Budget powerbox for baby xe's

[Voodoo]

Anyone ever done one, or has any instructions on how to?
I've been searching through old posts on migweb, and saw something about adapting a Mk2 golf gti 16V manifold/plenum/throttle body as a powerbox? Any gen on this? I also got some ideas from the corsasport forums, but no in depth details. These manifolds are abundant on ebay, but there are different types, with different diameter runners and plenum chambers volumes (already did a little research on vw forums). Does anybody know which size is best? And would it be a case of just making a sandwich plate for the lower manifold and another for the tb? This would work a lot cheaper than any of the powerboxes out there!

[Stuart]

pick one thats got a volume similar to that of the engine that your fitting it to.

[Aragorn]

so all i need to do is create a box thats ~1600cc??

is that including the runners?

i was considering getting some 2mm plate and a TB gasket and lower inlet gasket as templates and making something similar to velos's torque tube which bolts on inplace of the original upper inlet manifold

im sure i read about matching the plenum volume to that of the capacity of the engine but i wasnt sure if this included the inlet runners?

do u know the advantages of a larger or smaller chamber?

at a guess i'd imagine an oversized chamber would increase midrange torque by slowing the gas speed, but might hinder top end power?

and the opposite for an undersized one?

also is there any advantage of using a cylinder over a square chamber?

[Stuart]

umm how many questions?!?!?!?!?!? lmao

get this months PPC with the cossie on the front, thats got an article about nome made plenums.

Look at motorbike air filter boxes, they will give you the best indication of the exact capacity to make it.

[Aragorn]

ideal stu

i'll nip into WHS tomorrow and grab a copy

Practical Performance Car right?

[Stuart]

i think it was practical performance classics, cant remember. but its got a D plate sierra cossie on the front

[Voodoo]

If the volume doesn't include the runers, then the golf inlet idea shouldn't work, because it's made for 1.8-2.0 engines. If it's the volume of the manifold minus the runners, then it might work. I know there are 2 types of inlets for the golf, one with 42mm runners and a bigger plenum, and one with 50mm runners and a smaller plenum. After cutting the runners off, the volume of one of them should be adequate for the 1.4-1.6 xe's.
The low down on using the golf part is supposed to be on corsasport, but I've been digging on their forum and only found generic info. This is sad, because golf manifolds are plentiful and cost peanuts, with a little fabrication, we could have cheap powerboxes!

[Aragorn]

in that case the volume must include the runners?

with the larger 50mm runners they'd need to make the plenum smaller to keep the total volume correct, which if what u say is true is exactly right

[Voodoo]

Aragorn, here's something from a vw forum, that confirms my theory, and also what you said previously about a smaller /bigger chamber moving the power/torque curves around:

"The 50mm manifold was introduced by VW in1986 because they had problems to reach the claimed 139HP with the small manifold. There was a strong public (motor press) interest in that topic VW was blamed to cheat the customers with wrong figures and they had to react. So they introduced the 50mm manifold. When catalytic converters became mandatory in Germany in the late 80's VW had to change the cams of the 16V to a more moderate version to protect the cat from getting too much unburned fuel. That is the main difference from the PL to the earlier KR engine. Due to the more moderate intake cam, the 50mm intake was
rather useless and even had a loss of torque at lower RPM.
So it was replaced again by the smaller 42mm intake. The max. HP figure of the PL engine was corrected down from 139 PS to 129 PS then."

So in conclusion, it seems it would be best to use a 50mm manifold with the smaller plenum to atempt a powerbox for a x14xe, right?
By the way, does anybody know the diameter of the runners on the x14/16xe intake manifold?

[Aragorn]

50mm is far too large for a 1600

im guessing they are talking about the 1800 or 2000cc golf 16v engine?

prolly around 36-40mm would be about right

the correct way to size it is to make the runners the same size as the inlet port (or slightly larger then taper them down to the inlet port)

and according to the PPC article the best size for the plenum is 200% of the capacity of the engine, it doesnt say if that includes the runners tho....

it has a phone number for some tuning bloke so i might give him a ring and query that :lol:

[Stuart]

was it the one with the cossie on the front?

i knew it was either a total volume or a "whole number" size larger but i wasnt too sure since its been a few years since ive properly thought about these things lol

[Aragorn]

yer silver d reg cossie

it doesnt really go into that great detail about it (its more an article concerning building an EFI system for a crossflow motor) but it says him and some otherguy did the maths and came up with the ideal size of 34mm runners and "for their application, dave walker said making the plenum 200% of the engine capacity would ensure they didnt see any of the torque defecit that small chambers create"

[Aragorn]

this is where things get annoying

a quick google found some refrences one to david visards book on inlet manifolds in which he says on a 4 cylinder motor u should size the plenum at 50-60% of the engine capacity as too large a chamber will destroy low down power (ie the exact opposite of what PPC said)

and a few other refrences said making it the same as the engine capacity was the best idea (although these gave little in the way of backup)

[burgo]

try the "megasquirt" forums there are some clever bods on there who make inlet manifolds all day long im sure they will be able to help you

[Voodoo]

Aragorn, you didn't get my meaning: My theory is to cut the runners from the golf manifold, leaving just a bit to attach to a sandwich plate, that will then bolt to the bottom 14xe manifold, kinda like a copy of the mantzel box. That's why I was asking the diameter of the 14xe runners, to check if they matted to any of the golf manifolds. Having in account our theory on volume=plenum+runners, the 42mm manifold has small runners, but a bigger plenum, and the 50mm has bigger runners, but smaller plenum. Considering the difference in engine capacity between the vaux engine and the vw, it would seem logical to use the smaller plenum chamber, follow so far?

[Aragorn]

yup but the standard runners on the original manifold are about 29mm and ideally they should be around 36mm