I have a crazy idea, but for it to work, I need to find out some ECU info.

Question 1) Do Any of the aftermarket ECU's have the ability to switch to a completely different set of injectors upon a certian manifold pressure, using seperate maps?

Question 2) What are the highest flowing injectors, and what is the maximum pressure they will reliably open? An injector that flows slightly less, but opens reliably at a noticebly higher pressure would be a benefit for this.

Question 3) what is the maximum boost that could reliably be run with 130 octane fuel, and what kind of HP would this net?

Any one know, or care what I have in mind??

 

ok 1)im not shure what your getting @ but the stock ecu pfc..all standlones swich from the primarie 550cc injectors to 850 or whatever your running....they do thei for fuel ecomoney and to get propr atomsation of the fuel ..this way you dont foul plugs @ low speeds...

2)i think the biggest are bosh 1600cc's if u need more fuel then 2 of these are runnin on a 13b..im scared of what your doin..i dont know their specs but they should be fine for any high hp car

3)holly **** 130? never seen that...just pure jet fuel eh? well all octane dose is re-tard detonation...proped tuning and fuel will never realy need 130..but figure c-16 is 116octane if i remeber right..wich with adiquite fuel is good for 1.75bar (ari's car sorry pluto i forget how much boost your runnin )

so 130 would be good for more, but the question is can the engine handle it...

my.02

 

I thought, possibly wrongly, that all the ECu's ADD on the secondaries above a certian boost level. The question is do they in fact switch over, or add on the secondaries. Guess it's time to so some checking with a 'scope.

And I kind of thought we could go with some leaner mixtures with octane that high, which would give is more power. And the fuel I have in mind <should> be redily available, and not cost $5.00 a gallon. I need to do more research. And it is very clean burning too.

 

id run bigger injectors and keep it richer...unless your talkin abt methanol...wich u pratically dont need a ic with...what kinda monster youl lookin to build?
one thing with methanol (if thats what your gonna run) be care ful it burns so clean you cant see the flame, if u ever watch f1 racing thats how come they spray the fuel flange b4 they leave the pits..i have a good vod of a pit stop gona bad...prob abt 1/4 gallon sprayed over the car and it lighted up and 25 foot radius...scarry glad everon had flame suits on...

2ndaries usally come on @ a preset rpm level, or with a boost/tps, imput..im not 100% shure, but i think its rpm under light/no load, and boost under load, but i could be wrong...

 

Actually, I considered Methanol, but I remember some time ago, a guy named Dick Guldstrand made a turbo corvette(street driven) that made I think 800 HP, he used CNG for fuel. It is clean burning, no where near as expensive as race gas, and around here redily available. I was considering a small presure vessesl large enough for a couple of minutes of full boost running. It would need no fuel pump, and just a pressure reducing regulator, and a gas solinoid valve. The high pressure lines are not all that a big a deal either, just requires EXTREME care fabricating them. Then if you need that extra bit of power, set the ecm for high boost operation, and arm the solonoid valve, and viola, maybe 500-600 HP???? Just an idea I had. I just thought that would stop lots of engine popping from knock. And it would even be clean burning, kind of environmently friendly RX-7 Just a thought. The city around here has lots of CNG powered vehicles, so it's easy to get, and still uses gasoline for regular running.
J

 

CNG has higher octane, but it doesn't equate to *that* much better knock resistance, because when you compress the mixture the heat will make the fuel vaporize - this absorbs some of the heat and prevents detonation. (changing states from liquid to gas absorbs a LOT of heat)

Problem with CNG is, it's already a gas, so it doesn't absorb the heat, so what you make up for with higher octane rating you partially lose with the fuel not soaking up some of the heat.

Bacon brought up a good point... Methanol barely needs an I/C... methanol has to run a MUCH richer A/F ratio because it has lower BTUs/fewer HCs to combine with the O2s per molecule. All that fuel vaporizing REALLY absorbs the heat!

 

Propane has a higher octane rating than Natural gas If I remember correctly. And it has a higher BPU makes more power. Diesel is the most.

your question when do the injectors stage?

my experience on a stock computer the stage either at boost or just above 1psi, and after 3500 rpm when not in boost. This relates to the stutter.

switching on the fly could be done with 2 ECU's and rpm dependant.

If you want to build a dual fuel powered vehicle I wouldn't switch on the fly, mixing may be a problem, different fuels burn at different speed this means that methanol requires way more timing advance than gas. Plus the correct mixture for alcohol are closer to 5:1 instead of 14:1

Most people whoo have cars that run on gas and alcohol have two seperate fuel systems, because alcohol eats the seals in regular fuel systems. this means, 2 tanks, 2 fuel rails, two regulators, 2 pumps, one of each being alcohol compatible.

for CNG or propane you'd have to do the same. remember Propane or CNG require richer mixtures also because they don't have as much BPU's (power per cc of fuel) you must run huge injectors, add to the fact that rotaries run huge injectors already you will probably need 4-6 1600's to provide the fuel you'll need for big power.

wow.

 

I forwarded this thread to a friend of mine that was running a propane car on the street.

With the most aftermarket ECUs the bring on the secondary injectors the same way the secondary turbo comes online on an FD. After a set point (ie .9psi) the secondaries injectors come online to assist the primaries. So, they are both on at the same time.

Bosches biggest injector that they have without having something special made (if possible) is the 1680cc/160lb injector. You can always run a few of them if you need that much fuel.

Boost pressures/power levels are irrelevant unless you can associate it to a specific setup. Different turbos make more/less power at different levels and the same goes for differently ported motors.

Best of luck to you.

 

Well my car was carbureted so the injector issue doesn't really apply. It had a 425CFM propane carb on it though if that helps any.

It did allow higher boost levels due to the higher octane of LPG but as someone already said LPG has a lower BTU so it's hard to estimate the HP levels it was putting out.

I imagine you can't really use propane with injectors because it would freeze them up. The LPG has to be 'warmed' through a heat exchanger first or it will ice up the carb. I might work if there was some sort of injector/heat exchanger combo, but I've never heard of anything like that.

I have since parted the car out because it was impossible to smog here in CA.

Mike