77scarab300

What does your build on your 355's consist of as fare as internals like rods pistonts intake carb, I see you have vortec heads, but what exact cam do you have, I basically have the same engines as you 355's (.30 over 350's) but nothing special other then .30 over bore and forged steel crank.

TruxtonFox

I have a thread going in General Q&A that goes over what intake, carb, heads and cam will get good power, take a look at that too. But in short, rpm air gap intake, xm270hr cam, Holley 650 dp, and afr 190 heads will "hypothetically" get us over 400 with stock bottom end

77scarab300

Ok awesome I will check out the Q&A thread, and do some pricing of parts, I looked a lot into the LS swap yesterday but probably going to have to stick with my old school Gen 1's for now I think 2 LS plus marine gear is out of my budget for now, I would want to start both engines off fresh rebuilt no matter what I end up going with. Probably build my Gen 1's for 400hp at least and, gather up LS stuff in the mean time, the swap when I have everything needed and sell off my 355's when the swap happens. But definitely headed the LS route.

sprink58

Below is my Dyno run and build specs:

SuperFlow
Dynomometers and Flow Benches
SF-902S

355 MARINE CHEVROLET Result Summary Date 12-20-2012 1:46 PM Temp 80 Deg F. RH 74%

RPM TQ* HP*
2600 399 198
2800 408 218
3000 421 240
3200 430 262
3400 436 282
3600 440 302
3800 444 321
4000 448 341
4200 451 361
4400 450 377
4600 443 388
4800 438 401
5000 431 410
5200 421 416
5400 409 421
5600 396 422
5800 373 411
Max 452 422
Avg 426 339

* Test Exhaust 1.5" Diameter Dyno Tester Supplied Headers.

355-cid VORTEC SPECS

Bore / Stroke / CID: 4.030 / 3.48 / 355 cid
Compression: 9.4:1
Block: GM factory four-bolt 350 L-31 VORTEC
Crank: SCAT forged-steel PN 1101-11133
Pistons: Probe forged (PN 130212334-030)
Rods: Probe (PN 1201-10062) 5.7"
Rings: Total Seal Moly
Bearings: Clevite
Gaskets: Mr. Gasket and GMPP
Cam: COMP Cams (XM264HR) 212/218 at .050, .488/.495 lift, 110 LS
Lifters: COMP (PN 875-16)
Chain: COMP (PN 2100)
Pushrods: COMP (PN 7372-16)
Rockers: COMP 1.5:1 (PN 1417-16)
Heads: GMPP Vortec (Scoggin-Dickey PN SD8060A)
Manifold: Edelbrock Performer RPM Air Gap (PN 7516)
Carb: Demon (PN 1402010VE)
Distributor: Davis Unified Ignition DUI-7000
Spark Plugs: Autolite AR103
Oil System: Milodon HV (pan PN 31505)

I'm running Twin Bravo 1s with 23" Mirage Counter Rotating props. The Formula 255 weighs 5600# dry and with this power jumps on a plane quickly...stays on plane at 2000 RPM....3000 RPM is 55-60. My actual numbers are probably a little less due to using stock exhaust thru prop. This is a very good combination.

77scarab300

Sprink58 thank you for the specs I just wrote them all down, and will see if parts work with what I have, I think you must have newer blocks than mine because my GM number was different and not vortec but it probably doesn't matter, I am running twin Mercruiser TRS out drives, and have the through hull exhaust so hopefully not much flow lost, don't know about my props. But looking at your Dyno sheet I than that sort of power should keep me happy until I can go to some LS engines, and get my Scarab in the water quicker/cheaper, and alow to deal with other issues on the boat also. Anyways thanks for taking your time to post your specs.

sprink58

You're welcome...any time.

77scarab300

Sprink58: I could not get the Scoggin Dickey P/N to work for the GM performance part vortec heads, are running the GMPP (p/n12558060) cast iron 170cc intake runner and 64cc cumbustion chamber heads. I found everything else.

77scarab300

Both my engines have the GM 1182 forged steel crank, any reason why I would need to change this out, the GM 1182 crank checked out fine at machine shop when I had the replacement block for the starboard engine bored 030 over, the engines have just over 300 hrs on them, so not a whole lot of use, but are aftermarket forged steel cranks any better for some reason with a 400hp+ build or can I just save myself some money and use my 1182's that I have.

sprink58

If you trust the integrity of the cranks...use them.