Monday 25 April 2016
Friday 22 April 2016
Stagea Painting
This blog is slowly turning into "Stuff I have done with cars" rather than cobra specific.
Got the Stagea back from AK Bodycraft - who painted the cobra - and good heavens above what a great job they have done. Firstly, the wheels have been refurbished and they look pretty spectacular now. Powder coat centre with machined finish rim then clear coat over the top.
Spoiler re-done, this was terrible before, all blistered and nasty
Bumper repaired where the exhaust had melted it, and a drivers side scuff from a reversing accident (not shown in these photos)
aaaaand the big one - doors under the mirrors. Common on these cars.
Tadaaaaa....
Edited to add some better shots after polish and wax:
Got the Stagea back from AK Bodycraft - who painted the cobra - and good heavens above what a great job they have done. Firstly, the wheels have been refurbished and they look pretty spectacular now. Powder coat centre with machined finish rim then clear coat over the top.
Spoiler re-done, this was terrible before, all blistered and nasty
Bumper repaired where the exhaust had melted it, and a drivers side scuff from a reversing accident (not shown in these photos)
aaaaand the big one - doors under the mirrors. Common on these cars.
Tadaaaaa....
Edited to add some better shots after polish and wax:
Check out the lovely underseal and clean sills too:
Original and no doubt irreplaceable stickers still holding up well:
The completely unfathomable and ineffective "Light Reduce" button:
Reclining rear seats!
The famous turret tops now pristine and like new
Had a water pump failure which resulted in overheating so I plucked up the courage to do a precautionary head gasket change as it was showing some other symptoms of gasket failure. Turned out to be a good idea as cylinder 6 had gone and was chomping through coolant instead of lovely air and fuel. All back together and working as strong as ever.
Wednesday 20 April 2016
Rolling Road run with Quick Fuel 750DP
First cobra related post in ages!
The poor old cobra has been sat in the garage for 5 months and not even started. I pushed it about 2ft to access some tools but that's it. I never intended to leave it so long but trips abroad for work and then a 5 week holiday over Christmas meant I just never got round to driving it.
Anyway, last weekend we fired it up to attend a cobra club meeting. One pump of the throttle, turn the key and literally the first revolution of the engine it fired, as if it was impatient to get back outside. Drove to Corby (around 40 miles) to meet up with some other Cobra owners, which was nice.
The car was happy but I got it booked in for a rolling road session just to see if it could be improved. I have documented my low speed running problems on here in great detail and I was slowly coming round to thinking that its simply because of the engine combo and the fairly big cam and there wasn't much I could really do about it, apart from change my driving style and stay above 1800rpm.
I went to Wilshires Garage in Wimpole and met super-experienced Pete Baldwin who has about 50 years experience of Holley type carbs. Now - remember that being a young person, I've never owned a car with a carburettor before so I didn't know what was normal. Once I'd described the engine spec to Peter he agreed that if I want to chug around smoothly at low rpm then I should swap the cam for something softer. He said we would get it set up as best it could be but warned me not to expect miracles - its a limitation of the engine components. I was happy with that so we got stuck in.
Peter twiddled around with the timing while I held the revs steady to work out what the best all-in + vac cruise figure was. This was 45 degrees. With my mechanical + vacuum I was getting 42 so he recommended I give it 3 more degrees vac. We did a run where I held it at high revs and he adjusted the timing to find the best mechanical all in value. I had it at 34 based purely on knowledge that roughly 36 is the limit so I backed it off 2 degrees to be safe. We could see the HP on the screen and either side of 34.5 degrees the HP started to drop off so he agreed that it was set fine for the road. If I was racing and every single HP was critical then he would just nudge it up half a degree but it was perfectly acceptable for the road with a little margin to allow for poor quality fuel etc.
My IFR's and idle mixture were ok, perhaps a little rich on the IFR. Peter suggested I try the next size down but I explained that I had already tried that and it extended the light acceleration lean spot and made it quite noticeable so I was running it rich on purpose. He said that was ok as in those situations with micro-throttle movements the accel pump isn't doing much so that's the only solution. The reason behind all of this is the component combination. Big cam with lots of overlap means some of the fresh charge is wasted. At low engine speeds the big carb means that the air velocity is slow so the fuel metering isn't as good as it could be. The fuel comes through in globs rather than a nice even mixture. The third main problem is the single plane intake. Its a very large volume so the engine has to eat through all of the existing air/fuel charge in the plenum before it can get a richer charge when you crack the throttle open slightly.
