Porsche Boxster 986 - engine swap project

[Escy]

Thanks. I can't take any credit for the idea. I saw people discussing it on a tuning group on Facebook and thought it would be a nice way to do it. I think it's a pretty well established technique that's been used by OEM's in the past. That said, it's something i'd never seen before.

[Escy]

So today was dyno day. I went to RRR Engineering which is near Oxford. I was up at 5am and went to pick up my mate Adam. Things didn't start off well, we stopped off for the obligatory Mcdonald's breakfast and I was surrounded by a cloud of steam, it had overheated, great start to the day. We stripped off the engine covers and did some investigation, we couldn't find any obvious leak. Thought perhaps it was just an air lock. We topped it up and thought we'd see how it was. We lost about an hour doing this. It was fine so we carried on with the journey. There was no hot air coming out the vents so there was obviously a load of air still in the system but it didn't seem to be an issue.



A video... https://youtu.be/1zPe8GyLSYA

The traffic wasn't too bad and we got there for around 10.20 rather than the 9 i'd planned on. Took this picture outside when we arrived. I like this one.



A couple of interesting things outside.





This was next door, a Arrinera Hussarya, i'd never heard of it but it's a seriously impressive bit of kit.



Bolted up on the dyno. I did take a video of it running on my action cam but it's like recording with a potato so won't bother uploading that.



It didn't take long for the problems to start, it wasn't building boost correctly, turned out it was a leak on the dump valve which was sorted out easily enough but that's something I should have noticed before coming. Then my boost solenoid wasn't working, after some investigation it turned out i'd made a wiring mistake, had used the 12v supply going to it for something else, what a prat. Again easily sorted but these issues were eating up the day as we had to let it cool down. After a few runs the car started building less boost as it got hotter. The wastegate has got a 1 bar spring in it but we were seeing 0.7. After removing the wastegate and testing it we knew that was the end of the day, it wasn't holding any pressure, stripped it down, the valve stem is all scored up and it was leaking from the base plate, the fix i'd previously done wasn't up to the heat. Got to buy another wastegate now.





It made 300bhp at the fly on 0.7bar, standard is 265 at 0.6bar. Grzes who was mapping it was great, considering all the problems which were mainly down to my mistakes he was very helpful and patient. I'm sure plenty of other mappers would have a different attitude. Considering he spent all day on it he did me a fantastic price, I was expecting to get my pants pulled down but he really liked the project and took pity on my incompetence.

Towards the end of the day the exhaust started blowing again, I think it's probably the manifold. All in all not a good day although it's not a million miles away now. To top it off, on the way home, the heaters started blowing hot again and an hour or 2 later it overheated. This time there was a stream pissing out from a hose, either a clamp not fully tight, a cracked t-piece or a hole in a hose. I used a random sandbag to help get some extra height wile investigating. So the day ended like it began with overheating.

Edited by Escy on Wednesday 14th June 00:57

[Heaveho]

Must seem like a PITA and a bit unrewarding after all the hard work and effort, but these things really are just niggles compared to what you've already been through with it. Very impressed with the progress so far. Good luck with it.

[Deerfoot]

So close now.... Can't wait to see it completed.

[8bit]

As above, it might not feel like progress to you but to us outsiders looking in it looks like you're almost there - keep up the awesome work!

[Escy]

Thanks. I've now got the finish line in sight. Since it's running decently I can get some testing miles on it before heading back for more mapping.

It drives really well so overall I'm pleased.

[Krikkit]

Good progress! Projects like this always throw up issues on mapping, simply because, as you've noted, you can't really run them much beforehand.

It all sounds relatively straight-forward to sort out though, I assume you're going to fit a wastegate with a 0.7 spring and use it for a while? Should still be pretty quick with 300hp.

[Escy]

I'll probably still use a wastegate with a 1 bar spring, I don't want the base pressure too far off what it'll eventually be running. The fuel will be off because the wastegate on it now is a massive boost leak but the ecu has a pretty good autotune function on it. The ignition and the lambda target tables are set-up now so I should be able to get the fueling reasonably decent myself although once i'm happy everything is functioning correctly i'll be going back to get it mapped again.

