How Big a Bore Can You Be?

if you do some searching, both questions have been answered. OGTS can get you pistons, and the 265 chevy conversions to the 2.0 liter are bored .090 over, and from i remember reading previous posts, you can go to .120 over with the opel block, pretty stouty things in actuality. you can get anything from stock 7.6:1 comp ratio pistions in stock bore, stock bore for the flat tops that are 9:1, all the way up to venolia domed pistons with 11:1 and sometimes more.

Holy crap!!!! I didn tknow you could go so high. I had a friend back in the day with a 68 GTO he bored .70 over and I thought that was pretty thin on the walls.

What kind of HP do you think youd get out of a 1.9 bored 100 over with the 11:1 domed pistons, dual sidedrafts and a racing cam? Close to the 200 mark?

big bore

I've done almost the same as what your planning, but just a mild cam....depending on alot of factors, you could get anywhere from 130 - 170 I would think.
I've never dyno'd mine

steve

I've never heard of anybody breaking into the 200 horse range normally aspirated. Mine was guestimated around 170. It's not a mild cam, it's full tilt on a 2.0 11:1 base block. I'm pressing the limits on both tranny and rear diff at this level, even with the 5 speed. To go higher you need to look at tranny and rear diff changes. In a GT it can be done to higher horse but it can get too wild.

Engine block bore

I have an opel engine block that is suppose to be a 2060 This was done back when Martin Riemer and I wished our 1.9's were 2.0's (I was going to experiment) It was bored and steel sleeved. Its been so long ago I don't remember what the specs are. I believe the're chevy pistons were the same as a 56 or somthing like that All I know is it took 4 days to cut it out. (1 day a cylinder) The guy who cut it said it was the densest metal he ever worked with. I've still got it sitting in my garage waiting for me to get off my butt and find a head . I beleve the original plan was to use the 1.5 head. The compression was going to be 10:1 or 11:1 We were not sure what it would be.

Thom71GT said:

What kind of HP do you think youd get out of a 1.9 bored 100 over with the 11:1 domed pistons, dual sidedrafts and a racing cam? Close to the 200 mark?

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Without serious headwork you'd probably never break 160 hp. Most of the full tilt racing Opels out there (1.9 litre .040" over) are about 172-178 hp....there seems to be an imaginary 'wall' that makes breaking that number difficult.

I know of a couple of 1.9's flirting with 205 hp....a few 2.0's making 220+ hp (not for street use!), and a few streetable 2.2's making 215-225 hp. The head and camshaft are ultimately the limiting factors for hp production.

Bob

So how quick is everyones GT with these modified engines at around 160 - 170 hp?

0 - 60 times?

Thom71GT said:

So how quick is everyones GT with these modified engines at around 160 - 170 hp?

0 - 60 times?

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It depends on available traction, transmission gearing, and final drive ratio. I can attest that a proper close ratio tranny can be worth a bit here, and even more from 0-100. Anywhere from 5.5-7.5 seconds.

Boring

Thom71GT said:

Holy crap!!!! I didn tknow you could go so high. I had a friend back in the day with a 68 GTO he bored .70 over and I thought that was pretty thin on the walls.

What kind of HP do you think youd get out of a 1.9 bored 100 over with the 11:1 domed pistons, dual sidedrafts and a racing cam? Close to the 200 mark?

Click to expand...

Back in the day . . . late '50s, early '60s to the youngsters out there, it was very common to bore 283 SBs +0.125" to 4" for 302 displacement. Matter of fact, I have one in my garage that I built back in '69. That was in the days before "thin-wall casting" blocks though.

A 1.9 brought out to a 2.0 can do quite well. 0 to 60 and back around 12 isn't that hard to do.

http://opelgt.com/photos/showphoto.php/photo/4174/cat/500/page/1

If I had gotten on it the time would be lower.