Its not, at all, more airflow lower down is the potential for extra torque, Phil is (unsurprisingly) completely wrong.

Fucking hell Chip...you really take shit too seriously..what i say about compromise is very true..the F1 engine is uncompromised..its a level playing field..the technology in thats is unreal..being able to remotely lean the engine adjust timing is just so cool..nothing comprimised..it does what it says on a tin..to go fuck off quick..its more to do with driver/tyre combo!

For JJ i can only say that you get more airflow than std which would mean more fuel needed to get a good mix but then thats not good at low RPM..i really dont know nor do many folk..i aint ashamed about that..its only me that has made this thread be thankful i dont let Chips pedantic wankerish ways get me down ;)

So lets go back to my penultimate post (excluding this one ;) ). Are the statements that I have made correct? (best to make sure it is going in PMSL)

Second, are there any negative effects of the increased port size. For the purpose of this article, lets use Karl Norris' range of heads (becuase IIRC he has std, stage 1, stage 2 and 3 (?).

So given that this is for scientific interest. Lets say I simply bolt a stage 3 head onto my car with the std cams and the same turbo (ie keeping with all other things remaining equal (which is what ceteris paribus means for those that didnt know ;) ))

Now clearly the stage 3 is designed for folk looking to do other mods also, but lets use the example for the purpose of the discussion. We know that the engine will flow more air, and as such the map will need to be modified to reflect the increase requirement for fuel.

But what else is going on?

JJ

LOL..this thread is such a farce to get a Chip technical discussion goin to put him favourable for a technicion on PF..it wont ever happen..stick to PM or put this in the TECHNICAL room. :roll:


Jeezs i help a folks thread for anothor persons cause :wall:

With the greatest of respect, Phil - what the fuck are you talking about?

You started out trying to assist on this subject, but the last couple of posts have simply been Chip-bashing!

This thread started as a good open discussion with the likes of Chip, Gareth T and when you were interested, yourself!

Now you have got bored, the thread is now being diluted by an irritating diatribe!

Please please please stay on topic, or move on :wall: :wall:

JJ

As I explained to you many times in this thread, JJ doesnt want some over simplified crap from you, he wants details that he can learn from.

JJ, can you just confirm that if i'm correct, as either me or Phil seems to have got the wrong idea from this thread at the moment :top:

Phil, why is not good to get more air and fuel in at low rpm?
More air and fuel is more TORQUE, do you not like engines with torque?
Im not being pedantic or wankerish, im being ACCURATE.

More airflow into (and remaining in the engine till combustion) at low rpm is a good thing, why on earth would you possibly think that less is better? :cry:

:roll:

FARCE

This thread would have died without my input..you know it God knows it :roll:

..all i get is a barrage of abuse cause i am apprently thick...but you need me how ironic? :roll:

I wont help input anymore for you as you take it as causing shit where infact it gets you replies if your chimp just could moderate his self beleif he is the choosen one :wall:

You are correct. I am trying to understand the constraints and considerations that are required when tuning a turbo charged engine. I am hoping to learn the principals, not the specifics, so that when somebody discusses tuning modifications that I understand why, not just how much ;)

Stavros made an excellent point very near the beginning - many people refer to BD10 etc etc without even considering what they do to lift or duration.

I am trying to understand how people come up with the ideas, not just which bits!

JJ

OMFG here we go :violin:

this is a good thread JJ, keep it going!!!!

...with a little help thats not appreciated :wall:

Phil for gods sake just fuck off, no one wants you in this bloody thread, even the topic starter.

Go away and talk about shagging MikeR or something, you havent got a fucking clue what you are on about with engines and constantly pretending you do is just making you look even more pathetic than normal.


:loser:

repeat to get back on topic please gentlemen

So lets go back to my penultimate post (excluding this one ). Are the statements that I have made correct? (best to make sure it is going in PMSL)

Second, are there any negative effects of the increased port size. For the purpose of this article, lets use Karl Norris' range of heads (becuase IIRC he has std, stage 1, stage 2 and 3 (?).

So given that this is for scientific interest. Lets say I simply bolt a stage 3 head onto my car with the std cams and the same turbo (ie keeping with all other things remaining equal (which is what ceteris paribus means for those that didnt know ))

Now clearly the stage 3 is designed for folk looking to do other mods also, but lets use the example for the purpose of the discussion. We know that the engine will flow more air, and as such the map will need to be modified to reflect the increase requirement for fuel.

But what else is going on?

JJ

if you increase port size, you must lose air speed, what would be the effect of this?
this would be more of an issue low down with lower boost i would imagen?

