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MaxDiesel

New mid engined aircooled project...

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15 hours ago, MaxDiesel said:

¬†So far I've found nothing wrong with existing P&C to use as an excuse to replace them¬†ūüôĀ¬†

Yes you have - There's that ding in the piston where the valve went into it. That will never be the same again. Safest to replace and while you're in there...... ;)

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Excellent work as usual Matt!  

"Beasley makes it look easy" that's a new reality TV show or sitcom right there.

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As Rb says there's no replacement for displacement  , but not my wallet ! 

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12 hours ago, flatsix777 said:

Great work Matt. I thought about this myself and although I didn’t do a lot of research I did establish that the ECU & injectors for the 1.7 have different part numbers relative to the later 2.0L This makes me think that some changes might be needed here to get the benefit of a small capacity increase. I think if I did this I’d go bigger still and address fuelling properly otherwise stay original. 

Getting the benefit of high octane fuel is a great idea. Aside from compression & port matching I think there may be gains by optimising ignition timing. I’ve been looking at the 123tune distributor as an easy way of customising the curve. I’ve just helped a friend fit a blue tooth enabled 123 to a 3.4 Mk1 Jag & it’s a great piece of kit and very easy to work with. Not cheap though. 

That hell hole looks quite bad, no doubt like most 914’s. I hope it’s not too extensive when you get in there but it’ll be worth the effort for sure. 

Cheers

David 

I'd spotted the 123 ignition kit - they do one specifically for the Type 4 engines with the injection pulse trigger built in. A colleague of mine has one fitted o his highly tuned Midget and says it works very well with all the other mods he's got.

I've seen some guys in the US have managed to get D-jet injection to work with bigger capacities - they've done this by adjusting the fuel pressure regulator and manifold pressure sensor - which I guess makes sense. It'll mean either fitting a Lambda kit or spending some time on a rolling road.

Fortunately the rust seems localised to the hell hole and a bit on the jack points - the  floors are completely solid unlike others I'd looked at. I'll be taking a deep breadth and cutting back until I get to something solid - going to need to practice my welding as its been a few years!

12 hours ago, SilverWT said:

Sure you already know this, when Porsche went to 2L they made new heads for the 914 application (bigger valves, ports and changed combustion chamber shape). They used a different 3 stud inlet manifold and different ECU etc.

VW stuck with the same designs as the 1.7 & 1.8 heads for their 2.0 van application (although VW varied valve sizes, bigger in the 1.8, smaller in the 2.0 from memory).

Mark

I was aware the 2.0l head had bigger valves - I hadn't realised they changed to 3 stud inlet flange - I guess this means 2.0 heads must have 2.0 inlet manifolds which I'd want to avoid.

9 hours ago, Richard Bernau said:

I would go big on capacity.  If someone values originality, how will they ever really know its not original and in the meantime you have the fun of a bigger torque motor which I think would make a real difference.  A long time ago back in NZ, I spent some time driving around in a 69 912 (Hamish's first Porsche), so I have a vague idea of the experience of this kind of powerplant.  Its fun, but no getting away from the fact its slow.

I used to have a '68 912 many years ago and it was pretty sedate. I ended up rebuilding this as a fully balanced high compression 1720 with mild cam and Weber 44IDFs - this reliably gave ~115hp which was enough to make it fun as it didn't weight as much as a 911.

They other thing the makes the 1911cc kit tempting is the price - less than a tenth of the cost of the Mahle 3.4 P&C on my 911!

Think I might get stuck into the hell hole rust next and depending on how that goes make the call on bigger P&C.

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Looking good Max, I've ways fancied a a 914 6. The closest I've come to a type 4 engine is my type 3 vw square back variant. I rebuilt it to 2l fitted a fruity cam and some webers doesn't half go now.

There's loads of options on the type 4 base . You can build a serious push rod engine for a fraction of the cost of a 911 one. DBS

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Bit more progress on the engine this weekend - had a closer look at the bores and the rust marks & pitting from when it stood for many years is worse than I originally thought:

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I think this is the excuse I was looking for to go for the 1911cc kit ūüôā

Spent a tedious couple of hours degreasing and pressure washing all the tinware - can't get over just how much there is on a type 4 engine. This lot is off for blasting and powder coating next:

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Due to the rust marks on the bores and likely increase in bore size I thought I better pay it safe and check the bottom end too..... 

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All seems fine apart from loads of black sludge in sump. More degreasing and pressure washing...

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Crank journals look fine

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There's a place nearby that  does vapour blasting - I'm going to see how much they want to the the heads and case halves

Edited by MaxDiesel

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you're not hanging about with this build

never liked the 914 until I had a ride in one, would love one, it felt like a go-kart

why stop at 1911cc, is there a big jump in price above this capacity?

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20 minutes ago, World Citizen said:

why stop at 1911cc, is there a big jump in price above this capacity?

Probably requires a stroker crank.

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On 1/13/2019 at 11:21 PM, World Citizen said:

why stop at 1911cc, is there a big jump in price above this capacity?

Tempting... but my aim is to keep the engine bay looking original - so I'm sticking with the 1.7 D-jet injection - which I'm sure would seriously limit the benefit from going any bigger.

I dropped the crankcases off at this place for vapour blasting (http://cbxvapourblasting.co.uk/) - its going to be interesting to see how they turn out. The guy had a impressive mix of classic bike and car bits in for cleaning - the finished stuff looked great.

Into the measuring and checking phase now. Started by cc'ing the heads

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Then worked out the piston dome volume by setting the piston a fixed height down the bore and subtracting this volume to get the dome cc

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This all confirmed the CR was just over the 8.2:1 in the spec book. The 1911 kit has flat top pistons and I think the same compression height - with the new bore size plugged into my spreadsheet I get ~9.3:1 so I'm still going need to tweak the head volumes to get to my target 9.5:1 - this can be done when they're machined for the large bores.

Also finished stripping the crank - got the gears pulled off and rods off - all looks to be in good condition:

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Journals look like new - just need to borrow a micrometer and double check diameters

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Time to start ordering some new bits ūüôā

 

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Seems like you are getting stuck into this - thanks for posting updates and pics.

12 minutes ago, MaxDiesel said:

I dropped the crankcases off at this place for vapour blasting (http://cbxvapourblasting.co.uk/) - its going to be interesting to see how they turn out. The guy had a impressive mix of classic bike and car bits in for cleaning - the finished stuff looked great.

You probably already have done but make sure you are very specific about what you want done. Sometimes blasting places will grit blast first to get rid of the heavy stuff then finish with vapour which can sometimes lead to a less than favourable results. They often do this is good faith (or lack of customer prefs) thinking you want stuff super clean no matter what and because vapour only can be time consuming and expensive in terms of energy used they sometimes hit it with grit which can damage parts that you would have preferred to had finish at home.

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*edit just read some more details from the guys you are using, they seem to be on top of their game but will leave my comment in place for future refs.

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13 minutes ago, jevvy said:

*edit just read some more details from the guys you are using, they seem to be on top of their game but will leave my comment in place for future refs.

Cheers Jevvy - I was a little sceptical myself but the guy at CBX seems to know his stuff and was happy talk me through exactly how he'd do the cleaning - definitely vapour only which explains why is not cheap...

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