(October 14, 2013 continued)
And now I will tell you what difference this new intake has made....
All I need to say is this. The current history of boost on this engine:
- Stock: 8psi
- Performed "ABV mod": Boost increased to 8.5 psi
- New Intake: 9.75 psi to 10 psi at redline!
Yes, I'm hitting near 10 psi with all stock USDM pulleys. Stock 1988 crank pulley and stock 1988 SC12 pulley with stock 1988 SC12 Supercharger.
Power:H-U-G-E DIFFERENCE on the mid to top end. The power band kick at 3,500-ish RPM comes in much stronger now and the thing pulls stronger and stronger until you have to shift. There seems to be no top end. Power just builds all the way to redline. The first thing I noticed right away is that the rev limiter came so much quicker that I kept missing my shifts. I kept hitting rev limit.
This makes complete sense. Go back and take a look at my dyno sheet from
Reply #235 (shown below). This is at 8.5 psi. Blue line is with factory air box & filter, Red line is with the stock air filter removed from the stock air box (ie. slightly less restrictive). Just by removing only the stock filter my top end was shifted from about 6,800 rpm to about 7,300 rpm. I have not dynoed the new intake yet, but there is no doubt in my mind that power is now developed continuously all the way to peak 7,500 rpm. Whoever said the 4A-GZE shouldn't be revved to redline obviously had a restrictive intake holding them back!
Stock intake system with ABV-mod running 8.5 psiSound:Keep in mind that I've already built a 17 psi SC14-powered 4A-GZE engine (
details) so I know what these old Roots blowers sound like when you spin em up. Also I am still running stock pulleys here. So the sound is definitely not as prominent as what it could be, but I can now hear the SC really whine and it sounds wonderful! Finally starting to bring back some old memories!! It is a combination of faint SC whine + deep N/A-type intake sound from the long, straight intake setup. You get the low bellowing, throaty sound first and then you hear the SC whine come in around 3k rpm and it's just awesome. Once I change my SC pulley and up the boost, it's gonna get even better. I have to admit, having the air filter inches away from my window, I find myself driving around with my driver's side window rolled all the way down

It really sounds funny when going WOT with the S/C switched off. You get the deep bellowing intake sound but then as the Supercharger picks up speed naturally from the incoming airflow, you can hear it chopping the air and making a reverb sound. Sounds crazy and you just know that it is restricting a ton of airflow. (remember ABV is not reconnected yet)
I need to get some video of how great it sounds with the SC turned on. I will see if I can get around to this soon.
Fuel Mileage:My MPG has gone up now from 28-30 MPG to 32-34 MPG. It increased even despite having to breathe through the S/C (again ABV isn't reconnected yet). Definitely requires less throttle to maintain 70 MPH cruising on the freeway. Also I can go up the west side of highway 152's Pacheco Pass out of Los Banos, CA without using the S/C. My speed does drop on the last steep section to about 60 MPH, but before I would drop well below 60 and just hit the switch for the Supercharger. Of course I don't want to do 60 mph on the freeway, but the fact is that there is an undeniable improvement illustrating just how restrictive the stock 4A-GZE intake system truly is. Open that thing up and it will open up your world!!
Issues / TO-DO:As mentioned in previous posts, here is a list of things not currently done:
- Fix power brakes
- Reconnect Air Bypass Valve (ABV) for improved economy and performance while driving around with the S/C switched off
- Reconnect the crank-case vent (PCV) so it doesn't stink, won't drip oil everywhere, and most of all will have that leaking air correctly metered
- Install provision to get my old water-injection system hooked back up
For now this thing is GREAT! I just wanna drive it everywhere!
I've got more updates and will try to post them up soon-
Regards,
BigMike