How does a 90 degree V-6 work?
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
How does a 90 degree V-6 work?
How'd Chevy get away with a motor that doesn't have a balanced firing order? I would think the V6 would have to be 120 degrees.
There's gotta be two deadspots in the firing order. Seems that would be difficult to balance or rev high.
3 power strokes per revolution, but two of those strokes will have to be 180 degrees apart.
So does a 3.8L run as well (or as badly) as a 5.7L with two dead cylinders?
There's gotta be two deadspots in the firing order. Seems that would be difficult to balance or rev high.
3 power strokes per revolution, but two of those strokes will have to be 180 degrees apart.
So does a 3.8L run as well (or as badly) as a 5.7L with two dead cylinders?
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Ahh the miracle of google.
The crank throws have a "splay angle" on them. Same for flat-6's. There is essentially a seperate throw for each cylinder, not paired up like our beloved v8.
Without splayed throws, like on a 90* V8, the block angle has to match up with the angle of firing. A V8 could be made flat or 90* with non-splayed throws... but I guess it's not balanceable.
A V6 would have to be 120* if not for splayed throws.
Here's some good reading:
http://www.autozine.org/technical_sc...ne/smooth1.htm
Here's a splayed throw.
The crank throws have a "splay angle" on them. Same for flat-6's. There is essentially a seperate throw for each cylinder, not paired up like our beloved v8.
Without splayed throws, like on a 90* V8, the block angle has to match up with the angle of firing. A V8 could be made flat or 90* with non-splayed throws... but I guess it's not balanceable.
A V6 would have to be 120* if not for splayed throws.
Here's some good reading:
http://www.autozine.org/technical_sc...ne/smooth1.htm
Here's a splayed throw.
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
What does the crank on a 3.8L look like?
Very different from the 350 crank. And I wonder if the connecting rods or pistons are offset a little too because the rods cant be put as close together.
Very different from the 350 crank. And I wonder if the connecting rods or pistons are offset a little too because the rods cant be put as close together.
Last edited by CentralCoaster; Jan 26, 2006 at 04:25 PM.
Le Mans Master
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From: Modesto CA
Originally Posted by CentralCoaster
What does the crank on a 3.8L look like?
Very different from the 350 crank. And I wonder if the connecting rods or pistons are offset a little too because the rods cant be put as close together.
Very different from the 350 crank. And I wonder if the connecting rods or pistons are offset a little too because the rods cant be put as close together.
BTW: I dunno about them 3.8L's but they sure are fast!
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Aren't the Chevy V6s even fire? That is that all cylinders fire an even number of degrees apart? I'm thinking that the Buick V6 is the odd fire engine. I used to work on a lot of these but it's been a goodly number of years ago. Back in the 50s and 60s GMC trucks had an odd fire V6 of large displacement. I remember a 401 among other sizes. They were some serious torque-making bastards.
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St. Jude Donor '15
"In honor of jpee"
Originally Posted by jfb
Ever sit in a V6 car idling and not have it shake? I haven't.
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From: The Top of Utah
I don't know if they are still made this way or not, but the original 231 CID Buick (3.8L) used a V8 distributor cap with only 6 wires installed. THAT is evidence of an odd fire engine.
The 4.3L Chevy, 90°, V6 is essentially a 350 V8 with cylinders 4 and 5 removed. Unlike the Buick, the Chevy's offset, Siamesed, crank throws allow for an even firing order, in a 90° block.
RACE ON!!!
The 4.3L Chevy, 90°, V6 is essentially a 350 V8 with cylinders 4 and 5 removed. Unlike the Buick, the Chevy's offset, Siamesed, crank throws allow for an even firing order, in a 90° block.
RACE ON!!!
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Ahh, that is a good indicator! Nothing seems to go over CFIs head. I guess if the whole world was made up of gearheads and engineers, there'd be no one left to pick up the trash or clean the toilets.
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From: Director of Bands
St. Jude Donor '08
Originally Posted by LT4CompYell
Shake? Really? To answer, yes, I have sat in V6 cars and there's no shake. Maybe it's unique to 3.8GMs, but I've sat in those, too. Don't recall shaking at idle. I've also sat in Acuras, Infinitis and Lexus V6s, no shake that I recall. Could be mount dampening tho.
What's this shaking at idle? My truck and my Vette are the only cars I've owned that did not have the 3800 V6 (I love that motor!)... and I have never experienced this shake at idle. Not in the Gen I or Gen II motors. Might be a good idea to check your motor mounts...
Racer
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From: La Grande Oregon
The 4.3 in my 93 forest service crummy has a balance shaft up by the cam and lifters, since i haven't looked to make sure it's for the crank i will guess thats what it's for,.....untill spring when it (the 4.3)comes out to get freshened up. ... 
Team Owner
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From: San Pedro CA
Didn't the Gen II 3800 add the balance shaft?
The old Chevy 2800, 3100, 3400 and now 3900 is a POS... I guess it has gotten better, but gee, the older versions were as nasty as they come.
I do like the 3800 Buick, tho. That is one sweet little motor.
The old Chevy 2800, 3100, 3400 and now 3900 is a POS... I guess it has gotten better, but gee, the older versions were as nasty as they come.
I do like the 3800 Buick, tho. That is one sweet little motor.
