289 vs. 302
 

can someone tell me what the big difference between a 289 and a 302 is? It has to be more than just those 13 cubic inches, or the 302's wouldn't have been worth making. I always hear people scoffing at a 289, but then they mention the 302 and everyone changes their tone like its sucha better engine. what makes them so different?

unless i am mistaken, the 302 and 289 are the samew block, but the 289 is detroked, different heads. they all bolt together though. 289 heads on a 302 make good power.

well I don't know about all the tech stuff but I would much rather have A 289 then A 302. cause I think the 289 is A perfect engine you can have so many combinations and come out with so many diferent hp numbers from 200 to 400 hp. and still keep the light weight.

my bad if you can do the same with A 302 but I like the 289 better.

most of the people I know just go with the 302 so they can say they got A 5.0 engine.


again I am not puuting the 302 down but I would rather have A 289.


ford kid

im not sure but i think that a 289 is more for horepower and a 302 is more on the torq side. 302 are in trucks mostly that i have seen like a bronco. The parts combo is the same because all parts from a 302 and 289 are compatible. same block so everything lines up.

guys, it's the same motor. everything that applies to the 289 applies to the 302. it is just as easy to get HP out of the 302 as it is the 289. the 289 needs to rev more than the 302 to get hp, just as the 302 needs to rev more than the 351 to get hp. understand? we are, after all, only talking 13 cubes too.

De-stroked, so that means it can safely rev higher? Wahts the redlinie on a 289 VS a 302/351?

The 289 is much more than just 13 cubes smaller, IMHO. I would take a 289 for a 1/4 mile engine anyday over a 302. Stroke is where it's at, folks.I can't say that the 289 necessarily has a higher redline, but it reaches it quicker. The 289 heads had smaller combustion chambers, too.

Just my nickel

Take care,
-Chris

Rev quicker?!? Think about that, when the clutch is engaged, and teh engine is conected to the transmition, the only way for the engine to rev quicker (assuming no gearing changes) is to have more power. Period.

When they first started making aluminum flywheels for probes, there was a lot of debate about this on my probe board. But if you think about it, reving quicker would mean acelerating quicker, and the only way to acelerate quicker is to have more power.

The 289 is the fore runner to the 302. The 289 is a 4in bore by a 2.87 inch stroke. The 302 takes the same 4in bore and gives it a 3.0 inch stroke. You can make a 289 into a 302 and vice versa by swithching cranks and rods. Nothing more complicated than that. It is just a matter of 13 cubes, the 302 is a 289 stroker. Now heads, cam, carb, exhaust, and distributor changes abound in these cars. Generally, you will find higher HP versions of the 289 floating around but I think this is because when the 302 showed up in 68, the 351 was a year away, and the 390/428's were showing up in cars and so a really high proformance 302 wasn't necessary. Then came the 70's and the gas cruch, followed by the technology revolution of the late 80's-90's that brought the hp of the 302 way up. But lets not forget that butt-kicker 302 we all want, the boss 302. (used 289 rods, longer, and special pistons, strengthened block, but otherwise just like a 302 with radical head and cam treatment.)
Yes, the 289 will rev quicker because it has less internal mass than a 302 (if you have engines with the same power) but as for redline, most of the time engines are limited by the valve train not the bottom end assembly, expecially on short stroke engines. Extra strengh will help keep it together though. The 289 does have a slight advantage in rod to stroke length over the 302, but it is pretty small.
If it were me, I would build a 302 because the parts are already there and the valve train can be built to get to 6500 pretty easy so why not just go with the stroker and get the extra cubes. And a 302 (347 for that matter) can look exactly like an old 289 from the outside.

Wrong, but nice try. With that logic, bigger engines would always be faster, and they're not. probably the single biggest factor in how fast an engine revs is it's stroke. The shorter the stroke, the faster it revs. Let's say you have two identical engines, except for the stroke (ie: 289 & 302). To make this simpler, let's say engine one has a stroke of 4 inches, and engine two has a stroke of 3 inches. The energy required to rotate engine one 4 times will rotate engine two 5 times. That means that engine two will reach 5000 rpms in the exact same amount of time as it takes for engine one to reach 4000 rpms. The same energy expelled will yield quicker results with the shorter stroke. This is why "de-stroking" engines was the hot trick in the "good old days". There are dozens of books on this at bookstores everywhere. if you are still in doubt, check out your local Barnes and Noble.

Take care,
-Chris

No, by my logic the more powerfull engine revs quicker, becasue its acelerating quicker. Think about it this way, in my probe, 6700 RPM's in second gear is 60 MPH. If my engine revs to 6700 RPM's, and I'm in second gear, I am going 60. These are facts. The only way to make my engine rev to 6700 RPM's faster, is to acelerate faster. Acelerating faster means more power. I can make my stroke wahtever I want it to be in my probe, but if I dont have more power, I wont get to 60 faster.

a 289 with 300 HP in a 3000lbs car is 10lbs per HP
a 302 with 300 HP in a 3000lbs car is 10lbs per HP
a 429 with 300 HP in a 3000lbs car is 10lbs per HP

a 2.0L probe with 150 HP that wieghs 1500lbs car is 10 lbs per hp.
a motorcyle with 50 HP that wieghs 500lbs is 10 lbs per hp.
a diesel truck with 850 HP that wieghs 8500lbs is 10 lbs per HP.

