The '2 ton bugswatter' - back for a gentle stroke

[JP]

@ Tommy200rs,
balancing knowledge and balance factors is something that has been passed down to me through other engineers through the years. What you'll find is that most engineers share information with each other in order to further their own knowledge and progress by the sharing of ideas and theories.

There is a few engineers handbooks that carry most old school popular balance factor configurations. For 90degree v's and narrow v's. once in a while you come across one that has not been published for whatever reason at which point you need to reverse engineer the process.

In such a situation you would first find the average small end and big end weights of the rod piston assembly. After which you start with the most common balance factor of 50%. You make up these bobweights and spin up the stock crank assembly. If it is not in balance you make up a 40% balance factor bobweight and spin up the assembly if it has gotten worse you try 60% etc... By process of elimination you can then usually determine the end figures.

As for manufacturers tolerances I've seen piston rod assemblies out of balance by as much as 20gramms at the small end on an externally balanced engine. Whereas internally balanced engines tend to be within 5-6 gramms at the small end. All comes down to what time of the day the components where made and balanced and whether the operator is having a bad day or not. An out of balance engine will still run just not smoothly and is more susceptible to heavier wear and tear resulting in a shorter serviceable life.

As for the specification of a balanced race setup each engineer has their personal preferences on that front. The ones that have modern digital technology to assist them tend to have much bigger tolerances as the machines that are used are the same that OEM manufacturers use. Where as those using old school dynamic balancers tend to be more particular and work to within 1gramm and where possible 0.5gram.

Then the argument starts about oil deposits on the rotating assembly changing all the weights as the minute you add oil to the bottom of your piston one may be a couple of grams heavier compared to the rest so was it really worth balancing to within 1 gram?

On an I5 if it is perfectly balanced you should be able to do the Bentley trick which is take a 20p coin and place it on it's edge on the rocker cover of the engine whilst running. It should then stay perfectly balanced on it's side as you rev the engine smoothly through the lower rev range.

[JP]

Another picture update of the cars build up.

Being my daily hack with no alternate mode of transport without unnecessary financial outlay the aim was to do the engine swap over a weekend at a friends garage who had a nice 4 poster for convenience.



So having started saturday morning at around 10am we got stuck in and stripped the engine out the car. Leaving as much as possible connected for ease on the re assembly.




By the end of the day we had the new engine fitted up with all the ancillary brackets of the old engine ready to be dropped in for Sunday morning.




An 11 O'clock start and by 4pm we had the front end back together ready for all the fluids to be added and a nice new radiator.




Now the old radiator had distorted and split the core from what we originally thought to be a blown headgasket.



Well yes something had let go but not the headgasket. Inspecting the hotside of the turbo the inlet of the hotside was clear to be greeted with and abundance of burnt coolant on the hotside outlet. We had infact managed to split the core of the turbo causing hot turbo gases to enter the coolant system resulting in the tremendous pressure to blow the radiator.



This left me in an awkward situation on a sunday afternoon as the car needed to be back on the road for the school run on monday morning. So the decision was made to over ride the after run coolant system with a toggle switch to stop the water system pressurising too much on shut down and build the car up with the knackered turbo until a new one would arrive. This unfortunately meant that rather embarrassingly every time I started the car up there was a tremendous amount of coolant smoke coming out of the exhaust despite the lovely fresh engine in there. Oh well can't win them all.




A couple of weeks later Doug at MRC provided me with the complete K26/30R hybrid kit from 034. The choice was made by myself to use a .63 backhousing to keep the midrange driveable for the street at the potential sacrifice of some power at the top end of the rev range.




From experience knowing that the collector is a restriction on the stock exhaust mani from the S6 I had at an earlier date in the cars life modified the collector to reduce some backpressure. Wanting to see how effective this was on the larger turbo I decided for the moment to see what could be achieved with this mod on the stock manifold.




A gratuitous shot to show that we have just enough clearance




Having fitted the larger turbo to the car it was obviously in desperate need of a remap which due to the unfortunate timing of it's urgent requirement could not be done live as Mihnea was not in town. However he very kindly came to the rescue with a nice baseline map created using my Zeitronix data logs.

