Stroker vs re-gear

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wv_kid

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Saw a recent thread that S&J engines has a stroker for a little over 3k. Assuming a quality stroker can be built for that price, and regearing costs upwards of 2k, it sure seems like you might be just as well off stroking a tired 4.0 and keeping your factory ring and pinion. The extra low end of the stroker should handle bigger tires just as well as steeper gears, no?

Has anyone done this, run a stroker with a taller gear and bigger tires? My other car hobby is old Pontiacs and you see guys in the 11's with 3.08 gears using the 455 engines, whereas the shorter stroke engines need more gear to run that quick. Does the same principle apply here?

My first guess as to why this is not a more popular idea is that dana 35s and strokers may not play well together ...
 
Hmm. Take a TJ 4 cyl with 4.10's and a 4.0 with 3.07's. Doesn't the 4.0 outperform the 4 cyl in every conceivable way besides fuel economy?
 
SkylinesSuck said:
A stroker is not a substitute for proper gearing. It can help considerably for on road driving with shit gears and bigger tires, but it will still suck off road just as much. I have had a 4.0 with 3.07s, a stroker with 3.07s, and a stroker (two actually) with 4.10s.
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A stroker with 3.07 gears should put about as much torque to the tires as a 4.0 with a 3.55 gear.

What size tires were you running? I know a 3.55 gear isn't enough for huge tires anyway. But i tend to think a stroker with 3.07s and 32 or 31 inch tires would run pretty damned well under all conditions, and a hell of a lot better than a 4.0, no?
 
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Think of it this way:

When you install bigger tires with factory gears, you move the engine rpms out of the desired range for optimum performance.

Installing a stroker engine will indeed give you more power and torque, but it will still be turning at the exact same wrong rpm for best performance.

If you regeared first, your current 4.0 might not feel so tired anymore.

My Bronco has a STRONG 351W in it.

I had stock 3.55 gears with 35" tires.

Regearing it to 4.56 was a HUGE improvement in drivability, performance, and even MPG.

MPG came all the way up to just bad from formerly being jaw-droppingly bad.
 
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RangerTJ said:
Think of it this way:

When you install bigger tires with factory gears, you move the engine rpms out of the desired range for optimum performance.

Installing a stroker engine will indeed give you more power and torque, but it will still be turning at the exact same wrong rpm for best performance.

If you regeared first, your current 4.0 might not feel so tired anymore.

My Bronco has a STRONG 351W in it.

I had stock 3.55 gears with 35" tires.

Regearing it to 4.56 was a HUGE improvement in drivability, performance, and even MPG.

MPG came all the way up to just bad from formerly being jaw-droppingly bad.
Click to expand...

But my point is that the optimal RPM range for a stroker is lower than that of a 4.0, just as the optimal RPM range of a 4.0 is lower than that of a 4 cyl?

I think the answer that would make the most sense to me is probably something along the lines of "it helps, but not enough." You figure the stroker should have about 15-17% more off-idle torque, but going from 3.07 to 4.10 gets you more like 35% more torque at the wheels.

Also I guess it depends on whether you bump up the cam and move that power up in the RPM range.
 
The optimal RPM range stays the same.

If you look at a dyno chart of a stock 4.0 vs a stroker 4.0, the torque curves are close to the same, just at a higher level with the stroker.

Torque.jpg
 
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True, but the sweet spot is still the same.

If you're lugging the current 4.0, you'll be lugging the stroker as well, it just won't be as noticeable.

I'm not saying it won't run better with a stroker because it most certainly will.

I'm saying that you'll never get the full benefits until you regear.

When I regeared my Bronco it felt like it gained another 50HP.
 
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RangerTJ said:
True, but the sweet spot is still the same.

If you're lugging the current 4.0, you'll be lugging the stroker as well, it just won't be as noticeable.

I'm not saying it won't run better with a stroker because it most certainly will.

I'm saying that you'll never get the full benefits until you regear.

When I regeared my Bronco it felt like it gained another 50HP.
Click to expand...

That response makes perfect sense to me, both intuitively and mathematically.
 
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If you're talking about your 32rh,3.07's and 31s specifically then yes you'd be happy with a stroker. Its no v8,but it is what the 4.0l should have been. People use much higher gears with the 32rh than all other tj transmissions.

As to power band comparisons it would be rediculous to run a stroker at the same rpms as a 4.0l assuming you don't have a huge cam.

The jeep only needs so much power to go down the highway. I'm not lugging my stroker at 1800rpms and 1/8 throttle. All it does sitting at 2500 rpms is use more fuel
 
Here's something to consider in the gear vs stroker idea. Leaving the gears the same will keep the engine at the same RPM at a given speed. If your current 4.0 is lugging now at X speed/RPM, even with a slight bump in power the effects of side-loading will only be worse with a stroker, thus faster wear.
 
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