Turbo-Thrift 6: Any Ideas and Experience?

I have this 250 cubic inch (4.1 Communist Volumetric Units, or CVUs) lump of cast iron that a buddy of mine gave me, out of his 74 Camaro. Apparently it's painfully stock- supposedly it even has the head gasket that GM put on it in 1974. 

I know nothing about these engines.  Wikipedia tells me it makes 100 HP at 3600 rpm, but it also has 7 (!) Main bearings. So, it's basically a hugely understressed BMW engine. Can I spin it faster, and make more power?  

I will also need a transmission for it. The engine does have a clutch plate on the flywheel, so that's a plus. Maybe find one of them 4 speed OD transmissions GM used in the 70s?  Or will a T5 or something mate up easily?

Oh, and then I need to have a vehicle to put it in. I mean, eventually.

Another inline convert!!  One of us! One of us!

So, Clifford Performance is the "easy" button, but the company has had some ups and downs since Jack died almost 25 years ago.  His kids were running it, not sure if they still are?  Check current reviews on service and customer support before you buy.  Parts should be fine, but from them the cost is higher.

Kay Sissel used to do parts for them, I think he or his shop is still around.

You can easily make them make power, but semi-realistic goals are important.  The cost will never be as low as making the same power from a SBC or whatnot.

In reply to Mr_Asa :

Bangshift has a video where they built one up fairly cheaply to make 320 HP.  With the stock 250 head. 

https://bangshift.com/bangshiftapex/built-chevy-250-make-320hp-on-the-engine-dyno/

My research shows there was a 250-S used in some Brazilian market cars that made around 170 HP.  This being a "factory" build, I assume that's pretty conservative.

I do have a set of headers that came with the engine, and the engine donor apparently just stumbled over a 4 bbl intake, which he's also going to give me.  Fortunately, this is a '74, the last year before the integrated head/manifold b-s.  I also have an HEI dizzy that came with it.  And a Delco alternator!  

So I think I'm most of the way there.  Mostly just need a cam that will groove at something over 33-1/3 RPM and a teeny tiny 4 barrel fuel atomizer.  

In reply to volvoclearinghouse :

I love the torque "curve" on that video.  Thats what these things do best.

Richard Holdener has a couple videos on that engine (292, actually, I think.  Same difference. ) and Powernation did a build with a 292.  Pretty much any of their tricks should be applicable. 

Brazilian market has loved the inlines almost as much as Australia does.  Done a lot of weird things.  Lots of inspiration available from them.

Boost!

https://www.12bolt.com/store/p118/Turbo_Manifold.html

https://www.12bolt.com/videos.html

I think it has a regular SBC bolt pattern so trans choices are easy. T5 from a 80's Camaro should work easily with a matching bellhousing. Or use a Doug Nash 4+3 if you want max strangness. NV3500 from a 90s truck would be easy too, but its not a sporty transmission.

I second Boost.  The great thing about modest boost is you only get it when you need it.   Cruising down the highway you'll be making trivial  if any.  
    High mileage (75,000+ miles) stock bottom end doesn't even need to be opened up.  (as long as compression is OK) 
stock everything is all you need. 6 psi should get you 40% more power with an EBay /Amazon new  Turbo ($130)  depending on if it's set up for EFI you'll need to spend a few more dollars but all done you'll be under $300   You can probably survive long term 10-12 psi  with unleaded premium. That will  give you close to 300 hp from a stone stock unopened 250 cu in  six.  
  I've a friend who is approaching 50,000 miles untouched with a similar set up. 

In reply to volvoclearinghouse :

A cam is a trade off device. Trade bottom end power to gain more at the top end.  It's not a power adder like a turbo is. 
      Turbo might sound scary but I doubt you'll have any real problem.  Plus!!!! It makes tuning very simple.  Punch a couple of buttons in your lap top instead of taking the carb apart to change needles/jets.  
   Stock stuff can easily handle modest amounts of boost.  In fact it's actually easier because the connecting rods are weakest on the intake stroke. ( only the rod bolts hold it together)  where  there is added load ( on the power stroke)  the rod is built strongest that way. 
   Modest power ambitions yield the most reliable engine.  The 10% ethanol helps keep the engine cooler and if you're doing a lot of hilly load hauling you can go to 88 octane (15%  ethanol )  for additional cooling.   Switching to E85 is going to give you the most power and coolest running. It's only a few key strokes away. 
     Finally you can get the engine running on whatever set up you have.  And switch over to turbo once you confirm it's in good shape.  
   The easy way is to just have the computer deal with the fuel injection. Use the distributor you've got. 
      I've seen used Mega squirts for as little as $100 but new they aren't too much more.  

These need a bunch of head work to make power. Search the term "lump porting" in a Chevy 6 context.

