Constructive criticism

24 December 2012 — dan

A reader writes:

From: Al
To: "dan@dansdata.com"
Date: Sun, 23 Dec 2012 14:25:11 -0700
Subject: A little knowledge

I read your Dan's Data on the subject of power chips and must say you have lots to say about a subject you know nothing about. You state that engine timing before top dead centre will cause problems and can destroy the engine. Fact is every engine operates with timing set to vary from 15 to 5 degrees before top dead centre depending on load and rpm. I don't know where you pick up your information but do some serious research before you stick it on the web. I do agree chips are a bunch of hokey.

You're quite right, Al; I've fixed the article. Thanks!

I am gratified to note that now that I have fixed the one mistake you could identify on that page, I have presumably graduated from knowing "nothing" about this subject, according to your intriguing system of evaluation, to knowing everything about it. Will you send me my Ph.D in Automotive Engineering right away, or do you require a small processing fee?

(It's also interesting that that guy from the chip company who offered me handsome remuneration in return for writing a "white paper" about their products didn't notice the mistake either.)

Posted in Cars, Shop talk. 10 Comments »

10 Responses to “Constructive criticism”

  1. RobL Says:
    24 December 2012 at 7:29 pm

    Associates don't let drunk Associates email after the office Xmas party....

    I read the same piece way way way back and put in my 2c re: pre-ignition and detonation and didn't pick up on the TDC thing either. I do apologise.

    On more interesting note is that there's sometimes power and economy gains to be had through chipping by removing "cheats" used by large evil corporations (long may they pay us) to get a car though homologation and post a pretty (unrealistic) fuel ecomony number. Get an engine calibration enginner drunk enough and they can tell tales that'd warm the soul of smokey Yunick about "optimising" a car through various legalities.

    Another thing chipping can do is remove the irritating "engine fault" light when your shiney new diesel particulate filter decides you haven't been driving in the "right" way and throws an expensive wobbly,
    again.

    Merry Christmas Dan.

  2. Max Says:
    25 December 2012 at 1:34 am

    It clearly was a forgivable mistake. After all, mechs have fusion engines, and those don't require conventional ignition...

  3. Stoneshop Says:
    26 December 2012 at 6:24 am

    The performance of a 1962 Beetle may be considered feeble, but it *CAN* climb a 45 degrees slope in first gear.

  4. hagmanti Says:
    27 December 2012 at 12:32 am

    That last link in the article doesn't work for me, in Chrome, unless I replace howtospotapsychopath.com with dansdata.com

    --Me

  5. moetop Says:
    29 December 2012 at 1:46 am

    He seemed a bit harsh. For some reason I had thought top fuel drag racers operated ATDC (Which I cannot find reference to anywhere), but A quick Wiki search does show a Nissan engine running ATDC so his statement that "every engine" operates "from 15 to 5 degrees before top dead center" is not really correct. But that is nit picking.

  6. Fez Says:
    3 January 2013 at 3:27 pm

    Just to throw in my 2 cents worth-

    The 5-15 degree TDC figure is quite conservative, my car runs a base 10 degree advance on the distributor and the electronic spark control advances the spark even further depending on engine speed, load etc.
    As an example, with the car idling at operating temperate total spark advance on my engine is 16 degrees. Briefly free revving will see advance jump above 20 degrees. And i believe that under full throttle at the top of the rev range total spark advance can reach a maximum of 32 degrees (on my engine at least).

    Big spark advance is needed because the time taken for the fuel air mixture in the cylinder to burn is relatively fixed, while the speed of the engine is variable. The ECU will time the spark earlier or later so that maximum pressure is reached at around the same crank angle regardless of engine speed (usually a little after TDC).

    Manufacturers generally run less than maximum safe spark advance for longevity and fuel efficiency. Older cars (like my mid 80's Toyota) ran slightly richer higher in the rev range for protection from pinging, but isn't done so much now. There are small gains to be had from adding a little advance or leaning out the top end, but the several hundred dollars for a chip on a standard car would be better spent elsewhere.

  7. wumpus Says:
    9 January 2013 at 4:24 am

    Note that a quick google showed a megasquirt (unprogrammed) that cost 1/10 of a MoTeC system, but isn't legal in any place that has pollution controls (possibly for not polluting enough. You could easily program it to produce less pollution than most ECUs). Getting one with programming for the right car and (hopefully) the right cables to plug it in will cost at least 3 times that amount (but less than MoTeC due to not spending the cash to be blessed by the appropriate authorities), but should be less likely to destroy your engine than flashing your own tune and running a smoke test.

    Really just leaving this here since it seemed a DIY-GPL friendly audience. Not at all recommended for "drop in and magically transform your car". Possibly recommended for going from "must be repaired by a factory authorized technician" to "must be repaired by someone with a laptop and USB cable and not afraid to use them".


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