Knackered old Porsche with loads of natural light - Boxster!
Discussion
Couple of big bits back today....
I'm not going to start building it until next month but I might put the crank in the block just as an excuse to measure up properly and to store the crank somewhere out the way
The block has gone to 81.5mm (so first oversize basically) and the head has had some new exhaust guides, seats recut and a very, very mild skim. The crank measured up within nominal tolerance so we're pretty good all round with the big bits!
I'm not going to start building it until next month but I might put the crank in the block just as an excuse to measure up properly and to store the crank somewhere out the way
The block has gone to 81.5mm (so first oversize basically) and the head has had some new exhaust guides, seats recut and a very, very mild skim. The crank measured up within nominal tolerance so we're pretty good all round with the big bits!
Escy said:
With my engine (which isn't as tall as yours?) I couldn't have the crank centreline in the same place as the Porsche engine was, it would sit way too high so I had to lower the engine. I then lowered the gearbox to try and balance it out.
There's a nice thread here with a 2.7t swapped Boxster in the US. https://www.audizine.com/forum/showthread.php/9395...
Like me, he also had to mount the gearbox a bit lower in the chassis. If the CAD is saying it's not a problem I'm interested to see how you get on when you put it in the hole.
Interesting! On my CAD it looks like the rocker cover is essentially out the top of the bay but not by so much than the standard cover with +12MM across the back side wouldn't clear. It's close on the front edge/front of rocker cover to cover flange but not quite a clash. There's also the option of making a short rocker cover that dispenses with the seperators etc. in the standard one which I did for a previous motorsport project with this engine - again for clearance. There's a nice thread here with a 2.7t swapped Boxster in the US. https://www.audizine.com/forum/showthread.php/9395...
Like me, he also had to mount the gearbox a bit lower in the chassis. If the CAD is saying it's not a problem I'm interested to see how you get on when you put it in the hole.
Escy said:
Heat management and airflow are the biggest hurdle. Most mid engine cars have a lot more ventilation than we do. If I used mine on track I'd have been tempted to get the angle grinder out. I've got the OEM fan on one side which I have set-up to run when the car is stationary or under 10mph and the other side is open. I'm not totally convinced the side ducts actually draw much air in when the car is moving. If your whole charge cooler system sits inside the engine compartment I think it'll heat soak fairly quickly (I know that's how Porsche have done the turbocharged Boxster's/Cayman's).
My charge cooler system isn't brilliant, from the data I collect it all seems like it's working correctly but it can't cope with a decent pull at high boost, it gets overwhelmed towards the top of the rev range. Possibly the Mercedes charge coolers I use aren't a big enough surface area, maybe the coolant flow rate isn't fast enough. I guess you've got good experience with these systems so you'll probably do a better job but I feel like developing an effective charge cooler system is a massive project in it's own right. I got mine to a reasonable level, (I can have it on a lower boost and it'll do alright) and then added WMI which is like a cheat code. The car can sit on the dyno all day long and the IAT's are decent still.
You're right in that water/air heat exchangers have the potential to be a pretty deep project! When you consider it's the interaction of two thermal systems then it does make sense that it would be. I've done some work in this area previously and some recently on their use in cooling intake air in an electrically boosted H2 fuel cell system but there's still a lot of considerations that I've never gotten near. The key elements though are: My charge cooler system isn't brilliant, from the data I collect it all seems like it's working correctly but it can't cope with a decent pull at high boost, it gets overwhelmed towards the top of the rev range. Possibly the Mercedes charge coolers I use aren't a big enough surface area, maybe the coolant flow rate isn't fast enough. I guess you've got good experience with these systems so you'll probably do a better job but I feel like developing an effective charge cooler system is a massive project in it's own right. I got mine to a reasonable level, (I can have it on a lower boost and it'll do alright) and then added WMI which is like a cheat code. The car can sit on the dyno all day long and the IAT's are decent still.
- Heat exchange between the intake air mass and the coolant in the intake air heat exchanger core.
