HPF Chris
04-22-2009, 08:06 PM
I took my M3 out this past weekend and did some pulls on the freeway with 3 Lambo and Ferrari owners in the car. I had a VBox in the car, and even with all of them and a 150 lbs stereo the car pulled 0.4G's at 130mph! They definitely seemed to enjoy the ride!! One of them was a driving instructor at Portland International Raceway and he said he's been in some extremely fast supercharged Vipers but he's never been in anything this fast. I'll post the VBox numbers and video when I have some free time.
Anyway... to the point of this thread. There is a limit as to what the standard ARP head studs can handle. Until now, we've upgraded all of our built motors (stages 2.5, 3 and 4) to the standard ARP head studs (tensile strengths between 180,000 and 210,000psi). In all cases thus far we've been able to torque the head studs down enough so that the head doesn't lift. The way you know you've exceeded the studs capability is either #1) you torque the stud and it never achieves the desired torque setting because it stretches or #2) you do a high boost pull and you see or smell coolant coming out of the overflow tank. This happens because cylinder pressures escape when the head lifts and go into the coolant jackets superheating the coolant.
Now that we've finalized the stage 4 tune and the power is a flatlined 840rwhp from 6,000rpm to 8,000rpm (see below) there is considerably more stress on those bolts especially when doing long pulls through several gears. During some stress testing we managed to lift the head for a brief second. This didn't do any damage to the engine but we knew it because a small amount of coolant came out of the overflow bottle.
The good news is ARP came out with an extremely strong head stud called the L19. These are made with a very high strength steel compared to the standard 8740 ARP's and the ARP2000's. These L19 studs are capable of delivering clamp loads in the 230,000-260,000 psi range. The bad news is they're VERY expensive and are special order with long lead times. However, we ordered 15 sets several months ago for the S54 engine and they just came in today. We are now replacing the head studs on both the HPF M3 and on My Trans stage 4 M3. Our stage 2.5 and 3 motors don't require these studs because the cylinder pressures aren't high enough to stretch the standard ARPs. Even so, from now on, ALL HPF built motors will use the L19's because we have them in stock.
Here's the Stage 4 dyno graph to show why there's a need for the studs.
http://www.horsepowerfreaks.com/miscellaneous/m3turbokit/hpfm3/HPFM3_843.gif
Here are the new ARP studs. For anyone that has seen ARP head studs before, these will definitely look a bit different. :)
http://www.horsepowerfreaks.com/miscellaneous/m3turbokit/arp/ARPL19.jpg
http://www.horsepowerfreaks.com/miscellaneous/m3turbokit/arp/ARPL19_2.jpg
Anyway... to the point of this thread. There is a limit as to what the standard ARP head studs can handle. Until now, we've upgraded all of our built motors (stages 2.5, 3 and 4) to the standard ARP head studs (tensile strengths between 180,000 and 210,000psi). In all cases thus far we've been able to torque the head studs down enough so that the head doesn't lift. The way you know you've exceeded the studs capability is either #1) you torque the stud and it never achieves the desired torque setting because it stretches or #2) you do a high boost pull and you see or smell coolant coming out of the overflow tank. This happens because cylinder pressures escape when the head lifts and go into the coolant jackets superheating the coolant.
Now that we've finalized the stage 4 tune and the power is a flatlined 840rwhp from 6,000rpm to 8,000rpm (see below) there is considerably more stress on those bolts especially when doing long pulls through several gears. During some stress testing we managed to lift the head for a brief second. This didn't do any damage to the engine but we knew it because a small amount of coolant came out of the overflow bottle.
The good news is ARP came out with an extremely strong head stud called the L19. These are made with a very high strength steel compared to the standard 8740 ARP's and the ARP2000's. These L19 studs are capable of delivering clamp loads in the 230,000-260,000 psi range. The bad news is they're VERY expensive and are special order with long lead times. However, we ordered 15 sets several months ago for the S54 engine and they just came in today. We are now replacing the head studs on both the HPF M3 and on My Trans stage 4 M3. Our stage 2.5 and 3 motors don't require these studs because the cylinder pressures aren't high enough to stretch the standard ARPs. Even so, from now on, ALL HPF built motors will use the L19's because we have them in stock.
Here's the Stage 4 dyno graph to show why there's a need for the studs.
http://www.horsepowerfreaks.com/miscellaneous/m3turbokit/hpfm3/HPFM3_843.gif
Here are the new ARP studs. For anyone that has seen ARP head studs before, these will definitely look a bit different. :)
http://www.horsepowerfreaks.com/miscellaneous/m3turbokit/arp/ARPL19.jpg
http://www.horsepowerfreaks.com/miscellaneous/m3turbokit/arp/ARPL19_2.jpg
