how much does weight matter?

[94tegRS]

ok, before you say ALOT, I knopw weight is the worst thing in drag racing, I just wanna know if my car weighs 2100 pounds stock, and it has, say 200 WHP(not yet), if i could strip the car and get rid of say 100 pounds of seats and spare and such, would it take off about a 10th of a second only or would it take off more than that?

also, anyone in here with a 2100 pound 5th gen hatch, and turbo CRVTEC with an S80 tranny? if so what do you run on street tires.

I am gonna eventually have a 11.3:1 CRVTEC at about 6 psi(at the track) probably run it all motor daily to save some fuel and some engine life.

[flylwsi]

I am gonna eventually have a 11.3:1 CRVTEC at about 6 psi(at the track) probably run it all motor daily to save some fuel and some engine life.

so you're going to turbo/sc it, but run it n/a daily?

how did you plan on that?

the rule is usually 1/10th of a second for every hundred pounds dropped, but it's not always the standard...

there's other things that play into it...

how much gas in your tank, b/c it weighs about 8lbs. per gallon... less is lighter...

11.3:1 is pretty high compression for a forced induction motor...
requires alot of tuning...

[94tegRS]

I am only going to be going to the track like 3 times a month max. I have headers and CAI for the engine, then on the day before I go race, I am gonna remove headers and intake, bolt up the turbo manifold, turbo, piping, intake from turbo, plug the oil feed line, play with the VAFC for a minute and a freind of mines dad owns a muffler shop and I can get anything exhaust wise at cost with free install. I am just gonna have him make me a down pipe that the flange ends up right where my headers end so I figure after a couple times this will be a quick process.

and about the weight thing, on a heavier car with less power, say a 2600 pound integra with only 170hp or so, 100 pounds would make a bigger cut in the time right?

[flylwsi]

is it worth it to spend a couple hours to put a turbo kit on for just a few hours?

come on now..

and still, at 11.3:1 compression, you'll blow stuff up for sure...

[flylwsi]

and about the weight thing, on a heavier car with less power, say a 2600 pound integra with only 170hp or so, 100 pounds would make a bigger cut in the time right?

the average is .1 second per 100 lbs.

it's not exact, but that's the general rule of thumb.

I am gonna remove headers and intake, bolt up the turbo manifold, turbo, piping, intake from turbo, plug the oil feed line,

what about an intercooler?

are you going to run one?

this doesn't sound like the optimal way to run a car...

if you're going to get a turbo kit, put it on, leave it on, and tune your car.

you just spent 3-4k, don't leave it in the garage

[94tegRS]

I thought that you could boost a high compression engine if tuned properly and of course not a lot of boost.I dont think it will take me a couple hours after I have done it a couple of times. Do you think with 11.3:1 it would be safe to boost 3 to 4 pounds daily driven? Is 4 pounds going to make a noticable difference, I think it would because of the high compression but I want to see what you guys would advise.

[flylwsi]

11.3 is high for an NA street car, let alone a turbo'd car.

you would need hours and hours of tuning to get it to not blow up...

just not worth it for something you're going to take off the car.

consider that the fd3s rx7 tt only pushes a max of 8psi

3/4 lbs wouldn't be bad on a motor, but not really worth it...

neuspeed's supercharger for the 2.0 liter jetta pushes about 5psi.

still, that compression ratio would only get you detonation and blown up stuff...

[94tegRS]

ok, so if I went down to say 10:1 could I boost 7 pounds safely?

and the only reason I went with 11:1 pistons is cuz my neighbor knows alot(and when I say alot, I mean ALOT, at least he sounds like he does, I cant prove him wrong cuz half the time I cant follow what hes saying )

but he said 11.5:1 is the highest I should go running off of 93 octane. so I stayed at 11:1 but the guy at JE told me when I add my B16a head later it will be upped to about 11.3:1 and I used to want to go all motor, but now I think I am going to want to go faster, for some reason nothings ever fast enough to satisfy me.

but a 10:1 boosted 7 pounds would whoop on a 11.3:1 all motor huh? but is the 11.3:1 safer than the boosted 10:1?

and how does a turbo affect the mileage, cuz my mani goal is a car that can smoke most of the cars around (well imports anyways) and still be my daily car getting good gas mileage.

