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Old 15-05-2015, 07:49 PM   #1
iain ambrose
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Default Project performance WBX build

I'm going to mirror this thread as I'm finding myself spending more time on VZI these days....

Though I would share my new engine build currently in progress.
Sadly the current engine has been having some issues of late with a noisy valve train.
I changed the hydro lifters with no improvement and having measured lift across the valves it appears one lobe is going flat
Fortunately I have been planning another build as a spare.

I already had a 2.1 MV short block purchased for 75.
It was sold as seized and this turned out to be pistons stuck in the bores.
After a strip down and clean up I checked over all the parts.



The cam was worn on the lobes so that was binned.
All the pistons cleaned up nice but will also be binned as they are the low compression MV type.
The crank looked fine but just needed a polish.

All the parts where dropped off with Jim @ the engine shop for a good check over and crank polish.
He also has a second hand set of DJ High compression pistons kicking around.
2 of the original liners where toast where they had seized so only the other two where honed.
Jim now sells uk made replacement camshafts ranging from stock to several performance versions.
The existing cam i'm running was sourced in the USA and is a CB Performance unit.
It's spec was:

Duration 270 degrees
Lift @ cam .298

I decided on Jim's fast road cam with the following spec:

Duration 290 degrees
Lift @ cam .289


Looks like a nice cam and I will confirm this later.
Anyone who builds these engines will tell you how the cost's escalate compared to a type 1 engine.
Head gasket kit 120

A set of piston rings 55 (twice the price of a T1)

Main bearings and big ends come in at 65.

That said Jim only sells the top quality parts.

A quick comparison between the MV and DJ pistons.


You can see where all the extra compression is made in the dishes.
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Old 15-05-2015, 07:49 PM   #2
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Currently I am missing many engine parts and although I could swop them over from the current engine I would rather build this engine as a completely separate unit.
The only parts coming over from the existing build are the heads and valve train as i've already invested time in porting them plus they retail at over 300 a piece.
The main missing parts that I need are:

Flywheel.
Clutch assembly.
Pulley wheel.
Oil Pump.

Currently I run a stock 1.9 setup for the flywheel and clutch.
This is a 215mm unit and has worked well, but it's only really designed to handle 80hp rather than the 120hp currently running through it.
The stock 2.1 setup is 228mm and won't fit a T1 gearbox without some serious grinding work.
Getting good stock flywheels is tough these days so you can now buy new units made in China that are QA'd in the states via AA Performance.
In addition to stock sizes there are some 200mm units and also lightened units.
Personally i'm dubious of anything made outside of a vw factory and after some research the horror stories start to emerge regarding these flywheels.
Some have bolted them up only to find they don't fit perfectly central making them an expensive paperweight.
As I understand AA Performance have now solved this but working for a company that imports from China I know they will take every opportunity to cut corners.
I just don't want the hassle and worry about this.

Lucky for me I found the holy grail of vw t25 flywheels - a type 4 200mm NOS unit.

Also purchased was a matching 200mm stage 2 Kennedy pressure plate and a needle bearing for the center.



This units are factory balanced but I plan to have this plus the flywheel, crank and pulley wheel properly balanced.

To run a wbx engine with a type 1 gearbox you have to solve a minor issue with the shaft support.
On a type1 engine you have a central gland nut fitted with a needle bearing inside.
On a type 25 engine you have a longer gearbox central shaft that sits nicely inside the crank which has a needle bearing.
To get round this issue you need to fit a needle bearing inside the flywheel.


A couple of washers with a bolt presses it in nicely.


Next is to start checking components before the build.
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Old 15-05-2015, 07:50 PM   #3
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With the last engine i'm ashamed to say that I simply fitted the camshaft without checking it properly.
It's certain to say that a camshaft should not have flat lobes after 30k especially as i'm a bit OCD with servicing.
This time I plan to check and confirm all the parts used and also blue print where possible to hopefully produce a quality engine build.
I started with the camshaft and bearings.

First thing to check is the cam thrust bearing.



Looking at the manual it states up to 6 thou gap is acceptable but I want to be looking at around 1 thou.
Straight away we have a issue
I looks like the bearing splays when fitted into the case as it runs nicely on it's own in the camshaft.
A quick flat sand on the thrust side should help.