- The rate of thermal transport from the heat exchanger core
- The total amount of thermal mass in the system.
- Heat exchange between the coolant and the ambient air via the coolant system heat exchanger.
Everything becomes easier with more thermal mass in the system as that in turn reduces the rate at which you need to lose thermal to atmosphere given a fixed period of thermal addition to the system / duty cycle but then this only works if the intake air heat exchanger is capable of the level of heat exchange required to keep the air mass in the desired window in the first place. Supporting longer runs / periods of thermal addition to the system is really a case of increasing the rate of exchange to atmosphere and/or the amount of thermal mass in the system.... the flow calculation for optimium circulation is pretty easy then assuming the drops of both heat exchangers are known.
Basically it's two lots of Q=c∗p∗F∗Δ T flying in close formation with a set of flow rate calculations between...... or you just nail the largest core you possibly can in there, try to give it access to as much thermal mass as possible and then see where you end up
If you want to easilly test if it is the core or the coolant side of the system that is the problem and assuming there's a drain near your dyno it's entirely possible to plumb the charge cooler core to mains water and total loss it down the drain - that will give you infinite thermal mass at a decent flow rate so you can test the core performance in isolation.
braddo said:
On the heat extraction, might a solution be something like the inverse of a 992 GT3 bonnet? A duct on either side of the engine bay going through the rear firewall/bulkhead and up out of vents on the bootlid?
Obvs not an OEM look but a quick look at google images suggests there isn't an obvious path for lots of heat to escape the engine bay?
That is one option but any modification to the bulkheads / shell equals an immediate IVA requirement as it fails the DVLA radically modified vehicle test - one of the main targets for this is that it stays on the right side of all things DVLA and vehicle registration!Obvs not an OEM look but a quick look at google images suggests there isn't an obvious path for lots of heat to escape the engine bay?
I think extraction is okay as it falls out the bottom of the car quite effectively but getting it in is the hard bit
skwdenyer said:
The next step is to get freon in the loop to cool the water in the charge cooler circuit 
That does involve carrying some sort of air-con compressor onboard though. It's a valid option though, Tesla use an AC Refrigerant/Battery Coolant heat exchanger to cool the battery when fast charging and in ICE world the Dodge Demon uses it's HVAC to chill the chargecooler coolant exactly as you describe. 
So I've skipped ahead in the plan a bit here as there were boxes of engine stuff all over my bench and I ended up with a spare day today that I wasn't expecting.... so I built the bottom end.
Piston and rod sub assem, specified ring gaps seemed enormous to me based on past experience so I've gapped them smaller hence expect them to make a bid for freedom through the side of the block or maybe just be fine and have an acceptable oil burn rate.
New high capacity oil pump, A4 oil pickup, billet timing gear and a posh bolt and friction washer to hold it all in place.
Also test fitted the sump, mainly to stop the engine dripping assembly lube onto the floor. The original oil level sensor mounting hole has been blanked off as it's not needed in this application.
Looks a lot like half an engine now!
Also fitted the oil filter / oil cooler and breather manifold assembly.
And fitted the head studs, partly to get the box off the bench and party to keep the blue roll cover in place
Finally I unboxed and arranged all the cylinder head/valve train bits ready to build that.
Really quite impressed with the tolerances on the pistons and rods. With a bit of mix and matching I was able to get all the clearances within a "blonde one" of each other and in the good bit of VAG spec.
Productive day all round really!
Piston and rod sub assem, specified ring gaps seemed enormous to me based on past experience so I've gapped them smaller hence expect them to make a bid for freedom through the side of the block or maybe just be fine and have an acceptable oil burn rate.
New high capacity oil pump, A4 oil pickup, billet timing gear and a posh bolt and friction washer to hold it all in place.
Also test fitted the sump, mainly to stop the engine dripping assembly lube onto the floor. The original oil level sensor mounting hole has been blanked off as it's not needed in this application.
Looks a lot like half an engine now!
Also fitted the oil filter / oil cooler and breather manifold assembly.
