How Would You Build This Stroker?

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MuuMuu101

MuuMuu101

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So, just recently I've been reading up on small blocks and how to modify them as I'm trying to expand my knowledge and experience. For Christmas, I got a couple car related books and lately I've been reading up on "How to Rebuild Your Small Block Mopar" and "How to Build Big-Inch Mopar Small Block." Looking at these, a small block stroker engine may not be a bad, future option in my Dart. Going through these books, I'm learning quite a bit. Now I sort of understand why the 340 is more desirable than a 360.

So, here are the requirements. Car is going to see a mix of street, mountains roads (Glendora Mountain Road is about 5 miles away), autocross, and road racing. I'd say most of its time will be on the streets, maybe once or twice a month in the mountains, once or twice a month autocrossing, and once or twice a year road racing. I'm not going to get into anything super competitive, yet. It's not going to be a dedicated race car. It would need to run on California's 91 octane (as other octanes are practically unobtanium or super pricey). Since this is going to be in a handling car, the lighter the better (an aluminum block seems like overkill, no?). And I care about reliability, a lot. I'd like this engine to last for years to come. Let's just say the budget (carb to pan) is $10k (the cheaper the better, but that seems reasonable, right?). How would you build this stroker?

So, I guess here are my questions...

-How much horsepower/torque would you suggest I need? I'd imagine a fairly flat torque curve would be desirable as I will be constantly slowing down then accelerating.

-What block would you use? 360, 340, R3? So, from my understanding, a 340 is essentially a 360 with a 3.310" stroke and a +0.040" overbore.

-What crankshaft and stroke would you use? 3.580", 3.790" (apparently a couple companies offer it), 4.000"?

-Would you bore out the block? If so, how much? What pistons would you run?

-What heads would you run? Is there a benefit to running W2 heads over (lets just say) Edelbrock Aluminum heads?

-What intake and carburetor would you use? Single or dual plane? Aluminum intake preferable?

-Would you use cast or forged internals? Which parts would you choose to be cast or forged?

I'm curious as to what you guys think or what you would build?
 
I was in your same shoes a few years ago. I built a 416 4" stroke motor. I ran into a very good deal on a 340 block. But would be fine with a 360. If I were you, just go 360 block.

I think $10K is more than necessary. If you've got that money work with Brian at IMM Engines. He isn't too far from you and he's realistic, practical, helpful, and honest.

I'd look at something between around a 450 HP 4" stroker motor. Easy to fart around in, easy to keep in tune, will light up rear tires at will travelling under 30 mph.

360 std bore basic block -$150-200 used
arp main studs -$ 100.50 for windage tray
4" scat cast crank internally balanced (forged pistons, I beam rods, cast crank) -$1,437.97 Summit
hydraulic cam and lifters: around 235 +/-5 duration @.050 under .525" lift ~$ 230-250
comp iron roller rockers, or durable aluminum rockers $560.97 Summit
smith bros pushrods: around $120
edelbrock aluminum heads or equivalent. maybe pocket ported. Don't really need more head for this HP. W-2's take expensive budget robbing rocker gear. $1600 Summit
melling stock volume oil pump $ 46.97 Summit
head studs $128.78 Summit
air gap intake $ 289.97 Summit
750 vacuum secondary carb $ 292.76 Summit
msd distributor $330 Summit
milodon road race pan $427.95 Summit
milodon oil pick up tube $53.97 Summit
tti step headers or dougs $630 plus

With 20.5cc dish ICON forged pistons and a 63cc advertised head (64cc measured) I have 9.7:1 compression. It doesn't ping on California 91 octane. But it is very close. I can't bump the timing at all.

There's items not listed and I missed. But that gives you a rough idea of parts costs. And gives you ideas of where to save money with good used parts. I just looked them up at Summit cause it was handy. Might be able to beat prices.

People advertise motors like that at 500-475 HP range. So you can call it that much if you wish. I like to under promise/hope for and over deliver/get.

This is very close to my motor except I used a 340 block, solid lifter cam, double pumper over 750 carb, single plane intake. That motor would be a tougher to maintain and tune than the one above. But would be very close in power.
 
what autoxcuda said. while you have it apart, maybe pay a little attention to airflow like pocket port and deep gasket match the heads and intake along with 1.6 rockers.
 
EL5DEMON340 said:
what autoxcuda said. while you have it apart, maybe pay a little attention to airflow like pocket port and deep gasket match the heads and intake along with 1.6 rockers.
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I don't think he has the equipment to pocket port or gasket match himself. He'd have to pay to have that done.

Would a CNC'd cleaned up head be good return for horsepower gained per dollar spend??

