And the overall VE is improved on the 0.48 by the wastegate opening further and wider for the same inlet pressure due to the bigger compressors lower speed requirement to make the same airflow...

Also dont forget that 1 AR is not always the same as another AR

 

yes or by replacing cams porting head etc but the compressor still flows more air fact! even if its still restricted in the exhaust but the discussion was does a t34 need more fuel over a t3 yes

 

beat me stu

 

i think ive learnt lots from this post gonna re read it again tommorow to see if ive taken it in lol

 

this is what i'm seeing on the screen when you's start getting so technical

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welcome to my world

 

keep this crap to ya self its no good to mee

 

stu - are the days of 'mapping' numbered?

if the ideal advance / afr etc are govened by the laws of physics can electronics not simply say ' oh well the air fuel meter reads 14.1 and i've been told these old cossie engines melt pistons now (it might even be clever enough to recognise the engine spec by the noises!) so i better open the injectors more' or 'fook me that old det sensors making a racket - take off some advance' , and so on.

you just throw greys in from the start and if its too rich at idle it drops the fuel pressure a bit and so on. it runs them electronic boost controllers so you can bin the other stuff and its even got blue tooth and number plate ocr. i, so if you're in the pub and some c**t disputes that you have 500hp, when it recognises their plate it will throw caution to the wind and let you have 500 for a short time to show him.

seriously though - has no one brought out a clever box with a learning facilty that ya just plug in and stick ya right foot hard down from day one?

 

errrrrrrrrr NO

 

pgt, you can get ecus to "auto tune" fuel (to a degree) but i think detecting det is the hard part!

 

That technology has been in existence for over 10 years Paul


Its getting there.. Autronic can map its own fuelling now, just active spark to go, and the OEM's have had it years pal.

However..
None of these systems utilise the fuel side under hard load, simply because if the Lambda sensor goes down and lies, Boom.. engine has to go with it.

 

stu - since i paid to be able to read your superb techie essays and now this one about the back pressure in the turbo having impact on power and fuelling etc is now public knowledge, will i get a refund tomoz when i pick him up?

 

If you wish, yes.

 

no thats a taster to get people to pay

 

fookin ell gus when stu gave u 'mod' status did he give u a set of instructions and a manual on 'how to become clever in one easy read" ???

 

no i only act thick that way u get less challenging questions

 

i like it m8 !!!

 

 

good old KE and it's calibrated metering flap

 

But in this discussion we aren't changing anything but the turbo..

Agreed, a larger compressor has the ability to flow more air volume at the same pressure, BUT it is only able to flow more air (and hence need extra fuel and make more HP) through the engine if the overall VE of the engine as a whole (notably exhaust restriction) is improved. Stu has explained clearly how this happens with the T34 situation above.
It's absolutely not a function solely of the increased compressor size..

 

if the turbo is THE cause of exhaust restriction (or any restriction) why bother modding the exhaust ports when you tune the thing (black art?)

 

so on-going from that .... is it not better to have a t34/t35 as there is a benifit to the overal engine package (not just power) in reduced heat and better airflow through the engine which should then have better efficiency ????

 

Presumably that off topic and pointless comment was the result of too much beer Rick?


A bigger turbo is almost always better for the engine until you start to produce stressfull levels of power with it. Unfortunately, this also means less useable power low down, which is also better for the engine.... lol

 

why is that Stu. less useable power low down is better for the engine.

cheers

 

Less power = less stress.

It was a tongue in cheek comment mate.. sorry

 

of course you could make an ECU thats completely self-mapping. as far as i understand it, mapping is not based on "a hunch" it's based on facts. ie if AFR = xxx then injector duration much = xxx

i wouldnt have thought mapped back off fueling etc. when the gauge reads lean just becasue they've "got a hunch" i'm sure if stu sat down long enought and wrote down EVERYTHHING he knew about mapping you coudl get a software designer to make a program that completely automated the process...

thats the whole point of computers... lol

it's probably DECADES away, but the technology's there, it's just take enough clever bods to put something together

ps if im wrong and you do map "on a hunch" then i take all that back as its currently impossible to program that intoa compuer without some form of advanced artificial inteligence

 

jesus christ i cant spell for shit today!

 

Did you miss the part where i said:


By any chance Jim?

 

 

so .. the overal question is ... what would the best turbo be in the t3/34/35 type range .. obviously the bigger the exhaust housing the more lag but then you get reduced temps etc ... so how about a monster sized inlet compressor wheel in relation to a smaller exhaust wheel i guess this would restrict the exhaust gasses but would help the turbo to compress more air quicker.... or have i got it wrong as such ...

one of the best threads i have seen for a while tho.. thanks to all who have added comments...

 

That would create monster surge.. now your straying into specifying turbochargers you see...

small turbine spin fast and easy but mated to a large compressor will try to force air into an engine that cannot accept it and thus compressor surge and ultimately stall is the result.....

 

Gus you robbing bastard - the balloon analogy was the one I used when explaining to Stu where I was coming from when we were originally discussing this - hence why it is mentioned in his explanation .

 

I wondered if you would spot that particular example of thievery Mike

 

mike i hadent read that before in any detail as its too long a q for rich m what if the ve of the engine is ok but the compressor is the factor letting the side down uprate the compressor and leave the exhaust housing the same it still needs more fuel

 

right .. so im learning all the time on here....

excessive compressed air is a bad thing..
lack of or excessive fuel is a bad thing..
too small an exhaust wheel creates a restriction..
excessive rpm on the shaft is a bad thing..
deciding on the right turbo is not easy..
when you change turbo you need a different chip..
running a smaller turbo at higher pressure boost pressure creates excessive heat..
excessive heat creates loss of power..



or should i just ....

pick up fone ... quote credit card number to correct person .. take car to said person .. come home happy but skint

 

this is a bit off topic but for the tuners what turbo would you recomend for a stage 3 2wd saph with standard rebuilt engine exhaust filter 500 cooler on greens, wanting around the 340bhp area if thats not to much. Will a t34 with .43? housing be ok cheers

 

possibly, but it would mean you've got an unusual exhaust/compressor combination for that to be the case.. and isn't the case when changing from T3 to T34 as I understand it
Stu?

 

yes but a yb can consume more air than a t3 can produce yeah the exhaust housing is good for 350bhp yeah just the t3 compressor isent yeah so we fit a .48t34 and we then have a 350bhp capable engine still utilising the std exhaust housing

 

ok gus... how about a .63 ????

 

yeah yeah.. but the .48 T34 exhaust housing isn't the same as a .48 T3 housing... as Stu kindly pointed out in an earlier post..

 

it is rich the housing is identical!