Just wondering what upgrades will offer the greatest increases in overall gas mileage for the spi. Anything will do, even the keeping the tires inflated properly jazz will work for me. Thanks in advance
In short, there is a lot you can do to increase gas mileage.
1. Increase ignition voltage or reduce resistance so more energy gets to the plugs. A more efficient ignition system will get more spark energy to the plugs and thus produce a better burn of fuel which means you can let off the throttle some to get the same power.
2. Stabilize the electrical system. An OEM electrical system can see some pretty wild fluctions depeding on load. This, above all in my opinion, is among the best things you can do. If you increase the size of the main power and ground wires, you reduce the resistance of the electrical system and with the current the typical automotive electrical system uses, any reduction can have a significant impact. Think of things such as coil packs, injectors, etc. Most injectors require a minimum of 70% of their rated voltage to work. So that means a 12v injector needs a minimum of 8.4v to just open. Increase current (amperage) availability to the injectors and they will respond quicker as well the coil packs which can increase the available engergy to the ignition system.
As well, all the sensors that need stable reference voltages to work properly. If you are in a high demand situation such as WOT, it will put a heavy load on the electrical system and with OEM wiring thing may not respond and adjust as quickly as they should and that will affect things like performance and mileage. And again, the ignition system gets particularly stressed in upper rpm range as the coil packs struggle to fire so rapidly.
3. Synthetic fluids. This should come as no surprise to anyone. Its a well documented fact that switching from conventional to synthetic fluids can increase fuel economy. In the Grand Prix I picked up 3 mpg alone by switching the motor and tranny over to synthetic fluids (Amsoil of course) and I have customers that have gotten even bigger gains than that.
4. Obviously keeping everything well maintained is a major help as well. Things like proper tire pressure and so on. Running a fuel cleaner every now and then (Amsoil just introduced a new one that I have tried and works beautifully) will help keep deposits to a minimum and will help keep things efficient.
5. Get on the highway regularly and stretch your cars legs. I cannot stress enough how important this is. When you get the car up to temperature for a sustained amount of time you burn off things like condensation in the oil, any fuel saturation and so on. All of which will not only eventually take their toll on the motor but as those things degrade the oil they cost you mileage.
I have had more than one customer come to me and express concern (particularly when they use oil analysis) that they cannot go as far as they would like between oil changes and wonder if Amsoil is really doing its job. In nearly all cases I find that they are very frequent if not exclusively short trip drivers. They get in the car, rarely let it warm a minute or so before they drive of and drive a couple miles, park for a long time and come back and do it all again. Over time this is murder for an engine, even with a synthetic motor oil.
No matter how good the engine is, some fuel gets into the oil as well condensation can cause a build up of water in the oil. But if you get on a long drive of 15 - 20 miles or so, then you get everything up to temperature and allow it to evaporate off. Fuel is particularly dangerous because it will thin out an oil like no other and in very quick fashion. Water will cause a build up of sludge over time.
So there are a few things you can do. I am of the opinion that before you modify a car, you should start by upgrading what OEM things you can. Not only will it help you maximize any gains from performance modifications but it will help extend the life of your engine.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
Yeah! Its got a supercharger
2001 Pontiac Grand Prix GTP
My Car Is The Only Whinner I Like
Where can find some aftermarket wiring that will reduce resistance? As for the coil and plug wires, I'm covered on that. Thanks for the info, it's just what i needed.
What about weight reduction? will that increase fuel mileage??
For the wiring, look for audio wire, the kind they use in the high amp audio systems, probably better known as monster wire. Or you could got to a welding supply shop, they have really good wire there, but the problem with that I believe it that it only comes in black so you'll have to use color coded electrical tape to identify the positive wires or something like that.
As for weight reduction, there are several things you can do. First, are there any unused brackets in the engine bay? The Grand Prix motor lift brackets would only get used if you were pulling the motor. I assume the Focus has a set of lift brackets. You arent using them, so take them off. On the Grand Prix its worth about 6 - 7lbs. Now that may not seem like a lot but you do that a few times and before you know it you have reduced your weight by 50lbs or so which is significan.
