RWHP loss ??? How ??
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 864
Likes: 2
From: Jax FL
RWHP loss ??? How ??
How would a professionaly modified car that dynoed at 486 rwhp at the build/install.......now still running like a bad a$$ and the tune appears to still be fine now dyno at 425 rwhp???? 
It was dynoed on the west coast at 100' above sea level and the shop here is at 16' above sea level (it appears that both dyno's are Dynojets.
the heads have been refreshed with about 13000 miles on them. It has not been raced, launched hard but the gas peddle does sometimes get that Toyota thing/issue and stick
60 horsies is a bunch to be missing and not have any issues with the car/tune
any ideals out there
It was dynoed on the west coast at 100' above sea level and the shop here is at 16' above sea level (it appears that both dyno's are Dynojets.
the heads have been refreshed with about 13000 miles on them. It has not been raced, launched hard but the gas peddle does sometimes get that Toyota thing/issue and stick
60 horsies is a bunch to be missing and not have any issues with the car/tune
any ideals out there
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
425 / 485 = 13% about normal
Internal drive line friction most likely is the causes
a few things 13,000 miles without a refresh is TOO LONG.
when was the last time you changed your clutch and clutch fluid
light wt clutch, as in carbon fiber disks ?
Oil change ? and what oil wt ?
last time changed transmission and diff fluids ?
in the trans is it stock? 22 degree helix angle gears ? or straight cut gears ?
the diff, stock or light wt racing ?
wheel bearings? stock or racing ?
drive shaft, stock or carbon fiber
Rear wheels. Stock, big heavy cool looking wheels, or light wt racing wheels ? <--- biggest effect on rear wheel HP
Many things effect drive line loss
HTH a bit
Internal drive line friction most likely is the causes
a few things 13,000 miles without a refresh is TOO LONG.
when was the last time you changed your clutch and clutch fluid
light wt clutch, as in carbon fiber disks ?
Oil change ? and what oil wt ?
last time changed transmission and diff fluids ?
in the trans is it stock? 22 degree helix angle gears ? or straight cut gears ?
the diff, stock or light wt racing ?
wheel bearings? stock or racing ?
drive shaft, stock or carbon fiber
Rear wheels. Stock, big heavy cool looking wheels, or light wt racing wheels ? <--- biggest effect on rear wheel HP
Many things effect drive line loss
HTH a bit
Last edited by AU N EGL; Jul 24, 2010 at 07:08 AM.
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 864
Likes: 2
From: Jax FL
425 / 485 = 13% about normal
Internal drive line friction most likely is the causes
a few things 13,000 miles without a refresh is TOO LONG.
when was the last time you changed your clutch and clutch fluid
light wt clutch, as in carbon fiber disks ?
Oil change ? and what oil wt ?
last time changed transmission and diff fluids ?
in the trans is it stock? 22 degree helix angle gears ? or straight cut gears ?
the diff, stock or light wt racing ?
wheel bearings? stock or racing ?
drive shaft, stock or carbon fiber
Rear wheels. Stock, big heavy cool looking wheels, or light wt racing wheels ? <--- biggest effect on rear wheel HP
Many things effect drive line loss
HTH a bit
Internal drive line friction most likely is the causes
a few things 13,000 miles without a refresh is TOO LONG.
when was the last time you changed your clutch and clutch fluid
light wt clutch, as in carbon fiber disks ?
Oil change ? and what oil wt ?
last time changed transmission and diff fluids ?
in the trans is it stock? 22 degree helix angle gears ? or straight cut gears ?
the diff, stock or light wt racing ?
wheel bearings? stock or racing ?
drive shaft, stock or carbon fiber
Rear wheels. Stock, big heavy cool looking wheels, or light wt racing wheels ? <--- biggest effect on rear wheel HP
Many things effect drive line loss
HTH a bit
Thanks but both dyno values are "rwhp"
I was told 20,000 -25,000 would be the refresh threshhold (it's a dd)
It has an flt level 5 tranny (auto),... fresh redline 15w50 oil
cray scorpion wheels
It has an A&A built stroker, heads refreshed via RPM and other than the tranny as mentioned the drive line is stock, but it is the same stuff as the original dyno.......so I am still confused about 60 horses missing on a car that is running Great???
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Refresh on a stoker or any semi race engine should be yearly. or 6000 miles. IF THAT. It does not HAVE to be refreshed for 20-25K but too keep the power up much sooner
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
Safety Car
Joined: Mar 2007
Posts: 3,518
Likes: 37
Can you search the newspaper archives for exact temp and humidity for the days they were done? And add in the different sea levels? Might be interesting if an expert here can opine whether it would make the difference.
