1.8L with a goal of 40mpg

Ripper_XX · Aug 12, 2010

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kmetiuk · Aug 12, 2010

I have and arduino and the thing is sooooooooooooooooo fucking sweet. It cost $28 bucks and does 3-4 million lines of a code a second. That's lines of code not calculations. Check out their forums. It is an open source project so there is a ton of info and code out there, including OBD2 stuff.

Doesn't an SAFC piggyback the signal? Meaning that it could lean it out and tell the computer it is at stoich? I thought that was the whole idea behind them. I have never used them, but if they didn't "trick" the comp and it just readjusts the fuel to compensate for it, then what would be the point of installing one?

HAI works solely because of lowering pumping losses, the less dense air takes the exact amount of fuel that it needs to burn all the oxygen. Think of it the other way, turbo charging adds air which needs more fuel. HAI removes air and requires less fuel. The computer doesn't care what pressure or density it is at (to a point), it only cares about how much oxygen is entering the cylinder. I have taken a engineering level internal combustion engine class and have done long hand calculations (as well as computer simulations) on the effects of the throttle at different positions. At WOT the only losses are the volumetric efficiency of intake/exhaust/head which for arguments sake @2500 RPM's is say 85%. So inversely your pumping losses are 15%. Now when your cruising at part throttle at the same RPM (normal intake) your throttle is only cracked open to just allow enough air in to maintain speed. This cracked intake can be thought of as a hole with diameter of around 3/8" with pumping losses in the order of 80-90%. With the HAI, because of the much lower density of the air, the intake must be cracked further to get the same amount of oxygen to maintain the same speed. Now the hole is 1 1/2" in diameter and pumping losses are in the order of 60-70%. That extra 30% of pumping losses that was dropped is nearly directly proportional to the amount of fuel your saving. Its all about the pumping losses. The internal combustion engine is just a glorified air pump.

To add to that at such low RPM's and low-ish airflow, vaporization of the fuel is not an issue. It only becomes an issue at high RPM's where there is not enough time for it to do so. That is why on the newer Sport bikes (CBR600RR's and the like) have a secondary set of injectors further up the intake. At low RPM the primary set that is closest to the intake are used because the secondary set would have a lot of the fuel settle and wash the intake walls with fuel before it even got to the valves. High RPM has less time to vaporize and create a homogeneous mixture before it hit the valves so the engineers moved and added a second set higher up.

To maximize your fuel savings, if you could heat up the air to the point where your throttle is @ 100% when cruising your pumping losses would be @15%. I wonder how hot that would have to be, I mean the headers are probably seeing 4-600F at cruising speeds.

theblizz · Aug 13, 2010

What about a free-re flowing exhaust? I'm not saying a full 3 inch system. Maybe punch out the cat and a straight through muffler. 2.25 in/out? I'm suprised no one mentioned exhaust options in this thread. Or did I miss that?

Ripper_XX · Aug 13, 2010

Punching out the CAT rarely improves exhaust flow. It actually makes it worse. And I know your going to ask why, so i'll tell you. Do you honestly think having the exhaust expand into a chamber and then have to restrict/compress back down to the rest of the exhaust pipe size is a good thing? It's not for flow anyway. The best thing to do there is to either remove it and put a test pipe on, or a high flow CAT.

Bringing up the exhaust, I think someone did mention it's common for the NA guys to put the stock turbo exhaust on there car as a upgrade.

Project84 · Aug 13, 2010

kmetiuk said:
I have and arduino and the thing is sooooooooooooooooo fucking sweet. It cost $28 bucks and does 3-4 million lines of a code a second. That's lines of code not calculations. Check out their forums. It is an open source project so there is a ton of info and code out there, including OBD2 stuff.

......

............

To maximize your fuel savings, if you could heat up the air to the point where your throttle is @ 100% when cruising your pumping losses would be @15%. I wonder how hot that would have to be, I mean the headers are probably seeing 4-600F at cruising speeds.

At/above 170*F intake air temps the power loss is so great (in my Saturns anyway...) that I'm forced to use about 85% throttle already. It's unsafe above that level; the car just doesn't want to move. I'd estimate for comparison's sake 0-60mph at ambient temps takes 15 seconds in my DOHC model whereas 180*F intake temps 0-60mph would take 45 seconds. I've given thought to using premium fuel and adding insulation to the HAI and OEM intake baffling but the days of pioneering aren't upon me anymore. At least, I've got no motivation to go playing with things now that gas is $2.69 rather than $4.29. Call me lazy. That's why I ride a Ninja 250 to work all the time. 65 mpg and $92 insurance for a whole year.

