seanof30306

My thoughts on laying out the parameters for a hypermiler engine: 1) If you look on fueleconomy.org, and compare different models, you see that 4 valve per cylinder, DOHC, VTEC, etc models tend to get worse MPG than their lower-tech counterparts. I don't know that there's anything inherently less efficient in those technologies, I'd tend to think they'd be more efficient, and therefore, should get better mileage. The thing is, those technologies were designed for performance, and would likely be employed in engines with higher compression, more aggressively cammed, etc., as well as put in cars with stiffer gearing, more performance accessories, etc. 2) Fuel injection is way preferrable to carbs when it comes to MPG. All fuel injection is not created equal, though. Throttle body injection (TBI) is sort of the red-headed stepchild of fuel injection. All it really is is a carb with more precise fuel metering. The fact that it mixes the air and fuel in the intake means it has all the inherent weakness of wet-flow systems. Believe me, if my Firebird hadn't come with TBI, I never would've messed with it. Direct port injection is much more efficient. The fuel injector is placed right at the intake port on the cylinder, so there is no pooling. Even better yet is sequential fire direct port injection, where the fuel injector meters the fuel with incredible precision, introducing it only at a very specific point during the intake stroke. But wait, there's more. MAF (Mass Air Flow) injection determines how much fuel to add to reach a pre-determined air/fuel ratio by actually sampling the air. MAP (Manifold Absolute Pressure) works sort of like a blind man who has memorized the route to work. The amount of fuel is determined by engine vacuum. The problem with that is, if you make any changes in airflow (free-er flowing exhaust, intake ari, etc., the MAP system can't make adjustment, all it can do is follow it's fuel tables, as dictated by engine vacuum. Furthermore, if you change camshafts, you can throw the system totally out of whack. More duration means less vacuum, which MAP fuel injection interprets as the throttle being opened further. You can be sitting at a stoplight and it thinks you're running down the road at 40 mph. MAP is also very vulnerable to vacuum leaks, etc. MAF is a much better way to go. So, for our theoretical Hyper-Z, I'm thinking the ideal induction system would be a Mass Air Flow, Direct Port, Sequential fuel injection system. Preferably, it would be an OBDII system, as the pcms are faster (and therefore more agile), and they are much easier to hack and tune, and you can often use wideband O2 sensors, which makes your tuning much more precise. As far as the engine itself, that's a little more complicated. If we were looking 100% for economy, we would go with the smallest displacement, simplest, lowest hp engine possible. An 80hp Z-car, though, is kinda sacrilidge. I'm not sure where the right compromise is. I'd think that's going to be pretty individual of a choice.

Kiwi's SR20DE suggestion is interesting, especially if you could mount it using the cradles for the SR20DETs.

I don't think it's a question of "fail", or "pass". People on this site, for the most part, own their Z-cars as a hobby. No matter what they're doing with them (top end, 1/4 mile, road race, autocross, etc., there are generally better choices. people modify Z-cars for those purposes because they like Z-cars. This is no different. Sure, I could buy a CRX HF, or Yaris ..... but, I'd have a CRX or a Yaris, not a Z-car. Modifying an S30 for hypermiling is just another direction for these awesome cars to go in. It doesn't mean the Z-car will be the best hypermiling car there is, it means you can hypermile, and still drive a Z-car!

I'm sorry that happened to you, but that is an extremely unlikely scenario. I used to have a girlfriend who had been struck by lightning out on a golf course on a clear day. She lived, but her parents didn't. Does that mean I should never go on a golf course again? When warm, my bike starts in less than a single revolution of the engine. Sitting at a traffic light with my thumb over the start button, I'm confident I can start the engine in time to react to virtually any situation that comes up. Regardless, this thread was created to discuss possible engine choices for a hypermiler Z, not to debate the safety of various hypermiling driving techniques. Please don't hijack the thread.

I think it is a learned thing, and you should see results in any car. I've had my Jeep for 12 years, and never got better than 16-17 mpg. Just changing my driving techniques puts me consistently in the low 20s. It is really hard to do at first. Especially slowing down on the highway. After you get used to it, though, it's no problem. To me, it's actually kinda fun. I'm way more engaged in the process of driving than I used to be. I'm paying more attention to the road ahead of me and the traffic around me. The batteries just aren't there for electric conversions yet. What we need is Doc's Mr. Fusion. I'm thinking a z-car might make a good candidate for this because it's light, roomy, and most importantly, cool. I'm a car guy. Just because I'm rechannelling my interests towards economy doesn't change the fact that I want my baby to look good and excite me. I managed to establish the fact that I have a large penis a long time ago, and no longer need to run sub 12 second quarter miles or do burnouts at the Sonic to impress the laaaadies. Bringing a S30 hypermiler in at 2400 lbs, or less, with 150 rwhp and 30+ mpg while still being able to bend a few corners at the autocross would be pretty cool.

