418 Stroker options....

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d1zzy_duster

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Well I am sure most of this has been answered but usually for different goals so I was hoping for advice for my specific goals, and since you guys are the best here we go:

I have a 68 340 block at the machine shop right now, it is already 30 over atm but has some pitting in 2 cylinders. We are hoping that going 40 over will clean it up, if not then I have 3 options that I would need advice with, either I can sleeve the 2 cylinders and then have a 40 over block or sonic test and go to 60 over, or sell the block and get a different block either a 360 or 400.

the main reason for going 418 stroker is that the block didn't come with anything, just the block the caps, windage tray and the oil pan.

Now I am debating on a blower motor or NA

The car is a 73 duster 340 HI-PO 4 speed Car. I don't know what kind of power the drive train can take but I'm sure I will be upgrading it in the years to come. I want to make a street strip car. I would like to get over the 500HP mark and it would be great to beat my neighbors 700HP blown 350 in his tubbed 32 coupe lol

The one thing I am thinking about is planning for the future, if I do continue with street strip it would be nice to have something I could keep getting more power with like a blower motor and I could just increase ring gap change a pulley and put water meth on it.

as for a budget I am comfortable for 5K-8K for the motor. so please feel free to chime in as I am young (26) and haven't learnt from my mistakes like most of you have done already :)

I am having a hard time finding a stroker kit with low enough compression for a blower. Can I get a 177 blower kit for a 340? where do you guys source this kind of stuff? summitracing.com seems to be kind of lacking in mopar stuff
 
yes...you can sleeve 2 cylinder and have them bored/honed to .040

you can sleeve all 8 if you want to and make it stock bore...or even sleeve down to a 4.00 bore...
 
I know what I can do, but I am more interested in peoples personal experiences like would it be better to sleeve the two to 40 over or just go 60 over? how much is sonic testing? how long will the cylinder walls last before they wear out? if it takes only a couple years then I guess I should go with 40 over ? which option would you go with ? and why?

but the big question is what route to take to get to over the 500HP mark? is the 340 the right block for the task or just jump over to the 400 and do a 498 stroker? I would be happy as can be if I could get close to the 600HP mark, Blower or NA?
 
I just sonic check my 1986 360 block for 75. After boring 40 over the cyl walls were between 170 and 230 thou thick.
 
I currently have my 340 in the machine shop which should be home soon
I had to go .040 on my block as well.
I got my kit from these guys. http://www.campbellenterprises.com/...molnar-technologies-crankshafts.php#sbmcranks

I went with the forged crank and connecting rods from molnar tech
i also got dished pistons from icon in the kit to lower my compression ratio so i could use pump gas (89 octane)

Call campbell and they will set you up. I believe i only paid $2100 for the stroker kit.
The pistons were 360 pistons but +.08

my machine shop thought i paid double the amount for the crank and rods because of the quality and they are very hard to impress.


after the stroker kit i went very extreme and probably did not need to for a street car but i wont have to worry about power
 
With a stroker kit in the 340 to displace 418, making 500 hp just got a bit easier and it is easy to make that kind of power. You'll only need to make 1.19 hp per cube to get 500hp.
At 1.43 hp per cube in a 418 is 600hp. That's still not a lot of power per cube. It approaches what I think, IMO, is a typical well built hot street car.

When you start to exceed the 1.5 hp per cube, your starting to cook. At 1.7 per cube, the 418 is just over 700hp. A whooping .2 jump in power per cube.


Heads are the next key to the combo.

Now the question is are you going to pressurize the engine or not? And do you want a hair drier or through the hood roots style?

Oh, do not be afraid to sleeve the cylinder. So long as the shop can ha doe the job and do it right, you'll be fine. FWIW, a .060 slug is easier to get sometimes than a .040 slug

Switching to a big block is your call. But you can do the math with the new cube size.
500 X's 1.5 = 750hp
500 X's 1.7 = 850hp

The stock trans will not hold.
 
Since you mentioned it; Lots of guys have had success with the 400. It has a really big bore, and a fairly large crankcase and low decks, and a pretty good crank support works.Shouldnt take much turbo to make some serious hp. Cause stomping that 32, is gonna be tough. He has some serious advantages.
 
Here's the thing... You're working to beat a certain car. You say it's a 700hp street rod. What has that car run at the track? (talking hp numbers is irrelevant here) You will not reach a 600hp goal with the budget you have. It would be a challenge to reach 500 with that budget. It's doable - but only just. My point is, you need a realistic goal. Whether that be a blown engine, or a 9 second ride, or an engine for $5K - before you formulate the plans.
 
Premium parts only pump gas 423.5 ci based on a 360. 601 HP, 561 LB-FT torque. Turn key carburetor to oil pan, $9,269 for parts only!
 
