[trackday_prep] Cameron's Mi16 / Gti6 Hybrid

[Cameron 16]

Right, its been a while since I did an update, mostly because I haven't really touched the car since the mapping session.

Anyway, here's a pic of the RR graph that shows the extent of my cam problem. The dotted red, blue and green lines are the original build's power, torque and AFR respectively. The solid lines are with the new cams and you can see that while it does start making good power above about 6.3K, it has lost out massively almost everywhere below. So although it has made 10bhp more, in the real world it would be much slower!

 

 

Those huge fluctuations in AFR are due to the pulsing caused by the cams. Nothing could be done to get rid of them!

 

So a few weeks ago (before going on holiday) I whipped the old cams out and decided to have some time off to think about what to do. Then after calling Newman today I decided to send the cams off to be reground. They should have them back to me by the end of the week, so I'll fit them as soon as they arrive. In the meantime I have fitted the original cams and my catcam verniers so I can get the car MOT'd. I've ordered some new tyres which should arrive on Wednesday, so MOT should be Thursday or Friday.

 

My next (and hopefully last) mapping session is Tuesday 11th August, then its going to be a few weeks shakedown before going off to the 'ring.

[DrSarty 90 1 Cars]

Best of luck Cam.

 

And dare I say it (yes I dare - but DO NOT wish to spoil your thread with 'that argument'), but doesn't this support what I keep saying that it's not about peak figures? High figures are nice, in fact desirable, but they need to compliment the shape of the power/torque curve. These new dips are what are ruining it in spite of the fact that you've gained 10 peak BHP right at the top. I'm sure you'd trade a few horses for a fatter delivery (?).

 

That's not directed at you Cam; it's a general comment on high figures not necessarily being best, nor the whole story.

Edited August 4, 2009 by DrSarty

[edbar 6]

Did you have any luck sorting the verniers? Havent touched mine yet.

[petert 591]

It looks like you didn't have enough compression ratio for the cams. What pistons did you use? It's a shame Newmans don't provide more data for their cams, as info on their website is a very general overview. What were the original cams?

[welshpug 1,662]

probably only about 10.9-1 if its stock mi16 pistons under a gti6 head, can't remember the spec and which page its on in those 28

[Cameron 16]

I worked it out to be something like 11.2:1 or something along those lines, which should be alright, shouldn't it? The cams are their tarmac rally / sprint cams that are supposed to have good midrange. The catalogue said that they need aftermarket management, but not mods to the induction so I expected them to work with the standard plenum. I also had to grind quite a bit out of the head to get them to rotate.

 

I measured the cams before I sent them off, and both measured 11.75mm of lift. I'm not sure weather I measured them right, as I subtracted the base circle diameter from the base circle + lobe height; done by measuring with my digi caliper. I guess it's right since the cams are 284 duration, so the profile is 284 / 2 = 142 degrees wide. But this doesn't match up to any of the data in the catalogue, phase 4 cams are supposed to be 11.17mm IN and 10.66mm EX.

 

The original cams were just standard GTi6 ones, Dave Walker reckoned that there was more power in the cam timing too, possibly 180-185bhp.

Edited August 4, 2009 by Cameron

[Cameron 16]

And dare I say it (yes I dare - but DO NOT wish to spoil your thread with 'that argument'), but doesn't this support what I keep saying that it's not about peak figures? High figures are nice, in fact desirable, but they need to compliment the shape of the power/torque curve. These new dips are what are ruining it in spite of the fact that you've gained 10 peak BHP right at the top. I'm sure you'd trade a few horses for a fatter delivery (?).

 

That's not directed at you Cam; it's a general comment on high figures not necessarily being best, nor the whole story.

 

Exactly right, shows that it's not all about peak gains! Its pointless having more oomph in the last 500rpm when you've lost out everywhere below that, where you're more likely to spend most of your time (unless you have a CVT ). If it had been Piper Cams and I had called them up I think I would have got a slightly different response. Something along the lines of: "Yeah, you made more power, what do you want!?"

[petert 591]

You're right, 11+:1 should be enough. Although it's easy to loose it rapidly when you start deepening the valve pockets in the pistons. Most likely the inlet manifold, etc.

[Cameron 16]

Engine is now back on standard cams and running very nicely!

Will do the MOT work tomorrow, and hopefully have it MOT'd on Thursday.

[DrSarty 90 1 Cars]

So what's the conclusion then please? Sorry to ask you to state the obvious, but what is so wildy different about the cams?

 

I don't mean reply with 'the profile Rich you dumb arse', but a bit of an explanation as to what is fundamentally different such as lift and duration, and is this a matter of compression.

 

I ask this as now it's back on standard cams - which I guess could be described as 'less aggressive' - is the cam/compression combination better which means you are happier with how it runs, despite it perhaps being down 10BHP again? Remember my engine's only on a stage I cam but is pushing 230BHP.

 

Really, genuinely interested in something here which perhaps looked good on paper and felt good going together, but actually doesn't seem to deliver. (Unless it was only ever offering 10 extra BHP right at the top and f*ck all elsewhere).

[Cameron 16]

Well I don't know what the standard duration is, but a PeterT stage 1 is 260 degrees and 8.9mm lift. The cams I tried were 284 degrees and 11.75mm lift so the overlap is considerably more! Its the overlap that is causing all the problems as it causes pulsing in the inlet. Its not a compression thing, you can see in the graph on the previous page that the fuelling cycles from rich to lean in the low revs, which I imagine is to do with the pulsing frequency (increasing with revs) and the harmonic frequency of the plenum (to get a bit tech).

Eventually the engine comes on cam, but its too little too late really. You can see that the power curve is still rising at the rev limit, so if I was revving the engine higher then it would make even more power, but it would still be gutless at lower revs which isn't what I want.

