Easy/cheap ways to improve low end torque?
 

I read about advancing (or is it retarding?) the timing 1-2° but does that really help? I have a friend that would be willing to do it for free and then change it back for smog. Also, would tuning the ECU help? With that being said, would advancing/retarding timing effect mpg at 65mph?

I advanced my ignition and cam timing. And also increased valve lash. I guess there could be more cam wear, but I have plenty of extra camshafts. The big difference, while not as easy, was the 8-valve conversion.

Advancing can increase nox due to slightly increased cylinder pressures. This increase is also why most 80-90's car can benefit from some advancing (were retarded relative to ideal from the factory).
Can it improve your car? Depends. A D15z1 is advanced about 4 deg from the factory relative to all the others, and is why it has different timing marks. I have tried advancing and retarding it in 1 degree increments (-4/+4), nothing was better than factory. You would have to look at your car to tell.

If you're looking for low end, cut weight. Either from the engine, or chassis. Gearing will help too, but is just done off of the final drive will hurt highway mpg. There are other ways, but they can be hit/miss and not easy or cheap.

Well I have a VX tranny in my HX so I like the tall gearing, I just wanted a little more torque so when I take off I don't take off like a snail.

I'd just rev it up a bit more. If you look at the BSFC maps, there isn't a huge penalty for going to higher rpms (vs lower load).

I'm with Daox, don't try to increase the torque. If you advance your camshaft, you gain low end torque but you also lose part throttle efficiency.

This is the cheapest and easiest way to increase torque...

No wonder 8-valve engines are still popular back here :D

I've read somewhere that longer intake mainfold will increase low end torque but you'll suffer in terms of high end power. But to build a mainfold is not cheap or easy anyway :)

I did A-B-A testing and I actually gained 1-2 mpg going up to 3k RPM then shifting vs 2,250. Idk. It's the same street and I have repeated the test about 10-15 times within 1mpg difference so yea. I have been shifting at 2750-3k recently.

Changing your launching rpm is one way to increase torque and how fast you accelerate and your shifting rpms. My sidekick I release the clutch at 3 grand and shift at 5500. First gear is soo low it just takes off vs squeal. Im sure there is a bit more wear than using a lower rpms, but I want a better clutch anyway. :thumbup:

A "little" more wear? 3000 vs. 0 rpm is a lot more wear. For my hybrid I take off as close to 800 rpm as possible, to minimize clutch wear. The electric motor provides the torque. My Honda Insight with it 11.5:1 compression ratio does this automatically. All I have to do is run octane 91 gasoline (which would be considered 'standard' in Europe).

Many modern cars do the same thing. I just saw an interview with a Ford engineer where he says their engines detect higher octane mixes & advance the timing to increase MPG.

The new 13:1 Mazda engine runs okay on subpar 87 but advances the timing on 91 octane. (In Europe Mazda increases to 14:1 ratio, and recommends 95 octane.)

Baltothewolf, the cam timing or valve grind kind of determines where the power or torque is. The VVT, VTEC, etc helps to extend the torque or power band to cover a wider range.

Many geo, suzuki owners use a cam wheel to offset the cam timing to lower the power band. The Geo metro xfi infact came with an offset to do just that to make better use of the higher gearing.

You can find plenty of cam wheels on ebay for the older hondas and try advancing it between 3-10 degrees.

If you got a Honda with the IMA, it gives 100% torque just above idle, then it falls off as rpms climb. If you get a change to drive a gen 1 insight or stick shift crz you will see what I mean. You can easily, effortlessly shift it to 6th gear to 25 mph and accelerate slightly. Once you get past 2 thousand rpms the acceleration drops off.

Alfa on their two litre 16 valve twin cam had a variorator which chsnged the length of inlet manifold to deliver a flat power curve. at 4000 rpm it switched a flap then took off again. 0-60 7 secs 135mph topend and an easy 40mpg if driven within speed limits. loved mine until 150k miles and immboliser probs made cost effective repairs a non starter. £1000 to sort imobilelizer out £300 for new clutch timing belt £500+. List goes on car was worth less than £3k.

