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My motor 2..specs and recs estimated MPH?

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BOSTONCAMARO

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Discussion starter · #1 · (Edited)
Ok

I appreciate the input on my motor..

This is what I want, I want it to be fast, I want to run a wet exhaust similar to BARR center dumps.

This is what I have for parts so far but of course can get some stuff, the idea is to do this swap as cheap as possible but yet be dependable and hopefully fast.

350 4 bolt main 30 over

steel forged crank

Cam 455 lift 296 duration 114 lob seperation if not this cam, what would you guys run?

1987 Corvette alum heads 194 and 150 valves

Full roller rockers

Edelbrock Performer and Edelbrock Performer RPM intake

11 to 1 pistons as well as 10 to 1 pistons

Several Holley carbs from 600 up to 1000 cfm

Also what do you think it can run optimally, once the drive gears are changed, right prop etc in a 17 foot v hull Glasstream?

Thanks, Tim
 
Discussion starter · #4 ·
birdog said:
Rare....Rare....Rare !.... :D
Click to expand...
I take it they are not hard to come by, that is tongue in cheek?

I am new to modifying a boat, so please advise

my dad is going to look at manifolds and some other parts now, including mounts

I would think 70 plus is realistic with a well built small block in this size boat?
 
#6 ·
A well built small block could easily push a 17' boat to 70+. The question is what is the hull going to do once it starts getting into those higher speeds? That may be your biggest challenge and I doubt anyone can answer honestly from experience! I can say our 19'6" Baja did 64 MPH with a stock 270 HP 350 Mag. So with say 300 HP you should have enough power to break seventy if you have the driver skill and the boat doesn't get too stupid! :clown: The 5 bolt block should help! :p:

Craig
 
#7 ·
BOSTONCAMARO said:
I take it they are not hard to come by, that is tongue in cheek?

I am new to modifying a boat, so please advise

my dad is going to look at manifolds and some other parts now, including mounts

I would think 70 plus is realistic with a well built small block in this size boat?
Click to expand...

Sorry, man.....Just having a little fun at your expense..
No harm meant...4 bolt mains.....
 
#10 ·
BOSTONCAMARO said:
hehe no problem!

just noticed I typed 5 bolt instead of 4

I am multi tasking here

so what do you think of the cam specs?
Click to expand...
I think that you will have reversion issues with that cam and stock style exhaust (yes, barr is NOT a performance aftermarket exhaust. Neither are GLM's, or anything else that is in their $ range)

I would build and cam your engine to make peak torque @ 4500 and peak HP @ 5500. I built a 383 w/200cc dart heads and the cam picked by a VERY reputable builder (Tyler Crockett) was a crane 100072 (280H, 280 total duration, 228@ 050, 480 lift) I got the impression that anything much bigger will give reversion issues w/stock exhaust.

Keep in mind my motor is also a 388ci. A given cam in a larger ci engine will act "smaller" than the same cam in a smaller motor.

With that said, I would pick a dual pattern cam somewhere in the 280 duration for intake, with more exhaust duration.
 
Discussion starter · #11 ·
jherb388 said:
I think that you will have reversion issues with that cam and stock style exhaust (yes, barr is NOT a performance aftermarket exhaust. Neither are GLM's, or anything else that is in their $ range)

I would build and cam your engine to make peak torque @ 4500 and peak HP @ 5500. I built a 383 w/200cc dart heads and the cam picked by a VERY reputable builder (Tyler Crockett) was a crane 100072 (280H, 280 total duration, 228@ 050, 480 lift) I got the impression that anything much bigger will give reversion issues w/stock exhaust.

Keep in mind my motor is also a 388ci. A given cam in a larger ci engine will act "smaller" than the same cam in a smaller motor.

With that said, I would pick a dual pattern cam somewhere in the 280 duration for intake, with more exhaust duration.
Click to expand...
I think I will go with that smaller cam that I posted about, also will do some port work to the heads...

What are the issues with compression?

besides fuel usage, does higher compression also cause problems with reversion, if so, please explain how and why?

a 9.5 to one motor might be the way to go,,,
 
#12 ·
Your alpha 1 probably has a 184 gear set. I would not go stupid with the engine. I would go with around 270 hp stock merc cam, aluminum intake and aluminum exhaust to lighten the engine up. The diff. between the 3.0 and small block is 300lbs. this will affect the ride and handling of the boat.Also speed becomes a MAJOR concern on a boat that is not set up for running high speeds.Find a complete small block assembly and rebuild. The 3.0 uses a front mount. The small block uses side mounts. I would add some glass structure to the stringers to handle the added weight. If you want I could post some pics of my conversion setup. I cracked the block on my 3.0 and am putting in a 5.0 230hp merc. The boat is a 16.5 bowrider.I posted on your original engine swap. Have fun .
 
