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General engine tuning tips (VERY General)

Discussion in 'General car Chat' started by obi_waynne, 3 October 2006.

  1. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    39,351
    From:
    Deal, Kent UK
    Car:
    A3 2.0 TDI
    Just thought I'd put this here as it covers most of the frequently asked questions. Obviously I've knocked this out quite quickly (10 mins to be precise) so if i've missed anything out or made any glaring errors let me know. :wink:

    Smaller engines under 1.4l
    These are relatively solid and can withstand a fairly good redline usually higher than some of the larger capacity engines. As these engines do not produce much power there is not much of a gain to be had from them. Adding an induction kit and exhaust will make the car harder to live with. A fast road cam that exploits the high revving nature of these engines is probably the best thing you can do. It is also worth increasing the fuel by getting larger injectors. (Often models in the same range with larger engines have compatible injectors so see if the injectors from the 1600cc will fit your 1300cc engine.)

    Mid size engines
    1.4-1.8l This is actually a very wide band of engine types and sizes. The base upon which to build is greater so there is more of a reward from tuning them. I would recommend a sports exhaust particularly on the higher revving Japanese engines. I would still hesitate to add an induction kit but a panel filter which is a direct replacement for the standard paper air filter is a good compromise. Towards the upper engine sizes of this range you will start to see gains from the addition of forced air induction either a turbo or supercharger. Because you are adding pressure with forced air induction you should seek to reduce the compression ratio of the engine and run at a relatively low boost level. Addition of Nitrous Oxide injection can also yield some silly power gains. Fast road cams will have a good effect too but not in isolation - to free up the power generated by the cam you will need the sports exhaust and a better flowing air filter.


    Larger Engines
    2.0 upwards including V6 V8 etc.
    These are the big daddies. The tend to provide much more low down torque than the smaller engines and all have good tuning potential. Inductions kits generally work quite well providing they have a good feed of cold air, as do sports exhausts of 2.5-3inches in bore diameter with a sports catalyst. The larger the engine the more you have to gain by adding a sport computer or reprogrammed ecu. Due to the nature of these big engines I would not recommend a turbo application due to the internal engine modifications that would need to be applied, but mild supercharging is still beneficial. CAMS would also have a good impact on the performance of these engines, especially the silky smooth V blocks, but as the gains are much bigger than with the smaller engines fuel uprating becomes vital or you run the problems of running too lean. Temperature control is vital as the larger cylinders produce and hold a lot of heat. Ensure your cooling system is up to spec and use water wetter to raise the boiling point of the coolant. Overheating can be a major cause of engine failure.


    Diesel Engines
    Diesel engines run differently to petrol engines in that the compression within the cylinder causes the fuel and air to burn as the pressure increases. The big problem with diesel engines is that they have very high compression ratio's and the fuel does not burn as quickly as petrol engines so typically the engines have much lower redlines. This is why many performance diesels come with a 6 speed gearbox with low ratios to cope with the relatively short power band. Manufacturers have experimented with pre warming the diesel before it goes into the engine and various methods of direct injection so it is actually quite hard to give general tuning advice. With nearly all Turbo Diesel engines there are quite silly power gains to be had with a remapped ECU - or the addition of a piggy back ecu which takes over much of the timing calculations. 'Chipped' diesels are still very economical and users have reported that they are much more free revving and easier to live with. Servicing is vital though to keep the engine running at peak efficiency as a chipped engine is quite unforgiving.


    Turbo Engines
    The largest power gains to be had are on vehicles equipped with a turbo. A straight remap of the ECU yields a lot of extra power sometimes as much as another 25-30%. Turbo engines have to cope with a lot of stress so most leave the factory in a very strong state. Uprating the turbo with either a larger turbo or twin turbo set up can help improve power even further but with this route all other aspects of tuning should be explored to release the full power available (Sports exhaust including flowed down pipe, induction kit with a cold air feed, larger valves and flowed head, bigger injectors and a larger more powerful fuel pump, strengthened bottom end of the engine if you are increasing the power by more than 50% of its standard spec).
     
    Last edited: 16 February 2010
  2. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    From a diesel perspective, anything that isn't turbocharged is a waste of time from a tuning POV. Similarly, anything that isn't using electronically managed direct injection is a pointless tuning proposal.

    Get rid of those two ointment bound flies and things get more interesting. My 2001 plated Peugeot 406 2.2HDi has been re-mapped from factory spec 136bhp (and it's pretty good in that tune with 235lbft to play with!) to a whopping 192bhp@4150rpm and 329lbft (yes, that's right, I have NOT confused Nm with lbft) delivered from 2250rpm. This endows the car with mid-range thump that wouldn't disgrace a Boxster or Audi TT with the silly enigne option. NO stopwatch necessary, this is a genuinely rapid car now.

