turbostreetfighter

PeeJay, we agree on something INERTIA DYNO'S SUCK!!! i owned the third one in texas and sold it after fighting it for a year and a half!!!! they are very innacurate especially on turbo cars and high stall convertors. i have taken cars that made 800 h.p. on an engine dyno and on the dynojunk....jet.. would on ly make 400 to the wheels!!

MWW

SPOautos

But did thier track times represent a 400rwhp car or a 800bhp car???

STEPHEN

turbostreetfighter

the car went 9.50 @147 mph!! so i would say closer to the 800bhp !!


MWW

MIKE-P-28

iTrader: (1)

Wow good job guys on the works of physics

SPOautos

So what was causing the prob? Was it a combination of parts that made it read wrong or what it the dyno settings and the it was setup or what.

I mean there are tons of people that run on dynos and get results that are in line with thier reading. What cause this cars to be so off???

Maybe the dyno was defective

STEPHEN

rotarygod

iTrader: (1)

Not here to debate whether or not a light flywheel is better/worse or whether a certain dyno sucks or not. All I am going to say is that turbostreetfighter is the WRONG person to argue with about drag racing and what parts affect times and horsepower. He has been doing it since before many people on this forum have been old enough to drive. He was the first person to get an Integra to the 11's and he did that before anyone even heard of a fast fwd car. He is truly an innovator and is one of the only people I know who can actually make their own parts or invent a new one.

fdracer

pj,
wouldn't foot-pounds and pound-feet both be correct? since torque is the multiple of the lever arm length and perpendicular force, it doesn't matter how the units are ordered. it's multiplied so the order doesn't matter.

fdracer

marcus has a good point, but there are people that have run much quicker than him, and they swear by the lwfw. these are 4 cyl. motors too, which make very little low end torque like marcus's rotary.

peejay

Grammatically speaking, there's only one way to say it. Why it's opposite of the way it's abbreviated is beyond me. I hear what you're saying, really it doesn't matter... but there's a fine line between just getting the point across, and speaking properly.

turbostreetfighter: I've heard they have load-cell dynos that you can program in a "load curve" so that you can simulate the load your car would put on the engine for a given gear. That I think would be ideal, since you could accurately tell how quickly the engine can accelerate under the actual loads it will see instead of a generic one-size-fits-all drum like a Dynojet.

twint78

dictionary meaning of torque:twisting force

horsepower:we already know this

torque in terms relating to an engine is different which not much ppl do not know this.

torque has to deal with combustion cycle made by moving parts or twisting force.

backpressure also help to get it downlow.

to move out to a lightweight flywheel will not make lower torque numbers.a ligthweight flw accelerates and deaccelerates quicker.u can get to ur power quicker and mroe rapidly.

like pj said.u hafta match the gearing to go along with this.which must most ppl lack to do.the gears in ur car were made for that flw for a reason.if u have a tall gear the lfw has to spin more to get all aspects of the gearing.

it is kinda like pulleys.ur alternator pulley has to be twice as fast as the maindrive.if u put a pulley on ur alt the same size as ur maindrive then u produce less amperage.

basically move to a shorter gearing and u will see the torque is still there.

peejay

Absolutely wrong.

Optimizing the engine to be most efficient at lower RPM shifts the troque curve to make the engine "torquier". This tends to be restrictive at high RPM; after all the engine is not going to be efficient up there. "Backpressure" has nothing to do with it - no engine likes backpressure.

twint78

no engine huh?

well i work with crotch rockets alot.and guess what we do with exhuast systems to get a good torque rating?

we put specific bends in specific places to make the torque shoot up.

and what is it caused from backpressure.

as where other engine that are given straight exhuast are lowered.

turbostreetfighter

Fdracer...marcus has a good point, but there are people that have run much quicker than him, and they swear by the lwfw. these are 4 cyl. motors too, which make very little low end torque like marcus's rotary.


FD racer, just because my personal car does not run that fast (yet!!!!) does not mean that i am only involved with imports. on a daily basis i am tuning 1800 h.p. domestic turbo charged cars that run into the deep sevens and high six's.( quicker than ANY import right now) it just so happens that my passion is rotary imports. the information i am telling you guys is from my experiences, i am not trying to prove anything. and as far as you statement about the 4cyl FWD cars , as i said previously a LFW "softens the blow" and the works great on FWD cars. it is obvious that you dont understand what i am trying to say and the point i am making but if you keep thinking about it it will "click". another thing that you need to think about is the RPM's these hondas are turning ...11,000 so what do you think happens when a 10# FW turns 11k rpms? well..you get about the same rotating mass as a 15# FW at 7k rpms . the hondas are launching at enough RPMs to not bog but also give enough inertia to get the turbo going. it is a delicate art but when you have 11k's of rpms to play with things get easier.


