Overhead cam VS pushrod design? Which is better?

[e_racer1999]

What engine are you talking about Jason? The L series, or an S2000? Because an L28 series put out something like 135 hp out of 2.8 liters in the last version. That's 48 hp/liter. Let's check my truck again as a comparison. 285 hp / 5.3 liters = 53.77 hp/liter. There are many more V8s out there with more power per liter than my truck, so please don't get hung up on new V8 vs old L6.

Jason you could be talking about the theoretical pushrod L6 vs the real OHC L6 like Dave was earlier, but I really don't see why this efficiency argument stands up any better than the reality argument comparing the OHC to OHV liter per liter.

As far as weight are you talking weight per liter or weight per hp or weight per cylinder or what? I'm much more interested in weight per hp, and the V8 whips on the L6 in that regard. The old iron block 350 with aluminum heads and water pump weighs 40 lbs more than an L28. Just 40 lbs, and the weight will be set back further in the chassis if you use the JTR mounting position. The new all aluminum V8 is supposed to be lighter than the L28. I guess the rotary really wins this weight battle though. Point is, L28 is a HEAVY engine. V is the way to go for weight because the block is half as long, and that's why you see most car manufacturers going to the V setup.

again, what i'm saying gets twisted. i'm not comparing the L-series to a V8, i'm comparing a like for like on a pushrod motor for a OHC motor. comparing an SBC to a stock L-series is kinda nuts; what i'm referring to would be an OHC (or DOHC) V8 to a pushrod V8 (as per one of my earlier posts) the reason that i am making these comments is in reference to the efficient was the heads can be set-up, i.e. multiple valves per cylindr, i.e. better breathing. if i was going to compare the l-series to an sbc i would definitely go a different way in taking that argument, and it would more than likely have nothing to do with power.

[jmortensen]

Once again, I'm not twisting your words, or Dave's, I'm trying to compare REAL WORLD situations. If you guys insist on comparing a mythical pushrod V8 to a mythical OHC V8 or a theoretical OHC 6 to a theoretical OHV 6 fine. The benefit of that discussion will be just as theoretical.

As I have said multiple times now, I voted for the OHC in the poll because I believe it to be a superior design. I haven't seen anyone who disagrees with you or Dave or anyone else about that. Maybe whoever voted for the OHV engine will speak up. Until then you guys are preaching to the choir, but in the most useless way (comparing theoretical engines to one another).

I'm just trying to dispell the myths about the OHV engines in Z's. The easiest way to do that is to compare real evidence. As Lance said "This debate will go on forever unless you define the question to a specific point...." It really seems like nobody on the OHC side of the argument is willing to do that. I'll bow out again until somebody wants to talk in terms of reality. Right now you might as well be arguing whether chocolate or vanilla ice cream is better.

[=Resurected280=]

This subject was brought up under another thread. This is a debate wether the z v8 transplant is worth the trouble? With engine style is better? Which engine revs higher? Which one is older? BAsically which do u prefer and why do u prefer it?

This is the original post that started this thread, which seems to be asking which engine is better to put in a Z, not which one is better theoretically.

[auxilary]

That's because Honda designs their motors for low rpm effciency and high rpm output- ala VTEC. That way, you get fuel milage and horsepower.

BTW: No stock Honda Civic motor (B-series, D-Series, K-series, anything) ever reved to a factory-set 9 grand.

And I vote for OHC. Why? Ever head of a little thing called valve float? Plus, I like having my multi-valve cylinder heads.

B16A2 99-00 SI motor has a redline between 8-9k rpm. revlimiter at 8200rpm

B18C5 in the integra Type R has 8400rpm redline to 9k

F20C in the S2000 has a 9-10k rpm redline. They upped it to 2.2 liter and dropped the redline by 1k for last 2 model years

My L24 had some massive valve float at 6000rpm

[jmortensen]

My L24 had some massive valve float at 6000rpm

Something was wrong with your L24. Stock L24 should do 7000 rpm no problem at all IME.

[CoastGuardZ]

So I've done a little thinking (because that's all the thinking I'm allowed to do )

Comparing a 6 to an 8 is ludacris. Except for the fact that the original question asks - ... is the Z v8 transplant worth it? But keep in mind it is asking for opinions, not fact. Although it does NOT state for what reason. Power, Emmisions, Gas Mileage, Availability or even Aftermarket support. We can only assume that power is the goal. So if you were looking for the most bang for the buck, I believe a SB v8 is the answer. I think I would personally go with a built Ford 302 because "Hey, they sound so damn good". Although puting a 5.0L in a Z would be like wrapping a turd in gold, IMHO.

Now lets say it was for the most technology... How about Ferraris variable valve timing system thingy? The lobes are cut 3-D like and The damn cam actual moves laterally in the head. That's some neat crap... yet way off topic.

It may be easier and cheaper to get more power out of a american v8 but you could better gas mileage with the 1.6 that was in my 86 Sentra, I used to get 45mpg on the Interstate at 65mph with the factory optional 5spd. :surprised

Originally posted by jmortensen

V is the way to go for weight because the block is half as long, and that's why you see most car manufacturers going to the V setup.