Ripper_XX said:
Punching out the CAT rarely improves exhaust flow. It actually makes it worse. And I know your going to ask why, so i'll tell you. Do you honestly think having the exhaust expand into a chamber and then have to restrict/compress back down to the rest of the exhaust pipe size is a good thing? It's not for flow anyway. The best thing to do there is to either remove it and put a test pipe on, or a high flow CAT.

Bringing up the exhaust, I think someone did mention it's common for the NA guys to put the stock turbo exhaust on there car as a upgrade.

Yeah, OBDI cars you can remove the cat w/o any fault lights. I had forgotten that! Ooooooh, and I can weld.

Test pipe may be in order here.

I"ve given thought to replacing the exhaust manifold. I won't bother going further than that because the previous owner had new exhaust made from the header back but retained the stock cat. IDK why.

I hope to not annoy you guys with this thread. All this discussion and no testing/mods on my end yet. I started renovating my house a few weeks ago and I don't want to lose focus and start tinkering w/ the cars too much again. My master bedroom is completely dismantled. Gotta finish that first!

Project84 · Aug 30, 2010

My charging system is on the fritz!!

I'm getting battery acid spitting out from udner the fill caps on to the strut tower and my lights dim when I'm on the brakes at a stop sign/red light.

Anyone got help/info? Should I start a new thread for this?

I've read that the stock alternators are junk and did some searching here on info for the voltage regulator as well.

When I bought the car the regulator was unplugged and I wondered why... I've since plugged it back in and now I'm getting this problem. Alternator is new but I'm not sure if it's an OEM/rebuild or even off something else. That's the price you pay when you buy a used car I guess...

Snot Rocket · Aug 30, 2010

Sounds like you need a new regulator. I would guess you are over charging the battery.

Project84 · Aug 30, 2010

I hope that's all it is because that part is $42 from NAPA and a lot quicker to change than an alternator.

minstmeat · Oct 12, 2010

There was a guy who did this on a Pontiac fiero. He was getting upwards of 300 hp and 50 mpg. Shit was incredible.

cory89 · Oct 12, 2010

My dad got 36+ on my 90 eclipse base 5 speed before I bought it from him. that's stock with absolutely no mods or anything. It needs a good tune up so I'm only getting 32ish on the highway, I was also doing 90mph so.... driving conditions do make a difference.

I hope to do the same but I gotta figure out everything that needs to be done to improve mileage.

good luck to ya bro!

Project84 · Oct 13, 2010

Thanks guys. Brought this one back from the dead.

For information's sake, I did some research and it doesn't look like a 2.0L dsm alternator, or the saturn alternator upgrade, will work on a 1.8L car because of the positioning of the oil pump/filter. On the 2.0L cars the filter mounts more under the engine, on the 1.8L cars the filter mounts out under the accessory belts. The OEM alternator hardly fits without rubbing the oil filter so swapping in something that hangs any lower isn't an option. Also, the regulator, although cheap at $42, is internal and soldered on to the whatchamacallit. PITA to change, no thanks. $95 O'reilly alternator with lifetime warranty was installed instead. If you lose or break the tensioner bolt upon reinstall, steal a bolt from your hood hinges, it's the same thread and nearly the same size. Yes, that's ghetto but it worked.

I'm sorry to say the car may be leaving my posession. After the g/f decided she didn't want it unless it was "safe" and in her opinion (wtf does she know about cars???) a 1990 that has needed this much work isn't a good option. Eh, whatever.

I've got the car for sale for $1100, if someone grabs it, it's gone. If no one wants it I'll keep driving it.

I've yet to calculate any mileage due to fixing lots of odds and ends and test driving it after repairs. I've added my old lawn mower gas to the tank twice in fear of running out of fuel. Sorry no baseline numbers yet.

We'll see what comes of the sale. Like I said, if no one buys it I'll continue this project the way I intended. It's finally back on the road and the only current problems are the PS is INOP (needs the OEM hard line) and there's an axle clicking. I'm not too worried about either of those.

1.8L with a goal of 40mpg

Ripper_XX

kmetiuk

theblizz

Ripper_XX

Project84

Project84

Snot Rocket

Project84

minstmeat

cory89

Project84

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