High revving 340 build

[71roadrunnersassy]

Ok so I have decided I want to go for a high revving 340 roadrace engine setup in the roadrunner. want to get am r3 48* Siamese bore race block get stock steel crank and run w9 heads. Want to build it to have around 600hp and run up in the 7500 rpm and above range. Was looking at the mildon roadrace baffled sump and an oil accumulater to control librication as I know that's very important.
I also would love to run a six pack setup but can't do that with an r3 can I?
Car will have a 4 speed trans and maybe 3.10 gears or something like that.

All thoughts and advice is welcome as this is my first build and have much to learn and this place has great people with great info and experience. Thanks.

 

[Meep-Meep]

While I can't comment about the specific parts, past data shows that elevated RPM's will require attention to specific components if you want it to live. The crank needs to be strong enough to keep it from going into the first critical (terminology related to balancing). The valve train needs to be brutally strong and your cam profile choice can either be a blessing or a curse. A high strength billet cam might be a good choice to avoid acting like a torsional spring. I believe most of the aftermarket parts today are no brainers for this kind of duty, but doing this with a stock crank might be asking for trouble. Look at K1 Technologies. I believe they have the best "off shore" stuff out there. WISECO pistons are good too.

 

[Herr_Poopschitz]

Ok so I have decided I want to go for a high revving 340 roadrace engine setup in the roadrunner. want to get am r3 48* Siamese bore race block get stock steel crank and run w9 heads. Want to build it to have around 600hp and run up in the 7500 rpm and above range. Was looking at the mildon roadrace baffled sump and an oil accumulater to control librication as I know that's very important.
I also would love to run a six pack setup but can't do that with an r3 can I?
Car will have a 4 speed trans and maybe 3.10 gears or something like that.

All thoughts and advice is welcome as this is my first build and have much to learn and this place has great people with great info and experience. Thanks.

Seems like a big mish-mash of parts/desires. Those are pretty exotic parts that require expensive supporting parts for 600 hp.

What will the car be used for?

 

[71roadrunnersassy]

Seems like a big mish-mash of parts/desires. Those are pretty exotic parts that require expensive supporting parts for 600 hp.

What will the car be used for?

car will be used for road rally events and some circuit racing also and i want it to be high and fast revving.

 

[charger318]

its not THAT hard to run 7,500 rpm on a small block 340. my dads 383 with 440 crank and 452 ported heads runs to 7,000 rpm and the 440 crank has more stroke (3.75 I believe) then your 340 (3.31 stroke). NOW that being said you need to know that at 7,000 rpm plus rpm's any engine now matter how much balancing or money u throw at it can blow. you will want to lightest rotating assy you can get, I think stock you have a cast crank, I would recommend forged for those rpms, you will want to stud everything mains rods and heads, use arp studs. and like meep said pay attention to cam and valve spring specs. and you'll want windage tray if you don't have one yet, high flow oil pump, and deep oil pan 6-8 qt so you don't empty pan before oil and get back to it.

 

[Meep-Meep]

its not THAT hard to run 7,500 rpm on a small block 340. my dads 383 with 440 crank and 452 ported heads runs to 7,000 rpm and the 440 crank has more stroke (3.75 I believe) then your 340 (3.31 stroke). NOW that being said you need to know that at 7,000 rpm plus rpm's any engine now matter how much balancing or money u throw at it can blow. you will want to lightest rotating assy you can get, I think stock you have a cast crank, I would recommend forged for those rpms, you will want to stud everything mains rods and heads, use arp studs. and like meep said pay attention to cam and valve spring specs. and you'll want windage tray if you don't have one yet, high flow oil pump, and deep oil pan 6-8 qt so you don't empty pan before oil and get back to it.

Sure - I used to shift stock bottom end hot cammed 340's at 7000 - 7200 RPM no problem. All I'm stressing here (no pun intended) is he might spend more than a shift point worth of time at 7500 RPM, plus he might go over due to a missed shift or ?? so I think err to the side of overkill is in order. I will also add that he should not externally balance the engine. Not that there is any reason to, but just throwing it out there. Agreed on oil mods, etc....

And some FYI. A lightened flywheel will make it rev quicker but don't take away so much material that it becomes weak. And I wouldn't even think of running the factory cast flywheel. Billet steel SFI all the way. Also check with the manufacturer to see if they will supply a lightened version or have some approved spec for removing material. Lots to think about when living in the upper RPM range.

 

[Herr_Poopschitz]

car will be used for road rally events and some circuit racing also and i want it to be high and fast revving.

Are there restrictions/rules/limitations? So this will not be a street car? Budget?

 

[PoppaSmurf]

Sassy there's a lot to consider here, suggestion contact Cambell industries K1

( http://www.campbellenterprises.com/...ogies-connecting-rods-crankshafts.htm#catalog)

for a forged crank and H-beam rods, or even check with Carrillo, or Crower make sure BOTH are 4340 forged steel, look at Ross pistons, a good roller cam and valve train assembly, make sure you have Everything in the rotating mass balanced to within 1/2 gram.. INCLUDING a forged flywheel, you can even go so far as milling pin bosses, rod ends and tops ( were talking a couple of grams per piston rod assembly, your going for the lightest bob weight possible before balancing) knife edging the crank shaft if legal... to give you some good direction, contact my friends at Arrington Performance Engines, they build some of the strongest NHRA, NASCAR and SCCA Mopar engines around... talk to Joey Arrington and he'll guide you through your build...and help you achieve your goal
tel # 704 795 1087

 

[71roadrunnersassy]

Are there restrictions/rules/limitations? So this will not be a street car? Budget?

