doug2507

iTrader: (6)

Hi,

Is it worthwhile porting the inlet manifold or would this have adverse effects? I've also noticed the casting is a little rough with seams from the casting process running along the inside and wonder if its worth rubbing these down. Would the surface need to be left rough after this for aiding gas flow?

Secondly, would it be worthwhile grinding down the butterfly in the t.b. between and outside the securing screws?

Cheers,
Doug.

PICKLE

I cut down the butterfly screws on mine, thats all.

Just made them 'flush' when the throttle is open. Every little helps I suppose?

Interested to hear from some experts on this..

doug2507

iTrader: (6)

Well its just from 'mini' (a-series) experience that i started to wonder. The guru of mini's- David Vizard, recommends tidying up the inlet manifold and porting it but not polishing it.

He's also got some tips on the butterfly for s.u's/webber/dellorto's for a bit better flow and thought it could be applied to the throttle body on a scoob.

As you say, every little does help. Even if its minor, all the minors add up to the major...Building the engine myself so looking for some 'tips of the trade' to get the best from it and more importantly, hold together!

David_Wallis

if you do **** around with the butterfly, make sure the screws are either split, or thread locked..

And porting the inlet manifold isnt happening without a bandsaw and tig welder..

However if someone wants to buy a Inlet manifold with a 70mm Throttlebody, I may be interested in selling it

olliecampbell

iTrader: (3)

Theres actually a load of good posts on www.naisoc.com about this, with photos everything.

Meant to be a really really good cheap mod and gives you better throttle response

doug2507

iTrader: (6)

Reasons/method..?? Thought it would be simple enough to do with a compressor and the right grinding tools?

Butty

iTrader: (2)

You can't port properly beyond about 3-4" up each runner other than cutting the thing in half and getting stuck into the main chamber.
The effectiveness of this tickling (rather than 100% porting) has not been measured to my knowledge.
But if you have the time and tools then why not? I find it theraputic if nothing else.

Nick

doug2507

iTrader: (6)

Cheers Nick. So in your opinion would it do more good than harm or should i just put the idea out the window?

The heads are going to get reworked anyway so i thought i may aswell open up the ports of the inlet manifold aswell. (using gasket as a guide then blending in as far as i can).

p1mark

IMHO if its on its own then its not worth it. If however its part of a full look at/clean/up of the whole intake tract (in particular the ports) then it probably is worth it - in particular for a competition engine.

As David says, you cant port it as such, its more of a clean up. Just remove the rough finish and pay atention to the ridges on the casting split. clean up as deep as you can with your kit but dont bother polishing

If you are not careful you can do more harm than good - the key is to ensure you get a good match to the head. The way to do this is get your built engine with the ported heads built on. Put a good smear of engineers blue on the mating face of the heads then drop your manifold on minus the gaskets.

Then take it off and port to the blue marks and it will be a perfect match.

There is a way you can do the whole manifold. the name escapes me at the mo but there is an abrasive putty avaliablie that you force through any aluminium aperture and it smooths it all out. Have used it on cylinder heads in the past (on mass produced engines i.e ones that it would be too time consuming to manually port) and it works well. Not cheap but i can get you info if required.

The same goes for knife edginging the leading edge of the butterfly and fettling the screws. On its own not worth anything but as part of perfectly matched and smooth intake it would be just another one of them things you do.

As said above its a cliche but every little bit does help, Pickle could do with about 4 BHP to get him over the 400 marker so he should get fettling

doug2507

iTrader: (6)

Well, i'm building it for hillclimbs/sprints and want to build it to the highest std i can without chucking stupid money at it so every little bit helps IMO. I'm not in a rush to complete it and believe in spending a little time and effort to get things spot on. Even if this does mean asking daft questions and feeling like a tw*t later.... Cheers for the advice guys....

911

Flat4 (Kev) on Projects did a good write-up as usual on his body and I think the Y piece on the TMIC, smoothing all the way.
Could be worth a look?
Graham

doug2507

iTrader: (6)

Cheers Graham...

harvey

iTrader: (48)

Much as P1Mark says above.
The process he refers to is "Extrude Honing" done by a company of that name in the N.Y area of the US. Taking into account transport cost to and from the US, I am not sure it is viable unless you are looking for every ounce of power.
Having ported several throttle bodies, I am not sure it makes an identifiable difference but "many a mickle maks a muckle" Reducing and flattening the TB spindle has to have some bennefit and if you already have the thing off and have the time you have little to loose.

The inlet manifold on its own probably makes little difference but if you are careful, again there is nothing to loose. With ported heads I think there are probably greater gains to be had.
My objective is to remove any step between I/M and head inlet tract, smooth out tight bends and take off roughness but not polish to a high degree. With a flexi drive you can get well inside the I/M but even extrude honing only cleans the surfaces that are exposed to the flow.

On an average build these items would be low down on the priority list as there are bigger gains for less effort elsewhere.

doug2507

iTrader: (6)

"many a mickle maks a muckle"

My thoughts exactly. More so on a n/a engine i suppose but every little helps and when it only costs you time you cant go wrong really, according to above posts.

Apart from machining, there's no costs left for my build (apart from maybe a new box/fr. diff) so i aim to make the most of what i've got.

