road race engine...

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Mopar87

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You can get 400 hp out of a 318 just by fixing the compression ratio, and allowing more flow in/out of the engine.According to this article 318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine it can be done on the cheap. My question is what would it take to make that engine live a long life at a sustained 6000 rpm?By sustained I'm talking hours at high rpm and high loads.Goal is 6K rpm sustained, with a 6800ish redline for when your either lugging the engine in one gear or spinning its nuts off in a lower gear.

I was thinking of building a 5.2 magnum following the same receipt with a few other tweaks thrown in for good measure such as deburring the block,porting the oil pathways,balancing the engine,better valvetrain,etc, then topping it off with fuel injection with distributor-less ignition

How many stock parts could be reworked and reused (ie polished/shotpeened connecting rods)?I can do most of the work myself,and I understand that some new parts are essential.At the same time however, I would rather not pay for Summit Racing's employee christmas bonus out of pocket.

Engine would go in my 73 scamp with a 5 speed manual transmission 3.91 or 4.10 gears, 29" tires...
 
Live a 6K for hours?

I’d use the Milodon road race pan and open up all the oiling passages starting at the oil pump. Your 6800 rpm is not suited to stock oiling passages. You should consider 6500 as a max though some blocks will oil better than others. Don’t gamble! Treat it like there is an issue at 5500 rpm and address it from there and make it right.

I wouldn’t reuse the stock rods unless they were perfect coming out of the block. New lighter and stronger rods are cheaper than fixing OE rods.

While I get the quip of the Summit racing employees bonus, that is actually your very last concern that should not even come up on your death bed many years from now. Do it right, do it once or pay twice in doing it over again.
 
29" tires?

Like Rob said invest in quality parts and machine work. Skimping a few hundred bucks could cost you thousands.
 
I’d get all new high quality forged bottom end, from whoever that might be.?.. the guys on here will know. I think some companies also knife edge the crank, how effective it actually is, I don’t know. Never had one.. Solid cam, nothing hydraulic. Do all the oiling mods necessary, maybe get a blueprinted high volume oil pump from Precision Oil Pumps...

Look up B3RacingEngines, at sustained high RPM your rocker arms/valvetrain must be perfect. His kits will get you there.

Might want a 26” radiator, properly shrouded...

It might be wise to list the gear ratios in the transmission you are using...

I don’t know. I’d maybe even look for an R3 block. I always wanted to build an R3 engine.
 
Skip the R3, use a Magnum block.
Comp Cams has rockers that can oil through the pushrods for use of LA heads on Magnum blocks.
 
You can get 400 hp out of a 318 just by fixing the compression ratio, and allowing more flow in/out of the engine.According to this article 318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine it can be done on the cheap. My question is what would it take to make that engine live a long life at a sustained 6000 rpm?By sustained I'm talking hours at high rpm and high loads.Goal is 6K rpm sustained, with a 6800ish redline for when your either lugging the engine in one gear or spinning its nuts off in a lower gear.

I was thinking of building a 5.2 magnum following the same receipt with a few other tweaks thrown in for good measure such as deburring the block,porting the oil pathways,balancing the engine,better valvetrain,etc, then topping it off with fuel injection with distributor-less ignition

How many stock parts could be reworked and reused (ie polished/shotpeened connecting rods)?I can do most of the work myself,and I understand that some new parts are essential.At the same time however, I would rather not pay for Summit Racing's employee christmas bonus out of pocket.

Engine would go in my 73 scamp with a 5 speed manual transmission 3.91 or 4.10 gears, 29" tires...

No need to spin that high. Plus, you will have to spend big money to make it reliable at those rpm's. Why not build a nice stroker 5.9 with ported Eddie's and the right roller cam? I love mine on a road course, the drag strip or for hot street fun.

I'm running 28" rears with 3.91's and a .67 overdrive 200R4 with a 3800 stall 3 disc lock-up converter. The thing will go well north of 150mph, which is way too fast.....most of the time.
 
Their donor engine already put 200HP to the rear wheels?

...from a gross rating of 230 at the crank and with factory exhaust manifolds?????
 
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...and there's another reference to the max valve lift of Magnum heads before machining is required, that no one seems to know about around here.
 
