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BOBEL

GT86 Racecar build

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To be honest the KWs were on the car when I got it and that’s the way JRM installed them, so I’ve left them like that, I don’t think it should make any difference really so I don’t think your missing a trick :-)

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As the lockdown tennis continues I took full advantage of Black Friday deals before Christmas and decided it was time to address a few items that were always on the list

First up was getting a new set of wheels, I’ve been running a set of 18 x 7.5 OZ Ultraleggera for the last number of years and it’s limited me to 225 section tyres, and now with the extra grunt traction can be an issue on all but the newest tyres, I’ve got around this by running slicks in the summer but its limiting when you get a spot of rain (as we often do in Ireland)

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So I opted for a set of Konig Hypergrams 18 x 8.5 et38, and later fitted some Nankang AR-1 255/35 so they should offer a nice bump in traction (the photo below is just the old set of R888R 225s I threw on for test fitting)

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While I was fitting the new wheels I got distracted and decided to fit a tyre rack to my trailer so I could at least fit some wets to the old wheels and bring them with me

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Upto this point I’ve kept the external of the car pretty standard looking, but I always intended to fit some functional aero and I’ve always been tempted  by the Verus Engineering parts, so I took full advantage of their Black Friday deals and bought this lot!

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First up was fitting the adjustable front splitter, I opted to install it at 5” extension just too see how it will work, However the install of the front splitter was not straight forward as anything beyond a 3” extension meant that two of the tie rods would extend beyond the bumper,

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I ended up drilling two new mounting holes further back and making two offset brackets, I also ran into issues with the length of the tie rods, which at 5” were running at max extension with very little thread engagement left within the turnbuckle, so I installed some spacers behind the crash beam brackets to allow me to shorten them a little.

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I also went with the accompanying end plate and canards, while installing the end plate I decided to reinforce the bumper edges with some aluminum backing plates just to give the rivet nuts a better chance of staying put!

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Finally all were installed

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With that lot sorted I’ve still got the rear wing, and bonnet vents to fit.

I’ve also bought the Verus steering angle limiting kit, as the wisefab kit has given me some extra lock but on full the tyres are touching the inner wheel arch

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As my persistent 2nd gear grinding continues I also bought a new set of Verus carbon synchros that I’ll get fitted at some stage, and finally my battery was shot after 4 yrs of trickle charging and trackdays so I replaced it with a new Odyssey PC950

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Managed to get the last two major Verus Pieces wrapped up over the last few days

I tackled the bonnet vents first while I waiting on a few parts to arrive for the rear wing install. It’s always a little tense cutting into body panels so I must have checked my dimensions about 5 times before the drill and cutting disc were unleashed.   

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Once I had the holes cut out I taped up on both sides and sprayed all the cut edges just to seal them up and stop any aluminum corrosion taking hold.

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After all the messing about the vents were finally bolted in, safe to say the front of the car no longer looks stock!

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With the vents completed I tackled the rear wing install, I knew I was going to have to make some small alterations as I have a full fibreglass ducktail that covers the entire bootlid, and the Verus kit is designed to fit onto  a standard bootlid. However funnily enough the Verus wing is designed to work with a ducktail and the profile of the wing should nicely tie in with it.

In order to get it to work I need to drill through the various layers of fibreglass and bootlid steel and use some extended aluminium spacers inside the boot with longer stainless steel bolts. The wing then uses a stainless steel backing plate on the inside and aluminium uprights on the outside to ensure there is no flex, which is helped by the fact the uprights are right out on the edge of the bootlid. A jacking nut is also incorporated that you adjust so that it is in contact with the OEM boot hinge stopper to further ensure no flexing.

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When all was installed it does seem very effective, and ties in nicely with the ducktail like I hoped

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The last few weeks have been relatively quiet so I took the opportunity to fit the last Verus piece which was the steering rack limiters, pretty simple job which involves slipping some C-shaped spacers around the rack by sliding the rubber boots on either side back, should hopefully stop my wider front wheel from contacting the chassis on full lock.

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With that little job only taking a few minutes I turned my attention to something a little more experimental. With time on my hands I took a good look at my oil pressures from recent trackdays, and I wasn’t exactly loving the look of them. 

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My oil pressure sensor is installed on the mains and most people estimate the difference between the front cover where most locate their sensors and the mains is +10psi, but not being one to work on assumptions I’ve decided to install a second oil pressure sensor in place of the OEM oil pressure switch which I’ve ditched as its pretty much useless anyway.

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I know the FA20 is never going to have the most impressive oil pressure given the OEM spec is 46.6PSI @ 6,700rpm @120 DegC which is only 6.9PSI / 1000rpm whereas an old general rule of thumb is 10psi/1000rpm, but I would like to see some more pressure at the main journals regardless.

