2.6L engine build

[Cornerlot]

Can a 70.4 mm stoke crank fit in 2.2L 2R engine case without major surgery? To get 'around' 2.6L displacement, it will need about 89 mm to 92 mm pistons. Does that require the spigots to always be bored, or were any 89 - 92 mm piston barrels sold for the smaller spigot sizes? What were the RS/RSR barrels?

I've heard of 89.9 mm bore sizes, what were they?

Trying to figure out what I already have in a vintage build from the 1970's ...

[Cornerlot]

Let me put this another way… Say its 1975 and you want to have a very light Pcar to street drive and look impressive at the autocross events. The engine you are working with is a 2R case 2.2L. Your 'Guru' says you need a 2.5L or 2.6L engine. The choices you see are:

A) stock 66 mm stroke and a large bore P&C set available back then. Do you bore spigots? 89.9, 90 or 92 mm?

B) longer 70.4 mm stroke crank and upping the piston bore, perhaps based on a off the shelf P&C set that will run good on pump gas. Is there a 88 mm or bigger bore without case mods? What are the choices?

Thanks.

[Richey]

You might have the Empi big bore kit .

[Trackrash]

A. Yes the spigots and heads will need to be bored for 90mm or larger cylinders. IIRC the 89.9 was a special to make a certain displacement for a certain race class. So forget about those. The 90s are easy as those are the same as the 2,7s.

B. Yes. I can't remember the largest bore without enlarging the spigots, 86mm? That is a bored out 2,2 or 2,4 cylinder. The 70mm crank AND rod set will drop right in.

These motors are like legos. Pull out one part and replace it with another newer, bigger, and more expensive piece.

My old motor was a 2,2 with 90mm cylinders, E cams, enlarged ports and webers. A SS2,5 and a sweet running motor.

Spend some time searching this forum, buy Waynes and Bruce Anderson's books and start hunting for parts.

[Cornerlot]

Originally Posted by Trackrash

A. Yes the spigots and heads will need to be bored for 90mm or larger cylinders. IIRC the 89.9 was a special to make a certain displacement for a certain race class. So forget about those. The 90s are easy as those are the same as the 2,7s.

B. Yes. I can't remember the largest bore without enlarging the spigots, 86mm? That is a bored out 2,2 or 2,4 cylinder. The 70mm crank AND rod set will drop right in.

These motors are like legos. Pull out one part and replace it with another newer, bigger, and more expensive piece.

My old motor was a 2,2 with 90mm cylinders, E cams, enlarged ports and webers. A SS2,5 and a sweet running motor.

Spend some time searching this forum, buy Waynes and Bruce Anderson's books and start hunting for parts.

Thanks for the info. I'm not searching for parts, then engine is together and running in the car now. I'm trying to understand what I have. Built in the mid-70's, it is 2.2L based and said to be 2.6L but without documentation as to how. One shop that had it out for a new clutch and timing chain 30 years ago noted on the receipt "engine has a long stroke crank", perhaps identifying a 70.4mm stroke crank by the single oil galley hole through the flywheel end flange. The current P&C combo is unknown.

A former employee of the shop that built it said they did build a couple of the 89.9mm x 70.4mm engines back in the day, so that's why I mentioned it.

Steve

[stownsen914]

You may be able to see some external markings on the cylinders looking from under the car if you haven't already checked that. Granted, it wouldn't tell you if they've been bored ...

[Trackrash]

Porsche did make an 89mm bore motor at one point. It had the 66 stroke and with 89mm bore and was just under 2,5L. Probably to meet some regulation at the time. I don't know how one would get 89mm cylinders, but who knows.

Another way to get 2,6 is with a 66 stroke and 92 mm cylinders. Back in the day those were racing cylinders with really high compression.

As mentioned, if you look carefully from the bottom, you may be able to see the casting numbers on the cylinders. Mahles would have something like 90ZN1W3 for a 90mm bore.

[targa72e]

from the description of crank single hole at flywheel flange that is a 70.4 crank. Based on the time 86MM cylinders (84 mm stock) bored out would be common. If you look at the cylinders from under the car you should be able to tell if they are Later aluminum or earlier cast iron or Biral which would help determine likely bore. displacement with 66 and 70.4 stroke with bore below.

86 43 2299.12056 2452.395264
87 43.5 2352.89934 2509.759296
88 44 2407.29984 2567.786496
89 44.5 2462.32206 2626.476864
90 45 2517.966 2685.8304

thanks,

john

[Cornerlot]

The heads are 2.2L parts with the PN 911.104.306.0R. The cylinders are aluminum, and the bottom is only marked with what I take as a inspection stamp "79E101" (the 'E' is sideways). No triangle, numbers, or names as far as I can see from the bottom.

Steve

[Geneulm]

Near ancient thread but using Mahle 89mm, meant to be used w a 66mm stroke, but used instead w a 70.4 = 2.62L.

Hope the thing is twin plugged!

[Cornerlot]

Originally Posted by Geneulm

Near ancient thread but using Mahle 89mm, meant to be used w a 66mm stroke, but used instead w a 70.4 = 2.62L.

Hope the thing is twin plugged!

No, only single plug. Its been running that way for 47 years.

[runner4fun]

So, I have a 2.2L engine and several parts left over from a prior 1983 SC project including Mahle Euro 90MM P&C set and a 70.4 crank and rod set. (I also have the heads, cams and cam towers to go with the 90MM P&C from the 1983 SC).

My question is whether the 90MM P&C and the 70.4 crank and rods will fit in the case, understanding that the spigots will have to be bored out to accept the 90MM P&C. If so, i presume I will have to use the SC heads, cams and cam towers.

If this works, it should be a 3L engine. What am I missing? Thanks

[SBell]

Originally Posted by runner4fun

So, I have a 2.2L engine and several parts left over from a prior 1983 SC project including Mahle Euro 90MM P&C set and a 70.4 crank and rod set. (I also have the heads, cams and cam towers to go with the 90MM P&C from the 1983 SC).

My question is whether the 90MM P&C and the 70.4 crank and rods will fit in the case, understanding that the spigots will have to be bored out to accept the 90MM P&C. If so, i presume I will have to use the SC heads, cams and cam towers.

If this works, it should be a 3L engine. What am I missing? Thanks

90mm pistons and a 70.4 crank would be a 2.7. The pistons from the 3.0 are 95mm and the 3.0 has different head stud spacing so I don't think the 3.0 cylinders/heads would go onto a 2.2 case. Also, an 83 would have a 9 bolt crank which would not fit into a magnesium case.

Sent from my SM-G991U using Tapatalk

[runner4fun]

Thanks Spencer!

[crater64]

Originally Posted by Trackrash

I can't remember the largest bore without enlarging the spigots, 86mm? That is a bored out 2,2 or 2,4 cylinder. The 70mm crank AND rod set will drop right in.

87.5mm Nickies should slip fit. 87.5 x 66 = 2381cc; 87.5 x 70.4 = 2540cc.