Trying out Miata TBI on a FFS supercharger. After years of tuning, this is a first.

 

Are you using staged injection?

 

So it's just as stupid now as it was decades ago? Can't say I'm surprised

 

No, since staged injection would require me to wire 2-4 outputs all to one injector, or else it would only fire 1/4 time I'd want it to, ain't nobody got time for that. Although if this doesn't work out I'll find some time.

Yes. I think I'll tune the FF630s without any 5th injector, then add it in to see how well it cools AITs (GM sensor installed in plenum, and adjust from there. It's something like a 2000cc injector, so right now my range is 35-37% DC between too much and no difference. I'm guessing my frequency is the cause of this.

 

So it runs at a fixed dutycycle? Would one of the generic PWMs work? I wouldn't imagine that it needs to be timed with the intake event.

 

I'm using the 3d boost duty table, so fixed for any given rpm/throttle. Generic PWM would be the same, although it would allow me to change the load axis. Doesn't need to be timed to intake event, it'll explode when the valves are closed and the plug fires. Good enough for GM, good enough for me.

 

I certainly wouldn't want to give up a boost table, we are already 1 short AFAIAC. Not being able to do a proper boost by gear and flex blend at the same time is a PITA.

GL man!

 

Car is not/will not be using flex fuel, nor can I control boost AFAIK (SC), and it'll make 180, maybe 200whp (I'll post a dyno sheet eventually), so boost by gear...not necessary.

 

I have an SC and control boost

 

Slightly different setup

 

Just returned from the dyno, made 188hp with MATs hitting ~200 by redline. The “e-cool” injector did nothing for boost or power or MATs, and was disabled. The biggest help was making a non-corrugated intake tube, which made 17 extra ponies.



we did try every variant of filter/no filter, maf/no maf, tube/no tube, and it was definitely the tube destroying all flow.

 

So ecool did nothing for MAT? This is a belief I have had for ages but have never had (or looked) for data to support. Thanks for the update!

 

I’ll post some logs, but as far as I could see, no it did nothing. I tuned it for 11.2-11.6 from 1500-7400rpm. With flow force’s 650s, they performed beautifully. Every pull would go from mid 140s to high 190s MAT. Added enough 5th injector so the entire AFR curve was .5-.75 points richer, even after taking 10% fuel out of the port injection. MATs we’re still going 140s to 190s. I could have continued to add more, but wasn’t interested in actually turning it into a TBI car. This is also 40s ambient, i shudder to think what it’d do on hot summer day. It’s really quick to recover with cold air blowing on it now.

its not my cup of tea, hence my thousands of posts on MT.net and not MSC.net, but it’s still fun, especially lower RPM. More torque than a turbo briefly until it turns more into a rotrex power band feeling. But my biggest complaint is that intake. I’m more disappointed it’s sold with that then the 5th injector black magic.

 

Curly, would you share the dyno plot, please ?

 

Yes, superchargers definitely have their advantages, but don't tell anybody around here... they might get upset. The PD SC is actually making quite a comeback, especially in the UK.

Seriously though, nobody who buys and installs one of these kits actually uses that tube do they? Even the most nooby-noob-newbaru should be able to look at that thing and know it is rubbish. It looks like what I use on my downspouts.

 

You obviously haven't interacted with the kind of people that buy FFS supercharger kits.

 

Here's snap shots of the datalogs for now, I'll have the dyno plots soon. First is with E-cool providing around 10-15% of the fueling for the car. MAT starts at 142, climbs to 183 by redline, 190 max before beginning to drop off after the run



Next is a run soon after, I basically waited a minute or two until MATs were back down to the 140s. MAT starts at 142, and hit 187 by redline, nearly 195 before cooling back off. Yes, that's roughly a 4 degree increase, however that 2% difference was not significant enough to warrant continued tuning on the 5th injector. MATs are still wildly out of control, and require significant changes in intake cooling, not a 5th injector.

 

In contrast, here is another car I dyno'd recently. BP4W EFR 6278, making 260hp. MATs climbed from barely above ambient to a peak of 113, 4 minutes after the previous run. This was the 22nd redline pull of the day, which took an hour.

The two supercharged datalogs I posted above, were the 11th and 12th pull of the day, and taken 5 minutes apart.

 

What was the Ambient on the EFR run? Stated another way, what the the total rise over Ambient at 260 WHP?

I think the low MAT reading is about 55F, but I find it hard to read. That would mean about 60*F Rise in a virtual steady state condition?

 

Ambient for the EFR car was probably 40-50. Yes, low MAT was 55. AIT is in the intercooler end tank IIRC, don’t recall if it was a decent intercooler or not.