2.5 for whitey

[seanery]

So, I'm finally working, kind of, on Whitey's new engine. I've decided on a 2.5 six. I've got a 2.2T motor sitting on the floor of my garage in unknown condition and its missing the alternator, carbs, intakes, etc...I just bought a 2.7 7R case.

Here's my plan, I'm open to input and suggestions.

* 7R case, time serts and shuffle pinned as needed
* 66mm crankshaft, not sure if I'll use the T crankshaft I have or get a counterweighted crank
* 90mm Pistons and Cylinders, compression ratio? (9.5-10ish?)
* E or S cams, or some custom variant
* Richard Clewett's Electromotive kit for 911 (includes spark and all fuel rail, injectors, etc...)
* Single or Dual plug, not sure yet
* Heads cleaned up, machined to accept 90mm Ps

Whatdya think? Any thoughts? Different-but-in-the-same-ballpark ideas?

[tadd]

First question you need to ask yourself is how hard do you want to spin it. Under 7k or over 8? Money flows from there :-). Also depends on what you want 'feel' wise. Tractor or sports car? I'm a rev happy nut freak thanks to growing up on bikes so I spent (and spent, and spent).

Under 7k use stock parts and an S or mod S cam. Build a 2.7 or 2.8. Save money and enjoy. Nothing wrong with the T crank. They spin up quick :-).

If you want to spin it, youll need to do the oil mods, get a bigger pump and x-drill the crank. stay in the head flow sandbox which the factory provided you can get away with your clothes on otherwise that's another 1.5-2k in CNC time on top of rebuild costs. A 2.5 will be pushing stock 36 mm port heads at full chat on a heavy breathing cam like a DC 80 or RSR sprint. Heavy springs and Ti retainers of course. People poo poo the 906 grind as old and outdated, but it has really gentle ramps for high rpm operation on stock rate springs. Less wear, less friction. It has a lot going for it IMHO. It is also 'softer' in a 2.5/2.7. Titanium wrist pins are only $550 and that's 25g lost right where it does the most good. Worth looking into along with R&P rods.

Regardless of CR, twin plug it. It's $400 for the machine work. Put plugs in and bolt on the lower covers on (undrilled) and enjoy till you can afford to get the ignition pieces. It will future proof you for gasoline.

Best thing you can do is find someone that will let you drive or ride in their baby with the engine you think you want. See what they do. Make sure you hit traffic :-).

Good luck.

t

[burtm5]

I'd take the 2.7 apart to see what you've got. If the 70 crank is good, I would use the 2.7crank, case and heads (see that they are 35 mm btw) then get 9.5 pistons, e cam, SSI exhaust weber.(pricey) If the 2.7 heads are 32 mm and or the crank is bad. I'd do a 2.5 SS with a counterweight crank (E or S) webers, SSI 90 mm 9.5 cr pistons(36 mm heads) or 10.5 cr twin plug if money and RPM not a question. E or S cams or even better solex cams. (very pricey) either way you will likey. best Henry

[burtm5]

Tadd and I were posting at the same time. I like his response better than mine. oh well its all just a matter of money and rpm

[neilca]

Why 2.5? I get the impression this is a street car. If you don't have rules governing this, I would go big. Cubic Centimeters are better than cubic dollars. On the street I would bet you rarely see over 5000 rpm. Torque gives you that kick in the pants you want.

If this is a race car go with Tadds advice he knows his stuff.

[seanery]

its a dual sport car, sold the race car a few years back, i ilke the smaller displacement revy, snappy motors. I've wanted a 2.5 for a while and thought now was the time to build one. =)