OK...So what is the "FBI" & what is the FBI 500????

[alnukem]

I don't know the answer, but I'm sure it's going be a trip!

[LGAFF]

FBI is just a reference to the large # of Zs and guys that do ZR-1 mods in the Chicago Area/IL.....Fast Boys of Illinois.....FBI..

[RICKYRJ1]

FBI 500 is a reference to their engine performance modifications (500HP) I beleive the number is really a bit higher :-D The FBI is always looking to push the LT5 to even great heights of performance. A lot of R&D comes out of their garages. They are a great asset to our community. :saluting:

[alnukem]

So, Are the FBI 500 mods secret????? I was reading around here & someone alluded to some porting "nuances", is this part of it?

[Paul Workman]

So, Are the FBI 500 mods secret????? I was reading around here & someone alluded to some porting "nuances", is this part of it?

The "500" package you mention refers primarily to the almost stock-bottom 350 block in combination with a set of basic porting paterns initially laid out by published model performance predictions produced by various flow dynamics tools.

But, it doesn't end there. Research and a healthy amount of experimentation guided by substantial practical expertise coming from certain FBI individuals having decades of racing - all blended together in a tight knit group that has been pushing the envelope of the LT5 for over a decade now.

Is there room for improvement to "the package?" Yes, and the process continues. For example, Marc Haibeck's recent announcement that his 500 package, due to some recently prooved nuances of his porting, is now pegged at 510 hp, and still produced from a stock-bottom 350 LT5 using stock cams!

Is there something that distinguishes an FBI 500 package from another? I think in a general sense - most definately! In a nut-shell, it would be "drivability" is one thing that stands out. In other words, the FBI built and tuned motors not only produce the power, but also defy the loss of low and mid-range performance that is often spoken of when it comes to porting (especially) mods. And why is that? Part of the answer comes from the fact the cams can be independantly timed; much effort has been expended on refining the cam timing issue - according to what produces not only hp gains, but retains low and mid range torque as well. And, part of the answer is knowing where to port, and where to stop (which extends to cam profiles, etc, as well.)

Are the paterns developed or is the technology vastly different from what others might develop? Perhaps not. (There is even a CNC program off of Pete's heads that is avaliable from Pete.) But, the LT5 is NOT an easy or cheap motor for the individual to experiment with. And, since the cost in time and money to develop the supurb package aka "FBI 500" package was largely at their own expense, you could hardly fault a Marc or Pete or Bob or Al or Kevin or Lee for holding some of their hard - won "nuances" to their collective chests. So, the answer to the "nuance" question is yes! The devil is in the details;)

Wanna talk about big inch FBI LT5s?? There inlies some truly inovative work going far beyond what some of the big names accomplished in the early days.

P.

[Pete]

The 350ci/500 would not be possible today if it wasn't for the FBI.
Today most tuners offer/have a 350ci/500 package.
Some of the info was given away some was stolen this is the reason for secrecy.
Before this one had to spend a lot of money to get 500hp package and go with a bigger motor (368ci)
Today a 368 is not worth, money vs gains.

A lot of money and time went into the research.
This was very risky research it would've been hi cost monentary wise if it didn't work since LT5 parts are very pricey.

Pete

[Blue Flame Restorations]

Well, my hat's certainly off to the FBI gang. Pete, in particular, since he provided me with 500+ horses and the most fun Corvette that I've ever owned, and I've owned over forty of them. And I've had the pleasure of driving them all, from 6 clyinder 53's to big blocks. My ZR-1 is the best of any of them.

Thanks, Pete!...and everyone else in FBI land!

[XfireZ51]

Well, my hat's certainly off to the FBI gang. Pete, in particular, since he provided me with 500+ horses and the most fun Corvette that I've ever owned, and I've owned over forty of them. And I've had the pleasure of driving them all, from 6 clyinder 53's to big blocks. My ZR-1 is the best of any of them.

Thanks, Pete!...and everyone else in FBI land!

Brett,

Well said!

[Fully Vetted]

Well, my hat's certainly off to the FBI gang. Pete, in particular, since he provided me with 500+ horses and the most fun Corvette that I've ever owned...

Thanks, Pete!...and everyone else in FBI land!


Amen, brother! I can also attest to Pete's work. I bought Michael Christians' '94 Blue Beast with the FBI "500 Package" (which, BTW, ended up being well over 500 HP) and it is scary as hell when you leave your foot in it yet as tame as a Camry when tooling around town. I wish "Freak of Nature" could fit on a license plate!

Hopefully, I can meet you guys at Carlisle or BG next year.

David

[Fully Vetted]

And, since the cost in time and money to develop the supurb package aka "FBI 500" package was largely at their own expense, you could hardly fault a Marc or Pete or Bob or Al or Kevin or Lee for holding some of their hard - won "nuances" to their collective chests. So, the answer to the "nuance" question is yes! The devil is in the details;)

Wanna talk about big inch FBI LT5s?? There inlies some truly inovative work going far beyond what some of the big names accomplished in the early days.

P.


So, for us newbies, who is the core group that is here on this forum and what are your screen names so we know who we are talking to and recognize you on threads? I know a few but not all...

