harvey

iTrader: (48)

Hi Richard :Thanks again for your help with the enlarged throttle body.

As with Richard, flow bench testing showed large differences between the runners and this work was done in conjunction with the cylinder head inlet tracts so the worst flowing were improved by the most possible while the best flowing were not improved by as much to bring flow rates per cylinder closer together.

The flow bench work was done after the extrude honing.

Floyds project is a useful starting point for anyone considering this sort of thing.

Nice spec Doug. good luck with it.

Cheers Mark.

dowser

Hi Harvey - completely forgot about that! Did you ever do a direct A-B comparison between the TB's?

Did you go to the trouble of measuring with valves in situ per runner when you did the heads too? This would be ideal, but would likely take days of flow testing

Richard

jasonius

iTrader: (1)

Looked for this in projects but couldn't find it.. anyone got a link please..?

Floyd

iTrader: (9)

https://www.scoobynet.com/projects-4...age-iii-4.html

Not Kev's though.

F

silent running

So port matching the inlet manifold to the gasket line is worth doing if I've got the time while the manifold's off anyway? And presumably the throttle body as well?

scoobysmiff

iTrader: (2)

i did my throttle body while it was off, the only problem i had is with the butterfly as i messed it up when knife edging it, it dont seal properly and wont idle correctly now, sits at 1.4k. No CEL so it has to be that, i have a new one in the post, just waiting to see it it rectifies the problem when i fit it.

IMO i wouldn't bother trying to knife edge the butterfly! lesson learn't the hard way there,
main reason is that they arn't available seperatly from the stealers so you will have to find one S/H or get one made up if you did as i have and sod it up

PICKLE

Did mine the other week. Left the butterfly alone.
Just ported out the entry from the IC side, and thinned out the spindle etc...



Going to fit before a little 'tweak' to the map in Jan as have been warned it may upset the current mapping! (non standard car though running fairly high bhp on standard motor)

silent running

OK so throttle body worth tidying up a little, what about matching the manifold to the gasket? I won't touch the inlet ports in the head for the moment, too worried about dropping swarf down them? Or could I port match THEM as well by stuffing the ports up with paper towels or something before giving them a bit of a going over? You can probably guess, I've never done any porting or polishing before, but how hard can it be?

I just don't want to find I've opened out the inlet manifold too much and then I lose torque or something like that.

evander

iTrader: (1)

To port a head you need to remove it and strip it bare mate, your not just matching manifolds. This isnt where the real benefit of porting the head comes from, at the very least you should be removing casting marks on the port throughts and sharp edge's and steps behind the valve seat area so the incoming and outgoing charge has a smooth transition from inlet to cylinder to exhaust manifold. At the end of the day its up to you how far you go but if it was me this is the minimum I would do, its forced induction so your only going to get so much from porting the inlet because the turbos doing all the hard work, dont get me wrong Im not saying this wont give you a bhp hike. You need to do the exhaust aswel, far more critical IMO than the inlet on a turbo engine.

hmhaga

I had this "porting" done to my throttle body:


Gave somewhat improved throttle response, no ill effects.

silent running

Well I'm more thinking of 'might as well' jobs to do while I'm there, not too bothered at the moment about getting right in there and working on the heads - apart from anything else, I think that's beyond my skill anyway, e.g. three angle valve seats and all the rest of it.

Although I am thinking of porting the exhaust manifolds as a project later on, which as you say should have a more noticeable effect. So sounds like it's best to just stick to working on the throttle body and inlet manifold and leaving the heads alone for the time being. They're STi 5 heads btw, if that makes any difference...anyone know what they're like as standard?

silent running

Looks good, I'll definitely have a crack at that. From what I can find out so far, the 60mm throttle plate is capable of the kind of power level I'm running at so at least I don't have to worry about enlarging it or anything.

Floyd

iTrader: (9)

Thread link now fixed: https://www.scoobynet.com/projects-4...age-iii-4.html

F

SLAB

iTrader: (77)

Why is it not a good idea to mirror polish the inlet manifolds

olliecampbell

iTrader: (3)

I believe so that it causes the air to 'swirl' on it's way in, which alloys for a better petrol/air mix in the chamber. I'm sure I'll be corrected if I'm wrong.

SLAB

iTrader: (77)

Any body else ive ported my heads but mirror polished the ports is it a good thing or as Slab done a bad thing

SLAB

iTrader: (77)

ANYBODY

maydew

iTrader: (9)

read somethin like this a while back if any help.
mirror polishing can cause fuel droplets
mirror Polishing the inside of your intake port may actually cost you some power. The slightly rough texture will help the air to swirl and to keep fuel droplets atomized and suspended in the air/fuel charge.

SLAB

iTrader: (77)

thanks m8y thinks i better get that 80 grit out