SP auto....So what was causing the prob? Was it a combination of parts that made it read wrong or what it the dyno settings and the it was setup or what.

I mean there are tons of people that run on dynos and get results that are in line with thier reading. What cause this cars to be so off???

Maybe the dyno was defective

STEPHEN

the dyno was not defective, but you cannot duplicate REAL load on an inertia dyno and since TC's work directly off of torque multpication, a correct reading is impossible. for instance on the Quickest "F" body in the nation ( which i tuned last year) the car weighed 3700 lbs and ran consistent 9.18 at over 155 MPh!! on the dyno it would only make 650h.p. so what we did was have a special "lock up convertor" that locked the stator allowing no stall but would give a closer to real reading. after we installed the convertor the car made 978 RWHP and 1180 ft lbs of torque which was definately closer to what the car was making. so do you get what i am saying?

turbostreetfighter

Peejay...no engine likes backpressure???? are you nuts? i also play with crotch rockets and Twin78 is right, if no engine likes backpressure why do people use headers? not to be disrespectful man but i think you have been reading too many books and not enough track time, we are opposite in that what you know in formula's i know in reality and reality always wins because it is....REALITY!!! i am going to say this one more time: a LFW will accelerate the ENGINE faster but what good is that if you are not creating the gases to propel the turbo? ok lets break it down like this: PeeJay take two identical motors, one with a 30lb FW and one with a 5 lb FW. yes of course the 5# will accelerate quicker but which one will create more exhuast velocity trying to accelerate? the 30# will. and what does a turbo use to accelerate? do you understand now? you have to make the SYSTEM work


MWW

SPOautos

Yea, I pretty much understand what your saying its just that I'm not sure why. In that particular case was the main prob that the dyno didnt creat anough load to make the converter lock?

I guess its just wierd cause i've never heard anyone talk about this much in the rx7 world. Most everyone I know getting dyno numbers runs pretty close to in line with thier track numbers.

Am I missing what your saying or something?

Maybe I just dont understand the science of how a dyno like a dynojet works. I mean I know it read tq and converts it to hp via the formula but is the problem in the way it reads the tq??? Tq is the lbs of turning force so is the dyno figuring out the tq wrong or soething?

I guess I'm just wanting to know what it is about the dyno that cause it to not read tq right and how the load affects that.

If its to much to explain thats fine, I'm not a giant fan of dynos anyway.

Let me ask you this, if a dyno can read so low like in your example aboce is it possible for those short comings to make it read to high??? I mean whats up with some of these Supras reading 500+rwhp and running 11's or 12's....does it have anything to do with what we are talking about or is it possible???

STEPHEN

Evil Aviator

It's not abbreviated differently; you are abbreviating it incorrectly.

lbs-ft are the units for Torque

ft-lbs are the units for Work or Energy

It's OK, most people (even I) use terms incorrectly (like shocks & struts, etc.), but I think that everyone still knows what you are talking about, and some people would just get more confused with the correct units. Hehehe, once I asked a sergeant for some metallic cartridges and he looked at me like I was on crack, so I asked for some bullets instead.

E6KT2

Perhaps you could explain why an engine would need backpressure. Really, an engine does not need backpressure. I think that what really happens is that a cam is sized incorrectly or there is something going on with the pressure waves. A car/bike with a properly tuned exhaust can make more power than one without, but that is a function of pressure waves rather than backpressure.

turbostreetfighter

Let me ask you this, if a dyno can read so low like in your example aboce is it possible for those short comings to make it read to high??? I mean whats up with some of these Supras reading 500+rwhp and running 11's or 12's....does it have anything to do with what we are talking about or is it possible???

STEPHEN

yeah sorda..umm i guess!!! have you ever ridden in a 700RWHP Supra? if you have you would note that their powerband is super short ) like 1500/2000 rpms anything out of that range is dead and for that reason that go nowhere until the top of third gear and anything after that HOLD ON. anything below 100 mph the RX will slaughter them!! a way to somewhat 'trick ' an inertia dyno is to use an oversize turbine housing so that the turbo does not spool until way late and your reading will go higher, but try to drive it on the street and you cannot stand it!
dynojunks read higher than Eddie current dynos which are the way to go and are more accurate. the dynojunks usually give aout 8/12% higher reading than the Eddie current type. the EC dyno can load for the exact weight of the car instead of the standard 2980lb drum on a DJ. how can one drum be the same for all cars?


e6kt) Perhaps you could explain why an engine would need backpressure. Really, an engine does not need backpressure. I think that what really happens is that a cam is sized incorrectly or there is something going on with the pressure waves. A car/bike with a properly tuned exhaust can make more power than one without, but that is a function of pressure waves rather than backpressure.

your right an engine does not need backpressure to just run but to make power in a NA environment back pressure is needed to make power and torque ! pressure waves create backpressure , so you have answered your own question, have you heard of 'scavenge headers? they use the pressure waves to make backpressure without restriction.
now in a turbo situation NO BACKPRESSURE works the best ...point blank!!!


