Fix It Again Tomorrow - Street Sleeper
Discussion
Thanks for your comments
Anyhow, meanwhile Nats was eating the inner edges of her rear tyres:
And that is after the tyres were turned over at an earlier date as I was just too busy to do any more.
When this happens it's usually only one thing; the bearings in the rear swinging arms are worn out. They pivot on a pair of tapered bearings, when they wear out not only do you get too much camber:
But also they toe out too so wear out the tyres pretty quickly! Because they are tapered bearings under tension they don't show any movement when you stick the bar in and will still happily pass an MOT.
The parts are cheap, but It's a b1tch of a job, I was lucky here that I think they'd been done before as the through bolts were covered in grease so they came out. When they haven't and they get stuck in you're in for a much bigger job.
Camber afterwards:
It's the reading on the right of the gauge.
As we were prepping Project Sausage for this years onslaught of trackdays I decided to get it mapped again on one of our new ECUS. Last time we did it on Motec we had to stop at 478 bhp due to what we thought was electrical interference so I just left it there. This wasn't before I found this:
If you look carefully you can see the shiny part where the belt was hitting the crank sensor, yep that was what was making the signal go crazy.
I also changed the cam timing slightly and it was back at RS today for mapping, with Chubby Chops at the wheel (and his laptop) the result was more torque, earlier spool and more bhp so it's now pushing out 510bhp, 400ft/lbs and spooling up about 1000rpm earlier
Whilst they are often lazy beggars intent on doing as little as possible, I have to say I do have enormous admiration if not a little envy for a good mapper, the way they flit through the tables and screens making these things run is a fascinating sight - very skilled. I wish I could do my own, but whilst the obvious lack of rolling road is a problem it's very much a case of 'Man's gotta know his limitations' and no, I wouldn't feel very lucky (punk) so stick to what I know.
The turbo, injectors, fuel pump and other components are all pretty much near their maximum, so whilst well matched that's about as far as I can take this motor now.
Anyhow, meanwhile Nats was eating the inner edges of her rear tyres:
And that is after the tyres were turned over at an earlier date as I was just too busy to do any more.
When this happens it's usually only one thing; the bearings in the rear swinging arms are worn out. They pivot on a pair of tapered bearings, when they wear out not only do you get too much camber:
But also they toe out too so wear out the tyres pretty quickly! Because they are tapered bearings under tension they don't show any movement when you stick the bar in and will still happily pass an MOT.
The parts are cheap, but It's a b1tch of a job, I was lucky here that I think they'd been done before as the through bolts were covered in grease so they came out. When they haven't and they get stuck in you're in for a much bigger job.
Camber afterwards:
It's the reading on the right of the gauge.
As we were prepping Project Sausage for this years onslaught of trackdays I decided to get it mapped again on one of our new ECUS. Last time we did it on Motec we had to stop at 478 bhp due to what we thought was electrical interference so I just left it there. This wasn't before I found this:
If you look carefully you can see the shiny part where the belt was hitting the crank sensor, yep that was what was making the signal go crazy.
I also changed the cam timing slightly and it was back at RS today for mapping, with Chubby Chops at the wheel (and his laptop) the result was more torque, earlier spool and more bhp so it's now pushing out 510bhp, 400ft/lbs and spooling up about 1000rpm earlier
Whilst they are often lazy beggars intent on doing as little as possible, I have to say I do have enormous admiration if not a little envy for a good mapper, the way they flit through the tables and screens making these things run is a fascinating sight - very skilled. I wish I could do my own, but whilst the obvious lack of rolling road is a problem it's very much a case of 'Man's gotta know his limitations' and no, I wouldn't feel very lucky (punk) so stick to what I know.
The turbo, injectors, fuel pump and other components are all pretty much near their maximum, so whilst well matched that's about as far as I can take this motor now.
Edited by Evoluzione on Thursday 9th April 07:16
Loving the writing, lots of nuggets of information that bust some of the common internet myths (ie. port & polish, obvious when you think about it).
As a result (and after reading a fair bit of Dave Walkers musings), I'm a lot less scared of using electronics under the bonnet than I used to be.
Evoluzione said:
Whilst they are often lazy beggars intent on doing as little as possible, I have to say I do have enormous admiration if not a little envy for a good mapper, the way they flit through the tables and screens making these things run is a fascinating sight - very skilled.]
It is, isn't it. We had our Ginetta engine swap mapped by RS a couple of years ago and they got a lovely driveable car out of it while being honest (so many are not) about the power available with the kit we're running.As a result (and after reading a fair bit of Dave Walkers musings), I'm a lot less scared of using electronics under the bonnet than I used to be.
