blue_leaf Posted February 19, 2007 Share Posted February 19, 2007 How much power and torque can I approximately have at the motor before I start twisting my chasiss past its elastic limit? Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted February 19, 2007 Share Posted February 19, 2007 Oh crap... now you've opened a can of worms... But I'm interested... and listening. Quote Link to comment Share on other sites More sharing options...
stony Posted February 19, 2007 Share Posted February 19, 2007 Mine started cracking the pillars above the rear 1/4 windows when i was at 350rwhp. if you wanna keep it straight i would say anything above 300rwhp needs something to beef the body up. Quote Link to comment Share on other sites More sharing options...
strotter Posted February 19, 2007 Share Posted February 19, 2007 Personally, I think even a bone-stock 30-some year old Z needs chassis support, but that's just me. My un-stiffened 72's in the 350 hp range, and I must say I believe I can feel it flexing just a bit - or maybe it's my imagination. Keep in mind it still has a stock diff in it, so torque tends to become tire smoke before it becomes velocity. Quote Link to comment Share on other sites More sharing options...
nat0_240_chevZ Posted February 19, 2007 Share Posted February 19, 2007 i thought it was torque numbers this fellow was asking about!!!!! depending on the rust content in the car, also any reapairs or fixups that have made the unibody stronger/weaker, depending on what day the car was made etc, ie longer spotwelds on modays and fridays lol. id probly say that upto approx 300-350ft/lb and beyond would be around the mark where you start to notice the twist! youre right about a 'can of worms', heres 1, my 340hp bike motor on alcohol only has 100Nm of torque!!!! revs...well thats another story. Quote Link to comment Share on other sites More sharing options...
eec564 Posted February 19, 2007 Share Posted February 19, 2007 Stony - What tires were you using? With regular long-lasting street tires (205/70R14) I can't get enough power to the ground to cause flex. My GF's miata flexes a HUGE amount, not from the engine but from turns and bumps. Quote Link to comment Share on other sites More sharing options...
stony Posted February 19, 2007 Share Posted February 19, 2007 i thought it was torque numbers this fellow was asking about!!!!!depending on the rust content in the car, also any reapairs or fixups that have made the unibody stronger/weaker, depending on what day the car was made etc, ie longer spotwelds on modays and fridays lol. id probly say that upto approx 300-350ft/lb and beyond would be around the mark where you start to notice the twist! youre right about a 'can of worms', heres 1, my 340hp bike motor on alcohol only has 100Nm of torque!!!! revs...well thats another story. How much power and torque I would have quoted torque numbers to if i could remember them. Stony - What tires were you using? At the time i was using 275 x15 x 50 BFG drag radials. Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 19, 2007 Share Posted February 19, 2007 Not to say it doesn't twist, but I haven't had any problems with over 550 rwtq Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 19, 2007 Share Posted February 19, 2007 Search "chassis stiffening" or "chassis bracing" and you'll find TONS of info on this subject. I think you can put a lot more load on the chassis turning it than you can with a big motor, and I've seen enough cracked B pillars on Zs with stock L24's to back that up. Until someone actually does some scientific tests of deflection we really don't have a good answer to this question. So it becomes more a matter of degrees. Do you want your chassis extremely stiff? Do you care? It's all up to you. I can tell you that the difference when adding a strut tower bar is night and day (if you like to turn). When I used to race the guys at Maximum Motorsports they did test the amount of flex on the Mustang. One of the guys who worked there told me that they made a rig where they could put torque to the crankshaft and then measure with dial indicators the chassis flex in various places. Basically it was kind of like a long breaker bar which they would use to put torque to the crankshaft. I can't remember much about what they found, other than I seem to remember that the transmission tunnel flexed almost 3/8" at 350 lb/ft. Then they made K members and subframe connectors and added different roll cages and other pieces and retested. Quote Link to comment Share on other sites More sharing options...
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