Furthermore, if you do all your weight reduction in the engine bay (just saying, it wont all be limited there) then that improves weight distribution and thus handling. What kind of tires are you running. Are they stock or aftermarket. The Grand Prix stock 16" wheels are made by Enkei (sp?) and are the lightest around. A lot of people at on 17", 18" and so forth and do not know the amount of weight they are adding to the car.
I spoke to a Grand Prix owner once that traded the stock 16" wheels for 20" wheels. His ET's wend from upper 14's (14.6, 14.7) to upper 15's (15.7, 15.8) just from the weight of the wheels alone. I know Dodge Charger owners that are seeing very similar things with larger wheels.
What do you carry in the trunk or hatch that you dont need. If you feel safe doing so, you can always pull the spare tire and jack. That alone is probably worth 50lbs or so. Aftermarket stereo systems are another weight hog. Those big speakers aren't light.
Can you get away with using a race battery? If so, then theres an easy 20lbs if not more you can drop. Or you could relocate it to the rear of the car for improved weight balance. If you are in a really cold prone enviroment such as in the winter, then a race battery may not be the way to go.
With the Grand Prix I can buy an aluminum engine craddle to replace the steel one and I drop some 22lbs up front. I havent done this yet, but as soon as I can get my hands on one, I will.
Basically you are looking for things that you can do without, arent necessary, arent critical and so forth. Two and three pounds here and there can add up in a hurry and before you know it, you've gained a mile or two per gallon.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
Yeah! Its got a supercharger
2001 Pontiac Grand Prix GTP
My Car Is The Only Whinner I Like
17" wheels miht be perfectly all right. Just look at their specs, especially the weight, before you buy. I have 17's on mine and they weigh less than my stock 16's including the tires.
____________________ If you can't read this, you're illiterate.
Keep the AC off as much as possible. When you're on the highway, running the AC is more efficient than driving with the windows open. When speeds are lower, the additional drag isn't much of a factor.
Also consider the cost of modding your electrical with coil packs, etc. That'll cost a small fortune that you might never make back with any increase in gas mileage. Instead of that, I'd suggest getting a set of Ford Racing 9 mm sparkplug wires. The internal combustion engine is actually a glorified air pump. The faster & easier you can get air in and out again will improve mileage as well as performance. A less restrictive air intake system will help. You can get a shorty intake for less that $100. An exhaust system will be more than that, and also adds noise. Some like that feature, some don't.
IMO/IME the most important factor of all is the driver. How, where and under what conditions you drive is critical to mileage. When you're on the interstate, how fast to you usually drive? If you're interested in mileage, stay in the right lane and keep it at 60mph or less. Got a manual tranny? Short shift it. By 30 mph you can be in 5th gear. The instant you see a red light, take your foot off the gas & coast up to it, trying to get it green. Don't be in a hurry. Try driving 2,3, or 5 mph under the speed limit. In the summer, try to run your fuel tank as empty as you dare. This is a big reduction in weight.
There are hundreds of more ideas. The most important of all is the driver.
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well then, so much good info. anyways, the only thing i really need to do is let my engine exhale, so i need some exhaust components. So i was thinking about gutting my cat. However through some research i get mixed reviews on what it does for performance. am i better off getting the off road pipe then??
oh yeah and as for the wiring, is there anywhere with a howto replace the wiring such as what we had described earlier. If so, let me know.
docinsano wrote: well then, so much good info. anyways, the only thing i really need to do is let my engine exhale, so i need some exhaust components. So i was thinking about gutting my cat. However through some research i get mixed reviews on what it does for performance. am i better off getting the off road pipe then??
Neither. Leave your cat alone, or get a high-flow cat. A cat back system with or without the hi-flo cat will work wonders. Gutting the cat, or leaving it off, or running an orp hurts all of us. We all have to breathe, and there's an excellent reason that new cars come with a cat. I don't want to come on like some kind of tree hugger, but this is something I really believe in. I'm just as much as a motor head as anyone on this site, but unless you're going to use the car exclusively for racing, please leave the cat alone.
____________________ If you can't read this, you're illiterate.
I agree with Mr. V to an extent. OEM ingnition systems are not really optimized in any sort of fashion. They are usually under powered, do not do well at higher rpms. Granted, in the higher rpm range, you arent going to be saving much if any gas, but you can at least ensure that the thing doesnt run lean.
