Inline six. Torque monster? How come?

Cheaper builds?
Ok here it is price it out yourself. A good 250 chev build. And it is a very good build BTW
1968 307 chev cast pistons .030" Bore block , new cam bearings. Intall 305 vavles , intake and exhaust. Install hi perf cam. I often get regrinds made for these as i have specific needs but you can buy a chev six cam from almost any cam company. Valve springs . (z28 spring which can be bought new for a song.) An intake manifold with at least a 500 Holley 2 bbl (or the newer 250 which has already a good sized carb and dual manifolds exhaust wise. You will have spent so little it will scare you. In fact you are already some thinkking that isnt really a serious build but it is. If you put in a little effort and do some porting as well it gets better. Engine will make around 1 hp per cube and more depending on your cam choice and effort. With serious head work and even more cam it will approach 300 HP and still be reliable.
Ford 300 similar but use 390 cast pistons from a car engine and you must bore 050" which it will take with out a whimper. (Standard bore in a 390 is 4.050" (stock 300 bore is 4.00" ) same for the cam choice. head will actually take 350 HP chev vavles (2.02 /1.60 (or 1.65) A decent cam and you now have a hi compression (relative to the stock low compression engine) performace 300 six. A good 300 ford six will give an unblown 302 a heartattack. Add some head porting and it gets even better. Pistons are in the $12 to $20 range from silvolite although you will have to buy 8 and use two for ash trays. Last 300 Ford six i was involved with ran mid 10s in a t bucket and did it from 1993 to 2008. (Why use the 390 pistons? because they raise the compession, they fit the same wrist pins and they weigh believe it or not exactly the same as the stock 300 pistons. tis what we call a no brainer. Cheap fast easy reliable.
Dodge slant. Several piston choices including 2.2 mopar pistons and even as I have 194 chev pistons with pin holes honed .009 to fit the/6 rods. Same applies. reworked 318 or 360valves most common. Fourbarrels are easy to find and two barrels were stock in later years. A decent cam and springs, a bit of port grinding and on the slant six some head and block planing and you are away . 1 hp per cube quite easy to do More as you extend effort. Effort in a six is up to you. ie If you want to spend a week porting your head you will be rewarded. accordingly. if an hour is all you can spare so be it. Cheap and fun. What is not to like.
Mopar Flathead six?
I have not done any for cars although I have done some for marine use as they are a very popular marine engine and extrmely reliable. Marine engines come with twin carbs stock and a bigger oil pan which puts to rest any crank problems. I used to get a hi perf cam reground on my old cores by an old dude at crane cams in Florida. I forget the specs but these engies were most popluar when done this way. Jmmy Potter of Millar Potter Antique Boat Works in Manotic told me to my face one of those engines I did was the best working Chrysler Crown he had ever seen. His words not mine.
It would be a mild Hi perf street engine for us. I also planed the head and block to gain some squeeeze and did a race style multy angle valve job. When you can buy nothing and cant get nothing then do everything as right and perfect as you possibly can . There is always a few extra pomies to be had with good machine work.
Don

 

I saw a 364 Buick at the machine shop recently,first time I had ever looked at one disassembled.Small valves recessed in a deep combustion chamber,small ports,should be good for lower end power,right? But in the late 50's a guy ran a road course sports car call "Old Yeller" or something like that.He used Buick Nailheads cause they could rev up to 7000 rpm with reasonable reliability and makes 300 or so HP.He won a few races against the Europen big shots when he didn't break down.

 

Gotta jump back in the fray with my 2-cents worth about piston speed. One of the reasons a short-stroke engine usually revs well without self-destructing is because of a relatively low piston speed. They don't have as far to travel, so they aren't subjected to the inertial forces of a longer-stroke engine. At any given RPM, they are accelerating and decelerating much more slowly. Plus, the fact that the rods and pistons are generally lighter also reduces the destructive forces at work.