On to power - we did a couple of power pulls. For reference, the old Edelbrock performer achieved 376bhp and 396lb.ft torque after A LOT of fiddling.
For power, all I've done with the Quick Fuel 750 as far as full power is concerned is jet down a couple of sizes across the board to get the WOT AFR to 12.5. This is what "felt" fastest to me on the road. It turns out that this was spot on. Peter suggested that for racing I should run slightly richer so maybe the out of the box setup of the carb was spot on but for the road I was ok. Here's the interesting bit - unfortunately I don't have a direct comparison between this carb and my previous one as I used a different rolling road but the power was 420bhp and torque was up to 430lb.ft. Peak torque was coming in a little lower in the rev range too, at 3400rpm.
From my research into annular boosters, I was expecting the peak torque to come in sooner which is good. I also have never heard of anyone swapping from Eddy to Holley and going slower so that was good too. I am still a little suspicious of such a large gain from 376 to 420 but there will be differences between different rolling roads so my conservative estimate is that I've probably gained somewhere around 25-30hp from going to Holley.
It was really interesting to talk to someone with extensive experience of driving engines like mine with hot cams.
Basically I need to adjust my driving style and stop expecting perfection in all driving conditions!
The poor old cobra has been sat in the garage for 5 months and not even started. I pushed it about 2ft to access some tools but that's it. I never intended to leave it so long but trips abroad for work and then a 5 week holiday over Christmas meant I just never got round to driving it.
Anyway, last weekend we fired it up to attend a cobra club meeting. One pump of the throttle, turn the key and literally the first revolution of the engine it fired, as if it was impatient to get back outside. Drove to Corby (around 40 miles) to meet up with some other Cobra owners, which was nice.
The car was happy but I got it booked in for a rolling road session just to see if it could be improved. I have documented my low speed running problems on here in great detail and I was slowly coming round to thinking that its simply because of the engine combo and the fairly big cam and there wasn't much I could really do about it, apart from change my driving style and stay above 1800rpm.
I went to Wilshires Garage in Wimpole and met super-experienced Pete Baldwin who has about 50 years experience of Holley type carbs. Now - remember that being a young person, I've never owned a car with a carburettor before so I didn't know what was normal. Once I'd described the engine spec to Peter he agreed that if I want to chug around smoothly at low rpm then I should swap the cam for something softer. He said we would get it set up as best it could be but warned me not to expect miracles - its a limitation of the engine components. I was happy with that so we got stuck in.
Peter twiddled around with the timing while I held the revs steady to work out what the best all-in + vac cruise figure was. This was 45 degrees. With my mechanical + vacuum I was getting 42 so he recommended I give it 3 more degrees vac. We did a run where I held it at high revs and he adjusted the timing to find the best mechanical all in value. I had it at 34 based purely on knowledge that roughly 36 is the limit so I backed it off 2 degrees to be safe. We could see the HP on the screen and either side of 34.5 degrees the HP started to drop off so he agreed that it was set fine for the road. If I was racing and every single HP was critical then he would just nudge it up half a degree but it was perfectly acceptable for the road with a little margin to allow for poor quality fuel etc.
My IFR's and idle mixture were ok, perhaps a little rich on the IFR. Peter suggested I try the next size down but I explained that I had already tried that and it extended the light acceleration lean spot and made it quite noticeable so I was running it rich on purpose. He said that was ok as in those situations with micro-throttle movements the accel pump isn't doing much so that's the only solution. The reason behind all of this is the component combination. Big cam with lots of overlap means some of the fresh charge is wasted. At low engine speeds the big carb means that the air velocity is slow so the fuel metering isn't as good as it could be. The fuel comes through in globs rather than a nice even mixture. The third main problem is the single plane intake. Its a very large volume so the engine has to eat through all of the existing air/fuel charge in the plenum before it can get a richer charge when you crack the throttle open slightly.
On to power - we did a couple of power pulls. For reference, the old Edelbrock performer achieved 376bhp and 396lb.ft torque after A LOT of fiddling.
For power, all I've done with the Quick Fuel 750 as far as full power is concerned is jet down a couple of sizes across the board to get the WOT AFR to 12.5. This is what "felt" fastest to me on the road. It turns out that this was spot on. Peter suggested that for racing I should run slightly richer so maybe the out of the box setup of the carb was spot on but for the road I was ok. Here's the interesting bit - unfortunately I don't have a direct comparison between this carb and my previous one as I used a different rolling road but the power was 420bhp and torque was up to 430lb.ft. Peak torque was coming in a little lower in the rev range too, at 3400rpm.
