Knackered old Porsche with loads of natural light - Boxster!
Discussion
Escy said:
I assume this is how the air flow works for the intercooler on the air cooled 911 Turbos?
Exactly, higher pressure on the inlet and lower pressure on the exit = flow. Vary one and the flow varies accordingly. The exits on the 996 are in a super low pressure area, you can see the same thing here on the 986 trailing sections of the rear bumper:
Spent some time at CG this afternoon discussing damper options and how a suspension kit for "Boosters" is going to come together. Part of this was weighing the car:
1259KG with about 35KG of fuel onboard.
At these weights we have a front/rear distribution of 47.58% front and 52.42% rear. A standard 2.5 Boxster is 47% front and 53% rear accordingly to Porsche so we are within 0.5% and change of the original weight distribution. Give we are 52KG - 57KG lighter than a standard car (based on those CG have previously measured and on this one prior to the repower) it was definitely worth sneaking a few KG's into the front engine mount as ballast to keep the balance as per original!
1259KG with about 35KG of fuel onboard.
At these weights we have a front/rear distribution of 47.58% front and 52.42% rear. A standard 2.5 Boxster is 47% front and 53% rear accordingly to Porsche so we are within 0.5% and change of the original weight distribution. Give we are 52KG - 57KG lighter than a standard car (based on those CG have previously measured and on this one prior to the repower) it was definitely worth sneaking a few KG's into the front engine mount as ballast to keep the balance as per original!
poppopbangbang said:
Spent some time at CG this afternoon discussing damper options and how a suspension kit for "Boosters" is going to come together. Part of this was weighing the car:
1259KG with about 35KG of fuel onboard.
At these weights we have a front/rear distribution of 47.58% front and 52.42% rear. A standard 2.5 Boxster is 47% front and 53% rear accordingly to Porsche so we are within 0.5% and change of the original weight distribution. Give we are 52KG - 57KG lighter than a standard car (based on those CG have previously measured and on this one prior to the repower) it was definitely worth sneaking a few KG's into the front engine mount as ballast to keep the balance as per original!
Was that without driver? Very good balance across the corners!!1259KG with about 35KG of fuel onboard.
At these weights we have a front/rear distribution of 47.58% front and 52.42% rear. A standard 2.5 Boxster is 47% front and 53% rear accordingly to Porsche so we are within 0.5% and change of the original weight distribution. Give we are 52KG - 57KG lighter than a standard car (based on those CG have previously measured and on this one prior to the repower) it was definitely worth sneaking a few KG's into the front engine mount as ballast to keep the balance as per original!
Mikeeb said:
Was that without driver? Very good balance across the corners!!
Yes without driver, which would obviously impact the balance across the corners somewhat but pretty good considering: - It's on 25 year old springs and dampers
- Suspension wise it's as it came from Porsche
- I've completely changed the power unit for one with a sodding great turbo and cast manifold hanging off one side of it....
Two things jump out from this, the first is Porsche really know how to design a car
, the second is that I got my engine masses pretty decent with the mass of the charge cooler, inlet manifold, alternator, pass pump and associated offsetting the mass of the turbo and exhaust manifold pretty decently. I'm a bit annoyed that I'm 8KG out on the front as I'd packaged the chargecooler pump and header tank on the RHS of the nose to try and offset the mass of the chargecooler radiator in the LHS rad duct.... turns out I should have chucked it all on the same side as the steering gear, wheel, pedal box etc. makes that side heavy to start with. If I move the charge cooler pump and header tank over to the LHS I reckon I can get it within 4KG across the front axle.
What are you thinking for suspension, nice and compliant on the road but still stiff ok for a track day or are you going a bit more track orientated?
Very interested as my 21 year old shocks and springs on my Boxster s need replacing.
Very interested as my 21 year old shocks and springs on my Boxster s need replacing.
Edited by Bright Halo on Tuesday 3rd September 08:10
It's going to be a Bilstein PSS10 based kit resprung to suit the weights / balance the car has now. This also gives some ride height adjustment which allows us to get the car back to standard ride heights as it's circa 8mm up on the rear at the moment due to the lower mass between the rear axle line and the centre of balance.
This will go in on standard top mounts so should be very road friendly and compliant but still with the option to stiffen up the dampers if required for the odd track day.
On a cost / performance basis this all works out quite nicely so makes a great option for anyone else who wants to do this sort of thing
This will go in on standard top mounts so should be very road friendly and compliant but still with the option to stiffen up the dampers if required for the odd track day.
On a cost / performance basis this all works out quite nicely so makes a great option for anyone else who wants to do this sort of thing
I forgot to mention earlier that I've implemented all the soft buttons and related CANBus stuff on the CANChecked display, here's a quick video of it working:
With most of the mechanicals done I'm moving onto the systems side of things a bit more. Next up is to use the IO on the display to bring in the clutch switch, brake switch and the cruise stalk (that Mike kindly donated ).
I don't have enough IO to use all the cruise stalk switches raw so I'm going to make up a little resistor bridge (ala old school Pectel Multiplex) to act as a voltage divider so each stalk switch will then give me a different voltage. I can create a table on the dash based on the input voltage from the stalk that will the give me a value for each switch. With a bit of CAN jiggery I can then send them down to the ECU as switch inputs.
