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My VG30ET is blown


M1chael

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That water/alcohol injection system seems pretty sweet. So you guys think that with a 9.1 to 1 block, with the turbo, a K+N or similar intake, full 3 inch exhaust, and this alcohol injection setup that I can safely run 8-10 psi? How much power do you think that would put to the wheels, about 220-230 hp and higher torque?

 

Also, I wanted to know, would it be safe to swap the injectors to the larger (but used) ones from my vg30et?

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you'll probably put out more than that. with about 8 psi (non intercooled), poorly tuned, crappy intake and exhaust i made about 210 whp and 240 or some odd wtq. you'll easily make much more than that on the setup you mentioned.

 

usually used injectors aren't a very safe bet, especially the injectors nissan uses. they tend to be pretty bad.

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You're going to need to ditch the stock computer to get over 300hp reliably, and with any remotely decent fuel mileage and tuneability. The Megasquirt info thread on this site works extremely well for the VG as most of the wiring is the same for it and the l28et. I ran megasquirt n' spark with much success on my '84 300zx turbo. I also have free access to a dyno, so it all worked out.

 

How much boost? I ran 18psi, making 390rwhp, and 440rwtq on some shitty, unresurfaced heads that were leaking coolant into the combustion chambers. I had hit 22psi in some brief dyno pulls, but the car was very hard to tune at that level because of the leaky chambers.

 

There are a handful of people running over 20psi all day long.

 

You are also going to need alot of fuel. I had shitty DSM 450cc's at 45 psi base pressure. I hit 100% duty cycle (I ran out of fuel, basically) at about 22 psi. I should have just gotten some 800cc injectors.

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  • 2 years later...
Guest dafunkmonster

The highest compression ratio you can run is dependent on how much boost you're running, the octane rating of your fuel, and the ability of the parts around your compression chambers to stay cool. Detonation is a direct result of too much heat. Compressing air increases its pressure and decreases its volume, resulting in an increase in heat. Now, this doesn't mean you couldn't theoretically be running 11:1 compression with 25psi. You could. It would just take a lot (and by a lot, i mean a metric asston) of modification. Stuff like installing oil sprayers for the bottoms of your pistons, alcohol injection, and a bunch of other tricks and tweaks that i am by no means an expert in.

 

9:1 compression with 16psi should be fine if you're using a high efficiency intercooler and 93 octane.

 

I'd suggest getting a book on turbocharger systems, something like Maximum Boost by Corky Bell. Basically, a reliable book with a graph of compression ratio vs. boost pressure (so that you don't hunt me down when you throw a rod heeding my advice :P)

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Guest dafunkmonster
To much heat and the air/fuel will ignite prematurely and put strain on the moving components.

 

Well, this is partially true. Detonation (which is what I assume you're referring to) isn't necessarily the fuel/air mixture igniting prematurely. Its really that below a certain temperature, the fuel/air mixture in the chamber will burn. It burns fast, but it still is just burning. Above a certain temperature, that fuel/air mixture becomes a bomb. It doesn't burn uniformly like it supposed to. Instead, it explodes. This creates a much higher instantaneous pressure on your engine parts than they are designed to withstand, which is bad, obviously.

 

Alcohol injection is good for two reasons:

1. it cools the charge air

2. alcohol doesn't explode very easily at all (at least, not in the pressure and temperature range that your engine will be subject to)

 

thats why you see race cars running ridiculous compression ratios without detonating, because they're burning alcohol based fuel.

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  • 1 month later...

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