M10 ITB´s

[Gunni]

so how big should they be?


It will eventually be turbo so if that matters take that into consideration

[Turbo-Brown]

just replied to this on E30Tech, but here's the reply copied over for all to see

How much power you gunning for?

40mm is good for about 50bhp / cylinder N/A which would be a 200bhp N/A M10.

Don't need to be any bigger with a turbo I wouldn't think.

Try to avoid getting greedy as many do and speccing too large a throttle bore as all that does is reduce low end torque and take away throttle travel effectively as you get to a point where the throttle isn't the limiting factor on power so opening it any more doesn't do anything!

[Yaninnya]

It will eventually be turbo so if that matters take that into consideration

There is no any technical reasons for fiting throttle bodies on turbo engine.
Jan

[Turbo-Brown]

Throttle response?

Better potential for air flow leading to more power for a given boost level?

Think those are two pretty decent technical reasons for fitting TBs to a turbo engine!

[Gunni]

Thanks,

itԚ´s just that ITBԚ´s on ebay donԚ´t cost ANYTHING, and since this will not be run by a MAP sensor only but
Alpha-N and MAP compensation

So something in the 36-38mm ITB should be good,
What motorcycles have that?

if 40mm = 50hp does 36mm = 45hp?
but 180hp motorcycles most have over 40mm throttle bodies,
so I should maybe be looking at a 600cc bike?

[Turbo-Brown]

Assuming that the cross sectional area has a fairly direct bearing on power, I'd say that with a 36mm bore having 80% of the X-sec area of a 40mm bore it'd give 40bhp/cyl.....although that's just a guess.

Be interested to see a correlation between bike power and TB bore.

The 50bhp/cyl with a 40mm bore came from Jenvey's website.

[karaokebykris]

iirc Suzuki GSXR600 have 38mm ITB, would be interested in more info on this as i have a spare m10 lying around....

[Gunni]

I think something of a 33-35mm would be ideally suited to a M10 then, making full use of the NA tuning , and air pressure wave tuning, although IԚ´d need to calculate the lenght of the runners as well

[Yaninnya]

Throttle response?

Just only explain why? Throttle response in turbocharged engine depends of absolutely different things than in NA (capacity of whole inlet system, dimensions - or better weight - of rotating turbo elements, length of exhaust manifold, etc).

Better potential for air flow leading to more power for a given boost level?

Yes the air flow at throttle bodies wil be better but in inlet pipes between turbo, IC and intake to throttle bodies will be exacly the same. Also the speed of air near TB will be a lot lower which is not good for inlet efficiency.

Think those are two pretty decent technical reasons for fitting TBs to a turbo engine!

As above.
Jan

[Turbo-Brown]

That all depends on the flow capacity of your turbo and intercooler system. If the restriction of that can be minimised as I've done with mine, the behavior of the engine off boost becomes much more like that of an N/A engine and as such, the second point still stands.

[Gunni]

Throttle response?

Just only explain why? Throttle response in turbocharged engine depends of absolutely different things than in NA (capacity of whole inlet system, dimensions - or better weight - of rotating turbo elements, length of exhaust manifold, etc).

Better potential for air flow leading to more power for a given boost level?

Yes the air flow at throttle bodies wil be better but in inlet pipes between turbo, IC and intake to throttle bodies will be exacly the same. Also the speed of air near TB will be a lot lower which is not good for inlet efficiency.

Think those are two pretty decent technical reasons for fitting TBs to a turbo engine!

As above.
Jan

off boost throttle response is obviously the ticket,

The plan was to make a strong working NA engine that would then be converted to turbo, and throttle body was going to be matched to whatever size the ports could be enlarged,

a well designed NA platform will work better under boost then a stock NA platform before it,

IԚ´m not working on a 200hp M10 but something in the 400+ range,,
so it has to be very open,

the main thing tough is cause itԚ´s cool ;)

[Turbo-Brown]

a well designed NA platform will work better under boost then a stock NA platform before it

Agreed, if you can get a 10% better air flow N/A, the benefits will be further amplified by FI.

I should add that I don't totally disagree with what Yaninnya said but as a blanket saying that ITBs give no benefit on an FI engine statement I'd definately beg to differ.

