Here's one I bet nobody's done... probably with good reason, but I'll leave the link below to what it is so you can scoff and convulse in disgust... before that though, let me give you the reasoning before that. The inspiration for this idea is a guy known more for his love of MOPAR but he used to be a writer for several different car magazines named Tony DeFeo aka "Uncle Tony". Tony is currently doing a 170 Slant Six swap on a '93 Miata for four reasons.

1: Because it's a challenge
2: Because the 170 Slant Six is, as the engineers who designed it called it, the "Perfect Engine" and is known for its reliability, durability, and it's circle track record as being one of the best in it's class.
3: Because all in the vehicle should weigh about 1,850-1,900 pounds with a reliable 150hp engine that can basically LIVE at 7k all day long while being a good daily driver.
4: The simplicity of the engine as well as the systems that support it (electrical systems that is) are easy to trouble shoot and fix with basic hand tools and very few spare parts.

Straight six engines are the smoothest, and probably most durable engines around because they're naturally balanced due to how they work. That said, it should be possible to build the engine in the link to perform relatively well, and with the right transmission and induction system, it could potentially be a very good swap for the F-Body. It would weigh less than a SBC, provide more power than the stock 305 even if only modestly built, behave well on the streets while still being capable of revving very high for long periods of time provided the oiling system is sufficient. If built a little less than modestly, these engines are easily capable of 300+ horsepower with 300+ ft/lbs of torque while not giving up too much of their drivability.

Now, the reason why this isn't as crazy as it seems is because they were also used in the Second Gen F-Bodies, so theoretically it should fit under the hood no problem. Mated up to a Six Speed Transmission, and fabricating an intake manifold to accept multiple carburetors (Offenhauser used to make a triple single barrel carburetor set up for it) it would have some real potential.

AND the best part is that the donor engines seem to be pretty cheap even if they are a little harder to find.

292 straight 6 chevy motor transmission - $400 (Pulaski) | Auto Parts Sale | Syracuse, NY | Shoppok

 

See, this is a great example... this is a 292 bored over to 298 with a custom triple carb set up and headers going into a drag race Camaro. Unfortunately there don't seem to be many other videos of this thing, but apparently these things are pretty commonly built by the old school hot rodders. Just never seen one in a Third Gen.

 

Another good video of a slightly smaller one of these engines (250 cubic inch) in action in a 65 Chevelle Wagon. Sounds good, and surprisingly pretty quick from a dead stop towards the end of the video.

 

Triple Webers = Six intake openings
Six Cylinders
Six Speed Tremec T56

Oh my God.

 

IMO, it's 2 cylinders too long to fit.

 

No replacement for displacement. You'll spend the same money on a slant six as you would on a 350 for 2/3rds the power.

 

I don't know... they DID put the Chevy Straight Six in the 2nd Gen F-Body, and you'd probably NEED to use an electric fan, but I think it would fit. I'm actually more concerned with how tall it is honestly.

It's not a slant six though, it's a 292 Chevy Inline Six, and while you're right, and I already have a 350 that probably will end up going in the Trans Am, I just think it would be neat.

 

should be a decently easy swap if the usual inline six trannys are used-I see no need for a six speed,but would expect to see a "three on the tree"3-speed shifter I think the 1979 Nova was the last car to use the inliner-trucks could have it through '84.

 

Yep. Been watching Uncle Tony for a while now. Too bad no room for heater & A/C now...

 

Yeah... but... like... Six Six Six! I'm going with a theme here, man! lol

Yeah, that's something I'd like to have personally. With his Miata though, he had to cut a big dog house out to fit that Slant Six... I shouldn't have to do that with a Chevy Inline Six. However, unlike his Miata, I probably won't get it all behind the front axle centerline (F.A.C.). From what I've seen so far of the Second Gens that have it, about 25% of the weight or so will be in front of the F.A.C. which won't help handling since that's more as a percentage than the SBC, but total weight wise it's probably comparable.

If I did do this though, in the spirit of keeping it like Uncle Tony's Miata, it would definitely want to keep things as simple as possible. So I'd probably forego the A/C as well. Working on my G-Body wagon trying to trouble shoot the stupid HVAC system (the vacuum actuated doors don't work and it's being a pain in the butt to figure out what the problem is) I think it'd be nice to have a car that has literally only the bare essentials... heater core that puts air into the windshield and to my feet during the winter (I doubt I'd even drive it during the winter honestly) is all it absolutely NEEDS. But... A/C would be nice. It's something to think about. A/C systems aren't THAT complicated.

