Black Betty - Part 3 Engine rebuild
03-19-2013, 03:32 PM
#496
Burning Brakes
http://rothsport-racing.com/Products...ide-Valve.html
A slide valve "throttle body".
Rather than the induction flap operating on the vertical axis, the slide valve operates on a horizontal axis.
Daddy wants!!!
A slide valve "throttle body".
Rather than the induction flap operating on the vertical axis, the slide valve operates on a horizontal axis.
Daddy wants!!!
03-19-2013, 05:44 PM
#498
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So glad to see Betty is back, hoping you make a full recovery for Spa.
Even though a lot of technical aspects are beyond me I've really enjoyed reading the thread and look forward to the Spa vids and seeing that engine in the metal at a future London meet.
Enjoy!
Even though a lot of technical aspects are beyond me I've really enjoyed reading the thread and look forward to the Spa vids and seeing that engine in the metal at a future London meet.
Enjoy!
03-19-2013, 06:01 PM
#499
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?Wet weather, snow C4 performance is superfluous for my application. Other aspects of the C4 work for me. Power delivery, available traction, stability. Remember that road tests found the C4 in many instances quicker 0-60, specifically off the line. To me the C4 feels sure footed, rarely unsettled under braking, cornering and acceleration out of tight corners. With the HP I'm now delivering I'm confident the C4 platform will work wonders.
The important element I can take away is that power means nothing without application. Dyno plots are not real world analysis. It's clear that whilst a C4 has a higher transmission loss (est 28% loss) and weight (est + 100kg) it makes up for it in traction based on the aforementioned 0-60. Which in my book is one hell of an achievement.
Now that is not to say I am an expert by any stretch - my view is my own and based on past C2s that I have driven/ spent time with.
All this to say that the advantages/ disadvantages to both variants go far and away beyond weather.
Can't disagre with your logic or decision making, Frank. The most fun I ever had in a non-RS 964 was in this Carrera 4; it was an absolute blast to floorboard the throttle mid-corner and feel the front wheel torque drag the car from understeer to oversteer at a truly insane speed. Mind you, the 500hp turbo we fitted in the back probably helped!
Your car is going to be fantastic, be sure to enjoy every moment of driving it that you can.
etc
03-20-2013, 05:53 AM
#501
?Wet weather, snow C4 performance is superfluous for my application. Other aspects of the C4 work for me. Power delivery, available traction, stability. Remember that road tests found the C4 in many instances quicker 0-60, specifically off the line. To me the C4 feels sure footed, rarely unsettled under braking, cornering and acceleration out of tight corners. With the HP I'm now delivering I'm confident the C4 platform will work wonders.
The important element I can take away is that power means nothing without application. Dyno plots are not real world analysis. It's clear that whilst a C4 has a higher transmission loss (est 28% loss) and weight (est + 100kg) it makes up for it in traction based on the aforementioned 0-60. Which in my book is one hell of an achievement.
Now that is not to say I am an expert by any stretch - my view is my own and based on past C2s that I have driven/ spent time with.
All this to say that the advantages/ disadvantages to both variants go far and away beyond weather.
That is not to say my needs/ views on the C4 may change. I do however feel that EvoGT2 uprights are a natural point of evolution especially for C4 track cars - that is where I feel a weakness in the platform.
To give you an idea of how much more you got out of your rebuild, my 3.8 did 306.9bhp at 6600rpm (and 264.1 lb ft at 4750rpm). So you've got way more hp than mine, even before you get it finished.
Agree with you completely on your analysis, too. C2 and C4 are very different animals each with their own positives and negatives. BB is going to be a road and track beast...
Cannot wait to see (and hear - get a video up soon!) her in the metal. Have fun at Spa!
Ben
03-20-2013, 06:16 AM
#502
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Hi Frank,
How's your wrist?
What made you rethink your plans from the more traditional (Weber looking) PMO's to the slide valves, was it pure performance, looks, reliability or all three?
