Engine management - how, exactly, does it make more power?

I've learned quite a bit going through the process of building this engine and getting it running right. The wide band O2 sensor and gauge is interesting to watch and I actually get some information from it now beyond just having pretty light to entertain me on autocross runs.

Now, I know people make more power with after market ECUs and good tuning. I don't suggest they do not. But I don't understand where, exactly the gains come from. My '84 Toyota ECU seems to do a pretty dandy job managing fuel. 14.7 at idle, and somewhere around 11.5 or 12 at WOT. Seems like I read that's pretty good somehere.

My limited experience in tuning has been by adjusting ignition. And I have felt gains there. So I kind of suspect that's where some of the magic happen. Is that right? I'm not looking for a step by step "how to", just a general idea. Really want to talk myself into believing I can make 20% more power if I buy one of these things. I'm just not so sure without a better understanding of where the power could come from.

Street Prepare SCCA car. No internal mods. Balanced, underdrive pulleys, header. You can basically bolt anything you want to the head - intake, exhaust. No emission equipment need be there. No turbo, obviously, but otherwise, pretty much open. But stock head, valves and cam. I do have an adjustable cam gear that is legal, but no idea what to really do with it. Fiigured I'd get it in there while I was building the engine and figure it out late. 9lb Fidenza flywheel on the back.

I have parts to upgrade to '84 22RE EFI. That does control spark. I've wondered if there's a bit of a bump just in doing that. But that update will make a Megasquirt Plug N Play available.With a name like that, I'm thinking I might be able to pull that off. Then I suspect the answer is some dyno time with a good tuner. Sound right?

Any feedback would be appreciated. With the mods I've made - bigger air meter and throttle body, thinks like that, I'm pretty sure I've felt some improvement. Alll told, I'd guess In to almost 120 at the flywheel. Could be wring, but that seems a resonable guess.

So, is my thinking right? Press on and get it done, or move on to something more likely to help? That thing is a 2.4 liter truck motor.140 lb. ft. stock, and makes it everywhere. There has to be some way to leverage that in autocross (now that my tail stays planted). A little power improvement could really help. Could it get me to, say, 140 HP? 155 lb. ft. with area all over the place under the curve? Or am I hoping for too much?

Woah, my apologies for the long ramble. That's what I get for trying to post after taking my sleep meds. I dose off quietly and let you guys think on that. Sorry if it makes no sense. I'm literal having a hard time seeing what's ending up on the screen and even finding the right letters.

Good night, I think. lol

Fuel and timing. The stock computer tune is usually not very good, especially on the older stuff. Once you start modding, it rarely gets better. With a wideband 02 and MS, it can monitor your AF ratio constantly and keep it exactly where you need it. As for the timing, you can adjust it for what works best in your application, and oldr stuff usually wants more timing. You can do a lot of tuning with datalogging. It's not something I do (I'm best with a carb and mechanical advance distributor), but only because one of my buddies is a MS pro, and he does it way faster than I would ever be able to.

Your AFRs are actually pretty rich for an n/a car, at least for my tastes. I actually run in the 12.0-12.5:1 range on my turbo car.

So there's some power. Throw in some 93 octane gas and crank the timing.

You'd see big gains across the board with those two things. Of course, big is relative.

Okay, that makes sense. Kind of better control of the things I'm at least somewhat aware of. So, overall, how much difference can it make on a motor like mine?

Swank Force One wrote: So there's some power. Throw in some 93 octane gas and crank the timing. You'd see big gains across the board with those two things. Of course, big is relative.

Is it true that I could also dump in some E85 and tune for that and pick up significant power? This car is only driven to events, really. Sometimes to the garage to get work done. It's not like I'd get stranded somewhere without fuel. Though I may try to drive it to Lincoln and/or Farmington.

You'd need a pile of injector to deal with E85 because the chemical power just isn't there vs. 87 octane pump gas. And then a fuel system that's compatible with high alcohol content. And probably a bigger pump. Et cetera. Others would know more but I think I'd stick with whatever you can find in your area, I remember living there and having a "great time" finding decent octane gasoline at most stations.

