Sams Polo 3.0

[sambb]

Alright cool. All done on that front then. Thx

[sambb]

So in the ongoing E20 tuning of my car I've found a few things.

- The 98 RON petrol tune liked 0.82 lambda which was also described as on the safe side by the tuner. On E20 though it seems to prefer 0.80 sometimes tiping into 0.79's. eg It wouldn't handle 3.75 degrees of timing offset without up to 4.5 degrees of timing pull on lambda's matching the petrol tunes. But richening it up allows it to run that same advance with only a smidge of timing pull near 6000rpm.

- its not worth trying to squeeze that last bit of timing into it anyway even though 1.5-3 degrees of timing pull is considered acceptable if not a target in the dub tuning community. I don't really get why that is. If I look at a 3.0 degree added log and it has 18.5 degrees of timing in there in the upper rev range, but the 3.75 degree log did have that until it was instantly yanked back to only 15 degrees for nearly 800 rpm, then I dont see how the latter is better. Also this tune is what I'll be using on the track for lap after lap of abuse so coming back from that threshold to a log devoid of any timing pull I think is the wiser move.

- before I worked out that it wanted more fuel, it was pulling some timing around the torque/boost peak. It did this less so when I was running with the intake VVT activated. I thought that the VVT would enable better cylinder filling in this area and then as it was squeezed and banged that it would make for higher cylinder pressures than if there was no VVT. But the opposite has seemed to be the case. VVT 'on' between 2400 and 4250 seems less prone to torque peak knock - is that because the overlap it creates actually reduces the peak cylinder pressure?

- When I started out with this I'm pretty sure I was getting spark blowout. Short of LS2 coil converting it all I could do was shrink the plug gap from 28 thou to 24 thou. This worked instantly and the spark blowout that could be heard/felt is gone. But it could still be there. When it was happening it wasnt visible in the misfire detection logs which are notoriously inaccurate for anything other than idle misfires or literally dead coil pack diagnosis.
So the question is how can I look for spark blowout that might be too subtle to hear/feel? I assume spark blowout means no combustion takes place. The O2 sensor would see this as a sudden lean blip wouldnt it ie its only looking for oxygen content yeah, so a misfire will be seen as a whole lot of fresh air coming at it from 1 of the 4 cylinders right? Can spark blowout be seen in this way?
I'm reading that iridium/platinum plugs might be the go for ethanol fuels as they have a stable spark position making them more appropriate for blowout issues. On the flip side I always thought that they were higher resistance compared to copper and its all about peak current flow right which is why I've used BKR7E's and just changed them at every oil change... thoughts?

- oh and for the first time I've topped out the MAF on a few occasions. 194 g/s through a 2.5 inch stock MAF housing. Yes that was a cold dry night after a long cool cruise, but still its never gotten anywhere near that on a petrol tune with any K03 frame turbo before. Usually its hitting 185 g/s though, but thats kind of a moot point because this turbo is all about midrange anyway. So E20 blends work!

[Sydneykid]

Lots of questions Sam, hope I don't miss any.

I have seem lambda down to .75 work well, but that was on E25, so .79 on E20 isn't outrageous.

As per previous posts, I have never used a gap below 0.7 mm (28/1000), so my suggestion would be a coil upgrade if you need to further reduce the plug gap. You are going to need it eventually anyway.

In my experience more ethanol ALWAYS reduces knock, due to the cooling effect. There is a point where adding more no longer reduces the knock, which is where I stop.

You are correct, more cam overlap reduces the combustion pressure and hence the knock. But as usual you don't get something for nothing, there is a torque loss, but you do get a bit more exhaust turbine efficiency. So as usual it's a trade off, if it's in an rpm range where you need instant response then more cam overlap isn't a bad thing.

Spark blow out results in a sudden rich spike of unburnt fuel, ethanol does have an oxygen content so it's not as noticeably rich as with pump petrol.

I have always used copper spark plugs for ethanol, at the end of the day copper is better conductor of electricity than iridium and platinum, which are really there to prolong the intervals between plug changes. I have never had an engine run better on iridium or platinum spark plugs.

Topping out the MAF, now there is a good thing, more air = more power.

