I understand that springs for V6s and V8s are different and there's even different ones for V8s such as the IROCs and 1LEs. I plan on going with Eibach springs but am not sure on which ones would be best in my application. You see, I will be going with a V8 in the car (91 Firebird) but it will be an all aluminum engine, even the block. I'm wondering how much of a difference will that make when considering springs to by. Are iron engines much heavier that they would require different spring weights? And if there are any springs better than Eibach please let me know. My goal is the best handling, fastest, daily driven f-body.

 

Again, I would suggest the Eibach sportline kit. It lowers the most and give the biggest hadling upgrade. As for which type to get, get the V8 ones because whether alluminum or iron, any V8 is generally going to be heavier than a 60* six.

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85 2.8L Sport Coupe 5-speed.
Mods: Hpertech chip and powerstat, MSD 6A-L, Crane fireball coil, Accel Cap and Rotor, Dynomax hi-flow cat and catback system with a dynomax magnum race bullet muffler on the i-pipe, K&N filterchargers, Gutted Air Boxes, 8mm Wires, Eibach Sportlines and Tokiko springs/shocks setup, Global west sub frames, Suspension techniqs front and rear sway bars, and good ole 88 IROC wheels with Kumo Ecstas on em!
"It's not the ricers, it's those damn V8's!"

Wins: 2000 V6 Accord, 69 302 Mustang, 2000 Auto VR6 Jetta, 89 Toyota MR2, 90 Civic Si, 76 350 Camaro, 2000 3.8 5-speed Camaro, ~68 Chevelle 350, 92 CRX Si.

 

The Eibach Pro kit offers better handling than the Sport Line kit. The Sport Line kit is for "looks". The Sport Line kit DOES lower the car more than the Pro Kit, but, it lowers it so much that it negatively affects the geometry of the suspention and thus the handling of the vehicle. For the BEST HANDLING, the Pro Kit is the better of the two Eibach kits.