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Old 08-30-2007, 03:56 AM   #1
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Default 60 trim worth it?

If I'm not building the motor, is there much benefit of the 60 trim over a standard Saab t3 which I think is a 50 trim? I know the 60 will flow more, but I would blow my engine before I would come close to maxing it out, probably wouldn't even max out a 50 trim on the stock motor.

please give your input.
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Old 08-30-2007, 09:50 AM   #2
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the 50 trim is only able to output around 245BHP.

the 60 trim, 320BHP


Since this is not greddy related...lets keep it in the DIY section....
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Old 08-30-2007, 11:24 AM   #3
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50-trim


60-trim


I use 10hp per lb/min as a general rule. It's not unheard of for people to get max airflow out of the turbo, in the case of the 50-trim that'd be around 275hp, and around 320 for the 60-trim. Of course to hit that you're running really high boost, a big IC and probably 116 octane leaded fuel. What you need to do is figure out what boost you plan to run. Lets say 12psi. At sea level on a perfect day that'd be around a 1.8 Pressure Ratio. On the 50-trim you're realistically looking at a max of 200hp. On the 60-trim it's more like 250hp. In the 7psi range (1.5ish Pressure Ratio) the 50-trim is going to put you at around 160hp or less but you might make 190ish on the 60.

It's not an exact science by any means.
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Old 08-30-2007, 11:31 AM   #4
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Both can be maxed with stock motor, given proper tunning. 50 will spool quicker and have less topend 60 will just be alot more fun. Wichever it is still 1 million % better than stock.
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Old 08-30-2007, 12:23 PM   #5
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the difference in the roating mass on the wheel between the two is trival, so the size of the wheel will not effect the spool, both will spool the exacty same; one will simply run out of steam quicker. The to 50trim is operating within the 65% efficency island, then the power output between that and the 60 trim ill be the same.

I use a math formula for my numbers:

lb/min = BHP x AFR x (BSFC/60)

or

lb/min / 12 / .00916 = BHP


but finding out the max output of the wheel is one thing. You gotta figure out what your engine will output where on that map. If your goal requires the 50 trim to work outside of the efficiency island, you can expect your torque to drop off fast and require a few extra pounds of boost to compenstate. If in that same situation the 60trim wheel didn't reach the 65% mark, then you'd expect your top-end to look signifigantly better.
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Old 08-30-2007, 04:46 PM   #6
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so if both are set at 12psi with 2.5in dp, 550 injectors, Link, and NPR IC, the 60 will simply be more efficient without making it work as hard as the 50? I think I knew before I posted, but just trying to justify spending the money I guess. they will both spool the same, so no loss with the 60 in that regard. I think I'll bite the bullet.
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Old 08-30-2007, 04:56 PM   #7
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Where are you buying from?
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Old 08-30-2007, 05:23 PM   #8
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Quote:
Originally Posted by zoom2zoom View Post
so if both are set at 12psi with 2.5in dp, 550 injectors, Link, and NPR IC, the 60 will simply be more efficient without making it work as hard as the 50? I think I knew before I posted, but just trying to justify spending the money I guess. they will both spool the same, so no loss with the 60 in that regard. I think I'll bite the bullet.

ok that gives me somethign to work with, from experience i made 200rwhp at 11.5psi with a shitty exhaust. so lets say you want around 230BHP.

230 x 12 x .00916 = 25 lb/min

so somewhere around 200rwhp will require 25 lb/min.

lets plot both for 12psi and 25 lb/min:






what this tells me is the 50trim when approaching redline will start to drop off in useable efficiency and your torque will drop and the HP will remain horizontal and not continue to make power, whereas the 60 trim wheel will stay within it's efficiency island to redline and thus more HP.
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