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#92499 - 09/14/17 07:21 PM On a budget, Turbo or EFI first for stock GM 250?
Rjonah Offline
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Registered: 09/06/17
Posts: 4
Loc: Nevada
Hello to All,

I am jumping in with both feet into the inline world. This is my first post so bare with me.

Just picked up a 73 Maverick 250ci, 61 Ranchero 177ci (have a 200 for it when the 177 dies) and a 77 Camaro 250ci. The first car I wish to get started on and the first thing I did was buy a low mile 292 engine for the Camaro so, at a minimum, I can replace the integrated intake head. It's a high milage engine so I will probably pick up a 250 short block to rebuild for the present engine's replacement.

This is a simple question, that I realize does not have a simple answer but here goes...

I have a limited budget and am looking to your knowledge and experience, having gone through this already. If given a choice of implementing one or the other, would you add EFI or turbocharge? With you your suggestions, could you include what you did and why and maybe include what you used to accomplish that part of your project? For arguments sake, let's say that I will keep the lower compression ratio so if I choose the EFI first, I can add the turbo later. These will all be daily drivers, none will see strip time, but want some seriously peppy street light to street light fun, driving mountain roads, and some freeway driving. Want to keep the engine mostly stock (not talking about the power adders) but not adverse to hardening some of the internals. Some head work, mild cam.

I have never built an engine with EFI or turbochargers but have worked on engines with both.

I live above 5000 ft and it's very cold in the winter and very hot in the summer.

I apologize for my neophyte opening question and remarks. I hope I'll have some better stuff as my projects progress...

Oh yeah, anyone ever put a 292 inline into a gen 2 Camaro. I have yet to find any good info out there regarding that swap...

Thanks
RJ


Edited by Rjonah (09/14/17 07:27 PM)

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#92501 - 09/14/17 09:36 PM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
efi-diy Online   content
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Another option for the Camaro is to swap in a late model (2002-2009)4200 vortec inline 6 out of a trailblazer. The are EFI from the factory. If you use the 4l60 trans that came with them, its a lot easier than adapting other trans.

They are either 275 or 290 HP from the factory. Add a turbo with 8 psi.. = 400hp...

The Camaro has lots of room width and length wise for the engine - might close height wise but people have put the 4200 into a 3rd gen camaro which has less hood height.

There are a bunch of inliners near Reno that have swapped the in the engine.


Edited by efi-diy (09/14/17 09:37 PM)
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#92502 - 09/15/17 07:56 AM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
gbauer Offline
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Registered: 08/11/14
Posts: 805
Loc: Maryland
I doubt the 292 will fit under your hood. I had a 250 in my 68 and looked into it. The 292 is substantially taller.

Take a measurement from the engine mount to the top of the air filter. Now measure the other engine. You'll find it's a couple inches taller. Now go get some play dough. Stick it on top of your 250's air cleaner and close the hood. When you lift the hood you'll know your clearance. It's not much.

EFI: look at FiTech. Plug and play for under a grand.

Turbo: Why not turbo charge your 250? You can get decent power out of her.

What budget are you looking at? Building an inline isn't cheap. Not at all, in fact.

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#92503 - 09/15/17 12:03 PM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
panic Offline
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Registered: 01/11/05
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The deck heights are quite different between the smaller 194, 215, 230, 250 engines and the 292 to allow for the longer stroke and connecting rods, about 1-3/4".
The air cleaner can be worked around. A "hat" similar in construction to those used on blow-through carburetors is much lower than the conventional air cleaner and allows mounting a large AC remotely with a duct.
Your next thought will be "can I use the 292 crank in the 250 motor?" Possible, not a good idea, Google it.
Deck height + rod length is why Chrysler tilted the Slant 6 (225 is 4.125" stroke, 6.69" rod) to the right 30. Mercedes did the same thing with the 300SL engine 60 years ago.

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#92507 - 09/16/17 01:52 AM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
Rjonah Offline
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Registered: 09/06/17
Posts: 4
Loc: Nevada
I am going to lump my reply to all the responses together.

Re the 292, I also got a spare parts car with 2 hoods one has plenty of room, my concern is more oil pan clearance and what to do with the passenger side motor mount. I have a 292 engine. It was cheap and I bought it to take the head, intake and exhaust so I can nix the integrated intake on the 77. But I found out 2 things about the 292. One it is a GM Goodwrench short block and two, there is literally no cylinder wear. Which is why I thought about using it.

That being written, the Camaro is a tribute car to my grandparents. It was the last car they owned before their passing. They bought it new. It was the car I would use when I would go home on leave in the late 70s. So after a little soul searching, I really want the car to look stock so the 292 is out. They had a 250 in their car so a 250 it shall remain...but that does not preclude me from putting some go fast parts in it.

Budget is ~1K per piece of the project. Hence the question, if given choice, what would you do first and why?

