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interchange info on intake & heads 2.8 to 3.1 v6's

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  • interchange info on intake & heads 2.8 to 3.1 v6's

    Hi I have a supercharger and intake made for the 2.8 chevy v6 . The iron head 2.8 truck motor. I'd like to use it on the 3.1 engine for a little bigger motor. They say the 2.8 and 3.1 engines are the same engine but from my look see at a junk yard they look different. The 3.1's intake looks a lot wider and the heads look different. Will these intakes or heads interchange or maybe you have to use the 2.8 heads to get the 2.8 intake to fit the 3.1. Thanks for the help

  • #2
    The answer as you might guess is "that depends". The FWD and RWD motors are different. Both the gen 1 iron head motors and gen 2 aluminum head motors were labeled 2.8L and 3.1L. If you have a 3.1L truck crank and pistons I think you could swap them into a 2.8L truck block easily. But, I would probably look into an F-Body 3.4L if I were you and wanted to stay with a gen 1 iron head motor. Here is how I remember the gen 1 displacements 2.8L (original) 3.1L (more stroke) 3.4L (3.1L stroke with more bore). This isn't and exhaustive look at the differences but it will hopefully point you in the right direction. Good luck and have fun!

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    • #3
      Originally posted by neophile_17 View Post
      The answer as you might guess is "that depends". The FWD and RWD motors are different. Both the gen 1 iron head motors and gen 2 aluminum head motors were labeled 2.8L and 3.1L. If you have a 3.1L truck crank and pistons I think you could swap them into a 2.8L truck block easily. But, I would probably look into an F-Body 3.4L if I were you and wanted to stay with a gen 1 iron head motor. Here is how I remember the gen 1 displacements 2.8L (original) 3.1L (more stroke) 3.4L (3.1L stroke with more bore). This isn't and exhaustive look at the differences but it will hopefully point you in the right direction. Good luck and have fun!
      How are the fwd & rwd different , well other than how the motor sits and motor mounting differences? I would think they would use the same mounting pattern & spacing for bolts on intake and also heads on either type of motor. As always my luck is not very good, the supercharger and intake are from a rwd 2.8 truck the 3.1 engine I found cheap is out of a 94 Corsica fwd. I bought the whole car and was thinking of putting the supercharger on the car for the summer just to play with. It would take some changing things around to get it to work, mostly relocating the motor mount and power steering pump but It looks like it might be possible. I was hoping not to have to rebuild the motor just slap the intake and supercharger on engine. Those motors an transmissions are cheap enough I could always buy anther if I blew them one up.
      Last edited by turbotim23; 03-18-2016, 03:51 PM.

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      • #4
        Originally posted by turbotim23 View Post
        How are the fwd & rwd different , well other than how the motor sits and motor mounting differences? I would think they would use the same mounting pattern & spacing for bolts on intake and also heads on either type of motor. As always my luck is not very good, the supercharger and intake are from a rwd 2.8 truck the 3.1 engine I found cheap is out of a 94 Corsica fwd. I bought the whole car and was thinking of putting the supercharger on the car for the summer just to play with. It would take some changing things around to get it to work, mostly relocating the motor mount and power steering pump but It looks like it might be possible. I was hoping not to have to rebuild the motor just slap the intake and supercharger on engine. Those motors an transmissions are cheap enough I could always buy anther if I blew them one up.
        The 94 Corsica had the small port 3100... there will be no simple slapping of intakes and power adders. Head swaps and a lot of dicking around is what you'll be doing. The intake manifolds are most definitely not cross compatible. The ports are nowhere near the same size/shape.
        Last edited by carbon; 03-18-2016, 08:43 PM.
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        • #5
          History lesson time:

          To start with there's no "truck 3.1". The RWD 3.1 was only offered in the F-body (Camaro and Firebird). The S-10 only ever had the 2.8 from the 60 degree V6 engine line, They were also all iron head. All RWD 60 degree V6s were iron head for that matter.

          The FWD 60 degree V6s changed much more over the years. In 1987 the FWD 660 was changed from iron head to aluminum head, which are a very different design and the intakes will not swap. Starting in 1991 in certain car lines the gen3 was introduced. There was over lap of gen2 and gen3 up to 1994, when the last gen2 660s were installed in the Cavalier. While the gen2 and gen3 heads look very similar to one another again the intakes will not swap, due to some port shape and size changes.

