ea81's.. why'd they change em

[tailgatewagon]

guess what they still make the ea81

 

the legacys they make for the middle east are supose to have ea81s in them...... ill try and track down a source. for this.

[Snowman]

I kinda like the tendency for timing belts to break 'cause I got a perfectly good car for free because a timing belt went out on it.

[RedRX]

Europe and Japan did away with pushrods how long ago? Seems only the US/Australian V8s persist with pushrods. Some Aus cars only did away with cart springs (leaf) a few years ago too. An old design Aus car in both 6 and 4 cylinder formats had pushrods and fibre gears that chewed out. Old toyotas had 2 sets of chains for one OHC and they rattled like hell when stretched, with little or no power advantage. Even now Holden (GMH) are contemplating a 3 valve head using pushrods (using another horizontal pushrod!) to improve efficency and KEEP COSTS DOWN. Ferrari, Maserati, Fiat, Alfa Romeo, Lamboughini, even Jaguar used OHC for increased efficiency - even the old Bentleys and Stutz Bearcat used OHC for MORE POWER per cubic inch. Dont compare a 400ci with a 1.8 litre! Old tech EA82 may not be the ultimate in efficency but the flat 4 is inherently revable due to layout and oversquare design so OHC is natural progression.

ANY new OHC engine has cam belt durability issues - they are just NEWER - we are talking about engines that are HOW OLD here? All new Hondas, Toyotas, NIssans etc have change intervals of what.....? My old diesel toyota Hilux needs a new belt every 100, 000km and it revs to 4000rpm and makes a puppies fart of HP. As someone mentioned earlier - at least if the belt breaks at the worst u have to change it - i dont need to overhaul the damn engine!

[camosuba]

doesnt the new H6 have a timing chain?

[Stupidru]

I agree w/ gd, I've talked to Subaru mechanics about this & they all said the same thing...you don't need to split the case to get to valve train...although they also say the old engines (ea81) su*k. I like all 3 series...for me...ea81 is most finicki.

[archemitis]

yup big long timing chain.saved them an inch, or something like that.

[MilesFox]

Originally posted by dave valiant

I love my over head valve engines. I might have a dinosaur mentallity but I wont own OHC powered cars. I had one once a Nissan pickup had to change the chain gears tensioner and guides. Cost me over $200. and 10 hours of my life I'll never get back. As far as power the most powerful perfomance engine out there is an OHV. They dont have any longevity but what engine would making in the area of 7000 HP.

 

that was a nissan. s set of soob belts will be about 25 bucks and 4 hours time. dont refuse a soob t-belt motor over a nissan!!!

[gmcfan]

Don't knock the pushrod engines. Where would we be without them? still guiding horses around pulling carts, thats where!

 

I saw a chevy nova with a 989 HP PUSHROD engine once. Fast, awsome. Timing belts are a pain in the rump roast, and that is all there is to it. My uncle had to replace the timing belt on some car he had, and it took him 2 days. Had to pull half of the engine apart to get to it. I say on this point, we took a step back away from making cars anyone can work on.

[pm128]

So wait, timing belts suck because they have to be replaced every 60-100k miles.. and ohv engines rule, so nothing goes wrong with them , rods dont bend, etc.... fixing those is not that fun.

 

also with the ovc design you have so much more flexibility with the cams, you can change the phase of the cams on the fly, as bmw does, change the duration, change the overlap. You can have completely different cam profiles depending on engine rpm. Also developing a ohc engine is the first step into making a dohc engine.. which, im sure, according to some here sucks too.

 

p.s.

 

there is a reason why Fords 5.0 liter v8 make the same amount of hp as hondas 2l 4 cylinders.. and the v8 get worst gas milage, o and yea I knwo you can make the ford ohv engines have more power but look what it does to the gas milage, and notice how the car runs esp at idle.

[Guest taprackready]

4 cylinder, pushrod pontiac engines in pro stock and other forms of racing typically put out over 300 reliable, cheaper than import horspower. A plug for pushrod engines and a plug for american iron. Don't ever put it down. Check out the link below.

