Motorgen - Automotive Events, Meets, Cruises and Forums - Verdict is in, I should be in 700hp territory.

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- - Verdict is in, I should be in 700hp territory. (http://www.motorgen.com/forum/showthread.php?t=8606)

enkeivette

10-02-2009 09:52 AM

Verdict is in, I should be in 700hp territory.

With the stock diff!

Quote:

Originally Posted by pcf_mark (Post 54407)

Fact: for every 14.7 lbs of boost an engine will double it's naturally aspirated output. A 300 HP engine natrually aspirated will make 600 HP with 14.7 lbs of boost. Of course there are increased pumping loses etc but you get the point.

In your example the engine made 432 Hp with 5 lbs of boost or 1.33 it's naturally aspirated value. This is 432/1.33 or 324 naturally aspirated.

With 13 lbs of boost you are 13/14.7 or 1.87 the naturally aspirated value. This puts you at 324*1.87 = 608 HP at rear wheels or 711 HP at the crank (using 17% loss)

Plus any gains you made from tuning or tweaking but boost makes up for many ills. AFR of 15:1 you are lucky your rings and pistons are still alive! Blowers like to run rich so it is posible you pciked up 30 - 50 HP going to 12:1 alone.

Which is interesting because the motor made 315 at the wheels NA with the similar crappy AFR when I made 432.

joedls

10-02-2009 10:08 AM

It's not that simple. Power increases due to boost are not linear. There are many other factors in play.

Vettezuki

10-02-2009 10:59 AM

Quote:

Originally Posted by joedls (Post 33830)

It's not that simple. Power increases due to boost are not linear. There are many other factors in play.

The doubling per one bar of pressure is a rough, but fair rule of thumb. Obviously things like intercooling make quite a difference, but it gets you in the ball park.

joedls

10-02-2009 11:14 AM

Quote:

Originally Posted by Vettezuki (Post 33835)

The doubling per one bar of pressure is a rough, but fair rule of thumb. Obviously things like intercooling make quite a difference, but it gets you in the ball park.

All things being equal, that may be true, but common sense says all things can't be equal. You are increasing air charge temps, which you have to compensate for by pulling timing, adding fuel, etc... You can run much more timing on 5 lbs of boost than you can on 12. You can also run leaner at 5 PSI than you can at 12. You also have to take into consideration the blower. How much parasitic loss are you going to experience from having to turn that blower? That will vary with the blower, but every blower will have some parasitic loss. If you add an intercooler, then some of these factors don't have as much of an effect. But we were talking abot enkeivette's car, which I believe doesn't have one.

BADDASSC6

10-02-2009 02:25 PM

That is a rough rule of thumb that losses it's accuracy as you increase boost. The fact is due to heat of compression, the higher the boost the more heat is generated and the increase in the mass flowrate of the air gets smaller. Just because the pressure gage reads 1 bar doesn't mean that you are getting double the mass flow rate.

BADDASSC6

10-02-2009 02:27 PM

I put my money at 550whp!!!!!!!!!!!!

Vettezuki

10-02-2009 02:33 PM

Quote:

Originally Posted by BADDASSC6 (Post 33853)

I put my money at 550whp!!!!!!!!!!!!

Having ridden in the car and making a wild seat of the pants judgement, that's what I'd guess too: 550-600. Still the fastest accelerating car I've been in. :thumbs_up:

94cobra69ss396

10-02-2009 03:15 PM

Quote:

Originally Posted by BADDASSC6 (Post 33853)

I put my money at 550whp!!!!!!!!!!!!

I second that.

Ben, you need to go for a ride in the Chevelle on the bottle with the slicks on.

joedls

10-02-2009 03:33 PM

Quote:

Originally Posted by Vettezuki (Post 33854)

Still the fastest accelerating car I've been in. :thumbs_up:

Quote:

Originally Posted by 94cobra69ss396 (Post 33863)

Ben, you need to go for a ride in the Chevelle on the bottle with the slicks on.

I'd put my money on the Chevelle.

Vettezuki

10-02-2009 03:46 PM

Quote:

Originally Posted by 94cobra69ss396 (Post 33863)

. . . Ben, you need to take the Chevelle for a ride on the bottle with the slicks on.

Absolutely. :nuts:

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