Modifying a NA car

[Merrill]

Does changing a chip of a car, boost performance of a NA engine? or does it require a turbo to work? For example how do you improve performance of an Audi Q7 just by changing the engine management?

[2ndclasscitizen]

No, you can do it with N/A engines as well as FI ones. A chip/ECU reprogram/piggyback computer merely changes the engine management and fuel/air and timing settings to increase power.

[charged]

The "chip" you talk about changes the timing and fuel maps normally for better performance usually in conjunction with better intake and exhaust system to get the full benefit.

HTH

[Bob]

Chips can change many things, depending on how much the engine is computer controlled. Some that come to mind...
-Air/Fuel ratio, optimal for economy is 14.7:1, but for performance its 13:1, iirc
-Spark timing, more advance can be programmed in when owner uses better grade fuel
-Power enrichment mode, a mode that engages past a certain throttle threshold to increase performance.

[Clivey]

Originally Posted by Merrill

Does changing a chip of a car, boost performance of a NA engine? or does it require a turbo to work? For example how do you improve performance of an Audi Q7 just by changing the engine management?

http://www.superchips.co.uk/benefits.php

Superchips reckon they can increase the power of a NA petrol engine by upto 10%. The reasons this works have been, and my guess is that they will continue to be, explained elsewhere in this thread. Hope that helps.

[Bob]

Superchips are crap. As are most chip companies. A guy who has the same car as me once got one and compared it... they charged $200 to change one spark value by a very tiny amount. For chip tuning to be effective it must be custom to your car, by the company (this means multiple chips burned and tested) or you have to do it yourself by trial and error (10, 20, 30 tries to get it just right.)

[Quiggs]

Originally Posted by Bob

Superchips are crap. As are most chip companies. A guy who has the same car as me once got one and compared it... they charged $200 to change one spark value by a very tiny amount. For chip tuning to be effective it must be custom to your car, by the company (this means multiple chips burned and tested) or you have to do it yourself by trial and error (10, 20, 30 tries to get it just right.)

It depends, really. If you're comparing stock to chipped, there may be considerable reliable gains. But once you get into dialing in a car that has other performance parts- mainly cams, headwork, and exhaust- you will want to get a custom tune.

[clutch-monkey]

i have been told by a workshop that remapping the stock chip on the GT3 will net 40hp (i don't know if that's claimed, at the flywhee or whatever). i thought this seemed a bit much, but i guess it shows there are improvements

[charged]

Originally Posted by Bob

Chips can change many things, depending on how much the engine is computer controlled. Some that come to mind...
-Air/Fuel ratio, optimal for economy is 14.7:1, but for performance its 13:1, iirc
-Spark timing, more advance can be programmed in when owner uses better grade fuel
-Power enrichment mode, a mode that engages past a certain throttle threshold to increase performance.

14.7 is "perfect" in terms of a ratio - it only means it is "perfect" in terms of stoichiometry - ie: each molecule is balance on each side of the combustion equation. it also aids the cat to work best, but is not going to necessarily be "best" in terms of what the engine needs/wants.

Each engine can be very different and different A/f ratios apply. For economy 14.7 is quite rich, on load load cruise you may get away with a/f of 13. If its under high load eg power run the a/f of around 14 is needed.

The higher the a/f the more timing has to be taken out of the tune. So HP doesnt change that much Also the leaner mix produces more hydrocarbons and may not meet emmissions tests.

The best way for N/A or FI engines is actually getting a good tuner and spending some time on the dyno to get the right safe tune.

We tried various A/F ratios when my tuner dynoed my engine and found 14.4 was the best compromise under heavy wot load, light load was about 14.2, the combustion camber was very efficient so the a/f were set at that so detonation didnt take place. We actually burnt and exhaust valve because the plug was too hot, went 2 ranges cooler.If this happened on the track it would have been catastrophic. A good dyno session is worth its weight in gold and engine parts.

[hightower99]

Originally Posted by charged

14.7 is "perfect" in terms of a ratio - it only means it is "perfect" in terms of stoichiometry - ie: each molecule is balance on each side of the combustion equation. it also aids the cat to work best, but is not going to necessarily be "best" in terms of what the engine needs/wants.

Pretty much except the majority of engines out there today also want to run as close to 14.7:1 as possible as this leads to least emissions.