With the AudiSRS North/South Dyno day the next morning at Surrey Rolling Roads (for the South one) I decided to go along with my friends and put the car on the dyno just to see what she did at a temporary 1bar of boost and the ignition timing knocked out of it for safety until the live map.







Looking at the results I could see the exhaust mani was going to end up being a top end restriction so some further plans were in the pipeline prior to the live mapping session.

[Error404]

good result on the stock ex mani none the less - did you just knife edge the divides in the collctor and match the ports to the head then?

[GazzaG60]

what EGT was it pushing?

[merlin's S4]

Great thread!

Is the standard intercooler up to the job?

[JP]

good result on the stock ex mani none the less - did you just knife edge the divides in the collctor and match the ports to the head then?

Matched the runners to the gasket to ensure no steps creating hot spots at the entrance to the EM. And the dividers were cut back and rounded rather than out and out knife edged.
I tend to try and avoid putting any knife edges in EM's as they create hotspots that will encourage cracking.

[JP]

what EGT was it pushing?

On the dyno it saw 840-850 Celsius, on the road accelerating in 4th 5th 6th 820-830 Celsius. Quarter mile type launch and redlining through the gears till top of 5th 850-860's. Measured 1.5" back from the cylinderhead in runner number 5.

[JP]

Great thread!

Is the standard intercooler up to the job?

Cheers, forgot about the intercooler setup, will have to take some pictures of it later on when the bumper is next of as I played about a bit with various configurations.

For this particular dyno run my setup was as follows

Stock airbox and MAF setup with 034 hose as pictured earlier into the turbo using stock breathing system.

£65 incl p+p ebay universal bar and plate intercooler. 60mm inlet and outlet, 450 x 300 x 75mm core.

Boost hoses, utilised the stock k24 outlet trimmed to fit the gt30 and trimmed it down to mate with SFS 60mm couplers and boost hoses. Ran a 90 and 135 to the intercooler then a 45 and 90 out of the intercooler to mate up with the original factory boost hose that normally couples to the stock intercooler exit.

I'm no longer running this hose setup but I'll get to that a little later on in the thread, my ultimate aim was to attempt to make it look as stock as possible outside the car and under the bonnet.

[Error404]

Matched the runners to the gasket to ensure no steps creating hot spots at the entrance to the EM. And the dividers were cut back and rounded rather than out and out knife edged.
I tend to try and avoid putting any knife edges in EM's as they create hotspots that will encourage cracking.

good info thanks
I'm doing a mild porting job on my head and manifolds at the moment and hoping to squeeze the most out of the k24 set-up. Cheers

[JP]

Before the swap mine made just under 290 on stock intercooler setup with a mild ported head and that exhaust configuration at 20psi tailing of to 11psi at redline. The poor little thing was screaming it's nuts of on overspool trying to supply enough air and may very well have been it's final downfall.
So keep that in mind when pushing it as the compressor physically can't flow enough to make big top end gains you will see most of it in the midrange and driveability.

[Error404]

Thanks for the warning - really looking to maximise the efficiency of the stock set-up and using Paul's homefries chip, midrange driveability and response over top end power for me although 301bhp has a nice ring to it on the K24 - as you say how long it lasts is a different matter

Anyhoo sorry for the interception, back to your project

[GazzaG60]

not too bad on the EGT then for the manifold there. good work...again.

had much experience with the I5 before or just motors in general

dont tell me this is your first build. lol

ive not seen over 730c so far just after the turbo so thats maybe 800 or so.

[GazzaG60]

if you want a k24 to do 300+ id look to porting the hotside.

[JP]

Been a bit busy so haven't had a load of time on my hands to continue with the thread so we are a little out of time sequence but anyway here we go.

Shortly after the Rolling Road day we went to turn the Boost up to 1.4bar on the car after which it started missfiring and smoking on startup and idle pretty much after the first couple of passes. With the final crunch being an abundance of smoke coming out of my bonnet smelling of burning oil.