[alnukem]

You guys are very fortunate to have so many people, so close. It's kinda amazing how many ZR-1's are there in the heartland! I have always been amazed at how powerful our cars can be with the stock cams. I knew you guys were pushing the limit of LT5 performance & when searching, it seems you guys have some awesome comradery....that's great!!!!

[BigJohn]

My Callaway supernatural 490 is 350ci and 500+hp.
:cheers:

[FU]

OK...So what is the "FBI" & what is the FBI 500????


Your going to have to spend some "time" with Pete the Greek for that answer !

[Paul Workman]

So, for us newbies, who is the core group that is here on this forum and what are your screen names so we know who we are talking to and recognize you on threads? I know a few but not all...

Not the entire group, including yours truly that took the photo, but the "usual group of suspects" that came to eat pizza and to celibrate winning the team trophy at a local Corvette shootout...

http://i185.photobucket.com/albums/x220/6PPC_bucket/Trophy.jpg

[FU]

Notice Pete is the only guy who's hand's aren't on the table ?

[Pete]

Notice Pete is the only guy who's hand's aren't on the table ?


My hands are always busy,that's why my wife married me LMAO.

Pete

[XfireZ51]

Paul,

Here's a picture taken at the 2011 Shootout with participants there

http://www.crownpointvettes.org/pb/wp_123093eb/wp_123093eb.html

or here:

http://i187.photobucket.com/albums/x198/Z51Xfire/untitled.jpg

[WB9MCW]

http://i126.photobucket.com/albums/p110/HAMMERHATE/FBITEAM-1.jpg

[Meanmyz]

I have always loved the yellow ZR-1 picture in the 1994 Corvette brochure. This banner is exactly what I would like to see on our next Net Registry T-shirt!!! Can I say this again? My vote for the next shirt!!!

On subject, I cant wait until I can get the 350 500hp package. And yes, my car will be headed to Chicago!!!

http://i126.photobucket.com/albums/p110/HAMMERHATE/FBITEAM-1.jpg

[-=Jeff=-]

I have always loved the yellow ZR-1 picture in the 1994 Corvette brochure. This banner is exactly what I would like to see on our next Net Registry T-shirt!!! Can I say this again? My vote for the next shirt!!!

On subject, I cant wait until I can get the 350 500hp package. And yes, my car will be headed to Chicago!!!

Let us know when you will be here and we can try to schedule a pizza gathering too

[cvette98pacecar]

Let us know when you will be here and we can try to schedule a pizza gathering too

I have to take my Grandchildren Christmas Shopping, I will be in Chicago Dec 28th weekend. I would be more than happy to meet everyone for a good piece of pie.

[Hib Halverson]

The 350ci/500 would not be possible today if it wasn't for the FBI. (snip)

Pete

I respect the business FBI has today, but the above is statement is nothing but a crock of BS.

The 350 in my 95, when it was built in 1997, made 413-hp at the wheels SAE-corrected which, with the 18% C4 manual driveline loss, maths to about 503-hp at the flywheel. The engine has stock cams, VanDeventer heads, cleaned-up stock manifolds, cats, a Z-Industries cal and a custom-build exhaust which uses Flowmaster mufflers.

And yeah...the drivability is there, too.

Automasters built that motor 15 years ago...when "FBI" didn't even exist.

Hell DRM was building 475-hp 350s 20 years ago.

[LGAFF]

I believe that is referring to the head work Pete came up with that moved the cars the next level...Pete's 350 has 470+ rwhp....not sure others have matched that

[LGAFF]

I will say that Pete has done alot of expensive/extensive research.....funniest thing I came across is the fact that Petes cam profiles(done with his own research) are nearly the exact profile that my cams have, and those cams were designed by a group of engineers and cam experts back in the 90s....same guys that made one of the fastest cars in the world.

Pete uses the same practical "engineering" that the folks at Mercury used....based upon experience and not following the "rules"

[Pete]

If one is racing dyno sheets you can shoot out any HP #'s.
The question is can they back them up?

I guess i should've said 550hp
If 413 RWHP is 513 crank then what's 435-440 rwhp?

435-450 rwhp is the norm today for a 350ci these #'s were achieved with 368ci back in the day.
So your saying is all the guys who make 435-450 rwhp and back it up with a 350 ci LT5 are all BS.

This is getting a bit tiresome and old.
Flip me over,i'm done.
Pete

[Blue Flame Restorations]

You can lead a horse to water...but if he thinks he already knows everything there is to know about water.................

[Paul Workman]

I respect the business FBI has today, but the above is statement is nothing but a crock of BS.

The 350 in my 95, when it was built in 1997, made 413-hp at the wheels SAE-corrected which, with the 18% C4 manual driveline loss, maths to about 503-hp at the flywheel. If you use the more common, 15% number, it makes 513-hp at the flywheel. The engine has stock cams, VanDeventer heads, cleaned-up stock manifolds, cats, a Z-Industries cal and a custom-build exhaust which uses Flowmaster mufflers.

And yeah...the drivability is there, too.

Automasters built that motor 15 years ago...when "FBI" didn't even exist.

Hell DRM was building 475-hp 350s 20 years ago.

