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GarryA
2,545 posts
34 months
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I think there was a couple of myths about the BMW motors.....
They only used blocks that had done over 100k as they had work hardened.
They used to leave the blocks outside and the workers used to piss on them.
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chuntington101
4,092 posts
106 months
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Marf said: renorti said: amazing fact the engine block was from a production 1500cc bmw saloon which they stood outside to weather a bit until surface rust appeared then modified it for use. Always wondered if that was an urban myth or not. There are similar stories floating around regarding the Nissan RB26 blocks used in GpA racing. How could the RB26 be used? Its to long to fit transverse as the Nissan Sunny GTiR used it for Group A Rallying. Also its a 2.6ltr, which is against the regs is it not?......
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Marf
22,907 posts
111 months
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chuntington101 said: Marf said: renorti said: amazing fact the engine block was from a production 1500cc bmw saloon which they stood outside to weather a bit until surface rust appeared then modified it for use. Always wondered if that was an urban myth or not. There are similar stories floating around regarding the Nissan RB26 blocks used in GpA racing. How could the RB26 be used? Its to long to fit transverse as the Nissan Sunny GTiR used it for Group A Rallying. Also its a 2.6ltr, which is against the regs is it not?......  I wasn't suggesting that it would be used in F1, just saying I'd heard that Nissan also used old apparently weather hardened blocks in their GpA Skylines back in the day.
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compocon
Original Poster
137 posts
34 months
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Group A Touring Cars not Rallying!
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dvs_dave
3,623 posts
95 months
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renorti said: being a40year old,i was lucky enough to have seen the turbo era,it was my favourite era of f1 by far.those 1500cc turbo's did give amazing power,bmw powered brabham was meant to produce 1200hp for qualify laps,about 850 in race trim.amazing fact the engine block was from a production 1500cc bmw saloon which they stood outside to weather a bit until surface rust appeared then modified it for use. When I was at Uni (UMIST), they had a Cosworth F1 engine which was a 1500cc V6 TT running 1500 bhp in qualifying trim. 
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chuntington101
4,092 posts
106 months
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compocon said: Group A Touring Cars not Rallying! Aaaahhh yes i understand now. 
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Henry Mi16
1 posts
32 months
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The ~2000bhp 1.5L v6 designed by Geoff was a compound turbo design that transmitted power direct to the crank via a CVT and was banned after one event. Unless I misunderstood the lecture!  Another interesting point is when they restricted boost from 8bar to 4bar he simply expanded the gas so rapidly as to ahcieve -36degree inlet temps. Bring back the 80s??
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chuntington101
4,092 posts
106 months
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Henry Mi16 said: The ~2000bhp 1.5L v6 designed by Geoff was a compound turbo design that transmitted power direct to the crank via a CVT and was banned after one event. Unless I misunderstood the lecture! Another interesting point is when they restricted boost from 8bar to 4bar he simply expanded the gas so rapidly as to ahcieve -36degree inlet temps. Bring back the 80s?? I have heard WRC cars doing this, have you got any idea as to how they did it? Chris.
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Max_Torque
4,924 posts
87 months
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Basically you put another throttle / restrictor down stream of the intercooler, the turbo runs at a higher boost pressure than you require in the plenum, and you drop this "excess" pressure across the restrictor. Now, that actually takes more exhaust energy to do (as the turbo is doing more work) so reduces engine performance. The key point is that you are boosting the effectiveness of the intercooler to over 100%, becuase your high pressure air exiting the compressor is V hot, you have a large delta T to ambient, so your aftercooling system is able to remove lots of heat. (you remove heat at the highest enthalpy point of the system) Then when you allow the air to expand post IC (at a lower enthalpy) it is cooled BELOW ambient temperature by that expansion. (assuming that you expand it fast enough and at a point of poor thermal conduction to the environment, so the energy required for the expansion (change of entropy) has to take heat from the gas itself)
If you have an engine that is heavily knock limited, where it's sensitivity to intake air temperature is very steep, you can find that the extra turbo work is more than offset by the combustion pressure gains from the cold aircharge / advanced ignition, so overall it's a win = more power.
