200 vs 250

[plastic-idol]

I'm looking for a new motor to start building. I've seen all the swap info in the tech section.

Overall, what are the pros and cons to swapping in a 250. Are the increases in performance enough to justify the hassle? I'm looking for some opinions and personal experiences.

 

[Anlushac11]

8)

IIRC you have to use Maverick motor mounts to drop the motor enough to clear the hoodline. The 250 makes much more torque than the 200 but it is limited by the same long stroke crank. It doesnt rev as well as the 200. But on the other hand how often do you rev your engine past 5500rpm?

I say go for the 250 because the low end torque will be even better than the 200 and you get the 50 extra cubes and as the saying goes

"No replacement for cubic displacement" I wish their was a drop in setup for a 250 in my Stang. I would welcome the 50 extra cubes.

 

[Anonymous]

I have been wondering about this myself...

Given 2 equally worked over engines, a 200 and 250. By worked over i mean all the reasonable performance mods (aussie heads and headers, ect.) you might do to a daily driver (not a drag car).

Given this situation, would you relly expect a real difference between the 2 motors.

You said much more torque.. are we talking 5, 10, 50 lbs? You also said nothing of HP... so i'm guessing that would be about the same?

I want a pepy motor that has good driving characteristcs (so my wife can drive it), but will also give me some good grunt when I stomp the accelerator... I'm not much of racers, but I do like to pull maxium Gs when accelerating to my legally assigned speed (or maybe just a little bit beyond ).

Also what kind of gas milage difference are we talking about?

 

[CoupeBoy]

I like to think of it not as a 50 cube upgrade, but a 25% upgrade. Go over and visit the Schjeldahl's Falcon Performance website http://falconperformance.sundog.net/facts.asp
And look at the rated outputs of the 200 and 250, for the same year, '69 is the first year both were available.
In '69 the 250 was rated at 40 more hp and 50 more ft/lbs torque
by '75 the 250 was only 8hp and 29ft/lb more then the 200 (ouch)
But it looks like with a health CR 9:1 - 9:2 there is a significant performance gain to be had with the 250 over the 200.

ron

 

[MustangSix]

The 250 is a torque monster. I'd consider it a better engine for a heavier car or for a cruiser that is pulling a big overdrive. But I think the 200 is a better HiPo candidate because of the shorter stroke and better Rod/stroke ratio.

 

[xctasy]

The rules are, any proportional increase in capacity in similar engine designs, doing nothing else, will give exact proportional increases in torque. Increase capacity 25%, increse torque 25%.

I do aggree with Jake on the even the US 200 being better dynamically than a 250. It has a better bore to stoke ratio, a slightly better rod to stroke ratio, and less friction due to smaller main bearings. Its nice low deck, a whooping 1.67 inches lower than a 250, also allows for much less weight and better fitting in early Falcons and 'Stangs.

A post 1971 Aussie long block 200 is superior to the US 200 in trems of smoothness and rod to stroke ratio only. They run a half bread 200 block with US 250 deck height and bigger main bearings. It is close to US 250 I6 weight.

We found some interesting things in Aussie sixes. When head, block depth, cam and carb are the same, a 200 six in an 84 Falcon kicks out 121 horsepower and 177 lb-ft of torque.(Net flywheel figures on an EGR equiped engine that was calibrated to pass the USA 1973 emmisions that Aussie had back then.) When you just change the rods and crank, nothing else, there is 131 hp and 224 lb-ft from a 250. Since the 250 is 25% bigger capacity wise than the 200, you'd always expect a 25% boost in torque. Which there is...its 27% in fact. But the power only goes up a piddly 9%. The peak maximum rpm in a 250 drops to 4800 from the 5500 rpm in the Aussie 200, and that's not because the engineers were worried about pistons exploding from any exra revs!. This is because if the same head, cam and carb is used, the engine fails to breath in proportion. But some of that extra 25% you'd expect in extra power is lost in the extra side thrust from having a lousy 1.51:1 rod to sroke ratio in the 250, verses an excellent 2.01:1 in an Aussie post '71 200.Even the slightly better than lousy 1.53:1 of the US 200 would help the small six have a better specific power per cube than a 250.

On sum up, though, I'd look at the US 250 because torque rules on the street. Spend any extra dollars on getting the carb, head and exhast equalling the extra capacity!

 

[Duane]

Looking at Clifford's site, it kind of looks like they recommend the 200. So I go buy a 200, and now I think I'll be lazy (and cheap) and just keep the 250 in the Mav, I've already changed it once...Besides, with a 460 in a 69 Mustang, I don't need to be hotrodding my work car too much! It just depends how fast (and expensive) you want to go, wild...200....cheap..250