As with all things, there's more than one way to skin a cat

[jaistanley]

Under boost the seals on the TB's spindles/injectors etc might weep, loosing boost pressure (and possibly causing damage/a fire). Especially on bike TB's. Not a reason not to use them, but something to be mindful of.

I think the statement that there is no reason to fit ITB's to a pressure charged engine is a little naive. The advantages to having them are reduced yes, but not totally removed.

The throttle response of ITB's also comes from the small volume of air between inlet valves and butterfly. This small ammount of air takes very little time to mix with fuel and hit the cylinder compared to a single TB/plenum setup. Advantageous in both pressure charged and n/a engines surely?

To a certain extent I agree that the ITB's could reduce the speed of charge flow at low rpm in a pressured charged system (as it also does in N/A) but the lower pressure drop offered might help combat losses over the rest of the charge cooling system.

Just my two pence worth.. As you can see, I'm on the fence a little. If I was to turbocharge my car I'd use the std throttle (unless it was tiny) for ease. If I had ITB's already and they were suitable for posotive pressure I'd use them for sure.

Jai

[Turbo-Brown]

I run unsealed TBs on mine and don't seem to suffer any ill effect.

Of course as the years roll by the wear in the bearings will become an issue but for the time being it's fine.

However, all the TBs I've recently designed have sealed ball bearings so they shouldn't ever wear out!

[Yaninnya]

The throttle response of ITB's also comes from the small volume of air between inlet valves and butterfly. This small ammount of air takes very little time to mix with fuel and hit the cylinder compared to a single TB/plenum setup.
Jai

You forgot that the injectors are in the same place so why will be any difference in mixing the fuel?
It is very hard for me to explain everything (I'm polish living very shortly in Jersey and my english is still quite poor) but I will ask only one question: why all top factory turbo engines (including F1 engines from '80) run on single throttle?
Jan

[Gunni]

Why does the SR20DET in the GTi-R use ITBԚ´s ???

[Yaninnya]

Why does the SR20DET in the GTi-R use ITBԚ´s ???

No, it is not on TB (from the factory, including GPA engines).
Jan

[Gunni]

?? My friend has one of those engines and it has itbԚ´s and another friend has a gtr 33 skyline and it has
itbԚ´s also from factory

[Turbo-Brown]

And how about the Peugeot 205 T16 rally car that featured ITBs and a big fat turbo?

[Yaninnya]

?? My friend has one of those engines and it has itbԚ´s and another friend has a gtr 33 skyline and it has
itbԚ´s also from factory

I'm enough old to remember GTI-R when was new (i.e. it was on 14" wheels!) and there was one TB. And here I see only one TB too:
http://www.uniqueautosports.com/Dyno/bmengine.jpg
Or I'm blind?

And how about the Peugeot 205 T16 rally car that featured ITBs and a big fat turbo?

I can't find any pictures but group B car was on single TB. Maybe someone later in rallycross convert one to ITB but originally was only one.
General note:
ITB are only for pulse (pulsating? I don't know the right english word) reasons in na engines, nothing else. With turbo there is in practice no any pulses at all.
Jan

[Gunni]

of course there are pulses as well in turbo applications, why wouldnԚ´t there be?

[Turbo-Brown]

So this GTi-R engine doens't have ITBs:



Or this one:



And you can't clearly see the linkage for the ITBs on this Skyline engine:



And this one obviously doesn't display exactly the same linkage?



EDIT>

And of course how could I forget the Bugatti EB110 which had a little 3.5litre V12, 4 turbos and 12 throttles:

[Scrotty]

Mr.brown smacks it

[robmarriott]

Under boost the seals on the TB's spindles/injectors etc might weep, loosing boost pressure (and possibly causing damage/a fire). Especially on bike TB's. Not a reason not to use them, but something to be mindful of.

Jenvey throttles are pressure tested, so this wouldn't be an issue with them, but I agree about the bike TBs, I'd have major reservations about using them for that reason, and the fact that they have silly secondary butterflys on some bikes.

Also, having seen people mapping with ITBs and a turbo, it's quite a lot more effort than with a single TB, for not a great deal of overall gain.

edit - I'm not saying it's not worth it full stop, it's just a bit more costly than a single TB mapping session.

