ET VS Weight

[Mike C]

I was just reading a thread from a guy on DSMTuners who has been running consistent 12.00s and should be in the 11s this weekend. He just dynoed his car and put down 285HP at 19 PSI on a 14B. His car weighs 2580. It didn't say with him in it or not. It just gives you an idea of how important weight reduction is in the big picture. Thats crazy fast ETs for only 285 HP. makes me feel that much worse for having 395. Time to start cutting stuff off the sled :p

[Shearer]

How ya think I feel. I went 11.38 with a 90k mile tranny at a tad over 3400lbs. Best mph I ever nailed was a low 128. Think what I could've done with a good shifting tranny and about 500-600 lbs lighter.

[Gunner]

OH you cry baby. The car is EASILY 500 lbs ligher now, and it still can't beat those ET's of yesteryear. Maybe sometime soon though. :thumb

That said, I think it was Phil Beers who weighed around 2600lbs, and made a tick under 300hp when he ran that 12.02@112 on his 14b.

[Shearer]

OH you cry baby. The car is EASILY 500 lbs ligher now, and it still can't beat those ET's of yesteryear. Maybe sometime soon though. :thumb .

Don't know about that. If I get the right driver, say Fred Flinstone or Barney Rubble, the car might haul ass once again, Center Foot Drive. Until then it will have to wait for big smokey burnouts and long wheelies. :D

[biglipps66]

Oh come on fellas :)

Its all about full weight and full street look! :D

[DQ Driver]

great little chart here...http://www.taboospeedshop.com/power2weight.htm
and taboo posted this on dsmtalk also FYI

Horsepower required for 5mph gain for 3200-pound DSM:

Trap speed................HP
90 MPH....................stock
90 to 95...................+32
95 to 100.................+36
100 to 105...............+40
105 to 110...............+43
110 to 115...............+46
115 to 120...............+53
120 to 125...............+56
125 to 130...............+61
130 to 135...............+65
135 to 140...............+71
140 to 145...............+77
145 to 150...............+81

[Mike C]

I think his numbers are way off personally. It says on there that you need 379 flywheel HP to trap 115MPH in a 3200 car. I trapped 117 with 395 wheel HP and I'm guessing my car weighs less than 3200 with the weight reduction I've done so far. Maybe I'm reading his chart wrong but 379 HP is about 324 wheel HP which seems like a well tuned 16G type level. I've never seen a car in that HP range that weighs that much trap 115MPH

[BlackEclipse]

The numbers are bogus in the fact that in order to be ALLOWED to go down the track at those continually faster speeds on that chart, you would have to be modifying the car at every stage to satisafy NHRA requirements. At some point all fabric and plastic must come out of the car. At another point, the stock gas tank must come out and that tiny one goes in. At another point a roll cage must go in and the windows must be replaced by Lexan.

Are they talking Engine HP or HP at the wheels?


Anyway.....I just found another formula on the Internet that says that 835 HP is needed ot reach 150 MPH with a 3,200 lb car.

HP = (TS/234)^3 * race weight

or

HP = (TS * 0.00426)^3 * race weight

where

HP = Horspower (of course)

TS = 1/4 mile trap speed

[Shearer]

The numbers are bogus in the fact that in order to be ALLOWED to go down the track at those continually faster speeds on that chart, you would have to be modifying the car at every stage to satisafy NHRA requirements. At some point all fabric and plastic must come out of the car. At another point, the stock gas tank must come out and that tiny one goes in. At another point a roll cage must go in and the windows must be replaced by Lexan.

What does any of this have to do with weight. Truth be told I know of plenty of cars running low to high 7's with full glass and a mostly aesthetically complete interior.

[Mike C]

Mike,

Your formula seems real close. Shepherd's sight has a dyno sheet saying he was making 687 WHP while trapping between 142-144MPH. That would work out to 710 flywheel HP assuming 15% drivetrain loss. Throw on maybe another 100 HP to go 5-8 MPH faster and its probably pretty close.

[Gunner]

I dunno, that 379 mark sounds pretty close for 115 mph. A buddy, ran 12.07@115 on a big 16g, all supporting mods, etc....in a full weight 1g. So those numbers might be pretty darn close when compared to a well-driven 1/4 mile run.

Shep is running his 158mph passes at a race weight of 2650ish now.

[Mike C]

I dunno, that 379 mark sounds pretty close for 115 mph. A buddy, ran 12.07@115 on a big 16g, all supporting mods, etc....in a full weight 1g. So those numbers might be pretty darn close when compared to a well-driven 1/4 mile run.

.


I believe you but I don't think that is normal. I only counted 12 cars with 16g's running 12.09 or faster on
www.dsmtimes.org Maybe on a fully built motor with headwork but I'd say that is not the norm for any full weight 1g car to trap that high with a 16g.

[Gunner]

I know it's not normal, but i also don't see a 16g supporting more than 379hp even with every other mod under the sun. It was stock shortblock, 264cams, VPC, no afc or gcc, mild portwork on the exhaust side, IRC street core, stock tranny, 3" exh. with VPE O2 dump. That's about it as far as mods go.

[Mike C]

I know it's not normal, but i also don't see a 16g supporting more than 379hp even with every other mod under the sun. It was stock shortblock, 264cams, VPC, no afc or gcc, mild portwork on the exhaust side, IRC street core, stock tranny, 3" exh. with VPE O2 dump. That's about it as far as mods go.

Agreed. I guess my point was that a chart like that should be used to make generalizations on and that we could find an oddball car or 2 that might fit his parameters but it isn't an accurate for most cars.

[Shearer]

IRC street core.

Shame shame. Friends don't let friends put IRC intercoolers on there cars. :bash

Greg's car is in no way a freak or an oddball. It's just a car with the right parts, a very good tune at the time, and a driver that used to be able to shift(Maynard not Greg :p)

But Mike makes the point, it's jsut used for generalizations. There are a million and one factors to make the car run good. If one of those is off, that chart just went to shit.

[OWNDJOO]

we'll settle it now. someone pay for me to go dyno my car, and then we'll weigh it. find out how much hp it takes for a 14b to run mid 12's. who knows though. everyone keeps tellin me im definately over the 300hp mark. but idk.

[DQ Driver]

phil beers car apparently weighs 2580 w/ quarter tank of gas and he weighs 185...his car made 266whp on the a dynojet in 12.0xx form

he just put some new mods including..-2G Maf,Super AFC 2,550cc injectors,Upgraded stock Sidemount--2.25" in/out--Dejontool,1.75" outlet elbow, and 2.25" lower I/C pipe-Dejontool, 2G maf intake pipe-Dejontool,-Buschur upper I/C pipe

new dyno #'s 284hp/271tq awd dyno (should be over 300 on a dynojet), he's planning on tracking it real soon