mercruiser 454 exhaust riser questions

[phatmanmike]

hi. i am in putting my 454s back in the boat after rebuilding the starboard motor. anywho......

1989 baja 320 twin 454's 375hp bravo 1's.

my old exhaust rusted through and i had to rebuild starboard engine. i have them mostly back and ready to go. i have tossed my old exhaust elbo's/ risers and have a wierd question:

[

i have a set of 8 " risers and a set of 10" risers , the round tubular style they use on HI-PO big blocks like the 496's. what SNAFU would i run into if i used the 10"er's on one motor and 8" on the other motor? can i run them like this untill i get enough money for a nother set of matching risers?

im just thinking outside the box.......

 

[Bondo]

Re: mercruiser 454 exhaust riser questions

Ayuh,........

As long as you have Atleast the required 13" of height above waterline,+ can get everything Attached,..........

I really don't see a problem..........

I've got a Sweet set of Polished SSteel 1s for My 4.3LX next spring.......

 

[HT32BSX115]

Re: mercruiser 454 exhaust riser questions

Ok,

Mike, now that you got your question answered.......How are your 454's rated at 375hp? They're carb'ed right? (or are they EFI?)

Are you REALLY getting 375hp from 87 octane pump fuel?


Thanks,


Rick

 

[phatmanmike]

Re: mercruiser 454 exhaust riser questions

im guessing from the other mods that have been done. and from the speed that the boat went before the stbd motor rusted shut.

boat went tops of 71 via GPS.

they also had edelbrock aluminum manifolds, aluminum roller rockers, bored .040 over, custom holley 750's, hi power mallory ignition . i didnt do the mods myself, but i knew the previous owner and knew of what he had done to the boat.( i just got the boat this month)

after i finish upgrading the exhaust with the 496HO 10" risers and aluminum EMI manifolds from www.eddiemarine.com , im hoping to pass the 400hp mark.

i dont see why 400hp on pump gass from a 454 bored .040 over is such a weird thing.

anywho... thanks

 

[HT32BSX115]

Re: mercruiser 454 exhaust riser questions

Well thanks for the info. Be sure to post your performance numbers and pictures here.....

We love pictures and and performance specs!!


Cheers,



Rick

 

[phatmanmike]

Re: mercruiser 454 exhaust riser questions

wil do. thanks for the responses.

by the way. i took this thing as a trade. i traded a 1977 TROJAN fbmy F28 w/ twin 351 v-drives. i took THAT thing as a trade from a 1984 MAKO 20c center console w/ 1994 merc 200hp.

so, i went from a 20' mako, to a 28 ' trojan, to a 32' baja. im trying to work my way up to a 110' hateras! HAHAHA

and i dont have a penny into anything yet, since it was all trading!

mike