So I eased of and cruised home to investigate. Well the missfiring was from the spark leads that had arc'd on no.3 and 5. Went to investigate the cause and found that both spark plugs had separated from their bases and you could spin them freely whilst holding the nut.

They didn't look lean infact if anything a tad on the rich side, so scratch head time. Further investigation found that my oil levels were a tad low to the extend of 1ltr in less than a 100miles

So I started to strip her down to find the following two issues, an abundance of oil dripping out of the compressor housing on the turbo



and an intercooler filled with oil



Feeling the shaft of the turbo it was wobbling like a good un, less than a 1000miles on the clock with 98% of it at 1bar and it was time to take the turbo of already

Well the only conclusion that could be drawn from this was that the octane rating of the fuel was lowered so far by the oil content in the intake that it made it difficult for the spark plugs to fire causing the above failure? As it had never happened to me before or anyone I know it is unfortunately the only conclusion we could draw.

So it was send to a UK authorised Garrett agent (Owen Developments) under instruction of the US supplier for inspection, a warranty report and rebuild. Long and short of it they found two issues with the turbo, something to do with the exhaust heatshield being for an internal wastegate turbo rather than an external gated one resulting in it rubbing on the back of the blades on the hotside and the Oil seals on the compressor housing had failed.

Frustrated but stranded with no car as it is my Daily I just told them to fix it pay for it out of my own pocket and worry about dealing with the US supplier at a later date. Being informed it was going to take two weeks I managed to borrow a car at which point I figured I may aswell sort the engine bay out and get the Wagner exhaust mani on there at the same time.

Now being the type of person I am I couldn't help myself but clean up the casting on the exhaust mani and plasma coat it with zirconian, whilst awaiting the turbo.



I also received my new wetblast cabinet and figured I may aswell clean some of the engine brackets up and ancillaries.





Shortly after which the turbo arrived back from repairs. Looking at the hotside and the Wagner exhaust mani I realised there was further improvements to be had.

So I took the .63 hotside



and ported her



Which meant the exhaust manifold could be once again further improved upon. So I milled out the turbo flange and blended it to the hotside to minimize turbulence into the turbo





In order for this to work I made a conscious decision not to run a exhaust manifold to turbo gasket and instead milled both surfaces 100% true to ensure a perfect seal that way.

Whilst at Owen Developments I also got them to modify the compressor housing to reduce the effect of the anti surge housing.



Under recommendation from Owen Developments I got rid of the stock airbox setup and the silicone elbow in favour of a mushroom filter. As they where of the strongest opinion that the amount of air that the turbo needed to sustain higher boost could not be sucked through the stock air intake system. which in turn was their opinion as to why the oil seals failed as the oil was literally being sucked into the compressor housing past the seals as I came onto boost.



Some gratuitous shots of the cleaned engine





Now note the relocated MAF in the above picture on the bottom right. I quickly discovered that there is no physical way you can clamp the MAF tight enough to stop boost hoses popping of without totally distorting it and endering it useless.

So under kind advice of Doug at MRC he recommended that I strap her in between some metal pipework to stop the hoses blowing of.

So to ensure the car was running again by the morning I had to improvise and use what I had laying about. So I mocked up an aluminium elbow for the TB side.



And then proceeded to modify the SFS billet connectors to end up with this contraption.





The end result meaning the hoses where no longer trying to separate. All they had to do now was seal against expanding pressure, meaning lower clamping forces are required and the MAF housing doesn't distort.

Happy that everything was running as it should be I took advantage of the fact Mihnea was readily available to put a live map on the car for me. She was mapped up for approx 1.7bar as the stock ECU had issues with giving consistent boost curves across the gears for anything higher. So map was left as a nice safe one to allow me to go out and get a boost controller to play with.

So I'll end this post with a power plot of how the car stood on stock ecu fuel and boost management.

[knobstar]

Impressive stuff as always That compressor intake looks like it could swallow a ruddy planet!!