Hib,

First of all, if you're gonna cry "crock of BS", you should at least have your math right...

413/.82 (18% drivetrain loss) = 503+ chp

However,

413/.85 (15%** drivetrain loss) = aprox 486 chp, not 513

So, it would appear your numbers from days of old are LOW (aka NOT the state of the art, is plain to see), which marginalizes your supposition that somehow "others" got there first and Pete's comment may (in fact) stand after all!

Current FBI performance levels didn't happen all at once. There was and continues to be considerable trial and error involved - constant pushing of the envelope. And, if you think the epitomy was reached by Automasters or VDV or Rippie some 20 years ago, I invite you to check your math and have a discussion with those owners that had their rides initially done some 20 years ago and since modified by Marc or Pete or Lee or Bob and get their opinion of where the state of the art is NOW.

Driving a new stake in the ground...

Pete is now at a documented 474 rwhp on a stock bottom 350 with cams and continues to push the envelope. Marc now advertises a 510 hp package, based on the 15% inertia losses. Pete's saying "if it weren't for the FBI, there wouldn't be a 500 package", I believe means when others left off, he and others have continued to push and push and push the na LT5 with ever improving results. But, soon as one of these monsters gets into the puplic and changed hands once or twice, anyone with a snap gauge and a degree wheel can build a copy (and have!) is Pete's point. LOTS of copying has been done. Others now building 500 packages may well be standing on shoulders of Pete, Marc, Bob G, Lee, to name a few.

Time slips talk and BS walks. Care to bring your "513" hp 95 to a dyno or a drag strip and run it against my little ol' 508 hp FBI? See you at BG next spring???

P.

[BigJohn]

Everyone please re-do your math!!!
It is giving me a headache!!!
:cheers:

[WB9MCW]

http://i126.photobucket.com/albums/p110/HAMMERHATE/fuzzymath.jpg

[Kevin]

i've never believed that hp loss is a %, it has to be a fixed number. the tranny doesn't use more HP just because there is more available.

[Kevin]

Kevin.....The tranny may see constant internal resistance Torque (your intuition is correct) but the rotational speed (rpm) on input and output changes. Power equals Angular Velocity multiplied by Torque. So as Angular Velocity increases, so does loss of power through the transmission if the internal resistance Torque within the transmission is constant as you are intuitively thinking ;)

That is my intuition with just a tad of Engineering/Farming Background :D

LT5/ZR-1 Technical Calculations (http://forums.corvetteforum.com/c4-zr-1-discussion/3117790-tech-info-lt5-zr-1-technical-calculations.html#post1581660565)

too many numbers, I give up

[Hog]

i've never believed that hp loss is a %, it has to be a fixed number. the tranny doesn't use more HP just because there is more available.

Its not a fixed number, the more power that is applied will result in more power being lost. From the crank to the tires, every single surface that rubs on another is forced together harder with more power applied to it.

If you engine dyno at 300hp then chassis dyno at 250, you have lost 50hp to parasitic losses. Now take an engine that engine dynos at 800hp, install that engine in the same chassis, you surely are not going to get 750 rwhp.

I am not a fan of calculating rwhp into engine hp for the purposes of being compared to other engines. Engine power should ideally be derived from an engine dyno. But I do understand the practice of calculating engine power from chassis dyno power for the sake of simplicity.(not having to pull and engine to measure power).
Chassis dyno numbers are only comparable if the same dyno is used. Way too many variables otherwise.

peace
Hog

[BigJohn]

Its not a fixed number, the more power that is applied will result in more power being lost. From the crank to the tires, every single surface that rubs on another is forced together harder with more power applied to it.

If you engine dyno at 300hp then chassis dyno at 250, you have lost 50hp to parasitic losses. Now take an engine that engine dynos at 800hp, install that engine in the same chassis, you surely are not going to get 750 rwhp.

I am not a fan of calculating rwhp into engine hp for the purposes of being compared to other engines. Engine power should ideally be derived from an engine dyno. But I do understand the practice of calculating engine power from chassis dyno power for the sake of simplicity.(not having to pull and engine to measure power).
Chassis dyno numbers are only comparable if the same dyno is used. Way too many variables otherwise.

peace
Hog

Now I like your answer!!!

[FU]

Now I like your answer!!!

That's because it is the correct answer.

[mike100]

I tend to believe it is more rpm related as friction will increase with gearing changes or how fast your ring and pinion is frothing through the gear lube or your u-joints are spinning, etc etc...

I would like to understand how applying more torque (lets say double) at a given speed will increase losses.

Then don't forget about pumping losses and that kind of stuff, but if a drivetrain on a 300 hp car uses 60 hp parasitic at 6000 rpm, then I don't see it being much different for a 350 hp engine at the same 6000 rpm (lets say for a larger displacement in the same car).

It may be a straight 15-18% for typical engines in the 200-400 hp range, but get outside of that range and I wonder how true that rule of thumb still is. Hence my question about doubling the torque- I don't think it increases the loss in proportion to the torque increase.

[Paul Workman]

I agree w/ the notion that projecting chp from rwhp is frought with tripwires. I've never thought that the converson between rwhp and chp was particularily clean. Case in point: Just a couple critical physical factors in the mix include friction, and perhaps more important, inertia of the rotating mass.