Nope, it's gone from no clearance straight to 6 thou
Looking at the thrust surface it's uneven where I have sanded so it's in the bin.
These are mahle units so not impressed.
T25 engines run a single thrust stock but i've decided to order a set of double thrust and see how they fit.

Next, check the cam lift:


The two exhausts come in at 267 and 269. (1 % variance).
The two inlets are both 283.
https://i.imgur.com/smqSTj9.jpg[/IMG]
One inlet has a slight +- 1 thou variance on the lobe bottom, the others all look fine.
The potential issue with having an uneven lobe bottom is that it affects the hydro lifter as it maintains a zero gap.
As the valve returns to the closed position any variance in the cam lobe bottom will result in unwanted lift.
I believe this is one of the issues with my current cam as a rolling road test indicated a valve not fully seating.

I'll be checking that lobe again.
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Old 15-05-2015, 07:51 PM   #4
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Next is the oil pump.

The stock T25 engine runs a 26mm pump comparable to a late style type 1 unit.
As with a type 1 when running an aftermarket cam and wheel you have to use an early style pump to allow clearance for the wheel bolts.
If you research vw oil pumps it highlights some interesting issues with the aftermarket pumps.

Firstly is the fit in the case.
An original pump will have a tight fit inside the case, aftermarket pumps all have a noticeable loose fit which is not a good thing.
The more the oil thins under operation the more is able to squeeze around the pump body rather than around your engine meaning right when you need the oil pressure the most it's dropping.
A solution to this is to cut an o-ring groove into the pump body to prevent leakage and it's something i'm still considering.

Also, aftermarket pumps come with an aluminum cover rather than a steel one.
A steel cover reduces pump gear wear and the subsequent pressure loss.

I made a 50% improvement in oil pressure on my existing engine by swapping to a steel cover and blue printing it.
The same process has been done for this build.


I used a shadek 30mm HD oil pump as it's a good quality start point.
The original pump cover was cleaned up and then using a flat surface progressively sanded through various grades until a mirror finish.
The shakek body with gears undergoes a similar process to ensure it's perfectly flat.
Next I opened up the oil outlet to be the same diameter as the case.
It might be that a type 1 case is smaller to match this pump but I want an smooth uninterrupted flow.
Found the right size drill bit.

After a clean up with a dremel.

Some suggest to radius the outlet hole inside the pump but for this application it's not really required.
All ready to install.


So, that's everything up to date.

Next jobs are getting the case properly cleaned and also paint it having already spent hours prepping it.
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Old 15-05-2015, 07:51 PM   #5
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So, did a bit more research regarding cams.
Lucky for me there are some real engine builders who share knowledge
It's hard to believe we where able to live pre internet lol.

Anyways the general consensus is that the bottom of the lobes MUST me exactly round with +- 1 thou being the upper limit.
Running solid lifters is not so much a problem but more an issue of excess noise from the extra clearance on the lobe.
I thought it best to go back and double check the readings as 1 thou is a very small reading to check accurately.
It looks like there must have been some play in the gauge mount as the bottoms now look perfectly round.
Well i'm happy to say this cam looks great but I just need to check for any run out on the cam wheel.

Yesterday I secured access to a donor engine for parts which should provide most of what I need.
Hopefully a couple of liners will be good also.

Once I have the pulley wheel I need to find someone to balance it.

First choice was John Mayer up in the Scottish Isles but I suspect the courier costs would be more than the actual machine work.
I've spoken to James Calvert a number of times and he also seems a good choice, so i'll give him a call.

One other thing that's bothering me are the conrods.
They all cleaned up nice but as a known weakness in wbx engines I need to consider options.
The stock units run two types of bolt (stretch and non stretch).
Early engines appear to use the same bolt as the t1, but the later engines went over to stretch.
On my current build I reused a set of early non stretch as the manual states the stretch ones should always be replaced.
It's common practice to reuse the stretch bolts when rebuilding but leaving out the final 90 degree 'stretch' turn stated in the manual.
I think this would be fine for a stock engine but I would like to feel comfortable seeing the rev counter hit 6k on occasion.
You can get new stretch bolts but at close to 100 for a set you are already quickly moving into the aftermarket price range.

A t25 crank shares the same big end spec as a t1 (hence it's use in T1 engines) although the main bearing layout differs.
Sadly the small ends are a larger diameter on t25's though.
This does mean you can run t1 conrods giving you a good selection of options if you are prepared to machine the small ends accordingly.

