so i wake up this mourning and of course first day of the season it had rained!!! so i go out there anyways and ther dryin the track. so i wait about 5 hours til about12:30 and they get it dry and then run 3 jr dragsters. guess what it rains again. so they start dryin again and get it dry about 3:00 and now its cold (bout 50 degrees) probly humid and had a good headwind (10-15 mph) and they say 1/8 mile only. so i get a pass in.
'60 1.87
1/8 8.41 @81.65

i wasnt happy.so it getting nicer and they open it up to 1/4 mile.
1.883 60'
8.381 @ 82.01
13.262 @100.03

again i wasnt happy. so i advance timing a couple degrees and run open header.
1.891
8.337 @ 83.8
13.101 @102.49

that was ok but i expected better. it was still cold and windy but i decided to put the exuast back on but leave the timing at the advanced setting.

1.899
8.405 @82.62
13.248 @ 101.16

best last year was
1.914
8.39 @ 84.21
13.122 @ 103.44

humidity hurts performance doesnt it? the time last year we had really good conditions

Nice! Mind giving specs on your engine and car? Thanks

yes humidity hurts performance..its makes air less dense and produces less power..some people rejet for humid conditions(jet down) so their combo wont be running rich

i thought so, it just didnt feal there.

my combo is this
9.5 :1, 355, vortec heads, performer rpm cam and intake, custom modded 750 vac secondary,
th350, 3500 bte converter, 3.73 gears, eaton posi, ssm lift bars, 1 5/8 headers with 2 1/4 pipes into 3 chamber flows.

theni have a sniper 100-150 plate system to use when i get the balls. :D

i feal like ive hit a wall with my combo. it could probly use more compression with that cam. what do you guys think?

post the specifics of the combo as well as you know them.

well its a 355, with vortec heads that are supposed to be about 62ccs, pistons are supposed to be 9.25 hyper, block is decked to 9.020, im runnin a .018 thickness gasket. cam is a perf rpm with .488/.510 lift 234/244 .050 duration not sure on advertised but its about 304/314. performer rpm intake, 750 vac sec holley with choke milled off. 1 5/8 headers. if you need more info ask

What kind of car are you running? I'm interested because I'm looking at vortec combos because my bro might build a vortec 355 for his 69 Nova in the upcoming months.

thanks

bout 3450 lb with driver '72 chevelle

From what Pat Kelly says about that cam and dcr. Yes you do need more compression. You could mill the heads and or change to a lower adv duration cam. Put some .100 dome pistons in there. Or just a cam swap.

I checked your combo with Pat's calc. I get in the 10.4 CR range. Used 62cc hd,7cc FT,.020 deck, .018 gsk 4.166 gsk bore, 4.03 350 sbc. Or are you using the 12cc dish pistons? I don't keep track of the 350 stuff. With your CR as I get it, you could try a XE274,280H, 282S or XS. A UD276/284 solid would be my choice. If your in the 9.5 range, a UD272/282 solid might be a better choice.
Let us know what you do. It would be an interesting comparison.

the pistons are 4 valve relief fed-mog hyperutiectic that are suipposed to be 9.35:1 with 64 cc heads

9.85 with my above listed specs and a 12cc dish.

A UD272/282F10 Solid or 272/272. Or a comparable UD hyd. Not that I look at those much. A Isky 274 mega Hyd has a 108 lsa if you want the mid range and some lump. All for an 8.1 or more dcr.
The 276/284F10 at a true 104 ICL is 8.0 dcr.
Which is fine on pump gas, 180 or more thermostat etc w/ vortec hds. I'm at 8.5 dcr and have to do a little tuning to stop knock.

well i have a set of scat rods here so i might just get some new higher compression forged pistons. that way i can run my 150 shot :D

Do you think the 2 1/4" pipes are a little small for your setup?

Matt,what tires are you running?

yeah dropping my pipes were worth .1 and 1 mph and on the dyno its worth 10 hp but i lose about 10 ft lbs. im runnin 28x12.5 mt et street.

28x12.50 is some big tires...what RPM are you crossing at the big end?

12.5 ET street are the same as 10.5 ET drag.

Originally posted by Motor Martyr:
12.5 ET street are the same as 10.5 ET drag. true..just curious if he needs that tall of a tire....300HP, what RPM's?

about 4500 rpms or so, i never really look, just kinda glance. i shift about 5800 i figure on the bottle it should be about 5200-5400 rpms.

Hyperutectic pistons + N20 = hand grenade.

i know there not the best but ive seen people use them and not have any troubles. im more concerned about my stock connecting rods.

Originally posted by 300hp:
about 4500 rpms or so, i never really look, just kinda glance. i shift about 5800 i figure on the bottle it should be about 5200-5400 rpms. can you borrow as set of 26" ET Streets.....will raise the RPM's at more of the peak for you at the big end....

Less tire diameter means you're going to spin more often.

You not only need footprint, but you need diameter as well for traction.

If its under-geared, change the gears, but dont compensate with little tires, and i dont see a problem using 3.73 gears with 28" tires.

Originally posted by Motor Martyr:

If its under-geared, change the gears, but dont compensate with little tires, and i dont see a problem using 3.73 gears with 28" tires. that's why I said 'borrow' and see how the RPM's are at the big end, I agree you need patch, but to borrow a set of 26x11.50 will IMHO set a new best ET..then a gear change would be in order with the 28's smile.gif

You know a short tire is not as forgiving as a tall tire, but shouldn't make you spin just because its shorter -- at least not at this power level. The contact patch is about the same as a taller tire, the shorter tire just has less sidewall and less "tread length" than a taller one.

I run a 3.55 gear and a 26" tall Hoosier with pretty good results. It's just a cheaters way of taking a shallow geared street car and getting a little more out of it at the track IMO.

I prefer to keep mine this way because I drive my car on long trips and can run a taller set of street tires to keep the RPMs down. Now if I had a numerically higher gear ratio and ran a tall tire at the track I'd be SOL on the freeway -- you can only go so tall with any given wheel well.