    All you anti-diesel folks will bang on about 0-60. Yep, well, I've never put a stopwatch on it in anger but you can do it in well under 8 seconds without going over 3500rpm! In gear is a bit of a giggle too - 50 to 70 in FOURTH in about 2.5 seconds!! 70 to 90 in fifth in under 6!!! Flat out, who cares, the factory spec is said to be good for 129mph.

    Go figure for yourselves - and then dial in over 35mpg when driven in anger - at the age of 36 I've half grown up but, boy (or lady) do I lurrve that sheer muscle.

    What you MUST do, however is;-

    1. declare it to your insurers - although it's probably undetectable, any underwriter will do ANYTHING to avoid paying a claim

    2. Keep your servicing right on the nail. By the book or more often with the oil/filter swaps. A re-map is really only using up the reserves the manfacturers built in to cope with neglect. Sometimes I wonder if it's done to make it possible to sell petrol models, though. I recently drove a BMW 328i petrol and it felt so bloody spineless in comparison.


    3. Set aside a couple of hundred quid a year extra for tyres - you're gonna enjoy the drive :))

    Kind Rgds,

    Paul.
     
    Steevo likes this.
  3. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    39,351
    From:
    Deal, Kent UK
    Car:
    A3 2.0 TDI
    Nice post Paul you make some good points - I'm thinking of doing a whole diesel tuning section on the site and am looking into internal engine mods etc that work well on Diesels - I'd appreciate your thoughts. A remap is sooo easy and rewarding but there must be other options as well. I'm thinking turbo upgrades and modifications, head work, Cams etc. The engines are similar but there are some major differences so it would be interesting to see how these compare.

    You seen the spec on the BMW 330D? Just proves they can make a VERY quick diesel from the factory.
     
  4. the_names_james

    the_names_james Torque Junkie

    Messages:
    134
    From:
    Surrey, UK
    Low weight and high power are the most essential things for a fast car.

    Keep the inlet air as cool as you can.
     
  5. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    39,351
    From:
    Deal, Kent UK
    Car:
    A3 2.0 TDI
    I think I got too focussed on the Engine - thanks for the tip James.
     
  6. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    Yes, I've driven a current 330d and also a 535d. Both are disgustingly rapid from the factory. These engines can still be made to deliver more torque, but you have to question if it's really necessary given the ease with which they both fling themselves foward in response to a gentle squeezing of the right toes :)

    I do think that manufacturers modestly undertune the current crop of performance diesels in order to create a place in the market for their petrol powered models. For some folks, only petrol will do. Curiously, in my estimation these are of the older generation who will not even test drive a diesel car because 'they're slow and nosiy, aren't they?'. Just look how many current model Micras are being driven around with Nissan's excellent but spineless small cpacity 4 cylinder petrol units. Try the dCi 82, for example. It handles like a go-kart (Nissan is bloody good at track-like steering in road cars) and accelerates absolutely beautifully. It would suit my Dad perfectly.

    As for internal mods for sophisticated diesel engines, I think that the rewards obey the law of diminishing returns. With forced induction there's only so far you can go with cam/valve lift and air (gas) flow. Especially with a diesel engine, given the limited rev range there's not that much reward from tuning a head in the traditional way. Diesel burns very slowly (hence the 4000rpm peak BHP most achieve, even if they will spin to over 5000rpm).

    Getting the flame front inside the combustion chamber to accelerate faster than the piston crown is the only real option, and this is to some degree achieved by allow small amount of fuel to be injected during the expansion phase of the engine's cycle. Too much of this and you get smoke and soot, and burn a load of fuel. Increasing the BMEP (brake mean effective pressure) by means such as increased boost can assist. This, too, is a double edged sword as the biggest fraction of the atmosphere is nitrogen, which, although good for cooling, is still incombustible. That's where nitrous comes in, in the same way it does in a petrol powered vehicle. The gains achieved in this way can be absolutely silly, but given the cost and legal position with regard to road usage it's a bit of a white elephant.

    Increasing the cetane rating of diesel fuel is quite effective in increasing the release of 'free' power. With a diesel engine, the key is getting the fuel to burn more rapidly, as opposed to a petrol engine where octane number is God. Higher octane petrol fuels burn more slowly and resist pre-ignition better than low octane fuels.

    Good results can be obtained with cetane improvers. Sadly, these can prove expensive and should not be used in engines that are Euro Iv (2004) compliant. Strangely, the 2.2HDi I use (which is a 2001 model) is 2004 compliant. The particle filter (subject in itself) can become blocked or excessively obstructed by use of such products.

    I will post more very soon on this topic, but I'm being hounded by my kids to cart 'em up the road and fetch 'em back a decent Indian takeaway - they've got style too ;)

    Cheers to all,
    Regards,

    Paul Anderson.
     
