Ford FE Turbo Manifolds From Burton Machine

[plovett]

Carb issues aside, I do ponder one issue with using a "junkyard 360"
The 360 has a piston way down in the hole, wouldn't raising compression artificially with forced induction make the engine super prone to detonation?

I have read, but don't know firsthand, that boost creates enough turbulence that quench is much less of an issue, compared to a naturally aspirated engine.

paulie

[jayb]

Carb issues aside, I do ponder one issue with using a "junkyard 360"
The 360 has a piston way down in the hole, wouldn't raising compression artificially with forced induction make the engine super prone to detonation?

That's actually not the way to look at forced induction.  The effects of an increase in compression are not the same as adding boost.  I have a friend who is a boosted engines specialist at Ford, and he explained it this way.  When you increase compression ratio, you squeeze a given number of air/fuel molecules into a tighter space.  When you add boost, you add more air and fuel molecules into the same space.  The effects are not the same, although I don't have a clear explanation of why.  Something about lower compression heating up the air/fuel charge less, I think...

Of course, usually with boost you also get heat, so that makes you more prone to detonation, not to mention less efficient.  Regardless, though, if you add 7.3 pounds of boost to an engine that is at an 8:1 compression ratio, you will not suddenly be as detonation prone as if the engine was a naturally aspirated 12:1 engine.  And you will make a lot more power than the 12:1 naturally aspirated engine.

Here are a few things I've learned about boosted engines based on my experience with my Vortech-supercharged FE:

- A good compression ratio for one of our engines, carbureted, with boost, is about 8.5:1

- A carburetor dedicated to a boosted application is a good investment.  CSU carbs come to mind.

- Lots of lobe separation is good.  I've used 114, and I have a set of cams for my turbo SOHC that have 116 LSA.

- Any tricks you do to help a naturally aspirated engine will also help a boosted engine.  This includes head porting, lots of lift and duration, a good exhaust, etc.  Compression ratio too, but with a carb, FE combustion chambers, etc., going much more than 8.5:1 is questionable.

- Intercoolers add power and decrease the tendencies towards detonation; they are a good investment if you can fit them in your package.

- Boosted engines like to run rich; shoot for an A/F ratio of 11.5:1 or so, at least a full point lower than a naturally aspirated engine.

[cammerfe]

 The addition of methanol to the equation as a chemical intercooler makes things much easier, in my experience.  And the 'demand' aspect of the turbos also eases things.  FWIW, I'd also skip right past the carburetor approach and go direct to EFI as well.
KS

[TomP]

I think it is a good way to wake up a truck 390 or a 360. The pistons down the hole would not be the disadvantage it is non-blown. On blown nitro engines the pistons are commonly way down the bore and the full Hemi chamber has no quench pads.

Those manifolds may not look real swoopy but the turbos are more of a restriction to exhaust flow and those won't cost any power until you get way up there in boost, with HP beyond block strength.

[FElony]

I think it is a good way to wake up a truck 390 or a 360. The pistons down the hole would not be the disadvantage it is non-blown. On blown nitro engines the pistons are commonly way down the bore and the full Hemi chamber has no quench pads.

Those manifolds may not look real swoopy but the turbos are more of a restriction to exhaust flow and those won't cost any power until you get way up there in boost, with HP beyond block strength.

OK, if you were doing a 360 with 8lbs of turbo, what would you do about rods and pistons and compression? Slow spool with one turbo, or quicker with two?

[Russ67Scode]

So to answer your question. 2 smaller turbo's will "spool up" faster that one large one.  A  centrifugal pumps need speed to make pressure in the volute unlike a positive displacement pump I.E roots blower
I think 9 to 1 comp would work given the right cam
A forged crank,H beam rods & a forged dished piston should live given you have a good block to hold it all together
Might just see this come together soon

[cammerfe]

Moderate boost (8 pounds max) should not require a dedicated rotating assembly. That much nominal boost will offer about 50% increase in power. Would you think a '300 HP' 390 would require a forged crank and pistons to get to 450 HP or would you simply improve the upper-end breathing ability?

I monkeyed with a 2300 Ford engine putting 22 pounds to it with a turbo and using a factory crank, rods and pistons. The head gasket finally gave up but the lower end looked just fine. I DID use a methanol spray on a Hobbs switch so that pump gas wasn't a problem.

KS