The inertia of all the rotating parts: The higher the rate of rotaional accelleration, the greater the % difference between crank and rwhp values: i.e., it takes energy to bring the drive line rotating mass up to speed. This can be clearly seen by the apparent 15 (or so) rwhp improvement measured when simply switching from the standard dual mass FW to a 13# single mass Fidanza. Inertia...

And as mentioned, FRICTION. Is friction in the drive train exponential or more or less linear?? One of our real mech engineers around here might be able to be specific. That said, I too have my doubts when it comes to applying any specific drive line losses when the difference between various motors can be worlds apart, in terms of rpm and torque charicteristics. Are the drive line losses the same for All clutch hp values, or just a "rule of thumb" for motors operating within a range of output. (Someone has to know!)

Must be winter comin' on? Otherwise we'd be drivin the snot outta our Zs instead of this winter pass-time of second guessing and bench racing, huh?

P.

[Dynomite]

I agree w/ the notion that projecting chp from rwhp is frought with tripwires. I've never thought that the converson between rwhp and chp was particularily clean. Case in point: Just a couple critical physical factors in the mix include friction, and perhaps more important, inertia of the rotating mass Only when changing angular velocity.


The inertia of all the rotating parts: The higher the rate of rotaional accelleration, the greater the % difference between crank and rwhp values: i.e., it takes energy to bring the drive line rotating mass up to speed. This can be clearly seen by the apparent 15 (or so) rwhp improvement measured when simply switching from the standard dual mass FW to a 13# single mass Fidanzy. Inertia...Some inertia calculations for you Tech Info - L98 Frisbee Horsepower (http://forums.corvetteforum.com/c4-zr-1-discussion/3117790-tech-info-lt5-zr-1-technical-calculations.html#post1581660586)

And as mentioned, FRICTION. Is friction in the drive train exponential or more or less linear?? One of our real mech engineers What a dilemma....not only is Inertia and FRICTION elusive....determining who are the real mech engineers is even more elusive :D around here might be able to be specific. That said, I too have my doubts when it comes to applying any specific drive line losses when the difference between various motors can be worlds apart, in terms of rpm and torque charicteristics. Are the drive line losses the same for All clutch hp values, or just a "rule of thumb" for motors operating within a range of output. (Someone has to know!)

Must be winter comin' on? Otherwise we'd be drivin the snot outta our Zs instead of this winter pass-time of second guessing and bench racing, huh?

P.

Oh...Boy :D

Paul.....I am getting another Z...this time a 90' which I will leave stock except Headers....and and...Oh...here we go again :dancing

Since you did not get around to tell me the specific differences between a 90' ZR-1 and a 91' ZR-1, I had to just buy a 90' ZR-1 to make the side by side determinations myself.

Glad to see you back in the thick of things Paul......always enjoy your posts :thumbsup:

While efficiencies of transmisison may depend on many variables and may be variable depending on loads, we really only have one load of interest. That is Maximum load the engine can produce. I say transmission vice transmissions since the transmission of load involves the transmission, universal joints, differential, more universal joints, tire rolling resistance if you are measuring the power output where the tire meets the pavement. The efficiency in the transmisison also depends on the oil viscosity and associated lubricity and gear ratios (you might achieve the overall same gear ratio by adjusting the transmisison and differential gear ratios ending with the same result but different efficiencies in each).

Spin the output of transmission faster and output of differential slower for same end result with fixed engine rpm and same wheel rpm for example.

So if we just confine the debate to Maximum Power Output for determinations of Maximum Speed and Maximum Torque for example the discussion is much simpler ;)

A resistance torque of the transmission for example can be converted to HP loss depending on the input rpm (resistance torque is on input shaft).

So not to get wrapped around the axle pun intended we should use the math to make estimates short of a run on the Dyno (not Dynomite). There do exist nice rules of thumb for the conduct of those estimates some of which were produced by actual dyno runs.

This post will self distruct in 12 hours :D

Cliff

[Pete]

Somebody explain this.

A members big inch LT5 on a engine dyno made 700hp
On a chassis DynoJet it made 640 rwhp.


Pete

[Dynomite]

Somebody explain this.

A members big inch LT5 on a engine dyno made 700hp
On a chassis DynoJet it made 640 rwhp.

Pete

640/700 = 91% transmisison of power to rws. 9% loss of power in the transmission of that power :D The transmission, drive line, differential, rubber used 60 hp which turned to heat and was dissipated by air cooling of wheels, differential, drive line, transmission. :cheers:

If you could capture that heat dissipated and run it back into your car you could drive your Z in the winter in Chicago without using hot engine coolant to heat the inside of your car.....;)

So...what is a DynoJet? :D

[Pete]

640/700 = 91% transmisison of power to rws. 9% loss of power in the transmission of that power :D The transmission, drive line, differential, rubber used 60 hp which turned to heat and was dissipated by air cooling of wheels, differential, drive line, transmission. :cheers:

If you could capture that heat dissipated and run it back into your car you could drive your Z in the winter in Chicago without using hot engine coolant to heat the inside of your car.....;)

So...what is a DynoJet? :D


So your saying 9% loss is correct and would this be for every LT5.

