I went closed cooling at 170 F. The idle was quite nice with a big flat tappet. When it was raw water cooled at 140 F the idle was rough.
Steve

Maybe it's just me but i've been building reliable power with smallblocks for years in boats, drag cars, and circle dirt racing. it all depends on your budget. sure a good big block is going to make more power overall over a good small block. but a good smallblock can be just the ticket for some one who does not have the deep pockets of some. the smallblock chevy has been used in most all arenas successfuly for years with no reliability issues. horsepower takes big dollars no mater what you build. jmho

This particular 406 was built in 96- all in , Im about 14K out of pocket today.
Not sure how it would price out today, but Im sure the machining has gone way up parts, likely the same, and the labor has gone up.

Ill leave out a few details- but heres the rough combo.

I used a 2 bolt small block 400 block & splay capped it.
(Ive heard the process referred both as splay capping and side bolting, but thats really a Y-block thing so well stick to splay cap as the term for now)

Its got a Lunati crank and rods in it, and Ross forged pistons coming in at 10:1

Ive got Brodix track 1 heads with a gromm stage 2 port job and 2.10 intake valves in them. Im using a flat tappet Engle cam & lifters , a Brodix Manifold with a spacer and a race demon 850 with the red throat inserts.
Somebody I cant remembers - "Mega" roller rockers that are giant anodized red colored unobtanium something.
Its got a Edelbrock aluminum waterpump on it with a 160 degree t stat.
Single stage stock Merc Seapump.

Idles like a kitten doesn't revert, and roars like a mother.
Runs cheap if you can keep your foot out of it.
Starts every-time! (except for the first one of the year)
It starts making power at 2850 and "signs off" at about 5200
Between these 2 ranges the torque curve is as flat Ive ever seen a SBC, but will pull slowly from there to about 59/6000.

(If I had to buy it all over again Id likely use AFR heads and leave them stock)

Ive got polished Imco powerflow manifolds and added radiused 90's through 4' pipes and tips - no mufflers.

Its also got an aeroquip oil cooler- because I was limited to a 6 quart pan because of mounts etc.

Still using stock mercury ignition to save money. (its been fine)
Still using the stock starter sourced new in 91!

Ive got an assortment of billet pulleys and a tiny bit of bling, only a smattering of braided line and mostly inexpensive but good quality rubber line- its just a good old fashioned well machined small block chevy.

This is pushing about a 2800lb tunnel hull boat.

Anyone else gonna post any combos or just let me do the sharing?

Ive had a bunch of engine combos in this boat, and pulled a blown 383 out when I put this in.
(bot did I learn a lot about blowers with this rig)


UD

Not to hijack this thread but could one of you small block guru's take a few minutes to make me a list of parts that I woould need to make 500hp from a 383sb. Part numbers would be great. Rotating assy, cam specs, heads, as much detail as possible please. Keeping a low budget if possible. Thanks for anyones input.

He actually test drove this boat in 92

Take a look at the pict of his cheeks

This was when it had a the blown 383 in it.

UD

Hey Uncle Dave how fast you get that thing running?
Do you know how much HP your pumping?
400 sbc seem to be a bit more expensive then 350 based engines like the 383. Since 96 and the internet getting big prices have came down alot.
I don't know what you paid then by now a set of spayed caps with all the machining is around 400-500
you can get full forged stroker kits with bearings and all for around $1300 or less a nice set of AFRs for around $1500 new
I would say you can;t really count the extras like exhaust or pulleys cause you would add that to any engine.

When it was fresh it would click 92MPH and spin a 4 blade Hill 26P 6K
It put out like 505HP @ 5300 and 450 lb ft at 4400 on 87 gas.

It completely wore out 3 gimbals!- but never broke a drive.

It's "bled" down to an 84 mph ride after beating on it since 97 -time about 600 hours last calculation for a fresh up.

Maybe parts have gone down, but the machining, port job, balancing the crank assembly etc- and competent experienced assembly of those parts has not- unless you can do it all yourself then cool for you- doenst sound like the poster can really do that.

I COULD have Assembled and have put several pre-machined engines together(the blown 383 & 454 being 2 of them) , but I prefer to pay a guy that does it for a living with ALL the tools.

Good luck finding a competent mechanic to guarantee third party parts can be tricky for both parties.

My 454 was well under this price with 70% used parts with a set of aluminum heads.

I add the pieces like pulleys only to illustrate what Ive done- and to simply provide detail. You guys ask for details - right?


UD

I think the pulleys are an awesome touch.
You say you did the big block well under that but with used parts how much would it have been now with new parts?
Uncle Dave I still haven't got an answer on this so maybe you can answer it.
Wouldn't having your peak torque closer to the rpms you want to run be better then in the lower rpm range?

Hard to tell, but I could likely get the same power output for 10K a side taking the same bargain basement short block with a mild aluminum top end, and a cheapo manifold.

As to your question on torque curves-

It Depends on how you define better?

My Ilmor 710 has a torque curve like you describe and it provides a top end rush like a 2 stroke dirt bike.


This is a 505 CI / 8.3 litre all aluminum fuel injected V10
It has : 700 BHP @ 6,300 RPM & Torque: 650 ft lb @ 4,800 RPM

I can tell you for sure Its better for the drives to move the torque higher up,

- but the boat comes out of the hole more slowly than a comparable 700 HP supercharged V8 which outpulls it till you cross to the midrange and enter the top end.

Not really better just different.


UD

You still need to prop the boat out at peak HP (that is where you want your RPM's). If you prop it out close to peak TQ you will load the engine to much and prematurely wear the engine out. I saw some torn down 496's (stroked 454's) that had 1 1/2 seasons on them. The owner said that he was losing power. After a leak down it was determined there was blow by. When teardown was complete, the bearings showed extensive wear, rings were shot and cylinder wall were just worn. After further investigation the owner stated that he changed props so it would only run 4200 RPM WOT so he could save gas.

I know you are talking about 5200RPM peak TQ, but you would still need to prop it to the ~6300RPM peak HP. That is where I am at with my 468's.