I know I aint gonna run 11's or anything, but I wanna at least hit 12.99 and be economical while I drive normal, I hate putting in 5 bucks a day, I miss the old teg, I hossed it all over and put like 30 bucks every couple weeks, but I didnt run no 12's either

[flylwsi]

if you plan to run 11.3:1, you're going to need some high octane gas, and great tuning...

a turbo'd 10:1 would be like a stock civic si b16 turbo'd...
easier to do for sure...

11.3:1 is high compression for anything on the street, but it can be done.
the turbo'd 10:1 would be easier to tune as well as easier to manage fuel wise.

if you're really worried about the mileage, etc. you're getting into the wrong mods for your car.

a turbo'd motor and a high compression NA motor would have similar mileage, within limits...

either way, it's about the same.
if you are getting the turbo, build the motor correctly for it, b/c it's an easier route, and a faster car overall

[94tegRS]

well, I know that it wont get great gas mileage, but I still want better than my POS stock mustang V6, that thing is slower than a 4 with the mileage of a 8.

anyways, I think I wanna go all motor, or I have to sell my pistons or find someone to trade me my 11:1 for some 10:1.

but If i went all motor this is what I got planned, and I can afford it in about a month, but that money could be spenton just converting to VTEC and add turbo.

crower rods
new bearings
crower stage 2 cams
crower dual valve springs/titanium retainers
310cc injectors (big enough right?)
new fuel pump
B16a head
8.5 pound fly
stage 3 6 puck sprung clutch
70mm TB
skunk2 intake manifold
AEM V2 CAI
TB spacer
AEM cam gears
AEM lightened accesory pulleys
UR lightened crank pully
MSD SCI ignition
Nology Hot wires
Bosch platinum +4
APEXI VAFC
4-2-1 headers
2.25" straight pipe Y'd at axle to dual mufflers (for looks not performance)

but then If im gonna do all that and could have been faster by just a B16a head and a turbo kit at (whats safe? 7-8 psi)

or would my NA setup be close to keeping up. also which would get better mileage out of the two?

[flylwsi]

honestly, the turbo setup will get you more power/speed hands down...

if you're going to swap for pistons, you may want to consider something with compression less than 10:1 just b/c that makes it even easier to tune and run more boost safely...

can't tell what the mileage is like really...

[94tegRS]

alright, well, I think I am going to put in the 11:1 pistons and run it like that with I/H/E for a whiloe, then save up money and do this instead

swap for 9:1
built internals
crower turbo cams
440cc injectors
MSD 6BTM (can you use the BTM module wth any MSD ignition or no?
FMIC
tubular manifold
turbo
etc...


but do you thikn the turbo will run about a second qiuicker at 13 psi? (would built internals and 9.3:1 handle this?)

cuz I heard a crx ran a 12.2 with built CRVTEC and they weigh 9 pounds more than my hatch.

[flylwsi]

come on...
stock internals on a b16 with better injectors and a HONDATA ecu can make about 300hp at 15psi...

you could easily make that kinda power, and 9:1 compression is really safe for that kinda power...

[AC_A340-500]

Back to the original qusetion.

The power to weight ratio is critical when takling about drag racing. Shedding 100 pounds from a 3000 pound car isn't going to yield the gains that shedding 100 pound from a 2000 pound car would yield (all else being equal).

Also, shedding 100 pounds off of a 2000 pound car represents a weight reduction of around 5 percent. this would result in an improvment in the quarter mile time of, say 0.Xx seconds. To have the same improvement in ET without decreasing the weight, you would have to increase the horsepower by about 5 percent. (There are other factors as well like gear ratio, traction, rolling resistance, frontal area of the car, coeficient of drag, etc.) Roughly speaking, that's the effect that power to weight has on accelleration.


(To be more precise, the power to weight ratio determines the top speed at the end of the quarter mile (all else being equal). The correlation between the power to weight ratio and ET is less pronounced, albeit still failry direct)

[dampachi]

wait wait wait...forget the original question....you're going to uninstall a turbo kit? and install it again for race day? dude. what the FUCK are you thinking?! just run really low boost when you aren't racing.