Read the forums at Inliners International to get some leads. Can also go to the HAMB and use the search function  - should be multiple threads on these; they tend to stay away from modern induction, but they'll know all the tricks for setting up the short block. I think you have the skillset to make a manifold and do a homebrew EFI, which would be a bunch better than the 70's technology from Clifford. If you're looking for a bigger challenge, I believe I've read articles about adapting SBC heads to these (cut one chamber off of two heads, figure out sealing and water flow, solve valvetrain geometry issues. )

Then you should put in something it doesn't belong in, like an E28, a Mustang, or a Supra.

frenchyd said:

A cam is a trade off device. Trade bottom end power to gain more at the top end.  

*VTEC has entered the chat*

Sorry, couldn't resist. Carry on!

Please put this into a lowered 2wd manual XJ. 

Uncle David (Forum Supporter) said:

These need a bunch of head work to make power. Search the term "lump porting" in a Chevy 6 context.

Read the forums at Inliners International to get some leads. Can also go to the HAMB and use the search function  - should be multiple threads on these; they tend to stay away from modern induction, but they'll know all the tricks for setting up the short block. I think you have the skillset to make a manifold and do a homebrew EFI, which would be a bunch better than the 70's technology from Clifford. If you're looking for a bigger challenge, I believe I've read articles about adapting SBC heads to these (cut one chamber off of two heads, figure out sealing and water flow, solve valvetrain geometry issues. )

Then you should put in something it doesn't belong in, like an E28, a Mustang, or a Supra.

     We haven't really asked what the intended use is.  Racing? Economical driving? Street Daily driving? 
  Or what it's going in.  Something heavy? Light? Big? Little?  
  Nor why?  
    My problem is that while I can imagine what I'd do I'm sure that's different than others. 

Captdownshift (Forum Supporter) said:

Please put this into a lowered 2wd manual XJ. 

That's a gooood troll level swap. Turbo 250 would make for a lot of fun in a 3000lbs wagon.

Don't most inline sixes have 7 mains?

In reply to ProDarwin :

Usually. 

The "bearings are for chumps" thought process belongs to primitive British engines.

In reply to ShawnG :

I saw you had posted I was thinking about Igor and found this picture at inlinesix.com

It's called Igor because of a threaded rod that runs side to side in the block. It's run high 7.98 at 167+ in the 1/4 mile so I guess it makes some power.

ShawnG said:

In reply to ProDarwin :

Usually. 

The "bearings are for chumps" thought process belongs to primitive British engines.

And the Slant Six Dodges, right?

Earliest small Fords had 5 mains, the 144-200ci blocks, but only through '65 or '66 I think.

ProDarwin said:

Don't most inline sixes have 7 mains?

 

The stove bolt six (this engine's predecessor) started out with 3, then went to four. The Chrysler slant six has 4. So yeah, while 7 may be common for more modern engines, at the time this engine came out (early 60s) it definitely was not. 

In reply to Rons :

I remember Igor. That engine ran in a Cavalier body I think.

I've never actually opened the bottom end of a slant six and the Stovebolt was designed in the late 20s so...

Ah, I just assumed because I had only really seen the guts on other inline 6s that do have 7 mains.  RB, JZ, toyota "M" engine, BMW, etc. 

And I distinctly remember reading one of the reasons the RB was preferred for big power over the VG (V6) is because it had more 7 mains vs the 4 found in the V6.  (Even though the VG will also make ridiculous amounts of power)

Mr_Asa said:

ShawnG said:

In reply to ProDarwin :

Usually. 

The "bearings are for chumps" thought process belongs to primitive British engines.

And the Slant Six Dodges, right?

Earliest small Fords had 5 mains, the 144-200ci blocks, but only through '65 or '66 I think.

Heh, we were typing the same thing 3 minutes apart.

I think the early Ford sixes had 4 mains, one at each end and two between the 3 sets of 2 rods (like the slant six)

The slant 6 did only have 4, but they're the size of the mains on the 426 Hemi, so there is that. 

ShawnG said:

In reply to ProDarwin :

Usually. 

The "bearings are for chumps" thought process belongs to primitive British engines.

Like a designed during WW2 while on fire watch 6 cylinder Jaguar? Nope,  it has 7 big main bearings. 

To narrow down what I'm thinking for this engine...I want to do naturally aspirated.  I have zero experience with turbos and I'm concerned about the packaging, with the intake and exhaust being already on the driver's side.  I've heard it can be tight getting a turbo packaged even in a Chevy II, and I'm thinking something possibly smaller than that.

Also probably not interested in fuel injection.

The "lump porting" thing is something I'm not familiar with.  

Not looking for anything too crazy, my baseline thinking is I can get 100 HP out of a 2 liter inline Volvo pushrod engine with basically stock parts, so this engine being twice the displacement should be pretty simple to get 200 HP out of, cheaply and reliably.  

In reply to frenchyd :

I knew you would chime in.

That jag 6 is hardly primitive, you knew what I meant but couldn't resist. 

At 200 HP it will be reliable.  Getting 200 HP from it will not be cheap.  It will make a really great noise.

12bolt.com is already referenced in the thread.  You might want to pick up a copy of this...

Chevrolet Inline Six-Cylinder Power Manual: Santucci, Leo: 9781931128155: Amazon.com: Books