cswminty

Considdering getting a larger throttle body for my scoob and just wondered if the benefits outweighed the cost ???

If so what would you go for ??

Adam M

throttle response willchange, you may need a cammed throttle linkage to reduce this affect otherwise you may find the response of the throttle becomes decidedly non linear.

The way I see it is that I made 570ish bhp with the standard one.

This suggests to me that it didnt reporesent a significant restriction.

Am sure it would have had some effect in that the turbo would ahve to work harder, but I think there are more likely to be other areas to work on first, such as the intercooler pipework, before worrying about the throttle body.

cswminty

Cheers Adam, 500+ is something to aim at.

David_Wallis

thats bollocks.. you dont need a cam..

youve been listening to pat..

I run a 80mm tb with no problems..

David

Adam M

I have been listening to pat you are right, but equally I know that my engine has perfromed perfectly well without going to the hassle of a larger throttle body.

Wallis, given how long it has been since you drove the car, are you certain that the throttle response is proportional to pedal travel in the same way it was before?

MorayMackenzie

David,

To ask the question Adam failed to word nicely...

How does the larger throttle body behave at small throttle openings when driving in traffic etc?

cswminty

And....... having up-rated my ...Turbo, intercooler, injectors, exhaust, ecu, air filter, fuel pump, FPR.....would you up-rate this next ?

P20SPD

iTrader: (1)

Er, am i being over simplistic here, or are you guys complicating things?

If when the pedal is fully raised, the throttle body is fully closed, and when the pedal is fully depressed the throttle body is fully opened. Assuming the car has then been mapped subsequent to change, ie to take account of additional air available, then why would throttle sensitivty be affected?

Steven

P20SPD

iTrader: (1)

cswm - suspension and brakes if you have not already.

also inlet pipe?

[Edited by P20SPD - 9/11/2003 11:47:56 AM]

cswminty

HKS, suspension has also been added, along with 18" Prodrive's with Toyo's.....The brakes will be done ASAP and i'll take it steady until then.

Its off the road at the moment so i may get new brakes before i venture back on the tarmac.

cswminty

Steven , how do you mean the inlet pipe ? samco etc ??

P20SPD

iTrader: (1)

Inlet pipe, is generally classed as the section from the maf housing to the turbo. Replace with large bored pipe and smoother corners, eg MRT/AVO/BPM etc.

Steven

cswminty

Yeah i thought that was what you meant, i might see about gettin something fabricated, although i was looking at those air filters like Davids that could supply a Jet engine so i may see what diameter one of those would need and maybe go that silly also.

P20SPD

iTrader: (1)

Do you use the MAF sensor or not, i know you say you have changed ecu, but that could mean just mapped. If you dont, i will try and post a pic of mine up for you, similar filter to Davids, but using the standard path to the turbo

Steven

cswminty

The scooby is in pieces..literaly...the engine is out for a complete re-spray and the roll cage to be welded in.

I have yet to put all of the new pieces back on the car i'm just collecting many new parts. I have an APEXi power FC to fit and get mapped, so i'm unsure about the MAF yet, think i may be able to remove it ???

P20SPD

iTrader: (1)

Not sure about the apexi FC, would guess it still needs the MAF, may be completely wrong though.

Steven

The Fixer

Steven,

You are quite correct in your statment above but throttle sensitivity is altered because the % of charge going through the throttle body has increased for the amount of travel on the "Go pedal" I think I have worded it correctly

P20SPD

iTrader: (1)

CSW - need to take them first ;-)

RSVR - i follow that, but my point was, that if it had been mapped around, then the sensitivity would be in the same proportion to the engines improvement, surely? Also, i would have thought that you naturally adjust your driving, again taking a simple view

Adam M

RSVR has it spot on,

it isnt a mappign issue.

the problem is that when you want to open the throttle a tiny amount, your control over the larger opening simply isnt as fine, in effect the resolution of the throttle pedal to rpm has gone down.

All the map does is make sure that the fuelling and timing is correct for every load point.

It cannot stop the car going to 4k rpm just by raising the throttle very slightly away from idle (exaggerated to make the point).

P20SPD

iTrader: (1)

Ok, think i see what your saying, so the solution is?

Learn to drive without using a lead foot?

StevenD:

Adam M

use a cam on the linkage betweent he throttle opening and the translatory movement of the pedal so that a big movement at the beginning of the throttle pedal travel, does little to the throttle valve, but does more and more as you approach WOT.

This is what Wallis originally said was unnecessary.

P20SPD

iTrader: (1)

Why though, surely you can learn to drive around it.

Recently i had a leak on my inlet manifold, in so far as when i touched the throttle and i mean resting foot on pedal, revs shot up to 1800, take foot off and it would take 5 secs to go back to normal idle. Also whilst brakcing the engine did not want to go below 1800 rpm.

Therefore when i wanted to set off as per my normal foot position, say 2000rpm, it would actualy be 3000rpm! So setting off i just did not touch the accelerator until moving. Wjilst braking i put my foot on the clutch once revs got to 2000rpm.

Did not last long, approx 500 miles.

I simply adapted my driving until the problem was fixed, simple.

Steven

cswminty

What a can of worms i have opened........I am fitting a new clutch and lightened fly wheel so that will need adjusting to anyway, so if it is just a case of changing the style and getting used to it ......

David_Wallis

Adam,

You cant really talk about having cars off the road...

Mine was due to lack of licence.. yours is down to lack of common sense

David

Adam M

why did you loe your license again david? and to make matters clear, I am waiting before the monster engine goes in so that I can get used to it again!




steve,

agree, you can drive around it, but I would expect it to change the "feel" of the car.

Wallis has done it

P20SPD

iTrader: (1)

Adam, sure it will change the feel of the car, after all wouldnt you do it to improve the cars feel/performance?

CSWM, Depending on clutch and flywheel you may not have to adjust style, i didnt when i changed mine.

Steven

Adam M

admittedly, my clutch means that for lower engine speeds I woudl be better off if it jumped straight to 2k rpm, as no matter what I do constantly attempt to make it as smooth as it always was.

I mentioned to harvey that it drove i the same way as the standard clutch, but havign had a little more practice, the only downside I find is that it doesnt hanging around the biting point. it is far smoother if you just give it a few more revs and decide one way or another.

Steve, I am not convinced that the restriction is that big a deal.

My headers on the dyno had about one inch length of 2 inch diameter, and these did not seem to get in the way of the power figures at all.

Am sick of creating more and more problems whilst reaching for extra power.

I am convinced I have more than enough in a car weighing under 1200kg, to last me quite a while, adn by the time it isnt enough, I will want an audi rs6, in the same way as Cem does.

cswminty

The flywheel is 4.5kg. so from what i have read it will be drastically diff.

cswminty

Steven the pictures would still be appreciated tho if you dont mind...

Cheers Chris.

PS> fire em down the e-mail to me at work if you like chris@1ct.com.

[Edited by cswminty - 9/11/2003 1:38:53 PM]