Harrop Hurricane MAF vs Speed Density
I have an 09 Z06 E38 with a Harrop Hurricane 8 port throttle body manifold with a custom made ram air set up that brings all the air into one ram air scoop at the front of the car. It currently has a Speed Density Tune and 80Lb injectors. It has a big cam, ported heads . It puts over 600 HP to the ground, idles great, good drive ability. The car has unbelievable throttle response and is wicked fast. Perfect for the track which is why I built it.
OK now for the problem. It gets about 3 to 4 MPG (the DIC says I am getting 25 MPG remember is has 80lb injectors) on the freeway. My tuner and I are thinking about turning the MAF back on using EFI Live and trying to do a MAF tune on it to improve the mileage. The MAF is installed in the air stream after the filter before the plenum splits to go to each bank of cylinders. We are getting a good MAF reading but MAF is disabled. We want to try MAF because we believe it will be easier to tune not because we think it will get better mileage than speed density. The problem is that with 8 x 55M of air coming in the Harrop is very hard to tune. We have it dialed in on the dyno for max horsepower but we did not do anything about 1500 to 2500 RPM rage which is where normal driving occurs. So we were thinking if we use MAF up to maybe 3500 RPM or a certain amount of throttle and then go back to speed density.
So have a few questions.
1. What do you think of the idea?
2. What tables (number please or name) is it that turns the MAF back on?
3. Since the MAF airflow will be different than the stock intake what table will we need to play with to try and dial that in? The tube is bigger than the stock tube so I am anticipating it will throw off the MAF.
4. If we stay with Speed Density as I am sure many of you are going to recommend what is the best way to get it dialed in?
Thanks in advance for your help.