I understand that. There's a huge difference between 15.7:1 and 19-20:1, though, especially in cars with older, slower pcms. I'm getting over 400 RWHP out of a 383 GM TBI on 87 octane gas. it's taken years of tuning to get there, and I never could have done it without the embedded lockers emulator. I've created literally dozens of fuel tables, but the slow OBD1 processor is not agile, and, after watching people kill their engines from catastrophic detonation, I don't ever go past 17:1 in my lean cruise tables. I still get better highway MPG now than I did with the stock 305. When you're cruising down the highway at 1700 rpm with your fuel tables leaned out to 20:1, something as simple as a severe wind gust or a slight hill can immediately put you into catastrophic detonation. Even LS1 guys, with much faster PCMs, run into this problem. The further you lean it out, the more vulnerable you are. That's why OEMs tend to tune fat. They're building in a cushion to avoid all the warranty claims. Then there's the gas. Stoich for gasoline is 15.7:1. Start adding in ethanol, though, and Stoich gets progressively fatter. In my state, they can add up to 10% ethanol without having to disclose it. A few months ago, I noticed the mpg on my Jeep fell off about 2 mpg. Drove myself crazy looking for the problem till I found out they were selling a 9% ethanol blend. If I had a superlean tune on my car and put that fuel in it, I'd overwhelm the knock sensors and damage the engine withing a hundred miles.

Hold on, dude. That is getting a little shrill. I've been riding since I was 15 years old. Everything from motocross to road racing. In virtually every situation in which someone driving for economy would find himself shutting off the engine in order to save gas, there is absolutely no danger is auto-stopping. Sure, if you want to roll up on a 70 degree+ turn at 80 mph, it'd be dangerous to go into that corner with the engine dead (although anyone who doesn't have sissy stripes on his tires could handle it), but hypermilers drive slowly. for the most part. The situations where they auto stop are entirely different. More importantly, the technique is called "auto stop" for a reason. Here's a typical auto stop situation: I'm driving down a surface street at 35 mph. 200 yards ahead of me, a light goes red, so I pull in the clutch and shut off the engine, coasting up to the light. Absolutely, positively nothing unsafe about it. Here's another scenario. I'm driving to work in the slow lane on a multi-lane highway at 60 mph (speed limit 65). I crest the long hill leading up to my 15 degree exit. I check my mirrors to make sure no one is following closely, pull the clutch in, shut the engine off and coast down the hill. By the time I reach the exit, I'm at 55. I continue to coast up to the long red light and sit there, with the engine off, till it goes green. Absolutely nothing unsafe about it. I totally agree that hypermiling can be dangerous if done improperly. I was horrified when the guy who showed me the techniques ran a red light and took a 90 degree corner at 45 mph just because he hates kinetic braking loss. Later the guy pulled his Insight within 3 feet of an 18-wheeler's trailer, shut the engine off and drafted down the highway, proud as he could be! You can't compare every performance enthusiast on this site to the few extremists who go out and tear up the roads. You can't compare every motorcyclist to the manic who rides a wheelie down the highway at 80mph. Don't compare every hypermiler with the few extremists who take it to an unsafe extreme.

Here's the thing ... why can't someone make one of those econoboxes look cool? They's sell a lot more of them over here if they didn't look like dorkmobiles. A buddy of mine is obsessed with the Smart Car. I think it's a pretty good idea, except it gets 20mpg less than it should, for what you give up. 40mpg, for that? Give me a break. I'll take my old CRX HF .... 50 mpg all day long. What I'm trying to do here is take my project car, and instead of striving for max hp/tire frying/little old lady scaring, striving for mpg. My daily rider will be a motorcycle, and I'll keep my jeep till the wheels fall off. This is just the thing I tinker with.

The higher gas goes, the younger and hotter that little old lady seems.

