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Hey guys been reading on here and other forums for a long time now and decided to post up a question since this site seems to have the largest amount of experienced people on it, so here it goes. My question is concerning boost versus horsepower. Now i know that boost is a measure of restriction and im trying to stay away from having to run a shitload of boost to crutch a shitty motor, just like some people use a shitload of nitrous to make a car run a number.
Ill use my current setup that i am building and you will see why i am so interested in finding the answer to this. My current combo is an iron 6.0L lq4 block out of the box L92 heads which correct me if i am wrong but i believe they flow [email protected] intake and 280's on the exhaust @.600. It is a 408ci setup with your standard 4.00"arm crank and 6.125 rod , 9:0 to 1 compression. i have not picked a cam yet because i believe that that will be one of the most deciding factors on how well this runs. Also the car is fuel injected and will run on e85
The question is i see a lot of guys running the same turbo and same size motors and one will run 13#'s and make 1xxxhp and another will have to run 22#'s to make the same number.
Now from my understanding and I am not an expert by far but i consider myself to be fairly intelligent but the more efficient the combo is N/A the easier it will be to make more hp with less boost but in order to do that you need the standard high flowing heads and larger cam etc.But this seems to be a catch 22 sometimes because i see guys with TOO big a cam and the have trouble building boost and all that jazz.
I have done my homework on the hairdryer itself and i have a good turbo with a compressor map that fits what i want to do and i have bought the shit to make the coldside the least restricted as possible. But what i am looking for is, what is the balance that needs to be made between making the motor efficient N/A and also making that motor boost friendly? I would like to see some peoples thoughts about this as i know there are a ton of very knowledgeable people on this site and i know everyone has thier own ideas on it.
Just FYI I am trying to make around 1100rwhp with this motor
and i know these heads dont have the thickest deck in the world hence the reason for making as much hp with the least amount of boost i can without lifting heads etc.

Thanks for taking the time to read this guys,
Patrick
 

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If you are working with a particular turbo, you'll want to pay attention to the compressor map to see at what pressure level (boost) it flows the most air. If you build too much engine, you'll need to overspin the turbo to achieve the result you may be looking for. The same goes for you exhaust side, bigger heads/cams will want to run more rpm and create more exhaust volume creating the need for more turbo. This is why I often asked what heads/cam/rpm for the combo when spec'ing a turbo.

Hope that helps,
Brian
 

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You're worried about high boost lifting the heads but remember that the compression and combustion pressures are waaaay higher. Don't be afraid of a little boost pressure.

As for volumetric efficiency, your cam will be very important to maximizing what that cylinder can do with what the turbo is providing.
 
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