I've heard many people say the slant six rods are forged steel like the crank but I can't find anything on the internet that proves this. Is it a high hope or is it true? A confirmation source would be greatly appreciated.

They are forged, but without analyzing the material we don't know what they are forged from. You can tell a forging from a casting by visual examination. Forged parts have wider parting lines than castings and a different surface finish. Also, cast iron rods are relatively rare. So it's not wishful thinking nor is it uncommon to have forged connecting rods.

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Joshua

Thanks, maybe I'll send one off to a metallurgist to have it examined. I'm trying to explain to a few other gear heads I know why the slant six is one of the most cost effective engines to build for boost because it has a forged crank and rods.

Knock yourself out, but it's completely unnecessary. The rods are plenty strong. There are boosted slant six cars running nearly stock bottom ends.

You're likely to lose this argument not because of engine strength issues. There are plenty of engines strong enough to survive a lot of boost. What kills most boosted engines is not related to rods and cranks, but fuel management. To get a really good fuel system on a slant can cost a lot. We don't have an EFI manifold stock so you have to fabricate one. Slant six cars and trucks don't have high pressure fuel systems so that has to be fabricated or bought. We don't have electronic engine management stock so that's something else to buy, install and tune. So what if you didn't have to buy a $600 set of rods? You blew a lot more than that to get a fuel system and engine management plenty of other engines were born with.

Also, don't send the whole connecting rod. Cut a little bit off the balance pad and send that to the lab.

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Joshua

there are other limiting factors as well. even the cast crank motors will handle almost all the power you can get from the stock head and there is no aftermarket improvement available.

Well using a 350 as an example (because it's probably the most common engine built) building one for boost with fuel injection, coil pack ignition, roller cam, and a fully forged rotating assembly would cost around 7k or more and that's using vortec heads and a cheap turbo.

The slant six (from the pricing I've done) would cost about 5k for the same. A big factor is that it already has forged crank and rods which saves $800-$1000. Gill welding out of georgia makes a multiport injection kit for $1400 which is actually on the cheaper side as far and multiport injection goes. Yes the atomic efi is $1200 but you have to find the four barrel intake which is rare and usually more expensive.

I talked to a guy in australia who converted his slant to a coil pack ignition for around 1k USD which is what the 350 conversation costs from msd. I recently found a roller cam for $800 from LSM Engineering (they don't have many left and they're not making more) which as far as rollers go is pretty par for the course as they're made from billet steel, and lastly a set of forged pistons for a slant runs around $500 which again is par for the course.

Obviously the V8 is going to make more power but the slant is something like 150lbs lighter and you're likely going to be putting it in a dart which is around 3000lbs curb weight and can easily be made lighter.

So on paper it it would seem that the slant would be more cost effective thanks to the growing aftermarket. There's even a guy in some of the slant fb groups designing an aluminum head. He's already gotten the combustion chambers milled out in the last photo he posted. Though you could always hog out the slant head to flow 200cfm which for a six cylinder is respectable.

The slant I'm building is aimed more at seeing what they could have been in a modern production car if chrysler never gave up on them though I plan to build a twin turbo version with a hot cam sometime in the future.

Your assumption on the need for, and the expense of, a forged rotating assembly isn't true. The cast Chevy crank and powdered metal rods do fine until you start making quite a lot of power. H-beam rods can be had for less than $250 if you need more strength. I have been wholly unsuccessful at buying a set of used 7" slant six rods for that money. Buy a Gen 3 or 4 Chevy engine and you have individual coil ignition and EFI hardware for dirt cheap. Go watch Richard Holdener on YouTube and see what power you can make with a junkyard LS bottom end. If you really want one port EFI 350s exist too. I own 2 of the Gen 2 LT1s. They're cheap and the F and Y body versions are aluminum headed. My 6-speed '94 Corvette cost me $4k two years ago and just needed tires and rear shocks.

If you want the same power the 350 is far less expensive than a 225. Also, a 225 is only about 65 lbs lighter than an LA 318. How do I know? Not the interwebs. I blew up the 225 in my race car and built a 318 to replace it. The 225 had a Clifford intake and headers with an aluminum bellhousing. The 318 had 3 iron manifolds and an iron bellhousing. The car gained 80 lbs at the scales. And a Chevy small block weighs less than a 318! I'd bet you my Corvette's LT1 with AL heads and intake weighs within 30 lbs of a 225 with an aluminum intake.

If you really want to see where Chrysler could have gone look at other I6s like the Mercedes M104 or any other late 1990s I-6 from BMW or Toyota. The 3.2l M104 makes right about 230 hp in luxury car tune. Look at the M104 intake manifold and tell me how you bring that level of engineering to the 225. Look real close and then see if you can tell me why the plenum is divided. It's that way on the late M104 and the naturally aspirated Toyota 2JZ, but easier to see on the Toyota. The M104 already has dual exhaust manifolds. BTW, I'm waiting on delivery of a wrecked 1996 Mercedes S320 with that 3.2 L M104 engine and a 5-speed automatic for $1000, running and delivered. If I want to turbo it I can change the head gasket and put in head studs and it will live in the 500-600 hp range. The 5-speed auto is the 722.6 which Chrysler used in cars behind Gen 3 hemis, but called it the NAG1.

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Joshua