Porsche 911UK Forum

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

3.9 Engine Build

Yes it is printed abs Matt, the finish is a little grainy but that's one of the limitations and the part doesn't need to look really pretty (function over form....)

It could probably be metal printed too (though not looked into this and I expect would be much more expensive).

Congrats on your engine's re-birth, been following your thread.

:thumb:
 
I think you might struggle with ABS, I did. The problem is two fold, with the GT3 throttle body you can't effectively support the body off the top of the PAS pump like it is as standard so the entire weight of the body, intake hose etc. is hanging off it which then causes the plenum to fail around the throttle body flange. Secondly ABS isn't that stable so with the ambient temp in the bay at around 60 degrees I found the clamping load of the bolts pulled the flange over time which then caused and air leak.

This was the final version I arrived at:



You can see I essentially deleted the flange and extended the bolt "holes" back along the piece to add strength and remove the step of the flange. I also added additional webbing and chamfers to reduce the stress risers at the transitions and increase overall strength.

We printed this in carbon reinforced nylon with stainless thread-serts printed in. It pretty much worked but again the stresses on it from it supporting everything from the plenums up were a bit too much for me to be comfortable with - plus printing carbon reinforced nylon is a bastard and the nozzles on our kit are REALLY expensive :hand: so as it was taking one nozzle to print one plenum I didn't really want to do it again if it did fail. In the end I just ordered an IPD one as it was cheaper than machining one from solid.

It might be worth speak to 3D Systems advance prototype division as they offer epoxy resin printing which would be strong enough. Failing that maybe some way of additionally bracing it externally off the bottom two throttle body mounting bolts?

If you want a copy of my CAD let me know and I will send it over. All the best with it - it would be great to see someone succeed when I gave up and took the easy option :thumb:
 
Matt

Thanks for your feedback and findings, very useful :thumb:

My route has been to stick very close to the oem one with subtle changes. My plan is to support this off the pas housing bolts, that will require fashioning of a bracket, two places would be better than one.

There are some nice barbed brass inserts that I've seen which I will trial (probably inserted with an expoxy resin) to hold The TB to the plenum. And nothing more than a nip up of the bolts should be required, this uses a rubber o ring for sealing.

Did you consider having it 3D printed but in metal?

I'll drop you a PM.

Cheers
Harv


:thumb:
 
Hi Harv, very interested in how you get on with this and also wondering if you knew of a larger throttle body option for those of us with a cable actuated throttle?
 
Following on from checking installed piston heights we had .012mm above the cylinder deck which although gave clearance once the head gasket was installed was too tight. To properly determine chamber cc the piston top was greased, and the head (with valves) bolted down and chamber filled through the spark plug hole (taking into account CC's displaced once spark plug is installed), this provided data to establish that the cylinder volume was too small at around 58cc.

Pistons removed and sent out for modification (thanks Baz) and now we have proper chamber specs, decent piston top to head clearance and a slightly increased compression ratio from OEM.

So on with the bottom end build up.



Lots more cleaning for the other case half and ready to bolt up, case sealant and new water channel gaskets



Cases together and torqued down, sump items bolted in



Installing Pistons 4-6 into bank 2 requires working through a small hole to fit the gudgeon pin retaining clips. This wasn't as bad as I feared thanks to a cheap endoscope camera and Infrasilvers install tool

Crank rotated and piston 6 goes in first



Aligning piston and rod through the access hole



Pin and circlip fitted and confirmation it's correctly seated



Same for piston 5



And piston 4 which seems easy after the other two!



More soon


:thumb:
 
Amazing work here! Wish I was capable of doing this sort of upgrade. Be really interested to hear about the performance difference when rebuild completed. I read that Hartech were trialling 3.7 and 3.9 upgrades. But have not seen any bhp, or torque figures yet. :worship:
 
Thanks

Not sure about performance figures but will post up once we know. This has progressed quite naturally from needing to address oval bores/oil consumption and burnt valves to where we are today so any hikes in power will be a bonus.

Waiting for a complete set of new timing chain guides and some head bolts, then we can complete the build.
 