[Turbo-Brown]

Jenvey throttles are pressure tested, so this wouldn't be an issue with them,

you say that, except that the jenvey sticker blows off given more than just a whif of boost!

There's really no reason at all why it should be more fiddly to map with throttle bodies and boost. Either set up a correction table to compensate for the fuel and ignition requirements of boost and map Alpha-N otherwise, or have the system switch from Alpha-N to Speed-Density depending on manifold pressure.

From the perspective of the person doing the mapping there's no real difference, only thing you might have to fiddle about with is settings for transient boost conditions.

[robmarriott]

Hmm, the Jenvey tapers I have have "pressure rated to 3 bar" stamped on them

I'll admit, I've personally never mapped anything, but a friend of mine works for a major Ford tuner, and their demo car was running a 1.9 8v with a T34 and 48mm Jenvey bodies, when they were setting it up they had trouble with the off boost to on boost transition on part throttle, but this is going back a good few years now (1997 I think), so maybe it was the turbo (now known to be a nightmare on an RS Turbo), or the lack of experience with the setup, or even the management not being able to cope properly

Either way, it's definitely going to flow more air and just work/look/go/sound better IMO.

[Yaninnya]

So this GTi-R engine doens't have ITBs:
Or this one:
And you can't clearly see the linkage for the ITBs on this Skyline engine:
And this one obviously doesn't display exactly the same linkage?
And of course how could I forget the Bugatti EB110 which had a little 3.5litre V12, 4 turbos and 12 throttles:

O.k. after qute long time I'm again on forum (just serious bike crash).
So please explain me (as you will explain 5 years old boy) why ITB are better on turbo engine?
Because you shoud know why ITB are so often used in na engines, do you? It is simple: pressure and vacum vaves, right? In na engine the whole story is beganing when the inlet valve is opening and the piston is sucking the air with the fuel in to cylinder. The vaccum vave is going back to the beagining of inlet (it must be very big diference of cross section). Right? When it is reaching this point it is changing the direction and as pressure vave is going back to cylinder. And the lengh of pipes needs to be so long that when the pressure vave reach the inlet valve port in this cylinder this valve shoud open. Right? After that this vave is pushing the mixture to this cylinder. And because the vave is moving with qute high speed (sonic) the inlet pipes needs to be very short so it is imposible to use single throttle.Thats the very short and extremally basic theory why in na engines ITB are working.
Now tell me how it can work in inlet with compressor wheel? You have the pressure (or lack of) in the whole inlet behind turbo. No pulses at all.
Can you explain me this?
I just prepared too many engines in the past to know what is working and what's not in turbo engines (just for the information that i'm not the master of computer keyboard I want to mention thet my engines won polish race championschip four times in the past - twice it was YB Cossie engines).
And please don't understand me wrong, there is absolutely no offence. I just want to explain some, let's say, inaccuracy.
P.S. I hope that all what I written here is clear. English is not my first language.

Mr.brown smacks it

Just Mr Yaninnya crashed on bike.
Friendly Jan

[Scrotty]

interesting point, as my knowledge is limited at this level, my 'smacks it' reference is to the 'which cars have tb's not single tb' array of pictures lol!
but id love to hear a few replys to the pulse theory thing...and learn
your english smacks it jan hope your okay after your crash

[Gunni]

Sound waves exist despite any pressure you may have.

N/A sound wave tuning has hot nothing to do with ITB´s,
It´s princible is only concerning the runner size and lenght,

ITB´s are for throttle response.

When the throttles are closed and you open them the air behind the throttle plate will be under vacuum, on the other side there will be 0vacuum,

This means that the air in the intake chamber is overpressureized compared to the air behind the plates.
That means that air pressure stabilization is quick as the volume is so big of the chamber,

now on a single TB setup, the whole chamber is under vacuum pressure while only the intake path is under 0vacuum, that means that the volume in the intake path will have to overcome the whole pressure diffrence on both sides of the throttle plate.

In short.

