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Car People... Twin Turbo 390 FE?

ISAslot

ISAslot

Platinum Member
I've been thinking about dropping a 460 in my car, but I don't really want worse gas mileage than I already have.

The Grandnational and other cars with turbo don't seem to get much worse gas mileage than they would w/o the turbo; when not getting on the gas, or after turning down the boost.
It would also be unique. My car is already pretty rare, and this would make it more so.
I have heard that you can get more low end torque with a SC, but I'd rather have more high end power with the turbos, just because the 390 has quite a bit of torque already.

So is this a good idea? Would it work (can I find the right turbos, etc.)?

*also, I'll be doing this quite sometime in the future*
 
First of all what kind of car is it? What version of the 390 do you have? The biggest problem is that almost all versions of the 390 have too high a compression ratio to support turbocharging without running very expensive racing fuels. You would either need to find large chamber (low compression) heads to lower your compression. If that is not an option then you would need to rebuild the engine using custom low compression pistons. These mods would only be necessary if you can't get 8~9 to 1 compression easily. I have only had a couple of 390s and both had almost 10 to 1 compression so I am not familiar with what possible stock ratios there are.

The biggest nightmare will be the exhaust tubing/routing. It is not impossible but it will be a lot of work. My biggest concern would be heat. These old FE motors aren't the coolest running creatures and after stuffing the engine bay with toms of heat emitting hardware you might have a tough time keeping the ar from overheating. Once again, not impossible to overcome but defiitely a consideration.

good luck
 
390 is a domestic engine, no? I'd get a centrifugal SC like vortech or Paxton. pretty much like a turbo, but without the pains of designing/fabricating headers. also, does this engine use EFI? i don't know much about domestics, but can you use turbos with carbs?
 
Thanks for your input Ronstang. 🙂

The car is a 68 Ford XL-GT fastback, and the 390 is the Z code 315hp, 427 ft/lbs (gross).

Right now the compression ratio is 10.5:1, but I would likely get some aluminum heads. If I got the edelbrock heads, I pretty sure that would lower my compression ratio down to 8.0:1 - 9.0:1 neighborhood.

I would be starting with a fresh motor, I'll either rebuild the one I have, or get another block, so that I can run the car and build the motor at the same time.

As for heat, I guess I could go with some sort of electric fan set up.

Would this setup, with the turbos, be a good mix? (They provide this chart.) Or would a combination of parts from other companies be better?
 


<< 390 is a domestic engine, no? I'd get a centrifugal SC like vortech or Paxton. pretty much like a turbo, but without the pains of designing/fabricating headers. >>



I've thought about SC's but I just think turbos would be cooler. 😎



<< also, does this engine use EFI? >>



Holley carb, but if I must switch to injection I guess I will.



<< i don't know much about domestics, but can you use turbos with carbs? >>



Thanks for bringing that up Jamestl, that's another one of my questions. 🙂

edit: spelling
 
It's real hard for me to sit here and &quot;bench race&quot; a combo. I would have to look into a lot of parts and possible combos to be able to make a good suggestion. If you go with Edelbrock heads you would definitely want the 427 versions with the 76cc chambers, that is if they have the proper exhaust bolt pattern for your manifolds. Remember that FE motors used several different exhaust bolt patterns. The 427 version heads are only drilled for the vertical pattern.

You might also look into O-ringing the heads to prevent the head gaskets from blowing since Ford engines are usually a little scant on the number of head bolts. There atre several options here ranging from full O-Ringing to the use of Fel-Pro Loc-wire head gaskets (of which I don't know if they are available for FEs).

Your biggest hurdle will be fuel management. If you are going to use a carburetor then be prepared for a tuning nightmare. In fact you might never get it right. You could very easily blow your brand new engine up in a very short time. Fuel injection is the way to go but this opens up a whole other can of worms and a bunch of money to purchase a stand alone system.
 
I'm not a big Ford guy but I can tell you one thing. If you have 10.5:1 compresion then a set of edelbrock heads is no way going to bring down your compression to 8 or 9:1 especially if they have a 76cc chamber. You would need about a .500 head gasket to get it to drop that low and I have never heard of gaskets that big. I just bought some edelbrock heads and my combustion chamber actually got smaller. Stock heads were about 81cc and edelbrocks are 75cc.

Turbos work with carbs, you can either get a blow thru (carb is encased in a box between the manifold and piping) or a draw thru where the carb sit on top of the turbo.
 
Ronstang

Wow, learning some things I did not know about the 390. Maybe that is why I don't see as much high performance parts for it as I do with other engines.

I looked into headers awhile back, and the only ones for my application (that I could find) were Hooker headers and they were around $350. Seemed kind of high compared to other headers, for other vehicles.

Concerning the fuel, I'd really like to keep a carb set up, because I'm beginning to get really expensive already with the heads/turbos. 😛
I don't know if this is standard for tweaking carbs, but this Holley expert has a page set up detailing the adjustment of carburetor fuel/air mixture. He recomends the installation of a oxygen sensor in the exhaust pipe (have a bung welded in for it), and this will tell how good the mixture is at certain RPM's and therefore certain carb fuel circuits. There are meters that can be attached to the sensor, ones that have gauges or LEDs, but if someone was really cheap they could just use a multi-meter.

Now if I added the turbos, would carburetor adjustments almost need to be dynamic? For example, if I had the boost really low, I'd need certain settings, then if I increased the boost, I'd need different settings for all the circuits?


Stallion

I've never heard of the draw thru turbos. Is the turbo directly on the intake, then the carb is on top, or is the carb/turbo combo connected via a duct or plenum?
 
Well I can help you with the headers real quik. Ford Powertrain Applications will have them. I have a 67 galaxie 390 and used their headers and they fit perfect and sofar after 3 years they still look good. http://www.critesrestoration.com/ also has some.

FE big block forum

love fords

They have a realy great, busy, and free mailing list and will have somebody that can awnser your questions.


I am also on a real good galaxie mailing list but I just deleted all my e-mail and haven't recieved a new one yet so I can't remember the address to sign up 🙂. I ll post it as soon as I get a new e-mail.




Galaxie Club you have to join to get on their mailing list but they do have a lot of good links you can get to without joining.
 
Thanks a lot for the links thedarkwolf!

I was worried that the Hooker headers would have no coating if I bought them; they don't have a picture up, or didn't when I looked, and they didn't specify. At least these look like they'll hold up much better, thanks again for sending the info my way. 🙂

 
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