I'm also thinking it's a constant #.
I can't see a 1000 hp car needs 180 hp to spin trans/diff same car made 180chp before
mods so how was this car moving/drive.
So 180 chp needs 30hp to spin trans/diff but when i mod it now it needs 180hp something does not make sense.
New C6 ZO6 rated 505chp most make around 450rwhp +-10
New ZR1 638chp most make 560rwhp+- more loss for supercharger

Pete

[mike100]

I honestly believe that the C4 manual drivetrain only uses 60-70 hp (at LT5 rpm ranges). I'm not surprised by the big inch LT5 results at all.

And to comment on Paul's explanation, there exists the intangible properties of engine designs willing to change speed rapidly that is not easily shown on dyno plots, but rather track performance or reputation that a certain car is 'fun to drive'.

[BigJohn]

If you turn your LT5 90 degrees and your wheel turned the same rotational direction as your engine your hp loss would be less.
:cheers:

[QB93Z]

I have a really basic question about comparing Crank HP to Rear Wheel HP.

I believe that an engine dyno measures the power output of an engine on a test stand. The engine is run at a constant, optimum rpm and a machine applies load to the crank shaft and measures the power produced.

I believe that a "Dyno" is a calibrated mass that the car's rear wheels spin as the engine is accelerated for low rpm to max rpm. A computer measures the rate of acceleration of the rotating mass and calculates rear wheel torque and then does mathmatical formula to determine horse power.

Is my understanding correct? Thanks.

Jim

[Dynomite]

I have a really basic question about comparing Crank HP to Rear Wheel HP.

I believe that an engine dyno measures the power output of an engine on a test stand. The engine is run at a constant, optimum rpm and a machine applies load to the crank shaft and measures the power produced.

I believe that a "Dyno" is a calibrated mass that the car's rear wheels spin as the engine is accelerated for low rpm to max rpm. A computer measures the rate of acceleration of the rotating mass and calculates rear wheel torque and then does mathmatical formula to determine horse power.

Is my understanding correct? Thanks.

Jim

Hmmmmm.....I think the machine applies load to the wheels (resistance to wheel rotation on the rollers). I do not think anything is measured in terms of the rotational acceleration of the rotating masses. What you get is rear wheel torque (wheel deflected diameter is determined) and wheel spin rate and maximum rotation force is measured (torque). So we end up with wheel rotation speed and torque which is converted to horsepower.

Nothing to do with how fast you accelerated the rotating masses. I am just guessing but when I see a car on a dyno run I see the rear wheels on two BIG cylinders that the rear tires sit on and spin up as the car is tied down on a fixture.

Same on engine test stand where the output shaft is connected to and drives a mechanism applying torque and rpm to that mechanism so you can measure hp at various rpms and thus tune an engine in the same way you can tune an engine on a dyno with the car tied down as explained above.

Jim......,.It is not rocket science. On the dyno measure tire thrust in lbs (sum of both tires). multiply that thrust by tire deflected radius in ft. You now have ft lbs (torque). Measure tire velocity at interface and calculate tire spin rate in radians per second. Multiply spin rate by torque and divide by 550 ft lbs per second (one horsepower). You will then see how many total horsepower you have.

That is what I am thinking today :p

[Hib Halverson]

(snip)

However,

413/.85 (15%** drivetrain loss) = aprox 486 chp, not 513



Paul is correct. I made a mistake with the 15% figure. I apologize for any confusion. I will edit that post to correct the error.

But...I suppose my error with the 15% computation is moot, at least for C4. Back in the day when I was covering ZR1 and LT5 for media, I talked to my pal Jim Minneker, who back then, was Corvette Powertrain Manager, about parasitic loss in the later C4 driveline. He told me that GM testing showed that the average loss in the manual powertrain (ZF S6-40) was 18% and the average loss in the automatic powertrain was 22%.

Since then, with LT5s, I've always used 18% when converting from SAE-net rear wheel power numbers to SAE-corrected flywheel power.

Note that this math only works if you are working from SAE-net rear wheel power figures. It won't work if the chassis dyno numbers are either "standard-corrected" (popular with the aftermarket) or raw uncorrected figures.

Also, if you want to split hairs... there are some other variables:
1) tires
2) lubricant types used in the trans and diff
3) temperatures of lubricants in trans and diff
4) mfg. and assembly variances
5) testing in gears other than fourth

An interesting post script to this discussion is in later years, once C5 was out, I asked a similar question of the folks at GM Powertrain and they told me, with respect to manual powertrains, the C5 (and, obviously, C6) drivelines are more efficient than that of C4 and that the parasitic losses decreased to about 15%. I attribute that to improvements in transmission and drive axle design and manufacturing along with the switch from Cardian type joints in the axles to CV joints and lubricant choices.

[QB93Z]

Since this thread got my thinking, I did a search and found this description of how a DynoJet dyno works.