[Escy]

I had a look over it this weekend to see the fall out from my trip to the dyno. A boost pipe had popped off on the way back home. An EGT sensor had popped out of my exhaust manifold which was the cause of the blowing. They use a compression fitting and I obviously didn't tighten it enough. The water leak was caused by me using plastic hose joiners, they'd deformed as they got hot, don't know what I was thinking using them to be honest. All nice and simple stuff.

I ordered a new wastegate. I was recommended Forge on account of them using a piston design rather than a diaphragm and also an inconel valve. I had a look on their website and it showed one model available but looking on ebay came up with a newer model (which also has water cooling) advertised in the US. I thought that was strange so fired Forge an email. Turns out the company in the US helped test them, they haven't been released in the UK yet but they sold me one early.

I can't wait to get it fitted, that's a job for the weekend as i'll need to get the welder back out.

[wc98]

drewbagz said:

Can't wait to see this mapped and running at it's full potential.

A truly outstanding build and worthy or readers car of the year!

i will second this , great vision and determination coupled with a huge dose of ability. absolutely love it

[prof]

Hi I read the whole of this the other evening and loved every minute.

I would like to pick your brains. Do you think the audi V8 would fit if you used the A5 TDI box





the driveshafts are a lot further forwards effectively moving the engine rearwards

thanks in advance

[Escy]

wc98 said:

drewbagz said:

Can't wait to see this mapped and running at it's full potential.

A truly outstanding build and worthy or readers car of the year!

i will second this , great vision and determination coupled with a huge dose of ability. absolutely love it

Thanks, it's nice to read comments like these.

Prof, that's an interesting transaxle, not seen one before. In my opinion it won't work. I used the 987 transaxle which also has the differential further forward compared to the 986 transaxle, the limiting factor in how far forward I could mount my engine was the driveshafts fouling the suspension carriers. The problem with the V8 conversion isn't the transaxle positioning, it's the size of the inlet manifold. If you could fabricate a custom inlet manifold you might be able to limit the hacking required. I'm not entirely convinced they are worth the effort for the BHP gained. There is some recent V8 discussion on the US 986 forum http://986forum.com/forums/performance-technical-c...

[prof]

Thanks Ecsy, some great reading material on there, so it looks like the 4.2 is relatively painless if you don't mind accommodating the inlet. at <1k the 4,2s look like a better bet than trying to fix a dead boxster engine

[Escy]

The engine is cheap but they are automatic so you have the problem of the ecu and a clutch and flywheel

[prof]

the Ultima guys have the flywheel issue figured out, and if I can find the right page, hilly had a good solution on his audi V8 esprit, so shouldn't be insurmountable. i think like you found, the electrics are more of a hurdle than the physical parts

[ChocolateFrog]

It's coming on great. In the grand scheme of things these problems are just teething problems, you're 99% there.

[kev b]

Treat yourself to a vacuum bleeder for filling the coolant, best £60 you will ever spend, no more bleeding or airlocks and you can leak test the system without any coolant in.

[Escy]

I've got a cheap one but didn't get much joy using it, I think it might be leaking as I couldn't pull a vacuum on the coolant system. I don't have an air compressor so I need to borrow a mates to use it. A quick drive with the bleed valve up usually does the trick I find.

[Jens1968]

Hello Escy,

Have read your posts with a big smile. Looks very great. I'm also in a swap on my boxster. I'm working on a 4.2 swap and things are going well. Have the audi ecu figgerd out and it runs on factory ecu.(working on the subframe now) But i have now the 5 speed from a 2.7 against it. (Witch is a audi GDT unit) I also want the 6 speed. I have also a 6speed from a 986S but that won't mate up to the audi engine.

If i do a search for a six speed its getting a little bit difficult. The 987 6speed would be perfect, but is infact also an audi unit. If i google G87.20 gearbox you get very hi prices. If i google audi 01X..... i get to much hits. What numbers and codes do you have on your Gearbox?

Keep up the good work and best regards from the Netherlands. (So sorry for my poor English)
René

Edited by Jens1968 on Sunday 25th June 13:26

[B'stard Child]

Really enjoyed reading this thread on a Sunday morning - thanks for posting all the highs and lows