Tubo charged T4 for a 1966 Porsche 912 - need advise

[Rickster]

But the problem is that the Subaru pistons "May" have skirts that would interfere with a 76mm stroke (per your earlier warning)? I simply have no way to confirm that without parts in hand. I think you recommended looking into the 2.2L Suby pistons, but those are all 97-98mm bore sizes.

And for the Toyota pistons, I can only seem to find a very limited number of these coming back from my searches. (And I would have to go with an aftermarket rod and move to a 94mm cylinder)

I can get the Suby 2.0L pistons to work on paper:
Deck Height : 202.5mm
Stroke: 76mm
Rod Length: 131mm (RIMCO "Super Rods" per you suggestion)
Compression Height: 32.66mm (Weisco K588M93AP | -9cc dish)
Rod Ratio: 1.72 to 1
Deck Clearance: 0.84mm

If I assume a head combustion chamber of approximately 57cc after porting, bigger valves, etc...
This leaves a very workable 8.2:1 compression ratio, and gives me room to add a thin shim if I need to bump it down a scootch...

Also, there are a LOT of different CH and dish volumes available to work with in either direction.

I really get everything I want, but your previous comment just worries me now about possible skirt to crank interference with the 2.0L Suby pistons (I'm probably way over thinking this )

Thanks again for the sanity checks, suggestions and putting up with all the endless noobish questions

Rick

[Piledriver]

My bad... Subaru had a few bore/stroke combos over the years.
2.0L EJ20T Subaru pistons are 92mm std/stock.
2.2L for a 2.0 crank ..~97mm

2.5L pistons are 99mm.

The subaru 2.0 or 2.2 has a 75mm stroke and 130mm rods, but a pretty short deck height of 201mm, and no way to jack it up with longer cylinders or spacers as an ACVW setup can.

It has pretty short skirts by definition.
Stroker versions will be even shorter.
Get a used $10 stocker and have at it with a die grinder to see what is needed.
Order custom if you have to, but I doubt it.
Look at some on Ebay--- There's almost nothing below the pin boss.

The bus pistons I was referring to earlier have quite long skirts, and are made for a 71mm stroke crank.
They are a PITA to clearance for 76mm. but you are not going up quite that much, and with a (1mm) longer rod.
They also have a totally wrong compression height but can be shaved down a long way due to a deep set top ring and solid "ring" of piston above it.

Pick the right compression height...and crank. 78mm works with that combo, and costs NO more.
You may need to do some clearancing building any stroker motor.

Target .040-.050" deck, .060 absolute max on a very high revving engine with 4" bore.
I have run down t .024" and taken it to the rev limiter on every on ramp in every gear for hundreds of thousands of miles on a 1700... No contact. No carbon buildup either.
.080 deck is ~zero squish, is in la-la land and will actually make it far more prone to knock.

You should still run the numbers on some of the other stroke/rod combos, the good/cheap chevy or t1 journal rods DO have much better rod bearings available.
A t1 rod big end will require a lot of case clearancing and probably a reduced base circle cam, unless the rods are really thin on the big end.

A 93 x 76 with the "porsche" length rod in chevy journal should just about work out, but will need 22mm pins like stroker 22R slugs or full custom in subaru pistons.
Might need a cylinder spacer.

You want easy, build a stocker or very close.
Once you start getting weird there's a lot of possibilities and potential issues to deal with.

[Rickster]

Just an update after a long break to finish up my AC Cobra build and other stuff...

A recap for those not wanting to re-read the entire thread. I was looking for options/advice for a turbo charged 1800 T4 I had sitting in my garage.

=========

I just found these recently, looks like they would just drop right in...?

Weisco KE221M93 (93mm) or KE221M92 (92mm)
Comp Height: 41.9mm
Pin Dia: 24mm
The correct 4032 alloy recommended by Pile above
Flat top (8.3 static comp w/ 55cc 1800cc heads) Perfect for my turbo build!???

The deck height is almost perfect at 0.9mm (0.035") in the hole...right inside the "squish" zone outlined by Pile

$550 for Pistons pins and rings...

Search:
Pinto 2.0 1971-1974 Forged Pistons, for other manufacturers.

Rick

[Clatter]

I just read this again.

Thought i'd throw a few (rudimentary) thoughts out there, because you come from another school.
Please don't be insulted if what I say is painfully obvious..

Don't discount shortening cylinders - if you have a lathe and some skill, it costs even less than shims.
Or beer and a friend with a lathe...

Don't worry about the skirts clearing the crank - you might use a die-grinder to balance the pistons anyway, right?
IME, only stock pistons seem to need skirt clearancing with a 76, or even 78 crank.

Don't discount other rod journals to get you more rod options.
Many like the Type 1 rods to get more piston options.
Or Chevy/Buick, 912, or..?
Once you order up a crank to be made, you can pick your journal - and then rods.