 

A Straight six swap was done using the GM Vortec 4200.

https://www.thirdgen.org/forums/engi...ec-4200-a.html

As far as power goes from your slant six against todays engines? Modern SBC parts, or moving to Gen3+ would destroy HP/$ ratios.

As a conversation piece sure, an engineering exercise sure. But as a practical swap? Not so good.

 

Okay, that's pretty cool! I was actually looking at 4200s because I just became so intrigued by the straight six idea. You're probably right about the practicality of it, but I do thoroughly enjoy the idea of an engineering exercise and conversation piece. Plus, from what I've seen it's possible to get some decent power out of a 292 or even a 250.

Either way, once I've got my G-Body wagon out of the garage (as mentioned before I'm having some HVAC vacuum issues that I'm trying to troubleshoot) the next thing to do is some maintenance on the B-Body, and then the F-Body will go in and I'll start hammering away at it. More likely than not, since I already have a 350 SBC on hand, that's what'll end up going in, but MAN this inline six idea has got me feelin' funny! lol

 

If you swap a SBC into a 2nd gen f-body that had a 250 inline six, you will have nearly 1 foot of room between the front of the engine and radiator. You need the huge elongated fan shroud and very long fan spacers to get the fan blade in the proper position. Unfortunately, that swap does not work the other way in a third gen.

 

You can turbo a 250/292 chevy as well

 

More likely than not the space from subframe mount to firewall will be about the same though. Even if there's less space between the front of the engine and the radiator, that might still be fine, it would just need an electric fan instead of a mechanical one. It's a sacrifice in the sense that it eliminates some of the simplicity that I want, but instead of setting up the fan to use relays and a temperature controlled switch, I'd probably just put it on an on/off switch on the dashboard or do a dual fan set up with one fan like that and another that turns on with ignition hot and is always on when the car is running.

If there IS enough space for a mechanical fan then... well... I'll go with a mechanical fan.

Neat, but I'm staying away from Turbo and Superchargers. Always have, probably always will... maybe someday that'll change but not this time.

 

There are at least 2 replacements for Engine-Displacement...

-Positive Displacement Pumps and Compressors (Superchargers and Turbochargers)
-Nitro-Methane

Both are excellent replacements for Engine-Displacement.

 

Welllll... I mean, if you did either of those things to a larger displacement engine then you'd definitely get more power out of it lol.

However, I will say there's a limit to how much displacement is going to help you. Some engines are just incapable of getting up into the high RPM ranges because of reciprocating mass, engine imbalance, valve float etc etc. You're never going to make a decent race engine - or even a decent engine for a land based vehicle at all - out of something like a diesel engine out of a submarine, and it has more displacement in one cylinder than most of our cars have in total lol

So there's a balance to be made... bore to stroke ratio, volumetric efficiency, valvetrain stress, yadda yadda yadda... generally speaking, the 250 I6 is good because it has larger bore than stroke, is naturally balanced since it's an inline six, and with some upgrades to the valvetrain (roller cam, higher tension valve springs, roller rockers) and flat top pistons it can be made pretty competitive. It might not be as cost efficient as a SBC, nor will it put out as much power, but it'll more than make up for that in reliability, durability, and simplicity. Plus, I think an I6 is the only engine out there that comes close to rivaling the sound of a V8.

 

Power is in the intake, head, and exhaust. The rotating assembly is there pretty much to just rotate. New SBC, and new Gen3 is just so much more efficient and better that you can cram alot more intake charge through smaller more efficient ports. Better chamber designs promote more complete burns without detonation...etc.

So many little things that the SBC has continued to receive where other older engines are still on factory castings from 50+ years ago.

There is a reason that when GM designed the Gen3 SBC they ditched the center intake/exhaust ports. Bad design. the new (old if you look at SBF) design allows for much better port shapes. So many little things that add up to massive gains.

 

I am going to use a LS2 and a LS7 for examples since the Gen-III/ Gen-IV Engines are so popular here.
With the Gen-III/ Gen-IV Engine Family... the Stroke length, the Connecting-Rod to Stroke length, and overall Engine displacement are not going to have a major effect on RPM potential.
I know that it is a common belief... and to an extent this is true as Piston speed can become too fast... but it is not an issue in regard to the common arrangements of the Gen-III/ Gen-IV Engines.


