Camshaft upgrade on a 5.7 w/tbi

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silvert

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Sorry for another thread, but I've decided on what longblock I'm going to use in the '99 Rinker 232 BR I just bought with a cracked 5.7 TBI. GOing to get a GM Goodwrench 5.7 vortec. Before I throw it in there, I'm thinking of upgrading the cam. Been researching on here and elsewhere. Thinking of possibly the 350 ramjet cam, this one http://www.compperformancegroupstor..._Code=CC&Product_Code=08-416-8&Category_Code= or this one which is a little more aggressive http://www.compperformancegroupstor..._Code=CC&Product_Code=08-417-8&Category_Code=. Been reading this thread http://forums.iboats.com/forum/engi...r-to-a-vortec-5-7l-and-possibly-a-383-stroker. He has a Volvo with a tbi, non vortec. Mine is a Vortec Mercruiser. Will I need to reflash the tbi with just a cam upgrade? I will probably replace the valve springs too.
Last thing, How much power can a Bravo 3 handle?
TIA
 
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silvert

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Looks like the needed valve spring for these cams will not work w/o machining on the head. The spring have a .697 id and the od of the valve guide bosses are around .845.
 
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silvert

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stock cam for the gm engine is:

.418"/.428" lift

191/196 duration @ .050


the smaller comp marine cam is:


.488"/.495" lift


212/218 duration @ .050

This upgrade, with the ls6 springs and comp retainers is about $400.

Will the TBI work or will it need a reflash? Will the stock tune work for now and retune later for max gain?
 
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alldodge

alldodge

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If you increase the cam and don't increase the compression you will have a turd for a motor, same thing if you go the other way around.

Standard B3 can handle 400HP, the XR is 500HP yet Merc puts them behind 525's. Many are running twins pushing 625HP. The B3 is a B1 upper and 3 lower. The XR is a B1XR upper and standard B3 lower. It's torque which breaks the drives not HP. Your 232 is a light boat, so if you don't go airborne and come back in at full throttle you will be fine.

Another point is the B3 is go for around 50MPH when your going to have the B3 start slowing you down. Be that as it may your working with a 5K pound boat
 
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silvert

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The compression for the new gm engine is 9.4:1 where it looks like the stock mercruiser is around 9.1:1
 
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silvert

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Yeah I know what a cam does, trying to point out that the one in the engine I'd like to buy has a lot less duration and lift than a stock mercruiser cam. Not wanting to under power the boat, I'd like to replace it. These vortec engines with 9.x:1 compression ratios, stock unported heads, respond very well to cams with more duration and lift. With the right spring and retainer, one can go to..500" lift without additional machine work to the head. My question is, how does the stock tune in the tbi ecm respond without a new tune.
 
Faztbullet

Faztbullet

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That's not a performance hull and the xtra hp aint going to add much to top end unless you raise drive x deminsions.
 
Watermann

Watermann

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Good choice on the stock cam with the TBI. The TBI set ups on 5.7's with the 60# fuel injectors do not play well with a higher lift cam which plays heck with their need for stable vacuum. I know this from the auto world, most guys wanting more by way of camshafts in their trucks end up wasting money and going back to stock RV type cams.
 
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