That reminds me a lot of the variable intake runners on some 90's Toyota's. The 5E-FHE engine had one.

Actually, they use a different octane scale. (RON, as opposed to AKI.) So their 91 is basically our 87.


A number of cars over the years have used variable-length intake manifolds--most of them done by having a butterfly valve that closes off a longer section, or opens up a resonating chamber. I recall that some later Honda Preludes did, as well as the aforementioned Alfas and Toyotas, some Porsches, and some of the more exotic Italian metal. I'm sure others have also had some way of either making the path longer or making the air "think" it was longer.

A very, very few have used variable-length exhaust manifolds. I think it's too expensive to make articulating bits that will hold up over the long term under the high heat and moisture content of exhaust gases.

-soD

I'm not entirely clear on this. There are some over on InsightCentral who claim going above AKI 87 yields no benefits in the G1 Insight. I've actually returned better numbers filling up with 87 than with 93, but basically within margin of error.

@Balto, I'd experiment with advancing timing. Even if you do lose a bit of part-throttle effiency, with your gearing you're probably able to maintain very high loads at any reasonable speed.

I can say the gen 2 is similar. With between 89 and 91 you get better mpg, but its not cost effective. If you keep your foot in it and have a cvt, it has more guts so to speak in regards to how it varies the rpms and acceleration.

93 is another story. Many cases you arent getting true 93 and when you fill up it adds to the fuel already there and becomes less than 93 octane. After a few tanks of 93 I started to loose throttle response like on the 87 stuff. I then backed down to 91 octane.

Variable exhaust:

https://www.youtube.com/watch?v=VN3bFiwQMos

A more sophisticated version is used by Ferrari. Waaay more sophisticated :D

Thanks for all the help guys, but I think I'll just continue shifting at 2750-3k RPM. I had no idea how effective it would be and quite frankly I'm amazed. I don't always shift at those RPM ranges but when I'm Highway driving I do. First gear is 3k, second is 2750 and 3rd is 2750 then 4th to 5th is either 2500 or 2750 depending on wether I'm going to drove at 55 or 65. Seems to work pretty well.

Thats the first thing I did when I got my sg2 was search for shift points, then the overall crusing speed'gear'rpm combination. :thumbup:

I was looking at increasing low end torque on my Honda as well. My transmission is shot so I'm replacing it with the a000 which drops my hiway rpms quite a bit and I was wondering if my d16y8 would make enough low end power to still be efficient at the lower rpms. I believe the new hiway rpm would be around 2200. Instead of the 2700~2800

I expect you'll be fine. You may need to downshift for some hills, but you'll be able to maintain speed.

Remember, the more open your throttle is, the better. Part throttle is less efficient.

Really? I didn't know that. How does that work? Because with the throttle open more doesn't that mean more fuel? Usually when I'm trying to get higher mpgs I figured that having the highest vacuum would be the most fuel effiecnt which occurs at a midrange rpm and less throttle. Is this just on maintaining speed or is this for acceleration as well? Teach! ��

Here's a base-specific fuel consumption chart for a Prius engine:

http://ecomodder.com/wiki/images/thu...prius_bsfc.jpg

Here's one for a more traditional Saturn engine:

http://ecomodder.com/wiki/images/thu...FC_cleaned.png

Source: http://ecomodder.com/wiki/index.php/...on_(BSFC)_Maps


In brief, higher cylinder pressures are more efficient, and generating vacuum wastes energy. There's also a best RPM for each engine geometry, which has a lot of factors but probably has a lot to do with flame speed vs piston speed and the fact that friction goes up exponentially as RPM increases.

In a perfect world, an engine would be able to operate at its best RPM and generate no wasteful vacuum. Unfortunately, the power needed in a car is highly variable, while engines are only efficient in narrow windows. Engine sizing, then, is very important.