While Pile may say that H-beams get you nothing under 7K,
Light and cheap always gets you something..
Both ends of stock rods are heavy !

That said, mucho has been done with stock/mild lower end parts.
Stroker _And_ turbo for your first build is insane.
Few such things exist.

If you can beat this guy with your stock 66-stroke motor,
Then you earn the stripes to stroke it.
viewtopic.php?t=115287

[Piledriver]

The forged pistons he found would be for a non stroker, would go together ~like stock, even clearances.
Should last about like stock too, as long as you can keep the heads sealed.
There should be a 96mm flavor of that piston... JE/Ross can do them too.
On a heavily boosted engine I'd take the thicker cylinders over the ~100ccs.

If you go through Wallys thread carefully, he laid down some pretty damned stout numbers with prepped stock 1.7/8L rods until the ~last configuration when he was pushing >450 HP and pulling 7500++ all the time.
Also note that motor was absolutely not Wallys first rodeo...
His new motor will probably be pushing the limits of a T4 crankcase... May need the steel side plates, and may need larger main bearings. (Pure conjecture)

The t1 rods are an advantage due to there being many choices, most cheap. Has downsides for latter reason.
I'd suggest the SCAT I beams if T1 journal and short strokes, come 22mm pin, have the meat for 24mm pins if you end up needing to go there using Porsche 100s or Volvo or Pinto 96s...

The 2" buick journal has an advantage because awesome rod bearings exist for that, and more cam clearance for longer strokes. The T4 2L is just a tiny bit smaller, and EMW has rods for that, and if the rods are set up for them, the great bearinsg (for a Dodge 2.2/2.4) are also a thing.
The latter small journal cranks will be more flexi than with either 2.165" vw journal.

For boost, I beam is stronger. The stock T4 rods are not weak by any stretch of the definition.
Far better than I have argued a properly designed I beam is always stronger than an H beam, all else being equal.
In the end, the H-beam vs. I beam thing is mostly a matter of taste.

The custom Crower rods I have for the 2.5L are I beams, and are certainly not lighter than stock, and they have 3/8" cap screws. (the 74mm Oettinger crank has 1.7 journals) Also a little longer than stock at ~5.3"... (stock 5" 1.7 rods will not even work with a 74 stroke, the pin will not clear the crank, at least with 1.7L journals)
That crank/rod/piston combo are probably fine past 9K, but will likely never see 7K unless the automatic misses a shift somehow...

I'd adore having coated trimetal rod bearings, but I'll have to suffer with the stiffer crank and huge bearing surface area.

[Clonebug]

Just a word about a turbo......Don't underestimate the Subaru turbos. If your displacement is going to be 2.0L and under then the WRX/Forester TD04L-13T would be an excellent choice in my opinion.
They are capable of 270 hp stock and there is a simple bolt on compressor wheel upgrade that will push them to almost 350 hp.

I use one on my 1679cc engine and have excellent boost characteristics with an ability to hit 23.2 lbs boost at right around 3700 rpm.

The good thing about them is they are available at swap meets for $20.00-$100.00 all day long.
I have bought three so far and $60.00 is the most I have paid. The other two were $30.00 and $40.00.

[Rickster]

Like Pile clarified above, I am pretty sure at this point that I will be building an 1800cc with stock dimensioned (or as close as I can get) parts.
I like the idea of the thicker cylinders for piece of mind. I'm thinking of just using the stock rods with Carrillo bolts and the forged Pinto pistons mentioned above.

Thanks you for the turbo advice as well! That was one of the candidates I was looking at, and it is nice to have some real world feed back on that.
As my first turbo build ever, I plan to keep the boost at 10-12 PSI. If I get bit by the turbo bug I may add a little more?

I do have a lathe and mill in my shop, so thanks again for the confirmation that the cylinders can be turned if needed.

Th information here is awesome, thanks again for all the helpful feed back

[Piledriver]

You are welcome, but---
Take pictures!
We all love pictures!

Search for RonWs build, he did a 2270 in a 912, awesome car, sadly later it got Subaru'd
The urge for mopowa is never ending......

[qaxa]

I've done quite a bit of searching here in the 4rum and I was just wondering has anyone ever used these pinto pistons or is it just a thing that they would work but no-one has used them?

[Piledriver]

You can buy the "right parts" off the shelf, so the advantages are minimal.
It only makes sense if you can score a set very cheap, or need one of the off the shelf several dish or pin height options.

[qaxa]

You can buy the "right parts" off the shelf, so the advantages are minimal.
It only makes sense if you can score a set very cheap, or need one of the off the shelf several dish or pin height options.

True. In some & many cases Volvo / Ford pistons are more expensive than JE's for example.

I was just curious as quite often there are deals over here (in Northern Europe) as there's lots of rally, rallycross and trashcan class builders here who use JE / Wössner pistons.

I have a 2nd core engine and if I will find a set cheap then I could buy those and bore jugs to fit them.