It doesn't look like a money saving exercise
Cheers,
Paul
How's your wrist?
What made you rethink your plans from the more traditional (Weber looking) PMO's to the slide valves, was it pure performance, looks, reliability or all three?
It doesn't look like a money saving exercise
Cheers,
Paul
03-20-2013, 07:31 AM
#503
Drifting
Thread Starter
Yup was mapped on road and 4WD dyno.
Thanks for the kind words - glad it's been interesting. 
Cheers mate, look forward to meeting you at a L964O meet. Hope you're all happily settled in Epsom.
Cheers mate. Look forward to catching up. It seems we're producing the same torque but at different revs - 264.2lb @6,600.
Hi Paul, flat-slides were always the plan - they just weren't ready in time. Nick kindly chucked on PMOs to get me to SPA....
Can't disagre with your logic or decision making, Frank. The most fun I ever had in a non-RS 964 was in this Carrera 4; it was an absolute blast to floorboard the throttle mid-corner and feel the front wheel torque drag the car from understeer to oversteer at a truly insane speed. Mind you, the 500hp turbo we fitted in the back probably helped!
Your car is going to be fantastic, be sure to enjoy every moment of driving it that you can.
Your car is going to be fantastic, be sure to enjoy every moment of driving it that you can.
Cheers mate, look forward to meeting you at a L964O meet. Hope you're all happily settled in Epsom.
Frank, congrats it sounds epic and can't wait to see what the numbers turn out to be when the flat slides are on...
To give you an idea of how much more you got out of your rebuild, my 3.8 did 306.9bhp at 6600rpm (and 264.1 lb ft at 4750rpm). So you've got way more hp than mine, even before you get it finished.
Agree with you completely on your analysis, too. C2 and C4 are very different animals each with their own positives and negatives. BB is going to be a road and track beast...
Cannot wait to see (and hear - get a video up soon!) her in the metal. Have fun at Spa!
Ben
To give you an idea of how much more you got out of your rebuild, my 3.8 did 306.9bhp at 6600rpm (and 264.1 lb ft at 4750rpm). So you've got way more hp than mine, even before you get it finished.
Agree with you completely on your analysis, too. C2 and C4 are very different animals each with their own positives and negatives. BB is going to be a road and track beast...
Cannot wait to see (and hear - get a video up soon!) her in the metal. Have fun at Spa!
Ben
Hi Paul, flat-slides were always the plan - they just weren't ready in time. Nick kindly chucked on PMOs to get me to SPA....
03-20-2013, 07:32 AM
#504
Three Wheelin'
Frank , if you can in future , a close ratio gearbox would be a great improvement , you would keep it in the the power band but more important you would be loading at the right time so more grip and better handling ...
03-20-2013, 12:18 PM
#506
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03-20-2013, 06:20 PM
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03-21-2013, 09:05 AM
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Relating this to Frank's engine (and so keeping nicely on topic!), with the relatively flat torque curve is appears that the cam selection by Nick was reasonably conservative, therefore it might pay to measure the engines MAP characteristics once the slide throttles are fitted, then consider the inclusion of a vacuum plenum into the plan if it seems feasible.
Of course, the other option is to run oversize vacuum pipes to a plenum then install the 964 or 993 idle speed valve with a little K&N filter on the end, the Motec system has two PWM (pulse width modulated) outputs which can be used effectively to control the operation of the valve. Indeed, having the ISV working properly is one of the primary advantages to running Motec on any 964 engine as a steady idle with super lightweight flywheels then becomes a breeze.
03-21-2013, 09:23 AM
#510
Drifting
Thread Starter
Relating this to Frank's engine (and so keeping nicely on topic!), with the relatively flat torque curve is appears that the cam selection by Nick was reasonably conservative, therefore it might pay to measure the engines MAP characteristics once the slide throttles are fitted, then consider the inclusion of a vacuum plenum into the plan if it seems feasible.