Great stuff Harv looking forward to seeing how it performs. Are you noticing any recent price hikes from Porsche?
I went in to collect a few bit today and they gave me a quote of €2205.40 for a set of hydraulic lifter. I thought this seemed a bit steep. (996C2 3.4l).
 
ELA said:
Great stuff Harv looking forward to seeing how it performs. Are you noticing any recent price hikes from Porsche?
I went in to collect a few bit today and they gave me a quote of €2205.40 for a set of hydraulic lifter. I thought this seemed a bit steep. (996C2 3.4l).


£40 ish each just over £1000 for a full set of 24 for a 3.4 from Design911 in the UK and their price guide is the same as OPC for genuine parts usually, get them shipped from here.

The 3.6 variocam plus inlet tappets are more expensive when I had to replace some, (over £100 each) but would still be nowhere near £2000 for a full set of inlet and exhaust.
 
If find the OPC is expensive but cheaper than D911 and the like and we have a good rep with the head parts guy at Mid Sussex.

Richard that's eye watering, I remember it was steep when I inquired but whoah.

The same spec of lifter is used in some BMW's etc (INA make springs to mind) and though I was dubious ordered up 12 to replace my exhausts ones as a precaution having suffered exhaust valve failure. I've had a micrometer on them and they are identical in every way, o/d, height, weight, internal contact bucket and oil gallery channel so I will be running them. As a set these were £80 or something like that delivered.

The magic part number is HL6330

Chris do you know how to test the variocam plus inlet tappets? I'm giving mine a good soak in an ultrasonic bath and then will reuse them unless testing shows any issues.

:thumb:
 
I thought it seemed a bit steep.
The inlet ones were more than double the price of the exhaust side. If they are £80 a set for the exhaust, is there any chance I can pay you and you order me a set or give me the contact details and the invoice number so that I can ask them for to repeat the order and send to me. Also I just checked D911 and they only list the exhaust tappets. Do you know where you can buy the inlet ones for a reasonable price. You mention you ordered up the exhaust side. Is this because they are a known weak point? I've just fitted a new Crankcase Tensioner today and this hasn't rectified a tapping noise I had. I did another check today and it appears to be coming for the No.3 cylinder. So I'm thinking most likely now is a tappet from that cylinder; whilst in there I may as well replace the lot if they are only £80 a set :thumb:
I'll just do one more check in the morning first, to make sure it isn't just a lose spark plug...
 
I'm undecided about my inlet ones ATM because I have variocam plus on the 3.6 which uses 12 solid exhaust lifter and 12 split type for the inlets and I cannot find any alternative for the inlets and believe they are unique to this engine.

Mine came from Germany (made there) but I don't recall the seller.

Try here as these are all the same, you'll of course need 24 assuming you have a 3.4

https://m.ebay.de/sch/i.html?_from=R40&_trksid=m4084.l1313&_nkw=HL6330

One thing to mention, check the lifter carrier bores for each bank where these sit for ovality at the 12-6 and 3-9 positions. No limit spec exists but take note that if it's significant then new carriers probably are required.
 
Harv said:
I'm undecided about my inlet ones ATM because I have variocam plus on the 3.6 which uses 12 solid exhaust lifter and 12 split type for the inlets and I cannot find any alternative for the inlets and believe they are unique to this engine.

I randomly found out today the 3.6 inlet tappets are exactly the same as the Subaru ones, not sure on pricing but they are apparently a Porsche part number, Subaru liked the design for their Boxer. If they are cheaper I will be surprised but you never know, is Subaru tax cheaper than Porsche tax :dont know:

Harv said:
Chris do you know how to test the variocam plus inlet tappets? I'm giving mine a good soak in an ultrasonic bath and then will reuse them unless testing shows any issues.

Other than checking for binding I kept my inlet tappets soaked in oil once they were removed and the new ones straight into oil for a few weeks until I fitted them, nothing more, they did rattle a little (they all did most probably) until I got the engine really hot and then the noise cleared.

They should go back into the same position they came from as they are set at the factory as with a lot of things, I replaced some of mine for new ones and they just went in wherever I put them and were fine as you would expect.
 

New Threads

Forum statistics

Threads
124,350
Messages
1,439,419
Members
48,707
Latest member
race911turbo
Back
Top