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#150106 - 09/22/02 09:46 PM 3.8 vs 3800
gary Offline
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Registered: 08/26/02
Posts: 181
Loc: San Diego
What's the notable differences between the earlier 3.8 litre engines, and the 3100 designated engines?

Gary in Sandy Eggo
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#150107 - 12/21/03 06:23 AM Re: 3.8 vs 3800
Paul Offline
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Registered: 12/17/03
Posts: 18
Loc: Island Co. WA, USA
~700cc's. smile

Which 3.1? GM has made several.
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#150108 - 12/22/03 02:08 PM Re: 3.8 vs 3800
Bryan R Offline
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Registered: 02/08/03
Posts: 309
Loc: Portland
For starters, the 3.8 has a 90 degree bank angle, the 3100 has a 60 degree bank angle. 60 degrees is supposed to be the optimum for a V6, which is why it doesn't need balance shafts like the 3.8, because it was really a V8 in its former life. 90 degrees is optimal for a V8 engine.

The early 3.8 engines were odd firing, but in the early 80's, GM changed it to even firing.
The 3100 is a sequential firing order (1-2-3-4-5-6).

The early 3.8 engines were the first to get tuned sequential port fuel injection. At the time of the Series-I 3.8, the 3.1 engine, (which was 2.8 litres at the time) only had multi-port fuel injection. Basically at the time the 2.8/3.1 engine all the injectors fired at the same time, but the 3800's injectors only fired when the intake valve opened, (or slightly before). But I think currently all GM's engines have SPFI.

Basically all the "high-tech" stuff got developed on the 3.8 first, and later applied across the board on other engines. Like the roller rockers, micro-finished cylinder walls, etc.

Hopefully I interpreted your question correctly. All this information was retrieved from gmpowertrain.com a few years ago, when I used to argue with people why DOHC engines are NOT automatically higher tech than OHV engines.

cheers

bryan
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#150109 - 12/22/03 03:45 PM Re: 3.8 vs 3800
Paul Offline
Junior Member
Registered: 12/17/03
Posts: 18
Loc: Island Co. WA, USA
Actually, the 3.8 got the even fire hardware hardware in mid-'77, two years after GM bought the tooling back from AMC. (They had sold the Buick V6 tooling to AMC/Jeep in 1969 or 1970.) When GM first put the 90 degree V6's in their FWD cars, they had a 3.1L version as well as the 3.8L. The current 3.1's are based off of the 2.8L and there's also a 3.4L. There's also a DOHC 3.1L 60* V6 that was developed from the 2.8 family. In both the 2.8L family and the 3.8L family there are FWD and RWD/4WD variants and due to block differences, most parts don't interchange between their drive varaints.

I've got a '71 Jeep CJ-5 that came with a 225 (3.7L) V6 and researched my options before deciding it was most cost effective to get more power by swapping in a V8. I've also got an '86 Cherokee that came with a 2.8L GM V6 and is getting a SFI 3.4L from a '94 Camaro. I've also got a couple of FWD 2.8L's hanging around collecting dust/rust... anyone wants them, they can have them, free.
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#150110 - 12/22/03 05:48 PM Re: 3.8 vs 3800
Paul Offline
Junior Member
Registered: 12/17/03
Posts: 18
Loc: Island Co. WA, USA
I noticed the original post is titled 3.8 vs 3800, then in the text, it asked 3.8 vs 3100... if it is actually about the 3800, I believe the only difference is the term.
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#150111 - 01/15/04 03:02 PM Re: 3.8 vs 3800
EnYgMa Offline
Member
Registered: 05/05/02
Posts: 268
Loc: Edmonton, Alberta, Canada
Hi Paul,

What year are the 2.8 FWD's you have? How many miles on them? And hell(!!), if you're giving them away for free, how much would shipping be to Canada?!?!
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#150112 - 02/15/04 04:28 PM Re: 3.8 vs 3800
Gozilla Offline
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Registered: 05/25/03
Posts: 40
Loc: houston,tx
what! confused confused
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#150113 - 02/18/04 05:02 PM Re: 3.8 vs 3800
EnYgMa Offline
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Registered: 05/05/02
Posts: 268
Loc: Edmonton, Alberta, Canada
What, what??
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Krishna Tailor, BA BAMPA
The FALCON -> White GTP Coupe
FWI, 3.4", AMSOIL Oil/ATF, Tint, SS Grills
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#150114 - 02/18/04 05:26 PM Re: 3.8 vs 3800
Gozilla Offline
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Registered: 05/25/03
Posts: 40
Loc: houston,tx
exactly! next topic please? darthvader
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#150115 - 02/21/04 03:27 PM Re: 3.8 vs 3800
Adam S. Offline
Member
Registered: 02/19/04
Posts: 678
Loc: Milwaukee, Wi
I'm not sure, but I think he meant the difference between a 3.8 and a 3800. If this is so, it was mainly just a different name to put on the engine cover. Yes, the 3.8 has changed numerous times over the years, but at one of those years, they just decided to call it 3800.
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#150116 - 02/22/04 10:22 PM Re: 3.8 vs 3800
Gozilla Offline
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Registered: 05/25/03
Posts: 40
Loc: houston,tx
now i understand! :p
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#150117 - 04/15/04 11:40 PM Re: 3.8 vs 3800
Jizz Offline
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Registered: 03/22/04
Posts: 766
Loc: Central Maryland
This is how I feel after this thread crazy
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#150118 - 04/16/04 06:33 PM Re: 3.8 vs 3800
Gozilla Offline
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Registered: 05/25/03
Posts: 40
Loc: houston,tx
you forgot this one... banghead
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#150119 - 05/13/04 07:21 PM Re: 3.8 vs 3800
pgp2000gt Offline
Member
Registered: 01/03/04
Posts: 157
Loc: Carstairs, Alberta, Canada
no no no no no. the 3.8l is technically the older 231 and 229 cu in. V6's in the rear drive chevys and buicks (70's-80's). the 3800 is the late 80's-early 90's 60 degree v-6 in the front drive buick and pontiacs. It was the Series I, only it wasn't called that back then, cuz there was no immediate plans for a series II or III. yes it is 3.8l, but it is wrong to call it so, 3800 is correct.
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#150120 - 05/13/04 07:55 PM Re: 3.8 vs 3800
Jizz Offline
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Registered: 03/22/04
Posts: 766
Loc: Central Maryland
GO 3800 GO!!! hammer
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