Hi guys, I am trying to correlate rwhp and quarter mile ET for c4's

Could you post your RWHP, ET and MPH if you know them?

Oh and tranny too.

Thanks in advance.


-Mike

 

There are a multitude of calculators out on the web that will "estimate" ET or HP.

However at the risk of sounding ignorant, lots of times the two do not match very well - which is topic of debate many times through the year on this forum.

I am going to request in the near future a submital of combinations for selection and posting, similiar to what BeachBum had on a website that was a collection of some of the best COMBOs for corvette for performance.

However lets see what you turn up here in this post. Should be interesting. My bet is you get a BUNCH of HUGE hp claims that don't even come close to matching the ET/MPH they should be running.

Hint, you should also ask for race weight. That has a HUGE bearing on the ET you can run with a given HP.

Here are mine to start things off.

406 MOTOR:

11.02@123 MPH 1.49 60' times. 436rwhp/536ft-lbs (dyno on website in sig below as are more specifics to this combo)
pro-built 700r4

434 MOTOR:

10.15@134.9MPH 1.37 60' times. Estimated 600HP
pro-built 700r4, Rossler Turbo350 (no appreciable diffence between the two)

race weight for both cars 3400 lbs

 

You will likely find a bigger correlation between HP and MPH than you will with E.T. Traction has a huge affect on E.T. whereas MPH tends to be more constant.

12.732 @ 115.87

379.9 RWHP @ 6160 RPM
356 RWTQ @ 4100 RPM

6-spd manual, 3.45 rear, street tires

 

285 hp and 303 lb/ft at the wheels.

My best time ever was a 12.97 and my best mph was 109.29.(not on the same run).

Stock LT1 six speed with Michelin Pilot XGT Z4 tires in the stock sizes.

-2500 DA

 

With my vette.

305 RWHP. 12.92 @ 108.5. 6-speed, stock weight, plus my 180lbs.

With my Nova
480 CHP. 11.31@117. TH350, 3800 RPM Stall. 3600lbs with me in car.

 

Wondering if altitude/DA should be added, makes a huge difference in times.

 

425rwhp, 11.61 ET 119.3mph
4L60 with 2800 Vigilante
1800DA, 60' 1.7's

 

 

I agree it makes a huge difference, but you need to consider the scope of the experiment. The more variables you have, the harder it can be to determine any trends. You have to consider for yourself how much data is "good enough" for the problem at hand.

 

Lets post factory rated HP and track times?

That would make about as much since as comparing RWHP in a variety of vehicles/setups with track times

 

Stock 86 L98 A4 130K Miles
DA corrected 13.80 100MPH

 

As you can already see there are HUGE differences in obtained HP figures and what MPHs are obtained when you hit the track.

I know what my motors make and are capable of making based on TONS of research comparing to other setups and comparing HP numbers from very reputable engine builders.

Comparing my 406 that ran 123MPH with 436rwhp, you can quickly see that others stating near the same HP are nearly 10mph off even with manual boxes (usually produce 3mph higher MPHs).

That is why I say if you want to find your USEABLE HP rating of your car, take it to the track and on the return road, stop in at the scales, get a good weight of your ride, and go home and calculate how much your using.

At the end of the day, it doesn't matter how much you claim to have, its how much your able to effectively use or how well you put to work what you only have.

That is the name of the game. I will take a "low" HP rating anyday to have a good usable MPH. Unfortunately once you completely understand what is going on, you need HP to make MPH. As more post, you will see however that you can have high HP numbers and not even come close to the respective MPH.

That statement may be confusing to some, but read it a few times and pay attention to the information being posted - it will become more clear.

 

322 rwhp 335 rwtq
3400 lbs 86 vette
3.07 gears
12.68 @ 108
Randy,

 

My old set-up was a 383 superram/219 motor.... my last dyno a few years ago showed 330 rwhp.... the next day I went and ran 11.55 @ 117 mph with a 1.52 60 ft..... go figure.

(however, best dyno was 362 rwhp, but that was a year earlier)

 

mine's a very close to stock 93 LT-1 zf6:
268.4 corrected RWHP (304ish ftlbs)
13.621 @103.45 mph
that was at Nathan's favorite track.

 

You have to consider the purpose of the car as well. Suspension, will all play a part in the 1/4 mile. A car that does well on a road course can do lowsy on a drag strip. In either case a well set up low horsepower car and outrun a poorly setup high horsepower car.

Jesse's biggest argument always seems to be that people with high horsepower numbers don't seem to run the track times that they "should." At that though you have to determine how what a car "should" run was determined. Is what a car "should" run based off of a car with sticky tires, a loose stall, shoft shocks in the back, etc, etc. Horsepower is only part of the story, the combination has to be optimized to apply that power in an effective manner for the intended purpose.

The only way that you can really get a good correlation between HP and track times is if you can hold all of the track conditions and car conditions constant. Vette's aren't F-bodies. Although they both may make the same horsepower, they can have radically different track times simply because they have different drivetrains, weight characteristics, drag coefficients, etc, etc, etc.

Jesse always tells us that people get too hung up on dyno numbers, and that dyno numbers don't always mean faster track times. He's absolutely right in that regard. However, a more powerful (referring to total power under a dyno power cureve) car, makes more power. That says nothing about if that power can effectively be utilized for one application or another. It simply depends on what your goal is. Do you want an extremely powerful street car that handles like it's on rails and has a crazy top end speed or do you want a mushy suspension drag car that uses every last drop of it's power to accelerate from 0 to a quarter mile and then do nothing else?

Neither answer is "wrong," but it leads to a bunch of argument that really just needs to stop. It never goes anywhere because both sides are "correct" provided you stick with the restrictions that each side presents. The issue in this argument always comes in when one side decides to ignore the restrictions that the other side places.

 

Actually all Jesse (and me too) was saying to a few forum members "is to be careful before you go and spend a bunch of money trying to fix a problem that doesn't exist and was simply a dyno variation"..... as far as I know, he wasn't really trying to convey anything else, besides the simple message "If the dyno shows you're down on power... you might want to verify the power is not their by running on the track once or twice.... thus the trap speed will indicate if you're close to the power the known set-up should make".

At least thats all I ever meant.... dyno's are fun and in many, many cases very accurate.... but not always.

cheers,
Beach Bum

 

You're talking about one particular arguement with Jesse, I'm referring to the more general case. We've been round in circles about these issues from every possible angle and it's completely pointless.

 

355CI was 342 RWHP 381 RWTQ = 11.81 at 114.8 MPH

406 is 405 RWHP and 437 RWTQ = 11.18 at 121 MPH

 

with mph in the 1/4 you can get a feel if your car is making good power, unless the car is over geared
Randy