I'm aiming to be able to nudge a few settings up and down from the stalk, things like launch RPM, throttle map, maybe anti-engine brake and then have pull forward for push to pass.
With most of the mechanicals done I'm moving onto the systems side of things a bit more. Next up is to use the IO on the display to bring in the clutch switch, brake switch and the cruise stalk (that Mike kindly donated
). I don't have enough IO to use all the cruise stalk switches raw so I'm going to make up a little resistor bridge (ala old school Pectel Multiplex) to act as a voltage divider so each stalk switch will then give me a different voltage. I can create a table on the dash based on the input voltage from the stalk that will the give me a value for each switch. With a bit of CAN jiggery I can then send them down to the ECU as switch inputs.
I'm aiming to be able to nudge a few settings up and down from the stalk, things like launch RPM, throttle map, maybe anti-engine brake and then have pull forward for push to pass.
So we've designed a little multiplexer board for the cruise stalk:
Nothing says over the top like rolling your own PCB's but sod it, we needed a compact and low cost switch multiplexer anyway so there's 99 in stock now.... and one on the Booster
Center Gravity and Bilstein have also done some great work and got Booster spec PSS10 turned around PDQ!
So quickly in fact that I'm not ready to fit them yet but I'll be on that next week as soon as some top mounts turn up!
Spring rates are very close to M030 but obviously with a more capable damper inside them so this, along with the adjustability of the damper, should allow for decent suspension compliance and grip on the vast majority of surfaces whilst also being track day capable (within the limits of a sensible road car) when turned up. The ride height adjustment also means we can account for the reduced weight of the vehicle and the slight change in balance.
These are all going in with standard parts so new but OEM top mounts, drop links etc. etc. with a view to keeping the "bolt together" nature of the Booster project and borrowing as many durability tested elements from the standard road car as possible. CG will do the geometry setup so we should have a decent package together then for anyone else that is planning to build a silly Boxster!
The new bits for the engine cover are coming through, these are SLS'd from glass reinforced PA12 nylon so strong and good for over 150 degrees surface temp. They'll just be a straight bond in to the original engine cover so simple to fit.
Finally I've got a new fuel rail on the way which allows the FPR to be clocked relative to the rail, this should allow for an improvement in engine cover clearance around the FPR and is an off the shelf tuner market part so very available if anyone else wants to do the same.
I'll be taking it off the road for a few weeks to do all the above as it needs a service and a 2500 mile spanner check, it's a busy time for me at the moment but these bits pretty much complete the Booster project (bar the low ratio, LSD'd gearbox but that's a next year thing) so at that point we're just in to beating it up and having fun with it
It's been a mega project and I can't wait to put some significant miles on it. Pretty much a year from concept to "final form" and the time scales post first fire up stretched somewhat due to the production engineering required on a few bits that wasn't originaly planned..... however I'll take that for a part time program
Also a big thanks to everyone who has posted, discussed and generally been a part of this thread - it's made the whole thing an absolute pleasure to do and I apologise now that from this point there'll be limited shiny bits turning up to bolt to it..... but I hope we can keep the conversation going around the cars use (and mild abuse)
Nothing says over the top like rolling your own PCB's but sod it, we needed a compact and low cost switch multiplexer anyway so there's 99 in stock now.... and one on the Booster
Center Gravity and Bilstein have also done some great work and got Booster spec PSS10 turned around PDQ!
So quickly in fact that I'm not ready to fit them yet but I'll be on that next week as soon as some top mounts turn up!
Spring rates are very close to M030 but obviously with a more capable damper inside them so this, along with the adjustability of the damper, should allow for decent suspension compliance and grip on the vast majority of surfaces whilst also being track day capable (within the limits of a sensible road car) when turned up. The ride height adjustment also means we can account for the reduced weight of the vehicle and the slight change in balance.
These are all going in with standard parts so new but OEM top mounts, drop links etc. etc. with a view to keeping the "bolt together" nature of the Booster project and borrowing as many durability tested elements from the standard road car as possible. CG will do the geometry setup so we should have a decent package together then for anyone else that is planning to build a silly Boxster!
The new bits for the engine cover are coming through, these are SLS'd from glass reinforced PA12 nylon so strong and good for over 150 degrees surface temp. They'll just be a straight bond in to the original engine cover so simple to fit.
Finally I've got a new fuel rail on the way which allows the FPR to be clocked relative to the rail, this should allow for an improvement in engine cover clearance around the FPR and is an off the shelf tuner market part so very available if anyone else wants to do the same.
I'll be taking it off the road for a few weeks to do all the above as it needs a service and a 2500 mile spanner check, it's a busy time for me at the moment but these bits pretty much complete the Booster project (bar the low ratio, LSD'd gearbox but that's a next year thing) so at that point we're just in to beating it up and having fun with it
It's been a mega project and I can't wait to put some significant miles on it. Pretty much a year from concept to "final form" and the time scales post first fire up stretched somewhat due to the production engineering required on a few bits that wasn't originaly planned..... however I'll take that for a part time program
Also a big thanks to everyone who has posted, discussed and generally been a part of this thread - it's made the whole thing an absolute pleasure to do and I apologise now that from this point there'll be limited shiny bits turning up to bolt to it..... but I hope we can keep the conversation going around the cars use (and mild abuse)
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