i'd prefer something either in DC or MD, since crossing the wilson bridge sucks, but that's the area i'm in... just looking for a place to top off my bottle with a quickness. something in alexandria or right off the loop in nova would be ok too.

 

disregard, i'm good.

 

just a question about your sig.

89 CRX Si
1.6 liters, two camshafts, 9600 RPMs
HP - 174@8250
TQ - 115@7750
E/T - 14.5@95


if you make all your PEAK power at around 8300 rpm.

WHY TAKE IT TO 9500+? its a waste of time and alot of wear on the valve train. You should always shift 1-300 before or after your peak power. everything else is a flat line or the power is falling off.


besides 174whp in a crx is easily a 13 sec car if not a little faster.

 

^ he gotta point, if your not making power up to 9600rpms then there is no point to take it that high, unless you dont like your valve train

 

ok, this has come up before, so maybe i'm wrong about this. here's my best dyno chart, which i think will provide us with an interesting discussion about throwing aggressive cams on a stock block:



ok, the first thing to note is that i don't make dick for power below 7000 rpms. it's also worth noting that when you slide the powerband upwards without changing the final drive ratio in the transmission, 1/4 mile times don't improve as drastically... that's why people running ls/vtecs with the stock LS transmission bitch about their long gears; they may have added 40 hp, but their gearing is all off... so is mine. plus i suck at driving. combine those three factors with a stock clutch and you've got yourself an embarassing 14 second car.

ok, now the graph itself. you'll notice a dip at 6500 rpms, where my vtec x-over point is. this is due to the fact that the stock compression ratio can't fully support the "high end" vtec lobes until about 7000 rpms, but the stock ecu (i'm running a vafc) freaked out when we set it that high, so we compromised at 6500. so up until 7000-ish, the 10.2:1 ratio is much happier using the low end lobes.

now, and this is the part i may be wrong about, but i still make 150 hp at 9500 rpms. that's pretty good, and it's clear that the cams have more in them than the bottom end can support. most motors drop off quickly after the peak hp point, but this one slowly tapers off. so stock clutch + 15 year old transmission with insufficient final drive gear + crappy driver means i drop about 2500 rpms between shifts. so if i shift at 8500, i drop below the vtec crossover point and into snooze-land, but if i shift at 9500 rpms, i drop to about 7000 rpms, which is as low as the engine is comfortable on the aggressive cam lobes.

whew... so, i think this is worth a discussion... have i made my point? i've tried shifting lower at the track, and it noticeably hurts my times. i think i've got it right. thoughts?

 

yea by 8k your power band falls off. shift the fucker... your slowing down. You might not be loosing speed but your not going faster then you would if you shifted the car and were back at like 6500-7000rpm.


besides vtec should be adjusted for 5500 i would think. your waiting to long.

 

what cams you running, your vtec Xover is kinda high

 

kinda....?

 

well if he is using buddy club stg 3/4, skunk 2 stage 2, jun stage 2's cams, his vtec Xover should be around 6000, if he is using more aggressive cams like jun3's, skunk 3's toda spec C's/d's his vtec X over should be around 62-6500 (which should be correct), if its more mild like ctr or itr then 55/5700 should be the X over point

 

i've got skunk2 stage 2 cams, and i would agree that the crossover point with them is usually around 6000, but hey, every motor's different. we started at 5500 and moved up from there, but we could not get rid of that damn dip. i really think it needs to be set at 7000 until i up the compression, but it hits a rev limiter if it gets that high without vtec engaging. i mean, tuning the vtec engagement point is just as mindless and easy as tuning the rest of the engine... you run it on the dyno, and look for either a dip or a jump at the crossover point. if it dips, move it up. if it jumps, move it down. there shouldn't be any sign of it on the dyno... reference one of my friend's gsr w/bolt-ons dyno (i don't know why they shut down so early, but the lack of any anomolies at the vtec crossover point is what you should be looking at):


now, about me shifting, how can you say i should shift at 8000? the stock redline for a b16 is 8200, with peak power coming on about 7500. so if honda says you should shift 700 rpms past the power peak, and i peak at 8300, then i should be shifting at 9000, which i would probably agree with if i could shift fast enough. the extra 500 rpms just helps keep me in my power band while the clutch catches up. and in reality, the thing is revving so fast at that point that i start moving my hand when i see 9xxx on the vafc, so i'm sure i don't make it all the way to 9600 every time. it's just a mental target for me.

shifting to stay in your power band is all about calculus, and the area under the curve. if you shift right when you're making peak power, you're losing out on all the healthy power you're making after that by dropping down below your power band.

besides, i'm not worried about the valve train... SS valves, upgraded springs, ti retainers... really my only concern from the revs is wearing out the bearings, and that would just give me any excuse to finally rip into the bottom end.