Blazekillerace

I'm just curious as to what other 450hp-500hp C3's run in the 1/4 mile? What is the typical trap speed? Just wondering, because I have a friend with a WRX that trapped 114mph, did a little research, that's around 360awhp. I would like to beat him, if possible with my current setup... At least from a roll (on a closed course). But some have told me I'll have trouble trapping 110mph even with traction.

My engine is a 383 Stroker stage 2.5 from Skip White Performance. Rated around 475hp. My engine I bought isn't listed, but this one is damn near identical. http://www.skipwhiteperformance.com/detail.aspx?Item=383_STG2_0
I might upgrade some of it during this winter. Might get afr heads and slightly bigger cam, want to breach the 500hp area..
My car is running a built TH350 with a shift kit, a Transmission Specialties 3200 Stall torque converter. it also has 3:32 gears (I believe). I did the rotation years ago, just forgot. I know it's under 3:55 gear ratio. Running all season stock size tires. And just bought a 750cfm Q-Series Quickfuel carb.

So what are your thoughts guys? Just want some expert opinions.

dogboy

My guess.C3's are heavy so I'll guesstimate 110-115mph if traction is good.

Blazekillerace

I did some weight reduction. Removed spare tire lid and tire, Ac deleted, aluminum heads/intake etc, getting a aluminum radiator as well. I think I lost a good 150-200lbs, I plan on doing some other things as well. But I was thinking around that mph as well.

Reason why I'm concerned with mph, is because it's a near Indicator what my car is putting down. But I would like to find out how to improve my engines top end as well. I'll have to search around.

03bluemule

You can go to Wallace calculators, google it . there numbers are pretty close !

tektrans

Gears aren't ideal. I'd say mid 12's as a baseline then you can chip away at it from there.

dogboy

Yea that was my thought also. move up to 3:73's

Blazekillerace

I agree. Sadly I think I'll have traction issues right off the bat. Increasing the ratio might make my current problem even worse. Unless I race from a roll. But I can't imagine going from 3:32's (I think) to 3:73's to be a huge game changer. Only one way to find out I suppose. lol

ajrothm

On some MT ET street drag radials, I could see you dipping into the mid to high 11s @ 112-114 assuming your engine makes a GENIUNE 475hp and your converter is somewhat right...

I wouldn't even waste my time racing on regular street tires...

Blazekillerace

I've had the engine dyno'd, it was 473hp to be exact.

Either way, if my car traps that low, it looks like I'll have spend more money on the car. Figured 450+ would be good enough for decent traps. Did think about putting in a 700r4 tranny in. Still debating, people told me it might run even slower.

Or maybe buy a newer gen vette as a project.

ajrothm

Your car will run quicker with the T350. Less weight, less parasitic loss..
The converter will be the key in how well your car ETs and trap speed. Car weight has a lot to do with it also..

475 crank hp at 3600lb race weight MAY go 115 mph if everything is right on the car and the DA is killer..

Figure your car puts 350 rwhp to the tires...at 3500-3600 raceweight.

A C5Z makes 350-360rwhp and traps 115-118 mph at say 3300lbs...--hence why I guesstamated 111-112in reality. Still damn good. Mid 11s on pump gas at full weight is very respectable.

However, you won't know til you do it.. I've seen this a thousand times... "On paper it should run xxxx" and in reality it doesn't run anywhere near that. Especially on the first trip out with no tuning.. I wouldn't be surprised to see you go 108 mph first trip out before you start tuning it and maximizing everything.

Good luck!! Keep us posted on the progress.

Blazekillerace

True, the TC setup was recommended from transmission specialties.

Agreed, that's why I started to do some of Bee Jay's C3 weight reduction ideas, he has a thread somewhere. I just did basics, like spare tire removal, aluminum engine parts, aluminum radiator, and hoping for some aftermarket seats. I figured with all that I should've lost at least 100lbs.

I'm just slightly confused on how a car that traps 110ish can run mid 11's? To me it would seem like my car dies on top end. Mid 11's would be cool, but if it traps 110mph, I don't see how it can accelerate fast enough to get into the 11's. Then again I'm new to the drag racing scene.

I'm sure nearly everyone has had a roll race from time to time.
That's why I'm concerned for trap speed as well. 1/4 mile I know the car will never hook on skinny 255's. basically what I'm saying is it'd be a bummer knowing after a certain speed my car just dies in the power department. lol

But yeah I don't expect to get great results, practice makes perfect. And thanks for your input, very informational. And I'll be sure to keep you guys posted!

BKbroiler

I have a 77 C3 with TH350 trans. Car weighs 3,400+ with 1/2 tank of gas, no spare tire. I've run 110 a couple times, with 60 ft times in the low 1.7s. ETs were in the 12.15 to 12.20 range. My car hooks and leaves with zero wheelspin.
Reading thru this thread, ajrothm is saying 111 - 112 mph could get you in the 11s. I agree with that, but I don't think 110 will get you there.

Blazekillerace

I'm guessing you're in a similar hp range as mine? In any case, I can't see a 1-3 mph difference being a near a whole second difference in et. I just want to know what is holding the car back from having decent traps? A stock 2010 camaro ss trap's around 110mph with 3800lbs of weight (400lbs more than me) and 50+hp less than me. It would suck knowing a stock camaro would beat my car with less power and more weight. As I said, my friends wrx ran a 13.24 @ 114. If my car will trap lower than his, than he has the faster car. I just figured I'd have a chance considering I'm putting down 60whp more than him and only weigh 200lbs more.

