Polo 4.2 V8 Transplant

[Lee]

Yes saw that and his comment about blow off compared to butterfly valve was interesting.

I was working on the car today and it runs but only at 4000rpm--this with the bypass valve wide open.

I cannot figure out why when the engine is running that if I pull the the vacuum line off the bypass the revs drop .

by putting my thumb on the v/line the engine can be reved as if the throttle has been opened.

Have I a air leak ??

[80 Vert]

Post some pictures of that area Lee, might help us understand better how you have fitted the valve and where.

[mark2 golf]

Isn't your you bypass valve your air leak. Or am i missing something. It being open is effectively another throttle that's why its at 4000rpm

[80 Vert]

What I was thinking...................hence having it before the T/B but then without seeing your set up......

[Lee]

I'll put up some pics tomorrow

[80 Vert]

Just re read your original post and your set up is what I have on my 05 Mustang, air in through T/B, through S/C through intercooler into engine.
In theory you don't need a bypass valve as the throttle body doesn't see any boost at any time, its purely there the meter air going in.

I was thinking about having an external S/C or Turbo hence the need to bypass boost when T/B is closed which is why you'd need a valve.

[M]

I agree with John. If the tb is before SC what are you trying to bypass? When you close the throttle there is no air getting to the SC or engine so nothing to bypass?

[BB]

Two things.
1 is an idle valve. This you need when you have a complete air shut off system at the butterfly like an ABF engine.
The throttle closes and hits the idle switch which then opens the electronically controlled idle valve that takes air at a controlled amount straight from the intake snorkel before the air temp sensor, MAF and obviously the throttle body.
To do away with this system you have to close up all the intake holes where the idle valve was etc and make a stop that holds the butterfly open so as to allow enough air to idle.

2 is a blow off valve, which can only work if everything is before the throttle body so that the butterfly can close and block out the incoming boosted air and create a vacume in the manifold fast enough to allow a vacume valve in the intake system to be activated and vent that air out to the atmosphere WOOOSSSSHHHH.

Then I guess 3 which is a turbo wastegate which is a safety valve to stop too much boost even with the throttle wide open cause the air just can't take that much AIR man!
But that is not needed really on a SC car is it unless your maybe doing big high revs off throttle runs? But I think more of a idle switch SC bypass would be used.


I think what is happening is that you might be just getting too much boost from thee SC even at idle and you need to bypass the SC at idle?
My thoughts anyway

[Lee]

Small update

Solved my 4k idling problem--turned out to be 0 rings in the intercooler not seating properly creating air leaks--

Have driven the car a couple of times now-- but the blower seals blew and oil went everywhere.

So the blower is off  and about to get new bearings and seals.

The 3" exhaust is a very loud problem and have Andy helping with a couple of options to keep it below 95db for the cert.

Good things are the excellent clutch and gearbox--they were total unknowns. Gearing is 100k in 5th @ 2000rpm

The motor too is excellent --as well as it should be with 90k on it

Otherwise not much to report --it should be back on the road soon

[Lee]

Well the new bearings and seals went into the Sprintex and today I put it all back on the motor.

Started it up and it idles nicely--very pleasing indeed

Once I cure the loud exhaust  it will go for cert and then dyno tuning.

So not too far off being my daily again

This new engine, adapter plate, another  gearbox and the  Hydroboost braking has taken alot more time than I expected.

It's been 6 months in the oven

[GTI's]

Awesome!   Lets take it to the drags!   
I have some sticky rubber! 

[spooln]

The Wof guys will bug out when they see this.

[ritmo]

Such a cool project

[00quattro00]

I think it sounds perfect as it is now

[VW Imposter]

This is:
- one of the coolest things I've ever seen
- my favourite VW so far
- very impressive in concept and workmanship

it's a well reserved and humble axe wielding psychopath.

Well done, keep the pics and details coming. I hope there's a video install at some stage.

[Gordo]

How are things going now - been a while since last update?
Can't believe i hadn't seem this thread before despite being here for more'n 5 years - absolutely bonkers - but in a good way 

[Lee]

Hey guys

Haven't posted much lately but thought you might be interested in the next Polo V8 incarnation

The last supercharged implant was not a success as the blower blew up and the the drive shaft hit one of the external oil filter feeds and cracked the block.

After a lot of stuffing round I ended up deciding the BFM motor was no longer applicable.

I happened upon a later S4 4.2 40v chain drive engine from euroline which was just basically spare parts.

The engine was rebuilt using missing parts from Wolf auto parts in America----

So this new engine BBK is lighter and smaller than the BFM and fits the Polo engine bay with room to spare.

As it has variable cams I was not able to use the Link computer that has powered so many Polo incarnations

I decided to go mega squirt as the complete deal was half the price of the newer Links that were needed for the cams

So today it is all running and ready for a WOF after a long long rebuild

[mark2 golf]

Very cool lee. It should make more power too? How have you found the megasquirt?  Did you go with the pro?

[Lee]

The newer Link was too expensive when you add everything including final tuning compared to megasquirt $1300.00 for ECU -4 coils -crank angle wheel and sensor inc gst . Very easy to install even for a non electronics guy like me.

Been dealing with Jared from http://www.megasquirtnz.co.nz/ and he has been most helpful and very tolerent .

With the big bore exhaust and megasquirt I can expect the 360 horses that the stock engine produces maybe more.

I will take it to Jared in Tauranga for final dyno tuning in a week or two...

Will try to get some pics up

[rambo_005]

Sounds awesome Lee, look forward to hearing the results and seeing how the engine fits.