Overhead cam VS pushrod design? Which is better?

[bemmerguy714]

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?

[jmortensen]

Hehe. I voted for OHC. I DO prefer it purely from a design perspective. When you translate that into L6 vs V8 you'll get a different result. I'm leaning away from OHC and towards OHV, because in the commonly available options, the OHC has a hell of a lot more hp potential.

Oops, that was supposed to say OHV has a hell of a lot more hp potential...

[bemmerguy714]

I also voted OHC cause i also think it has more potential for power. Not because anyone convinced me. I just did me own research on this. Both engines have potential. To me the one the can acheive it easier and safely for me would have to be OHC. OLd bimmers with overhead cam that where modded out could rev up to 9,000 RPM no problem. Thats not to mention new european and jap cars. Look at the supra, The skyline, the M3, the cl500, the 3 series!!!!!! Theres even a guy here who has a z (EricB) Who has built his head so that it can be reved up 8000rpm!!!! OHC seems to be easier to build with less things blowing up as uppose to OHV. For the weight issue i think OHC would also win cause it doesn't have the added mass of a pushrod.

Like i said before thou. I'm no mechanic. I've just grown on the OHC side of cars. I;m openminded thou. CONVINCE ME!!!!!! :laugh:

I put some links that argue both sides.

http://auto.howstuffworks.com/camshaft5.htm

http://www.classiczcars.com/forums/showthread.php?t=17606&highlight=8000rpm

http://www.datsuns.com/Tech/ohv_vs_ohc.htm

http://forums.autoweek.com/thread.jspa?forumID=9&threadID=16941&messageID=366730

http://townhall-talk.edmunds.com/direct/view/.ef61d1d/845

[260DET]

OHC for a more modern, powerful, lightweight engine. Not that a very good pushrod lightweight engine using modern technology couldn't be designed and built, they aren't though

[Aussie260z]

I remember reading somewhere that American Car makers

Invented the mass produced pushrod V8 to get rid of overly compliacted OHC engines, the pushrod V8 was the future :-)

[jmortensen]

OHC for a more modern, powerful, lightweight engine. Not that a very good pushrod lightweight engine using modern technology couldn't be designed and built, they aren't though

That's funny, I thought you in particular had a thing AGAINST the L6. Didn't you go RB just for that reason? Just out of curiosity what does the RB weigh, and how much $$$ do you have in your swap, and how much hp does it have. I'm betting that you could have done better with an LS1 swap.

For those who haven't yet seen it, here's the newest low tech POS: http://www.superchevy-web.com/technical/engines_drivetrain/completebuilds_testing/0504sc_ls7/

[CoastGuardZ]

For those who haven't yet seen it, here's the newest low tech POS: http://www.superchevy-web.com/technical/engines_drivetrain/completebuilds_testing/0504sc_ls7/

Ah yes, here's more of that good ol' "Big 3" thinking, - I know how to get more HP...let's just make a bigger engine!

[jmortensen]

Yeah, Nissan wouldn't do anything like that. It's not like they had the L16, then L18, then L20B, then NAPZ22 then NAPZ24, or the L20A, then L24, then L26, then L28, or RB20, then RB25, then RB26.

Too bad them good ol' Japanese get so caught up in bigger is better, eh?

[mriz]

I could be wrong but I thouht I saw an article that it's about $300-$400 cheaper to build a pushrod engine for the big three. I prefer ohc myselfe.

[auxilary]

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?

Does it matter how high the engine revs?

No.

Why not? Simple... cheap common production engines work like this: more displacement, lower redline. ie. Small block chevy 350 - 5500rpm redline, Honda Civic B16A2 =8-9000 rpm redline. You have to rev the wizz out of the civic motor to get power.

My Neon has a 2 liter dohc motor rated at 150hp. I get that 150hp at 6500rpm. My peak torque (all 133ft lbs of it) comes in at 5500rpm. That's a very not useful power band. Chevy 350 makes peak torque at like 2000rpm. Peak power at 5k. Much more useful configuration.

Will a chevy have a lower top end? no. Because a. it makes more power, b. it has different gearing. Everyone always ignores gearing!

Why are mustangs slower than they should be from factory? Because for put in something like 2.93:1 gearing in the rear pumpkin to retain fuel economy. That's why most ford guys swap'em out for 4.10s or 3.73 gears. BAM! instant improvement. Same reason we Z guys swap in 3.9/4.11 differentials to get more acceleration by sacrificing top end speed.

Another example: That honda civic si with hte dohc vtec motor that revs to 9k...has 4.42:1 gearing. That's why at 75mph, it "cruises" at 4000rpm! Drive an LT1 camaro with stock gearing and a 6 speed, and at 75mph you're turning about 1800rpm in 6th. And you can get 25-28 mpg on the freeway out of that v8

Returning to the question:

Which design is older?

in the following order:

flathead v8

ohc design

rotary

pushrod design

Is it worth the trouble?

You can do a v8 swap for under 2k. result would be a Z that's 150lbs heavier than stock and makes about 235-250hp and about 300-320 ft lbs of torque. Given the options, it's an easy sacrifice of power to weight, since it'd be like always having a passenger in your car.

IMO, a properly done v8 swap that includes an engine either as light as stock, or lighter than stock is a way to go for several reasons:

1. power. lots of it. cheap.

2. ease and cost of parts: chevy blocks have been made in same configuration since 1955, and ford about the same.

3. properly configured v8 swapped Z can handle better than an L-powered Z and weigh just as much or less

which engine style is better?

Depends what you want and how deep your pockets are. Here are some engines I've seen in person and on hybridZ people's profiles:

L24/26/28/L-stroker motor + turbo

L28 + supercharger off a grand prix SC

L28 twin turbo

LC2 (buick grand national turbo v6)

SBC 305/350/355/383/LT1/454

LS1/LS6 and someone just bought an LS2 (new gto)

Ford 5.0/289/351

BMW I6/V12

Jaguar V12

Turbo Diesel L28

Electric Z

Rotary (that would be me)

SR20DET

RB20det/RB25det/rb26dett

426 hemi

360 mopar

viper v10

and a lot more I can't think off top of my head

What would I prefer? If I had to do it over again, I'd do an LS1

[CoastGuardZ]

Alright - point taken fellas, but you should look at it from other stand points. These Z's are classic sports cars that really changed the motoring world...

You wouldn't slap a 426 Hemi in 67' Z/28

Just like you wouldn't pop a Chevy 327 in a '65 Mustang GT

But hey why not- they make more power don't they? It's not the point. We're talking about tossing bigger engines in a chevette here.

Also, I don't think there is a VQ70 anywhere in Nissan's future. More power to legitametly over come emissions and heavier vehicles make's since, does it not? I don't recall the C6 being like 1000 pounds more than a C5, and I don't see it pulling trailers in the future... oh maybe it's to try a go at the Ford GT. Which Ford left at a smaller output and S/C instead. Whatever this could go for days... I just don't understand the idea of killing a classic regardless of it's make. And I also know that my '72 Z looked pretty damn cool being trailered by my NISSAN Frontier when I moved up here.

Nate

True-Blue

[auxilary]

sbc powered mustang

give me some time and I'll find you a hemi camaro

Who said anything about bigger engines? mine's a 1.3 liter!

I was thinking of going to the junkyard, finding a datsun 310, and making a 130Z badging for my car