What is a dynamometer? A dynamometer is a device that measures force and power. There are lots of different kinds of dynamometers, including the kind that test springs and shocks, but we don't care about them because I don't have any. I have an inertia-type chassis dynamometer. It measures the force and power that the spinning wheels of an automobile produce. It is not a "brake-type" dyno that measures the power that is actively absorbed by a water, oil, or eddy-current brake or by a generator. An inertia-type chassis dyno consists of two great big heavy drums hooked up to a computer. The wheels of an automobile spin the dyno drums, and the computer measures the speed.
Simple? If you remember the stuff you were supposed to learn in high school, it is. The computer calculates the acceleration of the dyno drums by continuous measurements of their speed and the time. If the surface of the drums spin from a speed of zero to a speed of 10 feet per second in one second, then their surface acceleration is 10 feet per second per second, or 10 ft/s2. Sound familiar?

Since the rear wheel dyno measures acceleration, drive line rotational mass will directly affect the measured output. So, a light-weight flywheel will "add" horsepower as measured on a DynoJet type dyno. This is because less engine output is used accellerating the mass of the flywheel.

Am I right in assuming that the mass of the flywheel has very little affect on the measured horsepower measured on an engine dyno at constant speed?

Jim

[Paul Workman]

I have a really basic question about comparing Crank HP to Rear Wheel HP.

I believe that an engine dyno measures the power output of an engine on a test stand. The engine is run at a constant, optimum rpm and a machine applies load to the crank shaft and measures the power produced.

I believe that a "Dyno" is a calibrated mass that the car's rear wheels spin as the engine is accelerated for low rpm to max rpm. A computer measures the rate of acceleration of the rotating mass and calculates rear wheel torque and then does mathmatical formula to determine horse power.

Is my understanding correct? Thanks.

Jim

Yep! I recon the only reason to do engine or dynamic (inertia) tests would be for comparison sake, or to document performance before and after modifications (for example).

Is the loss factor a constant, or exponential (or a mixture of factors)? Comparing an LS7 Z06 that is advertised to be 505/≈450 crank to wheel hp to my LT5's 508/432 (fixed 15% factor) it suggests only about an 11% drive train loss for the LS7 vs 15% for the LT5. Apples and oranges (far as C6 vs ZF transmission go) or, as (I think) does rpm play a role? (No replacement for displacement, in other words.)

Bob G and Pete have often expressed their doubts regarding a fixed % conversion factor, regardless of engine size/output, based on real world observations. But, ya know...all of this is so much achedemia when compared to real world results: TIME SLIPS!

I agree w/ Bob G (and others) when they say the real test is speed through the traps. All the BS regarding which conversion factor to use, whether they are dynamic or static, peak or power under the curve, becomes so much :blahblah::blahblah:.

So, I guess (for me) RWHP (under the curve) is far more important that CHP that is extrapolated via a plethora of coversion factors and constants, etc. And, even then, if one is to get an accurate comparison, it makes a lot of sense to use the same dyno on the same day (for example).

p.

[Dynomite]

Since this thread got my thinking, I did a search and found this description of how a DynoJet dyno works.





What is a dynamometer? A dynamometer is a device that measures force and power. There are lots of different kinds of dynamometers, including the kind that test springs and shocks, but we don't care about them because I don't have any. I have an inertia-type chassis dynamometer. It measures the force and power that the spinning wheels of an automobile produce. It is not a "brake-type" dyno that measures the power that is actively absorbed by a water, oil, or eddy-current brake or by a generator. An inertia-type chassis dyno consists of two great big heavy drums hooked up to a computer. The wheels of an automobile spin the dyno drums, and the computer measures the speed.
Simple? If you remember the stuff you were supposed to learn in high school, it is. The computer calculates the acceleration of the dyno drums by continuous measurements of their speed and the time. If the surface of the drums spin from a speed of zero to a speed of 10 feet per second in one second, then their surface acceleration is 10 feet per second per second, or 10 ft/s2. Sound familiar?

Since the rear wheel dyno measures acceleration, drive line rotational mass will directly affect the measured output. So, a light-weight flywheel will "add" horsepower as measured on a DynoJet type dyno. This is because less engine output is used accellerating the mass of the flywheel.

Am I right in assuming that the mass of the flywheel has very little affect on the measured horsepower measured on an engine dyno at constant speed?

Jim



Yes Jim ......at constant speed which is really what we are interested in, rotating mass is not a variable .......not of interest. Most guys talk in terms of maximum horsepower to the pavement. You are specifically interested in having the exact gear ratios (transmission/differential) that will match the top end speed with the top end RPM. If that is not correctly matched, you cannot achieve maximum horsepower at the maximum speed.

If you are drag racing however, you ARE interested in rotating masses such as lightweight flywheels.

[QB93Z]

My conclusion then, is that the conversion factor for Rear Wheel Horsepower to Crank Horsepower is not a constant for a car that is being modified by drive train changes.

So, the 18% that Hib discussed (from GM) would not apply to a C4 ZR-1 with a lightweight flywheel, or different drive train lube, or different differential gear ratio. The effect of all these changes could be measured on a rear wheel dyno (DynoJet type), but none of those changes affect crank horsepower.

The only way to change crank horsepower is to make changes forward of the flywheel. For example porting, tuning, headers, bore and stroke, etc.