I agree on the brakes. On a non-power brake/power-steering car, though, there's nothing at all wrong or dangerous with the auto-stop technique. I do it all the time on my bike and it is 100% safe. As far as lean-tuning, that can get very dangerous. You can lean an engine well past Stoich, and it'll run great on a flat road, but run into even a slight uphill, or romp on the gas by accident or in an emergency, and you can find yourself with catastrophic detonation. I've been fooling around with my GM TBI Firebird for a number of years. The forum I belong to has an avid group of tuners who have long-since hacked the ECM's and began burning their own chips. In the past several years, we've moved beyond chip burning to emulators, wideband, and on the fly tuning. My TBI originally had 3 fuel maps; it now has 24, and more timing tables than you can shake a stick at. Recently, a couple of guys have gotten greedy, taking their "economy modes" into the stratosphere, and they've done a lot of damage. Even though they have multiple tables, those 20 year old OBD1 ecm's just aren't agile enough to react in time when you rolling along at 19:1 and hit a hill.

I really like fuel injection for the mpg and reliability, but am a little afraid of it for hypermiling. One of the techniques they use is called "auto-stop", where you coast with the engine off. One of the reasons I like the S30 is no power brakes or power steering, which lets you auto-stop safely. As I was studying the different techniques, I experimented on my Jeep Cherokee. On my way in to work, there a downhill that runs for almost a mile and a half, right into the highway exit. I found that I could crest the hill, throw it into neutral and shut it off and coast all the way to the light, shedding only 5mph or so before getting to the exit. Soon after I started doing it, though I started having problems with the Jeep. Under normal highway driving, the converter would intermittently lock and unlock. Also, while it starts perfectly when cold, if it's been running even a few minutes, and you shut it off, it won't restart unless you floor the gas. Kinda kills the whole idea of coasting. I reset the PCM, and the problem with the converter cleared right up. Haven't solved the restart problem, though, and no one on the Jeep Cherokee forum or the Hypermiling forum I'm on has any clue. It's made me wary of hypermiling a car with a VSS, which is the only thing I can figure auto-stopping would affect. Here's the clean mpg forum, if anyone's interested. http://www.cleanmpg.com/cmps_index.php Over the past few months, I've transitioned to my '79 Kawasaki KZ650 as daily transportation. It got 36-37 mpg, but, using hypermiling techniques, I've been getting 44-45, and the jetting is still too rich; there's a lot more there. Oh, and on your hypermiling experiment? The biggest gains I've seen came from simply slowing down. I normally drove 75-80 on the highway. it took some work, but I've managed to slow it down to 60. You never realize how many crazy people there are on the road till you quit passing them. Last summer, I had to make a 206 mile round trip several times in the same week. I decided to run it late at night, and to set the cruise on a specific speed each time and leave it there. Here's what i got. 50 mph: 25.21 55 mph: 23.89 60 mph: 22.46 65 mph: 21.33 70 mph: 18.87 The next biggest gains came from retraining to eliminate jackrabbit starts, and shutting it off at stoplights, drive-throughs, etc.

For the past year, or so, I've been working at rechanneling my aggressive instincts away from going fast and towards economy. Surprisingly, it's worked, at least, for me. Going slower, relearning how to drive, etc. drove me crazy, at first, but once I learned the techniques of hypermiling, it actually got interesting as i worked to do better and better at it. In order to hypermile, you have to be a lot more engaged in the process of driving; you can't just crank up the stereo and kick back anymore. In my Jeep Cherokee daily driver, I've gone from 15-16 mpg to 22-23 mpg simply by changing the way I drive. That's not a lot, but I think it's pretty good for a 3900lb brick. In recent months, I've begun riding my old Kawasaki KZ650 as a daily rider. Applying hypermiling techniques has taken me from 34-35 mpg to 47-48 mpg. I've been planning on selling my '89 Firebird toy for awhile and replacing it with a 240Z for some time. I've always loved the way they look, and I fit better in a Z than any other sports car (6'5", 260). I'd originally thought about an LSX swap, but, I've recently realized it'd make a great hypermiler candidate, too. It's light, it's aerodynamic, it has manual steering and brakes, and there's plenty of room under the hood for any engine I'd want to swap in. I'm thinking I'd want to swap in a non-turbo, 4 cyl gas engine with at least a 5 speed transmission (preferrably a 6 speed). Obviously, fuel injection would be preferrable, but I've run into problems with the PCM from hypermiling my Jeep, I think it's related to engine-off coasting and the VSS. I'm just wondering if anyone else has thought or done anything along these lines.

Did a search, can't find anything on those flares. Do you have a link?