Discussion starter · #13 ·
jimslade said:
Your alpha 1 probably has a 184 gear set. I would not go stupid with the engine. I would go with around 270 hp stock merc cam, aluminum intake and aluminum exhaust to lighten the engine up. The diff. between the 3.0 and small block is 300lbs. this will affect the ride and handling of the boat.Also speed becomes a MAJOR concern on a boat that is not set up for running high speeds.Find a complete small block assembly and rebuild. The 3.0 uses a front mount. The small block uses side mounts. I would add some glass structure to the stringers to handle the added weight. If you want I could post some pics of my conversion setup. I cracked the block on my 3.0 and am putting in a 5.0 230hp merc. The boat is a 16.5 bowrider.I posted on your original engine swap. Have fun .
Click to expand...
As of right now, I have about 25 small blocks, as well as tons of parts

I will run an alum Intake, aum heads and alum Water Pump

If I am able I will try to find alum exhaust but have not been able to find any...

I would like to get at least 325hp as that is what I need to have to justify the swap.

As for the stringer I will strengthen it, also plan to extend the mount plates so that to run down the stinger further to spread the load, maybe have them mount in 4 places per side, rather than 2? maybe this is a good idea...
 
#14 · (Edited)
GLM makes an aluminum exhaust for around $700.00 complete search out ebay. Aluminum heads will need a closed cooling system to live long. The open cooling system on a marine setup lends itself to steam pockets in the heads. That why marine manufacturers use closed cooling on hy-po- heads. Two front mounts are plenty, just make sure that you remove the front mount for the 3.0 and glass in a 1 inch min. support that ties the two stringers together.The other problem with running high hp with an older alpha drive is if you don,t rebuild it it will fail shortly. You will also have to raise the x dimension or the stern will become unpredictable at high speed. The pressure on the bottom of the boat becomes exponential at speed. Thats why I suggest you keep the hp within a certain range. Most boats are designed for certain speeds and if you exceed these you could destroy the boats structure. Most speed boats use a core structure for extra stiffness.
 
Discussion starter · #15 ·
jimslade said:
GLM makes an aluminum exhaust for around $700.00 complete search out ebay. Aluminum heads will need a closed cooling system to live long. The open cooling system on a marine setup lends itself to steam pockets in the heads. That why marine manufacturers use closed cooling on hy-po- heads. Two front mounts are plenty, just make sure that you remove the front mount for the 3.0 and glass in a 1 inch min. support that ties the two stringers together.The other problem with running high hp with an older alpha drive is if you don,t rebuild it it will fail shortly. You will also have to raise the x dimension or the stern will become unpredictable at high speed. The pressure on the bottom of the boat becomes exponential at speed. Thats why I suggest you keep the hp within a certain range. Most boats are designed for certain speeds and if you exceed these you could destroy the boats structure. Most speed boats use a core structure for extra stiffness.
Click to expand...
really so alum heads are a bad idea?

wow

i like the idea of tying the stringers together with a brace

what do you suggest, glassing in some square steel? maybe something that bolts to either side, then glass the whole thing in?
 
#16 ·
All I can say is that whatever speed your boat goes now, a 10-15 mph increase will blow your mind.

I have a 22' Donzi that now hits 78 on GPS. It used to go 63 GPS with the stock 454 power. This is a far different boat that what you are talking about.
====
My wife's 17' Bayliner with a wakeboard rack hits around 42 max on GPS with a 3.0 Merc I/O, and I personally wouldn't want to be on that thing going any faster than that.

If I were you, I would buy a better hull, if you want to hit serious speeds. Forget about junk little hulls.
Just my thoughts.
Kent
 
#19 ·
Salt water will ruin your Aluminum heads & Intake in no time...Fresh water you will be fine...Think of a engine in a boat the same as a{big} truck engine..always loaded down & climbing a constant hill...Forget everything you know about drag racing engines {short bursts then shift & light loads}...Things like detonation become very big big problems. Worse because you cant hear the "ping" in a boat.
Agree also about beefing up the stringers & using Aluminum L-angle for mounts...

Fun project !
 
Discussion starter · #20 ·
birdog said:
Salt water will ruin your Aluminum heads & Intake in no time...Fresh water you will be fine...Think of a engine in a boat the same as a{big} truck engine..always loaded down & climbing a constant hill...Forget everything you know about drag racing engines {short bursts then shift & light loads}...Things like detonation become very big big problems. Worse because you cant hear the "ping" in a boat.
Agree also about beefing up the stringers & using Aluminum L-angle for mounts...

Fun project !
Click to expand...
this will be a lake boat only....

alum heads will greatly decrease detonation as it will run ALOT cooler than if it had steel heads

thanks for the advice, keep it coming
 
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BOSTONCAMARO
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