Jim

[BigJohn]

Now my headache is back!!
What I really like is having my socks blown off with big torque.
:cheers:

[Blue Flame Restorations]

Now my headache is back!!
What I really like is having my socks blown off with big torque.
:cheers:

Amen, brother:dancing

[Hib Halverson]

Since this thread got my thinking, I did a search and found this description of how a DynoJet dyno works.



What is a dynamometer? A dynamometer is a device that measures force and power. There are lots of different kinds of dynamometers, including the kind that test springs and shocks, but we don't care about them because I don't have any. I have an inertia-type chassis dynamometer. It measures the force and power that the spinning wheels of an automobile produce. It is not a "brake-type" dyno that measures the power that is actively absorbed by a water, oil, or eddy-current brake or by a generator. An inertia-type chassis dyno consists of two great big heavy drums hooked up to a computer. The wheels of an automobile spin the dyno drums, and the computer measures the speed.
Simple? If you remember the stuff you were supposed to learn in high school, it is. The computer calculates the acceleration of the dyno drums by continuous measurements of their speed and the time. If the surface of the drums spin from a speed of zero to a speed of 10 feet per second in one second, then their surface acceleration is 10 feet per second per second, or 10 ft/s2. Sound familiar?

Since the rear wheel dyno measures acceleration, drive line rotational mass will directly affect the measured output. So, a light-weight flywheel will "add" horsepower as measured on a DynoJet type dyno. This is because less engine output is used accellerating the mass of the flywheel.

Am I right in assuming that the mass of the flywheel has very little affect on the measured horsepower measured on an engine dyno at constant speed?

Jim



As "QB93Z" states, inertia dynos measure the time it takes to accelerate a known mass. That number is math'ed to power and that, in turn, is math'ed, using the speed of the mass, to torque.

Brake dynos directly measure torque via a strain gauge and then math that to horsepower. The braking is accomplished by the action of water or oil on a turbine or an eddy-current electric brake

In theory, either type of dyno could measure a change brought on by going to a lither flywheel but could only do that when the engine accelerates.

A light flywheel does not affect power unless the engine is changing speed, ie: if you swap your dual mass wheel for a standard aluminum wheel, it takes less power to accelerate the engine, but the power required to hold the engine at a given speed is the same. That is why when you replace the dual mass with an aluminum wheel, the engine feels more responsive.

[Pete]

I respect the business FBI has today, but the above is statement is nothing but a crock of BS.

The 350 in my 95, when it was built in 1997, made 413-hp at the wheels SAE-corrected which, with the 18% C4 manual driveline loss, maths to about 503-hp at the flywheel. The engine has stock cams, VanDeventer heads, cleaned-up stock manifolds, cats, a Z-Industries cal and a custom-build exhaust which uses Flowmaster mufflers.

And yeah...the drivability is there, too.

Automasters built that motor 15 years ago...when "FBI" didn't even exist.

Hell DRM was building 475-hp 350s 20 years ago.



So i gather when one writes "respect" before or after an insult makes it ok/better.

Well then with respect your Z's 413 rwhp is BS you have any timeslips to back it up.

Hib,practice what you preach back up your 413 rwhp claim, don't insult me with a dyno sheet even if it is with "respect" cause i forgot more about LT5's then you think you know.

Otherwise your the biggest BS'er here with "respect"
I have videos,timeslips,dyno sheets to back mine up.

So start practicing what you preach,till then STFU w/"respect"

You sure your not a politician, i thought only politicians don't practice what they preach.

I have to go change my sig to 1000 RWHP since were throwing and claiming HP #'s with no backing them up, heck i'll make it 1200 rwhp for drivetrain loss. LMFAO

Respectfully
Pete

[Kevin]

So i gather when one writes "respect" before or after an insult makes it ok/better.

Well then with respect your Z's 413 rwhp is BS you have any timeslips to back it up.

Hib,practice what you preach back up your 413 rwhp claim, don't insult me with a dyno sheet even if it is with "respect" cause i forgot more about LT5's then you think you know.

Otherwise your the biggest BS'er here with "respect"
I have videos,timeslips,dyno sheets to back mine up.

So start practicing what you preach,till then STFU w/"respect"

You sure your not a politician, i thought only politicians don't practice what they preach.

I have to go change my sig to 1000 RWHP since were throwing and claiming HP #'s with no backing them up, heck i'll make it 1200 rwhp for drivetrain loss. LMFAO

Respectfully
Pete

there's a company assembling a tt rwd muci that did just this

[XfireZ51]

This is what DRM has on their website TODAY

DRM 600/510 Conversion
1990-95 ZR-1 Corvette
510-530 horsepower/430-450 ft-lbs.
368 cubic inches
Oversized cylinder liners
JE pistons and Oliver rods
DRM intake camshafts
Ported cylinder heads
Ported plenum and
injector housings
K&N air filter
Modified air filter lid
63mm throttle body
Custom computer calibration

So my last dyno run on the Dynojet at Speed Inc. came up w

434rwhp/379rwtq. Using an 18% parasitic loss factor (which I normally have not when quoting numbers) that translates into 529/462 at the crank.