No restrictions or rules or anything and I'm just planning at the moment and trying to get ideas so I make sure I make a good choice that I won't regret.
Car will be driven on the street but only to and from track days and what not so streetability isn't really too much of a problem.

Looked at k1 and they only sell stroker cranks but did find an eagle with stock stroke made of 4340 steel and is supposed to be stronger than stock.
There are also differing opinions on forged or billet con rods and which is better.
From how it seems the billet seemed a better option?

 

[PoppaSmurf]

In my opinion forged would be the better way to go I'm including an article (see link) that might better explain the differences remember this applies to the crankshaft as well.. either way.. balancing plays a VERY LARGE part in sustaining high RPM for extended periods of time.. and helps with the longevity...also consider things like bearing clearances .. but a good engine builder will talk you through this..
Here's the link
http://www.enginelabs.com/engine-tech/connecting-rod-tech-forged-and-billet-steel-rods/
Keep us posted

included below a link with some input on bearings and clearances

http://www.enginelabs.com/engine-tech/the-simplicity-and-sophistication-of-engine-bearings-part-1/

 

[Coronet 500]

My dream to build one of these.

http://www.moparmusclemagazine.com/techarticles/engine/mopp_0310_340_engine_600_hp/viewall.html

 

[71roadrunnersassy]

In my opinion forged would be the better way to go I'm including an article (see link) that might better explain the differences remember this applies to the crankshaft as well.. either way.. balancing plays a VERY LARGE part in sustaining high RPM for extended periods of time.. and helps with the longevity...also consider things like bearing clearances .. but a good engine builder will talk you through this..
Here's the link
http://www.enginelabs.com/engine-tech/connecting-rod-tech-forged-and-billet-steel-rods/
Keep us posted

included below a link with some input on bearings and clearances

http://www.enginelabs.com/engine-tech/the-simplicity-and-sophistication-of-engine-bearings-part-1/

Thanks for the link was very informative and forged does seem the way to go.
Was reading about the eagle crank and there is very mixed opinions about them. Is there any other places that sell a stock stroke crankshaft? Have looked but have no luck.
What about pistons? Is it a good idea to stay with a smaller piston to keep the weight down or is it not so much of a problem? Plus where is a good place to get them?

 

[AMX364]

It sounds like you want to build a NASCAR type engine from long ago. It would run like a Nascar engine, but not good for the street. Are you sure you want to do this?
At one time, not that long ago, I wanted to build a "stock" type Chevy 302 engine. A 383 Chevy would have been a better idea.

Cost wise a 426 single 4 barrel would be about the same cost.

 

[Cranky]

As for street driving a race engine, there's lots of things to consider. Generally race parts do not like low rpm use. Racing engines like big cams to produce the power you are talking about in the rpm range you want to run. Even tho they will last for a certain period of time, street driving seems to take it's toll on valve springs. Imo, it has to do with heat. Any spring will produce heat all by itself when it's worked no matter what the condition and the bigger/heavier the spring is, the more heat it will create then add the heat of the head to the equation. Oil supply to the spring is critical because over heated springs die quickly and oiling can because an issue when driving on the street at low rpm for all systems.

You mentioned a 3.10 gear? What's that going to do on the street for your competition clutch setup? A light weight flywheel will allow you to rev quicker but you will have to get on the gas and slip the clutch more to get the car moving from a stand still. The inertia from a heavy flywheel helps to keep the engine from dying when you apply the clutch without much clutch slipping. How much stop and go do you have between your home and the races that you will be attending? High strung stick cars do not like street driving very much. And how bout your cooling system? Will it do the job at low speeds? Just a couple of thoughts I had....

 

[kb67mopar]

I had a friend who raced amateur stock cars. He routinely revved it to 8k rpm (was a chevy based motor though). The one take away from that thing was that it had NO torque below 3k rpm. He had to rev it over 3k just to move the car and clutch it. If you don't need the extreme high rev capability I would seriously consider sticking to 6500 as a top end and build something a bit more low end friendly...will save you some $$ too.

 

[rumblefish360]

This is where stroker small blocks come into play. Moving from a 3.31 stroke to a 4 inch or 4.25 stroke adds mocho cubes and torque quickly. The added displacement eats up some duration. Still, installing a big cam kills drivability. Along with the assoc. gear used in such apps. High stall and 4.30 plus gear ratios.

But a stroker is a little more livable on the street with the same cam.

On FABO, there is (IIRC) DJVcuda that has built a 4.25 stroke 360 to a 435 cube engine. Contact him on that. He has a good thread on it.

 

[71roadrunnersassy]

Yeah I'm pretty set on this idea and building a stroker is just not something I am interested in doing for this car. I won't be driving it on the street very often at all as this will be a race car. It helps that I live right next to a freeway so not much traffic I have to fight through to get onto open road. I know this kind of an engine will require high dollars and maintanence but I am prepared for that as this is something I've always wanted to build. A good option would be for me to speak to an engine builder that knows mopars which could be hard to find as it's all Chevy and ford everywhere. But thanks for all the help and advise.

 

[Coronet 500]

Good reading here.

http://www.jegs.com/InstallationInstructions/300/312/312-P4876381AB.pdf

 

[rumblefish360]

Well if such is the case! Slam dunk yourself a nice solid roller and have at it!
Good luck and enjoy!

 

[Herr_Poopschitz]

W/ W9's there's no reason you can't build a 400+ stroker and still turn 8k RPM. If there're no rules, the rotating assemblies shouldn't cost much difference, and you can make MUCH more power. 600 hp is for stockish heads, not W9s. Go to yellowbullet and look at some of the builds over there for induction system potential.