Get my drift?

pkrwud's point is this. While your analogy is very nice, it isn't exactly true. yes, cars that make 10HP per lbs will accelerate the same, all else being equal. but, one motor, let's give it the fictitious name "289", will have a different powerband than another motor, let's call him "302". With the shorter stroke, it takes "289" less time to make it's 4 cycles. "302" takes a little bit more time to make his 4 cycles. it takes a longer time for the piston to travel from TDC to BDC and back in "Mr 302" than it does for "289". Therefore, "289", using different wording, rev's quicker. Even if "302" is making more total hp, it takes him longer to make the cycle (rev) to eventually make that HP. Understand 72 Grande?

If you want to start talking about power bands, then peak power mean's ****. What then matters is average power over the RPM's that you have to drive in, the RPM's that you have to drive in is determinded by gearing. But were gettin off topic.

Its just phisics, F=MA. If M stays the same, and A increase's, F has to increase. More F, same M, there has to be more A. More A, same M, there has to be more F. No fighting it.
A can be measured by either the speedo or the tach. It can be measured by the tach because the ratio's dont change. So if the tach climes faster, the speedo climes faster. If the spedo is climing faster, the car is acelerating faster. More A, same M, more F. The only way to make the tach clime faster without changing the wieght, is to have more F.

In as few words as possible -

"Reving faster means acelerating faster. It takes more power to acelerate faster."

I think almost everyone has missed the point here! The 289 should be stroked to 302, 331, or 351, whatever you're comfortable with, for the power you want. The bottom end must be made compatible with the RPM where you intend to make peak HP. That might require high end (read expensive parts).

The heads, intake, cam, and exhaust will have to be right for that power range. At the same RPM, you won't match the power with less displacement. That's an old hotrodders adage "there's no replacement for displacement". Actually that's only true for "normally aspirated engines", no power adders..

When the engine's torque curve is determined, then the rest of the car must be set up to optimize that engine's character, or else all bets are off. With everything else optimized, the higher displacemrent engine will always win.

That's why most racing classes specify displacement. Destroked engines were only produced to fit into a lower displacement racing class, not because they produced more power.

Rev

Physics, did someone mention physics..Thats my area of intrest.

You cant use F=MA (Force = Mass X acceleration) in this case. Thats like applying Newtons law to Singulars and Horizons of Black Holes.

Think of it this way. YOu have a large tire, and a small tire. I will exagerate to make a point. Say you have a 33 inch tire, and one that is 17 inch. Put a white mark on each of them. Put them next to each other, and roll them down your driveway. See how many times the smaller tire rotates when the big tire turns one revolution. You'll then see what were talking about.

thats a good explination of a gear ratio, but what does that have to do with any thing?

Thats simply not true. How about a s2000 vs SVT contour? or an NSX vs a Mustang GT? Even amongst cars witht eh same displacment, set up for the same type of drive, engoen aretchure makes a huge differnce. A 2.5L ford duratech couger will be trounced by a 2.5L mazda kl-03 mx-6.

It has alot to do with it. Look at the larger tire being the larger stroke engine. That would make the smaller tire, representitive of the smaller stroke engine.

Lets see, I'll try to make this easy.The crank rotates 360 Degrees, a tire is 360 degrees, a larger stroke has a larger "Cirlcle" than the smaller crank.

Just think of the white mark I said in my first example as one of the throws on the crank.

Does that clear things up man? Not raggin on ya, we all start off fresh at sometime. But man you have several experienced engine builders here all telling you the same thing, its time to start reconsidering who's right. Just gotta know when to fold in.

Merc-

The tire analogy was excellent. I'm usually decent at analogies, but that one was short and simple. very good.

72-
I'm not talking power, I'm talking speed. They are not the same. A shorter stroke engine will reach any rpm faster than an engine with a longer stroke, all other things being equal. Period.

You want to start talking physics? Look into piston speed. That's what regulates an engines' attainable rpm. Again, the shorter stroke wins. There's a book out there called Auto Math that explains it really well. Buy it.

Take care,
-Chris

Were talking about the same things, juist drawing difernt conculsions from it. I made an animation.
http://student.csumb.edu/ac/barnettp...rld/stroke.mov

Yes the piston is moving faster in the 302 than the 289. BUT! the crank is still spinning at the same rpm!

And you cant increase the speed of the crank without increasing the speed of teh shole car.

Increaseing the speed of the whole car is determined by f=ma.

That quote should have included the first part.

"With everything else optimizd, the higher displacement will always win".

