Ade

There is very limited space under the seat. I have a couple genesis profile amplifers under my seats. They are 40mm high and I mounted them on 9mm MDF glued to the floor. They just clear catching the seat near the rails. I opted to make a moulded sub box in the boot that sits flush with the liner Sub Box1 by Adrian Carter, on Flickr Resin Base by Adrian Carter, on Flickr Finished box by Adrian Carter, on Flickr Sub in place by Adrian Carter, on Flickr Finished by Adrian Carter, on Flickr

To suggest the flex As are even close to the Ohlins is ludicous. Nigel spent best part of 100k making a track car that eventually got scrapped before it was finished. His other gt86 that got the Ohlins was used to drive a few miles to his work and back, never used on track at all. The guy loved to tinker but wasn't a driver. How do I know this? I bought my Ohlins kit from him. I went to his house and met the guy and saw his work. Smart guy with good fabrication skills but to say flex A are better than Ohlins based on a 3 mile drive to work is silly and utter rubbish.

Ohlins with 60N/mm all round are not bad at all. I forget the numbers but of the top on my head, with 2mm passenger side and about 7mm preload driver side, with me in it - its got about 15mm free travel then another 40mm of bumper stop travel (progressive bump stops). Honestly if you need to bump travel due to the road you drive on then not many coilovers will be much use. The only ones I would look at are the bilsteins are they have lots of bump, but they wont be as good on track - but who care unless your racing?

I did a 0-60 in 5.3s without a proper launch! Trying to get below 5s is a skill as 1st gear just lights up the rear tyres, but I do believe with a good launch its possible and helped by the fact that my wheel diameter means the Speedo is spot on and the car can infact do 60mph in 2nd.

its a dual clutch gearbox iirc. From a standing start you would be screwed as it has 4WD but from a rolling 50mph youd at least be able to stay will one, if not edge away.

Torque and rpm are what makes hp. If both are 300hp then wheel torque after gearing has been taken into account will be similar. The golfs are notoriously under rated though so more likely 320hp. A revo golf R is very quick indeed.

Unless you were doing more than 110mph 5th wouldnt be the gear id select! Golf Rs standard I wouldnt expect to be any quicker, but with Revo ~380hp they are very rapid.

