This just made my OCD tweak!

 

Yeah, there's a wheel stud needs replacing there!!

 

I should hope not, they aren't that old lol! Thanks mainly to Kwik Fit and their inability to read a torque wrench correctly

 

RPC chromoly flywheel has arrived. Looks a nice bit of kit for a good price, comes with the spigot bearing too. It’s advertised as weighing 6.8kg but on my scales it comes out at 5.7kg. Should make a nice difference to response when fitted.

 

Clutch and flywheel went on over the weekend, and it’s the first time I’ve used this combination (Exedy Pink Box Clutch and RPC Lightweight Flywheel) on a 2.5, so thought I’d write up my findings in case anyone else is thinking of going down this route.

The clutch is fairly stock feeling, it’s not difficult to depress but has a springier action and snaps back quicker due to the uprated clutch springs. This is no bad things as it makes gear changes quicker. The clutch is much grippier than stock so there’s minimal slip before pulling away. It’s not an on/off switch like you get with a paddle clutch, but it’s more direct than the standard clutch. Other than that, you wouldn’t know anything had changed, it’s quiet and easy to use.

The flywheel I used is 5.7kg which is much lighter than the standard 10kg’ish standard unit. This takes a bit of getting used to as it requires a few more revs with low speed manoeuvres. This is due to the reduction in rotational mass. You can pull away with hardly any revs with the standard flywheel, you would just stall doing that with this. The upside is that acceleration is improved and the engine spins up much faster. Rev matching is fantastic with this clutch as a quick blip has the revs up to where you need them almost instantly. Engine braking is still the same and everything else feels pretty much stock. I’ve never used a lightweight flywheel on a 2.5 before so very pleased with the differences. Acceleration is the biggest key here, it really does pick up quicker than before, but that’s no surprise with a nearly 50% saving on rotational mass at the power plant. 👍🏻

 

Wow that is very detailed, never thought about it on take off.

When you say you have to give it more revs does it feel like you need to do it to catch the bite if that makes sense.

 

Hiya bud, due to less rotational mass it just takes a couple of hundred extra revs when you pull away to keep the engine from stalling. The biting point is still the same as it always was. The standard flywheel is heavy to keep the engine spinning over between the cylinders firing, having half the mass means that it's not as keen to do that now. It's not a big deal and something you adjust to very quickly, and probably sounds more of a big deal than it is. After driving the car a few times you won't even realise you are doing it. For me it's a very small negative that are far outweighed by lots of positives. It would in no way take your enjoyment away from a car that is a daily driver.

Hope that helps?

 

Thanks for explaining that mate.

I want to go billet when I change the clutch. I'm getting too old to daily a scooby now but when I do go out in it I want it to be driveable. Thats why I wanted more information on it

 

Mine is billet, you can get various weights. Something like a 7kg would make it a little less likely to bog down but will still see most of the benefits. It would be a good trade off between the two.

 

Had some free time today so thought I’d do a compression test just to see how the standard block is holding up, and I’m pretty pleased with the results:

Cly 1 - 145
Cly 2 - 143
Cly 3 - 145
Cly 4 - 144

Don’t get me wrong, I know how much of a lottery these cars can be and that I may just have a good one, but I firmly believe that with good servicing, the right preventative mods (elh’s, AOS etc) and a good map, they can take some power. I’m not blind to the fact that it could still fail as I am pushing the standard bottom end, but I’m happy with those results for now.

 

Another update on the car, in the interests of keeping the stock engine going for as long as I can I’ve invested in Cosworth Stopper Head Gaskets and 11mm ARP Head Studs, heads obviously went off to be skimmed and refreshed. I’ve also taken the opportunity to remove secondary air pump.

Now I know a few of you would probably think it’s false economy not just having the engine built while it was out, but my mantra is don’t fix what isn’t broken, and the strong compression results the engine displayed in my previous post gives me confidence that the standard block is still going strong for the time being. If it does fail, I will rebuild it then.

 

Car looks pretty damn good!

How are the brakes? How do they compare to stock? Any track time on them?

 

Thanks Graham. I’ve not had a chance to track them yet due to Covid but they are definitely a clear step up from the standard Brembos. I was put on to them by a friend who uses them on his Time Attack car and has won his class for the last few years, setting numerous class records. I wasn’t very impressed when I drove a car with the older two piece caliper design, but these new single piece forged calipers are miles better with no flex now. Im hoping to get out soon to give them a proper test.

 

I keep forgetting how long COVID has been going for! Only managed to spectate one track day last year and had to blag my way in!!

Good to hear, because I had a set on my supra many years ago, original design by the sounds of it and they were better than the original jspec brakes. But Im now coming from a GTR with a fairly decent Brembo setup (alcon discs, pagid pads) so would like a decent brake kit when I finally get a car and back to the track. Would be very interested when you do finally get finally get to test them in anger!

 

Its certainly been a hell of a year! I will certainly update you once I get to use them in anger, very happy with how they are performing so far as fast road brakes, but obviously haven’t got anywhere near their limit just yet.

 

Took the car to Santa Pod today, the new clutch and lightweight flywheel took a bit of getting used to when launching but managed a 12.5 quarter mile at 107mph. I ran a 12.6 too, but at 108mph but had a poorer launch. I changed up into fifth on the 12.5 run which affected my trap speed, so there should be a 12.3 in the car.

 

your brave doing that with the standard block

 

If it goes, I’ll build it, but it’s been running 1.6bar for over 10k miles now with no issues. Hopefully the combination of equal length headers, a quality front mount, AOS and lots of hours of careful mapping will keep it going for another 10k 😊

 

Think we met at a5076 after Tesco heading to Swan Valley

 

Ah yes 👍🏻. That’s a beaut of a car mate!

 

Cheers, swap
Joking i love 8k redline on mine
Nice touches/ upgrades on Yours👌

 

I do fancy another newage at some point, great cars. I’ve grown very fond of the 2.5 in mine, I missed the revs at first, and yes they can be temperamental, but the torque on them is immense. Thanks bud, I’m sure we will pass each other again.

 

Think You will be able to rise revs when You forge it. Was Yours on XXR wheels in the past or there is/was another blue Sti in Northampton?

 

Yea I may well get some head work done to allow more revs in the future. Yes that’s correct, it was on XXR wheels for a short while.

 

I bought enkei alloys of You than👍 ,sadly did not fit over my 362mm apracing brakes. I sold enkeis and bought rota grid neochrome for summer keeping old hyper black rotas for winter tyres.

 

Ah that’s right! That’s a shame they didn’t fit over your brakes. I loved your car, one of the best I’ve seen 👌🏻

 

Some impressive consistency there and like you said the car has more. Are you using launch control or manually doing it.

 

Thanks bud, bogged down on the first couple of runs as the lightweight flywheel takes some getting used to. It doesn’t have the mass of the original so you have to be a little more aggressive with the revs and a little quicker with the clutch, but once I’d figured it out it was fine and it hit a 1.7 60ft pretty easily.

I don’t have launch control unfortunately, but would definitely help if I did so will be going down that road, so much easier to be consistent with it.

 

You can then focus on reaction time

What about flat foot shifting too if you are going to get it mapped in.

 

True . Again, something I will probably get mapped in and will have its benefits. I’ll end up going stand-alone ECU eventually so can also have anti lag, rolling anti lag and all those other goodies too.