Fast Rev Engine...How and what does that mean?
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Melting Slicks
Joined: Jan 2003
Posts: 2,713
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From: Shreveport LA
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Fast Rev Engine...How and what does that mean?
I'm going to ask a silly question..."How do certain engines rev so quickly?" My wife's BMW 2.5 Z3 revs really fast and the pick up is fantastic! ...and it's only a 6 cylinder!!
Now my 350/300hp revs not as quick from idle (1000 rpm) to cruising 2500 rpms. BUT from 2500 -4000rpms the revs come quickly as well as the acceleration.
I just read Chevy is coming out with the new Z28 Camaro and will have the same fast reving engine (I'm assuming the 302) as the 69 Z28 Camaro.
So what makes an engine a "Fast Rev" engine? And what is the best way to Always heard the terminology...didn't know exactly what that meant.
Now my 350/300hp revs not as quick from idle (1000 rpm) to cruising 2500 rpms. BUT from 2500 -4000rpms the revs come quickly as well as the acceleration.
I just read Chevy is coming out with the new Z28 Camaro and will have the same fast reving engine (I'm assuming the 302) as the 69 Z28 Camaro.
So what makes an engine a "Fast Rev" engine? And what is the best way to Always heard the terminology...didn't know exactly what that meant.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The newZ28 engine is not even anywhere near the old Z28 engine. Nothing is even close. I'll take the new one over the old dog 302 anytime. The old 302 was a road race engine and not designed to to run low rpm. Yes it would rev but from an idle is was a dog. The new LS motored Z28 is a totally different animal. As far as reving the engine light flywheels and modern tech goes there is no comparison between old vs new tech.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
The new Z28 has a LS7 in it, it is a 4.125 bore X 4.00 stroke not exactly the same bore/stroke as a 302 Chevy @ 4.00 bore X 3.00 stroke. Having owned both a C6 Z06 (LS7) and various 68/69 Z/28 Camaros, I can tell you the LS7 revs up pretty fast but, it's torque is what gives it 11second quarter mile times where my old 2X4 Xram 302 Z/28 was pretty "doggy" in its performance.
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
Quick revving, out of gear, is typically a product of rotating weight (crank, pistons, rods, flywheel). A lightweight flywheel is going to "buzz" quicker than a heavy one. The 45 lb flywheel in my 83 F-250 4x4 was a real slow revver. The 20# flywheel in my 78 is pretty quick.
LS7s have pretty hefty pressure plates, and the whole assembly is quite a bit of mass. Just going to a lighter clutch kit will drop the mass by a lot. It's been a while since I've been up on this, but I'm told an LS7 pressure plate and clutch with a billet steel flywheel weighes about as much as an LS1 clutch kit with an iron flywheel (maybe a bit less).
I don't frequently hear the term "fast rev engine", but it would make me think of a car with a lightweight flywheel and clutch.
It's worth noting that a lighter rotating assembly comes with its own disadvantages (harder to launch without stalling, etc).
LS7s have pretty hefty pressure plates, and the whole assembly is quite a bit of mass. Just going to a lighter clutch kit will drop the mass by a lot. It's been a while since I've been up on this, but I'm told an LS7 pressure plate and clutch with a billet steel flywheel weighes about as much as an LS1 clutch kit with an iron flywheel (maybe a bit less).
I don't frequently hear the term "fast rev engine", but it would make me think of a car with a lightweight flywheel and clutch.
It's worth noting that a lighter rotating assembly comes with its own disadvantages (harder to launch without stalling, etc).
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
It sounds like you have a little bit of a hot cam in your 350. Quick revving has a lot to do with reciprocating mass being lighter.
The new Z28 will crush the wife's car!
The new Z28 will crush the wife's car!
Last edited by hugie82; Mar 29, 2014 at 10:22 AM.
