phyreborn

I was considering changing the stock crank with 3.62 stroke for one with a 4.0 stroke. What type of limitations would this create further into my build if any? reduced rpm? what type of power increase would this create? I have also heard that the aluminum ls6 block is good up to about 700hp. Is this true or was someone just throwing out random numbers?

1slowfbody

i'm also considering this, but i'm wondering if the same pistons can be used and if it's only the crank that changes?

sorry for the thread hijack but it's along the same lines

1slowfbody

just got off the phone with SDPC and i'm building a 383 now, thanks for helping me out bud! you'll gain more torque from what i've read and i don't think the stock beams are good for up to 700HP, the forged I beams are only good up to 650crank hp so forged H beam rods will be in my future lol unless a sponsor or a knowledgeable person comes in here and shows me different

mike13

iTrader: (27)

You could go with a Callies compstar crank with compstar H beams, I think that's good to 900 hp.

Tony Mamo @ AFR

iTrader: (13)

Dont expect more horsepower unless your changing the engine's breathing ability (ie better heads, intake, cam, exhaust, etc.)....BUT it will make more average power because the bottom and middle of the curve will be stronger (and more peak TQ....usually around 40 ft/lbs).

Displacement is always welcomed in a heavy street car....the gains in power and torque down low are immediatly evident but some think a bigger engine guarantees more power and that simply isnt true....it only guarantees more TQ and peaks earlier (versus the same set-up in say a 346) unless you have improved its airflow moving abilities as I touched on above. Now if you opt to combine better breathing and more displacement its a powerful 1-2 punch that usually produces the best all around results if set up properly with the right components.

Bottom line its a great move but a better one being armed with a better understanding of what to expect.

You need different pistons and a different crank....may as well buy a complete balanced rotating assy. at that point from Callies, Lunati, Eagle, Scat, etc.

I like the Callies stuff and have used it almost exclusively in all my builds....very high quality for a reasonable price (their Compstar line especially).

-Tony

1slowfbody

its what i'm going with
and this is why i'm goin with a roots style blower on top of my 383 with PRC 243 heads and a good size blower cam. i'm buying the complete balanced rotating assembly from Scoggin Dickey

phyreborn

Thanks for the info. I am starting with a bare block and thought I'd decide on the bottom end first and work my way up. Any drawbacks to the increased stroke? I thought the rods might become an issue and have been considering titanium ones, but I heard that they become brittle. Any thoughts?

jkkaz

Unless you have a really big budget you're better off spending the money on the heads. The bottom end doesn't make you horsepower.

some info on titatium rods: http://www.hotrod.com/techfaq/hrdp_0...nium_rods.html

fatmat80

you are right in building from the bottom up, i went the other route now im starting from scratch.good luck with your build..

1slowfbody

not sure what i was thinking lol more cubes=more power and a stronger bottem end handles HP, i wouldn't chance a stock one with 800HP at the crank

Lambert695

iTrader: (17)

How does the bottom end not make you horsepower?!
More displacement nets more power.. aslong as it can breathe and gets the fuel it requires it will make more power. 346 with AFR heads and a Cam will give you good power.. 383 with AFR heads and a Cam will give you better power.

phyreborn

jkkaz - Thanks for the link. I don't entirely agree that the bottom end doesn't make horsepower. If all I did was swap the crank and pistons and expect a power increase you would be right. But it will increase the power potential, and with the right component selection further down the line I should see increased gains. It's all in how you build it, every component builds on the last. Just like Tony said. And since I am looking at spending 10k+ on this engine I want do make sure that it can handle it. I would be pretty pissed if I just built up the top end and then threw a rod.

1slowfbody - Thanks for the info.

Tony Mamo - Great post. I definitely plan on increasing my airflow. I will end up with a FI setup by the time it is done. Just not sure if I want to go turbo or supercharger yet.

1slowfbody

it's what we're all here for! btw i'm wanting a different route than most F/I guys out there which is why i'm going a big roots style blower on top i priced my build and just the engine alone i'm lookin at close to 12K but it'll be well worth it especially if i hit 650RWHP at 10PSI, even hittin close to 600RWHP at 10PSI is good IMO

BIG_MIKE2005

iTrader: (116)

LOL, man you do not need to spend $12 on a engine to hit 600rwhp.

My buddy & member on here (ChevyChad) made 632rwhp from a basic little forged 347 w/317 heads, Speed Inc boost cam & P1SC Procharger. If someone led you to believe you need to drop $12k on a motor to make 600rwhp with boost, they blew smoke up your ***.

1slowfbody

no i added up the cost of the rotating assembly $2050, the bare block since mine can never be used again $200, the install into the new block $600, all the new bolts and gaskets $300-$400, the 243 heads being shipped to TSP for a stage 2.5 PRC job $1000 (thats with shipping). the blower costs the most out of it $7400. i don't want a procharger because it's common to see on a Fbody i figure if it's my money i'm gonna spend it on what i want not what others think i should do, a roots style blower is hardly ever seen on a Fbody and it's what i want to do. my adding puts that at $11650

BIG_MIKE2005

iTrader: (116)

If your set on a roots type be ready to either use spacers for the k-member or cutting up your cowl. Havent seen one fit yet without either of those mods. I'm all about being unique but I also like to save money if its possible & still get the same end result thats just as reliable.

I would only buy a entire rotating assembly if goin 383. But if you decide to stick with a 346, you can save a decent amount of cash on your short block build. And thats cash you could use toward your FI parts.

But thats just my .02

1slowfbody

yep all that has been taken into, it sucks though i really don't want to cut the cowl but it'll have to be done. the whole engine and trans have to come out so i'll just leave my front suspension on the floor in my garage so i can just slide it under the car when i'm ready to put it back in. the stock rotating assembly is probably garage in the engine, the engine has a hole in the side from a rod going through it lol so a new engine and rotating assembly has to happen, no way around it

btw your advice is useful so thank you! it's what we're all on the site for right

Jwright41

iTrader: (2)

Yea you dont ever see them on an Fbody cause the Cobra guys run them.

1slowfbody

lol they work well don't they? i want that whine when i'm driving! did you know our heads fit and work with some work on old ford small blocks lol rumored our head design was made by a former ford engine developer i think no i went off topic

phyreborn

1slowfbody - Sounds pretty sweet. Best of luck with your build. I always say Do what YOU want and ignore all the negative responses. Because in the end you are the one living with it, not them. As long as it is mechanically sound and safe then there is no reason to change your goals to please someone else. If people knew what I was up to they would have a fit. lol