This would be a nice place for an economical aluminum version of the IMM Engines built RHS-X head.
 
if i´d start over from scratch, i´d try a 4.25" crank from BPE. Gives you about 440 ci with a .020" over 340 block, should make a nice flat torque curve. If you don´t need to rev over 6500 then the piston speed is ok with a good quality piston and this stroke length. A set of ported Aluminium Heads will keep the package light and make some serious power, cam as mentioned above and a dual plane intake will keep it real streetable and torquey.

I agree with getting in contact with IMM engines. He can hook you up for sure.

Michael
 
from a piston and "parts off the shelf" point, I'd stick with the 4" crank. Stock rods wouldn't concern me in the least with this build. Haven't shopped for a build like this in years, but are their KB pistons that would work? They're cheap and not too heavy. Camshaft.... I'd go flat tappet, but that's just me.... gotta pull the valve covers and tinker once in awile just to feel alive!
 
Sorry, this is more of a theoretical build to put a stroker engine into perspective for the future. I don't have a 360 or 340, no tools to build an engine myself, and I don't have $10k in cash to throw down for a stroker build.
 
Just build a solid roller 408 with a set of x or j heads the up front cost of a 360 will be cheaper than a 340. You could realistically build a torque monster for 5k
 
360duster said:
if i´d start over from scratch, i´d try a 4.25" crank from BPE. Gives you about 440 ci with a .020" over 340 block, should make a nice flat torque curve. If you don´t need to rev over 6500 then the piston speed is ok with a good quality piston and this stroke length. A set of ported Aluminium Heads will keep the package light and make some serious power, cam as mentioned above and a dual plane intake will keep it real streetable and torquey.

I agree with getting in contact with IMM engines. He can hook you up for sure.

Michael
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I did the 4.25 with a 4.070 bore (442 ci), 6.2 compstar rods, diamond pistons, indybrock ported heads and custom ground roller cam. It's a 10:1 pump gas motor. probably around 8k invested.
 
What classes do you plan on running ??
What do the rules allow you to do??
Any class that allows the engines your are talking about are probably full out race cars. Or racing vipers and vettes or better. That's why when I was gonna race my Cuda on road course I was gonna try to build a 400 plus hp 273 cause starting with a 340/360 would put me up against vipers and vette.
 
408 or 416, either RHS or Eddy's, lightly prepped / 9.5-010:1 comp./ hyd roller if possible. Maximum reliability/ daily driver,kind of stuff. Brian at IMM is local, knows his Mopars ( not a Chebby guy...) My .02.....
 
273 said:
What classes do you plan on running ??
What do the rules allow you to do??
Any class that allows the engines your are talking about are probably full out race cars. Or racing vipers and vettes or better. That's why when I was gonna race my Cuda on road course I was gonna try to build a 400 plus hp 273 cause starting with a 340/360 would put me up against vipers and vette.
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I was going to do it for fun, not really for competition. The class is called CAM-T. Engine and Trans modifications are unrestricted. The class is for '54-'78 American vehicles that have at least a 108" wheelbase and weigh at least 3000 lbs. No vettes or vipers in this class.
 
Ironmike said:
What? I thought the budget was 10K?

Posted via Topify on Android
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I was just asking people's opinions for a potential future build. I threw out $10k because that seems more than reasonable. I'm thinking 1, 2, 3 years from now.
 
You got a link for that class??

Handling is gonna be a bigger problem than engine power, excessive low end power is gonna hard to hook up coming out of the turns depending on the tires allowed.

You'll want more of an endurance engine than a drag motor. I'd go with the 3.79 stroke will keep better bore and rod ratios plus can be spun to higher rpm. Aluminum heads are more of advantage than aluminum block the higher the weigh the worse it is. Pocket ported eddy probably give you more than enough flow. Fully ported heads are more fragile. I'd start with a siamese block if you can but settle for a 340 or 360 in that order.
bigger bore offers more air flow potentially and Cid.
 
273 said:
You got a link for that class??

Handling is gonna be a bigger problem than engine power, excessive low end power is gonna hard to hook up coming out of the turns depending on the tires allowed.

You'll want more of an endurance engine than a drag motor. I'd go with the 3.79 stroke will keep better bore and rod ratios plus can be spun to higher rpm. Aluminum heads are more of advantage than aluminum block the higher the weigh the worse it is. Pocket ported eddy probably give you more than enough flow. Fully ported heads are more fragile. I'd start with a siamese block if you can but settle for a 340 or 360 in that order.
bigger bore offers more air flow potentially and Cid.
Click to expand...

