I was wondering the best way to get 450 horse out of my ls1. Can I keep my stock heads? I know cam is a must. IThis motor is going into a 87 Trans Am.

 

400 at the wheels will be near 450 at the motor, a little more.

If you want 450 at the wheels, it'll take a set of CNC heads/other, a big cam, and a Fast 90/90.

Which one is it that you want?

Ben T.

 

i wouldn't even say that the FAST is needed.

a good size cam like the TSP torquer, MS4, FM14 or similar grinds with a set of Dart 225 heads will put you right around 450rwhp with the associated supporting mods.

been done quite a few times.

 

or you could stroke it or blow it...

 

450rw is pretty easy... but costly. Like already mentioned, heads are a must. A large cam, new fuel pump, injectors, headers, and some really good tuning. And once you're putting down that much power you need to think about whats not going to hold up on your car. Like the tranny, rear end, torque arm. And how you are going to get all of that power to the ground... LCA'a, PHB, SFC's, shocks, springs, etc.... its totally doable, but its not cheap.

 

What? That would be 12% drivetrain loss and theres no way the car would only lose 12%

More like 375rwhp would be around 450 to the crank depending on your drivetrain. 12% is way to concervative.

 

Drive train loss is NOT a straight percentage. The amount of power necessary to spin a drive train is fixed with a small percentage increase for friction as the power goes up.

If a 350 hp motor in a vehicle shows 298 rwhp then it takes 52 hp to spin the drive train. That's 12%. If you up the hp to 450 it still takes 50 hp to spin the drive train plus some small additional losses for added friction. Not 67 hp which is 12%.

 

No matter what any fraction it takes is a certain percent and will vary with setups.

But I see where your coming from.

 

Yes, there are fixed and variable components when calculating the loss from engine to rear wheel numbers. The percentage theory is a best guess and most commonly accpeted. The reason it is a percentage and not a fixed number is because while it may take the same amount of power to move the drive train (wheels, gears, belts, etc.) the increased loss comes from the increased acceleration of those parts. If you take your theory to the track a car that doubles it's horsepower should cut it's time in half, right...wrong. The faster the car goes the more forces it has acting on it....that's kinda the same principle.

 

We just did a set of DART 205's here with one of our custom grinds and it made 412rwhp/393ft-lb

Bigger cam would have it closer to 450 and thats with the 205 heads. I really like these heads as cast for stock displacement engines. Theres a lot of power there.

 

what were the specs on the cam...224 range?

 

lower 230's and 580 ish lift

 

23x and only 415rwhp???

to me that kindda stinks...although i guess through an auto and beefy rear it could be possible. but still.

with my 233 cam i'm probably at or just breaking 400rwhp...i would hope i can get more than 15hp from the heads!!

i was hoping for 440 or so after doing the 205s

 

I read an interview with an engineer from GM that apparently had something to do with the 4th gens that stated that 12% drivetrain loss with a t56 and the stock 10 bolt is not outside the realm of possibility. Take that for what you will. I really doubt I will be able to find the source, as it was so long ago, but I do remember the 12% number specifically.

10 bolt straight axles aren't hugely parasitic. Unfortunately, they don't take much abuse either.

 

I was kinda hoping the same thing 412 does not seem like much from heads and cam