FAQ  •  Login

5-valve-head vs 4-valve with VVL?

<<

TurboJ

User avatar

Posts: 366

Joined: Mon Jul 20, 2015 3:01 am

Cars: Alfa Romeo 75, Ford Puma

Post Tue Sep 29, 2015 2:56 am

5-valve-head vs 4-valve with VVL?

Has someone analyzed which configuration gives the best end results? Especially when looking at turbocharged eco and sports engines where you want to have
high specific output but still a broad torque curve. Do you get the broadest torque curve with 5 valves or 4 valve with VVL (seeing as you can't have VVL with 5 valves currently)?
I realize I could test this myself but there are so many variables I'd like to hear from what others have found about this first. Thanks!
Image

J.S.C Automobili S.p.A - Exclusive sports cars since 1959
J.S.C Motori Speciali - My open-source performance engines
Patriot Motor Force - 'Murican Evolutionary muscle cars

My Engine Tuning Video Guides
<<

nialloftara

User avatar

Supercharged
Supercharged

Posts: 1983

Joined: Wed Feb 05, 2014 2:07 pm

Location: Northeast USA

Cars: 2006 Scion Xb

Post Tue Sep 29, 2015 4:44 am

Re: 5-valve-head vs 4-valve with VVL?

4 valve vvl has a broader range but 5 valve has better airflow and less weight per valve which allows higher revs and more top end power. In terms of just economy I'd say it goes 4 valve-5valve-4valve vvl. After that its mostly user's preference as there are pros and cons between vvl and 5valve, like reliability, weight, service costs, torque, economy... Its about what kind of character you want your engine to have.

Edit
VVL also has plenty of variation just in itself, you can have a very abrupt kick in or you can make a broad smooth curve. If you are looking for a economic turbo car I'd say vvl, you can get nice flat torque curve with the right set of cams, and turbo setup. 5 valve turbos can make lots of top end power but with more lag, it's a lot harder to make the turbo both spool quick and still rev high with only 1 can profile.
Chief designer and CEO, Centauri motor works, Centauri Performance Vehicles (CPV)
"Centauri: The Stars Are Within Your Reach."
Centauri engines Centauri cars
CPV engines CPV cars
Company ID: 1943047
<<

vmo

User avatar

Naturally Aspirated

Posts: 1178

Joined: Wed Jul 04, 2012 4:29 am

Location: Spain

Cars: A undestructable Toyota with 1ZR FAE engine, Honda Civic VTi EG6, Mazda RX7 fc

Post Tue Sep 29, 2015 9:22 pm

Re: 5-valve-head vs 4-valve with VVL?

5 valve: recommended for race engines that doesn't had much power and torque at bottom RPM, and is designed to perform at high RPM.

4 valve+ VVL: recomended for road cars, because you can select 2 cam profiles to make a smooth, progressive and a flatten torque and lineal power delivery at all RPM.
Company: Montes Cars
Company ID: 1940001
Visit the brand models http://automationgame.com/phpBB3/viewtopic.php?f=35&t=3995
In AutomationHub.net: http://www.automationhub.net/company-ca ... mpanyID=18
My YouTube Channel: https://goo.gl/1MtRpd

Return to General Chat

Who is online

Users browsing this forum: No registered users and 0 guests