From my research into annular boosters, I was expecting the peak torque to come in sooner which is good. I also have never heard of anyone swapping from Eddy to Holley and going slower so that was good too. I am still a little suspicious of such a large gain from 376 to 420 but there will be differences between different rolling roads so my conservative estimate is that I've probably gained somewhere around 25-30hp from going to Holley.
It was really interesting to talk to someone with extensive experience of driving engines like mine with hot cams.
Basically I need to adjust my driving style and stop expecting perfection in all driving conditions!
Saturday 9 April 2016
Stagea trackday at Spa
For no reason other than "it will be hilarious" I went to Spa Francorchamps for a track day in the Stagea with some friends. The result? Well I survived, and so did the car. What a brilliant day. If you want to make friends, go on a track day with a Stagea! We paid extra to get a garage (good idea as it rained!) and our garage was full of people having a nosey all day long. There was nothing else like it there, the rest of the field was about 40% Porsche 911's piloted by fat middle aged businessmen in full racing suits, 30% BMW 3 series of various forms and the rest were track day special hatchbacks, Clio's, Corsas, Meganes etc and a smattering of Caterhams, and quite inexplicably a Le Mans prototype Lola-esque thing.
As far as the driving went, the car was a lot better than I expected, even though as suspected the brakes were the obvious weak link. On my first run out I did my outlap, one hot lap and then a gentle in-lap, but even on a slow in-lap you still have to brake a lot for some of the corners so I came into the garage with my brakes actually on fire. That earned us a lot of street cred. Went back out again and the brakes were still poo but I had learned to manage it and started building speed. I had some tuition to learn proper lines mainly for Eau Rouge, Blanchimont and the corner before Blanchimont which is critical to good speed down the straight. Oh and the downhill right hand haiprin Bruxelles, which no one could agree what the best line was. Even the good drivers seemed to all have different ideas there.
In the lunch break I bled the brakes as the pedal was very soft and squishy. Immediately after bleeding it was loads better - like the pedal was a block of wood so I had high hopes for the next session however the fluid I drained was nasty. I'm annoyed I didnt flush the fluid before going as it was very old. One hot lap after bleeding and the pedal was back to soft and squishy again so I just had to cope with it. I can only assume that the old fluid had so much water in that it was boiling really quickly.
Anyway, back to the circuit and after getting the tuition and getting more confident with the car I improved by 10 seconds a lap over the whole day and in the end did 3:30.9 which I was quite pleased with considering I've never done any track driving before. For reference there was a mid 90's non-wrx impreza doing roughly 3:27 and my friends new Fiesta ST with the 230 Mountune kit was getting 3:23 so I was very happy.
With it being Spa, obviously it chucked it down a couple of times and when it did I literally ran for my helmet and gloves and got straight out there and passed everyone else tiptoeing round then for 4 glorious half wet/half dry laps I was the only car on track, I had Spa to myself and didn't have to check my mirror every 2 seconds so had some serious fun and have gained new respect for the car as it handled everything brilliantly, including my cack handed driving.
The only damage I did to the car was on the rear bumper. It turns out that exhausts get very hot from prolonged spanking - all of the exhaust. I may have slightly set fire and melted the bumper where the exhaust exits, whoops!
In preparation for Spa and with no research at all I put some Michelin PS3's on. This car still has the original 16" wheels so they are 205/55 but the highest load rating, my logic being that with the high load rating they would have a fairly stiff sidewall so it wouldn't be too bad.
My logic just about held up (sort of). Please forgive my lack of in depth knowledge about these things, I'll try and describe as best I can what I did in case anyone is interested. Based on what my mate said (best source of info), when hot from track use the tyres would gain somewhere around 4psi. I carried a lot of tools there so I pumped my tyres up a bit due to the heavy load so I started off at 34 front / 36 rear (cold). We took an infra red temp gauge but completely forgot to use it so I just went on what it felt like to drive.
After the first run the tyres were up at 38 front / 40 rear so the 4psi guess seemed to hold. Now I know on the standard anti roll bar (sway bar for Americans) and standard suspension its a bit understeery. Also at the start of the day the track was damp and cold, about 7 deg C. Through trial and error and a bit of guidance and tuition the best way was to try and be gentle with initial turn in to prevent instant understeer overload of the front end and let the load build up. Once the car was settled in a bend it wasn't actually that bad. I carried on taking air out at 2psi at a time. I know 2psi is a lot but I purposely did large amounts so any difference would be obvious and we would be able to tell if we were going in the right/wrong direction with pressure.