Thanks again for all the replies.
I didn't really go into much detail over inlet port finish as it is a subject all on its own and there are two reasons for a rough port wall.
Again with older style engines we are dealing with two types of 'fluid'; air and petrol, this means a port is a compromise and why DI is king as we can take one out of the equation and just deal with air going through a port, this makes it much simpler and effective.
Modern engines need highly atomised fuel to be efficient, when fuel is travelling down a port it gets splashed all over the place and down the port walls (floor and roof!), we need to reintroduce it into the airflow so here is an easy to understand principle:
Spray some water onto a piece of glass, blow it with air, see it bead and run off in large drops.
Spray water onto sandpaper, blow it with air and it will leave in a much finer form.
And it's as simple as that
The other phenomenon is something called 'The Boundary layer'.
This is a layer of air which exists on the outside of the main body of air, against the wall of whatever it is travelling past - in this case the port walls. When the surface is rough this boundary layer is known as 'turbulent' as it tumbles over itself (as opposed to laminar which is layered, uniform and smooth).
The main body of air uses this tumbling outer layer to keep itself attached to the port and in turn moves faster: Two easy to understand examples:
Two golf balls, one smooth, one with dimples, which one flies the farthest? The one with dimples and by quite some margin.
Kids sliding on a varnished wooden floor, introduce some marbles and see how much further they go!
Diagrams of the golf ball analogy:
Now as we can see there, it's about leaving a smaller wake and 're-attaching the flow', this leads us to this little pic here:
And then here below you can see how the engine designers have incorporated that piece of aerodynamic design into the ports so the flow reattaches itself after it's been around the valve guide:
It's nothing new, people have been using this for years, but once you start to study airflow (often with the aid of a flowbench) you start to notice this kind of stuff here and there and it clicks into place why it is there. Everyday out on the road you will see 'flow straighteners' or 'turning vanes', but not even realise it, when you do you think fk me, I never knew what those were for and i've been looking at them for 20 - 30 yrs!
You can apply some of this theory to inlet ports, it's only worth a few bhp for each successful feature, but when added up they can make a significant improvement, especially in a highly competitive race car.
Mark Benson said:
Loving the writing, lots of nuggets of information that bust some of the common internet myths (ie. port & polish, obvious when you think about it).
As a result (and after reading a fair bit of Dave Walkers musings), I'm a lot less scared of using electronics under the bonnet than I used to be.
I've always liked reading Dave Walkers words, he always seemed very honest and willing to go that extra mile for customers, where does he write these days? I know it used to be CCC and then PPC.Evoluzione said:
Whilst they are often lazy beggars intent on doing as little as possible, I have to say I do have enormous admiration if not a little envy for a good mapper, the way they flit through the tables and screens making these things run is a fascinating sight - very skilled.]
It is, isn't it. We had our Ginetta engine swap mapped by RS a couple of years ago and they got a lovely driveable car out of it while being honest (so many are not) about the power available with the kit we're running.As a result (and after reading a fair bit of Dave Walkers musings), I'm a lot less scared of using electronics under the bonnet than I used to be.
I didn't really go into much detail over inlet port finish as it is a subject all on its own and there are two reasons for a rough port wall.
Again with older style engines we are dealing with two types of 'fluid'; air and petrol, this means a port is a compromise and why DI is king as we can take one out of the equation and just deal with air going through a port, this makes it much simpler and effective.
Modern engines need highly atomised fuel to be efficient, when fuel is travelling down a port it gets splashed all over the place and down the port walls (floor and roof!), we need to reintroduce it into the airflow so here is an easy to understand principle:
Spray some water onto a piece of glass, blow it with air, see it bead and run off in large drops.
Spray water onto sandpaper, blow it with air and it will leave in a much finer form.
And it's as simple as that
The other phenomenon is something called 'The Boundary layer'.
This is a layer of air which exists on the outside of the main body of air, against the wall of whatever it is travelling past - in this case the port walls. When the surface is rough this boundary layer is known as 'turbulent' as it tumbles over itself (as opposed to laminar which is layered, uniform and smooth).
The main body of air uses this tumbling outer layer to keep itself attached to the port and in turn moves faster: Two easy to understand examples:
Two golf balls, one smooth, one with dimples, which one flies the farthest? The one with dimples and by quite some margin.
Kids sliding on a varnished wooden floor, introduce some marbles and see how much further they go!