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Transmitter Man
2,570 posts
94 months
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"Basically you put another throttle / restrictor down stream of the intercooler, the turbo runs at a higher boost pressure than you require in the plenum, and you drop this "excess" pressure across the restrictor. Now, that actually takes more exhaust energy to do (as the turbo is doing more work) so reduces engine performance. The key point is that you are boosting the effectiveness of the intercooler to over 100%, becuase your high pressure air exiting the compressor is V hot, you have a large delta T to ambient, so your aftercooling system is able to remove lots of heat. (you remove heat at the highest enthalpy point of the system) Then when you allow the air to expand post IC (at a lower enthalpy) it is cooled BELOW ambient temperature by that expansion. (assuming that you expand it fast enough and at a point of poor thermal conduction to the environment, so the energy required for the expansion (change of entropy) has to take heat from the gas itself) If you have an engine that is heavily knock limited, where it's sensitivity to intake air temperature is very steep, you can find that the extra turbo work is more than offset by the combustion pressure gains from the cold aircharge / advanced ignition, so overall it's a win = more power." May I have one of them for the TVR please? Phil  TVR 420 SEAC
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Huff
1,156 posts
61 months
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Marf said: chuntington101 said: Marf said: renorti said: amazing fact the engine block was from a production 1500cc bmw saloon which they stood outside to weather a bit until surface rust appeared then modified it for use. Always wondered if that was an urban myth or not. There are similar stories floating around regarding the Nissan RB26 blocks used in GpA racing. How could the RB26 be used? Its to long to fit transverse as the Nissan Sunny GTiR used it for Group A Rallying. Also its a 2.6ltr, which is against the regs is it not?...... I wasn't suggesting that it would be used in F1, just saying I'd heard that Nissan also used old apparently weather hardened blocks in their GpA Skylines back in the day. I wish I could remember where I read about all this in detail... Yes, early prototypes definitely were based on reclaimed production BMW blocks. The reason was simply to ensure adequate stress-relief via many heat cycles. Cast iron is very susceptible to locked-in stresses as-cast, and machined new castings often 'move' - a lot. Using the 'aged' production blocks allowed design development to proceed using a proven lump. Race engines then all used a custom casting, which took onboard lessons learned. These were left some months before machining, to deal with locked-in stresses; (such'seasoning' is nothing new to cast-iron technologies) and simply left outside, from expediency of storage. Rust in and of itself isn't beneficial. I'd add - ammonia atmospheres definitely do have a place under controlled elevated temperatures to case-harden (e.g. nitriding). Room-temperature micturation doesn't count, so I'm sure that bit is just myth
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compocon
Original Poster
137 posts
34 months
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The precision the drivers demonstrated with so much power over such a small rev band is truly incredible. Epic qualifying video: http://www.youtube.com/watch?v=cL3i_NQ9S0gI guess this must be when they were running well over 1000bhp??
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GavinPearson
5,034 posts
121 months
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Really nice video to watch, given a choice between the racing of 25 years ago and that of today, I'll pick the racing of 25 years ago.
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Max_Torque
4,924 posts
87 months
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Just watched the Mansell bit, and thought, well it's ok i guess, he's not going THAT fast. Then he started his actual timed lap..... lol! blimey, they certainly ran a bit rich in qually trimm back then !!
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chuntington101
4,092 posts
106 months
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Max_Torque said: Basically you put another throttle / restrictor down stream of the intercooler, the turbo runs at a higher boost pressure than you require in the plenum, and you drop this "excess" pressure across the restrictor. Now, that actually takes more exhaust energy to do (as the turbo is doing more work) so reduces engine performance. The key point is that you are boosting the effectiveness of the intercooler to over 100%, becuase your high pressure air exiting the compressor is V hot, you have a large delta T to ambient, so your aftercooling system is able to remove lots of heat. (you remove heat at the highest enthalpy point of the system) Then when you allow the air to expand post IC (at a lower enthalpy) it is cooled BELOW ambient temperature by that expansion. (assuming that you expand it fast enough and at a point of poor thermal conduction to the environment, so the energy required for the expansion (change of entropy) has to take heat from the gas itself)
If you have an engine that is heavily knock limited, where it's sensitivity to intake air temperature is very steep, you can find that the extra turbo work is more than offset by the combustion pressure gains from the cold aircharge / advanced ignition, so overall it's a win = more power.
that sounds pretty intresting ad very 'do able'. Have you got any pictures of a setup? In the WRC scooby i saw the pipework from the intercooler was maybe 2-2.5inch diammeter and then the was a sudden transition to about 4inch pipework to the throttle body and intake manifold. Would this be enough to offer the presure drop? also could this be done at the mnaifold? Just thinking that probably a easiet location to offer a BIG diammeter increase in pipework...... Chris.
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chuntington101
4,092 posts
106 months
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Here is a link to what i mentioned above. http://www.google.co.uk/imgres?imgurl=http://www.w...You can clearly see on the right hand side of the engine bay, theboost pipe leading from the front to the back of the car exspands to something like 4-5inch pipe work . Is this the reduce intake temps?????........
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HowlerMonkey
86 posts
39 months
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On a related theme, I saw this car over the weekend as well as destroyed engine parts from an earlier motor. 
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Evoluzione
968 posts
113 months
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Max_Torque said: It interesting to see they all have pre-compressor throttles (and one has a very nice quartic twist throttle!!) to try to maximise shaft rpm during shifts / lifts etc! Must have playyed hell with the compressor oil seals, but i guess an f1 race is pretty short, and the odd puff of oil being burnt wasnt the end of the world?? How do these 'Pre-compressor throttles' work Max?
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HowlerMonkey
86 posts
39 months
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They are creating as low a pressure as possible in the compressor section when the car is lifting by using the closed throttle body upstream.
This reduces the rpm drop of the turbo because the air that the compressor is trying to push is much less dense.
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Tango13
2,654 posts
46 months
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The book you need is called 'The 1000 BHP Grand Prix Car' I'll post up the author and ISBN when I get home.
It details the evoloution of the turbo car from the early Renaults all the way to the last of the Hondas.
It's long out of print but I imagine a good 2nd hand book shop should be able to source a copy.
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