quote:One last point of signifigance here is that with a EFI FI system, a very radical camshaft with a lot of overlap can be run on the street. That would not be so with the EFI and a common plenum. Plenum reverb in theory no longer exists with IR EFI.
You are absolutely correct. This is a point I have made before in regard to IR (and not limited to IR EFI) and attempted to make again earlier in the thread as well. I guess I just didn’t do so as well as you just did. But be advised, you can also lose the favorable affects this provides in a well engineered and highly tuned open plenum system. In practice, the latter is much harder to achieve for people (me for instance) that do not have the experience and resource of the pros. It’s also not unusual for IR systems to concede some peak horse power for the torque curves they yield. At the extreme, there can be a greater risk of fire with IR and big cams. Long duration and overlap can shove a lot of fuel out the top of the stack in certain cam profiles rpm ranges. Large fuel plumes above stacks are not an uncommon sight at the track.
quote:Since no cylinder is 100% efficient, there has got to be some unburned mixture or oil contaminant blown back into the intake system.
Sort of depends on what you mean by 100% efficient. It’s not out of the question for engines in high states of tune to show volumetric efficiencies >100% VE in their sweet spot. You know your induction is very well chosen (or perhaps the other way around) for your engine combo when this is the case.
quote:It certainly won't have the reverse venturi flow problem that the IDA's do.
Another reason why EFI and IR is especially desirable.
quote:……..I wouldn't be too surprised to find NASCAR or Prostock type cammed engines idling like a pussycat with a IR EFI.
In fact, it’s one of the most common comments from people that have run common plenum induction systems and then change nothing except to switch to IR induction. It can be pretty eye opening and really go a long way to eliminating some of the undesirable street behavior caused by cylinder communication in the plenum area outside of the optimal rpm range. Add the instrumentation, sensing, control, and programming ease of a modern ECU and it gives you a lot to fight with.[/quote]
quote:IR EFI opens up an entirely new era to radical street machines.
As I mentioned earlier, it can often be as much about who’s doing the build and tuning as what they’re building. Look at Kaase and his last EMC entry. About anything the guy touches sets the bar. For us mere mortals, I’ll take canted valve heads for their superior flow potential, IR EFI for the best street (maybe not limited to street depending upon the kind of racing we’re talking) tuning compromise, and as many cubes as I can reliably get into the build.
I just want to be clear on one more thing as well. I have not formed my opinions of IR induction based upon the desire to promote and sell systems or my intake. It's only hobby fellas. I have a day job. Others pioneered this long ago. I'm merely a disciple. Several other notable figures on this board and other forums asked me to replicate what I was doing for them. I've learned a great deal from them. I actually have far more requests IR EFI hardware than I can practically serve. The remarks that I have made are supported by my own experiences and more importantly those of others whose opinions and input I greatly value. As I have said, talented engine builders and tuners are tough to beat. I'm glad I know a few. I’d rather start with a combination that has the greatest potential.
Good luck with your EFI projects gents,
Kelly