In a vehicle with fixed ratios, increasing vacuum does indeed reduce the fuel burned, but you're also losing efficiency. It would be better, rather than running at higher vacuum, to have a yet taller gear and keep vacuum low. After all, doesn't upshifting always hurt economy? And downshifting help? But it reduces vacuum? If high vacuum we're good, you'd always want to drive around in first gear at redline to make the most vacuum possible.

In something like a Prius, where engine speed can vary effectively infinitely, the throttle plate is left wide open and engine speed is varied to produce the power needed to move down the road. Diesels are more efficient in part because they generate no vacuum, but instead have a variable air:fuel ratio.

Many engines start to enrich AFR near wide open throttle, which is a large part of why peak efficiency is often just below that, rather than at it.

Systems like variable valve timing and cam lobe profiles are examples of technologies which make the high efficiency windows larger.

If you wanted to run your engine at high load all the time with fixed gear ratios, you would, unfortunately, accelerate past the speed limits, because most engines are oversized so you can still climb hills and such. Many on here practice a technique called "pulse and glide", whereby they accelerate, then cut power to the engine and coast for a bit. This isn't always feasible, but it usually provides large returns. My previous car had stupid gearing and would deliver ~30mpg at 45mph, but could average over 50mpg with very dedicated pulse and glide averaging the same speed.

Hybrids oversize the engines less and provide burst acceleration assistance with an electric motor. My Insight's gasoline engine actually varies air:fuel ratios too, to a limited degree, which allows diesel-like efficiency in some cases. Hybrids also get rid of a lot of lossy accessories; my car has no power steering pump or alternator. For these reasons (and more) I can see 100-120mpg under optimal conditions, without the need for many driving techniques. For you, there are a lot of tricks you can use to overcome engineering limitations and improve economy. Driver technique often provides more return than any modification to the car.

It's kinda late. Somewhat pick up what you're saying. Is this kinda how lean burn works? Less fuel and less power so you have to give it more throttle which in turn increases your throttle efficiency? Is that along the lines of the same concept? Cause I get the throttle efficiency because more vacuum the more your piston has to work to draw in air.

This is probably why egr works because it's an inert gas. So the more inert gas the more your throttle opens. That makes sense. But I still hate it. I don't like egr at all. My brain is going to town with appifanies right now. It's all making sense.

That's exactly right.

What's wrong with EGR?

The only thing wrong with ERG is people not understanding what it does :)

I don't know. I'm still pretty young and inexperienced. But everytime I've deleted the egr my engine has stayed cleaner and my mileage has increased. On my 87 Nissan I'm not sure how much it increased but doing the delete on my xterra gave me an extra 3 mpg. Now that I have this untampered Honda and a little more knowledge and experience I can do some more testing. But I understand your theory. From what I've read egr is just to decrease compression temperature down to reduce Nox or something. I'm going to test it within the next couple months. Try to set it up so I can do a Aba test.

The only trouble reading about this stuff is a lot of information on the Internet can be misleading from all the opinions and hear say. Only good way to figure it out is to test it and get personal experience or find more factual content. I'll have to get an afr and egt gauge to really prove any of the "known" egr facts.

I believe it's Julian Edgar over at InsightCentral who is running a custom ECU in his Insight. He's a very experienced tuner, and makes claims that he has seen healthy improvements in economy by running a lot more EGR.

EGR does end up decreasing the dynamic compression ratio, which is indeed different from the static compression ratio usually advertised. When it comes to keeping the engine cleaner after an EGR delete, it's been more of an issue with Diesels and some of the earlier direct-injection gassers because they tend to have a higher particulate matter emission, plus the fuel injected at the intake manifold in a conventional gasser tends to dillute oily vapors aspirated from the crankcase through the PCV, preventing the carbon buildups to accumulate at the intake manifold.

The op was askimg about torque. You can increase torque by decreasing pumping loses. Free flowing intake and exhaust. Back to basics. I think max fuel economy is at the same place as max torque.