I think it was Car Craft that recently played with a bunch of different fuels and tuned for each one to pull top power. Something like 101 octane Rocket Fuel gasoline was great, I think they worked up some witches brew of E85 & nitromethane was even employed and that was crazy over street tuning and 87 octane. So some 93 octane or higher octane off-highway gasoline would be great if you can tune for it.

You can apparently integrate a knock sensor into an MS2. With that, advance control over the entire rev range, and data logging you should be able to get a pretty good spark map for whatever fuel you want as long as the fuel system is also up to it.

Yeah, what they said. A standalone will allow you to dial in your ideal A/F which on a stock-ish NA motor would probably be in the 13:1 range and you could also probably lean out your cruising mix slightly and achieve better fuel mileage. You can also advance timing until you reach detonation then pull her back some, and that way your motor will be 'all it can be'. I would take a wild guess and say you're probably leaving about 10% of your power on the table.

With stock compression levels you'll only pick up negligible gains switching to E85, definitely not enough to justify your gas mileage nearly being cut in half.

E85 would allow you to run 13.5:1 compression with no ping and good timing advance. You could pick up some major power going that route. Or E85 would allow you to affix a massive hair dryer (turbo / sc) to your engine and pump as much air in as your bottom end will hold.

Thank you, everyone. You're talking me into it, which was really the whole idea.

In reply to AttoirRE:

10% would be awesome. That would be enough to make a difference. I can't do compression or blowers in Street Prepared rules. so that's out. But I am curious what "negligible gains" I could get form E85. This car sits in a garage until it gets pulled out to race, or to go work on it. So mileage isn't a real concern. It never gets more than 5 gallons put in it, and that sits for a month sometimes. If MS got me to, say 132 HP just wondering if E85 could push that closer to 140. Assuming I'm at 120ish now, that would be a significant bump uip - like 15% I dunno. One step at a time, but looks like MS will happen at some point this summer.

Thanks gang!

Ed

What an aftermarket ECU offers you is to maximize YOUR mods. To taylor ignition and fuel to YOUR mods.

The factory ECU is designed for the original specs of a stock original engine.

oldeskewltoy wrote: What an aftermarket ECU offers you is to maximize YOUR mods. To taylor ignition and fuel to YOUR mods. The factory ECU is designed for the original specs of a stock original engine.

The factory ECU is designed with a large safety margin -- they don't want to pay for warranty engine replacement even if you put in 6-month-old 83 octane and then run the AC on full blast through Death Valley in the middle of summer. :)

Getting rid of a lot of that safety margin (timing in particular) can noticably improve power. Tweaking the AFR has a less significant impact on power.

--Ian

The nomral safety margins are built both into fuelling and spark.

For fuelling- most engines (now) run rich to protect componets- exhaust manifold, valves, catalyst, O2 sensor- whatever- running rich cools the exhaust temps so that you don't have temperature problems. So keeping to 12.5:1 (on gasoline, I might add) should net you the best power, but just be aware somethings can get hot. The more modern the PCM the more close to the edge a car can run- like your Celica with a hardware based closed loop fuel and a single wire sensor will have a bigger margin of safety than a more recent car that runs with a WB sensor and has really good fuelling.

On spark- that's all about knock. Again, dpending on the age of the PCM, the adjustments will be either very general or tuned to be very specific. For instance, on your Celica, spark may be decided by running a path out in the desert for all conditions. Whereas on modern cars, you know the ambient conditions- temerature, humidity, altitude, and probably have a good guess on the octane with the knock sensor- you have a multitude of adjustments- which, again, means that you can run a lot closer to the margins.

So it very much depends on what you start with on what gains you can expect.

As for E85- while it's true that there's less energy per gallon, it's also true that you need more fuel to make best power- more enough that E85 will make a few percent more power without changing anything except running LBT vs LBT (that's Leanest for Best Torque). And even with a non modified chamber, most cars have knock issues, so with E85, you can run totally around those- a certain magazine (the name slips my mind at the moment...) did a test on fuelling alone, where a Miata was tuned just with a fuel change. The results were quite interesting.

A note about timing. What feels fast (timing advanced) is usually not producing the most HP and torque. From many dyno tuning sessions I have found that timing wants to be a bit lower than your but dyno sais. There is a sweet spot where the motor is very smooth. I would describe it as silky. Adding more timing above this point will make the car feel faster but it is not producing more hp. In fact it will be 1-3% less than the "sweet spot". The difference is usually 1-2 degrees of static timing at idle. However this can net you 1-3% more HP and torque. This is for NA cars. Forced induction is a whole different animal.

