Looking for some advice for street tuning a B20VTEC on 93 octane (Always open loop). I have some experience with tuning Nissans and their MAF systems, however, the Honda ignition and fuelling system (MAP) appears to be slightly different to what I use (Nistune). I have a wideband setup and also have knock detection gear, running a chipped ecu with CROME PRO.

The motor:

B20B JDM block
YCP 84mm pistons
Stock rods
ARP Rod bolts
Modified OEM headgasket
JDM 96 spec ITR cams w/ stock cam gears
390cc JDM 4G92 GSR injectors
190LPH Walbro w/ stock regulator
4-1 ITR replica header
2.5" full mandrel custom exhaust

Assumed compression 11.6:1 - 11.7:1

Based on research

- I am aware that a relatively high compression build like this requires less timing in high load low rpm areas (Have retarded timing on where I would assume the engine will be leaving a set of traffic lights with 30-50% throttle)
- The P30 map is a relatively good map to start with and is rarely altered as the low load/cruise cells work quite well.
- Run a lot less timing in the overall map (3-4 degrees overall for safety margin)
- Tune for 14.7-15.5 in low load cruise cells
- Tune for 13.0-13.2:11 in WOT (rather than 13.7:1 as compression is higher)
- MBT occurs 200-300rpm after peak fuel consumption

Have a few questions for those who are experienced in tuning these setups.

1. I have quickly whipped up a base map and was wondering if this would be safe to run? (Attached below)




2. Excessive timing between gearshifts can potentially cause pressure spikes = motor explode? (Quoting Uncle Dave) - How can this be prevented?



3. When tuning cruise cells, should the car buck whilst in 15:1 AFRs, do I remove timing in the particular area and smooth according?

4. When tuning VTEC, will the maps above suffice for getting the AFR's correct prior to adjusting timing?

5. After MBT, a small amount of timing can be added to maintain torque curve - How much does one usually get away with adding?

Any other advice would be greatly appreciated

 

That I am aware of most MAF systems still utilize a MAP sensor. The OBD-1 tuning platform is a Speed Density system and not a "MAP system" (although yes, it does use a MAP sensor).

Your "assumed compression" isn't considered high these days; this is especially true for N/A builds. You have 93 octane, you are fine.

CROME adds quite a bit of timing as it is. Honestly, you couldn't have picked a worse OBD-1 tuning option. The random glitching sure gets old, and it forces you to continously reverify things.

Not all engines will want to be ran lean. This is the whole reason for having a tunable EMS in the first place. Basically finding out exactly what each engine wants will only come with experience. From how it feels, sounds, and the way the maps shape up, etc...

For your specific CROME questions, I would get ahold of VegasInvasion on here. He is the resident CROME expert who tunes it every day. He also is the one who made the CROME tuning manual. I am just a simple tuning hobbiest who has yet to blow one of my own motors from my tunes.

 

you've got me beat, i lost a motor back in 2005 i had a boost spike and no boost cut set in uberdata. only one ive blown from my tuning....

those timing maps dont look half bad. i may bring my peak timing at low load down to around 38-40 degrees, bring the timing in column 8 on the hi cam map down a bit in case the ecu brings in that column for interpolation while you are at wot you dont want it to jump the timing a few degrees. i also may keep the timing in column 9 from about 6500 rpm up around 25-26 degrees as a safe starting point until you can get it dyno tuned. you may want your afr to be more into the mid 12s at wot instead of low 13's but these are all things that can vary and really are ironed out during tuning. having a form of knock detection like knocksense etc wouldnt hurt. i would see what others including vegasinvasion have to say, i just do this stuff as a hobby