Thread: Brodix IK Heads.

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Originally Posted by jerry clayton

turbocharged diesel to haul it down to lower altitudes-

Jerry, can you explain why a turbocharged diesel (injected, high pressure) is going to be better than a boosted, injected gas engine?

Diesel has no throttle blades--------runs full open and injects amount of fuel to do what throttle pedal is calling for-----

Boosted, injected gas engine-we are just getting into direct injection engines-all previous to now fuel injected engines were just squirting fuel into the airstream at various points in the system-some at throttle plate, some were somewhere into the flow path usually at manifold to head area with others having more exotic angles,etc.
Any way, the power is requested by throttle opening and will vary with pressure altitudes having tremendous effect on amount of oygen in air --------

Originally Posted by jerry clayton

Any way, the power is requested by throttle opening and will vary with pressure altitudes having tremendous effect on amount of oygen in air --------

Which is why the EFI engine operates from absolute pressure, or alternatively measures mass air flow directly (both for boosted engines). Ray can get where he's wanting to be with the boosted & injected gas engine just fine, IMO.

Its been a while since I flew any supercharged airplanes--------but as I remember,on unsupercharged engines you lose an inch of pressure per thosand feet-29.92 is standard sea level number. and IIRC the normal POUNDS of pressure is 14.7?

And for a engine with a supercharger to actually produce any BOOST above normal ambient pressure it would have to be running way above a driveable speed in the mountains.

Now if you were doing one of the NEW GM direct injected engines with a blower that had a pretty high ratio drive, you might be able to tune around it a bit by severely reducing timing probably to a number that was after tdc soas not to get spark knock at the reduced rpms you would be seeing on the road ( or 145 octane avgas which I don't think has been available since mid 60s?)

Ray, like I said above, IMO you can get where you want to be with an EFI engine that includes spark management (timing). Since the Spark and Injection maps are both based on MAP (manifold absolute pressure), with values programmed from 0 to 31"HG and 0 to peak RPM, the spark and mixture will take care of themselves regardless of your throttle position, load and altitude/barometric pressure. Now I'm not going to tell you that it's gonna knock your socks off if you drive up Mount Evans or Pike's Peak, or that you'll turn the same 1/4 mile times everywhere you go, but your mixture will follow the Injection map and your timing will follow the Spark map, all accounting for the swings in barometric pressure you'll see along the way. Like Denny said, it's gonna take some of your "play money" to pull it together, but I think you can get there. Again, just my opinion, and they're like belly buttons.

Tech's giving you some good guidance, and I look forward to more dialog between you two as you work through your questions and try to optimize the approach. Should be interesting.

OK-to get away from basic differances-

You have stated that you are a carb lovin man and also that you have a Holley -

Leave the static compression RATIO where its at because with the higher alt you won't have too much actual in the cylinder pressure. Get some Holley jets down to around the upper 50s or lower 60s up to mid 70s and a gathering of power valves from 3.5 to 8.5. Does your carb have a seconary metering block or is it one of those thin cheapie plates? If its a plate purchase a seconary metering block kit(will include longer bolts) and also make sure your fuel line set up will work with the longer spacing.
For a starting point Jet the carb down about 4 jet sizes (assuming you are savvy enough(in that thin air breathing those over rich exhaust fumes) to use a consistant brand/source of gas) When you get it running with a decent drivability on the primaries( up until seconary opening point) you can then start on the power stuff with different springs in the vacume opening diaphram and the seconary jets

Then when you do go on a trip where you come down to farm level fiels, you can easily change back to jets that are 2 sizes smaller than whats in the carb as shipped (I like #70 for the 3310 carbs pri)

At least with the Holley you don't have to take off the carb and on a chev the distri isn't in the way of the primary bowl bolts.

Since the air is thin up there, use a pretty open aircleaner to let in as much as you can, choose a cam that gives the atmospere time to push in (remember the engine doesn't suck, the atmosphere equalizes the pressure ) and have as free flowing exhaust as you can stand in the car-might need to try 2 or 3 different type mufflers to get rid of drone sound effects.

And since you are at higher alt you can probably run a couple more degrees of timing if you have good fuel as your absolute cylinder pressure will be lower than when you come down out of the hills for a road trip.

And there are now some systems that you can program ignition timing for carbed engines that work real nice and you can mount them remotely( where you can reach them) in the drivr area

I think I need to back out of hi-jacking this thread and at some point start an engine build thread of my own.

I have noted that on many of the engine build questions, respondents wanted to know as much about the current combination as possible, and how the hot rod was to be used. I attempted to give real answers in how i use my rod and feel that perhaps too much information was given. Also a budget request was often desired which I did not do. As it sets, I am retired and living on SS so toy money is hard to come by. I cannot follow Techs advice and purchase heads $1100, blower $2500, Fast fuel injection $!800/$2500, snow water injection $350 and the price of a cam/lifters. Nor can I sell what I have and plug in a turbo diesel engine as noted. I also hope the suggestion to move my home was in jest. I have ran carbs all my life and am aware of their limitations in comparison but also know they will do the job I want very well. My old 40 has lived on both coasts and at 8500" here in New Mexico. Currently It is jetted 3 sizes lower than when in Baltimore/DC area and in the mid Florida area. With the current jets I have ran with the Greybeards on trips to the LA roadster show without incident. I am smart enough not to push it to the limits at sea level nor over 9000' passes on the way to Denver. Some of the Greybeards have come from Niagara Falls Canada, Florida, the Carolina's, Florida, Oklahoma, Arizona, and the south coast of Texas. I do not recall an injection on any of their cars. I do have the opinion that I can make a carb work just fine for my driving. I like to take long trips because the fun in the ride is often as good as the destination, taking a day trip up the coast like most do is of little interest to me.

I have not spent my youth driving dragsters or other race cars, I do not have the background of building super high performance engines year after year in a high dollar shop, nor do I have the experience of building hundreds of engines in my lifetime. Those are the professionals to whom my questions were directed. I want to build a better motor but feel I need to back off and perhaps come back with limited questions later. Thanks for attempting to help. Ray

Went back and read most of this concerning Scooting's deal===
I did not intend for anyone to think that I meant for him to put a turbo diesel in the car- I meant haul (trailer queen ) it down with a turbo diesel truck and then drive it at the lower altitudes.

At higher altitudes with the thinner air you need to get more into the cylinder-----that means bigger carb, higher flowing heads/manifold and a carb that has been optimized to get the fuel into the airstream-----now you need to have cam timing that is shorter to stop reversion but with more lift so that when valves are open the mixture flows at the best rate for the absolute pressure available . You need the most open exhaust that you ( or the law ) can stand the noise from- lots of split in the overlap so exhaust gets out of the cylinder before intake opens and then open intake at highest rate toward the best flow numbers. Dist needs to be curved and vacume advance doctored for more control ( those old Ford dual diaphram dist work good)

There is a modern type control ( think Edelbrock sold it for there carb manifold on LS type engines?) where you can program the spark even remotely to drivers position ( left side dash?)

If you are building an engine from scratch for high altitude use consider the rod length ratio to stroke for more optimun piston speed at the top and bottom dc.