James Calvert told me he sells conrods to any spec so i'll be speaking to him for some options I think.
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Old 15-05-2015, 07:52 PM   #6
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Today the replacement camshaft bearings arrived.
They are Silverline made in Mexico and I have heard some good things about them.


Side by side with the Meyle one (Left).

You can see where some sanding has highlighted the low spot on the outer edge.
You will also note the lack of a locating tab on the Meyle unit.

The width comes in dead on 28mm so once the case is back from cleaning i'll trial fit.
Also purchased 5 genuine flywheel bolts as these are allen heads.
I've used standard bolt heads previously and there are all sorts of clearance issues that I could do without.


I'll be ordering a decent set of scales tomorrow as I need to check the piston weights.
Not looking forward to taking weight off pistons should it be necessary.
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Old 15-05-2015, 07:53 PM   #7
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Yesterday I phoned James @ Stateside for a little chat about by build options.
Perhaps it would have been wiser to start with this phone call
As with many things on the internet (bloke down the pub) you can't always take things on face value, so it was good to talk to someone who clearly knows his stuff.

It seems the oem flywheel I have is actually cast not forged and a little tapping with a spanner confirms this.
This is not really a huge problem but it does mean lightening is not a option.
He does a forged lightened flywheel for 190 so I plan to return the oem flywheel in favor of a forged unit.

I was hoping with this engine to have a wider rev range up to around 6k.
James can supply a set of recon vw units, balanced with new little ends and new bolts.
Uprated bolts on stock rods are limited and not really in my price range for what I want.
Alternatively he does a full set of H beams, again balanced and with arp bolts.
Cost wise i'm looking at 145 for the refurbs or 360 for the H beams.
It would be nice to uprate to the H beams but in reality this engine will be in a street car with no clutch dumping or sustained high revs.

He also offers a 4 dowel option on the flywheel/crank as extra insurance against unexpected detachment but again it's not really going to be necessary IMO.

So, one flywheel, set of refurbed rods and a dynamic balance seems to be the correct choice.

Got the engine case back from a chemical clean but it still has varnish in places that won't come off.
This weekend I'll be checking over the new cam bearings and hoping for a better result than last time
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Old 15-05-2015, 07:54 PM   #8
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Last night I sorted out the cam thrusts.
Because I decided to use twin thrust bearings there was the issue of the locating tang on the second one.
The case only has a tang on one side so either you file off the tang on the bearing or cut a new locating groove in the case.
I chose the later as it seemed a better idea.
Out with a file and after some careful work the bearing fits nice and snug.

Once again the thrust bearings where splaying out so more sanding was required.
Finally I managed to get the end float to just over 1 thou, which will do fine.

The cam bolts have been slightly filed down to give a touch more clearance and I need to check again with the pump body in place and the bolts are torqued up.
Further to this I want to close the case and make sure both the cam end float is the same and also that the bearings don't distort.
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Old 15-05-2015, 07:54 PM   #9
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Been busy today checking over things.

Firstly I found a bunch of photo's from the clean up so I thought I would post first.

Engine as picked up.

One of the best cranks vw made imo, good for 400hp (4 times it's original application ).

Showing where it needed polishing, probably from sitting for so long outdoors.


I bought gallons of vinegar for the clean up process, the place smelt like a chip shop for days.


Does a great job of removing all the rust and grime.


Had to soak the oil pickup in thinners as the glazing was terrible after years of burning oil passing through it!
From

To
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Old 15-05-2015, 07:55 PM   #10
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To check the cam end float the wheel was first bolted up.
Various torque settings are suggested ranging from 14 - 25 pound foot
I went with 18 as suggested by an engine builder on shoptalk called 'tencentlife' who I know is particularly knowledgeable on all things wbx.
Lock Tight was added for extra peace of mind.

Before closing up the case a quick check to see if there are any pump clearance issues.
First problem is the studs are too short being set for a 24mm pump, so they where removed, cleaned, lock tightened and left with more thread.

With that done everything was bolted up and is all good.
Took the pump body out and closed the case with four of the main nuts to check the endfloat.
Happy to say it's just over 1 thou and the cam spins nicely with no issues.
With the case apart again I've checked the main bearings fit the case saddles and that the oil feeds line up nicely.
Gotta love wbx engines, still stock size main bearings after probably 100k dragging a van around
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