Whoa - I have a 2.7L. Now what?

[Tdskip]

Good morning, first and foremost I hope everybody is doing OK and healthy.

This is going to be a bit of a long introduction, but I want to make sure I give the information that you are likely to to ask for. About two years ago I bought a Porsche 914 they had a really interesting engine build but no documentation attached to it. This car was built for auto crossing or time attack events and had some sort of unique heads on non-factory pistons. It also had a pretty good side turbo and custom exhaust. The turbo had been disabled when I got it via the wastegate, and without any documentation or real history on it I assumed it was best to leave the turbo bypassed so that’s what I did.

I ran it for a little bit and it felt really torquey but never ran right. I didn’t run it a whole lot because once hot it had fairly marginal oil pressure and I didn’t wanna further damage anything, but on the drives that I did on the highway it would run at 80 miles an hour very comfortably and my oil temperature and cylinder head temperatures were always well within what’s considered normal. The car has a front mounted good sized oil cooler and braided lines running from the engine compartment to the front of the car, no other cooling modifications and no upright conversion.

I ended up dropping the engine and putting a stock 2 L 914 engine back in and pushed this engine to a corner of the garage. With the current slow down I took the opportunity to start digging into the engine and discovered that it’s much more built than I had initially realized. Now that I’ve taken the top and off I am looking for some ideas and coaching on what to do from here.

When I started disassembling the engine I found that both the bolts on the rocker shaft four cylinder number three had backed off there by disabling that cylinder from doing anything. It doesn’t look like anything was damaged but that was a bit shocked to see it because the engine felt pretty darn strong even though it was apparently only running on three cylinders for sometime.

What I discovered in tearing the engine apart is that it has TRW flattop pistons and the barrels are aluminum with a steel sleeve. The barrels still have their crosshatching and I don’t see any nicks or scrapes, the Pistons need cleaning but don’t see any marks on them either. I have not split the case yet, but the connecting rods and what I can see when I look inside it all looks new / clean. The engine oil, wall free of any metal, did get dirty pretty quickly and as I mentioned when hot the oil pressure at Idol was unacceptably low.

The case was modified so it has six stud ls now, and I have a 103 bore with an 82 stroke, if I do my math right that equates to a 2.7L build!

All of this leads to three questions;

1) what now?
2) how to do it right?
3) If I rebuild it how do I make it last?

i’ve tried to educate myself even though this is my first time dealing with a Type 4 build;

1) because I have low oil pressure I don’t think I have an option but just with the case and figure out why. Correct?

2) Once the case is split I should probably have a machine shop check it and do any remedial work? A good shop should be able to make sure the boys are OK and the case is straight and inspect the crank as well as help me get the right combination of bearings – right?

3) it appears that heat management and not over stressing the barrels are the key issues when dealing with big bore builds from what I have read. I already have a oil cooling system that appears to have worked to keep the car cool, what airflow management option should I be considering here? I am not going to race this car, mostly I use my vintage cars for spirited touring events and family roadtrip through interesting parts of California and Oregon. That means a mix of open highway and flowing roads through the canyons where the car is being run through the gears but not any sort of extreme driving conditions or beating the stuffing out of it.

I know this won’t have 100,000 mile sort of typical longevity, but do you think I can get 30 to 50,000 miles out of it?

Thanks to all those that read this, again I apologize for the long post but it seemed better to just give the background right away.

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[MegaRookie]

To start, thats really an interesting engine you have there. Must be nice to drive, even on 3 cyls :O

As you mention, i would tear it completely down and have everything measured and rebuild it with new bearings if needed to solve the oil pressure problem. If you cannot do the measurements etc. yourselve I should ask an expert.

I am not living close, so I cannot recommend one, but I am sure you will find one.

Please keep us posted on the build, and if you have some more pictures of the 5th and 6th stud (how connected to the case and heads) please share them! I am very sure that more people (besides myself) are interested in those details.

Good luck on the rebuild!

Best regards Mark

[Tdskip]

Good day Mark, thank you for the response. Hope you are well.

I will get those pictures of the studs posted shortly.

I will keep going on the tear down and post pictures of anything interesting.

Edit - inside looks pretty clean. The person who built this used RTV by the gallon!

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[GARRICK.CLARK1]

The clearance work on that big end cap looks a bit extreme. Maybe that's how it is for an 82 crank

[Tdskip]

Hi Garrick - thanks for the note. I don’t have a pontoon reference to compare it to, what caught your eye?

Thanks.