MWW

fdracer

marcus,
look dick, i've said all along you had a good point about heavier fw's. i understand about rotational intertia and i know adam used a heavier fw for that very reason. in fact i prefer a heavier fw on the street. what i'm trying to tell you is ************* these days don't ******* care about that and are running quicker than ever. now you're getting bitchy cause you have to keep backpedaling with more and more exceptions. read your first post, you praise how great the heavy fw is and how perfect it is for drag. then i ask some questions and now you have to qualify everything you said. now you say a lwfw is good if you have the proper gearing, it's good if you have too much torque, it's good if you redline at a high rpm. there's so many exceptions to your rule, now a heavy fw is good in only a few specific applications. i don't understand your ****** superiority complex, you think you know more than everyone else cause you've got all this experience this and experience that. well i'm sorry i don't have as much money as you to be a bigshot, i'm sorry that everytime a throw a rod straight through the block it takes me little while to save up again. now, i'm not attacking you in any way and i understand you've got a very viable point of view, but i don't appreciate your ****** attitude. you need to realize that there's two sides to every story.

peejay

Backpressure (resistance to exhaust flow) should not be confused with tuned resonance. Why do engines use headers... that's simple, the headers are less restrictive than a simple log manifold and the tubes can be tuned in length so that a negative pressure wave can scavenge the combustion chamber before the exhaust port or valve closes. If you're overscavenging, backpressure can band-aid the problem but the true fix is readjusting the exhaust system.

I understand what you're saying about the turbo energy... that just goes to show that turbo choice is dependent on MANY variables and not just engine size and powerband required

twint78

umm like me and turbo are saying,watch motorcycle racing sometime//moto gp.

it shows how backpressure works.hell look at a ducati motorcycle on how the piping is created compared to jap bikes.

backpressure also helps turbos.not necessarily completely good.but some does for the simple fact it affects spool time.

peejay

Don't confuse resonance tuning and optimizing the gas velocity with backpressure.

If a 2" pipe works better than a 3" pipe, it's not because the 2" is more restrictive, it's because it keeps the velocity up.

NoRice

My experience with a lightweight flywheel, the RB 8.5lb

I felt better pull in first and second gear. However, the shop that installed the Flywheel/clutch smashed the TPS wiring harness, it took a long time to figure it out.

Anyway, I can't really say how it pulled in 3rd, 4th, or 5th immediately after the change, since it didn't run right for sometime.

However, just recently I have felt that it isn't pulling as hard to or past 100Mph as it did before.

The only things I know that have changed.

1. Flywheel and clutch (ACT street/strip)
2. Recently installed M2 Dual catback (immediately after getting the TPS harness problem fixed)
3. Due to #2, the boost now goes to 16/17lbs, before it was set in the PFC to 14lbs.

So, is this lack of power around 100Mph and above in my head? (About 4 months passed between the flywheel install and having the TPS fixed. Memory/butt dyno maybe failing me?)

Or, is it because of #3? More boost, is pushing the turbos out of their comfort range, causing too much heat and actually making less power?

Other?

Just a note, I really like the RB Flywheel. Going up the parking garage, I have to stay in 1st gear, or drive faster in 2nd, it has lost some driveability. It will buck if I don't keep the revs up, while going up the incline in the garage.

twint78

another example peejay, look at a dodge viper.the backpressure from the 5 into 1 collector.

an x-pipe.it makes torque by pushing exhuast pressure back to make things flow more evenly.

hell take a dam for instance too.the more backpressure from water it has the more energy it creates.if water is barely there and dwindling then it creates no power.

Jeff20B

iTrader: (13)

I think a dam uses the volume of water behind it to build pressure. I guess you could call it back pressure because it's pressure and it's back there. However, The Viper has a header that looks like it's tuned length as much as possible due to size restrictions of the chassis. How can anything push exhaust back to help it flow more evenly? Your thinking it takes advantage of backpressure the way you described it is just lame. No offense.

I thought this thread was about light flywheels?