Here are the rules. Someone posted them on Moparts. Although I haven't seen an official link. Either way, I'm not doing it to be super competitive:

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=8367849&an=0&page=1#Post8367849

As for the stroker, I was definitely thinking of something "mild," yet lighter and very reliable. At first I thought about a 371 ci with a 3.580" crank or something around a 394 ci with the 3.790" crank. The number in my mind was somewhere around 450 hp with a fairly flat torque curve. Not much more so that I'd lose streetability.

As for suspension, I think I'm pretty set up. I'm finishing up an install with the Hotchkis TVS, Doctor Diff big brake kit, and 8 3/4 with an Eaton TrueTrac and 3.55 gears. I'm still waiting on wheels as it's a nightmare. I've got Bilstein shocks I can throw on it, but I'm waiting for Hotchkis to finish up another run of their adjustable shocks as I already placed an order. I'll be running 255/40/18's all the way around on Michelin Super Sports.
 
It seems that what you're looking for can easily be done with a stock stroke 340 or 360.

My build is pretty similar to what it sounds like you're looking for and it can be done under budget (I spent about $7200 since I scrounged used stuff, but about 9k for a completely new one). It made 470.9 hp at 6000 and 455 lb-ft. 400 lb-ft from 3000-6000.
http://www.forabodiesonly.com/mopar/showthread.php?t=241854

The thing just flat out works. Nice and docile on the street, and pretty mean overall.

With a stock stroke, the important things you'll need are:
Quench (0.035 to .040") - basically a zero deck piston/block and closed chamber heads
Heads that flow (edelbrocks work well if they are cleaned up)
Hydraulic Roller cam
Light piston/rod/valvetrain (think Scat I-beams or K1 H-beams and beehive springs)
 
Seems like a pretty good class
hope they run it up here, might be a good one for my Cuda to.
 
273 said:
Seems like a pretty good class
hope they run it up here, might be a good one for my Cuda to.
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Would you still go for the 400+ hp 273 or just give into a larger small block?
 
I would like to, put a lot of thought and research for that engine, love the idea of 5.13 geared 400hp plus 273 roaming the streets. The engine size don't bother me just the bore size, probably give up 30 or more hp across the board. I just see engine size as a power band selector anyways.

If I was to build an engine from ground up it would be a 340, if from a low mileage short block it would be 5.9.
 
273 said:
I would like to, put a lot of thought and research for that engine, love the idea of 5.13 geared 400hp plus 273 roaming the streets. The engine size don't bother me just the bore size, probably give up 30 or more hp across the board. I just see engine size as a power band selector anyways.

If I was to build an engine from ground up it would be a 340, if from a low mileage short block it would be 5.9.
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I just quickly read through your engine thread yesterday. It's interesting as I've got a tired 273 in my Dart and a spare block. I'd like to do a mild build and assemble it myself sometime in the future as a fun mini-project. I haven't figured out what I'd put it in though.
 
Having built a few of these, I would tend to go for the longer stroke, not necessarily a 4.25( that really depends on whether highest average torque is your priority over peak HP) but something over 4". The reason being you have that tall 9.58" deck height that ( to me ) you might as well try to fill since a tall Compression height piston just adds weight.

When I rebuild my 414 someday I'll probably look at doing an offset ground 2" rod journal and add some stroke to maybe 4.1". Why not? It's an extra 11 cubes and a lighter bobweight. I'd use at least a 6.125 or maybe even a 6.25 Rod. 11 cubes is not much but that's another 6-8 degrees of intake duration I can run with no downside as well so at 1.35 ish lb/ft and 1.3 hp per cube it's close to another ~20 to the good
 
No-brainer: block would be a 1993-2003 5.9 Magnum 360. Cheap, easy to find, better heads, already designed for a roller cam, and not 30+ years old.
 
If think if it were me and knowing you have some road racing in the future - I'd stay with a 360: 3.58 stroke. You can make the same horsepower as a stroker, but it will be spread out over the rpms more, and it will live a bit longer, and rev higher on the same given top end. I think you'll be out of rpm with a mild rear gear and 4sp with a mild stroker. And a not-mild stroker will blow the budget. Road racing is not about horsepower. It's about enough power, and not having to slow down. A really good chassis can outrun a a really strong engine. So that's how I'd go.
 
moper said:
And a not-mild stroker will blow the budget. Road racing is not about horsepower. It's about enough power, and not having to slow down. A really good chassis can outrun a a really strong engine. So that's how I'd go.
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I totally agree with you, there was a guy up here running open wheel with a two barrel scrap yard 360 with a bit of a cam as the only mod. He had it setup so well he could run deeper into the corners before braking (brakes are as important as power also) he'd always pass two cars every turn, he barely had enough power to maintain his spot until the next corner. Plus with too much bottom end it can make it way to hard to hook up out of the turns.
Plus large engines drop off sharper after peak power than smaller giving you less of a power band to play with.
 
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