I have a 90 mustang coupe I built from scratch. built mostly for street/strip duty. It has the following: std bore 302 roller 1/2 filled w/hard block,balanced assembly, arp bolts/studs throughout, scat 5.09" capscrew rods,forged trw's notched for 2.05"/1.60" valves 9.7 comp,ported world sr's(2.05/1.60 valves)flowing 286@.600". tfs stage 3 cam(.574"/.595" 232*/246*@.050"), comp short travel hyd roller lifters, comp springs and pushrods,scorpian roller rockers(1.6)parker funnel web intake,650 Holley dp,1 3/4" long tubes w/3" exhaust/ locked timming at 36 degrees,msd 6al/multi stage retard box,c4 trans,4000 rpm converter, 4.30 geared 8.8 with a full spool and 31 spl axles, megabite jr lower bars and uppers.16 gal fuel cell. 1/2" fuel lines, Holley blue pump set at 6.5 psi. 3000 lbs.. 275/60-15 BFG drag radials. It has run a 12.8 @ 107 mph so far. I feel it has more in it,I have a small 2 stage nitrous setup(100/175) but want to get it runnung good on motor before I hit it with the juice. what would you suggest?
a few things until some of the others chip in...multistage retard... is that in use without the N02..???that number bfgdr shows 743 turns per mile...do you have any friends with some 235/60R15s mounted on rims that will fit your car.. those show 794 turns per mile..275/50R15 at 791255/50R16 at 793275/40R17 at 805these would get you out of the hole quicker...i will kinda expect you to check for tire clearance before getting to the track if you borrow a set..if you don't have disc brakes on the rear.. you might even go stranger.. to a smaller rim and really low profile tires.. if somebody has some.. this is like putting in lower gears.... gets you out of the hole easier.. switch back to the taller tires for street operation.. in addition.. to lower gear or shorter tires.. to improve leverage at the take off.. you might also want to borrow a larger carb... for race nights... so it won't be running out of air at high rpms..can you post your 60 foot times.. if you have some..
I Had 4.56's in it and went to 4.30's for when I use nitrous. I have a 750 dp carb. the retard box is for nitrous use. I have a set of 28x9 M/T slicks on 15x8 draglites with screws that I have'nt used yet. they're really 27.25 tall. last time I had it out it did 1.873 60'on the drag radials at 15 psi. thinking about getting some Hoosier 26x10 slicks over the winter. rear tire clearance is not really an issue, running drag springs that sit a little hi right now. have air bags too. gonna cut a coil out to lower it some.
Be carefull with nitrous it has a mind of it's own.Bob
Jack Roush makes some really nice Superchargers. Thats one way....Safer then nitrous...Bob
at 12.8 seconds if you had slicks on .. you should be running a 1.77 60 foot time..thats on 1/10 off.. what kind of RPMs are you running.. when you pass the finish line???when you went from the 4:56 rear end to the 4:30 gears... what happened to the 60 foot and the ET/mph did it the car go faster or did it slow down.. i know its JUST a 302... but you have dumped wads of money into it.. and it seems that it should go faster from what i can see.. perhaps there are some members over at 5.0 mustang magazine on this site other than me who know a lot more about drag racing the 5.0 mustangs..... there are 4 mustang specific magazines in case you did not know..by the way.. do you know exactly how much your car weighs.. ??????
it was 2980 lbs w/o me with 8 gallons of gas(I'm 265 lbs)= 3150 lbs +/-.. have not been back to the track to compare the gear change et/mph. ran best times revving to 6900-7000. had a comp solid roller in it before(.586/.586 246*@ ,050") it ran 12.40 @ 110.8 with 4.10's and small 26" hoosier dirt boss dot tires. it crossed the traps @ 5800 rpm. with the 4.56's and 27.5" BFG d/r, it was 6150 rpm. the intake and cam are too big, but I'm working with what I have. I'm surprised this motor is running this good. it was in my 87' GT(147000 miles) did'nt need an overbore! put scat rods and lighter piston pins, had crank polished and the oil holes scalloped, had it balanced w/ cfi rated flex plate and balancer. it has been to 7000 more times than I can count. I built this motor on a budget and whoop my buddy's G-body street cars all of the time.
let me put up some numbers... and i may have gotten this wrong.. 4.10 Gears 26" tires5830 RPM @110 MPH or 3179 @60 MPH4.56 gears27.5 tires6129 RPM @110 MPH or 3343 @60 MPH4.56 gears26" tires6432 RPM @ 110 MPH or 3556 @ 60 MPHyou kinda negated the gear change by going to a taller tire...find a set of 26s... see if it perks up.. find a set of 25s. perhaps too many RPMs.. that would put the RPMs at 6742 at 110 MPH.. this is a straight calculation.. not including any slip if there is any in the torque converter at that kind of RPM.. i just calculated out that a former camaro was spinning 7800 in the lights... SJ327..i first answered you without the use of the calculator...http://www.wallaceracing.com/calc-rpm.php
I did not try 26" tires with the 4.56's `,, I'm trying to get ready for nitrous, increased mph/rpm(115-119 mph). dropped gear cause everyone kept telling me that my block can't handle the rpm's I've been taking it to. 550 hp/7000+ rpm is the accepted limit for the 302 roller blocks. so I tried to adjust the rpm for a max of 118 mph and 6500 rpm max.
went this past sunday, it ran 12.82@107 mph. not much different than with the 4.56's. so i guess it's running consistant (5 runs). I been told I have too much intake and to try a vic jr or, a stealth or an rpm airgap. they should boost low rpm torque. I made up a 2 stage nitrous system that will launch on 75-100 hp shot then go to a 150 shot via a button on my shifter in 2nd gear. the BFG drag radials only gave modest grip at 13-15 psi. using my MT 28/9 et drags next time out. I got an new NX plate to try next spring. still, 12.82 is good for a low compression/small cube motor. none of my buddies cars can out run it with 350 chevy's. I only have $4200.00 in the whole car!