Is it possible to have the same high end power that a sr has - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

fastpace · 07-26-2001, 04:04 PM

Hello to all, I was reading the post about the ka and the sr and I read about what cheater240 said about the bore/stroke and how it can affect the performance of the engine by either having a torquey engine like the ka or a high end power engine like the sr. I was wondering if it is possible to make the bore/stroke similiar to the sr bore/stroke even though there is a bigger displacement in the engine.
Thanks,

This is also cheater240 post from ka vs. sr topic.

I don't know what the bore/stroke is for the sr, but the ka is 89/96 mm. This motor is a stroker and that is the basis for its large torque numbers. The fact that my '91 redlines at 6900 rpm is amazing to me. I mean, with a 96 mm stroke, those pistons are really flying!

Generally, an engine with a larger bore to stroke ratio is preferred for high end power. This is because with a larger bore, bigger valves can be installed which promotes breathing. Now, a turbo changes all that. In fact, it almost negates it since you are artificially pushing the air in instead of relying on the atmosphere.
Anyway, I like to look at the total area under the torque curve. Huge numbers do no good if they do not last.

Boostaholic says his engine doesn't do much until ~3500. That leaves 3500-7000 rpm for driving use. That's not bad, but what about leaving the line? What I'm getting to is this, if you don't mind keeping the engine spinning really fast, then high end power is where its at for the race track. If your going to be running around town, then don't forget that low end.

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07-26-2001, 04:04 PM	#1
fastpace Zilvia Addict Join Date: Jul 2001 Location: Houston, TX Age: 39 Posts: 689 Trader Rating: (0) Rides Gallery: fastpace Feedback Score: 0 reviews	Hello to all, I was reading the post about the ka and the sr and I read about what cheater240 said about the bore/stroke and how it can affect the performance of the engine by either having a torquey engine like the ka or a high end power engine like the sr. I was wondering if it is possible to make the bore/stroke similiar to the sr bore/stroke even though there is a bigger displacement in the engine. Thanks, This is also cheater240 post from ka vs. sr topic. I don't know what the bore/stroke is for the sr, but the ka is 89/96 mm. This motor is a stroker and that is the basis for its large torque numbers. The fact that my '91 redlines at 6900 rpm is amazing to me. I mean, with a 96 mm stroke, those pistons are really flying! Generally, an engine with a larger bore to stroke ratio is preferred for high end power. This is because with a larger bore, bigger valves can be installed which promotes breathing. Now, a turbo changes all that. In fact, it almost negates it since you are artificially pushing the air in instead of relying on the atmosphere. Anyway, I like to look at the total area under the torque curve. Huge numbers do no good if they do not last. Boostaholic says his engine doesn't do much until ~3500. That leaves 3500-7000 rpm for driving use. That's not bad, but what about leaving the line? What I'm getting to is this, if you don't mind keeping the engine spinning really fast, then high end power is where its at for the race track. If your going to be running around town, then don't forget that low end.