Rev

To make any motor RPM quicker, the key is in the weight of the rotating assembly. That's why people knife edge cranks, use crank scrapers or windage trays, titanium valves, titanium retainers and keepers..its all in the rotating mass. Regardless wether is a short stroke or long stroke, the same rule applies, get the weight out and get into your powerband quicker. Launch as close to peak torque as possible, and shift within 200 RPM of peak HP. Seems to work.

Ron

There are so many things wrong in this post I'm just going to pretend i didn't see it.

Why is it that every single professional drag racer use titanium valves, and alum. rods? Why do they use alum driveshafts..or in prostock do they use carbon fiber drive shafts? Why do they use hollow axles...get the weight out. It takes HP to spin a rotating assembly. The less HP required to spin the lighter assembly, the more hp goes to the rear wheels.
Why do big block engines not RPM quickly and small blocks do? It takes more power to move that massive rotating assembly...and it's wasted, not going to the rear wheels.
The theory of a 300 HP 289 at 3000 lbs= 10 lbs per hp, and the 300 HP 460 in a 3000 pound car is still 10 pounds per HP, but boys and girl, measure how fast the engine accelerates to peak HP on the big block vs the small. The small block will kick butt every time on the big block, because it has less rotating mass to accelerate, even though the HP is the same.

Ron

Or to simplify even more...I have 2 cars in my driveway...one is 2000 pounds and one is 3000 pounds...using 72grande as our power source to push both cars, which one to you think he will move first?

A few more questions 72grande...here is a location for the Dyno results of my last (naturally aspirated) 347 that I completed last October..
http://media.bigstep.com/shop/2/29/3...3350753206.JPGYou will notice it made 486.7 ft/lbs of torque at 5600 RPM and 604.6 HP at 7200 RPM. Where do you think you would set your launch RPM and your shift point?

Ron

As I said previously, higher displacement will always win "IF" the power peak is at the same RPM (and assuming normal aspiration). This is not just supposition, it's a known fact.

Rev

This thread has gone in so many different directions, it's starting to resemble an octopus.

72-
...until the parts reach their maximum speed. Then the 289 will have a higher rpm. Look, I'm getting tired of arguing this with you. You are very creative, but wrong. Facts are facts, and theories are theories. What I'm telling you is scientific fact, and I've already given you the name of one book that verifies this. I enjoy helping people here, but my time is worth more to me than to debate something with someone who won't accept the facts.

Good luck.

Take care,
-Chris

Does anyone in ANY racing class destroke his engine to less than the rules allow?

Rev

I started this whole long thread with just a simple question, what is the difference between a 289 and a 302? And for all the resplies that have been added to this thread, i've gotten very little feedback for my question. so far all i've been told is that the difference is 13 cubes and the stroke length of 2.87'' and 3.00''. Is that the only difference? What are the benefits of stroking an engine? Please try to stick to the point when answering. thank you all, i've had fun reading your responses.

Jason

The benefit of stroking an engine lies in the amount of torque the motor will produce. Torque being that ,which gets then car moving down track. The point in the RPM range where peak torque is developed and the point where maximum HP is developed, are dictated by how the displacement is built. As the stroke increases the lower in the RPM range the peak HP and torque will occur. However, a longer stroke motor will produce less peak HP but more peak torque. Short stroke engines produce peak power levels at a higher RPM and can produce a higher peak power, but less torque. You have to make a decision on how your motor will be built based on your vehicle weight, a standard or auto trans, gear ratio's and the rest.
As an example, I race a fairly light car, and leave at a fairly high RPM (5400) , so I do not need a whole bunch of bottom end torque to move down track. (BTW, I can compensate for less bottom end torque by adding something like N2O).
A heavy car, with an automatic for example, needs a lot of bottom end torque to get rolling, if it doesn't have it, it will not perform well.
David Vizard has an excellent book available..."How to build HP" volume 1&2, worth while reading.

Ron

On a street car, try to make as much lowend torque as you can hook. In the real world, all other things equal, a 300hp 460 will smoke a 300hp 289 because of the huge torque difference. There's an old saying - "Horsepower sells cars, but torque wins races". Destroke an engine to rev to the moon, and you've effectively made a larger, old tech, honda V8. Stroke it, and you've made your smallblock much more like an old school big block (ie 427cid windsor vs 427 side oiler). In a street driven 289 vs 302, it's not going to matter. There really isn't going to be enough difference to really feel. If you want to go stroker, it's better to get a 302 block because of the longer sleeves. The only differences between a 289 and a 302 are the length of the stroke, as discussed before, and the actual length of the cylinders. There's no problem putting a 302 reciprocating assembly in a 289 block, or even something like a 331, but I wouldn't personally put a 347 or 355cid stroker kit in a 289 block when 302 blocks are so cheap and easy to come by.

If you can get the 302 to make peak power at the same RPM as the 289, the 302 will make more torque and more HP. I'll second Ron's recommendation for David Vizard's book. Another good book is DESKTOP DYNOS by Larry Atherton.

Rev

What happened to 72grande? I have been waiting for his recommendation on my launch RPM and shift point RPM....

Ron

Maybe he reconsidered?

Rev