Inliners International Forums General Discussion Engines Final Project Decision

Well after much research and deliberation, ive finall decided on my engine project...
A twincharged 250 inline chevy. Im goign to use an Eaton M90 supercharger approx 10lbs boost and a turbonetic turbo at approx 7lbs boost both blowing through a single air-to-air intercooler blowing into the top of a single holley/demon 4 barrel. Im going to cast my own supercharger manifold out of aluminum which will be placed on the passenger side of the engine and the turbo will of course be put on the driver side. the turbo manifold might initially be a set of clifford headers with a y-adapter since i already have the headers. i will have a rising rate fuel regulator, electric fuel pump, msd boost controlled 6A ignition box, HEI, o-ringed head, and a towing cam. should be fun once i get it all together.

Hi I am turbo charging a 292 for my lobsterboat here in Maine. I have all of plumbing done, I am not sure about carburation, I have a rochester 1 bbl, can get bigger jets, but can it handle boost pressure? I will start with 8 lbs of boost and go from there, what carb did you end using? You really seem to know what you are doing here! I am using a garett turbo from a 80's saab. In addition my engine will be under constant boost being a marine application it is like driving up hill all day. How do you think this affect my set up? I also found a great site dawesdevices.com they have a great inexpensive way to monitior your fuel air ratio, check it out. I am not ver computer savy and proberly won't be able to read your response, if you can e mail me hodgdonbrett@yahoo.com that would be swell! Thanks.

Well I've thought about a project like that to be honest.

I've only seen compound induction (twincharged) performed a few times before. And both times the engine was being controlled by powerful and expensive motec engine management systems. You have taken on a large and complex project I would say. But not impossible. And definetely unuqie if you make it work.

If you are going to cast your own intake manifold cosider adding bosses so in case you need to go EFI the metal is there to add the injectors. I suspect that a rising rate fuel pressure controller may not be enough and that you will have "holes" in the fuel curve.

What is the rising rate regulator used for if you're using a carb? I thought those were only useful when you were running EFI. I figured you just overwhelm the carb floats and then you're not really metering fuel anymore.

I'm guessing the rising rate regulator is for keeping a constant 3 lbs or so of pressure to the needle so the carb still gets gas when the whole works is under 10 lbs of boost. You don't want your bowl to run dry under boost.

well, as far as the carb im going to use i havent completely decided but id like to try a few; ill start off wih a two barrel with the choke tower cut off for some extra cfm, then after seein ghow that works graduate to a properl sized double pumper four barrel.
as far as the risng rate fuel pump...you have to use it because if you use a pump that only gives a constant pressure, when boost pressure rises above the fuel pump pressure youll start to lean out and i would imagine run out of fuel and have detonation. basic supply and demand concept.
as far as bosses on the intake for fuel injection...id rather use any bosses for nitrous!!!

Oh I see how it works..........yeah sounds like you'd definetely want that feature or you would overwhelm the pump pretty fast.