Performance wise what would be the difference between a 1970 442 W30 with auto trans VS a 70 442 auto with the W25 option?

 

Good question, since most of the difference is in the marketing brochure.

Both use the same P/N 406165 285/287 deg cam.
The W-30 has slightly looser piston-to-wall clearance
Both use the same size valves
The W-30 uses F head castings, the W25 uses E
Both have the same 10.50:1 CR
Initial timing is 10 deg at 850 RPM on the W-30 vs 12 deg at 1100 RPM for the W25 car
Both use exactly the same vacuum advance can
The W-30 distributor has a more aggressive mechanical advance curve
Intake manfolds are the same except for material (aluminum vs iron)
The W-30 uses a 7040258 carb. The W25 uses a 7040257.
Both carbs use the same 0.069 primary jets
Both carbs use the same 52C primary metering rods
Both carbs use the same AU secondary metering rods

It sounds like the only substantive difference is the ignition timing.

 

OW transmission and "performance rear end ratio" ?

 

I'd say virtually nothing. Some of us pure stock guys have talked about how the milder Olds combos are much better "bang for the buck," particularly in stock form. The '70 442 with OAI is a very solid combo and would give up negligible performance differences to an automatic W30. I guess you could take a look at torque converter differences too. Either way, the 442 with W25 is going to be more affordable than the W30.

And now I can **** everyone off and mention how the 4 speed W30 is overrated when you keep exhaust manifolds on it... way too much cam... they were designed to get headers swapped on them ASAP.

 

Good point on the trans, but we have to assume the rear axle ratios and tire diameters are the same, otherwise any comparison is meaningless. You could get 3.23 or 3.42 gears with either engine.

 

In Muscle Car Review, Diego said Fred Mandrick has a January 30, 1970, report from the Project Engineering Experimental Laboratories with some relevant data to this discussion...

As-installed (net) horsepower on the W30 auto versus 442 auto W25 is 306 vs 297. As Joe said, this must be due to ignition timing.

The W30 SMT had 322 as-installed. And touching on what 83hurstguy posted, headers on the W30 SMT added 46 hp.

 

https://www.hotrod.com/articles/hors...r-1960s-1970s/

 

Insurance rates did affect car sales. Beginning in the mid 60's the insurance companies started charging extra for performance cars. Stripes were just one of the criteria that triggered higher rates by the end of the 60's.
Roger Huntington wrote several in depth articles for Hot Rod Magazine. The one that pops into my mind at the moment is "Ram Tuning". It covered induction systems as well as exhaust systems and was loaded with formula's.
I really don't know if Huntington was overly optimistic, because we don't know what/who's car he used for his calculations.
....Just my two cents worth.

 

Insurance didn't really start pricing the cars out of reach for many till later.

 

There are too many variables in these comparisons to go by factory ratings. I'll bet you could take 2 identical brand new 442's back in 1970 and one would outrun the other. Test dyno engines were probably blueprinted. Production engines allowed tolerances (+ & -), coupled with assembly line tolerances. You can bat factory hp ratings around all day, but a good "SHOE" and tuner would leave you at starting line with your jaw hanging, checking to see if your car shut off.

 

I don't think anyone argues the unreliability of factory ratings from that period or the effects of production line variability. We have to assume that any accurate comparison assumes variables like driver skill, weather effects, rear end gears, tire type, etc are all equalized. My whole point is that from an assessment of the actual piece used parts in each, there is little difference.

 

There it is, the W25 option alone will not equalize performance.

Base version vs base version with only the W25 option on the regular 442 and the W30 will win every time. Weights about the same, HP is close, setup is not. 3.42 rear gear base standard on W30 vs 3.08 on regular 442, the transmission (M40), stall, and timing on W30 is more aggressive as well. Both of these cars up to their respective base factory specs + W25 and the only way the W30 loses is driver error or catastrophic failure.

As far as actual performance difference when new its a little tricky to verify. Most readily available 1970 442 road tests were for W30...

Automobile Catalog via simulation says the auto W30 is 4/10s quicker and 4 MPH faster in the 1/4 mile than the auto 442, again base to base. W25 on the base 442 will likely cut the difference in half...

 

Sorry, but I think you are really missing the point here. First, once you add RPO W25, the 442 is no longer "base". Second, comparing two cars with different rear end ratios is a waste of time. Same thing with including or not including items that change the weight of the vehicle. Obviously you can pick whatever ratio or options you want in either car and change the results. I ASSUME the intent of the original question was to ask about the effect of the O.A.I. hood on the 365 HP rating of the 442 motor vs. the 370 HP rating of the W-30 AT motor that already has O.A.I.. Again, if you actually compare the parts in the engines, the only differences are the head castings and the ignition timing. I stand by my original statement that the performance difference between two otherwise identically equipped cars driven by equally skilled drivers (and assuming manufacturing tolerances are equal between the two) would be negligible. And yes, the W-30 car will be about 25 lb lighter due to the aluminum intake. That's well under 1% difference.

 

A few years back I talked to an Olds engineer at Homecoming, he said he was the original designer of the W25 hood and they did plenty of testing and from what they found you would have to be going close to 100+ mph to get any advantages of "ram air." He also said it was one wide scoop that his team was designing and testing. After handing over the initial designs to the next department about time he saw it again it turned into the two scoop model we have all come to love. He said there was no research/testing done what so ever on the hood we have come to know. Now this guy was certainly old enough to be there, and sounded knowledgeable enough about the whole process but I never did do a background check on him . My point being is that the W25 hood does absolutely nothing for performance and if it does its because of the build/tune of one car's engine over another.

 

Your point is not correct. Go back and re-read your post. I agree that there is no "ram air" benefit. This is well known. The benefit is from the induction of colder outside air. Testing repeatedly shows about a one HP increase for every 7-10 degrees F that you drop the inlet temp. Going from 180 deg underhood air to 70 deg outside air can provide a 7-10 HP increase. There's a reason why Olds called it Outside Air Induction and not "ram air".

 

well, that's what he told me from all their testing, of course back then smoking and being pregnant was just dandy too.

 

Again, when he said there was no "ram air" benefit, he was correct. That does NOT mean that there is no benefit from the hood. The benefit comes from COLD air induction, not any "ram effect".

 

OK, to be clear he told me they found absolutely no performance benefit at all until after 100 mph+. I do remember him also saying no ram air effect but what I walked away from that conversation with was that its a cool looking hood that the engineering department found nothing statistically that added to performance. And I'm willing to back my point of view with the fact that 7-10 hp difference on two stock cars would not make enough difference to tell either by seat of pants or at the drag strip. The one with the hood could have come from the factory with 6-7 hp less than the 442 without the hood to begin with. Maybe with today's more sophisticated testing procedures we could find that there is a big difference but I'm just relaying what they found out back then.

 

Hmmm. Now you guys got me thinking. I am likely going to put a wideband data logger on the H/O this year to chase some fuel curve issues, logging air temps in the air cleaner and differential pressure relative to ambient with the OAI hooked up vs pulling underhood air would be kind of interesting. Granted, it's not a '70-style OAI... I did find my jetting changed dramatically if I raised the air cleaner lid to eliminate OAI... hotter air is less dense, car went way rich.