 

Bill

 

 

http://webpages.charter.net/imsa_gtu/docs/HRM-SD4article.htm

[Carter]

Someone mentioned a flat (or boxer) eight cylinder engine, but that's nothing: Ferrari once had a flat-12 as a Formula One engine, and BRM had a 3.0 liter F1 engine that was a flat 16 (albeit one flat eight on top of another flat eight). Here's a link to this engine that actually won one GP:

 

http://members.madasafish.com/~d_hodgkinson/brm-e-H16.htm

 

Also some of you seem not be keeping up on engine technology: there are many high displacement SOHC and DOHC V-8s available from American, European, and Japanese manufacturers.

 

Pushrod engines are still used in racing: NASCAR and NHRA Super Stock are two areas. But no one would seriously consider designing a pushrod engine for F1 or the IRL.

[bushbasher]

porsche once made a quad cam flat 8 in one of their race cars that made a 1000hp, and the car was also street legal and drivable if you put better ratios in the gearbox. I saw an article on it on the speed channel

 

oh and could somebody please show me a pushrod motor that can run 18 000 rpm and 800+ hp like a formula 1 car? And last lap after lap? I don't think so. A 7000-hp alcohol drag racing v8 means nothing about the advantage of pushrods, they do not go to outrageous rpms, nor do they last long at all.

 

GD you keep comparing modified ea81s to stock ea82s. If you worked over an ea82 or other ohc motor you can attain much higher rpms with more reliability than you could with a pushrod ea81 or other pushrod design.

 

There is nothing wrong with pushrods, they are fine for everything except high rpm. The amount of horsepower and torque you can make is not really related to where the cam is, but the rpm is affected, which in turn affects power, cause power is torque x rpm (with constants to account for the units)

 

The RS23… (4 valve/cyl dohc 3 litre v10 ferrari f1 motor)

Produces more than 250 bhp/litre;

Revs to over 18,000 rpm;

Sucks in over 600 litres of air per second at full speed;

Produces 160 decibels of noise at full speed, which is more than a Boeing 747 on takeoff;

Uses 75 litres of unleaded fuel per 100km;

Produces 150 sparks, and completes 300 piston cycles, in one second;

Accelerates the pistons at a force equivalent to 8,500G at maximum revs;

Operates at temperatures in excess of 110°C;

Generates surface temperatures close to 300°C;

Weighs just 90kg;

Includes 5,000 different components, of which 1,500 are moving parts

 

wait thats renault.. ferrari goes to 19 000 and produces 920hp

[Skip]

How quick we forget what board we are on

But alas maybe this is why we forget

"Coloni- Revised C3B chassis powered by a flat-12 Motori Moderni-designed Subaru engine, with transverse gearbox from the same company. An over weight and extremely ungainly makeshift machine."

pushrods, I don't see no stinkin' pushrods??

[bushbasher]

man that subaru 12 is a mess... thats when belts become scary. Im not sure whether f1 engines us belts or chains. They might even use overhead cams with gears... Mclaren is developing electromagnetic valves that can make their engine run over 20 000 rpm

[88rxsedan]

ohc is better than pushrod for mid range torque and high rpm power, and MORE POWER POTENTIAL because of flow rates, and the ability to run larger cam profiles because of less valvtrain drag.

pushrod is better for LOW rpm torque, mid range power..

you dont wanna go flinging your valvetrain around at 7k for long with your big tall cam and weak springs.. they both have their advantages, but for efficiancy, even with the belt.. ohc is the way to go

[calebz]

Originally posted by Skip

How quick we forget what board we are on

But alas maybe this is why we forget

"Coloni- Revised C3B chassis powered by a flat-12 Motori Moderni-designed Subaru engine, with transverse gearbox from the same company. An over weight and extremely ungainly makeshift machine."

pushrods, I don't see no stinkin' pushrods??

 

I was waiting for that one to come up.. that has just one timing belt.. Kind of a huge EJ motor..

[junkyardgabe]

all the bad head gasket i see are on ohc timing belt motor and subaru had to do something to get work back into their garages beside exhaust and cv joints

[88rxsedan]

Originally posted by junkyardgabe

all the bad head gasket i see are on ohc timing belt motor and subaru had to do something to get work back into their garages beside exhaust and cv joints

well.. there are PLENTY of high mileage stock head gasketed ea82's ive owned 2 with over 200k, and i had a freind with a TURBO at 250k.. he sold it, next owner popped the gasket with TOO MUCH BOOST..

