Oh dear, this thread really is full of misinformation isn't it.
50 - 80kg comes from the fact that the late model cast chevs have a thin wall design to lower the weight of the engine, later model chevs also have some aluminium parts in place of earlier cast items.
I don't need to back it up as you just did, the ls1 weighs around 194kgs, add 50 - 80kgs and what do you get?
Yes, 260kg, what a surprise.
So you are saying that the SR20det + 5 speed is only 25 kgs lighter then the ls1 + T56, well that is even better.
I thought that the posted engine weight on here for a 4k + gearbox was 110 or 120kgs.
No, you have a chev for the fact that they are cheaper and easier to get power out of then building a 4 banger and the power delivery is a lot better.
The extra weight in Lloyd's car?
By your weights the 1uz is lighter then the SR and doesn't the SR handle pretty good in an E7 as a circuit racer?
Try driving a car in a straight line that makes a lot of power and see where you stand on that comment.
Ok so if you took the motor and box out and replaced it with a 13bt (plus box) making the same amount of power then you think it will handle better?
Look at the rear tyres, no matter what it weighs up front the car still isn't going to like to corner.
Just for something extra, these are some of my cousins projects that we have been working on:
LS1 into 300zx, we must have just thrown the engine in because it was an LS (all sold now).
350 chev into 300zx, all cast 4 bolt.
Maybe look into things a little bit better.