"Most" was a good word to use...

Chevrolet, the main v8 manufacturer in debate here, recently ditched their very popular 4.3L v6 for their small pickups for the new Inline 5 cylinder. Overhead cam, less cylinders, less displacement, more HP and an inline engine to boot ... hmmm However, it does generate 25 ft/lbs less torque. And yes I am aware that the old style (S-10) Blazer is still in production and comes with a 4.3, and also that the 4.3 is the non-v8 in the Silverado, but I do have a feeling those will both change in the next few years.

Anyway - I'm sticking to L motors because I'm too emotionally involved with Nissan. In fact, on my drive home from work today I was even giving thought to... GASP... fuel injection :eek: . Or even... Double GASP!... Turbo "Someone get a Medic, this guys out of his mind :stupid: "

Also, if I was looking for power to weight ratio I would build a turbo charged 300hp VW Beetle... you know with driver you could come in at less than 1500 lbs! Or maybe even a SBC powered rail style dune buggy.

Oh and for the record... we all know that MINT CHOCOLATE CHIP is the best Ice Cream :lick:

Nate

[auxilary]

I have an answer to that 4.3L v6 analogy...

Those motors come from an era when manufacturers did not care about a motor lasting longer than 100k miles, and certainly wanted to do their best to turn as much profit as possible.

That era was the 80s, when the big 3 produced some of hte biggest turds ever. Fire catching Fieros, 3.8L v6 ford blocks notorious for blowing headgaskets, I4 in oldsmobiles that died pre-100k miles were all too common. That's why Japanese compact cars started shining through... All of the sudden you had little cars that offerred excellent fuel economy (honda civic CRX HF was rated at 48 city/56 highway mpg!), reliability and comfort for a low price. This is how honda, toyota, and nissan established themselves in the average commutter market. Sure they didn't make a big profit and spent more time and research on refining motors...

Something that GM is now starting to do with their cars and trucks.

[CoastGuardZ]

I have an answer to that 4.3L v6 analogy...

Those motors come from an era when manufacturers did not care about a motor lasting longer than 100k miles, and certainly wanted to do their best to turn as much profit as possible.

Hate to burst your bubble on the 4.3 man, but your statement has no factual basis.

My mothers 89 S10 blazer with 4.3L Z code engine was sold back in 2000 with 210,000 miles. other than gas, oil, and regular tune-ups the only things done to that engine were 2 starters, 2 alternators and 1 water pump. And this is not an isolated incident, I'm in the vicinity of two other 4.3's daily that both have over 150,000 miles with minimal maintenance. The 4.3L has a great track record, keep in mind... it's essentially a 350 with 2 cylinders cut off. It also got the same or better mpg's that my 3.3L Frontier gets.

Not to confuse you, I'm completely PRO Jap car, I just know that the 4.3 was/is a great engine.

Side note: My friend back in high school had an HF CRX. Couldn't get out of it's own way, but damn $5 in the tank and he was good for a month! I was lucky if $20 would last me a week in my '88 C1500! And that's when gas was $0.89 cents a gallon... ahh the good old days...

[jmortensen]

Just a little note on mpg since that is something we can compare in real terms. LS1/T56 combos are putting down mid to high 20's as far as mpg. That .5:1 6th gear certainly plays a role, but mpg of V8/6 speed is comparable or better than a L24/4 speed.

[CoastGuardZ]

Very very true! But, EFI vs. Carbs. Apples vs. Oranges. Not very fair. 25 years or so inbetween release date = 25 years of technological advances. How about fuel economy of an 70-72 camaro with a sb and it's power to weight ratio vs a the same #'s on a 70-72 240Z.

But then again we get into the fact the original question was not specific enough to state if "the" v8 Z transplant worth "it".

hmmm

Nate

[jmortensen]

Very very true! But, EFI vs. Carbs. Apples vs. Oranges. Not very fair. 25 years or so inbetween release date = 25 years of technological advances. How about fuel economy of an 70-72 camaro with a sb and it's power to weight ratio vs a the same #'s on a 70-72 240Z.

But then again we get into the fact the original question was not specific enough to state if "the" v8 Z transplant worth "it".

Fair??? Why is fair even an issue here? Fair to who? Both engines fit in a Z, one puts out 325whp and gets ~24 mpg, the other puts out 115whp and gets ~24 mpg. I'm sure if I owned the LS1 I'd think it was plenty fair.

[Fun_in_my_z]

Ok ive spent the last 20 minutes reading about number that i dont know a damn thing about.

Now as far as 150,000 miles on a 4.3. My daily driver is a 93 model saturn coupe. All origenal down to the stock battery. 277.000 + miles. Nothing but regular matanence.

At 40+ miles to the gallon. I put 20 in the tank and go for weeks. it has D/Ohc.

But on it best day it might would hit 85 MPH.

Ill stick to my L6