I'll join in...how's this 2.4T rebuild/upgrade?

[724doorE]

Jay i'll pm you my work phone and if you want you can come by during the day and we'll check it out. I can show you my receipts for the work I had done (machining) and the parts I purchased.See Ya and Have a great holiday!!

[Bobboloo]

Jay I've got 12 of those cylinders. Chances are I have one you could use. No charge.

The machining cost can get pretty steep. Upwards to $1200. However since this is a T case motor your probably in pretty good shape. The T cases don't seem to get as warped as the 75' on 2.7S motors. i've got two 2.4T cases and both had line bores that checked out.

The work you should consider though...

1.verify the line bore
2.casesavers
3.deck the spigots
4.timesert the layshaft case studs

About $600 for the above work.

To go to 2.7 you'll need.

1.cut the spigots
2.oil bypass mod

About another $350

So your close to a grand for the case and you still need to address the heads.

[jim72911t]

I'll second what Bobboloo said: I've got a 3R/4R case on my '72T, and the line bore checked out ok. I'm was going to go with 85mm JE pistons in my stock cast iron cylinders (bored out, of course) but all this talk about using 86mm pistons has me thinking: I like the idea of 86mm pistons simply because I could then mount one of my 2.5 badges on the grille! 85mm pistons don't get me over 2.4L, so the 2.5 badge would be cheating. Are there head mods that need to be done? My heads were rebuilt a year ago so I don't want to disturb them if I don't have to. I'm going to use E cams and (hopefully) my T MFI, at least for a while.

BTW, small towns have their perks: My machine shop is only charging me $90 to do the case savers. I thought that was far too cheap, but after talking to my machinist (I'm a machinist as well, just not a Porsche machinist), I came away very confidant in his abilities, and he's done a ton of Porsches, especially small displacement engines.

Good Luck,
Jim
'72T

[Bobboloo]

Jim,

$90 for casesavers is a good deal. The cheapest I've had it done it for is $175. That's almost a 50% discount compared to what you would pay at Otto's or Ollies here in L.A.

So I guess Jay could figure the cost of doing the case for a 2.5 rebuild would be from $500 to $1000 depending on where he goes.

As far as the heads go, I guess it depends on the pistons. If you go for higher C/R with deep pockets and an 86mm bore you might have to fly cut the heads. I guess it comes down to how JE makes the crown of the piston. I would think if the piston crown is flat for the 1st mm going inward from the outer edge, before it starts to crown, then I guess you would be alright.

I've never done this conversion so I don't know. Maybe one of the knowledgeable people here can chime in.

[Tim Walsh]

Can you actually go as big as 86mm? I wouldn't think there would be enough meat in the cylinders for that and to still be reliable.

[Bobboloo]

86mm has been done. (see Tysons post) 86mm will leave you a 2.5mm wall between the piston and the CE ring gasket cutout.

86.7 might even be doable but you'd be covering new ground. You'd have a 2.15 mm wall and remember, the point where the cylinder meets the head is where the highest compression pressures occur . Obviously you'd have less room for error so your machining tolerances become more critical.

Too bad someone doesn't have a set of the factory 86.7 P+C's so we could see what they did.

One other consideration is the bottom of the T cylinder is only 89mm on it's outer dimension so if you bored out to 86.7 you'd be left with a skirt that is only 1.15mm thick. That's pretty thin.

[Tim Walsh]

So 86mm would be feasible and still be reliable? I'd love to have the extra little bit to make a 2.5 instead of a 2.4 but I'd be worried that the cylinders won't last for 70K-100K

[RichMason]

Tim,

You are going to be making so much money after you graduate - don't worry about longevity. You can buy another engine in a few years if this one doesn't last. Same applies to the case. My impression from my reading, which may not be as extensive as yours, is that the weaker case is an issue on engines that will be raced and abused. For the street car that you want to build, I'll bet that any case will do. Use your case and parts and do a budget rebuild the first time around. The next time you will be ready for more exotic work. In my view, you worked too hard to get your car to where it is to delay getting it back on the road for 6 months due to machining and budgetary delays. I also think really think you should consider using my engine. I imagine we can have it up and running for peanuts (one or two bent valves). You can use it while you build something else.