Decisions, decisions. Supercharger or ITBs?

Keith Tanner said:

Pete Gossett said:

Toyman01 said:

In reply to Pete Gossett :

The drums get shoved out of the way when car things are happening. 

 

Then I’d suggest he needs to install the drums in the Mustang. 2-birds/1-stone and all that. 

It probably already has drums in the back. I'm not sure more drums will help :D

I have only experienced ITB's on 4AG motors, and once you get the right software to run it, they are fine.  Alpha-N is the way to go.  Speed density is a PITA, with the MAP going from like full vacuum to zero vacuum with just cracking the throttle.  Yeah, with that, altitude changes, etc., will play havoc with your tune, but with Alpha-N and baro correction, everything works great.  The factory ECU (silvertop) with a MAF doesn't have problems, but then you can't have the stacks out by themselves.

Doesn't this belong in the 1st world problems thread?

In reply to Dr. Hess :

I wonder...  Could you build big / long enough velocity stacks to stick a MAF in each stack?  Of course, getting an ECU to run that would be fun...

Toyman01 said:

In reply to pres589 (djronnebaum) :

He's pretty old school. There isn't much he likes better than polishing. It's going to stay chrome. 

Thoughts and prayers.

Dr. Hess said:

I have only experienced ITB's on 4AG motors, and once you get the right software to run it, they are fine.  Alpha-N is the way to go.  Speed density is a PITA, with the MAP going from like full vacuum to zero vacuum with just cracking the throttle.  Yeah, with that, altitude changes, etc., will play havoc with your tune, but with Alpha-N and baro correction, everything works great.  The factory ECU (silvertop) with a MAF doesn't have problems, but then you can't have the stacks out by themselves.

The E39 M5 makes them work with a plenum and a MAF as well. It's the best way, but then you lose the show factor of those unfiltered, rock-eating velocity stacks as well as cut the noise down. Takes away from the show effect. When I was running ITBs on my track Miata, I had a plenum on them. You can also solve the cold running aspect with a idle control valve sitting on a separate block attached to four vacuum lines that run into the runners post-throttle or use DBW, but the former doesn't look cool and the latter is hard. Now, what about PCV? Truth is, to do it right is messy looking.

I keep getting told how it's possible to make ITBs work with just the right software, but never actually seen it demonstrated. The reality is that very few people use them for function but are looking for show drama and peer acceptance, and the things that make them work well there interfere with the things that make them work on the road.

Decisions were made. It's coming together. There is a belt on the way and some adjustments to happen but it should be running after this weekend. 

Did he order a hood too?  Looking good!

In reply to Vigo :

He's debating on cutting the hood or ordering one pre made with a hood scoop. For now, he's going to pull it so he can test drive it. 

Supercharging it is kind of a no brainer; with moderate levels of boost there are few down sides.

initially I would have said ITBs but having read this thread I was surprised by the issues with them. It would appear that I made the assumption that they work work as flawlessly as the Keihin Flat Slide carbs on my Datsun do. Again I assumed that much like Keihins the ITBs would have phenomenal throttle response across a broad range. So clearly slide valve throttles and butterfly throttles work quite differently. This also sort of kills the any/all fuel injection is superior to any/all carbs thinking. Obviously I haven't researched ITBs beyond the they look cool stage. 

Blower > hood. 

Tom1200 said:

Supercharging it is kind of a no brainer; with moderate levels of boost there are few down sides.

initially I would have said ITBs but having read this thread I was surprised by the issues with them. It would appear that I made the assumption that they work work as flawlessly as the Keihin Flat Slide carbs on my Datsun do. Again I assumed that much like Keihins the ITBs would have phenomenal throttle response across a broad range. So clearly slide valve throttles and butterfly throttles work quite differently. This also sort of kills the any/all fuel injection is superior to any/all carbs thinking. Obviously I haven't researched ITBs beyond the they look cool stage. 

ITBs can be great.  They just require much more precision and care in their sizing and tuning.  There isn’t a lot of info available online for tuning ITBs, which is a mark against them.

its not like Weber side draft or down draft carbs are any easier to tune, but there is more info available on how to tune them available via many, many books.

In reply to Tom1200 :

Keep in mind, you could build slide throttle ITBs either from scratch or from gutting a set of carbs into just empty throttle housings.  That would get you similar behavior in theory.  

@Stefan, Flat Slide carbs are way easier and quicker to tune than DCOE carbs.

@rslifkin we've talked about simply using the flat slides as throttle plate for a fuel injection but as it's a race car there is little to be gained by going to the injection. As it also a low powered race car 99% of any given lap the motor is pulling off the main jet. The injection isn't going to make more peak power.  The races I do are done under pretty much the same weather conditions so I rarely need to change jetting. The track day events are done in weather that's 20 degrees warmer so the car is running rich but it's a track day so I don't care about the 3-4 horsepower I may be losing. 

So back on topic........I also admit to liking the supercharger whine as well.