327 + blower + MS?

[elaw]

A friend of mine has a hot rod with a Ford 327 engine. It's currently carbureted and I've been trying to convince him to Megasquirt it forever. Now he's about to pull the trigger on a supercharger setup (6-71 I think) so now I'm trying to convince him to Megasquirt it when he does that!

I figured finding an intake manifold that would work with the blower and accept fuel injectors would be a cinch. But I can't seem to find one anywhere! I'm a bit ignorant about American iron and blowers too... most of my experience is with turbocharged European cars. Am I looking for the wrong thing, or do such manifolds not exist?

Any guidance from those who've "been there and done that" is much appreciated!

[Raymond_B]

I think you'll need to inject fuel at the top of the blower instead of in the intake. Basically wet vs. dry. So it should just be a matter choice at that point, either find some throttle bodies to mount to the carb pads or something high dollar that looks like this http://www.force-efi.com/bug16.htm

[elaw]

Wow... is that really what people usually do?

It seems like a lousy solution... if you have a leak at the intake you'll be blowing flammable fuel vapor out. And you can't be sure each cylinder is getting the same amount of fuel. Or in other words you're losing most of the benefits of having EFI.

[billr]

I don't think Ford ever made a 327, only Chevy and AMC did. Ford had 289, 302, 332 (a BB), and 351. Let's start by confirming just what family this engine comes from.

[elaw]

... or what manufacturer!

I think I may have improperly assumed it was a Ford engine... I've emailed my friend to get the correct info.

[billr]

"Wow... is that really what people usually do?"

Usually, people don't use a blower like that 6-71 for automotive purposes. That kind of induction is best-suited to when absolute max power is wanted from an engine; safety, longevity, and fuel economy are way down on the priority list.

[Raymond_B]

I figured it was just some sort of weird stroker Anyway, engine manufacturer aside the fueling concept will be the same. The big blower through the hood thing is kind of an old school Pro-Street deal. Yeah you'll see serious track cars with much larger (and much different setups) , but a 6-71 can live fine on the street. Most of the 6-71, 8-71 etc have the top of the case machined for carb or throttle body mounting. The intent is to have fuel going through the blower to cool the rotors as I do not believe they are very efficient at producing boost compared to more modern setups. They do look and sound cool though

Here's a link to BDS, these guys have been doing it for a while. http://www.blowerdriveservice.com/

[billr]

That's my understanding, too; that having some fuel going through the rotors helps keep them cooler. Remember, these "x-71" blowers were not originally intended for compressing air much at all. They were for "moving" air into 2-stroke diesels, at very low delta-P through the blower.

[Raymond_B]

Bill, how did you pull off posting at 3:27

[elaw]

Usually, people don't use a blower like that 6-71 for automotive purposes. That kind of induction is best-suited to when absolute max power is wanted from an engine; safety, longevity, and fuel economy are way down on the priority list.

Well, it's not exactly a daily driver. It's basically a drag racing car, although he does drive it to & from the track.

And while I understand your point, not burning up pistons is fairly high on the priority list... especially as this engine wasn't built from the ground up for forced induction. So IMHO (and again I'll admit I have very little experience with this type of motor) even fuel distribution is very important. And there's no better way to achieve that than port injection!

[elaw]

That's my understanding, too; that having some fuel going through the rotors helps keep them cooler.

Do you really think it makes that much difference? By my calculations, an engine running at 14.7:1 AFR ingests about 8,600 times as much air by volume as it does fuel. It doesn't seem to me the fuel would have much effect.

Remember, these "x-71" blowers were not originally intended for compressing air much at all. They were for "moving" air into 2-stroke diesels, at very low delta-P through the blower.

Good point! Of course that doesn't stop people from trying.

I don't expect he'll be running much boost though... probably 4 or 5 PSI max. Considering it's a 9:1 compression motor running on pump gas, a not-very-efficient compressor, no intercooler...

[Raymond_B]

I certainly wouldn't expect you to believe a stranger on the Internet, but as you do your research you'll find the fuel is best injected in to the blower. Vehicles have run (and run well) without port fuel injection for quite a while

[elaw]

Yeah I wasn't meaning to be argumentative... this is all pretty new to me and I'm just trying to understand.

So with those setups that have a bunch of injectors mounted on a plate between the throttles and the blower intake... how are the injectors fired? I'm guessing with 8 injectors you might do two alternating banks of 4? Sequential doesn't seem to make sense, and firing all 8 at once seems kind of evil.

[billr]

Understand, I'm way out of my element with blowers, but...

I think fuel is often injected both at ports and through the blower. With the very high-hp applications where blowers are for "go", not "show", I think manifolding is seldom a compromised affair, like the typical production dual-plane. Manifolds are specialized IR types, and great effort is made to get the same flow to all cylinders. Special heads, porting, all that good stuff. This is done to keep from melting a piston due to running hotter than the others, I'm sure, but also to get the most power out of every cylinder. I expect every piston is right on the ragged-edge of melting. As said, consulting a blower expert, like BDS, is a wise choice. I'm sure aftermarket "6-71s" are far different from the original GMC design for diesels.

[Six_Shooter]

Roots type blowers use the fuel injected into them to help keep them cool. Even a little bit of fuel has quite the effect on temperature.

Most of the time mechanical injection is used that will continually dribble fuel into the blower, not on/off pulses that come with EFI. It will be all nozzles peeing at the same time as well, so "batch fire-ish". Since all fuel goes through the blower and exits at the same point, the fuel distribution is more controlled by the intake valve events than forced distribution through nozzle placement.

Typically the nozzles used with mechanical injection were not really able to be used below the blower as well, due to their design. IIRC there are some special nozzles that can be, or through the use of pressurizing the exterior of the nozzles can be installed below the blower.
What does this have to do with EFI? Not a whole lot but it adds some background on how the systems were originally set up and give some idea on what may need to be overcome with EFI.

I know some people have installed two sets of injectors, one near the intake port that promotes better idle, and in some cases better fuel distribution and then a second set above the blower to help keep it cool and add more fuel.

[Raymond_B]

Yeah I wasn't meaning to be argumentative... this is all pretty new to me and I'm just trying to understand.

So with those setups that have a bunch of injectors mounted on a plate between the throttles and the blower intake... how are the injectors fired? I'm guessing with 8 injectors you might do two alternating banks of 4? Sequential doesn't seem to make sense, and firing all 8 at once seems kind of evil.

Not taken that way at all! It's new to you and can seem weird, I understand. I'll have to find some pictures of a fellow Lightning owner than installed a big roots type blower by adapting the blower to an EFI lower manifold. He kept the EFI, but added a set of injectors above the blower that all fired every time a "lower" injector fired. Pretty crazy stuff.

Edit, found it! He's running an 8-71, but same deal.

[slow_hemi6]

Wow... is that really what people usually do?

It seems like a lousy solution... if you have a leak at the intake you'll be blowing flammable fuel vapor out. And you can't be sure each cylinder is getting the same amount of fuel. Or in other words you're losing most of the benefits of having EFI.

I use a TBI, for me the biggest benefit of having efi has always been on the fly tuning without having to break out a spanner or screwdriver or get burnt by something hot or get fuel everywhere. Anyone who did old school tuning knows what I am talking about.

[racingmini_mtl]

It's going to be hard to close that hood (bonnet) over that engine...

[Raymond_B]

It's going to be hard to close that hood (bonnet) over that engine...

For sure, he's gone through several iterations and with that motor there was a large hole cut. If you look closely you can see where the firewall/cowl was notched.

[dontz125]

"Here we see an example of Engine Forward mounting, favoured for ease of maintenance and anti-wheelie balancing. "