My Custom Hayward and Scott Cat-Back Design and Proving Introduction **If you don't want to read at the theory, skip to the end where there are pretty pictures and a video** Firstly I should point out that I am a bit of an old man and dont like noisy exhausts! LOL. Please dont take any of the following as a criticism to any aftermarket exhaust; I just wanted something that is quiet under full throttle until higher up in the revs. This then gives me some headroom to further modify the exhaust. My current exhaust, the Cosworth Cat Back, measures 92dB supercharged or 89dB N/A, so not particularly loud but when cruising on the motorway, 6th Gear, 3k rpms and going wide open throttle, I found it to be very boomy in the cabin when it was hot, particularly after a track day. Even with cruise control on when coming to a hill, the slight throttle was enough to annoy me on longer drives which are becoming more and more often in my GT86 these days. How on earth some of you live with 100dB exhausts is beyond me! Its not a criticism of the Cosworth cat back; I still think it sounds awesome and I haven't come across any other cat back for this car that is quiet when under WOT at low revs either, apart from stock. Certainly it's not any worse on the Cosworth 0.1 than other exhausts I have sampled in the 92dB range. Silencer Theory Straight though absorption silencers used in most aftermarket exhausts dont attenuate sound very well at low frequencies. It depends on the length, volume and packing material but generally they dont block as well at lower revs as they do the higher. The reason for using these silencers is that they dont restrict flow like a cambered silencer (stock). I decided to do a bit more research into OEM silencers and how they work. It turns out that a stock silencer typically has two or more chambers inside but each chamber often has a different target frequency range. I am not going to get into detail but here is a diagram of a typical 3 chamber silencer. Each chamber is a different design targeting different frequency ranges. And here is the insertion loss of the different straight silencer types: The tuned pipe, otherwise known as a branch resonator or sometimes mistakenly called a Helmholtz resonator is quite a popular DIY for helping drone. Its length is designed to reflect sound waves 180 degrees out of phase at the target frequency. The result is noise cancellation but the Q is quite high so it doesnt have a very wide range. At the target frequency of 100Hz and 150C gas temperature, the pipe would need to be about a meter long! Here is one such example (borrowed from the ft86club): I had noticed that some Cat Backs do have Helmholtz resonators, namely the ARK Grip and HKS HI Power Spec L. I havent heard either to comment other than to say, looking at my calculations and the images, it looks to me like they dont target 100Hz as the cambers are a bit small and both seem a bit loud for my goal. The Helmholtz does look appealing though, as it has a lower Q, so wider attenuation range and the packaging is much nicer requiring a big air chamber and a neck, bit like a bottle. Hayward and Scott I decided to speak to Ian at Hayward and Scott about a custom Exhaust as I have always been impressed with their work. Originally I asked Ian to make me a large single absorption silencer like the Q300 or Miltek but to connect up to the 3inch Cosworth mid pipe. The intension here was to add additional resonators in the front or mid pipe if it was still too boomy at low revs. After some discussion with Ian I decided that it was better to start with a whole new cat back rather than chop up the current one as Ian was sure he could get a much larger center silencer in the tunnel. We decided 70mm (2.75inch) pipe would be a good compromise and we should keep the Y design as it has the best flow. He also explained that they have a small chamber built into their silencers too which may help, so I left the car with them for a week while they made the system. Here are some pictures of the finished product: Ian has a catalog of exhaust tips but I liked a twin wall rolled and these with the perforated inner did the trick. Actually, originally I said I wanted a design similar to the Cosworth/Nameless/Perrin but Ian fitted the rolled and I decided to keep them when I saw how nice they look. Ian knows best! J The results were very good. Much quieter and a pleasing rumble, however on the drive home I wasnt quite happy with the 3k rpms WOT boom. Although far quieter than before, I wanted even less, but the top end was perfect. Helmholtz Design I decided to look in detail at a Helmholtz resonator design. First port of call was Wiki! https://en.wikipedia.org/wiki/Helmholtz_resonance Next I made a spreadsheet to calculate the required volume and neck lengths from the formula on the wiki page. At this point I want to thank the few engineers; Frederik, Dan and Matt who checked my sums weren't completely wrong! Also another good reference was a paper discussing using the muffling effect of Helmholtz Attachments to a gas flow path http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2200&context=icec I decided to copy the ARK style arrangement, with two Helmholtz resonators mounted in parallel to the rear silencers as this was the area under the car with the most space. Also two would work better than one. They would be quite a bit bigger than the ARK design though, targeting 100Hz. Once I was happy with the design on paper I made a mock up from cardboard and plastic pipe to check it could fit where I had space. The only real issue going forward that was highlighted could have been if I got the gas temperature wrong, as I had used a thermocouple in the exhaust pipe which wasn’t right at the point the resonators would attach. I measured 150C which I though was realistic near the back boxes. So back on the phone to Ian at H&S to get the Helmholtz chambers made up and welded on the existing pipework. Ian managed to tuck them up a bit so from behind you still see the nice H&S boxes Here are some pictures. I think it looks awesome! The result is a reduced 2-4krpms noise and just a nice background rumble when WOT @3Krpms. And to show the effect of the Helmholtz here is a graph of before and after: There is about a 10dB reduction downwards of about 100Hz (3k rpms) which equates to sounding about half the volume. In terms of how it feels, the noise power is 10 times less! Finally a little sound clip Final Specs are: · When hot 83-85dB @5k rpms (45degree, 1Meter), though at Bedford they told me it was 79dB. If you N/A reduce this by about 3dB. · 70mm internal pipe diameter splitting to 2x50mm pipes · Low level hum when WOT at 2k-3.5k opening up to a nice refined tone above 4k · Y design for a smooth gas flow · Stainless steel with a lifetime warranty (check website for terms and conditions or talk to Ian) · UK made · Personal touch being able to select from a range of exhaust tips Well thats just about it. This was much longer than I intended but I am very happy with the results and wanted to share my findings. Thanks to Ian for his craftsmanship and help designing this amazing cat back, and also for his quick responses to my emails over the last 3 months! I cannot recommend highly enough. H&S also do a selection of 2.5inch options with different middle silencers (or none at all) that are worth a look. https://www.haywardandscott.com/toyota-gt86.html If anyone has any questions, do feel free to ask away. **edit - added pricing** So pricing looks like this: Cat-Back with 70mm piping and the extra larger center silencer £650 + VAT Exhaust Tips of your choice: Varies but roughtly ~£75+VAT Helmholtz Resonators: £275+VAT Above priced are fitted. ease note this system differs from their standard offerings in that it has 70mm pipe diameter and the extra larger middle box is bigger than their "larger center silencer" on their website. If in doubt talk to Ian at H&S about your needs.

Hi Adi, pop me a PM and can discuss. Just recently I helped a guy with his cobra. We had to modify the dimensions a bit but the target frequency was the same and worked a treat just with one resonator chamber.

Intake temp will vary quite a lot depending on airflow through the intercooler and how much work the charger is doing. At the track you should see about +25-30C over ambient depending on the circuit and driving style, with the Harrop kit.

Congrats! 260 hub is about the same as the cosworth stage 2.3 Mark had on that dyno. Numbers on their own mean nothing though, it relative to stock stock ~170 then going SC + exhaust gets you ~260 which is a +53% gain. I concur it just feels like a bigger engine. power everywhere P.s. I am sure mark will happy to adjust the throttle mapping if you cant get used to it. I have two different throttle mappings for different situations.

I had a 1.6 Supercharged C180K Merc. The new models replaced the SC with a turbo and gained a few MPG combined, for the same power output. Turbos are a bit better for fuel economy than supercharged, its only about 5% based on the Mercs but in todays market where a few hp matters, turbo wins. You still get better fuel economy from a 200hp 1.6 supercharged than you do from a 200hp 2.0litre high revving N/A engine. Partly because the higher revving engine has shorter gearing to make use of the higher revs (to achieve the power). My 86 is doing about 3k at 70mph. My 20d BMW is doing half that with it 8speed gearbox. Frictional losses for one are lower with less revs and as been said forced induction improves thermal efficiency of the engine. Next gen 86 if it does go ahead will have to be turbo or supercharged to keep costs down I would think.