The overall deciding factor in this case, is the Valve-Train... and especially the Valve-Springs.
The weight of the other Valve-Train components are a factor, as lighter weight components can allow for high RPM...
But it really comes down to the Valve-Springs.


The LS2 had a shorter Stroke and less displacement than the LS7.
However the stock LS7 can rev to a higher RPM than the LS2...
Yes the LS7 has lighter Connecting-Rods.
But this was done for engine longevity and not really for RPM reasons... The Camshaft and ultimately the Valve-Springs are what dictate the RPM attained.


Now in regard to forced induction...
What do you think occurs as Boost Pressure increases? Lets say to 14.7 PSIG.
That is double Atmospheric Pressure (at Sea-Level in a perfect world).
Without taking efficiency into account; that is double the amount of Atmosphere entering the Engine compared to being naturally aspirated.
Essentially that is practically the same as doubling the Engine displacement.
A worthy replacement for "actual" displacement.


Next, Nitro-Methane...
Essentially this is a fuel that can carry its own oxygen source.
This allows for a significant amount more fuel to be burnt.
Without getting into the details... this fuel allows for an Engine to produces 2.5 times the amount of power verses burning Gasoline.
This is also a worthy replacement for "actual" displacement.

 

Now, come up with a replacement for the cubic dollars it takes to replace those cubic inches, and I'll be suitably impressed

 

Sometimes it seems the unconventional swap idea is one that's easy and works really really well.

 

Yeah, but where's the fun in that!?

 

I never see anybody doing a SBC with SB2 heads. Do people just not know about those things or what?

 

Do they fit on a gen 1 SBC, or is it a special block?

 

At some level, this sort of thing has to move from chicken-choking into REALITY.

OP, when you have done this, come back and report. Meanwhile, you're going to get 2 kinds of responses:

1. Cheerleaders (yay! it's your car, you can do what you want! SBCs and LSxs have been done to death! Do something oddball! blah blah blah blah)
2. Common sense people (there's often A REASON why the unconventional is ... unconventional. Maybe that/those reason(s) don't apply to you; but you'd do DAMN WELL to examine all of that FIRST, before jumping on it.)

Per the 2nd point, I'd suggest talking to all the people currently winning races with that old POS tractor motor POS, and see what they're doing to make theirs so UNBELIEVABLY fast. Like, how they take a motor that the crank would break if you ran it over 4000 RPM for an hour, and zing it up to 7000 and beyond without trouble. Look back in the 60s and early 70s when that POS was on the street in its MILLIONS and see how many people were using them to beat 440s, Hemis, 360s, etc. Let alone, Frod & GM motors. (this of course, was before Europe and Japan had recovered from WW 2, and Korea, China, etc. were still largely in the Stone Age)

Until you have done that kind of research, I strongly advise you to lay off of magazine-article bishop-buffing, and rejoin The Real World. Or, shut up, and PUT UP instead.

 

Never looked into it myself but Scoggin Dickey claims you can with the right parts.

 

BTW, re. the SB2 question: yes AFAIK they will "bolt to" a traditional SBC block. That is, the head bolt pattern is the same. (on some of them at least) There are problems with rockers, lifters, push rods, etc. when doing so however. Not sure how or even if those can be overcome nowadays but the parts used to be available at least. Dart, maybe others, made aftermarket blocks for them as well.

The head bolt pattern (5 around each cyl) was one of the greatest strengths of the SBC back in 55 but eventually turned into one of its greatest weaknesses as gasket technology improved, which is probably why the SB2 never really "took off". The Frod small block & 351 Cleveland (arguably one of the best designs of the 60s), BBC, LS, and lots of other motors only have 4 bolts around each cyl; which allows MUCH better intake port configurations.

They were never used in any kind of "production" motor, strictly racing only. They made more power than yerbasic 23° SBC due to the straighter intake tract. Not hard to see how that would work. Chambers in most of em were REAL small, like 40cc more or less, which is great for high compression on pure race gas but not so good for the street. There were acoupla versions of them, some with identical cylinders & ports, some with mirrored like the old SBC. I don't think there were ever more than some hundreds of sets of them, maybe acoupla thousand, ever in existence; parts demand and whatnot is therefore VERY low, therefore parts availability is even lower. They were only used for a few years in various sanctioned factory-involved series such as NASCAR. I don't think they were ever popular in WOO, any kind of drag racing, SCCA, etc. but I could be wrong. At least I can't ever recall seeing them on sprint cars.

