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why bother with the 3.1?


Guest d3finitlymaybe

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Guest d3finitlymaybe

I have been doing some reading on it and it seems like you would spend near $5,000 to have it done right...balanced, machine work, parts etc...And from what I understand most people cant really feel a difference in power...The only thing it really seems to do is add more mid-range tq, around 30 or so? I guess my question is why would you dump 5,000 into an engine modification if it isnt going to produce much more power? I can see if you have a lot of money to do a stroker and turbo, because well...that would be tight. But i mean if your leaving it NA then i dont see the point...

 

If anyone has this, or has a dyno chart of a 3.1 then please post your feeligns on this...but so far i look at it as a waste of money.

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:cheers: For some of us, it has to do with what class you decide to race in. In my class in the SCCA Solo II events (BSP), you can only run with carbs. Every little thing you can do, helps it run better. We have to run against a lot of cars better (power and brakes) then ours. We get a good weight break and make some good power. But get hurt in the brake department (rear drums). So you have to have a well setup car to be a front runner in this class. Most of us use this info to help give us an edge. Would love to have disc's all around and a turbo to help. But it isn't allowed in the class. Hope this helps you understand why we do things like this. Rich. :2thumbs:
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I think there are several reasons for the desire to have a L6 stroker (3.0, 3.1, etc...) depending on who you are and what you are trying to achieve.

 

As RedNeckZ pointed out, some of it has to do with race rules. In this case, you have to try and maximize what you're allowed to do within the rules. Depending on how competitive you are, spending $5K for a engine buildup that nets you only 30hp may be well worth it if that means you get the necessary edge to win races.

 

Another reason for the stroker is nostalgia. Building a stroker allows you much more power potential than stock while maintaining a stock appearance and Datsun "feel" to the car. Also, keep in mind that these cars are insanely light, so a 30hp increase offers quite a bit more performance. Also, most of these $5K+ stroker buildups are netting anywhere from 250hp up to 300hp which is PLENTY of power for these cars and a considerable increase over stock, much more than just a 30hp.

 

A hybrid swap can certainly offer more bang for the buck, but that isn't necessarily the bottom line for every enthusiast. Make sense?

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And when you consider the increase over the STOCK motor, you are easily doubling a good stock L28, and almost tripling the HP of a decent L24 in stock trim.

Arguments could be made over "tuned" -vs- "tuned" but overall the increase is not just across the midrange for torque. If you are conparing and contrasting the differences between 3.0 and 3.1, than maybe it's valid, but it's STILL more where you can use it, so that alone is worth the effort for some people.

I mean, in Japan there was a custom crankshaft/rod/piston kit sold in the 80's that gave you a 3.5L L-Motor, and so far, I don't see anybody here with one of THOSE.

Would that only add to the confusion about which is best? For me, that would make it a REAL "350Z"! :lol:

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Guest d3finitlymaybe

thanks for al of the replies people. I had no idea that the stroker's can put out nearly 300hp, now it makes sence lol....I also hope this thread isnt going to get anyone (RedneckZ) into trouble ;) lol.

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I think some people think they are going to gain alot of power with an extra 300cc's over an L28. The difference between an L24 and an L28 is greater and that's not saying much. A 3.1 alone won't put out 300hp. You could send your head to Rebello or another reputable head guy and get more HP with a stock L24-28 than a 3.1 with a stock head. Adding displacement is an easy way of increasing torque but without headwork you're not going to get much more out of it. HP is about air flow.

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thanks for al of the replies people. I had no idea that the stroker's can put out nearly 300

 

As Clifton said above, simply increasing displacement does not increase horsepower from 150 to 300. SCCA GT2 Nissan's are limited to 2.4L, 2.6L, or 2.8L and they easily make over 325hp. The 3.1 and 3.2 stroker motors have gained an almost mythical status way out of porportion to the power gains the displacement increase enables.

 

Basically, any modified L engine (whether 2.4, 2.6, 2.8, 3.0, 3.1, or 3.2) will make most of its power through head modifications, cam selection, compression ratio increases, and/or turbo selection. Displacement is only part of the equation and, in the tenths of a liter increases we're talking about, its a small part.

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Guest d3finitlymaybe

but it is a good way to increase displacement, and then also increase torque, which is hard to make with bolt-ons and head modifications. But also like you said, for the small amount that we are stroking these engines..mainly .2 and .3 litres, and the power we get from it (Around 30+ Torque) I just dont see sence in it, mainly talking about street cars. Unless you just want the bragging rights or whatever. But thats just my two-cents.

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If you don't see any sense in 30 lb-ft of torque (realistically, more like 25 lb-ft over a similar 2.8 liter), then obviously you shouldn't go to the trouble!

 

Seriously, if you're doing a rebuild anyway, it's well worth the few hundred extra bucks to do the 3mm overbore/4mm stroker 3.1 build. IF a competent machine shop and engine builder are doing the work.

 

It's well worth it especially for a high-performance street car. Note that you can tune a higher-displacement motor more for high-end power while still maintaining decent low-end torque. i.e., for a given level of low-end torque, you could have a 2.8 liter built to peak at maybe 5500 rpm, or a 3.1 that peaks at more like 6200rpm and makes gobs more power.

 

To me, and most people who are of a mind to mod for more power, it makes PERFECT sense!

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