Here is a picture of the 6 stud set up.

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[GARRICK.CLARK1]

The con rod cap bolt has been shaved in the pic were you mentioned the RTV by the gallon

[GARRICK.CLARK1]

Its took some time to do that 5th and 6th stud conversion.

[H2OSB]

Wow, so it was initially a 2.7 Turbo? Man that would almost be scary in a 914 because they're so low(like a giant engine gokart). That said, it's a very good chassis to have that much power in.

Have you calculated the CR? Was it running carbs or FI? Sounds like you lucked into a nice starting point.

H2OSB

[Tdskip]

Hi gentlemen, hope everyone had a god Saturday all things considered.

@H20SB, yes it is a 2.7L that also had a large turbo on it. Must have been a lot of power =- when it ran. The 914 it was in was/is pretty build to handle the power. It did shred the clutch that was on it - likely when the turbo kicked in.

It was running a single giant Weber with fuel enrichment based on vacuum, oil lines to the turbo etc as well.

I need to measure the heads to get the CC still, hopefully next couple of days. Wondering how low they kept it knowing it was going to have boost.

I'm going to keep going, I expect the internals to be decent based on how much was spent on everything else and I don't think it had many hours on it.

I think the big issue, assuming I continue to get lucky on what I find, is how to keep it cool once it is back together.

[wreck]

I've never played with a boosted engine but with research I've done I'd plan on as big an intercooler that you can fit and water meth injection . Also fuel injection is also desirable . I'll get the rods looked at and particularly the rod bolts . If you haven't down it already "Wally's" thread on turbo type 4's on the boosted forum and the Engine Builds thread on this forum are a wealth of information .

[GARRICK.CLARK1]

Can you keep the strip down pics coming. I'm interested in what's been done inside the case. I'm sure others on here wanna see it too.

[twodollardoug]

Are you going to keep it turboed? Or go naturally aspirated?

[Clatter]

What a killer motor!

Imagine driving on boost..!

That was definitely somebody's baby back in the day.
Much love was put into that thing.

Please post more pics, it's great to see these things.

Here's what I'll add (FWIW)

It used to be SOP to lighten factory rids like that.
A TON of work, but the factory rods even lightened up are actually very strong.
Looks like they were shot-peened too.
Wouldn't be surprised if they have some nice bolts as well.
You'll need to identify what kind they are, likely ARP or SPS.
You'll need to acquire a way of measuring bolt stretch, and see what they stretch to at what torque to see if any have failed.
Real motor shops of any kind do this all the time FWIW.
If the bolts are stretched, they sell ARP bolts at Summit or Jegs.

You'll also need to get the heads surfaced.
Doing so on a motor like this is careful business.
Most shops don't have the correct tooling for odd sizes like this.

Absolutely love those chambers!
Can't remember what that 'squish groove' by the plug is called, it has a name.
Also how they dimpled by the intake valve to promote atomization (detonation? )..

Torque on the two extra head studs is a topic of discussion.
They almost look like they might have been done by FAT?

I'd be inquiring with Jorge at EMW and also with FAT (now FAT/Rimco) to see if they wouldn't touch this stuff for you.
Don't be surprised if they can't find their ten-foot-pole handy.

You'll want to be thinking long and hard about engine management, and how to approach this.
Obviously, it wasn't working as a turbo motor when you got it; for a good reason I'm sure.

With modern engine management (spark and fuel) you can tune a motor like this to make good power and live with some real boost.
Knock sensing, intercooling, water/meth etc. will be required to get the most out of it.
Man, it would be a beast..

You could also go and rock it old-school, too.
Just get it tight and throw it all back together.
Jet it fat, keep the boost low, don't expect a long life, and have fun.. That's all good too.

So go ahead and tear it clear down,
And post up a bunch of pics.
I'd love to see inside that thing,
And some good overall shots of how it was packaged and all.

Killer, Killer motor. Love it!

[Tdskip]

Are you going to keep it turboed? Or go naturally aspirated?

Good morning - I'm thinking naturally aspirated so It has a longer lifespan. By longer I mean lifespan likely measured in weeks not days... Ha.

[Tdskip]

Did some more digging this morning (busy with other things, sorry, updates may be slow).

Intake valve is +/-50mm, exhaust is +/-40mm.

@clatter - you nailed it first on those dimples, good eyes. Combustion chamber dimples were put there to improve intake flow / mixture? That is what the 914 forum guys suggested.

I am assuming the nicks circled in blue are not good...

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