New Engine - Same Tune?

I installed Microsquirt on an unknown mileage B230FT with T3/T4 50 trim turbo. I had a local shop dyno tune it. Peak 187 TQ / 200 RWHP @ ~12 PSI. Since then I used auto-tune and megalog viewer to dial in the fueling. Overall we were happy with the performance for Lemons racing. At our last 24 hour race, we went through 5 gallons of oil, so we pulled the engine to keep as a backup.

Meanwhile, I rebuilt a B230FT squirter block. Sleeved cylinders 1 & 4 and bored all to +1 piston size. Added new +1 stock pistons, china rods, oil pump and bearings. Transferred recently rebuilt head from old engine and put on new engine. I have no idea if compression changed. I did pull the VX cam and replaced with an IPD turbo cam. No other changes.

After connecting everything, engine fired right up. I let idle for a bit, then turned it off.

My question is will the Ignition and AFR tables transfer over to the new engine, or do I need to have someone smarter than me rebuild those? I am assuming I will just autotune the fuel tables at the track. I cannot street tune, my options are dyno or racetrack only.

How aggressive is your spark table? If it's not too bad, then I'd just dial in the fuel tables at the track and listen for knock during your practice sessions.

I can say that when going from a stock b230ft head to one that was ported and shaved to raise CR to 9.4:1, I had to pull 4deg of timing at peak torque (2deg eliminated knock, the other 2 were for safety). This was at 20psi though.

Same cam and compression ratio?

Is it running in closed loop?

culberro said:

How aggressive is your spark table? If it's not too bad, then I'd just dial in the fuel tables at the track and listen for knock during your practice sessions.

I can say that when going from a stock b230ft head to one that was ported and shaved to raise CR to 9.4:1, I had to pull 4deg of timing at peak torque (2deg eliminated knock, the other 2 were for safety). This was at 20psi though.

Click to expand...

I asked the tuner to build in a margin of safety. He said he tuned the spark, then backed it off a couple of degrees. The difference in HP was minuscule. I have never heard knock on the old engine, but not sure if I could with helmet on, no windows and straight pipe Miatas buzzing around me.

We don't plan on running more that 13 PSI.

Dirty Rick said:

Same cam and compression ratio?

Is it running in closed loop?

Click to expand...

I went from VX cam to IPD Turbo cam, re-shimmed. Same head, but I don't know about compression ratio. Block was decked for first time, head had been decked previously. Stock Elring HG.

I don't know about closed loop, what setting in TS is that?

Ignition table

That looks to be a very conservative spark table, I think you'll be fine.

Take the info in this thread with a grain of salt... but gives you something to compare what you have.
https://forums.turbobricks.com/showthread.php?t=346790

Thanks for the advice. I’m going to send it. What’s the worse that can happen?

Knock knock. Who’s there? Rod.