plate for free where as a new turbo will cost money and the Sprintex is already at full chat with the 75mm pulley. The HKS does cost £4.2k though....

The manifold may help but the HKS still has a restrictor which can be bored out a little (or removed - not on a stock engine though) to give more power. Not sure on the limits of the stock injectors.... 300Hub?

I didnt say I believed it!!! THough the GT86 was their car of the year! My response to top gears comment let see how many car of the year award the Mustang wins.....

Top gear first drive: http://www.topgear.com/uk/car-news/new-ford-mustang-first-drive-car-review-top-gear-2014-09-17 and I quote "Give me more of an idea here. Would the EcoBoost Stang give a GT86 a run for its money?" It wouldn't just give it a run, it would smash its face in. The new Stang has a stack more grip, more power, more torque and is an altogether bigger, faster car.

Hi Keith, Basically motion ration is the ration of wheel movement to spring movement. For the front of the GT86 it is almost 1:1 because the strut is connected to the wheel hub. On the back, the gt86 has a double wishbone setup whereby if the wheel moves 100mm, the spring moves 75mm making a 0.75:1 motion ration. This has the effect of lowering the effective force at the wheel relative to spring rate and this is the reason why the rear spring appears much firmer than the front. Wheel frequency is the natural frequency of the mass (the car corner weight) and the spring rate when it hits a bump (impulse if you like). Generally you want front and back fairly close together for a stable car. Some of the coilover kits really worry me in this respect with spring s50% firmer at the front than back, which translates to a wheel frequency's very unmatched. Square spring rates seem to be favored by most high end manufacturers, such as Ohlins.

thats hot! are repeat +70C IAT really not going to shorten the life of the engine?

Special K, its to do with the motion ratio which affect the actual wheel spring rate. The relationship of motion ratio vs wheel rate is: Wheel rate * (motion ratio)^2 So for the front its 1.1:1 being a strut so the wheel rate is 2.3*(1.1^2)=2.8kg The rear has a motion ratio of 0.75:1 so 3.7kg*(0.75^2) = 2.1kg So effectively the force on the wheel is 2.8kg/mm front and 2.1kg/mm rear on the stock car (gt86 - the BRZ is slightly softer at the rear) If you consider the car has a 56%/44% F/R weight distribution, you can work out the wheel frequency which come out around 1.4Hz back and front, so the car is very well balanced in stock form..... Once you lower the car it does mess with the roll centre and suspension geometry so you have to take that into consideration. The general consensus is with the gt86 you need to firm up the front more than the back when you lower the car because it has Macpherson stut front vs double wishbone rear....

Just a quick correction here. The stock springs have been tested as 2.3kg front and 3.7kg rear....

I read soem of the comments for a giggle. I can confirm fishmaster is a douche....

The stock springs for the GT86 are 3kg front and 4kg rear I beleive? its a 50% increase at the front! The 4.5kg yellows are designed to work with the stock dampers and mild track time. They do the Tarmac springs for after market dampers which are more aggressive 5kg. Their Coilovers go up to 10.5Kg

Quote: Originally Posted by Phaedrus29 Thanks for this explanation, although I can't say I fully understand it all! But I was a bit confused why other springs such as the Eibach Prokit ones seem to maintain roughly the same front-to-rear spring rate ratio as stock, but your Yellow springs have a very different ratio (1 to 1) from stock. It kinda SEEMS like with the Yellow springs you just said "Bah, let's just make the front and rear rates the same...it'll be simpler", but I'm sure that's not what it is, and it's good to see some of the reasoning behind the decision. So in your view, springs like the Eibach ones that drop around 1" and maintain a similar front-to-rear rate ratio as stock aren't getting things right? They aren't appreciating that the roll centers drop at different rates, the dynamic camber curves are different, etc.? Noooo not at all. We actually started with a softer front with our initial prototypes and while it felt pretty good, the car just got better and better with more front rate. We tried multiple configurations and did a lot of nerdy stuff too. I'm not going to say that springs that keep a similar ratio to stock are "doing it wrong" but the way we did things matches our tuning philosophy and hits our design goals. There is more than one way to do things and this is just the way we like best for a sport lowering spring on the standard shocks with good handling, good ride quality, and good looks. - Andrew

Comments from Andy at Racecomp Engineering: Quote: Originally Posted by gmookher sorry if its posted what are the rastes on the yellows? 250 lbs/in front and rear. 20mm drop front and rear. Much firmer than everyone else up front. This was done because the front and rear of the car react differently to changes in spring rates and drops. Instead of just increasing the spring rates by 10% front and rear, we did something different. The front needs an increase in roll resistance more than the rear does because the roll center of the front drops at a different rate than the rear when you lower the car AND the front has a different dynamic camber curve than the rear. A bigger increase up front meant better turn-in and things stay happy with the suspension loaded up in a corner with more grip. And it's easy to drive since you can put power down through the rears easily, especially with the stock rear diff. And with the mild drop plus our firmer front rates, you're not hitting our shortened bumpstops like the other companies soft fronts with bigger drops. - Andrew

I think the general consensus is that 5kg is possibly too high for UK roads. At the end of the day if you have stiff setup with appropriate grip, on a smooth surface it will grip very well, but on rough uk roads you may find it doesnt have enough complance and you lose grip compared to a softer spring. For daily driving the RCE yellow are set at 4.5kg/4.5kg and match the koni/bilstein dampers very well though the stock dampers can be used with the shorter bump stops supplied with the springs. I know someone with Ohlins (which are the road and track focused coilovers) on his car and was resonably happy, though I think he thought 6kg/6kg was too high.....

It isnt even close to a drop in. The FA20 was designed to be compact to fit in a GT86/BRZ. The closest thing would be an FA20DIT but even then it would require a fair bit for work. Stu over on the other form looked into it. The FA20DIT does give you an idea of what subaru considered nessessary to add force induction to the FA20....

Lauren - Over on the FT86 club Race Comp Engineering discussed the reasoning for a square setup. Their highly regarded RCE Yellow and Tarmac Springs are square (well almost - tarmacs are 5kg/5.1kg) and a lot of people were questioning why they didn't just add 20% front and back or whatever, like eibach and others, to keep the same ratio as the stock setup. The reasoning is how the roll center at the front and back of the car changes with a 20mm drop. Race Comp Engineering really know their stuff and give lots of good advice on the ft86 club.

I've been looking at the various options for suspention. Bare in mind the roll centre of the car reacts differently at the front than back when lowering the car. WIth a 20mm drop it seems you need to stiffen the front up more than the back to maintan the balance of the stock setup..... This is why most coilovers are the same front and back rates. The ohlins are 6kg/6kg front/back......... Coilovers with hard top mounts will never be as good over a rough surface as the rubber mounted OEM. I quite like the look of the Bilstein B6 shocks with Race Comp Engineering Yellows for daily driving and mild track use. They get good reviews in the US. Though the B6 shocks might need revalving to match the RCE spring rates which is not cheap.....

I have the storm force 4 layer bad boy. http://www.coveryourcar.co.uk/store/product.php?productid=18379&cat=752&page=1 Would you be interested to buy mine? I have the security kit too (padlock basically). As I say it was used for about 2-3 months. Dunstable is only about 1h drive from St Neots....