Stovebolt.com Forums The Shop Area The HiPo Shop 6 Cyl Fuel Injection

Been thinking about all the stuff you can do to warm up a six cylinder. Does anybody know how the FI systems work on later model Chevy cars and trucks? The injectors . . . are they just solenoid valves that open when you hit them with 12Volts? Are they digital (on/off)and fuel delivery is a function of duration or are they analog (low voltage = low flow / High voltage = high flow and fuel delivery is a function of voltage)

I have a couple of surplus DSP controllers laying around and have been thinking about putting together an engine management system. What about crank / cam position sensors? Or should I put something on the distributor shaft? Just thinking out loud.

Also, while I am at it, is there any advantage to phasing the cam while running? Wish these old sixes had a separate intake and exhaust cam so you could phase them separately.

Anyway, just wondering if any of you guys have some input here. I have gone through the calcs on timing and it wouldn't be that tough to fire injectors as a function of shaft position and be able to tweak timing and duration on the fly.

Clifford research (the 6=8 people) has a fuel injection for the Chevy six in their catalog.

Ken, I know that GM throttle body injectors pulse on and off. To deliver more fuel, the pulse on rate is increased.Obivously, the the vehicle's computer controls the rate through feed back from the various sensors.I'm pretty sure that sequential port injectors work on the same principle.The port injectors are not timed to the individual cylinders like the older mechanical fuel injection or Diesel injection.They just spray in order in a constant cycle. Holley makes programable throttle body injection systems with an ECM and sensors.I think to get the system up and running properly, you would need dynometer time to map out fuel curves for street use.Adapting a GM throttle body is tough since, the stock system has limited adjustment.Maybe if the engine you want to use the system on is a similar capacity and tuning to a known GM engine ,you may be able to adapt it. Like using a 4.3 complete system on a 261 engine etc.The hardest part would be setting up a speedometer speed sensor on an older vehicle.I bet some one out there has done it.But would it work better than well sorted carburation, considering the time and money spent.

[ 12-06-2001: Message edited by: Tony ]

I don't know much about this, but why can't you take a system from a engine of the same size and adapt? It seems to me the injectors or computor wouldn't know the difference. The mechanical part of adapting shouldn't be to hard. The timing could run off of the crank, I have seen 5HP B&S with crank trigger timing. The rest of the sensors could be mount easy enough. Its going to take somebody with a understanding of the computor to make it work. Just think how cool it would be! New hood emblems
" 261 L6 FI " !!! Joe

This may help
http://www.fuelinjection.com/

[ 12-07-2001: Message edited by: chuckthetruck ]

Might try SDSEFI.com some of the F**d guys have been using it on OZ engines. The advantage is that you can make adjustments on the fly and don't have to have a laptop to do it. Also it is relatively inexpensive compared to some of the other stuff.
Dennis
I was OK but I got over it.

Dabond . . . great site! These guys seem to have a much better approach than what I have seen on other sites. An injection system on a 292 with a T-bird supercharger . . . hmmmmmm

Ken,
The only problem I see with the GM 6's is the siamesed intake port. That could probably be overcome with a port divider. F**d made it easier with their 300 6. As a side note my neightbor came into a treasure trove of Crosley motors. We were looking at them today and although they have siamesed ports, they could be port divided, and the head/cylinders are in one casting. If we could come up with some injector nozzles small enough ( only 45 CI) and turbocharge one of these ( 7 to 1 stock compression) we thought about building a belly tank or something and going to Bonneville. Probably a pipe dream but WTH it's fun.
Dennis
I was OK but I got over it.

I have read about folks who have put dividers in the runners leading up to the port. Or I guess you could do 3 injectors and just run them with the pair of signals associated with the two runners. If the controller doesn't like it, all you would have to do is put a flyback diode in each of the signal wires and it would never be the wiser.

Ken
From what I,ve read you want to point the injector at the intake valve. If you put port dividers in that wouldn't be a problem, but you would have extend the dividers out of the port enough to get past the injectors. The port injection injection isn't exactly a precise injection like a diesel. Therefore you almost have to have the ports divided to keep the mixture right.
From what I've read and experienced on these things it gets worse if you have much overlap in the cam. Probably the best bet on the Chevys is to use a throttle body setup, but then you get back into the management problem. Well everyone said Stovebolts were easy.
Dennis

I have a great appreciation for old stovebolts in old trucks, but I also have in mind to have an in-line hotrod with a little more high-tech outlook. I guess I was thinking the port injectors would be easier to deal with if using an Eaton super charger. I would rather pressurize air than pressurize air/fuel mix in a home-made plenum / intake manifold. I'll keep turning it over in my head and picking up parts and pieces . . . someday I'll figure out a good clean solution that will get 250 - 300 reliable horses out of a 292.

