what displacement engine

[weldvair]

To begin, this is a hard to answer question...I have been restoring my 1971 Ghia vert full
time for 4 months & it's time to address the engine.

The engine is a stock 1971 1600 dp that was locked up. A friend
got it to turn over after using a gal of bp plaster. When I drained out the oil there
were small pieces of metal & about a pint of water.

I have a guy that will overhaul the engine but. I do not know what I want & need advice. I
want to increasing the hp for a street only driven car. I want torque at low rpm.

I would like a explanation of different displacement engines, the approximate cost of each & which you would be your choice.

I'd like to start by increasing the bore


Thanks Don

[Marc]

The cost is going to vary depending on how much of the work you can do yourself and the quality of the parts & workmanship you're paying for - a "stone-stock" engine can run anywhere from <$1000 to ~$3500, so it'll be easiest to speak in general terms about the difference in price compared to a stocker of commensurate quality. What good parts you have to start with can make a big difference in both the final cost and what options are open to you if you use them, too. The case is a major expense to replace, hopefully it's in good enough condition that it'd make a sound foundation with not too much machine work. Carburetion cost can escalate quickly; other ancillary items like heat exchangers and clutch components need upgrading by the time you get to around 1½ times stock output.
And let's be clear at the outset, unless you're also going to budget for a "built" transaxle you probably shouldn't be thinking about anything too radical. At double the stock horsepower a stock trans should still survive (barring any serious abuse) but by the time you get to tripling it all bets are off. I built a nice street 1775 a few years back using all new parts (other than sheetmetal) and it would easily have cost $4500 retail.

One could write a book or two about the many engine combinations possible (and there are a few out there already) so in the interest of brevity could you narrow the field down to what your expectations are (budget, mileage/fuel requirement, what type of driving you'll be doing, etc.)...if you have aspirations of drag-racing it now and then, how quick would it need to be to make you grin?

[weldvair]

I will be doing street driving only...just want a little more reliable power.

I used to drive a 356 so that is about what I am looking for....75 to 90 hp.

I am thinking of increasing the bore & adding more carburation. however
I have available to me a 1600 w/a street cam(10).

Don

[Marc]

Maximum bang per buck, still using stock heater boxes and a street exhaust system, in that HP ballpark would be a 1775 or 1835 (using "thickwall" cylinders for the latter if you want any longevity) with a mild cam and dual 1-bbls (Solex H40/44EIS "Kadrons", Weber 34ICTs/EMPI clones, Solex 35PDSIs). If you stay conservative on the cam (as in, one represented to peak by ~5000 RPM), a stock valvetrain and non-counterweighted crank will suffice but you'd be well-advised to have the crank/flywheel 8-dowelled and use a HD glandnut to keep them together. There's ~75HP without much cost or drama.
For ~90HP, you'd up the ante to include a counterweighted crank/lightened flywheel, "solid" rocker shafts, HD springs & pushrods, intake port work, larger heat exchangers and merged-collector exhaust, and dual 2-bbls (40 or 44IDF Webers/clones). With the head work and less-restrictive exhaust, it's justifiable to go even larger on the bore to 94mm (1915cc) ...the cylinderwalls, while a bit on the thin side for a heavy car, have proven to be adequate - just don't expect quite the longevity of the 90.5s or thickwall 92s.

Back in the day folks would frequently build an anotherwise stock engine using 87mm cylinders instead of the stock 85.5s - that would up the displacement from 1585 to 1641 with absolutely no expense beyond the difference in the price of the pistons/cylinders, and raise the C.R. slightly in the bargain. Problem was that the cylinders are just a little thin and don't tolerate any overheating excursions, making it a questionable choice for the small gain; these are still around, but see less and less use. There were/are also available "slip-in" 88s which get you 1679cc, but they're like tin cans with fins and IMO have no place in a full-bodied car. "Machine-in" 88s existed too, but since the price of the machinework to the case & heads was identical it was much more popular to step up to 90.5s (1775cc) even if they weren't really well-suited for a stock carburetor. Nowadays there's an 88mm set that requires no case machining yet maintains nice thick cylinderwalls where it counts by virtue of opening up only the heads - if I was to build a "stock" motor and willing to sacrifice a little mileage for better torque, I'd use those...the stock carb will still work fine, and you could forego the 8-dowelling unless you intend to drive like a jackass. Far off from your 75-90HP ideal, but still noticeably peppier than a 1585.

It's not mandatory to incorporate a full-flow oil filtration system, but generally considered to be wise to protect your investment. Avoid the setups which plumb a remote filter and cooler in series in place of the stock cooler - determined to be a bad idea 40 years ago, but that word still hasn't spread well.
However, even at the 75HP level it becomes possible to accelerate quickly enough in 1st and 2nd to starve the oil pickup - so some kind of sump extension, if not a full-on "deep-sump" should be in the plan too.

[weldvair]

Thank you...that's the kind of info I need. Any other ideas.