Prawn and BigAls A3 Track Car

Yea, me too!


I’ve got 27 images to upload, 2 videos, and a load to write about each of them!

I could bang a few pics up and a quick summary, but that seems a waste.

It went well. Much fun was had. I really hope to find the time to write it all up this evening. I’ve literally not stopped this week. Early starts and late finishes every day

Today is a sad day folks:

http://www.audi-sport.net/xf/threads/gops-subtle-mod-thread.154987/page-14#post-2914613

RIP to the legendary ASN hand-me-down S3! from a lowly 210bhp to an insane 604bhp over it's 16 year life. Hopefully @Gops will still stick around though, he's part of the furniture!

As for the A3, I've not even had time to drive it since the drive home from B5! Things are just SO busy at the moment, I can't even think straight.

I now have just this evening to do all the remaining work on the A3 ready for Bedford on Friday.

List of tasks:

Bleed brakes all round.
Check tracking and adjust if needed (Hoping it's still fine - should be)
Re-make 1 splitter mount, I stupidly left them on when i went to Bills, and ripped one off on a pot hole leaving Bills entrance!
Refit splitter
Make covering shrouds to focus more air into the brake ducts
Set up maps 1-3. The map on the car is finished, and needs to be loaded into slot 3, but I need to load up a 0% duty map for low boost, and a slightly more progressive map in slot 2 should it end up being a really cold / damp day. This may well end up being a thursday night job on the way up!

Somehow find time tomorrow to fit brake ducts when they arrive from ASH. First parcel went missing, so I've had them sent on a 24hr to arrive tomorrow. most annoying, as I'll only have an hour tomorrow to get the ducts done, and get everything packed, then I've got an NCT class from 7-9:30, so won't be leaving for Bedford until LATE!

I'll post a few bits about Bedford over the next few days, but I'll save a proper write up until after I've finished the Badger5 dyno write up first, as I want to keep things in order!

Once Bedford is done, I'm going to attempt to have a rest in the 7 weeks I'll have remaining until BabyPrawn is due!

No rest for the wicked it seems....

How does 6000bhp sound Big Bad?

Get your cheque book out

I'm too poor

I'll give you £200 and a twin for it

0130, I'm here!



And I definitely deserve this:

Depends who's asking

Awesome day!

Write up to follow, probably on Sunday

I know I know I know!

I'm working on it!

So, it's about time I got round to writing this, and it sounds like it'll get PT off my case, so here we go

Since getting the car running, I'd been pretty keen on doing most of the mapping myself.

This started out pretty well. The old map wasn't a million miles off, and the car was safe to drive from the off.

I'd started on 0% duty, and worked my way up slowly to around 22psi. The problem was, with the awful weather we've been having, and my options for road tyres limited to some fairly slick and very old A048's, I was having REAL difficulty in getting a clean and solid pull through the gears without wheelspin.

This meant I couldn't get a decent trace to fine tune the fuelling and such things. I KNEW it was rich, but with every pull interupted by wheelspin at different points, mapping to full power was proving impossible.

With Bedford booked, and time fast disappearing, I gave Bill a ring, and he was able to book me in at fairly short notice for some dyno time on the Sunday.

There was no 'plan' as such. Just to run the car on the dyno, see what was what, and go from there!

So, I arrived at 1030, armed with Bacon rolls for Bill and Tuffty, and we strapped the car down to the rollers. Not before much faffing around removing splitter mounts that I'd forgotten had to go!



I'd only set up 2 maps to try intially, one at 0% duty to get a baseline, and one with my progressive boost profile, but an unfinished fuel map due to the weather conditions we'd been having.

So, strapped down, boost lines plugged in, 02 sensor in the exhaust, it was time to run!





0% duty across the range, so actuator pressure. Around 14-15 psi:




279 bhp. Not a bad start. Not massive, but not at all terrible. Fuelling was dipping to low 11's, and boost running around 15psi as expexted.

Time to turn on the N75. This was the bit I was nervous about.

I knew it had been 370bhp before, and I knew it FELT really good on the road, but after 9 months without driving the car, was I going to notice 20/30/40bhp lost? Especially when I potentially had more torque also? I just didn't know.



It turns out, time really does numb the brain!