Ken,
You might want to look at Hot Rod Magazine from a few months ago. This guy had a 292" 6 with a draw through turbo and was running 10.7 sec 1/4's. He had a variable boost guage inside. The mag people said it drove like a semi stocker on the street, and he did drive it to the drag strip, but just turned up the boost to run. BTW it was a 37 Chevy coupe with a home built frame and a Olds rear end. IIRC it was running a T04 turbo drawing through a quadrajet. Just something to think about.
Dennis

Yeah that turbo supercharging is a good suggestion. The intake and exhaust are on the same side making the plumbing easier.No extra drive belts making a long engine longer. Perhaps the parts of a Buick Grand National will adapt.Those Buicks made large HP.I think a non supercharged 292 can give yield 250 hp, on the street with out becoming too lumpy.That story on the turbo 292 is interesting.A famous east coast drag racer has been running 292's for years, sometimes turbo charged.His cars are dedicated dragracers .He has a hard times getting those low ET's. Maybe he is a lousy racer or some one else is stretching the truth.

Holley has one for the 292. Anybody looked at it to see how it handles the ports, etc.?

Hey Tony, I had a black 84 Buick T-type that was 90% GN parts, but then my mom got an 87 GN that was significantly faster. SFI 3.8l with turbo and intercooler . . . 300+ hp out of a 231? cubic inch. She just sold it last year with 140,000 miles on it and it still ran great. The GNX's were the really fast ones though.

So you think a turbo would be a better way to go huh? Always thought a blower would be cool.

Dennis, I'll see how the Holley one looks on the web if I can find it.

I built a turbo 250 nearly 15 years ago for my son's early Nova, and it is still in use. It was pretty simple except for my choice of carbs.

I used the early Buick V6 turbos that were draw through. They were only about $300 new in the box at that time. The Original Buick manifold for this unit had a three bolt flange connected to the turbo. I built a small adapter and used the original 6 manifold. Once the turbo was bolted to the manifold, a 180 degree u-bend pipe was used to get from the exhaust manifold outlet to the turbo inlet, and another nearly 90 degree piece got us out of the turbo and headed back under the car.
Oil was supplied from the pressure sender location, run through a remote filter mounted on the firewall. The idea behind the remote filter was to help insure cool, clean oil. We just punched a hole in the pan an brazed in a fitting for the drainback.
The original turbo 3.8 had two intakes that bolted to the intake side of the compressor. One was for a 2 barrel, one used a q-jet. I choose to use a sidedraft Solex that had the same size throttle blade as the compressor intake. A small adapter took care of the hookup. After making my own needles out of brazing rod, I got the right taper to get enough enrichment when under full boost. The built-in wastegate limited boost to 7.5 lbs. Water injection was added later because my son didn't want to buy premium fuel. I put a Hobbs switch in the intake manifold set to switch at 4 lbs. Ran the power to a windshield washer unit I took off a small pickup. Putting a small brass needle valve in the waterline helped adjust the amount of water blown into the engine. I picked up the brass needle valve unit at the petstore. It was entended for use at regulating the amount of air going into small fish tanks.

All in all, the amount of time spent to turbo the engine was about a day, with another day or two wasted on sorting out the carb. If I had it to do again, I'd find the original carb to turbo intake system. It would have saved a bit of headache, although that carb is still on there without having created any problems.

Greybeard, did you inject water after the turbo? I have heard of people trying in front of the compressor to get good atomization but ran into problems with it eroding the compressor blades.

Ken,

I injected the water in front of the carb. I built a small nozzle into the airfilter housing that was bent 90 degrees and sprayed through the carb directly at the compressor blades. I've not had it apart in all these years, so I'm unaware of any problem with what I did.

If that was a problem, one could avoid it by using a pressure capable water bottle[like a surge tank], and run a line from the intake[power brake tap] to the top of the bottle to help reduce the pressure the pump would need to produce to overcome from manifold pressure. The pressure line for the pump would come off the bottom of the tank to wherever you wanted to introduce the water. I believe there are aftermarket washer pumps. I've seen surge tanks with top and bottom outlets and sight hoses on the sides in Streetrodder outlets.

I purchased a Holley Pro Injection Unit at
an auction. It is a one barrel throttle body
type. It's supposed to work with 250/292 Chevy, 300 F***, 258 Jeep inline sixes.
Don't know as it will improve horsepower
any, but may be a little more responsive than
carb is, maybe better fuel economy.
I need to make an adapter for it. It came
with adapter for Jeep engine.

Hey Ken,

A couple of years ago, Accel had a system with seperate injectors, an adapter you could weld into any intake manifold to mount the injectors, a 90 degree adapter from a standard carb mount into a TPI throttle body. I'm sure they had computers and wiring harnesses as well.

If you're set on building your own (very cool idea, BTW) you might start with one of those kits and modify the 90 degree adapter (or just build your own) so that it was more of a plenum with more volume.

I was always going to take an old head and put it in the chop saw and cut it in half through the intake port, just to see if the water jacket is close. If not, why couldn't you drill holes in the head UNDER the valve cover for the injectors? If you drilled them at an angle, you could have the injector shoot right down on the valve. Some sort of fuel rail could be make to supply the injectors. Imagine the dumfounded looks when you popped the hood and the only thing on the intake manifold was a throttle butterfly and a MAF sensor

I just got back from a technical school on John Deere High Pressure Common Rail fuel systems. This system is absolutely AMAZING, both in diagnostic abilities and horsepower output. This will require a lot of thought to adapt this technology to a Stovebolt, but I think it could be done.

