3100 top end swap??

[editface53]

can i just get the top end of a 3400 and put it on my 3100 sfi? as in top end i mean upper and lower intake manifold and a 62mm TB. what will i gain from that if it will even work?

[alpinestar10]

What year 3100 do you have? If its 99+ i think it should be the exact same swap think the lower might even be the same as in the heads

[bszopi]

On your upper manifold, does it say 3100SFI in big letters and otherwise smooth? If so, then its the exact same as the 3400. If it says 3100SFI in smaller letters and is surrounded by raised lines on the manifold, then you would benefit from a top end swap.

[editface53]

yeah it has the raised lines...so i would gain something from the swap
?? and would i have to change anything else to get the most out of it. i have a intake on already..so anything else else besides that to get full potential?

[steve-0]

I have a 96 3100 Sfi small port with the eased lines. If I were to switch it to a2000 3400 intake how much should I gain. And should the heads off that motor de a upgrade as well with out having problems. I don't have access to tunning software.

[Merc6]

LG8(newer 3100) and LA1(3400) heads flow better than the L82 we have. For the Centuries, it was 2000 and up for the LG8 but 99 they only converted the airbox and over flow tank. Your rockers might need to be changed or modifications to the LIM for clearance on the intake swap. If you do heads, the rockers shouldn't be an issue anymore. I was going to do the whole top swap but I chickened out. Got just the LA1 intake, throttle body, coolant overflow, air box, and zip tube waiting of the time and funds for the gaskets and fluids. I might do the LA1 throttle while I wait for the full swap. You would also need the head gasket and LIM gasket set for the 3400. The UIM doesn't bolt up the same. Reason you have to swap the entire intake vs just the top half.

[steve-0]

ok, i have all the gaskits and fluids ready, but how much power would i get from an intake swap, and how much power would it be with the heads and intake swap, ball park it please, and ill do the swap if its worth it, also whould i need to change the programing in the stock comp?

[robert 1980]

I would guess 15 to 20 more hp.I have a whole topend for sale if you wanted?Off of my 2003 3400 with 60xxx miles.
Like any peformance mod tuning always helps.Im selling it cheap so let me know

[Merc6]

IIRC no. You can use stock computer settings but you can get better results with a tune. Even stock you could get results from a tune.