So had a bit of a break after the last few tests with the car and set my eyes on making some more adjustments to get my ET down.
First off, on the last santapod test day I noticed that #6 EGT was skyrocketing compared to the other cylinders on boost, when just 12 hours before on the dyno it was perfect. I tried all the usual suspects over a few runs by changing timing/fueling/dwell times etc, but no tune changes influenced the behavior. I didn't have a spare set of plugs with me or any diagnostic equipment so I figured at worse it was gonna be an exhaust valve that wasn't fully sealing and decided to keep sending it till it got worse. Luckily it just did the same thing everytime and didnt appear to get any worse.
Back at base the next day checked compression, leak down, valve shim clearances, spark plugs, made sure the EGT probe hadnt moved etc. Everything seemed to be within the working window and couldnt find anything obvious on the mechanical front.
The spark plugs I were using were about 4 years old and used on a variety of fuels and been sitting for ages in between the build time (yes im cheap). Also left them at 0.7mm stock gap, just to see what I could get away with on the IGN1A's. Dwell time was around 5ms, so getting up there but certainly not maxing out what the coil could handle. Anyway, swapped in a fresh set of BKR9EIX's, gapped down to 0.45mm and immediately everything went back to normal. Could also drop my dwell to 3.8-4ms without any misfires on the dyno, so I'm gonna put this down to old plugs/large gap causing a meh burn in #6. Thankful I had my EGT sensors to show me what was going on. Interestingly the lambda reading on cylinder 6 was perfectly inline with the other cylinders, so I would of never guessed this was going on as there wasnt any audible misfire on boost etc.
So with the engine in good health for more abuse onto the next parts.
Reviewing the footage from the previous launches we could see there was quite a bit of wobbling/movement from the rear wheel hub as it was trying to grip on the launch. Furthermore, the suspension would initially squat and then rebound shifting all the weight to front again. This was of course no surprise with some entry level yellow speed coilovers and a mix and match of 30 year old arms with polybushes. So ordered the following to address some of these issues.
IDS Front/Rear Triple Adjustable Supra Suspension Setup
IP Upper Arms + Drag Anti Roll Bar Setup
Japspeed Lower/Traction/Toe
The aim with this was to finish off the "solid" rear setup by having rose joined arms all around to complement the solid subframe & solid diff mounts. Getting rid of any wiggle from any old bushes/joints should help keep the geometry more consistent through launching and transitioning into the rest of the track. Also allows for much more potential geometry setups as no longer confined to OEM adjustment restrictions.
The IDS suspension was there to help control the weight transfer from the front of the car to the rear and keep it there in both the short/top of the track with its valving setup for a Supra and adjustable rebound/compression and high/low rate delta changes in the suspension.
Also got a new torque converter delivered from Pure with the aim of it being a bit looser than the last one so I could get a bit further into revs/boost whilst footbraking on the launch.
Love the eyelet mounting setup on these, makes taking them in and out a breeze compared to stock.
And Done
Panda ready for the next Santapod session
Straight off the trailer did a 9.0 with a meh launch. Did a few more runs dialing in the new torque converter and suspension and did a 8.88 run at 2 bar boost. Not bad.
New torque converter from Pure was certainly a step in the right direction, can get to around 4000rpm on the line and thanks to VVTi, once i hit 3800rpm the engine wakes up and I can make anywhere from 1 to 2 bar boost off the line, so plenty of boost to choose from now. Going down the strip I can tell the converter slips a bit more than before, averaging 3% slip at higher RPM and slips way more coming off the launch which is better I think. Just need to put my big boy pants on at some point and throw all the power this combo has at it and should be pretty quick.
The new suspension was working great, finally getting some decent suspension movement and no more wheel wobble. Would of almost been perfect weight transfer if I didnt ride the limiter in second, which I thought was me being slow on the shift but actually turned out to be an old setting I had from the last drag race.
Found out after that run I was having a really lazy third gear change due to some old settings I had in from the old torque converter where I was lying to the TCU about the amount of torque the engine was making to soften the shift as I had crazy wheel spin previously, easily lost a few tenths in between riding the limiter and waiting for the third gear shift to engage properly. Duly reminded the ECU/TCU that in third gear we were in fact making north of 1100nm not 400nm.
With a few practice runs and most tuning tweaks identified and addressed, I was ready to go for it. Turned up the boost on the launch from 1.3 bar to 1.8 bar and was gonna target 2.5 bar down the whole track and try to get into the low 8's.
And then this happened
30 year old NA axles I salute you, you lasted many years but today was the day haha.
Cant say I'm upset, certainly taking the piss with OEM components now. (hopefully OEM prop/driveshaft can take a few more beatings 
)
Overall the car worked really well all day other than the axles, so not really going to change much other than the following for next time.
- Hook up the dry nitrous shot, see if I can get my stallspeed from 4000 to 4500-5000 before overpowering the rear brakes.
- Adjust my brake pressure to brake light signal ratio slightly. Theres a small delay between the point at which the TCU removes any clutch/converter slip it uses during the launch to maintain no output shaft rpm to keep the car from moving. But my brake light signal dosent become inactive until im fully off the brake pedal, but because im loading the driveline so much it wants to push through before that point. If I can get the clutch/conv slip to engage at the point the car actually wants to move forward even if im not fully off the brake pedal then might be able to gain a few tenths as I should be moving forward with more drive rather than having a small delay.
- Uprated axles and a spare prop/driveshaft
Should really go to a ford 9'' or similar, but I'm very interested to see if the new billet gears in the small case can take the abuse or not, so I will keep going with that until I find its breaking point.
Until the next one.
Cool video Ash made about the day