Racecarl,,,,,you have my ears perked!!!!
This sounds interesting!

OK Racecarl . . . get you camera and chop saw warmed up and lets start a new thread!

This photo is looking at the center intake ports on the 292 I just got. See the two small dimples ontop of the port on each side?Looks like you could drill down for an injector. The two end ports are about the same. If the injector nozzle is 3/8 of an inch or so it could work [img]http://pstr-m05.ygpweb.aol.com/data/00B/7B/E2/D8/9B/NV+aPPSimycmKb4SXcJyIPB6dxfTKzxZ0180.jpg[/img]

I've got a couple of link's you might want to look at. http://www.turbobuick.com/messagebd/
http://www.gnttype.org/techarea/techpage.html http://www.diy-efi.org/ http://www.electromotive-inc.com/ http://www.customefis.com/

Hopefully, with all of those maybe you can come up with something. The dyi-efi site can be a little flakey to get to, but it is the most technical. In other words, written for/by engineers, which is what you want.

[ 12-16-2001: Message edited by: Stovebolt Staff ]

Uhhhhh . . . Vaughn, I think there is something funky about the Motorhood link. Other than that one, these are among the best I have seen.

Peggy took care of it, Ken -- Thanks for the vigilance. It was fun cruising to the Turbo Buick site -- When those Grand Nationals came out, I wanted one so bad. A buddy of mine bought one and took me cruising the night he got it. Then he parked in downtown in DC and it was gone. He got it back a month later -- well, just the frame and the body... Had less than a 1,000 miles on it, too.

Take a look at the picture Tony posted.

In the center of the intake port is part of the head casting that the head bolt goes through. It is basically round, it does not separate the two intake valves behind it. A trick to improve intake flow a great deal, is to mill the casting out of the port. A stud is used instead of the original bolt, with the stud protruding into the port only by enough to install a nut. The flow over the nut does not disturb intake flow nearly as much as the casting did. The hole left above the port where the bolt went through is closed off using a plug.

This should improve the power of an injected engine as well.

Tony, I may try to get pics of, here we have 250 with multiport efi. But with a whole different head. Separeted runners on all cilinders, they do not merge after the bolt.
Greybeard, this procedure helps in high rpm, hurts a lot the low end grunt. And we can have for sure that to keep it going must run a li'l rich in lower rpms, so fuel consuption suffers a lot.
For a long time the tunners here used to do it, remove the center of the port, but it's results are not clear, some like, some dislike, but listening to the results of a 12 port wayne on a stovebolt, I'd say that I'd rather have a full divider in a head port than running an engine with a common runner for 2 cilinders.
Just my 0.02.

Wow! you guys are too technical for me! Back until 99 models in truck plant here, we made Mexican sixes and trucks that were mostly the same as the old 250's. They had a fuel injection body in place of carb on them the last few years. don't know if you can go to Chevy dealer and get #'s of parts or not. Maybe the last poster is talking about this engine as it was made in Brazil I believe. It's just a stock set-up, not racer, but may be better than a carbed one.

GLPerry, we have 250EFI here in Brazil for a long long time. But it's a multipoint set up, distributorless system, the intake manifold is a big piece, crossover the engine and the throttle body is on the pass side. Works very smooth, but is not all that powerfull, just 168HP, and has a flat cam, the engine is not just a regular 250 with the efi, is a new set up, longer rods, a new head, etc... out of a running vehicle worths almost nothing, since gas here is a li'l expensive. Some kiddos are swapping them on earlier L6 cars and trucks, but performance is not all that great, still a gas guzzler, just has a terrific look. I've been lloking at an engine like this for a while, and I think that if properly tuned (requires a new intake made to fit the different port arrangment in the new head) and a cam with more LDA would make for a good torque and low fuel consuption package.

Alerandre, How much does gas cost in Brazil in US dollars?Do you use a lot of alcohol fuel down there?

Gasoline, three types available; prices ranging from US$ 0,73 to US$ 0,86 per litre.
Two regulars, one high octane, but nothing really special.
Alcohol is much cheaper, around 40 cents per litre.
In our biggest cities(Rio de Janeiro, São Paulo and Belo Horizonte, among others) we can also find CNG/LPG fuels also, and they are cheaper. But the conversion is expensive, and the performance is not all that nice if you tune the car for milleage rather than performance.
I also remember that in the eighties a Governor of a State in the U.S.(that I cannot remeber what state was) invited some guys from Brazil and even took a Brazilian alcohol powered car (a Chevy Opala, 151CID powered) to a parade, but I never knew what happened after.
Many people consider me insane when they see the type of cars that I ride. And when they realize that my Ram is a real 10 cilinder, they just disbelieve.