 

Truckedup said:
"I saw a 364 Buick at the machine shop recently,first time I had ever looked at one disassembled.Small valves recessed in a deep combustion chamber,small ports,should be good for lower end power,right? But in the late 50's a guy ran a road course sports car call "Old Yeller" or something like that.He used Buick Nailheads cause they could rev up to 7000 rpm with reasonable reliability and makes 300 or so HP.He won a few races against the Europen big shots when he didn't break down. "

Excuse my ignorance, but can someone explain how small valves contribute to low end power or torque? ...I've always heard that that's ,at least partially, why "nailhead" motors are known for their torque but I never fully understood why. Thanks.

 

BeatnikPirate - The small valve thing has to do with optimal airflow at a given RPM. Engines with hugh valves and ports usually don't run all that strong at low RPM's, because the air flow doesn't have enough velocity. This might not be a big deal on an EFI engine, but it's huge on a carbureted engine, where the air flow is also carrying the fuel along with it.

 

So, in other words, the mix coming into the cylinder is coming in at a higher velocity because it's being forced thru a smaller opening,(smaller valves and/or port passages) but at higher rpms the total amount of flow volume is limited by that small opening? That makes sense. Thanks.

 

Don't pick an 'average' L6 if you want to build a tire-burner. The Chivvy 250 and 292 have SEVEN main bearings that hold up in the most extreme builds. They can be built to compete with ANY V-8 of equal weight.

 

Honestly, most later model straight 6's have more mains to support the longer crank...not just "Chivvy" Ford did the same in '68 or so. And...frankly, any straight 6 can be built to compete against any V-8 any day...no matter the make

In my non professional, non numbers backed, backyard mechanic opinion, the reasons most bigger trucks have, or had straight 6's is because they made torque at lower RPMs typically. Less RPM's means less wear, typically, on the rotating assy, bores, bearings, etc...That means less working on it, less money into parts, and less in gas depending on the build. I admit, I too fell into the illusion that L6's offered "more torque", but it is a grand illusion based on RPMs and MPGs that people associate them with. They produce more torque that is streetable, as it has been said before by a few people. They are some fun engines either way, and I want to build one.

On a non related thought...why does every engine thread have to mention SBCs when nobody was asking about them? This thread was about inliners being torquy I thought? I guess thats what I get for thinkin.

 

Yep. I hear that! I don't 'compete' on a large scale. But, I like to 'joust' with other rides in traffic. Whilst driving home from the Abbey Car show at Canon City on Saturday it was quite apparent that the L6 in my ride, and the one my son was driving could compete with the V-8s. There was a whole covey of other 'rods, it was obvious that they were challenging us, they had passed us on the way out of town, waving as they went by. Then, low and behold, whilst climbing the hill three of them peaked out and my son, in front of me, honked his horn, inviting them to merge right so that he could get around them. Whilst climbing that hill we walked away from them........

 

IF you can keep the flywheel from shaking loose. And I'm not joking about that.
Larry T

 

Do some Youtube searching and look for the inline 6 that pushes 1,000 HP. They show the dyno pulls, then they kill the lights. I swear I thought the thing was going to blow apart!

 

Oops - I didn't mean to pick on the sixes. Just stating what I believe to be fact. However, one of the funnest things I ever drove was an I-6. Years ago I worked in a body shop and our parts truck was an early Falcon Ranchero with a little six and a factory 4-speed. The six had a cam and headers and was a hoot to drive. I'll have to admit, it didn't have a lot of low-end and did rev pretty good.

 

29 Nash. You gotta love those moments. It is interesting this thread because i have had a couple of phone calls on this very subject since fri.
One was from my pal Paul Amado in Kitimat BC. Paul runs a strong BB Demon and bought his daughter a car to run. It has a warmed over /6 and is a pretty serious piece. Paul finished the car and redid the suspension drag style. (SS springs pinion snubber etc etc. 60s style so to speak (stuff the really works.) A race was organized there involving some of high school age. All his daughter's friends told her she could come and race but really would have no chance against thier new Mustangs etc etc. Undaunted she showed up and did her poppa proud. Won the whole dang thing with a 9.0 flat ET for the 1/8 mile. Paul said he asked her what her friends said the following monday after the race. She told him "They said absolutley nothing." I guess it is hard to speak when youre eating crow.
Personally I live for days like that and reports like that. It is what makes me tick i guess.
Don