  7. obi_waynne

    obi_waynne Administrator Staff Member Moderator

    Messages:
    39,351
    From:
    Deal, Kent UK
    Car:
    A3 2.0 TDI
    Cheers - Paul - great stuff. You've swallowed a technical manual. My wife is writing an article on Octane for me and I'll ask her about cetance - she has a sience degree so she knows her stuff and might be able to give some interesting suggestions at the chemical level for us. Hope the kids like the curry and appreciate the heavy sacrifice you are making to put food on their table :wink:
     
  8. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    They're like a couple of bloody pirhanas - eat ANYTHING. No sacrifice really - I, too' like my tucker.

    The weight thing is very very sensible. Not only does less weight mean better performance for free, it also puts less load on tyres, which allows braking and handling to be optimised. It also reduces the load on the environment as less fuel is required, thereby the release of exhaust gases is reduced. I'm not a green lobbyist, but I do take some care to minimise environmental impact. (strangely, this also applies to my eating habits - let's dump the supermarkets with their over priced low quality products. Let's dump the crap petrol and diesel,too. For the record, I buy meat from two or three local farmers and utilise my big BIG freezer, which means I can live on top quality stuff every day for well under supermarket money. This helps fund my fuel bill and heavy right boot ;)

    Back to performance diesels, and I've said it before elsewhere in these discussions, but engine mass/weight is a standard problem with diesel cars (especially FWD ones). That heavy engine can upset the handling balance of a car. Diesel units are heavy; they're dealing with big compression ratios and big torque figures. as such, the bearings are larger in diameter, the gearboxes belong in lorries and tractors even if the change quality is good. Clutches are getting on for 12" diameter and require fluid operation and servo assistance to make the things pleasant to drive.

    As for the environment, any pollution is bad, but, come on Mr Blair, we do rely upon our cars for essential travel. Let's face it - is going to work a luxury? I wouldn't go if I didn't have to! So how bad are we that look after our cars and optimise their performance? Commuting is not a hobby. And if, let's sat I go for a fifty mile blast on a Sunday once in a while. I'm still contributing to the HM C&E pot for the privilege of buring fossil fuels.

    Consider the pleasure yatching fraternity. They're pissed that they are gonna be required to pay duty on fuel. If they don't pay duty on their leisure activities, why should you and I? Please, Mr. Brown, can I claim back duty on diesel that I burn for leisure in my car?

    Think it through,

    Rgds,

    Paul.
     
  9. JammasterJ

    JammasterJ Wrench Kid

    Messages:
    12
    my dad drives a 330 and i can agree, it's quite the beast! driving that then going back to my Corsa is quite depressing lol!
     
  10. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    Oh yeah - modern diesels go stupidly quickly.
     
  11. astracoupe

    astracoupe Wrench Kid

    Messages:
    10
    if you think yours is fast you want to drive a remaped vauxhall astra sporthatch 1.9 cdti blow your pug away and its only a 1900cc
     
  12. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    I expect it would. I think the 1.9 litre unit is the Fiat / Alfa JTD which, I think, offers 150bhp in stock tune.

    A good remap has got to shove this to well over 200bhp, which is going to move an Astra very very nicely indeed.

    I recently drove a re-mapped Mondeo 2.2 TDCi - that was pretty impressive too.

    My ageing 2.2 does have its limitations - the worst of which is there's so much bloody turbo lag below 2000rpm and then grip problems which manifest as torque-steer when it's really pulling.

    In it's defence, it's a very smooth unit with twin balancer shafts and it's also barely audible inside the car.

    Have fun and stay safe.

    Kind regards,

    Paul.
     
  13. Pixel

    Pixel Road Burner

    Messages:
    464
    From:
    Swansea, Wales
    Car:
    Ford Fiesta Zetec-S
    Never buy a straight diesel :p
     
  14. Joe

    Joe Grease Monkey

    Messages:
    5
    From:
    Clonmel
    Car:
    Punto 1.3Multijet
    Anyone ever hear about remapping a 1.3 diesel punto??
     
  15. putno driver

    putno driver Wrench Kid

    Messages:
    16
    On the subject of Puntos, mine's a petrol one and needs a lot of pushing to get moving.I have seen items advertised on the net called "vortex generators" sort of mini turbo fans and chip tuning stuff.Are these basically bolt on tuning mods that actually work? Comments opinions appreciated .
     