Big turbos lack low end torque and throttle response is not as sharp. Centrifugal SCs are belt driven turbos and also lack bottom end but sharp throttle as they are always spinning. Smaller turbos are better too. On plus side (big laggy) turbos can do big power, give better fuel economy on motorway and often have less complexity. E.g. air to air intercooler vs air to water to air that the roots chargers have and having to take manifold off ect... I'd go for a small turbo if you don't ever want more that the 280hp Rob lottery territory. Placement of some of the turbos in the kits concern me too.

This is sort of true. At wot 5k standard track day test it should be about 3dB louder with +50% more airflow. When cruising you are correct it shouldn't be as pronounced but it is still a tad louder due to a bit more load on the engine.

Some of the guys in the states use W40 oil and the TMG race card use 15W60. However they warm the engine up before driving. Toyota recommend 5W30 for hot climates. I would recommend 5W30 if you want to do tracksdys and don't have a strong oil cooler.

Indeed. I painted them when I got the car and started doing trackdays in it about 3 years later. Black also wouldn't work as it chars and flakes off 🤣

It needs properly diagnosing before taking the engine out. I agree that I wouldn't rule out direct injector seals as one possible example that can cause a knocking sound. Its not always a big end failure. £17k for a engine has got to be trolling. Bet they had a great laugh about that in the office.

Nope and you'll love it. It just feels like a 3 litre FA20.

The length of the intake ports should be tuned to give you peak power where you want it. Higher rpm generally means longer runners for peak power. I dont know the exact numbers, but its part of the reason its such a big kit, the other being the large intercoolers. Some OEMs like Mercedes have variable length intake manifolds so you dont have to compromise. Its a bit like variable valve timing. Years ago they were fixed and tuned to give peak power (torque at high rpm), then Honda came along with VVTI and their revy 8k rpm engines actually had usable torque lower down.

Well firstly perhaps you were not aware, Matt tweaks the maps to suit your engine. I think I had 3 or 4 iterations after installing my kits before it was spot on. Currently on the 8th iteration as ive added bits and ask for changes. This is over 3 years. Cosworth tested a variety of exhaust manifolds during testing/development. You've probably seen the H&S one doing the rounds, but they also tested a few other manifolds. So from that data Matt can customize the tune and tweak it. All you need to do is get some nice datalogs and send them and he will adjust accordingly.

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I agree with some/most of the bits Will is saying but I will add a few (try to be non biased) to that. Design c. I am not aware of anyone needing to cut a section, but yes you may need to put a small dent using a ball peen hammer. Design e. Due to it compactness the intake runner lengths are not tuned properly. They are too short. This is one of the reasons why the Cosworth running 0.5bar makes the same power as the harrop running 0.7bar boost. The other reason is the bigger more draggy TVS and the tuning to balance cylinder pressure which can only be done with incylinder pressure sensors (standard tunnig with OEMs and serious motorsport). Performance e. Its a fair point the most powerful Cosworth is their dev car running ~330hp. However, I am not aware of high power 400hp harrops that use pump gas? All E85 which help massively with high IATs. General advice I see is 12psi max on pump and you need E85 if you go for more boost due to heat and pulling timing. Cooling: Yes at 280hp both are fine, but running high power is where is were the nearly twice as good cooling (Coswroth is +15iat, harrop +25iat, Edlebrock +30iat) would come into it. Where the Cosworth could be +35iat @400hp, the Harrop will be +60C and the Edblebrock +70C. Tuning: Here is my main disagreement. The Cosworth was tuned on an engine dyno and it specific to that kit. You cant take things Matt has done differently with their SC kit and apply them to the other kits. Its not just the engine dyno tuning either, they use widebands in every exhaust runner, and cylinder pressure sensors to properly dial in each cylinder and evaluate things like how well the stock knock sensor work ect.. Its a different kettle of fish. Tuner dont typically use widebands and thermocouples in each cylinder runner, they just poke a wideband sensor up the exhaust. They certainly cant measure cylinder pressure and balance them out or evaluate if the knock sensor is doing a good job or not. For me the defining decision to go Cosworth was the tuning. Yes most people are happy with dyno or road tuning but for me I wanted the real deal OEM engineered solution. If I were choosing now, I would be on the fence a bit for some of the reasons Will has given and the fact that Cosworth are getting out of the game. Matt@cosworth still gives excellent support and he isnt likely to leave Cosworth any time soon as he is very well respected there, but you never know....

100% agree. Lotus Exige 350 V6 would be my other motor to compliment the gt86.

Foliatec it was about the highest temp paint I could find! 300C. That was after a few trackdays. The issue of the floating bit of the caliper. It has a larger surface area that conducts heat from the pad very effectivley, so it gets very hot. You can see at the back where the piston is touching the pad, the paint survived. Also RIP to the red rubber grease used on the slider pins.