I am wondering because my friend has a 350 TBI truck and he plows with it. So he wants some lower end torque. He has no engine mods. Any suggestions on what to do? I assume I can't go TOO radical with the spark and fuel curves. Thanks in advance.

 

I did. In fact, I got better performance, improved drivability, better throttle response and increased my gas mileage on the highway from US 23 mpg to 30 mpg.

It's all a matter of how much time, effort and testing you do. The trick is to play with one thing at a time so you can see it's effect.

I started my eprom burning while my engine was basically stock so I could thoroughly learn how various tables work and its effect on performance, drivability and/or gas mileage. This was while I was "collecting" performance parts for my build.

I now have all the parts and I just have to get some time (and weather) to install them. It will be a Miniram, prof. ported Al L98 heads and 214/222 .488/.51x cam. I already drafted a bin based on "some theories" I've been working on. I am hoping that my BIN, while not expecting it to be perfect will be fairly close on the fuel and I'll just need to optimize the spark. If it works, I might have a method people can use to "draft" a BIN for SD cars based on specs.

 

As we all know here,the factory engine calibration is set for a broad range of elevations and driving conditions.It would cost any auto maker too much money & time to fine tune each engine.So yes fine tuning a stock engine would increase power,reduce emissions.I would think an engine would respond favorably to a " 25,000 mile prom tune up.

 

so like how much power increase can you expect?

 

Depends on if your car is running lean or really lean. Most cars like to run slightly rich but after a certain point it goes back down.
The idea is to tune the car with time and a way to measure performance. The dyno or 1/4 mile mph are the 2 best ways of going about doing this. Unfortunatly they're also the more expensive methods.
If you just data log the aldl stream and look at the o2/map/rpm/weather conditions and do a bunch of math, you can tell if the car needs more or less fuel at certain map/rpm/conditions. Timing is the same thing. Probably the best thing to do for a stock car is to play with the timing since the fuel tables are already really good. Once you get that handle on timing and where/when you need advance then you'll have a better feel for it on non-oem vehicles. I wish I had done some eproms on my old motor, instead I jumped in head first with an eprom from some cop car
It's all good though.
If you're going to pay somebody for a custom eprom for a relatively stock car I would say it's a waste. Money better spent getting into it yourself so you can burn an infinite number of eproms for the cost of one custom eprom. This way you can change things depending on YOUR style of driving and the way your car behaves.
I get back to the original point. Yes, you can make hp, probably 5hp peak on a completely stock car with timing and fuel adjustments.

 

I do a data capture with Diacom and then import the data into an Excel file to quantify changes to my eprom and ensure the changes are positive. At this time, my engine is "basically stock" (headers, exhaust and the typical freebie/cheapie mods).

I felt it was best to start burning eproms while my engine was still basically stock. I don't feel like paying some outrageous price for someone to burn me an eprom when I modify my engine (hopefully this spring/summer). I figured it was easier to learn (and quantify changes) while my car was still stock rather than trying to learn when my engine was modded.

For eprom burning you need a "reliable and quantifiable" method of quickly testing changes to your eprom. Especially since the nearest track from where I live is a couple of hunderd miles away. Others use a G-Tec, which if you use the same parameters (and stretch of deserted road) you will have a reliable method of verifying changes also. You don't care that it shows a "13.19" when it might be a real 13.55, what you want to see is if you can improve on the "13.19" repeatably. Else, how do you know if the changes you have made to your (e.g. spark tables) have done any good?

To measure the performance of my eprom changes I do a standard comparison using a 20 mph - 80 mph acceleration using my captured Diacom+ data. I chose 20 mph as my lower limit to avoid issues with wheelspin. And 80 mph is the maximum, in case I get caught I only get a speeding ticket. I like using my Diacom graphs because I can also see what's happening with my various sensor readings at certain points during the run.

I gained a consistent and repeatable .3 sec from 20-80 mph from my "best" stock eprom run to my current eprom, but I burnt over 100+ eproms on this alone - all playing with just "the spark".

I will swap my intake, heads and cam this spring/summer, but since I still have the original Memcal (I bought a spare for eprom burning), I plan to do a run at a local drag strip this year, just before I swap the parts. I will use the original eprom and then my optimized eprom to compare the differences over the full quarter - for hard numbers.

How much a person can gain really depends how much effort your put into your tuning. Don't expect to gain .3 from 20-80 mph (or over the entire 1/4) on your first couple of chips. In fact, well expect that some of the changes you intially might even make your run slower. It really comes down to your "tuning abilities" and trying to figure out what the engine wants (not what you THINK it wants).

Similar with fuel economy. Getting your fuel tables perfected is paramount for the Highway Mode to work optimally. I probably burnt another 50 BINs just on this one aspect also. Again, don't expect to increase your gas mileage 10-20% on the first couple of burns. But the more you work at, the better the results.

 

Thanks for the replies. The thing is, though, is this is for a friend and I don't want to change something to the point where it could damage the engine. So fuel and spark curves are a good way to start? How do I know at what RPM range and how much to change the values by? I don't want this to be TOTALLY trial and error. Any help would be greatly appreciated. Thanks.

 

Fuel and spark is not for beginners.If its for a friend with a stock motor don't waste your time.Yes you'll get increased hp,mpg etc,but tell him to wait for some mods.

 

Actually, it's not totally stock. He does have a full aftermarket exhaust, open air cleaner, and a hotter spark plug I believe. Thanks.