After 3 morning runs I ended up with (hot) 31 front / 33 rear. This was still a little understeery mid corner so I dropped the fronts to 29. This seemed to cross some magical barrier where the front tyres just turned to jelly and it was awful. Had a moment at La Source where on the exit we just floated straight over the sleeping policeman onto the run off, much to the surprise of an Impreza following close behind who was probably expecting me to peel off to the right so he could pass.
After lunch the solution we ended up with was to put the fronts back to a hot pressure of 31psi and raise the rears to 35 (again, hot reading). Obviously there's several compromises going on at the same time here but applying the method of gentle initial turn in, then feel the load build, I was amazed that in long corners for example Bruxelles downhill off camber hairpin and Double Gauche/Pouhon (what a corner!) I could hold the steering wheel steady and modulate the throttle and bring the nose in/out of understeer/oversteer, then as the corner opens just nail the throttle and let it drift to the outside kerb. Obviously when I say "drift" I mean let the car smoothly run to the outside, not tyre screeching madness. In long corners like that I could feel the 4wd system working. You can't get power oversteer in the Stagea due to the automatic gearbox but if I nailed the throttle in the middle of Double Gauche it would understeer wide, then I could feel the front wheels come on and it would magically drag it back to the inside again. Just my own small experience only half knowing what I'm doing of course, but the 4wd system worked well even on such a big lumbering hulk of a car so I can only imagine how good a proper Skyline GTR would be around those same bends!
In preparation for Spa and with no research at all I put some Michelin PS3's on. This car still has the original 16" wheels so they are 205/55 but the highest load rating, my logic being that with the high load rating they would have a fairly stiff sidewall so it wouldn't be too bad.
My logic just about held up (sort of). Please forgive my lack of in depth knowledge about these things, I'll try and describe as best I can what I did in case anyone is interested. Based on what my mate said (best source of info), when hot from track use the tyres would gain somewhere around 4psi. I carried a lot of tools there so I pumped my tyres up a bit due to the heavy load so I started off at 34 front / 36 rear (cold). We took an infra red temp gauge but completely forgot to use it so I just went on what it felt like to drive.
After the first run the tyres were up at 38 front / 40 rear so the 4psi guess seemed to hold. Now I know on the standard anti roll bar (sway bar for Americans) and standard suspension its a bit understeery. Also at the start of the day the track was damp and cold, about 7 deg C. Through trial and error and a bit of guidance and tuition the best way was to try and be gentle with initial turn in to prevent instant understeer overload of the front end and let the load build up. Once the car was settled in a bend it wasn't actually that bad. I carried on taking air out at 2psi at a time. I know 2psi is a lot but I purposely did large amounts so any difference would be obvious and we would be able to tell if we were going in the right/wrong direction with pressure.
After 3 morning runs I ended up with (hot) 31 front / 33 rear. This was still a little understeery mid corner so I dropped the fronts to 29. This seemed to cross some magical barrier where the front tyres just turned to jelly and it was awful. Had a moment at La Source where on the exit we just floated straight over the sleeping policeman onto the run off, much to the surprise of an Impreza following close behind who was probably expecting me to peel off to the right so he could pass.
After lunch the solution we ended up with was to put the fronts back to a hot pressure of 31psi and raise the rears to 35 (again, hot reading). Obviously there's several compromises going on at the same time here but applying the method of gentle initial turn in, then feel the load build, I was amazed that in long corners for example Bruxelles downhill off camber hairpin and Double Gauche/Pouhon (what a corner!) I could hold the steering wheel steady and modulate the throttle and bring the nose in/out of understeer/oversteer, then as the corner opens just nail the throttle and let it drift to the outside kerb. Obviously when I say "drift" I mean let the car smoothly run to the outside, not tyre screeching madness. In long corners like that I could feel the 4wd system working. You can't get power oversteer in the Stagea due to the automatic gearbox but if I nailed the throttle in the middle of Double Gauche it would understeer wide, then I could feel the front wheels come on and it would magically drag it back to the inside again. Just my own small experience only half knowing what I'm doing of course, but the 4wd system worked well even on such a big lumbering hulk of a car so I can only imagine how good a proper Skyline GTR would be around those same bends!
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