And fitted the head studs, partly to get the box off the bench and party to keep the blue roll cover in place
Finally I unboxed and arranged all the cylinder head/valve train bits ready to build that.
Really quite impressed with the tolerances on the pistons and rods. With a bit of mix and matching I was able to get all the clearances within a "blonde one" of each other and in the good bit of VAG spec.
Productive day all round really!
Edited by poppopbangbang on Sunday 24th September 22:44
Mikeeb said:
What ring gaps were they recommending?
Gap factor of 0.0080 per inch of bore for the top ring which in proper measurements works out at 0.65MM. The pistons are made from a pretty sensible alloy which by my maths (and given the pistons are cooled by oil squirters) shouldn't need much more than 0.45mm.... so I went in the middle.
not seen one of those for a while!
Dr.Hellno said:
Those Venoms are flippin mental!!
You not interested in water/meth?
It'll have water/meth for the higher boost / sustained boost scenarios (it's rude not to!) but the charge cooler system will also have around 5L of coolant in circulation which is quite a bit of thermal mass on its own.You not interested in water/meth?
Few more bits done this evening, the bottom end pretty much done and just waiting for the head to go on!
Stock head gasket because MLM.
Water pump and belt tensioner on.
Oil cooler, breather and turbo oil feed fitted.
Quite a few AN Banjos appearing on this! I want all the lines to look as OE as possible so these will be boggo braided with crimped steel fittings like the standard ones. They might not look as flash as an anodised AN fitting but they're bomb proof and last forever (see JCB )
Made half a turbo oil return line.
All the valves are in so tomorrow I get the fantastically enjoyable job of trying to get the keepers in.
Still waiting on a few bits so this isn't going to be done and done any time soon but the vast majority of parts are now contained on the engine stand which means the workshop looks a bit tidier and my OCD is less tweaked
Stock head gasket because MLM.
Water pump and belt tensioner on.
Oil cooler, breather and turbo oil feed fitted.
Quite a few AN Banjos appearing on this! I want all the lines to look as OE as possible so these will be boggo braided with crimped steel fittings like the standard ones. They might not look as flash as an anodised AN fitting but they're bomb proof and last forever (see JCB
)Made half a turbo oil return line.
All the valves are in so tomorrow I get the fantastically enjoyable job of trying to get the keepers in.
Still waiting on a few bits so this isn't going to be done and done any time soon but the vast majority of parts are now contained on the engine stand which means the workshop looks a bit tidier and my OCD is less tweaked
TV8 said:
What a great project. I have been on Pistonheads a while but mostly in the TVR section and this readers car bit is new to me. Discovered after the Bicester event. I need to write up one for my Boxster to balance it out a bit at the skill level. Latest entry would be, took out seat to replace clutch pedal spring. Gave up and put seat back in!
Looking forward to seeing what happens here.
To be fair, the clutch feel is much better without the spring Looking forward to seeing what happens here.
Bit of an update
The motor is getting on for being done bar waiting on some bits so I can fit the cams.
Once those bits are here I can fit the cams and pulley, fit the belt, put the covers on and bolt the ancils back on (just a PAS pump and Alternator required!)
However a few bits in the pics are very much place holder. Top mount turbo is clearly a no go so the current manifold is going in the bin to be replaced with something that will position the turbo a little more sensibly - I've got a couple of options inbound to try, one is a simple cast one which is probably the best idea and one is a 321 tubular stainless one that is likely to do nothing but crack around the welds but looks amazing so lets see how that works out!
I also need to change the inlet manifold for an AEB one as that has larger runners which match the AGU cylinder head, I still need to find one of these!
Finally the rocker cover needs to be swapped to get the engine height down, the common version with an oil seperator/breather in the top is really a no go due to clearance and breather routing. A longitudinal version solves the breather but still retains the height so I've managed to track down a NOS 1997 A4 version which had no breather:
This coupled with no VVT solenoid hanging out the end means (according to the CAD!) it sneaks into the bay an absolute treat. I would like some cam cover breathing though so I'm going to weld an AN10 into it on the inlet side and breathe it that way back into the inlet. It also adds some additional complexity in that R8 coils don't fit that cover so I'll either have to draw up some adaptors or buy some.