LS motors are altogether better in a number of ways. AFAIK nobody uses the SB2 or SB2.2 anymore. There's A BUNCH of "spec" series nowadays that use some one or another LS motor with the fasteners sealed, no matter what brand-specific trim adornments the chassis might sport. ASA is a good example of that. Their "spec" motor is almost streetable, can be made reasonably so with little effort in fact, which is why the ASA cam variants are so popular. The tracks that those cars run on aren't so different from lots of real-world streets.

 

Remember the Coates Rotary Valve head? No valvetrain limitations, just whatever your short block can withstand.

 

The SB2.2 heads still showed up in the Chevy performance catalog as of 2019. Always been curious about them. Catalog also shows a block that will accept the heads

 

I'm waiting for the "Cummins 6.7 Turbo Diesel swap" thread.

 

Well, somebody already did the GM I6 swap as mentioned earlier in the thread... GM is coming out with a new I6 Diesel this year for it's trucks so it's only a matter of time I think.

I don't know man, I don't think I'm on the cutting edge of any kind of trend here, but the more I look into straight six engines, the more I realize how great it could actually be. They have a few flaws that take away from performance, but they can be mitigated, and the simplicity as well as the reliability just way more than make up for it. Plus, just yesterday ALONE I found like 4 or 5 Chevy Straight Six motors for under 300 dollars in neighboring states to where I live. They're out there, they're plentiful, and they're cheap.

 

The very low load factor of 140 Hp is what makes that engine reliable. Uprating will take that away in a jiffy.

 

lol I just read this, no idea how I missed it before but why are you so angry, brother? Like... DAMN!

Listen, I agree. Until it's out on the road it's just a fantasy, a pipe dream, a thought experiment... looks great on paper but no telling how it'll work out in the wild. And, like I've said a couple of times already, while I really wanna do this swap for the sake of doing something different and trying to make the most out of something a lot of people look down on and still have FUN (that's why we're all here, isn't it?) I still might end up using a SBC because I've already got one of those. I've also got a Pontiac 400, and a 3.8L V6 and plenty of transmissions. I've got a penchant for the underdogs, I love this kind of stuff. The goofy, the weird, the overlooked. So please bro... please...

 

I've looked into it. Its the difficulty/expense of the heads/intake system.

I've looked at these heads before too. If I could find a nice intake that would fit under the stock Firebird hood, or a very small bulge like the RA1 I'd go for it.

https://www.profilerperformance.com/...ree-heads.html

With those heads you'd want a .700"-.800" lift valve because that's when they finally level out and running anything lower than .600" be leaving a ton of flow on the table. But we are talking almost 400cfm by .600" and over 260 on the exhaust.

These heads would feed a 383, or 396, or 400+ block easily into the 7000rpm range. Or they could feed a 350 well past 8000rpm. And with modern VT components, a 8000rpm VT is attainable with Hydraulic lifters. You'd end up with a shaft mount system, but that would immediately take care of any deflection from the a stud based system and the rockers would be perfectly aligned so they didn't wander across the valve.

The problem with those heads is the intake side of things. The exhaust should be doable.

 

The more things change, the more they stay the same. Take a time machine back to 1996, open up Thirdgen.org and you could probably find a thread nearly identical to this one. Maybe the key players would be different. The OP would have a different name, the subject would be some other engine, but it'd follow the play book. Like the man said, cheerleaders (both serious and sarcastic), and common sense replies suggesting alternatives, with the inevitable reply from the OP to stop being negative and raining on his parade. It'd almost be nostalgic if it were a fond, sentimental memory, but it's more like a flashback to something really cringey.

 

I'm sure there are threads like this in literally every car enthusiast forum known to man, throughout every era of their existence. It's just nature taking it's course lol.

But hey, those replies to stop raining on the parade don't typically come (especially from me) unless somebody sounds like they're just trying to be as big of a [feminine product used for intimate cleansing] as possible for no reason at all. Nobody needs them negative waves... why can't guys like that just say something righteous, and hopeful for a change!?

But it's whatever, I've been a forum jockey since the early 2000's, so I'm used to seeing guys sound violently angry over stupid stuff all the time. I know they aren't actually mad, they're just trying to show everyone they've got the biggest pair of cojones in the room. Nobody cares.