I'd say my average before was 27-28mpg, now my average is 32-33 after the HAI, but I made the HAI the day I got my SGII. I didn't want to run the HAI w/o being able to monitor IAT. So I'd say 2mpg from HAI, and probably 2 mpg from SGII/drivnig habits.
I'm ultimately wondering if the HAI is advancing my oil burn issue though. Makes no sense to me because even if the cyl. was fed w/ hot air, you'd think it would thin the oil it came in contact w/, but then again, strange things can happen inside an engine. W/ the HAI you'll for sure notice power reduction after warm up.
I tried Rislone Ring seal and it made the car run like hell, but after I changed the oil I went about 2k w/ no oil burn... then all the sudden, massive oil burn came back. I'm looking hard for an SL1 or SC1, but if I can't find one in time and get one of my other cars back on the road, I'll do a nice write up on re-ringing the S-Series DOHC for everyone to enjoy.
I'm ultimately wondering if the HAI is advancing my oil burn issue though. Makes no sense to me because even if the cyl. was fed w/ hot air, you'd think it would thin the oil it came in contact w/, but then again, strange things can happen inside an engine.
Wouldn't thinner oil be more likely to burn? I thought that putting in thicker oil reduces oil consumption...
Oops, had my logic twisted... perhaps you're right. I run 5W-30 though. I've heard it both ways that thicker oil will tend to bind up the rings and cause oil burn, just like thinner oil might make it past the rings and cause oil burn.
Anyhow, I love my S-Series, and I hope the rebuild goes well.. haha
Halfway thinking of pulling a SOHC at a junkyard and swapping it, rebuild the DOHC to gain the experience and sell it. Actually might be worth it.
I've hit 36+ MPG with my '94 SL2 automatic. But I do just about all highway driving.
Definitely do the HAI, but remember that you gotta be light on the throttle.
I used to burn 1qt of oil every 1k miles, but I found a "miracle juice" that reduced my oil consumption to less than 1qt per 3k miles (so I don't have to add oil between changes any more). If you want, I can PM you the "snake oil" but I know others will bash me and say that it never works blah blah (I have already heard this comment many times).
I have put my tire PSI about 6-8 above factory recommendation and it helps gas mileage. However it does make the ride more harsh (it is already kinda harsh IMO) and i've had to replace a strut mount already (although with 170k miles, it might have been due anyhow, but I think the higher PSI accelerated the wear).
I truely believe if I drove my car 100% highway I could average 45mpg.... I have seen as high as 47mpg on the trip home from Cleveland after fabbing the heat shield for the HAI, but after that 250 mile trip of 100% highway, I then drove all city until the tank was empty at 380 miles, mixing the mileage and ending at 38mpg.
I have 140k on my car/engine now.
REALLY REALLY considering selling for an SC1, but damn, they're nearly impossible to find!!! I'm so on the fence here. I bet it would cost $1k to rebuild, and since its my first time, it would be a 50/50 if it ran afterwards.... lol
That's a lot of risk when I could sell this for $1,500 and buy an SC1 w/ under 100k for about $4k **around here, S-Series Saturns are appreciating believe it or not**