...but all in all this seems to bode well for my future (advertised at 9.2:1) LA roller/Mag head build using the Lunati roller cam that ends up at .517 lift at 1.6
 
I'd start with the oiling mod stickie at the top of the forum
I'd start with a dry sump system, big oil cooler, piston squirters, oil to the valve springs and insulated spring seats, etc
gear drive
look at sprint car and NASCAR truck builds, what rollers NASCAR using now?
needle bearing rockers or rollers???
ask Krooser
 
I'd start with the oiling mod stickie at the top of the forum
I'd start with a dry sump system, big oil cooler, piston squirters, oil to the valve springs and insulated spring seats, etc
gear drive
look at sprint car and NASCAR truck builds, what rollers NASCAR using now?
needle bearing rockers or rollers???
ask Krooser
Yep... oil flow and oil cooling are going to be critical to keep things running at these RPM's long term, above and beyond parts fatigue. I'd not approach this without forged bottom end parts, forged pistons, keeping the rotation weight down, etc. I'd also be moving to AL heads immediately, somply for the lower weight; weight loss (or moving it where you need it) in this application outstrips adding HP. So Summit employees et al are going to get their bonuses!

OP, is this for a Lemons race or what? Any particular courses? Interesting project.
 
Think more rally car and less pavement.Without going into details or specifics lets just say I like to drive fast down rough roads many miles from BFN.
 
Built on "the cheap"??? No chance unless you own the machine shop. That engine was cleaned, bored, decked, 8 rods resized, balanced, And built with brand new head castings. And the output is actually not impressive at all when you figure power per dollar. A bone stock junkyard 5.9 magnum can make near that with a cam and intake swap. Now THATS a budget build!
 
You can get 400 hp out of a 318 just by fixing the compression ratio, and allowing more flow in/out of the engine.According to this article 318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine it can be done on the cheap.

That article gets referenced often but I have yet to see anyone out there prove that it can be duplicated. Factory 318s are low performance engines no matter what model year base you start with, good luck with that.

Sustaining high RPM using 'factory' type parts at a 59 degree lifter angle? Sorry, that's wishful thinking. Drag racing, sure, of course but not for long periods of time at varying loads like you say you require.

Guys will argue that "they did it in Trans Am with de-stroked 340s" but those were factory engineered race engines using special parts designed to last one race. And if you research it, there were lots of engine problems where teams had to drop out of races due to blown engines. Longevity had ZERO to do with the program.

Shot peened factory rods, seriously? What pistons are you using? Stock stroke pistons are heavy. Think about what you're trying to do with a relatively heavy rotating assembly. Cast crank? Good luck! Hope whoever balances the rotating assembly can do it to within like a half a gram or so. You'll also need a really good crank balancer unless you want to see what happens when a used factory piece decides it can longer do it's job while you have your foot in the radiator out on some back road.

But if you want to blow through these roadblocks, you're going to want to look into doing some oiling modifications like someone mentioned already. In reality that's merely scratching the surface of your block prep. Sorry but you're not cobbling together a reliable "road race oiling system" with factory ("cheap") parts. OK, maybe you don't need a dry sump system but certainly you're going to want to have a REALLY GOOD OIL PUMP, a good pan with all sorts of baffles and kick outs, crank scraper, maybe even a vacuum pump...

355 V8: the little-known Mopar LA racing engines
 
Also, the 5.2 is generally a hydraulic roller cam so the RPMs are going to be pretty limited with that setup.
 
Think more rally car and less pavement.Without going into details or specifics lets just say I like to drive fast down rough roads many miles from BFN.
Sounds like someone is getting ready for the Rally of Idaho...???? We need to talk! I spent a lot of years and k-miles on-stage in a rally car. Won a couple of divisional championships back in the old SCCA Pro Rally days. Never did a Mopar though I've been thinking about it for fun!

Hoenestly, if I that is the case, I would de-empahsize the RPM's and 100% focus on making a broad RPM range engine. With RWD, you are going to need a very RPM-flexible engine and not a ton of HP; I can promise you that it is not the peak RPM's or Peak HP that counts in rallying; it is the BREADTH of the torque band that counts. You can't put a lot of HP to the ground anyway. The old saying of not being able to put more than 100 HP per wheel to the ground in rally conditions will apply 90-95 % of the time.