I’ve already got a Reimax high flow oil pump installed but ultimately I think the real problem with the FA20 is the fact the oil supply is not direct to the main journals, after it leaves the oil filter it splits to feed the left cylinder head before splitting again to feed the mains and right cylinder head so essentially the main bearings, and subsequently rod bearing are down the pecking order.

So I set about finding a way to essentially create a priority oil feed to the mains, I’ve seen others attempt this in various ways but I was anxious to combine the best of what I’ve seen with something of my own making and see how it works.

What I’ve gone with is an adaptor that I’ve modified to fit the FA20. The adaptor re-orientates the oil filter 90 deg and provides a direct tap into the post filtered oil. The adaptor will allow me to run a bigger diameter and longer oil filters without fear of hitting the underside of the bonnet which should reduce any pressure drop

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From the tap on the side of the modified adaptor I’ve run an oil line directly over and into the main journals where my existing accusump was plumped in. I’ve had to do a little reworking of the setup but it all fits nicely.

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With this setup the first route available to the oil is now the main journals, before it heads back into the front cover and into the heads etc.

One fear with this setup is that too much oil goes to the bearings and you essentially starve the heads, hence the real reason for the second oil pressure sensor. The sensor is wired to my AIM dash so I can monitor both pressures and set up a math channel to monitor the differential between both.

So I guess the next trackday will be the test-bed whenever that turns out to be!

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Are you going to take before and after measurements from both oil pressure sensor locations? with and without the new main oil feed to see what actual difference it makes?

I run an HSK oil cooler, 5w30 oil, and my oil pressure sensor is in place of the OEM pressure switch. Im cosworth charged to. On the road cruising at 70mph in 6th, with an oil temp of 75C I see 85PSI pressure. On a track day with oil at around 100C I see around 65 PSI at 7k RPM. IIRC

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Yes I probably will revert to original setup just to measure the exact difference, I imagine it is most likely +10psi at the front cover, and that would line up pretty close to your own figures @ 100 Deg C

 

I’m running the HKS cooler with 5W-40 oil so I imagine we would be quiet similar minus the oil pump difference, although I’m not sure that’s netting me much by the look of it.

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13 hours ago, BOBEL said:

Yes I probably will revert to original setup just to measure the exact difference, I imagine it is most likely +10psi at the front cover, and that would line up pretty close to your own figures @ 100 Deg C

 

I’m running the HKS cooler with 5W-40 oil so I imagine we would be quiet similar minus the oil pump difference, although I’m not sure that’s netting me much by the look of it.

So does that mean my numbers are +10 on on yours as your measuring at the main a the top of the block? Would be really interested to see the difference before and after the mod.

I would be also interest to know if your monitor IAT, if there it a noticeable difference before and after bonnet vents.

 

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Yep pretty much, I would imagine you are reading +10psi on mine as all my reading are from the mains, but I’ll know for definite once I gather more data from both locations.

Yes I have a IAT sensor just before the throttle body, I must check my data logs and see what it’s currently reading, but I should be able to show pre and post vent install alright.

I’m really hoping the vents will actually have an impact on the coolant temperatures as I think the post radiator air flow is very constricted with OEM setup, the front splitter should increase flow through the rad too but I guess the data will tell all.

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I have no issue with coolant or oil temps, but I want to get more air out the engine back, but I have yet to see data proof of the benefits. I think the bonnet vents will definitely give the air somewhere to go out the back of the rad.

I assume your on standalone management and not stock?

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Its been a little while  since my last update but finally lockdown restriction lifted here in Ireland and I got to a track day this weekend to test my most recent changes and most importantly the oiling modification. 

After downloading the data it looks like the modification has yielded the result  I was looking for and has raised the oil pressure at the mains. It was hard to do an exact head to head comparison, trying to finding two laps with the exact same oil temperature but these two are relative close (the post Modification one actually being a few Degrees hotter)

Oil pressure & Temp Post Modification

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Oil Pressure and Temp Pre-Modification

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When overlaid you can see that pressure at the mains has consistently increased.

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I'm happy pretty with the results at the mains, but I also logged the oil pressure in the front cover and turns out the pressure delta was minimal so the heads are certainly getting enough oil too.

Oil modifications aside, I also ran the car on 255 section Nankang Ar-1s this weekend on the new 8.5j Konigs, compared to my usual 225 R888s on 7.5J Ultraleggeras and the grip was immense, however I think I'm at the point of needing to change the ARBs though as I'm getting a bit too much lean through a couple of corners.

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Pretty cool stuff throughout. Missed this thread until now. Have to ask though, with all this effort why did you choose the only SC known for repeated failures?


Yes agree they have a questionable reliability but my preference was a centrifugal charger with air-air intercooler so choices are quite limited, I also love the power delivery and think it really suits the car, but perhaps my mind will change when it come time to replace it

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