It takes a finite amount of time for the ignition coil to saturate, fire and discharge to the plug. At higher rpm's it struggles to complete this process inbetween firings, and I think most would be surprised to find that the rpm range the coils begin to exhibit some issue with firing the plugs is not at redline either. Now, understand this issue isnt to such an extent that you're going to destroy your motor the first time you take it close to or at redline. But the fact is if you run lean, you arent running at optimum.
That all said, I have done after market ignitions on many cars and have never failed to realize an increase in power or some fuel economy increases. Does it pay for itself? Well in the end you have to figure that out yourself. Each car responds differently. There is a reason MSD is in business and successful at it. There is a reason that racers use aftermarket ignition systems. Granted, not necessarily for economy, but it is often a extra benefit.
Your plug wires alone are a huge restriction in the ignition system. OEM wires are hugely restrictive. I see/hear of people buying Ford 9mm racing wires all the time thinking that it helps out with performance. The truth is, if you measure the resistance on them, they are not really a huge improvement over stock.
When I pulled my OEM wires off the Grand Prix, I measured the shortest one (about a foot and a half or so. I'll say two feet just for good measure. I measured some 3000 ohms of resistance which works out to 1500 ohms per foot.
So I put in a set of 50 ohm per foot wires. Now that same two foot section of plug wire is 100 ohm rather than 3000. Less resistance means more power gets to the plug which in turn means a more powerful spark which means better burn of the fuel added, which means more power, or if you are at cruising speed, the computer can pull some fuel which means better economy. Add in an after market or more powerful ignition coil or system in general and you improve things further. Im getting ready to go to a 48000 volt system shortly and I have found some 25 ohm per foot wires. Still EMI suppressive so I wont get noise in the electrical system.
So, will you make the money back that you spend doing this? Well, I spent roughly $60 on the wires, the ignition coil packs will cost me about $100. So $160 for a very sizeable increase in power to the plugs which means I can either get more power (which is the intent in my case for the drag strip) or I could even open the gap up some to get more spark exposure to the fuel mixture. Stock plug gap on my car is around 0.048". I have run as high as 0.060" with my current set up. In terms of the ignition system, that is a monster gain. I typically keep it around 0.055" for some safety margin.
Furthermore, with a less restrictive ignition system I can also take advantage of the secondary firings of the ignition coils. When your plug fires, because it is primarily and inductive ignition system, it doesnt just fire and then turn off. The inductance causes the initial firing and then a set of successive pulses as the voltage decays to an unuseable level.
With OEM wires and the huge resistance they have, I am unable to 'scavenge' this additional engergy in the ingition system.
When I first got the Grand Prix it got 28 mpg all highway. I switched it over to Amsoil in the motor and tranny and it went to 31.5 mpg all highway. I then worked on the exhaust, intake and ignition system. I now can hit 34mpg and I have touched 36mpg. I now have a engine computer interface (tuner), and my last track runs show Im still running rich. Wanna guess what will happen when I lean it out some?
So, since I more frequently hit 34 mpg with my driving style that amounts to a 6mpg increase over when I bought the car. I have a 17.5 gallon tank and I have to run premium gas because of the boost. It currently runs about $2.50ish per gallon here.
17.5 X 28mpg = 490 miles per tank (assuming of course I could use every drop)
17.5 X 34mpg = 595 miles per tank
Difference = 105 miles per tank
If Im doing it correctly, you divide that by 34mpg and you get 3.088 gallons (Im sure someone will correct me if I did it wrong) and you get about $7.72 per tank savings. I run about a tank a week. I fill up on Monday and I can run all week on that until the following monday unless I have a ton of extra errands to run. So $7.72 x 4 (weeks per month) = $30.88. Multiply that by 12 and you get $370.56.
I'll let you be the judge whether or not my efforts are worth it.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
Yeah! Its got a supercharger
2001 Pontiac Grand Prix GTP
My Car Is The Only Whinner I Like
first off, headers. i notice a short supply of headers for the spi these days. Where can i get one. I know about the escort gt setup, but am looking for an alternative. Worst comes to worst, escort gt it is.
second are there any recommended performance chips or flashers out there that anyone uses and prefers to use with the spi setup??
oh yeah, also is it a good idea to open my plug gaps? Im using the screamin demon with magnecor wires. And if so how far should i open them to? stock recommends a .054" gap.