 

I've got a strong feeling that with more suitable cams it could make more peak power as well as better mid-range, since the peak in the power curve will be lower down, if that makes sense. Will wait and see.

[Cameron 16]

Been a busy boy again today, getting the car ready for its MOT tomorrow.

First off, I sorted out all the brake lines. The rears were easy peasy, just needed some zip ties, the fronts were a little more involved.

I had originally had them like this, my local MOT garage in Fleet told me that it was fine, but this place seems to be a bit more fussy.

 

 

So instead I decided to use the original clip points, wrapped the brake line in some spare fuel hose and zip tied it in place. Then I made a supporting eye out of some welding rod to keep the hose in the centre of the hole in the wing. Should be more then enough!

 

 

Then I decided to deal with the indicator flash rate, which was caused by me fitting LED bulbs. I swapped the bulbs over for normal ones, but for some reason they were still on super-flash mode, despite them all working! I tried another relay, but it was still going like the clappers! So, I did a bit of homework and found that you can modify the relay to remove the "bulb out" sensor. So I gave that a try and re-fitted the LED bulbs and it all works perfectly now.

For those who are interested its actually very simple, you remove the case from the relay and then cut the trace leading to pin 7 of the IC with a sharp knife. Put it all together, wahey! It works.

 

The last fiddly job was to sort out the rear fog lamp tell-tale, which I thought was going to be as easy as replacing the bulb, but no. I opened the switch to find no bulb holder so had to go to the scrap yard and get one! Then when I fitted it, it didn't work. After a bit of head scratching I found that the wiring to the switch was wrong, it had an earth for the bulb but no positive. So quickly wired it up and it works.

 

The only thing I haven't done is the tyres, but they did arrive today. I opted for some new A048's since they don't make 032's anymore, and got the soft compound to match my old ones. The thing is, I think they may have changed the compounds for 048's as these are very soft, about as soft as my super-soft rears. Anyone know if this is true? It could just be that there is more tread on them.

 

Mmm.. sticky.

 

 

And that's it, MOT prep done! Hoping it all stays together for tomorrow.

 

[DrSarty 90 1 Cars]

Well done Cam and good luck.

 

I like the way you've methodically gone down your failure sheet, writing in your rectifications AND ticking them all off down the left hand side.

 

Bet that gives you a nice warm feeling.

 

Now: how's this for random?

 

Talking of warm feelings: my best mate's older brother came round a few years ago with his Astra for me to fit a new CD player in. I was doing a proper job, heat shrinked wires etc and I took a break to stand up as my back was hurting a tad from being crunched up in the car.

 

My mate's brother was smiling and chatting with me about how it was going, and then there was this smell, much like hot rubber. His facial expression changed from a smile, into a look of concern and then a grimace, and then he jumped about 5 feet in the air with a yelp.

 

He was standing on my soldering iron, which had begun to melt through his shoe and start on his foot.

 

[Cameron 16]

Nice! I thought you were going to say your work had gone up in flames!

 

Yeah, I always do that so I can show the tester what I've actually done. I bet they hate it.

[welshpug 1,662]

those Soft A)48's are VERY soft! I wouldn't want to use them on the road as they'll wear out very quickly, also on a summers trackday they wont last but will be fantastically grippy.

 

they work VERY well in colder and even damp conditions, mediums everywhere else I would use personally, unless you like replacing them very often!

[Cameron 16]

Damn.. I thought they were going to be the same compound as my A032 softs.

Not to worry, I'll stick them on the back for now and see how they go. It won't be driven on the road much, just to & from the track / Germany.

[oli-pug 6 2 Cars]

Where did you order the tyres from Cam? Could you not get them swapped for mediums because they will wear very quickly, not cheap either i'm guessing!

[DrSarty 90 1 Cars]

I'm no expert at all on tyres; they're black magic to me.

 

But, and there is a point here: wouldn't you be better off driving to the 'Ring on some other wheels/tyres and fitting these bad boys when you get there?

 

This way their life wouldn't be worn down and you'd get better performance and value from them on the track where you surely want them; not on the road.

[welshpug 1,662]

Good idea DrS, bar the fact that where would you put the wheels whilst you and your mates are hooning?

 

I'd personally not use such a specific tyre for this purpose as the region the Ring is in is susceptible to very changeable weather, so a high performance road tyre would be rather more suitable

[TurboSam 5]

Not A048s, but R888s in soft after 3 laps of anglesey:

 

http://www.clubgti.com/forum/showthread.ph...light=SOFT+R888

 

If they are anything like that, they would be toast by AF !

Edited August 6, 2009 by TurboSam

[welshpug 1,662]

not surprised by that, they aren't a proper competition carcass like an AO48, just a soft compound on a road casing.

[Cameron 16]

Those are in super soft according to that, and that could well be down to the bloke's car and / or driving style.

 

To be honest, I never had any problems with my soft / super soft combo 032's out there, they did wear a bit but that's to be expected. Nowhere near that amount of death. I'm going to stick them on the rear for now, since there is more tread on them they'll be more prone to overheating, will be better off with less weight over them. My part worn SS rears can go on the front.

 

Sarty - WP basically said it for me, but I'd also need to fit 4 spare wheels in the boot along with all my spares and camping gear. I don't really see it happening.

 

High performance road tyres are all very well if you want to be economical, but I don't.

[Cameron 16]

Ps, the bloke I bought them off had them the other way round: super softs on the front and soft on the rear. He didn't have any problems like that despite having a few track days on them and there's plenty of life left in the SS's. It'll be fine.

[Cameron 16]

PPS.. It passed it's MOT!!

 

And, I got my insurance swapped over to Sky. Cost me £391 with everything declared and like for like mods. Thanks to bloke off here who's name I can't remember.

[tom_m 0]

sounds mate