If you go too large on port sizes, then (particuarly when not on boost) when the engine is at low rpm, the gas speeds travelling down the ports will be lower, which leads to less flow towards the end of the intake stroke, when you are relying on te gas coming in having momentum (as the vacuum in the cylinder is no longer as great) and also when the piston starts to come back up if you have high enough gas speeds heading towards it then it stops reversion of the gasses.

Most good aftermarket heads will therefore NOT go for massive ports, but will instead concentrate on the shape of the ports, and particuarly the valve throat, where gains can be made in flow (by removing restrictions) without having to increase diameter and lead to a drop in gas speed.

that makes sense :top: :top: :top: :top: :top:

what about exhaust side?

So what we need is variable ports! Ones that are nice and small when you are off boost, but expand nicely when on boost!

Hmmmmm - maybe not! :cry:

So given that my truly innovative cylinder head above is unlikely to be the correct solution, is it possible to compensate for the reduced flow any other way?

JJ

You want variable port sizes, variable compression ratio, and mapped valve timing under solenoid control, so that you can alter the timing and duration of opening and even the acceleration rate to be optimum, this is the direction things are heading.

By altering the cam timing alone you can see quote good gains in terms of recovering lost bottom end, in fact this is what your M5 does to tame its relatively racey cams :top:

To be fair, the M5 cheats - what with its VANOS system. But this at least shows how the M5 can have its cake so as to speak and eat it!

Cool - we have established that it is more important to improve the shape of the port over the overall size.

Lets go back to the compression ratio. Can we further discuss exactly how the compression ratio affects the whole engine efficiency, and what makes them initially not so good without proper setup

JJ

JJ

jj buy this mate

http://www.amazon.co.uk/Forced-Induc...5549888&sr=8-4

ive been in work all afternoon so sorry i couldnt add my points in :oops:

Hi Gareth - believe it or not, I asked my wife to get this for me for Christmas! I even gave her a link to amazon!!!

do you know what she said? She couldnt find it in fucking halfords :wall: :cry:

Book now on order! But that doesnt get you out of the question though! ;)

What happens when the compression is lowered?

JJ

first we need to understand how we made power, which is simple

P x L x A x N

P= peak cylinder pressure
L = length of crank stroke
A = area of piston
N= number of power strokes

so what so you think we are increasing if we raise our dynamic compression? ( more boost, more air in about cylinder, more optium ignition and the rest)

Probably a far better idea than posting on here TBH, lol

Must confess ive never actually read a book on FI tuning, and only ever read properly one book on engine tuning, which was 15 years ago about the A series mini engine, i just tend to work things out as I go along :oops:

if nothing else changes,,, your peak pressure is lower,, and you loose power ;)

JJ do you normally get people to talk for you?

the power loss suffered from lowering compression can be counter balanced by adjusting other areas of the engine to further levels than could be obtained without lowering compression.

I.E boost and ignition

Although if you advance the timing, you get a lot of it back, and possibly (if CR was too high to begin with) you end up with more power.

thats why i said "if nothing else changes" ;)

didnt see that mate :top:

Of course you cant ask a book a question ;)

Right, so if P X L X A X N = Power, then as stated, it logically means that if any of the above variables are reduced, then power will be reduced.

As such, we need to compensate for that loss in order to return to where we are. Interestingly, the rest of the items on this calculation appear to be difficult to modify (eg area of piston, length of stroke) and to increase the number of strokes simply means more rpm for the same given power level (?)

I think that we established that the cam timing can be altered to improve the off boost performance. Forgive my dullness, but which part of the equation is the cam timing affecting?


JJ

What are you talking about Phil? :?

JJ

Sadly that equation doesnt really have enough detail to really show up cam timing specifically, but it will basically effect the peak cylinder pressure, because it alters the VE of the engine at any given rpm.

Okay

So lets leave the cam timing and the VE out of it just for the short term.

Exactly why does the lower compression ratio allow for greater levels of advance? Sorry if I am asking old questions.

JJ

yes it does,,, if the VE drops,, the peak cylinder pressure will drop :top:

Because the peak cylinder pressure will drop when you lower the CR, so you can advance the timing again which will increase cylinder pressures.

Indeed, which is what I just said :?

that forced induction tuning book is great but it HAS some incorrect stuff in it, nothing much, but few minor points.

i cant get over phil in this thread, over confidence, dillusions, or taking the piss, im not sure, but its at least one of them as he spouting utter crap most the time and then thinking this thread would be nothing without him :?

sorry chip im watching tv at the same time :oops:

FPMSL :cry:

engineering the world rally,,,,, bloody intresting aswell :DD: :cry:

well fuck off and watch it then before you end up as useless to this thread as phil :cry: