9kNback

I was browsing the HopUp Racing site looking for a parts for my car and I came across the Unorthodox Racing Flywheel claiming horsepower gains of 10-30 at the wheels. I am wondering if these gains are realistic? If not what type of hp gains can be expected?
The link is http://www.hopupracing.com/unraflwiinco.html
Thanks, Ryan

cretinx

Flywheel doesn't give you horsepower

It lets you rev faster.

Charles R. Hill

iTrader: (7)

Expect to factor in about 2.7 h.p. for every pound removed from the total flywheel and clutch package. From what I have read the factory 8 has about 40 h.p. in driveline loss and I expected my loss to be cut down to about 25 h.p. when I installed a 9.75 lb. fly. I wasn't disappointed with my before and after results as measured by my G-Tech. As stated, a lighter flywheel doesn't add h.p. to the output of the engine. However, it does provide for a more efficient drivetrain. The real purpose of a particular flywheel weight used by the vehicle designers/engineers is to create a level of user-friendliness with regard to the friction window of the clutch. Some think that the weight of the flywheel has to do with the quality or nature of the drag strip launch but that is not really the case. The weight chosen is more for balancing the forgiving nature of a heavier flywheel against creating an efficient driveline. A lighter flywheel requires a higher level of finesse to properly use it and most gentlemen refuse to admit that their driving skills may not be on par with what a light fly requires for street use. These things require a little more concentration to manage and one better be a serious driver to use a very light flywheel in anything but the most aggressive situations.

CRH

cortc

It reduces parasitic loss, thus frees up HP... More to the wheels and yes you can measure it...

Richard Paul

iTrader: (5)

Ahh, not quite. It is not parasetic loss in the ame wy is say a water pump. It takes hp to get a given mass rotating. Once it is accelarating at a slow pace it takes little power from the overall drain. So in first, second and somewhat in third there will be some extra hp that can o someplace else. example to get te car moving instead of the flywheel. In the higher gears you will se very little gain if any.

So do you get better accel? yes. You will feel it in the lower gears. It is not an illusion it will help your et. Yet do not claim it adds hp/

Now as to the claims of some manufactuers they are bs. What gear did they get those readings? I promise you they didn't get them on an engine dyno. Ask them for a fourth gear read out.

Now cortc you seem to have numbers for pulleys. This is an area I would like to see the particulars on. The pulleys have less weight to loose and not the polar moment of a flywheel. If the numbers you are quoting for bolts and nuts so very close to the center line are real then the flywheel power gains are conservative. I shouldn't say that as I don't remember what they were, just that I thought them high.
You too failed to give which gear you used.
If you read these in your own tests I will believe you, just skeptic of manufactures. I don't include you in that as your just having fun as a hobby. Someone who is making 10 sets doesn't have to bs the world.


Charles, you can't make that statement without knowing where on the flywheel/clutch package the weight came from. If you take it from the outer ring it gives you more then if you took it from the hub. You can have two flywheels that weigh the same and have diffferent rotating properties.
And you too. What gear are you getting these readings in?

cortc

Richard,

What you are saying is true and we are really talking about the same thing... Light pulleys take less energy to spin up and the faster the rate of acceleration the larger the effect, so in the lower gears you will measure more apparent HP... Once the RPMs stabilize you will not see any difference in HP figures but then in this case we really just care about the affects on acceleration not the measured HP on an engine brake dyno...

Pulleys do help, and when added to other mods start to add up to changes you can measure in elapsed times...

shaunv74

There are many threads on light flywheels out here already where we flogg the subject pretty well so do some searching around. I have the Racing Beat Flywheel and like it. I posted a Gtech comparison between PoLaks car and mine, both in third gear and shows some good results. Around 2-5 hp is what it showed to the wheels.