Also, my a/c is shot. would it be beneficial to bypass the a/c compressor by using a shorter drivebelt?? or would bypassing the compresser be impossible? and what about UDP's how much of a performance/economy bonus should i expect to see from one of those??
thanks for all the help so far and thanks for any further feedback.
Last edited on Sat Mar 31st, 2007 05:35 pm by docinsano
Gee, I don't know about bypassing the AC. I'd say if there's nothing else on it but the compressor, give it a try. As it is, you're spending power & friction for nothing.
____________________ If you can't read this, you're illiterate.
docinsano wrote: first off, headers. i notice a short supply of headers for the spi these days. Where can i get one. I know about the escort gt setup, but am looking for an alternative. Worst comes to worst, escort gt it is.
second are there any recommended performance chips or flashers out there that anyone uses and prefers to use with the spi setup??
oh yeah, also is it a good idea to open my plug gaps? Im using the screamin demon with magnecor wires. And if so how far should i open them to? stock recommends a .054" gap.
Also, my a/c is shot. would it be beneficial to bypass the a/c compressor by using a shorter drivebelt?? or would bypassing the compresser be impossible? and what about UDP's how much of a performance/economy bonus should i expect to see from one of those??
thanks for all the help so far and thanks for any further feedback.
On your first two points on the headers and chips, I dont know for sure, I dont have any direct experience modifying the SPI, TXFO probably would be the best source of information there.
If you are using the Screamin' Demon' set up, I believe you can open the gaps up to 0.065". However, I would stay with 0.060" just for some fudge factor. I dont remember the voltage output of that coil, but as I mentioned before, ignition systems can be stressed and finiky at higher rpms and you certainly dont want a weak spark in that range of rpms. 0.060" gap would give you the benefit of a wider gap for more flame front exposure but not a gap that is on the extreme end. On my Zetec I had the Screamin' Demon coils and wires and I left it at 0.060" gap.
It is possible to bypass the AC. The last Grand Prix I had, the compressor went out on it and so I just bought a shorter belt and ran that until I replaced the compressor.
With regards to UDP's, performance gains on a 4cyl are most likely going to be in the single digits. You're not really increasing horsepower, you are just reducing the work the engine has to do to spin the accesories, and they are typically lighter which helps. They do help with throttle response, and I dont know about fuel economy gains as I dont remember what I got with mine on the zetec. The fact is the engine is going be working a little less hard so there probably will be a little I just dont know how much.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
Yeah! Its got a supercharger
2001 Pontiac Grand Prix GTP
My Car Is The Only Whinner I Like
I thought I would add another point to the reason you want to stay on the safer side of your plug gap.
The Ford Focus run unaturally lean, it is nearly exclusive to the Focus too. It is beyond me why Ford set the fueling they way they did for the Focus, at least the Zetec DOHC motor, but its definitely another reason you'd be better off staying with 0.060" on the gap.
If someone could hook up a tuner to the Focus Id bet there would be some power gains to be had by correcting the ridiculously lean fueling Ford set for the Focus. I would much rather be a little rich on fueling than as lean as Ford tuned the Focus.
Im not sure if the SPI is set the same way, I can only assume it is at this point.
____________________ My car is a synner! It uses Amsoil Synthetic Lubricants.
Yeah! Its got a supercharger
2001 Pontiac Grand Prix GTP
My Car Is The Only Whinner I Like
IMO/IME UDP's are the single best "bang for the buck" mod that you can do for the Focus. For the money spent, nothing else will increase performance that much. What it'll do for mileage I'm not sure, but it probably wouldn't hurt.
____________________ If you can't read this, you're illiterate.
Is there anything you can do with the airbox to increase flow? I have been looking for some aftermarket CAIs for the SPI but all I can find are ZTech and I don't know how well those fit on SPIs. If so where can I get one. I have heard talk of a shorty intake, but the problem is the car is leased and I have to be able to return it to stock in case I have to take it in for repairs. I'm going to keep it at the end of the lease but I want to be able to return it to stock just in case. Thanks