 

Also this seven main bearing thing. Nice but you forget all of your V8s have two cylinders between each main and it isnt even a concious thought that is not good so dont get yer nickers in a knot cause a slant six or 235 chev etc only has four mains. Tis all that is required son. If you dont believe me all those with a four main block that broke or a busted crank from a four main block , please stand up. Sorry i dont see anyone. It must be foggy or something.
Don
If there is one rule we as rodders need to learn it is MORE IS NOT ALWAYS BETTER sometmes it is just more.

 

Wow, dont tell that to my '63 Grumman, just spent the last 5 weekends spinning at 3K rpm all over SC and GA!

 

I personally know of two broken crankshafts. The first was a Chev 235 six. The second was a Ford 331 V8 in a fire engine. It happens, regardless of cylinder count. But I would expect to see way more broken V8's because they are usually the ones that get all the serious abuse.

 

The piston will obviously be completely stationary at exact TDC, and exact BDC no matter what.
But with the crank pin at the exact point of 90 degree crank rotation, the angle it makes with the con rod can vary considerably with rod length.
If the rod was a mile long, it would make an angle of maybe 89.9999 degrees with the crank pin and be almost vertical.
If the rods were so short they were only half as long as the stroke, the con rods would be almost horizontal in the bore.
For any practical con rod length, the rods will be at some odd angle to the crank pin when the crank is at ninety degrees. So the piston can never half way up the bore with the crank set at ninety degrees. It almost will be with a very long rod. But with much shorter rods, the piston will be further down the bore at half crank revolution.

Now if the piston is maybe only (say) a third the way up the bore at half crank rotation, it must travel twice as fast between there and TDC. To cover twice the distance in the same next 90 degrees of rotation . That is pretty extreme, but you can see how that works with a very short rod.

What this means is the piston travels a lot slower either side of BDC, and a lot faster either side of TDC the shorter you make the rods.

 

Hmmm,looking at a 4 main 6 cylinder crank I see 2 crankpins spaced the width of the bore spacing (about 4 inches) between the mains.Looking at a V-8 crank I see one crankpin with two rods side by side toucking eah other between the mains. Which crank is more likely to flex? you tell me.
That being said,I doubt broken cranks are a problem at the power level most 4 main 6's can make.
One thing missing in all this is cubic inches,a 4x4 6 is 300 cubes,a 4x4 V-8 is obiviously 400 cubes.So figuring a mild 6 inline street build is about .8 HP per cubic inch on a good day.............
Will an average guy working in his garage be able to get a better build per dollar spend on a 300 cube 6 or a 300 cube V-8?

 

Warpspeed - Well stated. I even understood it, although it did take two readings before it sunk in.

 

Indeed!

Can I guess that, given a leaking valve or piston ring takes time to occur, that a longer rod with a faster TDC speed would be better? Less time for leaking, since there is no perfectly sealed ring or valve?

 

Tis true there is no space but those old cranks are pretty stout too. neither though is likely to break.
Don

 

The main thing with cranks is torsional vibration.

Longer cranks whip more, and twist more, and are very bad news for high rpm.

That is what killed the straight eight, and the inline six is dying.
All the auto manufacturers are now going to V6 engines, because thy are shorter, and the block and crank are much lighter and stiffer. A short stiff crank reduces torsional flex, and is a far more suitable design for modern high revving engines.