You know my thoughts on ethanol, best thing I ever did was to change when leaded Avgas became unobtainable from Bankstown airport and unleaded race fuel was $7 a litre (~$500 a race weekend in fuel alone). We used to mix our own E85 about 15 years ago, and then started buying it around 2008 when the United servos stocked it.


Cheers
Gary

[sambb]

Alright I might look at getting it out to E25 and do a bit more testing. I'll be buried in LS2 coil conversions now too.

Hmm surprised that a mis causes a lean condition at the O2 sensor. My thinking was that combustion consumes oxygen. If there's no combustion then oxygen levels in the virgin air remain high. I thought the sensor is not looking for unburnt fuel vapours, that it can't see them. No worries though, i'll take your word for it and now I know what to look for now so it'll be interseting to see if anything jumps out.
appreciate the help Gary

[GRP]

Where is Sam?

The only interesting ongoing thread on this forum and we have nearly 4 weeks of no posts.

Hope that all is well in Gladys land.

[h100vw]

I have a bit of news. The long awaited brake master cylinders have arrived from Germany. But given it's a bitch of a job to fit. Not sure it will be a quick fit to the car.

[sambb]

I'm still here. Like Gav said a possible solution to the overly long pedal has finally arrived. It will be a bitch of a job requiring a full flush/bleed with a system that is notoriously bad for trapped air in the ABS manifold. While I'm at it I'm going to do my rear beam bushes. The ones on the new car are two piece ones which aren't really seated correctly and look way to flexible when moved with a pinch bar. So I'll swap in my one piece solid bushes but that requires the rear brake lines being separated so that the rear beam can be dropped. Then while I'm at that, I may as well fit stainless braided rear brake lines. So yeah a master cyl job that needs a full flush, pressure bleed will drag into it a dropped and rebushed rear beam with new lines is quite a biggin and may be a while. Oh yeah and my master cylinder brace will then need to be remade because the master will sit further out. I'm not even sure it'll clear the channel that the fuel lines drop into. If the parts had arrived a few weeks back when the kids were still in home schooling and we were all stuck at home I would have gotten onto it but now it looks like things might open up and the kids are on hols right when the parts arrive which is a bugger.
Yeah things just went quiet car wise when the ability to get onto a track disappeared or visiting mates and workshops etc . Then youtube, netflix and beer became a problem for me ha ha. Then I ended up on the wrong end of a company vaccine mandate and was nearly stood down. At least I have my job unlike a lot of people which I'm thankful for, but running that line where I thought I was going to loose it wasn't fun.
Other than that I got back to some E20 blend tuning with UK Dave. I mucked around with plugs and now run some Brisk plugs. They are a silver (coated I assume) plug so slightly less resistance than copper maybe but have a really fine anode like an iridium/platinum. Tried them on a recommendation and despite the ethanol blend and way more timing I'm actually able to run a loose 29 thou gap which is bigger than the 28 thou I was running on peti. Better than the 24 thou I was down to to avoid misfires. Dave checked the dwell times on the stock coils and they were up there eg 2.8ms so there wasnt really anything to be had by pushing the coils harder. I didnt have the stomach to do a coil conversion so I'm glad that playing with plugs gave me a bit of a solution, but more testing needed. I'm glad Dave did offer to do a dedicated E20 tune for me. He was probably horrified that I had just previously upped the fuel pressure and added some global timing! It just keeps taking more and more timing now and is a bit leaner (0.83's) than I had it too. Same deal as before - no more peak power really due to turbo/cams, but the mid range is a proper step up from petrol.
more to come, I've just been a bit preoccupied

[sambb]

who wants to here a mildly decent sounding NA 3.9L cosworth V12 @ 12,000 rpm
T.50 VLOG | EPISODE #12 | DARIO DRIVES GEORGE FOR THE FIRST TIME - YouTube

[sambb]

engine rebuild time!

I'd toyed with the idea of doing the bottom end myself for so long but having to get all the measuring & fitting tools needed plus knowing that finding the uninterrupted time required would be nigh on impossible, I decided to out source it. It was picked up yesterday and is now down at M.I A engine services with all the bits to get the bottom end built.

The parts will include:

- S3 BAM pistons, very good condition second hand cleaned up and sent down to Special piston services in VIC for skirt recoating and additional crown coating.