Charles R. Hill

iTrader: (7)

C,mon Rich, we have discussed the polar moment of inertia and all of that crap in the past. My aims and interests are to not confuse or mystify the issue for those interested in the potential gains made by certain mods. My interest is in explaining the value of certain mods to others in a way that they can understand it and place reasonable expectations on the outcomes of said mods. I know the math on these things to the extent that I no longer need to worry about it. My h.p. calculations come from knowing the full weight of the vehicle and taking a few 1/4 mile passes with my G-Tech. Is this wholly scientific? Of course not. But then again, when racing on the street or track science accounts for only so much. Does a light fly show tangible benefits during its use? Hell yes!! Can I pass along a rule-of-thumb that allows others to reasonably predict the gains offered by these mods? Yes. My guess is that is the same thing that cortc is trying to do. I offer up as proof that I am not full of "it" when it comes to these discussions the idea that if one were to follow my history on this website my own stories and anecdotes will show that I predicted the e.t.'s I am now seeing. That's the difference between practical application and mere bench-racing.

BTW, Rich, you and I have had great coversations in the past and I have learned a great deal from you and your threads. Most of the time, though, others couldn't care less about the math involved in this stuff. They just want to know what to expect and how to go about getting the results that they read about in mags and hear from their friends. I want to help our fellow RXers beat those damned Evo's and STi's like I now do on a routine basis. I am looking forward to my turbo/nitrous combo so I can get their money. as well. Let's not turn others off to the idea of modding their 8 by over-intellectualizing the matter.

CRH

MadDog

Charles - well stated, as usual. Mad props, my man. Mad props.

Richard Paul

iTrader: (5)

Charles, I ment no disrespect, on the contrary, I have the utmost respect for the methotical way you mod your car and document it. Your a great asset to the forum, these guys are very lucky to have you work these things out and are willing to share. I seem to get to technical and loose most ears halfway through my soap box lecture.
You are a model member of any forum community. Now that I've said that, in my defence, I can't help myself.
I just can't help but forget that no one cares how it got that way, they just want to know it's there.

One day my great freind the late Dave Zeuschel was at my place for the afternoon and sat in my office through a few phone calls. When we went for dinner he said to me "why do you spend all that time telling everyone all that stuff? Just tell them to buy your supercharger and they will light the hides in the eyes."
He always was a man of great insight. Same thing as your lesson to me. Help me I can't help myself.

cretinx

you'll also have no traction in lower gears.

I ran slower times with a lightened flywheel than with the stock on on my Celica, simply because I couldn't hook up.

Charles R. Hill

iTrader: (7)

Rich, people who know what they are talking about are difficult to offend because they have a solid base for their information. Yours comes by way of intellect, mine comes by way of putting the foot to the floor and outrunning the cops good ol' fashioned redneck style. Of course, those were my younger days. Now I just race for the money. Like you, I tend to overexplain things sometimes and have seen my share of glazed-over eyeballs. That said, I consider myself lucky to have access to people like you who can give all of us a lesson on the intellectual nature of what we do. All that info works wonders when it comes to pickin' up the chicks. Love ya, Man.

CRH

p.s. Have you thought over my proposal for a hydro-drive?

ACTman

Good information. Sorry to see you get so much heat over it.

HP gains would appear on a dynojet because it is really measuring acceleration of the big drum, and calculating HP and torque. Now use a Mustang or other load bearing dyno and the results are much different. Would you see a hp gain with a lighter flywheel if the dyno is set to hold the rollers at one speed? I don't think so. I like to explain it another way: With a lighter flywheel you have less power in storage (in the form of flywheel inertia) and more power for acceleration. A heavier flywheel is useful for not only making the vehicle easier to drive, but it also helps dampen out torsional vibrations that tend to wear out other parts. A lighter flywheel is a lot more fun though! A lighter flywheel doen't = more HP.

Charles R. Hill

iTrader: (7)

ACTman, the heat Rich received was from a long-time board associate who he knows was delivereing the heat "tongue-in-cheek" and I am sure he took no offense from it. In addition, all of your information has already been discussed with the same detail and same conclusion(s), so thanks for the validation. I think the conversation about the scientific aspects of varying flywheel weights has run its course but we need to have more discussion on the personal experiences of installing light flys to benefit those less interested in the science and more interested in getting help deciding which one is right for them. That was the point of my post.

CRH