 

BMW still make very hi output inline 6's.They are smooth and some versions rev to 8000 rpm.
I may sound like a die hard V-8 guy.....But got into inline 6's and was a long time member of the Inliners club before the internet. Me and the wife both have Jeep Cherokees with the inline six as daily drivers.That old AMC 6 was the last US OHV inline 6 made and it might have the most power potential of it's size.I built a few 235-261 Chevys and a 302 GMC powered 37 Chevy PU that is now owned by a Hamber.A lot of fun building and beating on the old 6's for a backyard hack like me..Ya just have to be realistic about what to expect power wise.Obiviously the newer Chevy and Ford 6's have good potential,and being 300 cubic inches is better than less cubic inches.
Yes ,flywheels on inline 6's can loosen,red Loctitie used properly will be ok on street engine.
The V-8? A few years ago I built a SBC for my El Camino.A lowly roller cam block 305 I got for short cash.Put it together with a little more cam,compression and carb. And like all SBC's it's easy to make power,and it's inexpensive.And that V-8 sound!!! I been seduced and want more

 

I enjoy both. Spent yesterday morning working on my slant six rail . I made a carb adapter from a four hole spacer and had to mill it on an angle as I had set my motor upright enough so it didnt hang over the side frame rail but when I installed the four barrel intake instead of the 6 singles the carb did not sit level and that bugged me. .Finished that fired it up and listened to it rummpty rump for a while. Then I backed out my 63 MAX wedge car, washed it and went for a drive to a friends house abusing it at every opportunity. Sure tis fun to roll along about 15 to 20 mph then wack it to the floor and watch the car lift as the trans downshifts to low and then promply in a very few short seconds makes the two shifts back to high. Almost but not quite as fast as you can push the pedal . If my wife was with me she would be screaming but she wasnt . I thoroughly enjoy both 6s and V8s. It is not for me either or. With the 6 rail it is a challenge. You establish the parameter when you pick you engine and you stick with it to see what you can get from your combo. Sort of like self imposed class racing. Little by lottle you wittle away at the ET. Since you have established the parameters it is not a big money thing, more like a enjoyable hobby. Like fly fishing. Sure you could get more fish with a stick of dynanite but that is not the point of the whole fly fishing excersise. Running a six is similar. you do it for the fun and the challenge. And when you need a neck snapping ride you just go to the other side of the garage and hop in and fire up the mighty wedge. It works for me anyway.
Don
http://www.dropshots.com/Dolmetsch#date/2010-04-17/18:45:13
or
http://www.dropshots.com/Dolmetsch#date/2006-10-30/20:44:48

 

Things seem to go in cycles. Back in the fifties, most of us couldn't wait to ditch the old anemic sixes and go for a V-8 due to it's sound, it's performance potential, and it's assumed superiority of design. Today if I see a hot rod or custom with an inline six, it stops me in my tracks just because it's different, it's nostalgic, and I like the way they sound and look. Low end torque could sometimes be just an added bonus.

 

Lets remember that the latest genoration Chevy pickup sixes are inline DOHC. GMs reason was said to be cheaper to make. It looks like a pretty good potential race motor. Dennis Varni has one in his new streamliner built by Cub Barnet

 

Back in the 50s I ran a flathead Dodge L-6 motor on dirt track. Didn't consider a V-8 then. When I talked about what my motor needed, a good old mentor told me; "you have enough motor, you need to work on your drivin'"..............

There are a dozen ways the inline is more practical for me.

I can change out the lifters & adjust the valves in an hour.

I can replace the exhaust and intake gaskets on my L-6 three times as fast as on a V-8.

One stop exhaust.

Carburetors out in the cool, free air.

The longer block is easier to accomodate to a hot rod than the wider V-8 when it comes to steering box placement, headers, etc.

On many V-8s the headers are so tight that the spark plug wires get cooked.

I'll never build a V-8.

 

About busted crankshafts;

All vibration is best delt with by a combination of balancing, dampening, and determining rpm red-line.

I don't know the statistics, but it's my gut feeling that on high performance builds the incidents of busted crankshaft is no more predominate with L-6s than with V-8s. It's my belief that most catastrophic motor failures are due to inadvertent over-rev, or detonation.

I'm guessing again, but believe that more crankshafts are busted in the development/experiments than in service. People learn the limits and go with that. The limits/'redline' on my L-6s is the valve train. They simply won't rap any more.

 

Ive got one of those carbs in my shop! And i thought it was my idea. Dang!
Don