Conversions & Swaps LSX Engines in Non-LSX Vehicles
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Selecting an LSx engine

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Old Jul 24, 2014 | 06:28 PM
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Question Selecting an LSx engine

Suppose you want 400 rear wheel horsepower. Some LS engines will give you that right from the start, but they cost a lot to begin with. On the other hand, you can get 400 rwhp from even the LS1, but you spend a lot of money on engine upgrades.

Is it cheaper to start with a lower-end motor, like an LS1, and upgrade it to 400 rwhp, or is it cheaper to just start with a higher-end motor, like an LS3, which would require minimal upgrades to get to that goal?

(Assume that any upgrades needed or desired would be done all at once at the beginning when the base engine is obtained. In other words, it won't be upgraded bit by bit over time, but all at once at the start.)
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Old Jul 24, 2014 | 06:34 PM
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lq4 or lq9 with a cam swap will get you around 400hp for a fraction of the cost of a ls3 or ls2 you do sacrifice on the weight but makes up for having a stronger block. iron block can take more than a aluminum block
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Old Jul 24, 2014 | 06:43 PM
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Yep a LQ4 or LQ9 will be most cost effective here
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Old Jul 24, 2014 | 06:47 PM
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I too agree on going the LQ4/LQ9 route. More displacement and a simple cam change with all the appropriate bolt-ons will net you 400 rwhp all day long. If you can find a LS1, you can get 400 rwhp pretty easily too.
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Old Jul 24, 2014 | 08:48 PM
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If 400 crank hp is ok you can do it with a stock LQ9 and tune, exhaust.
http://www.hotrod.com/techarticles/e...#ixzz21ehbAsre
If you're upgrading cam etc, to get 400 to th rear, go with the cheaper LQ4.
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Old Jul 24, 2014 | 11:23 PM
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I realize I didn't give any other info, but I'm definitely going with an aluminum block. Weight is an issue. The transplant car is a Porsche 944, and weight balance is a crucial ingredient of it's handling. An aluminum-block LS engine only weighs about 70 pounds more than the stock non-turbo engine, so it'd be out of the question to go with a heavier block.

In fact, I'm going to say that weight is more important than power for what I want to do. I want more power, but not at the expense of handling, which was the main reason I got the 944 in the first place.

So with that in mind, is it cheaper to start with a cheaper aluminum block LS motor and upgrade it to 400 rwhp, or start with a more expensive motor that's almost there to begin with and then take it the rest of the way?
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Old Jul 25, 2014 | 06:22 AM
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I want to say something about putting the words "Porsche" and "cheaper" in the same thread but won't go there.

Pretty much any 6.0L or larger will get you where you want to be. All depends on what sort of deal you can find. I would steer away from LS1 motors because they are not only older, but the LS2/3 stuff is vastly improved in many ways and will hit your HP goals more easily.

As to which is "cheaper" it really depends on what sort of deal you can find. Don't forget the prices of swapping accessories if whatever you buy doesn't fit your application.

You are going to pay more for an aluminum block and the newer the motor the more expensive it will be. You might want to make a choice between cathedral and LS3 style heads, that can make a difference in how the car runs on the street. Especially if you have exhaust limitations on the car.
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Old Jul 25, 2014 | 07:15 AM
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Another consideration might be the car you are starting with. The non turbo 944s have a higher rear end ratio and might be happy with a smaller, high revving motor. An aluminum L33 can be found at less than half the cost of an LS2/3. It will only be about 350hp at the crank with cam upgrade, but as I found out, all the tq/hp isn't worth much if you overdrive the tires.
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Old Jul 26, 2014 | 01:37 AM
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Originally Posted by garys 68
Another consideration might be the car you are starting with. The non turbo 944s have a higher rear end ratio and might be happy with a smaller, high revving motor. An aluminum L33 can be found at less than half the cost of an LS2/3. It will only be about 350hp at the crank with cam upgrade, but as I found out, all the tq/hp isn't worth much if you overdrive the tires.
From the research I've done, most NA swaps also swap the transmission to one from a turbo car for this very reason. (The 944 transmission includes the rears end, as it's a rear-mounted transaxle.)
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Old Jul 26, 2014 | 04:29 AM
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Originally Posted by Pop N Wood
I want to say something about putting the words "Porsche" and "cheaper" in the same thread but won't go there.

Pretty much any 6.0L or larger will get you where you want to be. All depends on what sort of deal you can find. I would steer away from LS1 motors because they are not only older, but the LS2/3 stuff is vastly improved in many ways and will hit your HP goals more easily.

As to which is "cheaper" it really depends on what sort of deal you can find. Don't forget the prices of swapping accessories if whatever you buy doesn't fit your application.

You are going to pay more for an aluminum block and the newer the motor the more expensive it will be. You might want to make a choice between cathedral and LS3 style heads, that can make a difference in how the car runs on the street. Especially if you have exhaust limitations on the car.
Please tell me more about the heads. What is the difference between the two types you mentioned? Which is better for street use? I have no track or race plans. I want the car to be well-mannered on the street. I don't want a rough or lopey idle. At idle or light throttle, I'd like the car to be relatively inconspicuous, but if I get in it, there's no more need for secrets at that point, if you take my meaning.

Exhaust is indeed a limitation. These cars were intended for single exhaust. I'm sure dual setups exist but I've never seen a complete dual exhaust all the way back that included dual cats, dual pipes, and dual mufflers. I've seen one system that had dual 2.5" pipes, dual cats, but they fed into a single muffler. On the other hand, I've seen other 944/LSx conversions with a single 4" pipe all the way, which seems to make more sense to me than dual 2.5" (more cross section area with a single 4" than with dual 2.5"s).
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