how much horsepower?

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mopar_stroker

mopar_stroker

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How much horsepower can a smallblock mopar handle? when do the block collapse, crack? rods? pistons? are the 318 and 340 the same block?
I have no experience of the smallblock. Now I´m running a BB505 in my dart -68, but it would be fun to build a turbo smallblock..
 
If you are going the route of turbo, you should not be looking at any factory parts. Start witha good block, and build from there.
 
The biggest problem with forced inducted or highcompression LA's is the head bolt arrangement. It's tough keeping a head in place with only 10 head bolts.


Chuck
 
My 360 magnum block stroked to 406 with 16 lbs boost has been running for about 2 years now without any problems at all. Through a 727 it dyboed 580 to the wheels
 
My friend joe's factory block boosted 418....

And that's at the tires through a t-56 BTW...

IMG_0237.jpg


Only problems he seems to have are oil control related as in it finds it's way through everything lol.
 
I have a little high boost experience with GM stovebolts... Ring seal is a big issue on it because the bores move all over... As you can't get a better block (meaning thicker walls) it was sleeved, the deck completely modified, and the block filled (runs on mechanically injected methanol). Oil coming out everywhere is a sure sign of pressure leaking by the rings and the block "moving around" under the load. Turbos won't kill the mains although I'd assume he did something down there.
 
moper said:
I have a little high boost experience with GM stovebolts... Ring seal is a big issue on it because the bores move all over... As you can't get a better block (meaning thicker walls) it was sleeved, the deck completely modified, and the block filled (runs on mechanically injected methanol). Oil coming out everywhere is a sure sign of pressure leaking by the rings and the block "moving around" under the load. Turbos won't kill the mains although I'd assume he did something down there.
Click to expand...

RyanJ Built it. It's bottom filled and uses an oil cooler.
Very weird looking pistons in it too. They're a dish with a weird looking nipple thing in the middle and some gold colored thermal barrier coating.
It's safe to say there's probably some movement going on in there. no doubt.

Strange stuff. After bothering him for a while he bought an r block, but I dont know when he'll use it. I will say that it's a very, very nicely dont engine with all top notch stuff.

It's paxton supercharged.
 
Mad Dart said:
That thing must move some pavement once it hooks!

What compression ratio is the engine built at?
What kind of fuel is he burning also.

I ask because I am getting an itch to build a TT set up soon!
Click to expand...

He does have traction problems.

Well stay tuned. He's building one too with his r3 block, and he's selling the paxton. Runs on pump premium and the static compression I think is like 8-8.5:1 right now.

These things can take a lot, but you have to be mindful of how you approach it. If you just slap a paxton on a factory engine, you're gonna kill it in short order. Most people do when they dont know where "enough" is.

Where is the SDCE guy on here? He sells the TT setup for the magnum engine. He would be the guy to talk to as a starting point.
 
340mopar said:
The biggest problem with forced inducted or highcompression LA's is the head bolt arrangement. It's tough keeping a head in place with only 10 head bolts.


Chuck
Click to expand...

and at the same time, look at the sb mopar in early 70's [lil use but still]nascar, ford is the same boat, but there isn't constant issue with only having 4 bolts around the cylinder, but still can come into play at some point maybe.

I believe the biggest obstacle is the smaller main caps that will crack or are prone to at that level, they found this out in the 80's with mopar performance 318 race blocks that would 340 bore, but still had regular 318 main caps.

the way the mains are loaded, it would probably be the no.1 main that gives 1st.

I've heard 500-550 is the limit anf depends on the compression [cyl wall splitting] and parts weight etc..
I think the better question would be 'how long will it last beyond 600 hp'
jmo
 
POS Dakota said:
He does have traction problems.

Well stay tuned. He's building one too with his r3 block, and he's selling the paxton. Runs on pump premium and the static compression I think is like 8-8.5:1 right now.

These things can take a lot, but you have to be mindful of how you approach it. If you just slap a paxton on a factory engine, you're gonna kill it in short order. Most people do when they dont know where "enough" is.

Where is the SDCE guy on here? He sells the TT setup for the magnum engine. He would be the guy to talk to as a starting point.
Click to expand...

I would probably do it with a 360ci motor. Run about 12-15 lbs of boost with the ability to dial it up to 20-25lbs of boost max. I have all the parts to do one accept the pistons and the turbo set up. Maybe do a single turbo?? IDK, trying to learn as much as I can. I may change my plans on the 67 Dart.

What about all these guys running BOOST with stock internals and they live? Do you absolutely need a HUGE $$$ Engine to make it work correctly with boost? I am beginning to think that is a MYTH!!

The DynoJet is a Chassis Dyno right?? Those numbers are to the pavement?

Damn that is knarly for a little truck!
 
Mad Dart said:
I would probably do it with a 360ci motor. Run about 12-15 lbs of boost with the ability to dial it up to 20-25lbs of boost max. I have all the parts to do one accept the pistons and the turbo set up. Maybe do a single turbo?? IDK, trying to learn as much as I can. I may change my plans on the 67 Dart.

What about all these guys running BOOST with stock internals and they live? Do you absolutely need a HUGE $$$ Engine to make it work correctly with boost? I am beginning to think that is a MYTH!!

The DynoJet is a Chassis Dyno right?? Those numbers are to the pavement?
Damn that is knarly for a little truck!
Click to expand...

To the pavement. That's over 800 flywheel.

I would go with an h beam, a forged crank and a good dish piston. Yeah some live, but not at this level. No way...you usually can get about 450 rear wheel with a paxton and a good tune before **** happens with the factory guts. I know "this guy" who blew his stock motor at that level once upon a time...tee hee.:-D

Anyway....

These are his pistons...and I think you can figure out what gasket goes on there.
IMG_6210.jpg



And yep, that's a MAG block!!!
It's filled, but I doubt a block fill does a whole hell of a lot. It does something I know, but how much, who really knows?

But in a motor like this, the pistons are very important.
Weird arent they? Those are custom diamonds I believe with a special barrier coating on them.

Factory pistons WILL NOT live at this level.
They will die well before that.

Anyway, not to get too far off topic, let this be testimony to what the block can live through. Will it work for everyone with every day mom/pop machining and budget parts? NO. But done right, there it is.:cheers:

So in the context of your n/a stroked smallblock, you have nothing to fear about the block as long as you dont get too stupid.
 
P.S. with 20-25 psi you'd need a heavy duty r block based setup. You'd need the extra head bolts FOR SURE and I would recommend EFI and the enlistment of a good tuner. a factory block wouldnt live through that.

20-25 psi would be 4 digit HP. LOL I would be scared!

12-15psi and you would smack the living crap out of anything on the street. lol
The r block can do about 1500 hp.
I wouldnt even try more than 18psi and that's bold IMO.
I dont say that because it cant be done. I say that because my skills arent at that level to drive that, or to tune it.
 
Great information POS, Thanks a bunch!

With a stock stroke 360 at 0 deck with good quench at .039 you would need a Dish Piston of 29cc with 62 cc heads to get it 8.5:1

On a 408 with the same heads you would need 40cc dished pistons with same 0 deck and good quench at .039!

YES those are some Crazy looking pistons for sure!! First time I have ever seen pistons REALLY DEEP like that.

Yeah, I don't know WTF I am thinking............Crazy sitttttttttttttttttttttttttttt...........haaaaaaaaaaa
 
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