Diagrams of the golf ball analogy:
Now as we can see there, it's about leaving a smaller wake and 're-attaching the flow', this leads us to this little pic here:
And then here below you can see how the engine designers have incorporated that piece of aerodynamic design into the ports so the flow reattaches itself after it's been around the valve guide:
It's nothing new, people have been using this for years, but once you start to study airflow (often with the aid of a flowbench) you start to notice this kind of stuff here and there and it clicks into place why it is there. Everyday out on the road you will see 'flow straighteners' or 'turning vanes', but not even realise it, when you do you think fk me, I never knew what those were for and i've been looking at them for 20 - 30 yrs!
You can apply some of this theory to inlet ports, it's only worth a few bhp for each successful feature, but when added up they can make a significant improvement, especially in a highly competitive race car.
MegaMinion said:
I fking love fluids!
Awesome write by the way, despite the fact that I've spent all day at uni sat doing CFD and getting home and wanting to do anything but fluid related things I thoroughly enjoyed reading that.
Haha, yes it's an interesting subject when you start looking into it, you'll know much more than me though!Awesome write by the way, despite the fact that I've spent all day at uni sat doing CFD and getting home and wanting to do anything but fluid related things I thoroughly enjoyed reading that.
Just a bit of an update on Project Sausage.
At a Spring trackday it seemed to me we were getting a bit of 'surprise over steer', it could have been just me, but it seemed to throw me off once when I didn't think i'd lifted, I reckoned the rear end needed an overhaul.
So over the Summer I removed the rear subframe as the rear swinging arm bearings were shot, not only that, but the through bolts were seized in place so I couldn't even get them off with it in place. Whilst it was off I took the opportunity to fit a thicker rear ARB and Poly subframe mounts in place of the old rubber ones.
De rusting and painting would have been good, but I just CBA and it wouldn't have made it go faster. They are made from seriously thick steel and cast iron too.
The clutch was replaced as a matter of course as it had been on a few years and seen a lot of abuse. The actual cerametallic pads on the friction plate were barely worn, but the cover plate friction face was. I just wanted to avoid going to do a TD and the thing failing on me. While the box was off I stripped and rebuilt that too - again, just incase. Everything looked fine which was a relief as they are known for letting go if abused.
Again another 'Well whilst you're at it you might aswell' job with the front subframe. I removed it and fitted a very slightly thicker front ARB (the rear was a much thicker increase). This isn't mine, just a random internet pic:
So you can see the layout. If you look closely you can see the spot welds, it's said that it can flex so I put some seam welds here and there too.
The whole lot was put back together again and off we went to Blyton Park, it's too small and twisty for a big heavy long legged car like the Coupe, but I had a learner with me so not much choice - there isn't much to hit at Blyton. A few pics of the day:
As you can see she corners pretty flat now with what I would say is just enough roll, I managed not to spin anyhow and she felt pretty solid all day.
I've now amassed far too many projects though so am sadly thinking of letting the Coupes go this Autumn, i've got a full 4wd system for one kicking around too, but I just don't have the time to spend with them although I'll miss them if they do go.
At a Spring trackday it seemed to me we were getting a bit of 'surprise over steer', it could have been just me, but it seemed to throw me off once when I didn't think i'd lifted, I reckoned the rear end needed an overhaul.
So over the Summer I removed the rear subframe as the rear swinging arm bearings were shot, not only that, but the through bolts were seized in place so I couldn't even get them off with it in place. Whilst it was off I took the opportunity to fit a thicker rear ARB and Poly subframe mounts in place of the old rubber ones.
De rusting and painting would have been good, but I just CBA and it wouldn't have made it go faster. They are made from seriously thick steel and cast iron too.
The clutch was replaced as a matter of course as it had been on a few years and seen a lot of abuse. The actual cerametallic pads on the friction plate were barely worn, but the cover plate friction face was. I just wanted to avoid going to do a TD and the thing failing on me. While the box was off I stripped and rebuilt that too - again, just incase. Everything looked fine which was a relief as they are known for letting go if abused.
Again another 'Well whilst you're at it you might aswell' job with the front subframe. I removed it and fitted a very slightly thicker front ARB (the rear was a much thicker increase). This isn't mine, just a random internet pic:
So you can see the layout. If you look closely you can see the spot welds, it's said that it can flex so I put some seam welds here and there too.
The whole lot was put back together again and off we went to Blyton Park, it's too small and twisty for a big heavy long legged car like the Coupe, but I had a learner with me so not much choice - there isn't much to hit at Blyton. A few pics of the day:
As you can see she corners pretty flat now with what I would say is just enough roll, I managed not to spin anyhow and she felt pretty solid all day.
I've now amassed far too many projects though so am sadly thinking of letting the Coupes go this Autumn, i've got a full 4wd system for one kicking around too, but I just don't have the time to spend with them although I'll miss them if they do go.
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