350, stock bottom end
Pete intake cam/stock exhaust cam
User ported Plenum/Inj. Housing
DeVenter ported heads (more meat left on that bone)
63mm TB
Watson 1 7/8" headers w 3" exhaust
My own extensive driveability/WOT tuning (BTW, I've read several DRM chips. They do nothing but play w WOT a bit)

Couldn't find the price for DRM but something tells me I win the bang for the buck contest.

[Blue Flame Restorations]

Quite a comparison, Dom. I can only imagine a closed deck big inch motor in my Turq car.

[QB93Z]

Hib, your post using the phrase "crock of BS" is inappropriate on the ZR-1 Net Registry Forum.

Pete and Hib and FBI, you have all had your say and response and the back and forth needs to stop.

If there is any question about the Forum rules for civil discussion, please contact me off-line.

Jim

[WB9MCW]

http://i126.photobucket.com/albums/p110/HAMMERHATE/FBI-Baseball-Cap.jpg

[XfireZ51]

BRIAN,

WHERE DO I GET ONE OF THOSE HATS????!!!!!

:cheers::dancing

[WB9MCW]

BRIAN,

WHERE DO I GET ONE OF THOSE HATS????!!!!!

:cheers::dancing

right click copy paste for now

maybe Lee will have some made up he seems to be good a such things

[Pete]

It wasn't me,he started it :-D
See what happened you got both of us in trouble.
I punished myself and stood in the corner for 15 minutes.:)
and wrote "i will be nice from now on, even to Hib" 1000 times

In all seriousness sorry to the forum for the trouble.
Won't happen again.

Pete

[bdw18_123]

It wasn't me,he started it :-D
See what happened you got both of us in trouble.
I punished myself and stood in the corner for 15 minutes.:)

:sign10:

[ALZR1]

It wasn't me,he started it :-D
See what happened you got both of us in trouble.
I punished myself and stood in the corner for 15 minutes.:)
and wrote "i will be nice from now on, even to Hib" 1000 times

In all seriousness sorry to the forum for the trouble.
Won't happen again.

Pete

Your A glutton for punishment aren't you.I told you to stay away from keyboard commando.When you get home we are going to have A little chat.


AL.

[XfireZ51]

Your A glutton for punishment aren't you.I told you to stay away from keyboard commando.When you get home we are going to have A little chat.


AL.

Al,

You must beat him about his little Greek head mercilessly!

[Dynomite]

I punished myself and stood in the corner for 15 minutes.:)
and wrote "i will be nice from now on 1000 times

Pete

I bet you were not writing about being nice.....prolly creating some new cam regrind design :handshak: which might take a bit more than 15 minutes but with your great technical background who is to say :D

[FU]

Now now boy's play nice in the sandbox.

[Hib Halverson]

So i gather when one writes "respect" before or after an insult makes it ok/better.
No, "Pete". I'm sorry, but you seem to have misunderstood the statement. It means exactly as posted, but to restate it a different way...earlier you said:


The 350ci/500 would not be possible today if it wasn't for the FBI.


My response was that I have respect for the business and products FBI has developed in recent years. But...the idea that 500 horsepower 350s wouldn't exist if it weren't for FBI's work is ridiculous. Second generation ZR1s with 350-cuin engines making 500 at the wheels go back at least as far as the mid-90s and perhaps as far back as 1992 or 1993, a time that predates FBI's existence by many years. LPE, DRM, Automasters, Haibeck and one or two other ZR1 tuners who were big in LT5s in the 90s were the ones responsible.

Well then with respect your Z's 413 rwhp is BS you have any timeslips to back it up.

"Timeslips" are issued by drag strips to document quarter mile passes. Rear wheel power figures are generated by chassis dynamometers. To support the 413 rwhp number, I have only chassis dyno data.

...cause i forgot more about LT5's then you think you know.

Ah geez."Pete". You sound like the hobby's latest JohnRovner. Can't you be more original? If I had a nickel for everytime someone has said that, I'd be freakin' rich. I have been covering ZR1 for media since 1987 and have been working on them, occasionally, since 1989 and, regularly, since 1995. While admittedly, I don't work on them for a living, I'm satisfied with my knowledge of the LT5 engine.

I have videos,timeslips,dyno sheets to back mine up.

I'm glad you have that content, but what is it you are going to back up? I wasn't questioning any claims about performance of FBI products. I stated that the idea that 500 horse 350s would exist if it hadn't been for FBIs work was ridiculous.

[Blue Flame Restorations]

Just close this stupid thread down. This isn't even my fight. I mean, really? I'm far from an expert but I can see where someone likes to talk just to hear his head rattle.

I used to know a kid who had a subscription to every auto mag under the sun. He thought he was an expert because he could read and write. Drove everyone nuts with his reading ability and lack of practical experience.

Dejavu

[youngrm]

Not to change the subject, but PETE, it would be interesting to hear more about the engine producing 700 hp....? TIA

[ScottZ95ZR1]

I'm far from an expert but I can see where someone likes to talk just to hear his head rattle.

I used to know a kid who had a subscription to every auto mag under the sun. He thought he was an expert because he could read and write. Drove everyone nuts with his reading ability and lack of practical experience.

Dejavu

Well damn, Brett. At least I chose to join the Navy over becoming a technical writer for those magazines I like to read! :-D