I've got a bit of a decision to make on engine mountings as well, the original pass the boost pipe through the mount is 1) Super Cool and 2) Really super expensive to machine! I've cadded up an alternative using 60mm boost pipes from turbo to chargecooler which is WAY cheaper to produce and the reduction in pre cooler boost pipe size makes no real difference to things so this may be the way to go..... especially as it seems a couple of other people would like to buy some bits to do this at some point.
I'd say that was still fairly tidy as these things go
All said I'm well on target for my timescales, the engine should be done by end of the month, CAD is complete I just need to decide which version I'm going to make and the machining of various bits is good for November..... which is good because if i can't get this in over Xmas break I'm going to be stuck for a while
The motor is getting on for being done bar waiting on some bits so I can fit the cams.
Once those bits are here I can fit the cams and pulley, fit the belt, put the covers on and bolt the ancils back on (just a PAS pump and Alternator required!)
However a few bits in the pics are very much place holder. Top mount turbo is clearly a no go so the current manifold is going in the bin to be replaced with something that will position the turbo a little more sensibly - I've got a couple of options inbound to try, one is a simple cast one which is probably the best idea and one is a 321 tubular stainless one that is likely to do nothing but crack around the welds but looks amazing so lets see how that works out!
I also need to change the inlet manifold for an AEB one as that has larger runners which match the AGU cylinder head, I still need to find one of these!
Finally the rocker cover needs to be swapped to get the engine height down, the common version with an oil seperator/breather in the top is really a no go due to clearance and breather routing. A longitudinal version solves the breather but still retains the height so I've managed to track down a NOS 1997 A4 version which had no breather:
This coupled with no VVT solenoid hanging out the end means (according to the CAD!) it sneaks into the bay an absolute treat. I would like some cam cover breathing though so I'm going to weld an AN10 into it on the inlet side and breathe it that way back into the inlet. It also adds some additional complexity in that R8 coils don't fit that cover so I'll either have to draw up some adaptors or buy some.
I've got a bit of a decision to make on engine mountings as well, the original pass the boost pipe through the mount is 1) Super Cool and 2) Really super expensive to machine!
I've cadded up an alternative using 60mm boost pipes from turbo to chargecooler which is WAY cheaper to produce and the reduction in pre cooler boost pipe size makes no real difference to things so this may be the way to go..... especially as it seems a couple of other people would like to buy some bits to do this at some point. I'd say that was still fairly tidy as these things go
All said I'm well on target for my timescales, the engine should be done by end of the month, CAD is complete I just need to decide which version I'm going to make and the machining of various bits is good for November..... which is good because if i can't get this in over Xmas break I'm going to be stuck for a while
Couple more very quick bits done this evening:
Ancils on, just waiting on a tensioner and a belt now, hopefully measured the required belt length without the air con compressor correctly!
And the new (to this project) fuel rail, from an early 20V Passat that puts the feed and return in the centre of the rail - the original was a clash with the engine bay upper surface.
Little by little!
Ancils on, just waiting on a tensioner and a belt now, hopefully measured the required belt length without the air con compressor correctly!
And the new (to this project) fuel rail, from an early 20V Passat that puts the feed and return in the centre of the rail - the original was a clash with the engine bay upper surface.
Little by little!
It'll be sub 1250KG, quite how much I am not sure until a few bits are machined up and I've been able to weigh the clutch etc. but I'd guess circa 1230KG when complete. This build isn't focused on lightweighting the car as much as bolting in lots of power but if really wanted to go all out then I think you could get one down to low 1100's with the carbon front end from my 996, no roof, light wheels, single silencer exhaust and some sound deadening removal.
Gassing Station | Readers' Cars | Top of Page | What's New | My Stuff