Author Topic: 8v crossflow questions....  (Read 4758 times)

Offline spankier

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8v crossflow questions....
« on: 11 March 2009, 15:44 »
Right, first off, im new so hi everyone.

im planning to put my throttle bodies on my mk2 at some point this year (funds allowing) but its got the ev (k-jet) head on it with the counterflow design putting the inlet in a hot/cramped area, so i started looking at the mk4/beetle 2.0 crossflow motor instead, and its raised a few questions...

will my mk2 engine mounts fit on the later 2.0 blocks the crossflow heads came on?
likewise my mk2 8v tubular manifold- will it fit the head?
can i use cams listed for the ev/pb engines in this head (im not re-using my current one but i cant find any specifically listed for the crossflow)
ive heard rumours they had smaller valves than the mk2 8v GTi's, is this true?
and finally does anybody know any crossflow engine codes? ive been searching for ABA info but i think there are other codes which are for different compression ratios(obviously the more the better for me)

thought id tag on the end..... im well aware of the wonderfulness of the abf 16v but it really all boils down to money, being a compulsive tinkerer, and what fits that ive already got so if the exhaust maniflold/engine mounts dont fit ill probably change my mind, but if they do ive only got so save up for one cam, fit my homemade vernier pulley, and do one of my infamous portjobs before i have to worry about the throttle body fitment/ engine mangement side of things- with a valver its 2cams, a timing chain, an exhaust manifold, and another very long afternoon making a pulley or the money to buy one, plus ive never ported a valver before so although i understand the principles id just be happier using what ive learnt already.

as for using the whole engine i want to keep mine intact for two reasons 1) i have a recurring daydream about a 2litre prefacelift polo coupe, and 2) my blocks already seen plenty of action, iknow theyre tough but i dont want to build it twice....

Offline Ben Lessani

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Re: 8v crossflow questions....
« Reply #1 on: 11 March 2009, 19:10 »
Pm DiamondHell - he's running a Xflow on his car atm (might even be selling it)...

... you won't like it, but he has squeezed all he can out the Xflow - but has given up on it and just moved onto the ABF, its the most sensible decision - considering you can pick up a whole MK3 for around £180 - half the price of an average cam.

Offline Diamond Hell

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Re: 8v crossflow questions....
« Reply #2 on: 12 March 2009, 13:07 »
There's still a touch more to come out of my crossflow before it comes out, Ben - got Megasquirt to fit to it and we'll see how we go.  Once that's dyno-ed it WILL be coming out and having the ABF nailed in there instead.

will my mk2 engine mounts fit on the later 2.0 blocks the crossflow heads came on?

Mine's on a 2E block and the mounts are the same.  Some people go on about the motor being too high, I've not encountered this issue.

likewise my mk2 8v tubular manifold- will it fit the head?

Flange is right, but check clearances on the 2.0 (same as a counterflow).

can i use cams listed for the ev/pb engines in this head (im not re-using my current one but i cant find any specifically listed for the crossflow)

As far as I'm aware counterflow cams fit to crossflow heads and vice versa.

ive heard rumours they had smaller valves than the mk2 8v GTi's, is this true?

Can't recall about that, but remember that the crossflow head is on 1.6 and 2.0 VAG group petrol motors, so there are going to be a range of detail differences from engine code to engine code, including gas recycling ports on the exhaust side.

The common issue with the crossflow is that you'll need to weld up and re-drill the oil return to drop the oil back into an earlier block - the position is different to the counterflow.  An ABF headgasket fits right up once that's done.

For reference, with mine running a crap map, and a 268 cam (IIRC) on digiII I got 130bhp on a rolling road.  The crossflow allegedly flows about 15% better than the counterflow, so you're winning...... right up until you realise how good and cheap ABF motors are.
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Offline spankier

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Re: 8v crossflow questions....
« Reply #3 on: 12 March 2009, 19:27 »
answers! wahay! and thank you!

im currently runnig the AGG bottom end (same as 2e?) with a home-ported EV(k-jet) head and a piper or kent (cant remember!) 276 degree cam, with a mildly bodged kjet system and nasty kjet type dizzy, still got a few mods to go on this motor but its actually not bad at the moment, ran a 15.6 second pass at santa pod last year which is nothing incredible i know but ok for what it is.... anyway the point is im only after an engine with ports on the front of the head because i accidentally bought some throttle bodies on ebay thinking they would only be fit for the mantlepiece (fair enough at the price i paid) and theyre like new-result- and im planning to take my time building the engine and getting the bits i need to do the swap.

i would just look for the head and bolt it to my block + repeat existing mods but it would be a shame to split this one when it would be ideal for a polo sleeper or a caddy or something, which was what led to the engine mount question, although if i buy an engine and they dont fit i could just buy another agg bottom end for cheap and mate it up to that- how far different is the oil return? is it offset a bit or in a completely different place? ev oil return is on front of head between 2+3 cylinders iirc although i may be getting confused (took a LOT of stuff to bits last year- dont ask!)