Originally Posted by charged

Each engine can be very different and different A/f ratios apply. For economy 14.7 is quite rich, on load load cruise you may get away with a/f of 13. If its under high load eg power run the a/f of around 14 is needed.

You seem to be backwards here... 13:1 is more rich than 14.7:1 (ie more fuel per unit air) 14.7:1 is stoiciometric but you can run engines leaner than that to gain some fuel milage (at the expense of power and increased NOx emissions) Several engines can jump as high as 18:1 for short periods of time but unless they are using direct injection and heterogenous mixture then it is difficult to ignite the lean mixture.

Originally Posted by charged

The higher the a/f the more timing has to be taken out of the tune. So HP doesnt change that much Also the leaner mix produces more hydrocarbons and may not meet emmissions tests.

First with a leaner mixture you need to advance ignition to increase your chances at igniting the mixture and you can only do this to a certain extent... power is lost when running lean. Also when running lean you produce alot less unburnt HC then when running rich, however you produce alot more NOx because of increased temperatures and the relative abundance of Nitrogen in comparison to unburnt HC.

Originally Posted by charged

We tried various A/F ratios when my tuner dynoed my engine and found 14.4 was the best compromise under heavy wot load, light load was about 14.2, the combustion camber was very efficient so the a/f were set at that so detonation didnt take place. We actually burnt and exhaust valve because the plug was too hot, went 2 ranges cooler.If this happened on the track it would have been catastrophic. A good dyno session is worth its weight in gold and engine parts.

It seems odd to me that under heavy load your engine runs better with a leaner mixture than when running at light load also because both 14.4:1 and 14.2:1 are richer than 14.7:1 they help stop detonation (the excess fuel absorbs heat). I don't quite know how a hot plug would burn an exhaust valve unless you mean that the hot plug caused some precombustion and or detonation which lead to heightened exhuast temperatures?

[charged]

Dead right mate was suffering from brain fade, youngest daughter was up most the night, then a trip to the hospital in the morning took its toll on the brain cells . You are right the higher the A/F the leaner the mix.

When we dynoed my engine Toyota 4age B/T20 valve, we ran it with just the intake trumpets with the 48mm ITB's which theoretically flow over 1100cfm. The injectors were nearly at 100% duty cycle and plus with the wrong plugs we burnt 2 exhaust valves and destroyed the spark plug on no 2 cylinder, we went 1 ranges colder 5 to a 6 on the plugs and fattened the a/f ratio-and it seems to have fixed the problem, I also thought he retarded the timing?.Plus when we run it at the track it runs a airbox which will richen the a/f ratio to about 13.8-14.0 dont really know yet because we have to fabricate a airbox or hit the track, hopefully next week end.

The failure was my fault because I got advice off someone who recommened 5 instead of 6 heat range for the plugs for the engine but he actually runs airfilter socks which restricts airflow even more and a stock ecu. We run autronic ems and the tuner started with 14.7 a/f which he thought would be safe to start with.
A lessson learned how a few changes can make a big difference...

[jediali]

Originally Posted by hightower99

however you produce alot more NOx because of increased temperatures and the relative abundance of Nitrogen in comparison to unburnt HC.

I thought nitrogen only combusts at higher temperatures, like in late high CR diesels, hence bluetech

[culver]

Nitrogen doesn't actually "combust", it disassociates. The high combustion chamber temperatures cause the N2 molecules to break down into free N molecules. These molecules then combine with free O molecules when the temperature drops. Running at stoichiometric both keeps chamber temperatures down and leaves fewer free O atoms around to combine with the free nitrogen atoms.

As for the original question, I recall Car and Driver doing an article on this. Generally the NA cars got very little boost from the chips. The increases ranged from nothing to enough that you would notice it in lap times at a track. I don't think any did better than 5%. Mind you these were on otherwise stock cars and no special/custom tuning was done for the individual car.

Turbos of course are different because you have the option (among other changes) of running up more boost.

[jediali]

so nitrogen (N) to nitrogen oxides (NOx) is dissacociation

[hightower99]

Originally Posted by jediali

so nitrogen (N) to nitrogen oxides (NOx) is dissacociation

No N2 to N is disassociation... N to NOx is oxidation... Combustion is normally used when creating the final product is an exothermic process. However when you look at splitting N2 and O2 and then recombining them to NO2 and NO3 the whole process is overall endothermic.