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Small Block Engine Specs

Robby Bondurant

Well-known member
Does anybody know how much HP and torque a 98 Vortec 350 bored .030" over would generate? Or just a bone stock 98 350? I have tried to research it and can't come up with anything.

As far as I know the cam and crank are stock. It has brand new hydraulic roller lifters, bearings, gaskets and seals, has brand new edelbrock intake and carb. Brand new HEI distributer, starter, alternater, and water pump.

I was just curious about the specs because I just wanted to know what I was dealing with. Thanks in advance, Robby.
 
Robby
With a valve lift of .480 and that’s about stock, and a total duration around 270.
You should be looking at around 290 HP @ 5000 rpm and 365 foot pounds of Torque @ 4000 rpm.
 
What size carb and what kind of intake is it a performer or performer RPM. Also remember the longer the primary tube is on your header the lower RPM your peak torque will be. I would run a 1.6 ratio rocker with a super sucker plate with a very long primary tube you could see up to 310HP if it's a .480 lift but I doubt it is. Besides the cam you have a good package but the stock cam will limit you it's probably on a 112 or 114 lob separation the stock 290 HP has a .450/.460 lift and the 260HP has a .383/.401
 
I put the performer vortec intake on it along with a 600 performer carb. I have no clue what size the tubes are or anything like that. How could I find out that info? Thanks for the replies, Robby.
 
Hey Robby;
are you running direct drive? If so, your max rpm will be around 3000 I would think. So your HP and torque numbers won't quite that generous.
If you're running a reduction you have those larger numbers. This is all predicated on your prop choice of course...Jim J
 
I know the dd cant turn much more than 3000 rpm, but i cant afford a gear box. I was just wondering about how much this engine really had that's all.
 
Yup, we all know how it is with money constraints. When the time comes though, buy some sort of adjustable pitch prop even if you have to get a loan, this will help you dial that motor in just right....Jim J
 
The Vortec is a good starting point.

Second the points by Thunder (cam) and Dragonfly (adjustable prop)

I'd call Comp Cams and Crane and tell them you have an airboat and can they help you with a cam. They might recommend a cam that sounds big to you, but cam tech has come a long way. You need the engine to breath and to kee the dynamic compression ratio (how much compression the engine actually sees) to be optimized.

You do need to know about what your static compression ratio is

I would recommend a 4 blade Warp Drive or a 2 blade Sensenich Q Series prop. I think it is almost impossible to pick the perfect wood prop because there are way too many variables from engine mods to hull weight etc etc..... The adjustable pitch makes it a lot easier to get your boat dialed in.
 
Robby, I agree with Dwarf about the prop ..... it might seem a lot of money at first, but if you buy a fixed pitch paddle prop and then find out it's not what you really need, the adjustable pitch prop is going to look like a much better deal.

Keep your eyes open for a low-time adjustable 2 blade that somebody is wanting to sell ........ you can often pick up one for less than a $1000, and a new wood prop will cost you almost as much.
 
I'm working on getting a 5 blade warp drive with 65" blades. The guy ran it on his dd 350 on a 12' boat, Said he could run dry with his wife and his two little kids turning at about 2700 rpm. I just dont know if it will bolt up to my newer model crank? Thanks everyone.
 
The good news is that most props have the same bolt pattern, known as "LXL"

All you need is a prop adapter from the new style 1 piece rear main seal Chevy to the standard pattern. They are usually 2" thick, but make sure you build your rigging so that you will have a lot of clearance for the prop; Warp Drive blades like to flex. I ended up having to stack a pair of 2" spacers for clearance because I didn't think of that when I built the stand.

Most of the major airboat mfg's should carry this adapter, but I have found often times they will be out of stock.

I think GTO and Classic usually keep them, so you might try one of them.
 
I think it should come with the adapter because he's wanting to get a powershift. I'm down in the keys right now, tryin to find some lobster, but i will find out more about it when i get home. Thanks.
 
I wouldn't say "drastically", but I think the idea is that your prop will be farther from obstructions like the radiator and rigging, so it gets a better "bite" of air.
 
I have done it and it changed prop RPM's more then a lot of other things people do. The other major problem is where most car motor boats locate their radiators that makes a noticeable difference also. I have ran a DD with a prop pulled it off then changed to a longer adaptor and noticed the difference.
 
Where's the best place to put the radiator? In front or in back of the motor? How many inches away from the engine are you talking for the adapter?
 
objects in front of the prop causes turbulence but for cooling I have to have the radiator down in front of the prop. Does anyone have a formula.
I use to have the radiator in front of the motor but it would not keep this motor cool like the old 350 did
 
i have the specs on the cam for your 1997 threw 2002 vortec engine int. .414 exh. .429 duration192/197 on a 111 degree lobe seperation and if you use 1.6 rockers you will need the guides cut down the retainer will hit the guide seel i use ls6 valve springs and retainers the behive style to get .550 lift and do no machine work but that 290 hp to about 310 ho is about all you will get with out a cam swap i use the lt4 hot cam advanced 6 degrees on 1.65 rockers and there is power threw out the rpm range idle to 6200 but to use this cam with those heads and thease rockers you must do the valve guide machine work but it will get you a honest 25hp if not 40hp depending on the headers and carb and intake combo that you use
 
Hi, I can't tell you squat about props, nor vortes combos other than you can get 300 cfm out of the heads. That's the last thing you need DD. What you want is the most stopped up intake available and a lower lift style of cam if you intend on 3000 rpm or less. The smaller the port, the faster the air at lower rpm's. A properly done low lift with shorter duration cam will "jerk" the air into the cylinders efficiently and will aid you until you reach the efficiency of the cam/port ect... Basically what it does is get the air movving quickly when it really shouldn't be, the smaller ports and intake runner aid carb signal and make this easier to happen. That's why a stock junky ass iron intake on a Cadillac DD unit does better than a performer alum. intake, because the ports are smaller.
 
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