          There are changes in the blocks between FWD and RWD that make them not directly interchangable, like starter locations and the front engine pad mounst that are different over the years and generations.

          Anyway. to use the Fagoel supercharger you have you will need to install iron heads on the engine you have, but there's a problem here, due to the combustion chamber size differences between the iron head and aluminum heads the static compression ration drops, a lot, like down to 7:1 or so, which may sound like a good idea for boost, but it's not. It makes for a terrible inefficient engine off boost, sluggish and will (likely) have terrible gas milage So in order to use the iron heads, you will also have to swap pistons to get the SCR back up to around 9:1 (IIRC the RWD 3.1 was about 8.9:1 SCR). After going trhough all of this you will have an engine that produces somewhere around 200 HP, maybe less. An easier way to get 200 HP in your Corsica is to drop in a 3400 from a Venture or Impala, and with some proper tuning has been known to put out 200 HP. Another option that will take a little more work than the 3400 is the 3500 (LX9) that starts with an SAE rated 205 HP, and has been known to put out more than that with a good tune in stock form. Both the 3400 and even 3500 will be less work for better pay off than trying to use that Fagoel supercharger. Both engines will also fit under the hood of the Corsica, where as the Fagoel will not.
          James: 1985 GMC Jimmy, 3.2L turbocharged, intercooled hybrid 13.873 @ 99.08 218HP & 270FT/lbs @ the wheels
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          • #6
            Originally posted by The_Raven View Post
            History lesson time:

            To start with there's no "truck 3.1". The RWD 3.1 was only offered in the F-body (Camaro and Firebird). The S-10 only ever had the 2.8 from the 60 degree V6 engine line, They were also all iron head. All RWD 60 degree V6s were iron head for that matter.

            The FWD 60 degree V6s changed much more over the years. In 1987 the FWD 660 was changed from iron head to aluminum head, which are a very different design and the intakes will not swap. Starting in 1991 in certain car lines the gen3 was introduced. There was over lap of gen2 and gen3 up to 1994, when the last gen2 660s were installed in the Cavalier. While the gen2 and gen3 heads look very similar to one another again the intakes will not swap, due to some port shape and size changes.

            There are changes in the blocks between FWD and RWD that make them not directly interchangable, like starter locations and the front engine pad mounst that are different over the years and generations.
            Anyway. to use the Fagoel supercharger you have you will need to install iron heads on the engine you have, but there's a problem here, due to the combustion chamber size differences between the iron head and aluminum heads the static compression ration drops, a lot, like down to 7:1 or so, which may sound like a good idea for boost, but it's not. It makes for a terrible inefficient engine off boost, sluggish and will (likely) have terrible gas milage So in order to use the iron heads, you will also have to swap pistons to get the SCR back up to around 9:1 (IIRC the RWD 3.1 was about 8.9:1 SCR). After going trhough all of this you will have an engine that produces somewhere around 200 HP, maybe less. An easier way to get 200 HP in your Corsica is to drop in a 3400 from a Venture or Impala, and with some proper tuning has been known to put out 200 HP. Another option that will take a little more work than the 3400 is the 3500 (LX9) that starts with an SAE rated 205 HP, and has been known to put out more than that with a good tune in stock form. Both the 3400 and even 3500 will be less work for better pay off than trying to use that Fagoel supercharger. Both engines will also fit under the hood of the Corsica, where as the Fagoel will not.
            Thanks I was pretty sure the only way to get the intake to fit was by using the iron 2.8 truck heads, didn't know about the compression drop though. I was unsure How well the iron heads would work though. I was getting ready to fix a head gasket leak and now was the time to decide if it was possible. This tells me it might be better to use the blower on anther of my cars. I'm lucky in that I bought one of the last remaining adaptors to be able to mount this blower to any standard 4 barrel intake, so I can use it elsewhere.. It'll probably be my 73 duster with a slant/six. It might get more respect in that car anyway. Thanks again
            Last edited by turbotim23; 03-19-2016, 03:22 PM.

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