  16. pgarner

    pgarner TC ModFather Moderator

    Messages:
    16,523
    From:
    Lockerbie, SW Scotland
    Car:
    Octy smoke machine
    vortex generators, electric supercharges ecoteck valves are all a waste of money

    the vortex generators do what just about every intake manifold does anyway which is cause a disturbance to the airflow to allow better circulation

    the electric superchargers - theres no way the motors could substantially move enough air to make much a difference

    ecotek valve if you like induction noise then there alright you get the same sound when you lift off but no difference to performance

    the chips on the other hand.

    the cheap tuning boxes etc that are on ebay for a tenner dont bother there mainly just resistors that trick your engine into thinking the chokes still on. risk damage damage to engine

    reputable companies will offer proper chipping or remaps to the ECU which will give a performance increase without damage to the engine. granted on a NASP engine your only looking at about 5 - 8 bhp
     
  17. putno driver

    putno driver Wrench Kid

    Messages:
    16
    I got the impression a remap is only going to be of any benefit if the motor has a turbo fitted.
    Vortex generators are claimed to give between 7 to 12.5% increase in power. On my car that may make a difference. I think they cost about 30 quid and even a girle can fit one.
    Do you know of any that have been independently tested?
     
  18. pgarner

    pgarner TC ModFather Moderator

    Messages:
    16,523
    From:
    Lockerbie, SW Scotland
    Car:
    Octy smoke machine
    an easy way to look at it

    if they claim they can get 7 to 12% lets go middle ground and say 10% ( its easy to work with ) your punto would be looking at around 8 bhp with my bora 18bhp for £30 .now a £230 k&n kit claims that it will give me around 10bhp and they have dyno graphs to back up a £600 full exhaust system wil give me around 10 as well. if it works why doesnt car manufactures add them as standard.

    the likes of intake filter exhausts and the engine map are constrained by the manufactures simply because people dont look after their cars, also noise regs and emissions

    fitment will be easy itll just be a case of removing intake pipe inserting and a couple of jubilee clips
     
  19. bicko

    bicko Wrench Pro

    Messages:
    40
    From:
    merseyside
    Car:
    fiesta 1.3 wrc
    for the price of getting youre 1.3 diesel chipped, why not buy a punto GTT rear end write off and swap the engine, loom running gear ect...
     
  20. jarrus

    jarrus Pro Tuner

    Messages:
    3,502
    From:
    West Midlands, UK
    Car:
    Suzuki Swift Sport
    good power gains can be had from a mech inject diesel if done correctly...
     
  21. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    You can get nice numbers from mech IDI engines if you're prepared to spend a lot of time on them. They'll never match a DI engine for economy in similar tune and probably won't deliver the silly torque figures so beloved of us derv heads.

    IDI's are much simpler and cheaper to maintain and service - there's a lot to be said for a 'traditional' diesel turbo engine. Even the old XUD 1769cc turbo motor was pleasant in a 405 estate. 90bhp moved it around without embarassment. I don't think it's enough to shift a 406 though, they're much heavier cars.

    I ask you: Where's the progress?
     
  22. jarrus

    jarrus Pro Tuner

    Messages:
    3,502
    From:
    West Midlands, UK
    Car:
    Suzuki Swift Sport
    I like the old engines for there reliablity and simpisity, I found my car on auto trader with very low miles on it so I just had to have it...

    I bought it in january 2007 when it was 9 years old...a old man had it from new before me adn hardly use it....it had 25500 miles on the clock?!?!?
    I called up the dealer and i said it sound good but this milage sounded a bit too good to be true and he said mate you've jstu got to come and look at it....

    Yes it's not as economical but I can tune it up myself with a set of spanners and allen keys rather than a laptop...it's just easier....in the future I'd probebly get an Alfa Romeo 147 1.9 JTD Mutijet i think i love those cars unless i can find a low milage on a 306 hdi and a 2.2 hdi engine...i guess becasue mines one iof the laster models wit the older engine I reckon I could do it without having to buy another car...jsut put the 2.2 in my car it has the digital miles guage..
     
    Last edited: 2 June 2008
  23. HDi fun

    HDi fun TC ModFather

    Messages:
    15,384
    From:
    Buckinghamshire UK
    Car:
    Passat 2.0 TDi
    I don't think it's going to be quite that easy. The HDi engines are totally different from the XUD series. The only common ground is that they both run on diesel and both are four cylinder units.

    You'd certainly need the HDi ECU and wiring loom just to get the thing started.
     
  24. slacky

    slacky Wrench Kid

    Messages:
    10
    probably not benefitial to anyof you lot, but under your bonet there is a rubber seal at the top of the bonet take the rubber seal off, this will allow the hot air to escape from the engine giving you an extra 3 bhp works on any car ;)
     
  25. speed culture

    speed culture Tuner

    Messages:
    53
    From:
    Seychelles
    Car:
    T. Corona 3sge Gen3
    uhm, dad has a 1.6L Golf with one of these things and frankly.... i don't see much different appart from the bottom revs.... top.... basically the same thing....
    don't know might feel different on other cars
     
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