VR6 big bore throttle

[dinkus 10]

Quote of the week there? :lol:

[TREVR6 0]

Can I just say how impressed I was also with Alpina's tb. Got one recently and was very impressed with the quality and service, thoroughly decent chap.

Made a fair difference too, and she is in for a remap on Saturday, I'll keep ya'll posted!

[Kevin Bacon 5]

Ian is a top bloke. I've met up with him twice now and he REALLY knows his stuff. And he has an extremely nice E46 M3 8) He gave me flowed Golf and Corrado bodies to play with and I have to say, the flowed 2.8 body (has a hump in it for more progressive action) is absolutely awesome. It also has a lighter spring so the throttle response is absolutely instant. You can lift your foot off the clutch and the car will pull itself along on idle, which I couldn't do before with a 2.9 body. Midrange and bottom end is phenomenal.....it really wakes the engine up.

[dr_mat 0]

How can a throttle body effect torque at idle? I though zero throttle = closed throttle?

[Dutch24V 0]

So your problems below 2000 are solved then Kev? Cool...

 

...is the 2.9 in the post then btw? :wink:

 

"You can lift your foot off the clutch and the car will pull itself along on idle, which I couldn't do before with a 2.9 body." Hmmm, I can no problems?

 

Dutch

[Kevin Bacon 5]

How can a throttle body effect torque at idle? I though zero throttle = closed throttle?

 

Have a look at a Golf throttle and work it out for yourself.

 

And if the throttle was totally closed it wouldn't idle.

[dr_mat 0]

Have a look at a Golf throttle and work it out for yourself.

 

And if the throttle was totally closed it wouldn't idle.

 

Thought the ISV bypassed the main throttle butterfly. Or are you (not) saying that the Golf does it differently?

 

When I stumble across a Golf throttle in my cupboard under the stairs I will indeed work it out for myself.

[Kevin Bacon 5]

No the ISV is an idle stabiliser, hence it's name, air still gets past the butterfly in both Golf and Corrado applications. Hold the throttle up to the light and you'll see light through the gaps around the butterfly.

 

Do you ever actually take an interest in people's threads as an enthusiast, or is your sole purpose just to be pedantic, sarcastic and arrogant?

[dr_mat 0]

Jeez, take some happy pills Kev. I was only asking cos I didn't know the answer!

 

I'd never assumed the main throttle butterfly was totally air-tight, but that it was more or less closed. I'd assumed the ISV's role was to totally control the idle airflow, which it does using it's own solenoid-activated valve.

 

Was I wrong?

[Taggart 0]

Kev - did you swap him a 2.9 TB for a 2.8 one?

 

If everyone does this he's gonna end up with a shed load of 2.9 TB's

[Kevin Bacon 5]

Mat, I was working on the car until 2am this morning and I'm knackered, I could feel the differences immediately, so I didn't appreciate it being questioned..... but yes, you're right, that's what the idle valve does...it stabilises and it's also known as an idle filler. In the good old days you would simply drill a 3mm hole in the butterfly, or leave it open slightly....but emissions controls required leaner and leaner idling....so the ISV was born.

 

The Golf TB opens against a ridge at the bottom, so where the 2.9 body would be open top and bottom when you start to press the gas.... the Golf one is only open at the top and then gradually the gap at the bottom increases....this gives more progression, but the cfm is the same as the 2.9 one. And it works really well in the C, totally removes that lazy feel below 4000. Sometimes things just work, without the need to over analyse them :wink:

 

I'm now popping my pills.....

 

Xbones, the 2.8 body is still in it's trial period at the mo but yeah, ultimately he'll get my 2.9 one back if I decide to stick with the 2.8 one.

[dr_mat 0]

Ok I see, yeah, I can imagine you're a bit knacked .. :)

But I guess it's all worth it, hey?

I like the idea of the throttle body swap myself, having gone the VGI route I see it as a "free" (as in speech) performance boost, and anything that improves driveability can only be good on the VR ..

[Dutch24V 0]

...Got my enlarged 2.9 TB today.

 

Cheers Kev - will probably fit it tonight and post results tomorrow...

[Kevin Bacon 5]

Good stuff. If you're happy with the way it drives at the moment, just swap the throttles over without resetting the ECU as you're using the same type of TPS, so there's no need to reharmonise the ECU.

 

Otherwise you'll need to fun through basic settings.

[Dutch24V 0]

...was wondering about that!

 

Cheers for the tip - literally plug'n'play then, which is nice!!

[Kevin Bacon 5]

Aye, I found the engine better just swapping them over. Going through the reset etc was unnecessary and made the engine worse to drive on part throttle.

[Dutch24V 0]

The TB gasket I have from VW is metal and has a small groove running round the circumference that is raised one side and sunken the other.

 

Stupid question: Which way round should I fit it?

...and should I grease the gasket before installing or just wack it in??

 

Dutch

[Kevin Bacon 5]

It doesn't matter mate, either way round......

[Dutch24V 0]

ok, thanks - and just wack it on or grease it first??

[Kevin Bacon 5]

Just whack it on, no grease!

[Dutch24V 0]

nice one, cheers mate...

[Dutch24V 0]

Well, it's fitted and... :lol: :lol: :lol:

 

Works perfectly Kev and still has a very progressive throttle! 8)

 

It seems to free-up the engine a huge amount and she pulls noticably harder accross the rev range, particularly from below 3000 rpm. The induction noise is a little more noticable too, but not in a nasty sounding way

 

The idle is much stronger like you say and it is indeed easier to drive on it for some reason!? The spring feels a tad firmer than on my previous body also and dropping to idle is far more solid.

 

For 125 quid ex. you can't go wrong!!

 

Dutch

[Kevin Bacon 5]

Good aren't they! My engine pulls MUCH harder with the throttle body too.

 

I'll be getting another when Ian's back from holiday.

 

The throttle springs should be as per stock or lighter on the new one as Ian fully rebuilds them with new needle roller bearings and seals.

 

The standard ones tend to get stiff with age.

 

Well done mate, was a doddle to fit yeah?

[Dutch24V 0]

Yep, very easy mate, even for a novice mechanic like myself!

 

The mechanism itself felt 'stronger' and more solid than my old one and the pedal feels just a little firmer. Not a bad thing and certainly not stiffer if you get what I mean!? :?

 

The pedal now stops about 5mm from the stopper on the floor though so if I push the pedal too hard on full throttle it stetches the cable a bit. Should I adjust this or just develop a lighter right foot??

[Kevin Bacon 5]

No you need to adjust that. There's a little circlip behind the rubber grommet that secures the cable to the holder on the throttle. Remove the circlip then slide the cable forward a couple of notches, and then replace. With the bonnet open, you can peer through the gap whilst pressing the throttle and observe it's movement. Press the throttle up and down and listen for a click as it hits the stop at rest, and also when it reaches max travel. When it hits max travel that should coincide with the pedal hitting the stop on the floor.