333bhp. No timing changes, so still fairly conservative, and fuelling going REALLY rich at the top end. This was the region I knew needed work, but due to traction issues I hadn't been able to reliable get a data log to allow me to improve it.

Straight after that run, I'll be honest, my heart sank. It felt so quick on the road, and I'd been so happy to get it back. I was hopeful of a fairly decent result straight off, but clearly, I was a little too optimistic.

However, we then did an overlay of the old setup, vs the new setup, and suddenly, things wern't looking all that bad.



The old map is shown here in red. The blue line is the map as I arrived in the morning.

It's pretty much matching the old engine exactly up to 6k, only falling short of the mark beyond 6k where the old engine really sang. No wonder it felt just as quick on the road.

It was also matching that power and torque up to 6k, from a fair bit less boost, showing that the small port engine really does seem to be more efficient. Above 6k, my new profile was higher than the old setup, but it was also a LOT richer, and torque was dropping off fast, hence the 37bhp difference at the very top end.

It was clear that it wasn't running as well as it could be, so Bill hooked up the laptop, read the maps, and started making a few tweaks. I took a few random photos!





Clearly I'm no Tuffty when it comes to photos

A few more runs, and a few more tweaks, and whilst there were no huge changes in peak figures, things did start to look a lot better. the shape of the torque profile was improving, and run after run power stayed very similar, but the shape of the graph changed as Bill tweaked.

Bill lifted the boost to closely match the old profile, and also leaned out the fuelling so it was at a similar level to before.



A comparison run then showed that for nearly the same boost and fuelling, the small port setup was making more of everything, and sooner, all before 6k. It was only after 6k that torque would fall off fast, and the peak figures would end up being lower than before. Everywhere below 6k, it was considerably more efficient for exactly the same boost / fuel.


This seemed like a pretty good time to put the kettle on, so we enjoyed what must have been the 4th cup of tea, and chatted about what we'd change next.

Up until this point, no timing changes had been made at all. I also noticed it didn't appear to have been using much / any meth at all. Given the issues that so many have had with meth systems in the past, I decided it was best to check it before continuing:



Yup. working fine. It just uses very little on the small nozzle, and I'd rather keep it that way. When we were using the medium AEM nozzle I was getting through 25L of WMI mix in a single trackday, and it got pretty tiresome!

We drank tea, put the world to rights, looked at the vast wealth of toys on show at B5 (dreaming of one day having a gt3076!), and Nathan popped in to say hello in his 20vt mk3 on DTA.

Once we were suitably tea'd, we fired the car and the dyno fans up again, and gave it a cold run to get another baseline before further tweaks.



OH! there's a surprise. A cold run after lunch immediately netted another 10bhp for no changes. Just goes to show how much heat does change things. Inlet, coolant, and EGT temps had remained really low during all the mornings runs, but clearly as heat built up as a whole, it lowered the power figure, only by a whopping 2-3%, but it's still a measurable figure.

Seeing as we'd not seen a flicker from the knock light all day, Bill added 2 degees of timing, and we ran again:



Still for those not watching the video:



Not bad at all. Given the fairly poor start, I was certainly happy to see a 35x run! Given the torque increases elsewhere, things wern't looking too bad at all at this point

The Noise you can hear is the yoko A048's screaming, they were louder than the engine in there!



We decided to look at some of the runs, and compare the torque plots.



Blue here is the old engine. Red is what I arrived with, and the orange is the torque I have after lifting boost and fuelling to match the old engine. You can see that for the same boost and fuel there is more happening, sooner, and with some added timing, it remains more until around 6400rpm now.

We played around with ramping timing back in after peak torque, and added another 2 degrees after 6k. As we'd found before lunch, peak power didn't rise (most likely due to things heating up further), but the way it held onto torque improved, and it was only right out at 7k that the two curves differed considerably:




We decided that now seemed like a good time to stop tweaking. We could likely go on for days trying to get it absolutely perfect beyond belief, but past experience showed that I'd likely end up tweaking and fine tuning the delivery on the road anyway, so trying to squeeze the last 2bhp on the dyno was a pointless exercise.

Here is the final plot, red being as I arrived, yellow being the old engine, and blue being the new engine after mapping.