[88rxsedan]

and every ea81 equipped car i see around here is either blocking traffic, or stuck behind a UPS truck because he dosent have the power to pass it.. thats another reason they changed.. the ea81 in stock and even bolt on modded form is fairly weak..

[pm128]

The ea81 should have a weaker head gasket, since in the ea82 you dont have the ohv craziness going through them..

 

however its probly offest since the ea82's make more power thus more stress on the head gasket..

[junkyardgabe]

i've owned both and i didn't see any power difference. plus with the slight increase in hp is compensate by the increase in weight.not to step on any toe but i'd take either ohc or not their both great cars

[Adam N.D.J.]

Actually as far as headgaskets go, OHC motors are more likely to blow one out cause of the force of the belt(s) pulling down on one side of the motor, there is a large amount of moving mass sitting on the head, plus most OHC motors use head bolts, which are suppose to be replaced everytime you do a hg. The OHV motors have less forces being exerted on the head, there is a very minimal amount of moving parts located on the head, and there are head studs. If you want to counter the head bolt/stud debate, go out, and remove your exhaust studs from one side and replace them with bolts, drive around for a week.

I am neither for nor against either OHV or OHC, each is a little better in some aspects than others. I have two of each, and have built many of both. As for the revving debate, I have an EA81 sitting in storage right now that revved out to 10K with no problem, thats as high as I knew it would go because thats all the higher my tach went up to. I never floated the valves in it. My old 427 would float the valves at 7.5 on the other hand. But thats another story. If I put the same amount of work into an EA82 that I put into that EA81, I'm pretty sure it could exceed speeds of 15K. The only problem with that is, if I did that to an EA82, the cruise rpm would prolly be about 6-10K, good stuff if your running Indy, but not the best thing for the freeway. Also you would prolly not be able to drop it under 3K without it stalling. Where as my EA81, I could drop it well below 1K and not have it die, I had it so low in rpms at one time that my tack sat on 0 and you could hear each cylinder fireing, with 4 other people witnessing it.

As for this overly huge OHV/C debate, it's rather worthless. Automakers go with engine designs that are currently common. I've built a 400 SBC that didn't have valves or a camshaft, rather it had special heads that contained a camshaft like device with round "lobes" in it with notches in it. As the engine turned, it turned this cam, and for the intake stroke the notches in the "lobes" lined up with either the intake port, and so on for the exhaust. If you've ever heard a SBC turn over 8K it's definatly a sound you will never forget. These are the way to go, rotary valves:

[Nomad]

Give me some of THAT!?

 

Are those commercially available?

[bushbasher]

i had almost the exact same idea for valves once and thought it was untried... oh well

[GeneralDisorder]

Basher - you can think whatever you like of EA81's - you haven't seen Qman's Brat in action...... now he's got two of em. Each running about 150 HP - these are not airplanes, and they are not highly modified. Slightly yes - but definately not "highly". Different cam, EA71 pistons (not stronger - just higher compression), and decked heads. With a Weber this combo really moves.

 

I will say again - the difference in HP of the NA EA81 and the NA EA82 is 15 HP, and this is due to the larger carb, and intake, and different exhaust. Also - this 15 HP is largely nullified by the higher weight of the vehicle. EA81's can pas UPS trucks easily. Power to weight ratio is basically the same. Come on over and I'll put the 175's back on my wagon. and we'll drag race..... I've had that car to 110 MPH. I've had it to 100 MPH with 28" mud terrains.

 

The reason most EA81's that are still around are slow is because they are old, and probably aren't running very well.

 

If I go with an engine with timing belts it WILL NOT be the EA82. Subaru didn't get it right - the belts suck - lasting only half as long as the EJ engines. The headgaskets are a weak link as well. The engine, while decent, does not hold up to the reliablilty of the EA81. My next plant will be an EJ - probably in my Brat.

 

And there is no reason that a pushrod engine could not be designed to go just as fast as any OHC - it's just a matter of buiding it. It would be more expensive, and have more moving parts - but anything is possible.

 

GD