The FiTech has been on my radar since it came out. I have a couple of 327 cars that could really benefit from it up in the thin air. I know it can be set up to work on the inlines.

Ahhh, the slant 6. One of my favorites. My Mom had a 66 Plymouth Valiant when I was growing up. That was one of the engines I cut my teeth on. Thing ran forever.

4.2 has been on my radar as well and there is one for sale with trans here on Craigslist...but as described above I am going to stick with the 250.

Eventually I would like to have this car be both turbo and FI but I want to choose one or the the other to start. That's why I am throwing out the question. Which did you choose and why (I know, I asked this question in an earlier paragraph).

Both have benefits and detractors on paper. I see the biggest bang for the buck from a performance perspective being turbo with a blow through carb. I see EFI being the best investment for drivability at this altitude...and of course I see both giving me a fun car to drive winter or summer, at 5000 ft or at sea level. I just dont have the money sitting around to get a second 250 engine, do the rebuild, and add both turbo and EFI. But I do have a fresh 292 short block to sell to help fund the projects.

Buy the way gang, thanks for the quick responses.

Regards,
RJ

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#92508 - 09/16/17 02:17 AM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
Rjonah Offline
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Registered: 09/06/17
Posts: 4
Loc: Nevada
One additional piece of info. I have the stock drive train that came with the car. 2.73 rear end and the Saginaw 3 speed with a 3.11 final 1st gear ratio.

I also have a Saginaw 4 speed with a 2.84 final 1st gear ratio. I don't know which rear end is in the parts car but is is a 350, auto car and would presume it would have a 308.

I intend to drop the 1st gear final ratio to 3.50 for whichever trans ends up in the car. With the 2.73 rear end I should get good highway driving and with the 3.50 1st, stoplight to stoplight performance should be good even if I have the stock engine. I know that will make for a weaker transmission but as mentioned, I don't plan on racing it and not a whole lot trying to break the tires loose.

Cheers,
RJ

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#92537 - 09/22/17 02:10 PM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
TheSilverBuick Offline
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Registered: 12/22/10
Posts: 454
Loc: Ely, NV
I would get a bolt on EFI kit that have the injectors above the throttle blades, an overdrive transmission and steep rear gears, like 3.73-4.56.

My recommendation would be the MSD Atomic Throttle body ($999) with the transmission controller ($625.99). Then get a 4L60e with torque converter from a 6-cylinder vehichle (like an Astro Van), which should be about as cheap as a 4L60e gets. You won't make enough power, pre-turboing, to need anything more than a stock build. Then with some high-3 to mid-4 rear gears it's going to be a riot streetlight to streetlight and with the overdrive purr along at 75mph in the 2500-3000rpm range depending on gears and tire size.

If that isn't enough fun, the Atomic supports up to 14psi of boost, at which point you may need to upgrade a few parts in the transmisson or maybe get away with some firmer shifting in the programming.

If you re-consider the 4.2, a pair of Microsquirts ($300 each, plus $100 in wiring) will run it and the transmission.


Edited by TheSilverBuick (09/22/17 02:14 PM)
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#92631 - 10/07/17 06:34 PM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
Rjonah Offline
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Registered: 09/06/17
Posts: 4
Loc: Nevada
Well fate has determined the first part of my path. A friend has decommissioned his 292 to replace it with a V8.

So I get his ported head, Clifford 4bl intake, and stock 292 3 stud exhaust.

Good as place as any to start.

Next step is probably a Megasquirt II and a tb-220 from a GM 4.3l V6.

See you in the Ethersphere.

Thanks Again,

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#92658 - 10/12/17 01:10 PM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
efi-diy Online   content
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Registered: 11/21/04
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I'd get a TBI off of a 5.7 truck .. give you a bit more fuel capacity. TBI's don't suffer the same "too big disease" as carb's do - the fuel demand is determined from the MAP and temp sensors - not airflow through the venturi's.



Edited by efi-diy (10/12/17 04:52 PM)
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#92659 - 10/12/17 04:44 PM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
panic Offline
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Registered: 01/11/05
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As the TB size goes up, the "nervousness" of response off-idle increases. This can be cured with linkage and some planning. Read my comments: http://victorylibrary.com/Toyota/TB-linkage-c.htm

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#92666 - 10/14/17 07:06 AM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
TheSilverBuick Offline
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Registered: 12/22/10
Posts: 454
Loc: Ely, NV
I eventually removed the TBI from my Thunderbird because I never could get the linkage ratio right. It was way too touchy off throttle and the kick-down rod wasn't happy either.
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Rebuilding an OHC Pontiac 250 with EFI and a Turbo

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#92672 - 10/15/17 06:06 AM Re: On a budget, Turbo or EFI first for stock GM 250? [Re: Rjonah]
panic Offline
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Registered: 01/11/05
Posts: 1475
Loc: Hempstead, Long Island, NY
It's not the ratio, it's the geometry.

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