Sean Collins

Ok then lets ask the question this way. what do you think the odds of your car making 700fwhp are ??? I can tell you that the mustangs are plenty accurate. Point in case.

Engine on DTS dynomometer no accesorries with electric water pump made 536hp 405tq

Put engine into vehicle ( stick shift) engine made 456hp 383tq with mechanic water pump and full accesories.

Vehicle runs 10.8 at 126mph.I would say there is far to much measurement there to dispute. I can post up miles of data that would show your RWHP estimator to be vastly inacrruate.It just doesn't take that much power to go that fast in a 3500lb car.

On the big converter thing with them showing low number on the dyno do a stick auto swap on any vehicle wtch the ET and MPH drop going to the auto. Swap back to a stick the MPH goes back up and so does the ET unless you dealing with a proshifted car.

Yes converters do cost power if you make 380 or so with a a4 big stall car on a mustang dyno expect to go 11.20-11.30 at 117-119 mph.I will dig up the RWHP vs et for F car charts if i can find them.

HaulinHawk

Good thread GATOR!!! I will be at BMP thurs 16th, shakedown runs.Lets ride.

Zombie

iTrader: (2)

Odds of me having 700HP at the flywheel?? 100% (if you go off the HP formula) 0% if you go off the dyno numbers. It takes 650hp to the wheels to get 3800lbs to acellerate to 130mph in 1320ft. I think I can say the drivetrain sucks up 50 hp. All comes down to how you want to measure it.

Don't confuse accuracy and consistancy. All dyno's i've tuned on have been consistant, dynojet and mustang. As for how accurate they are I don't know. I'd say both would be closer to accurate on stick shift cars.

FWIW I've watched a t56 4000lb car make 500 rwhp on this same mustang dyno. He ran 12.2 @ 119. Yet my 3800lb th400 car made 470 rwhp and went 10.5 @ 130. That is not very accurate if a 200lb lighter car with 30 less hp equates to 11mph difference in trap speed.

If someone wants to know how much power the car makes I just go off the calculated HP numbers. If they want to race, I tell them the dyno number The MPH you trap at the track really tells you what's going on. There is no substitute.

Dyno's are best used for tuning and troubleshooting, not getting HP numbers.

Sean Collins

Chassis Efficiency, Chassis Efficiency, Chassis Efficiency If the car is not setup it will not MPH or ET worth a crap. this accounts for 95% of the disparity i see in big power cars all the time. but like i siad if the chassis doens't work you can loose MPH like crazy.if you look at the 119 mph objectively if the car was efficient it would be going very mid low to low 11's fiarly easily i would say 11.35-11.25 would be inline with that MPH. I'd bet you fix the traction and other issues and the car would at least equal yours in performance.Secondly the HP output from mustangs is accurate. When we get the cars working properly chassis luanch etc our drag sims are within 1 tenth and 2 mph. Most folks just don't realize it doesn't take 700hp to run 10's in a moderately light vehicle. If you don;t believe me pull the engine and stick it on a DTS or similar trustworthy dynomoeter and id bet your only making 560ish at the flywheel.

Dynomometers good ones that can back up the numbers are very truthfull for hp.There are some things in those formulas that your using that are not accurate. the faster you go the less wieght becomes an issue and the more aerodynamics does. At around 95-110 mph your fighting air more then wieght.

BAIN

iTrader: (5)

Ok plug this into your formula and see what you come up with. 3240# and 121.30 mph.

Zombie

iTrader: (2)

Collins, are you saying that an unlocked converter makes absolutely no difference in a dyno number? Unlocked converters can and do make a huge difference in accurate numbers.

I put no faith in dyno's except for tuning, the unit of measurement means very little to me. What I don't understand is why people care so much about dyno numbers? Track numbers are what really matter.

Sean Collins

Locking the converter creates a giant lie. Unless you lock the converter all the way down the track its just more lies.

As for the dyno telling lies don't try to tell me a car that makes 280hp on the dyno is going to run 10.50's and conversly a 700hp car is going to run 14.50 unless of course something is horriably wrong.

The dyno can be a very accurate tool to diagnose what is wrong with an underperforming car. The problem is that there is a myth that dyno numbers don't mean squat which is straigth BS and those underperforming cars never get sorted becuase the mentality is that the dyno is irrelavant. The issue is you have to use a known quantity.In my case its the mustang 1750de dyno. I know how it comapres to ET and MPH at the track. We have found fixed and helped get many cars to run better at the track by using this tool. The dyno can ony tell you what the potential is its upto the customer and the shop to optimize the vehicle to get the best ET possiable.

Dan

iTrader: (1)

I think my car is about right..my best et is a 12.21@110mph..From looking at this board, I have one of the lowest MPH's for that ET..My car dynoed 334rwhp with the Vig 3600 and had a 1.66 60' on that run, No spin, hardly no gas, That's all she had..Since then I installed a SS4000, From the feel of it I think I can drop off another 1/10th So to sum it up Dyno Numbers don't tell everything but they do help...I would take ET as opposed to MPH any day of the week.

Sean Collins

110mph you should be marching to high 11's 11.99 would be about right. the 4000 stall will help just watch that you don't rev to far beyond the power band on the upshift. with a 4000stall you might want to shift the big mean machine at 5900 to get optimum performance depending on how much shift exstension you get out of it. Video tape the car going down the track. If it ever noses down you shifting to early or late. btw thats fiarly typicall of 335whp.

BAIN

iTrader: (5)

GregWS6&z28

iTrader: (8)

no you dont. i have run many 12.1-12.2's at 110mph. my 60 foots were the exact same. I see that alot with stalled cars vs manual. they will be a few MPH lower for the same given ET

Dan

iTrader: (1)

Yeah, you are one in how many on here running the same mph & ET as me? Check the 12sec timeslips & tell me how many are running our times with 110mph

import slayer

Scoggin Dickey

iTrader: (34)

You actually want to use 340rwhp/.85 = 400hp. Multiplying by 1.15 is NOT the same as dividing by .85, and since you're assuming 85% efficiency, dividing by .85 is the correct way to calculate this. Just my $.02, carry on

engineermike

An interesting anecdote to share:

My old combo with a T-trim Vortech on a 383 made 550 rwhp through an A3. My brother's mod'ed '03 Cobra made 503 rwhp through a stick. I ran 10.40 at 133 and he ran 12.20 at 117 mph. 47 hp difference, similar weight, and the result is 16 mph faster?

Also, this is an interesting thread:

http://www.turbomustangs.com/smf/ind...?topic=12123.0

222 rwhp loss from switching from a 6 speed to an A4!

Sean Collins

Same type of dyno for both cars ???

engineermike

Same exact dyno - at Thunder Racing.

Sean Collins

Can you post the dyno sheets please. I am going to show you the problem with using a dynojet to measure HP and TQ. for the Record a dynojet at 500hp read 16-17% higher then an equvilent Mustang and to boot the error get larger the more power you put to the dynojet.

Zombie

iTrader: (2)

Whats the reason for the 16mph difference in trap speed though, thats a huge difference. His results are similar to the ones I have seen that I posted about and mine were done on a mustang dyno.

Sean Collins

thats why i asked to see the dyno sheets.