- supplied with ring set from SPS

- Forged China rods which are a knock off design of Bar-Tek X- beams. 20mm wrist pin to match the S3 pistons, force pin oiled


- ARP 2000 rod bolts

- OEM main bolts, main bearings and rod bearings

The hope being, that as its only a 90,000km block that did half its life standard and half with a stage 1 tune with good service history and an OTT one from me, that its all square and true. Hopefully it wont need line boring and can be within tolerances with just a skim and a proper re-hone.
I'll then do all the ancillaries, front/rear main seals, fit the brand new AGU Large port head (probably with VVT from one of my other engines) , the custom (by me) baffled sump which is getting welded up now too and swap all the mechanically adjusted cam timing gear across from the old engine (IE idler, 1.8L 16V KR tensioner roller and Cat Cams adjustable cam pulley).

I'm agonising over a couple of things:

- I'd have liked to go with ACL rod and main bearings but $$. If there are any issues with the supplied OE ones then we'll probably go that way where needed.

- I'm really not sure what to do re exhaust valves. The standard thing you'll hear is that you should change out the stock sodium filled exhaust valves for Supertechs. Where I struggle with that is not knowing whether the failures of the stock valves are rev related or heat related. If they are rev related then any of the turbo options and the stock cams I'm running will not rev higher than the stock redline anyway. If its a valve float issue then I don't see how adding an even heavier stainless supertech valve with a stock spring is going to be better controlled and I definitely dont have the bucks to do valves/spring/retainers or to extend to the lighter inconels. If it's a heat issue, then I do hope that sensibly tuning the right size turbo and running an ethanol blend will keep the combustion temps/EGT's in order. Also the exhaust valves I have are brand new in a head thats still in the wrapper so I'm starting with something that hasn't been pre-flogged. Still though....I'm not sure.

- Gates racing cam belt or not? Again revs are going to be stock redline, with stock turbo cams so I don't know if a belt thats 3 times the price is warranted for an engine in that guise.

- head gasket....at the moment I have a stock one with stock head bolts but again at no more than 280-300 hp do I really need more?

- turbo choice..... a plug n play Littco K280 (reworked innards in the K03 frame) is attractive just due to the convenience factor but I'm pretty sure I dont want to stay with factory manifold leaks, constant turbo-manifold gasket blow outs and leaks and the high EGT's such a small frame turbo gives.
Most likely I will go down the path of running my Golf Mk6 Gti EA888 gen 1 IHI that has nice open long runners split 1&4/2&3 (still single scroll though) with what I'm hoping will be a far more reliable and easy to work on turbo-engine connection. This is my mock up on my other engine.


anyway, stay tuned. More picks to come.
sam

[Sydneykid]

What are the inlet and exhaust valve sizes Sam? I'm not sure on VW's but a lot of manufactures of turbo engines have adopted the philosophy of going "small" on the exhaust vales for emission control reasons. The rule of thumb used to be to have the exhaust valves 80% of the diameter of the inlet valves. I have seen recent turbo engine that are in the high 60's. The advantage of a larger (more appropriately sized) exhaust valve is more power with the same boost or the same power with less boost. Either is a winner in the inlet air temp stakes. If the exhaust valves sizing is in the ballpark then I would stick with OE's.

On Nissan RB's a 1.5mm larger diameter exhaust valve facilitates the same power at 3 to 5 psi lower boost, so it is quite noticeable.


Head, OE studs or bolts? If bolts I like to change to ARP studs, cheap insurance.

I'd suggesting checking the weight on the exhaust valves, often sodium filled valves have less wasting that full stainless and hence the weight difference isn't as much as we might think.

I'd stick with the VW cam belt, ditto bearings.

Personally I like to assemble my own engines, I do get the measurements done externally, bearing sizes, crank straight, main bearings aligned, deck flat, hone, bore and piston clearances. I also get the cam bearings alignment checked and all of the moving bits balanced. Then I do the assembly myself. I don't do enough engine assembly to get bored and the satisfaction when it runs is second to none.


I have a shipment coming from the US in the next couple of weeks, if you need anything from ARP etc I can get it thrown in the box.


Cheers
Gary