have to say i was expecting you to have found a bit more than 130hp..... is it a newman cam youre using? i tried one and it was great for torque but killed the revs dead at about 5,200 rpm, tried everything and ended up with a lumpier bump stick which helped, but only a little, carried on tinkering, like you do, and the last thing i could think of to try  was waisting the shafts in the throttle body to increase cross sectional area/decrease turbulence..... and..... it worked, brilliantly, pulls hard all the way to 6,300 ish now and flowed enough extra air to need another fuel pressure increase/ mix adjust dont know what manifold/ throttle body combo you're running but try reworking/enlarging if possible, the head may flow better but if the manifold doesnt it wont make any difference at all (just look at the bmw 323/328s, shocking!)
not trying to tell you how to suck eggs or anything but it workeed wonders on my counterflow even with the stock manifold on....

http://www.atpower.co.uk/atpower_gallery.html

thats where i got the idea- those throttle bodies actually use the throttle plate as the shaft (look for the pic pointing down the bore) obiously you have to leave the screws in and enough shaft for them to go int but theres still lots to go at, i can whip my intake off a post a pic of mine idf you like?

gas recycling ports... ooer! i know what egr is but never actually worked on a motor with it fitted, how different are the ports?

and the abf, my mates got one in his mk1 and i love it, its the next option if i decide against the crossflow.... but.... as it stands ive yet to be put off it, ive read hundreds of arguments on the 8v vs16v argment and the fact is a 16v will always make a car faster than its equivalent 8v, but im sticking 8v for a while for 2 reasons, 1) once ive got a suitable management system im going to be tuning for economy at part throttle as much as power at full throttle as i cover lots of miles (parents live in france about 12 hours on the motorway) and the swirl/tumble characteristics of any 8v make this easier to achieve than with a 16v and 2) stupidly, i just like 8valves- reasons/excuses/bullsh!t aside, i just do. i like 16valves too, i just sort of default to 8valves, i think modern so called eco cars should be 8valve too but i digress....

anyway thanks again for the answers, and sorry for asking more and banging on for ages

Offline Diamond Hell

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Re: 8v crossflow questions....
« Reply #4 on: 12 March 2009, 22:20 »
The oil return is not a big move, but should be done - check if the AGG uses an ABF headgasket - you may find it's late enough to have the return in the right place - I'm not certain on that.

If you're going to use bike bodies then I have a mate who makes these:



PM me for contact details, if you want.

I have more than 130bhp now and there's a bit more to come - the map on digi2 was balls.  I have an ABF throttlebody and Megasquirt to fit, which should sort things more.
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Offline spankier

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Re: 8v crossflow questions....
« Reply #5 on: 12 March 2009, 23:08 »
flange looks smart- im a cnc miller by trade and my mates a coded welder/fabricator so if we cant come up with something between us we need sacking, but ta for the offer!
moving the hole shouldnt be a problem either, ill havr a check on head gasket part numbers- rumour has it that abf/agg blocks are the same but rumours dont strip cars and mend them in the rain....

how are you getting on with mega squirt and which version are you running? and most importantly have you found a rolling road who can tackle it (and is willing) ive been looking at the emerald system for the throttle body build purely because the interface on the computer looks so simple to use- i read the mega manual and decided i needed to do a bit more computer learning but that was a while a go now, one of the next mods im planning is to fit the megajolt (similar to megasquirt but spark only) to my current engine, partly because dizzys with weights and sucky pipes have had their day, and partly for practice, plus if i can get a useable map it should work as a sensible starting point for the next one.

im rambling again.... would be interested to see how yours evolves if thats ok? mine will take a while as im currently in france till may and need a job in a hurry when i get back to the uk, but at least i know what to aim for now. thanks again for the info.


Offline WYATT

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Re: 8v crossflow questions....
« Reply #6 on: 14 March 2009, 21:41 »
did you make the manifold?

Offline Diamond Hell

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Re: 8v crossflow questions....
« Reply #7 on: 14 March 2009, 23:11 »
The manifold was made by a mate, for a project I'm mucking about on.

That was his first attempt on one  :wink:

Spankier - watch this space.  Lots of interesting discussions at Goodwood yesterday (and finger graphs drawn on my bonnet for illustration) about air/fuel ratio and why my car is bogging slightly 5-6k and then picking up as it heads to 7K.  This is definitely pushing me to get the Megasquirt on there ASAP to see if we can't liberate quite a few more ponies and give the engine a whole load more kick.

Squirt will be V2 and will be base-mapped, then taken out and explored on road and then put on InterPro's dyno for final tweaks.
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Offline spankier

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Re: 8v crossflow questions....
« Reply #8 on: 16 March 2009, 22:01 »
hahaha its can be really frustrating getting one part of the revs right and another wrong.... took me about 6months of googling for info, tinkering for hours, and asking for favours to make my k-jet behave, satisfying tho! does the v2 have a target lambda function? or do you have to do it via the ve/pulsewidth table? im looking forward to doing the spark control on mine- should see better low end/part throttle power as my lumpy cam will be killing low speed cylinder filling and vac advance for a double whammy of letdown.... running plenty of cam advance has helped but at the moment the best way to save fuel is to get where your going as fast as you can so it gets turned off sooner, not the approved method!