Apologies for the awful image quality, I've got the printouts which I need to scan in at work, I've just not had the time!

So, how does it drive?

Brilliantly!

Power and torque is still progressive, and I've kept my approach of feeding the boost in gently still, rather than just smashing in 24psi as soon as it'll do it, I'm still only around 40% duty at spool up and in the mid range, so traction is still good (On a dry road!)

It feels much more eager than the old engine, very quick to get going, and very responsive to throttle changes.

Ignoring the exact figures for a second, and looking at the bigger picture, it's within 5% of the old peak power, and it's more than 5% up on torque. On the road it certainly FEELS faster, whilst still not being a handful.

Given that the engine was bought used, as an unknown entity, I was never expecting this to be a 'forever engine', more of a way to get me back on track, with reliable power, without spending the earth, and I think it's done that admirably.

We drank more tea, put the world to rights a little more. Discussed the incredible going ons of 2016, such as weddings, babies, Brexit, Trump, valves dropping, and which driveshafts to try in the Lupo next, then we drank some more tea again before it was time to head home to Hampshire where my pregnant wife was patiently waiting for me!

I have several conclusions about the results that I've come to since the day, that I'll discuss later. I'm keen to see what others think too.

Right now, I'm just SO happy to have the car back and driving so well again.

Massive thanks as always has to go to Bill and Tuffty. I love the days I spend at Badger 5, it's so much more than just a mapping session. It's a great catch up with good friends, it's learning more about the car and tuning in general, and it's also like being a kid in a sweet shop looking at all the things I can't afford but so badly want to buy when I grow up!

Great day. Great result.

Very happy.


Next Chapter: Bedford

antwan64og said:

Nick you're such a tease!

The dyno vid popped up on youtube but no write up.

I'm getting blue balls here!

Click to expand...

There you go Ant, just for you xxx (youtube stalker )

superkarl said:

Couple questions, AGU inlet manifold? I.e. LP runners?
And cams are N/A inlet cam, stock exhaust?

Click to expand...

Good questions SK, and I think the answer to one of them explains a good bit.

To start: I'm using the correct small port inlet manifold, with small port phenolic spacer also.

I'm using an N/A inlet cam, and turbo exhaust cam now. the old engine ran N/A cams on both sides.

Now, after a bit of searching, I found this post by myself, from 2013, written after installing both NA cams into my old large port engine with Ben Parsons and dyno runs before and after

Prawn said:

As tuffty found, there was small losses low down, although very small, and higher up after 5500rpm it holds onto the torque and power better than before, but due to the way my map tapers off at the top end currently, it's not making full use of the cams where they want to flow more.

On the road, it feels brilliant, the small losses low down cannot be felt, and the willingness to pull beyond 7k is very apparent, it feels more free

Click to expand...

I think this is potentially the big clue! Whilst others may not have seen huge gains from the N/A cams, it sounds like perhaps my chosen mapping approach and linear delivery may well have been so successful due to the N/A cam combination I ran previously. A small framed turbo making peak power at 7400rpm was, and still is, otherwise unheard of.

The engine now is behaving far more like a typical 20vt, so I'm unsure how much of that is down to the change to small port, and how much is down to the cam choice.

It'd be very interesting to see what would happen if I added the NA exhaust cam to the small port engine.

Possible outcomes as I see it:

• Would I regain some of the top end by holding onto torque beyond 6k better?
• Would I lose the torque gains seen lower down that we currently attribute to the change to small port?
• Best case: Would I keep the torque gains lower down AND gain the power back at the top?
• Or worst case: Would I lose the torque gains, and not gain anything more at the top due to the nature of the small port?

Not sure there's any way to accurately answer that, without physically making the change.

I'm not currently too fussed, as the car feels brilliant as it is, but it's certainly something to keep in the back of my mind. Perhaps if I find myself at a loose end one Sunday I'll swap the exhaust cam out and see what changes, but given our imminent arrival I'm not sure that's likely to happen any time soon!

There's an idea! n/a exhaust cam in, see what it does, and add VVT if I want to regain any lost spool / midrange.

Just ideas to think about for now. I wish I was brave enough to do a pikey cam change like Ben did back in 2012 but I'd probably mess it up!