And, even though you are starting with a good 5 speed trannie selection, you will not always have the optimum gear in all corners. Sometimes you will get caught 'between gears' and that is part of where the broad RPM range comes in. The other part is that you will always need excess drive wheel torque for the steering of the car that you will want to do with the rear wheel torque.... like a sprint car on dirt. The peak torque has to start at 2500 RPM or lower.

The cooling of the oil is important for sustained hard running like this. I always ran with an oil cooler and remote oil filter. Dry sump is not common in rallying; the cornering forces just are not great enough on gravel. You can do quite an adequate job with pan baffles. And all thinking of a deep sump go out the window; you'll bash it to smither-eens in the first stage mile. So that is part of the thinking behind the cooler and remote mount: a bit more oil capacity that way. Sythethics are a must IMHO; I found that the oxidation of the oil on a rally dropped hugely going from a good quality dino to a synthetic oil. And it can save your engine if you have a sudden leak. (There is a story behind that...)

All the comments of good lower end internals still apply, but with lower RPM's you can maybe sneak by with less. Hyper pistons now become OK and keeping the weight down. If I had to budget, I'd go with hyper pistons, SCAT I-beam rods, and a cast crank. Consider using a not-too-lightened or stock weight flywheel; a flywheel that is not super lightweight comes in handy for setting the car sideways into a corner with a downshift. The comment on on AL heads applies for sure... some Speedmasters would be fine IMHO as you don't need peak HP in this use.

You're biggest area of concentration ought to be the suspension. Are you planning on an A body? We need to talk suspension and brakes....
 
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Also, the 5.2 is generally a hydraulic roller cam so the RPMs are going to be pretty limited with that setup.

I’d fix that with a solid roller cam and upgrade the valve train where I could on a Magnum engine. An Edelbrock Magnum head, the EQ or the new Trick Flow heads would be the upgraded air flow solution.

This would be the best route with a Magnum engine on the cheap IMO. Shy of a rebuild (w/higher compression pistons) or stroking the engine.
 
Title of this should be

Off road race engine.

6 hrs at 6 grand sounds like a long *** dirt road.

I'd guess the motor might last longer than the front suspension.
 
If it is rallying, then it is some hours with RPM's frequently up to peak RPM. You're constantly going up and down in RPM and the gears, with the motor and drivetrain loaded and unloaded. It is not the severe loading that you will get in drag racing (where if you hook up with a lot of torque, then the whole drivetrain is under severe loading). So, due to the limited traction, you can back off on a lot of what you do for paved and drag racing.

If it is off road, in sand, like Baja, then it is a lot of time with the engine and drivetrain heavily loaded. Trannies and gear oils take a lot of abuse whenever you get into sand.

For rallies, the A body front suspension is actually decent, just limited in travel. Longer T-bars is the answer to that Like from a C-body).

The rear live axle and leaf springs needs a complete overhaul and change for rally use; it just doesn't work well at all in rough stuff. The bump steer is bad, the axle is heavier than needed for the power you can put down, and the leaf springs have a naturally progressive rate which makes matching the spring rate and shock rate badly compromised. And again the travel is limited. Something like a stout but light rear axle (like a Toyota /U rear axle) with coil-overs, and a 4 parallel link with panhard rod setup was the best live axle rear setup ever derived for rally use.
 
stock rods are fine, side grind, clean up the stress risers where machined, mil spec shotpeen (not wheelabrator "shot peen")
SPS bolts
bolts were the weak spot
 
How do longer torsion bars increase front end travel ?
It's actually how you should mod the T-bars if you WANT a large travel range AND a suitable spring rate (or wheel rate). If you want to get the spring rate to the range where it is good for rally (which is considerably softer than for road racing) then the shorter T-bars have to be smaller diameter. When you put a lot of travel on those, then they twist too much; the strain in the material gets beyond acceptable limits and you push towards deformation. The longer T-bars proportionally reduce the twist rate and strain.

And I realize there is another part to that question, which is probably confusing the issue.... How do you then mod the suspension to actual longer travel once the T-bars work OK....I have not gotten that far to look to see what has to change around the A arms, stops, shock mounts, etc. But basically the setup is decent for this use. Unlike the rear.....
 
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