DMONTE

From where the spark plugs are located does anyone know if this engine is a hemispherical type engine? I can't find a detailed enough blowup of the engine to tell.

MY350Z.COM

iTrader: (2)

no

FLY BY Z

victor, no meaning you aren't sure? or you know for a hardened fact that you know that we do not have hemispherical combustion chambers? please cite your reference from where your combustion chamber shape knowledge stems. it is an interesting question to which I certainly hope the real answer is no. hemis make less power. marketing.

barrybell

"Hum less power" Mr. Potato Head, Let's go back to the 1960'S and talk about Plymouth Roadrunners 426 ci Hemi engines which made 426 bhp from the factory and because of the massive hp the federal government banded that engine "The Hemi".

Found this on the web

http://www.thehemi.com/engines.php?id=66ST426

FLY BY Z

Whooped dee doo. 426ci for 426 HP? How about Chevy's 302 putting out 390 HP? That is to name ONE. There are dozens of factory combos that put out gobs of power and punch for punch, the "hemi" was NOT the best. Are you going to rate a motor based on A) a website B) a government decision C) something that was hyped like crazy just like today? Maybe you are.

PS Click that link and check the weight of that inefficient overweight slob of a motor. You would need 400 HP to move the thing plus they were in boat-cars.

Silver Bullit II

The VQ35 does not have a hemispherical combustion chamber.

Z350Maniac

you have to keep in mind that back in the 60's technology was just springing to life. Now a days you can make engines lighter, stronger, run faster, rev higher, and tune them better with computers they didn't have that back then. Just putting some perspective on it all. I don't have an opinion on which is better.

little_rod

Got a hemi..............sweet.













Had to do that.

FLY BY Z

I agree with your statement which applies to the Chevy motors, Chrysler motors, Nissan motors, etc. The design of the combustion chamber is the basis here...

teh215

iTrader: (8)

I have to say that nobody in this thread yet understands what a hemi head is and do not understand the significance of the 426 Hemi. I would say that techically the 350Z heads are hemi heads... Hemi describes the relation of the intake and exhaust valves to the combustions chamber

menehune

Not sure about the VQ35 but the VQ30 has "hemi" heads. Well they look like in this picture:
http://www.overboost.com/pix.asp?ima...l/P1010073.jpg

I could be wrong though.

teh215

iTrader: (8)

That is pretty close to a true hemi. I would consider it more of a twisted chamber head for lack of a better term.

menehune

Oh, I forgot there was a posting of a pair of 350Z heads some time back. Here's the link:
https://my350z.com/forum/showthread....=cylinder+head

Vivid Racing

iTrader: (67)

actually, in the 60's when the hemi was the beat all of muscle car engines, the H/P rating was lowered from 510 to keep insurance rates low. you can say that it was marketing all you want but there's a reason that it's one of the most highly sought after engines in history and not to mention the most widely used in drag racing. The Hemi is the reason that Ford and Chevy came out with the Boss 429 and 454.

DMONTE

Why would this not be a modern hemispherical design?

FLY BY Z

It's all big block displacement.

DMONTE

I think I'm catching on, I was under the impression that the main idea of a hemi-engine was that the sparkplugs are centrally located on the dome but I find out that's not so I guess it's more about the consistent round dome then the central location of the plugs.

Thank you all for your input

Vash350Z

iTrader: (9)

the hemi head design is where the spark plug is in the center on the combustion chamber with the intake valves on one side and the exhaust on the other side, thus promoting better flow in the combustion chamber, from those pics, it looks like the VQ35 has a hemi head. my celica has a hemi head too *flex*, too bad its still slow

dr_gallup

Technically, the VQ35 is not a hemi because the intakes are parallel (exhausts are too). For a four valve engine to be a true hemi the valves need to be in a radial pattern with each one pointing in a different direction. Obviously, it is much simpler to make the valves parallel both from a machining and actuation standpoint.

The only true hemi four valve engine I know of was a Honda single cylinder race bike that used SOHC with wierd rocker arms all over the place. There probably have been other 4 (or 5 or 6) valve hemi race engines but the F1 boys don't let the public see their cylinder heads these days.

Back in the days of the original Hemi the competition was other low speed OHV pushrod motors. The Hemi's advantage was a compact combustion chamber with a central spark plug to minimize the the distance for flame propagation. We get much the same benifit with DOHC 4 valve heads and much better flow area for high RPM power.

AndyB

actually one of the main rationales behind the hemi was to minimize the surface area of the head (ie to contain the maximum vulume with the lowest surface area).

There is no magic about a hemi other than marketing at this point. With modern flow analysis and engine design there are many improvements beyond a simple hemispherical head.

I will admit that hemi still SOUNDS awesome though. Of course I was learning about cars starting in the late 70s when the hemis were legends.