1 liter volume of 1bar absolute air pressure will take shorter time to rebalance a 0.25bar absolute pressure behind the plate where there is only 0.2L,,

While again 1liter of manifold pressure of 0.25bar absolute will take longer time to rebalance with 1bar air in the intake path,,

[e30world]

It will eventually be turbo so if that matters take that into consideration

There is no any technical reasons for fiting throttle bodies on turbo engine.
Jan[/quot
turbo m10 all reday don

[Turbo-Brown]

Holy crap, hope you're alright dude! The other guy came off worse though right?

Ambient air has a pressure, right?
And boosted air has a pressure that's ambient plus some.
How does that make boosted air different to ambient air? If you add 1/2psi to ambient air pressure, does that immediately eliminate any pulsing in the inlet system? All it does it increase the local speed of sound.
If you run a large ovelap cam with a nice free flowing turbo, does that eliminate the need for good air control?

[Yaninnya]

Much misinterpretation of more complex theories of the functioning of the internal-combustion engine (smart sentence, isn't it? Sad that thanks to translator ).

Sound waves exist despite any pressure you may have.

I'm not saying theat they do not exsist. I'm saying that you can not use them in fi engine. And the reason is very simple: for dynamic charge you need around 200 - 350 mm of inlet lengh (from inlet to valve seat). How you want to do it with fi? It is just imposible.

N/A sound wave tuning has hot nothing to do with ITB´s,
It´s princible is only concerning the runner size and lenght,

So how you want to design the inlet system in na engine with ca. 300 mm lengh and single throttle?

ITB´s are for throttle response.
When the throttles are closed and you open them the air behind the throttle plate will be under vacuum, on the other side there will be 0vacuum,
This means that the air in the intake chamber is overpressureized compared to the air behind the plates.
That means that air pressure stabilization is quick as the volume is so big of the chamber,
now on a single TB setup, the whole chamber is under vacuum pressure while only the intake path is under 0vacuum, that means that the volume in the intake path will have to overcome the whole pressure diffrence on both sides of the throttle plate.
In short.
1 liter volume of 1bar absolute air pressure will take shorter time to rebalance a 0.25bar absolute pressure behind the plate where there is only 0.2L,,
While again 1liter of manifold pressure of 0.25bar absolute will take longer time to rebalance with 1bar air in the intake path,,

If you are saying about na engine you are right but it is only side effect. The main reason is pressure pulses. I.e. in old BTCC or DTM cars nobody needed very good response (if engine was on throttle it was in 99.9% of time full open).
If you are saying about fi I will ask you one question: try to count the amount of air witch is flowing thru the engine in each second at say 4000 rpm and at 0.7 bar of boost. Quite mild condition but the result will suprise you for sure. And after this compare it with capacity of inlet from throttle to valves. You will be even more suprise.
All problems with poor response of fi engines are because of turbo lag. Have you ever driven the car with ALS? No lag at all and response without any delay.
Still frendly and no offensive Jan

[Yaninnya]

Holy crap, hope you're alright dude! The other guy came off worse though right?

More or less I'm alright. Only still have strange problems with short therm memory. And unfortunately other guy haven't even single scrach on the car. On one of blind crossroads (Jersey!) he was trying to pass but he moved his car to much. I pased his car but the manoeuvre was to tight and rear tyre lost the grip. Speed wasn't to high (I was doing 40 mph, officer! ) but after that, when I was roling I hit the wall. And I don't remember what hapened later. I "woke up" when I was lying on the tarmac. As Police adjudicated I'm not guilty (this other bloke will have lawsuit because of this accident) but bike is not exsistent (and it wasn't mine!).

Ambient air has a pressure, right?
And boosted air has a pressure that's ambient plus some.
How does that make boosted air different to ambient air? If you add 1/2psi to ambient air pressure, does that immediately eliminate any pulsing in the inlet system? All it does it increase the local speed of sound.
If you run a large ovelap cam with a nice free flowing turbo, does that eliminate the need for good air control?

I was trying to explain the bottom of the matter in my reply to Gunni. I hope that it is more or less in english.
Jan (frendly)

[e30world]

jap spaers not includet

[Yaninnya]

jap spaers not includet

Please mind that I'm not english. Can you explain what is "jap spaers"?
Jan