In Canada,to achieve your goal of 500 plus HP in a SB stroker you will need double your suggested budget(5-8k).After engine,exhaust,Trans,fuel system and rear you,ll be closer to $20k.You will still be nowhere close to beating the 700hp 32,due to weight differences.Add a turbo and then you,d be closer.JMO
 
Had to sleeve one of the cylinders in my 340 when i built the 416..no problem all the parts and machine shop cost came in just under $9k..520 h.p. 500 lbs tq. putting my '70 duster in the 11.0's..build the smallblock!!!
 
I just put together a 408" stroked 360 Magnum. It has 10.2 to 1 compression and runs on pump gas. It is injected with a modified factory OBDII set-up, gets good mileage and can either be a kitten or a tiger depending on how hard you push the gas pedal. My mild build is likely turning out somewhere near or just south of 500 hp with the mildly ported and Super Prepped Hughes supplied Edelbrocks , Airgap Intake and Big Gulp throttle body on it.

It's extremely quick out of the hole and has a scary fast top-end charge with a 4 speed automatic running a 2.73 first and a .67 overdive, Precision of New Hampton 3000rpm stall converter and 3.91 rearend gears. With a little practice and warm tires, I can almost dead hook on the street with 275/60-15 Nitto Drag radials.

It cost me about half again what your upper budget is for just the motor, and probably the same for the rest of the drivetrain, fuel system etc to allow it to put the power to the ground and still be able to go cross country.
 

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stroked340 said:
Whats it run in the 1/4 mile???..
Click to expand...

Not sure,. I haven't made it out there yet. The closest track is about 2 hours away, and the drivetrain only has a few hundred miles on it. It feels like its in the 11's, but you know how mush that is worth.
 
Thanks for all the help so far guys but just to clarify that $8000 is just for the engine and I was thinking my best bet would be to build a 9:1 compression motor using thinner head gaskets then once I get some more money for it then I will do a thicker gasket and a blower kit. What would a 9:1 418 with mild ported/polished eddies have for power? Then I could push 8lbs of boost into it in a year or two

What kind of cam should I be using for stage 1 knowing my goals and I will re gear the rear end to match planning headers and rpm air gap as well

Thanks again guys
 
Oh and I am not building the car to beat my neighbor I was just poking at the idea lol his is purpose built so maybe one day with a different car but for now my time goal after stage 2 would be under 11 seconds
 
Ok so I did some calculations and I am thinking of stage one I will get a forged stroker kit with -21.5cc diamond pistons and use .027 cometic MLS head gaskets to get 10.2:1 compression with 65CC heads. Then stage 2 will bring a 671 blower kit at 8 lbs of boost using 0.12 or 0.14 cometic MLS head gaskets which is about 8.35:1 static and about 12.5:1 dynamic

so here are the questions: I have never run such a thick gasket and worry about it in a boosted application, what do you think? since the CR will be a bit high, I have 94 octane here and I am hoping that I can find a head with a helpful quench to keep my octane requirements down else I am running water meth....

what heads would you recommend? are eddies a big gain over the knock offs after a blower is introduced? and single or dual plane intake for stage 1?

thank you all!!
 
IMO, your going about this the wrong way. Build for one and not both.
 
I plan on building it for a blower not NA and just running a lower then desired CR while NA but I can't find any better blower friendly stroker kits
 
Did you call the guys in post #5?
 
I would wait until you can build it once and build it correctly. Maybe a better step would be to concentrate on the rear end, strengthening the frame, brake upgrades, fuel system upgrades etc..etc..
 
Just my opinion but if a blower engine is your goal, build it as a blower ending and just run around with really low compression until you can stick a blower on it. I would not want to run a .120" gasket with 4 bolts around each hole, under boost. even mild boost. You will have to have pistons customized because I don't know of any with a deep enough dish off the shelf. But you'd do better to have something that runs 7:1 static then something that runs 10.2 and then gasket up to lower it.
Simply put you cannot have your cake and eat it to. You can give up some power now, or give up reliability later. Choice is yours.
 
Ok thanks I am waiting to hear back from 2 places about a kit that will accommodate a blower. Anyone have any experience with water methanol injection with a blower? How much would it go through? I would want to have to fill it up 10 times to a tank of gas lol
 
Since my goal is to beat the 500HP mark I have decided that it would be best to stay NA and if I want a blower motor I will do a 555 blower for my 72 chevelle and build it from the ground up as a pro street car. So for the duster I need to figure out my max CR I can go with 94 octane and aluminum heads with good quench ect. Also I am curious what I could run as a CR with water meth and either 89 or 94 octane fuel

here is the response I got from Campbell Enterprises:

A 340 stroker kit matching your request would be $2295.00 plus shipping and would include:

Molnar Tech 4340 forged steel 4" stroker crank
Molnar Tech 4340 billet steel H beam rod set with arp2000 hardware
Icon forged piston set 11.5-1 comp with 65cc heads
HP series rod bearings
HP series main bearings
 
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