Engine spec:

2.5 built. (LP rods, mahle pistons, cometic gaskets, arp bolts, race bearings etc blueprinted/fully balanced)
V6 heads + valvetrain (matched for 2.5 and ported/polished)
TD06-20g (possibly change to a 49lb?)
Grp.A oil feed
Apexi pfc +avcr/defi's (maf bypass from Andy?)
hks fmic + i/c spray
hks headers (ported/wrapped)
aps DR exh. (3.5" with high flow outlet-does this need modified?)
H+S up-pipe
SX fpr + walbro (will i need bosch?)
hks 740 inj's
Billet fuel rails (once Carl gets them in production!)
Manifold spacers
MRT inlet + K+N/airbox
RCM pullys (no a/c)

Drivetrain:

V6 Type R WRC box (looking for ppg next yr.)
DCCD with programable controller (neetronics)
R180 rear diff/shafts/hubs
Std (vicous) fr. diff (poss. change for atb?)
Exedy twin plate & F/W
Grp.A gearlinkage

Chassis:

Stoptech 330mm disks/4pots
std 2pot vented Type R rears with DS2500 pads
Braided hoses f+r
HKS struts
Poly bushes f+r/subframe/diff lock
Whiteline d/links
GT-spec alk
f+r upper/lower strutbraces
Quickrack + Grp.A fixings
17" with sticky boots
Cage (on the shopping list)
Prodrive/recaro Profi Sp-a buckets
Harness's

Sorry for the bore attack with the spec but if you've got any points feel free to chip in...Cars for hillclimbs/sprints

stevebt

iTrader: (8)

i know its more money but flatfouronline do the magnus intake for £800 delivered to your door !! been tempted to get one myself but i dont know wether it would make my car worse on a 2ltr engine !!!

doug2507

iTrader: (6)

"Proven to make over 40 hp at the wheels on the Impreza"

Find that one hard to believe...

Think i'd only contemplate spending money on something like that on a 2.3/garret build for the 1/4 mile.....

doppelganger

you could put a switch in for the alternator.approx 3-4hp according to a mate who works on subaru rally team.ive done it on my drag car (ok its a scooby lump in a beetle but 12.95 @108 from a legacy turbo) .and you can hear the difference in engine tone.and its free hp barring the switch and wire

p1mark

Nice one Harvey - extrude honing!

and the actual name of the product is extrudehone rather oddly!

Was quite impressed, just running it through a 16V inline 4 bike cyl head (inlet side only) gave 3% increase IIRC in CFM on the flow bench. not as much as a proper porting job but still worth while.

PICKLE

Mark,

Floyd

iTrader: (9)

I ported my TB and detailed the process with photos on my project thread.

Thanks chaps for remembering my hard work here I also took my ideas from DV circa 1980's so nothing new here or on NAISOC!

I didn't do the extrude hone thing as I couldn't find anyone nearby to do it. The manifold isn't that bad anyway for medium power increases and there wasn't anything obvious to be done in there. Matching to head is obvious though and it can be done in situ if you're brave (Andy Fuzz)...

F

p1mark

Anyone interested in refining the inlet system should look at Floyds thread in projects. Undoubtedly the phrase "many a mickle makes a muckle" can be shown in a practical application when you look at what he has done and the BHP/Torque/Driveability achieved

Callum Ferguson

iTrader: (1)

[QUOTE=doug2507
aps DR exh. (3.5" with high flow outlet-does this need modified?)
[/QUOTE]

I found quite a bit of misalignment between the exhaust housing and the APS outlet so it could be worth checking this out.

Good luck with the project.

Callum

doug2507

iTrader: (6)

apparently that big chunk of metal needs to come out..

Cheers Floyd. Think i'll go stick the kettle on...

Floyd

iTrader: (9)

Marky

MAMMAM phrase stolen from Andy F in my thread

I could have slimmed the butterfly more but I didn't want it to break and get sucked in

F

doppelganger

what size are impreza throttle bodies ,because ive measured up a load today from 2.2 legacys and a 2.0ltr legacy turbo and the o/d is 70mm??

Floyd

iTrader: (9)

Doug, did you get my last PM?

F

doug2507

iTrader: (6)

..no...

doug2507

iTrader: (6)

Just had a look through your project thread Floyd. It really is quite good and very helpfull as a reference/guide.

ElusiveStranger

Hi guys.
I'm new to the Subaru game. I'm putting an EJ20 into a '78 VW Bay window camper.

Thought this may be of some help here
http://www.vwkd.co.uk/bb/viewtopic.php?t=241
There's shots of my manifold before and after match porting. The head inlets were pretty spot on to the gaskets with the bolts in place.

I know on carbed engines it's better to have a rough(ish) finish as it helps keep the fuel in suspension through the manifold. Well that's what the theory says

dowser

I used Power Porting in Australia to do the work, much cheaper than extrude hone...even with shipping to Melbourne and back. Flow rates between runners are significantly different before he started, and within a few percent of each other afterwards. Check my 22B projects thread for more details http://bbs.22b.com/cgi-bin/ultimateb...2;t=000011;p=2

They also enlarged TB by 12% at same time. Not sure what difference it has in isolation, as it's bolted to an EJ25 with lots of other work done too. Overall package will be finished in the next few weeks

Richard