Also going standalone allows you to remove restrictive AFM type sensors found on older cars (like 90-93 Miatas), so that's another benefit, along with what has already been mentioned.

pres589 wrote: I think it was Car Craft that recently played with a bunch of different fuels and tuned for each one to pull top power. Something like 101 octane Rocket Fuel gasoline was great, I think they worked up some witches brew of E85 & nitromethane was even employed and that was crazy over street tuning and 87 octane. So some 93 octane or higher octane off-highway gasoline would be great if you can tune for it.

GRM did it a few issues ago with a Miata.

pres589 wrote: I think it was Car Craft that recently played with a bunch of different fuels and tuned for each one to pull top power. Something like 101 octane Rocket Fuel gasoline was great, I think they worked up some witches brew of E85 & nitromethane was even employed and that was crazy over street tuning and 87 octane. So some 93 octane or higher octane off-highway gasoline would be great if you can tune for it.

Actually, we'd teamed up with GRM for a similar article, where we tested out several fuels on a VVT Miata. Didn't get up to nitromethane, but we found that it didn't really perform better on race gas than on 93 octane. (87 octane did cost us power because we couldn't run all the timing that the engine needed.) A high compression, built motor would see some benefit from race gas, but our motor just had stock internals.

However, we found that E85 did give us a significant power boost, if your injectors can flow enough fuel for it (it does need more injector flow rate than gasoline). Methanol was even more effective if class rules allow it.

One other tip - we've usually found there's more power to be found in the timing map than in the fuel map. And in Street Prepared, you're allowed to remove the vane air flow meter that a 22RE would have been saddled with. Those things tend to be like a cork in the intake; removing them typically picks up around 3 to 5 hp.

I have gained 3-4whp across the board going from a "well sorted" chip setup on a MAF car to a dyno tuned Megasquirt. Little was in leaner fueling, little was in optimized timing (some less then the chip!!). You could have even better results when replacing a more archaic management system.

Depending on the engine, chamber design, and about a dozen other factors your timing may or may not be knock limited. Most multivalve, pent roof chambers are this way when running 91+ octane gas.You hit max power timing well before knock onset, and you can actually reduce power as you travel closer to the knock limit. Generally I will do dyno pulls until power peaks, or track runs, and then pull 1-2deg timing out depending on fuel used.

Also, on engines with variable valve timing, it lets you mess with those values...

One of the Porsche 924 guys in Europe found about 12hp gain going from the stock CIS system to ITB's and MegaSquirt. No other internal changes. Not bad for an otherwise unimpressive 2.0L SOHC motor.

Most of the gains were from losing the vane in the CIS system, the restrictive intake system, more finite control over the fuel and especially the ignition timing.

E85 is only worth the headaches on boosted motors or high compression NA ones. Otherwise the slight increase in power isn't worth rebuilding the entire fuel system. Also, ethanol burns differently (and cooler) than gasoline.

Can't thank you guys enough. Need to bookmark this. Great info for those of us who don't know this stuff well.

scardeal wrote: Also, on engines with variable valve timing, it lets you mess with those values...

So what do you set them at?

That's one of the problems with DIY tuning- how do you know?

A/F is easy- best power will be 12-13:1 on gas. Turn that into lambda, and then it's close enough for other fuels.

Spark- well, CA50 should be somewhere around 7 deg ATDC. More than that, and it will knock, but that's typically the spark you get MBT spark (which was alluded to before). It can be done by taking best torque spark minus 1-2 deg, which will be safe and not change best by much. Can be done on a chassis dyno, but best done on a steady state dyno. And it takes time.

Cams- that's a whole new ball of yarn to get into. How do you work out what the best cam timing is? That one, I would start with an engine model, and try some things. But setting a sweep? That's very hard to do with out some kind of decent instrumentation. Moreso, you MUST have a controller that can move it. I know MS has a plug in set up that is used (and FM has a set up that works). But it also takes some tuning hardware to do well.

You wonder why OEM's have so many dynos....

Vvt, especially actual angle control, is best done on a load dyno.