I'm thinking it's the trans that holds the c3 back. Power is power, if two cars both made 400 rwhp, the only thing that could be a game changer is weight and gearing. I do plan on fixing up the engine for more top end, with different cam specs and different heads.

BKbroiler

The car that wins the drag race is the car with the quicker ET, regardless of the trap speed. Your buddy's WRX running 13.24 at 114 would be a small image in my rearview mirror at the finish line, even though I'm only doing 110. Also, at 12.1 seconds into the race, when I'm at the stripe, he would not be doing 114, since it takes him 13.2 seconds to reach that speed.

Blazekillerace

True, and I'm sure his car would lose to yours. But his car should be capable of 11's as well. That run he did was his first time and even had a passenger. Trap speed is a good indicator of how much power you're putting down. I've researched on wrx forums what is needed for 11's, most guys were trapping around 114-116mph, which means if he launched perfectly like me, and neither of us mess up, he will beat me because he's going faster. Not that I'm try to argue, but me racing my buddy doesn't look like it'll turn out pretty for me. I need to get my c3 to trap higher, which I'm guessing means I'll need even more power..

I'm just disappointed in what my car is going to perform like. Like I said, maybe I should pick a different platform to mod and just make this car a weekend cruiser. None of this is me arguing, just was shocked at the responses. lol

tektrans

The lower your 60' ET the lower your mph will be.
If your buddy is trapping 114 spinning the tires then he would trap lower if he hooked it but it would ET better.

My car went 11.95 on street tires with just a little wheelspin (1.7 60') and higher gears and trapped 120mph-that was in the heat.
Some steeper gears and drag radials no wheelspin (1.5 60') car went 11.3 @ only 117mph and that was in cooler weather.

Yes mph is a good indicator but only if the car WORKS at the track as it should-meaning traction, gearing, shift points etc. are all optimized and car leaves the same way everytime with no wheelspin, no babying the clutch, no pedaling etc.

Any wheelspin or the other factors mentioned here then it just turns into inaccurate assumptions on what the car will do optimally.

Blazekillerace

See, I use to think that as well. But it seems like on a lot of forums, it's a whole debate whether "lower 60' results in lower trap." Some say if you have a quicker 60', you're accelerating quicker, and therefore higher trap. Where as spinning the tires won't allow you to accelerate as much. But, there are a lot of people who say what you're saying as well. Quicker et results in lower trap due to get to the finish line quicker and not optimizing top speed. Which makes sense to me as well. Both cases seemed to be defended. But I see where you're coming from, and does make sense.

As for my car I plan on getting steeper gears as well, take put my current gears for 3.73's, I'm hoping it'll help keep my th350 closer to my powerband during shifts. But traction becomes a bigger issue. So I might suspect worse et.. But you made really good points, which I never fully considered. Obviously the best solution would be to go out and test, once she's done.

tektrans

I think it's because the actual "speed" of the car going through the 60' mark is higher in a car spinning the tires or and under geared car, or over tire'd car. Yes it may take you longer to get to the 60' mark but the speed of the car will be higher once it gets to that mark-hence higher mph up top at finish.
I think....Lol

dennis50nj

Wallace Calculator
Enter your 1/4 Mile ET/Speed and Weight of your car
ET: 10.163
MPH: 131.08
WEIGHT:3260 with driver

Your HP computed from your vehicle ET is 552.44 rear wheel HP and 613.82 flywheel HP.
Your HP computed from your vehicle MPH is 529.18 rear wheel HP and 587.98 flywheel HP.

You can see they are way off the times were done with the 487 rwhp with the 1 3/4 headers

ajrothm

BlazeKillrace, Just get the car to the track and start working on it.. You're disappointed and you haven't even ran it yet..

Yes for roll racing, trap speed rules, no doubt.. Trap speed is a result of HP/WEIGHT primarily....also aerodynamics, parasitic losses etc etc.. I will tell you that your car will not likely be a great roll race car, especially against late model cars that make considerably more power, better gearing and lighter... Your car however, will leave hard at the track. A stall converter will eat up mph...that is why you can run a bottom 12 at only 108-110 mph.. The car leaves better because of the loose converter, yet the converter slips on the big end losing mph...This makes it appear to have less HP then you have, you are really just losing it through inefficiency of the converter/drive train.

I used to have a 78' Trans Am with a 406" Pontiac... I'd be willing to bet it BARELY made 400-425 crank HP... Yet the car ran 12.00s@108 mph with 1.60-1.62 60's.. It left hard but was sloppy up top... I still got the stripe first and still won races at the strip. Eventually I got it to run 11.89@110 mph with a 1.58 60' and a -500 DA night. That car was 3600lbs with me in it.**** My point is, it can be done with a lower trap and lower HP, everything has to be maximized...

As for hooking on a "tiny 255 radial"... on a good track, they'll hook fine....This is a MT ET Street radial 255/60/15, 1.51 60'


IF you are more concerned with trap speed and roll racing, a tighter converter is what you want, in this instance, you want to do everything you can to reduce weight and increase HP that is actually going to the wheels.. Minimize parasitic losses as much as possible through exhaust, accessories, air flow restrictions... That being said, you'll probably be hard pressed to out run new cars from rolls....They are efficient, make good top end power and the drivelines don't evat up a ton of power.

I have a buddy with a "cam only" LS3/auto C6 and he gives me fits in my 71' from a roll....he eventually pulls be after 135 mph on the highway..

Gotta decide what you want to do with the car... If you wanna drag race it, get to the track and get a baseline, then go from there... Get the check book out, its about to get expensive.... Rear IRS stuff will be the first to go..