I received a message one day from Sami inquiring if I had successfully setup sequential twin turbo's on a 2JZ before with after market ECU, also sending me a link to a guide from a forum post on how to do it. I smiled, as I had written the guide in question many years ago, so told him he was speaking to the right person. After that, we made some plans on what he wanted to do with his Supra.
His supra was previously a full competition spec drift car, fully stripped, caged and all the modifications you need to get a Supra sideways. He told me he was in the process of completely converting back to a stock body, stock setup, full interior road car, but with the added twist of using Munro Stage 4 twin turbos and some extra OEM+ features.
This conversion was no small undertaking on his side, so we kept in contact until one day he messaged me that the car was as ready. We spoke about his requirements and came up with a parts list for the electronics, sensors and miscellaneous parts we might need.
Soon after I was on a flight to Oman with a bag full of parts and tools
If you didn't tell me, I wouldn't have guessed this Supra used to be a drift supra. It looked very stock, so the team had done a great job there. There were a few questions about some OEM wiring looms that we checked out and tested, then afterwards I prepped a Link ECU plug and play ECU, some wiring looms for sensors and worked towards getting the car started.
One evening we got the engine running, confirmed the engine was healthy and started doing some small drives around the block checking everything on the car felt like it should. After many iterations of this we felt good with the mechanical side of the car, engine responded well and the turbo's were working sequentially.
There were a number of seemingly random/intermittent wiring related problems on various parts of the car, so had to spend quite a lot of time diagnosing & testing what was causing them. A lot of the times it ended up being a connection issue between terminals on a connector. Maybe a combination of 30-year-old looms and being removed and installed a few times. Either way, we ended up having a great laugh over connection issues, and it became a running joke as the week went on.
So with the engine running and the car behaving mechanically, I turned my attention to installing an audio system, converting the dials and HVAC unit to brighter/modern LED's using JPWorx Kit. The idea of having cruise control & traction control was also talked about, so we converted the engine to use a factory ETSCi drive by wire unit.
I wired in the new DBW which freed up some outputs, so now we could have control of the OEM dash lights for traction control & cruise control indicators. Also added all 4 wheel speed signals from the ABS ECU and a two rotary switches, so Sami could control the engine mode and traction control mode on the fly. Also added in some beefier wiring for the 525 Walbro fuel pump.
Looking at it, it all looks very stock which was the idea behind this. Only the eagle eye people out there would notice the subtle changes indicating the big twin turbos and other features.
It had already been a few days by this point and we were all eager to see how it performed, so we started going for a few more drives, slowly tuning the engine with all the new setup and were happy that everything was as good as it could be, so booked a dyno rental appointment at a local performance shop.
But first we stopped by an alignment shop, showed the guys how to setup a Supra, and after dialling in the suspension they picked up on a stripped thread on an adjustment bolt. So headed home after and changed that out for a new bolt.
Next day we headed to the dyno and spent a few hours on the dyno sorting out the engine calibration and dialled in the sequential turbo operation to make it as seamless as possible even, testing what the Munro twins liked and what VSV timings I could get away with. Made 510whp at 1.5 bar on petrol and stopped there as more was getting close to detonation threshold. Being a stock engine with some 264's we decided not to push it hard just for a number, better to keep it reliable.
After the dyno we spent many hours on the road checking and confirming the tune, setting up launch control, no lift shift, cruise control, sequential/TTC switching and some other requirements from Sami.
During all of this, Sami raised a great question about trying to get the turbo's transition point to be as optimal as possible in every gear where the engine load would change drastically between say 1st and 5th gear, in order to get the best possible 0-60 and drag times. Although the turbo's worked sequentially, both turbos were larger Munro units, so were naturally laggier than an OEM setup if the second turbo didn't get prespooled in time for the transition, especially noticeable in the lower gears.
To make a long story short, due to the differences in load in each gear, the amount of exhaust flow at a target RPM would be different, so telling the ECU to transition the turbos at a fixed RPM point meant that in the higher gears it would work as intended, and in the lower gears you feel a dip as the second turbo wouldn't be able to be prespooled enough so the dip you would feel is the time it took for both turbos to hit targer boost after the transition. So I made some new tables and logic that took into account what gear we were in, how fast we were going and what the driver demand would be requesting in order to determine what RPM various sequential turbo VSV's would react in order to get as close to the optimal transition point in every situation.
Sami is a great example of a customer who knew what he was talking about and we were dialling and theorizing about some advanced stuff out on our tuning session, a real pleasure to have that constant feedback loop as we worked through everything. We finished the tuning session early in the morning, grinning and high fiving at a job well done and a great time. New friendship made and another cool Supra back on the road.
The next day I was back on the plane heading back to the UK feeling good, dreading the cold weather after being spoiled by 6 days of sun and warmth.