Was it with the same tune? Same tuner? Was it one pull only, I know some places will do just a pull or two for a few bucks and not tune?
Was it with the same tune? Same tuner? Was it one pull only, I know some places will do just a pull or two for a few bucks and not tune?
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 864
Likes: 2
From: Jax FL
Refresh on a stoker or any semi race engine should be yearly. or 6000 miles. IF THAT. It does not HAVE to be refreshed for 20-25K but too keep the power up much sooner
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
I use only cheveron 93 oct. it was a SoCal car and their best is a 91oct.
Thanks
Drifting
Joined: Jan 2008
Posts: 1,722
Likes: 138
From: Florida
St. Jude Donor '09
How would a professionaly modified car that dynoed at 486 rwhp at the build/install.......now still running like a bad a$$ and the tune appears to still be fine now dyno at 425 rwhp????
It was dynoed on the west coast at 100' above sea level and the shop here is at 16' above sea level (it appears that both dyno's are Dynojets.
the heads have been refreshed with about 13000 miles on them. It has not been raced, launched hard but the gas peddle does sometimes get that Toyota thing/issue and stick
60 horsies is a bunch to be missing and not have any issues with the car/tune
any ideals out there
It was dynoed on the west coast at 100' above sea level and the shop here is at 16' above sea level (it appears that both dyno's are Dynojets.
the heads have been refreshed with about 13000 miles on them. It has not been raced, launched hard but the gas peddle does sometimes get that Toyota thing/issue and stick
60 horsies is a bunch to be missing and not have any issues with the car/tune
any ideals out there
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 864
Likes: 2
From: Jax FL
I love the way this car runs and I picked it up in SoCal a year ago this weekend and it feels the same to me.
The engine builder/installer/tuner is one of the most if not the most reputable shops in SoCal if not the country and I did extensive research checking the seller out and and he is a stand up guy whom knows his car stuff..... I am very confident that both the seller and the shop that did all the work would not intentionaly mis-inform or move numbers....I am wondering if dyno calibration could be an issue??....the one here in Florida is just over a year old the one out in CA. I am guessing is much older but on the other hand the shop in Ca. has much more expieriance than the one here.
I have pm'd the seller ......he's pretty sharp, hopefuly he can clear this up for me.......not much I can do either way and the car runs great.
one of the stupid things that bothers me now is that I just ordered 200 bucks worth of billet hp badges (now I will be the one with exagerated numbers)
The engine builder/installer/tuner is one of the most if not the most reputable shops in SoCal if not the country and I did extensive research checking the seller out and and he is a stand up guy whom knows his car stuff..... I am very confident that both the seller and the shop that did all the work would not intentionaly mis-inform or move numbers....I am wondering if dyno calibration could be an issue??....the one here in Florida is just over a year old the one out in CA. I am guessing is much older but on the other hand the shop in Ca. has much more expieriance than the one here.
I have pm'd the seller ......he's pretty sharp, hopefuly he can clear this up for me.......not much I can do either way and the car runs great.
one of the stupid things that bothers me now is that I just ordered 200 bucks worth of billet hp badges (now I will be the one with exagerated numbers)
Former Vendor
Joined: Apr 2006
Posts: 2,470
Likes: 2
From: Portland OR
St. Jude Donor '10-'11-'12
Refresh on a stoker or any semi race engine should be yearly. or 6000 miles. IF THAT. It does not HAVE to be refreshed for 20-25K but too keep the power up much sooner
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
Drifting
Joined: Jan 2004
Posts: 1,419
Likes: 6
From: Alamosa CO
I'd like to know the answer to that one too! My 416 is getting close to that amount of miles and is running stronger than ever. I can see maybe changing my valve springs at 10k or so because of the big cam I have, but to refresh the motor at 6k is just rediculous.
Jimbo
Jimbo
Race Director
Joined: Sep 2005
Posts: 11,060
Likes: 291
From: Pasco WA
Everything AU posts seems to be seen through the eyes of a race car driver/owner. Maybe his race car maintenence regimen is a little stringent for a street car? Not to mention, personal opinion. About the only thing you'd really need to maintain, is clean fluids, and on big cammed cars, springs, but only about 10-20k miles, depending on cam size. Just MHO.
Racer
Joined: Feb 2010
Posts: 388
Likes: 0
From: Effingham IL
Refresh on a stoker or any semi race engine should be yearly. or 6000 miles. IF THAT. It does not HAVE to be refreshed for 20-25K but too keep the power up much sooner
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
ie things just loosen up as your engine may be showing.
also what fuel? Fuel now is E15% and a few years ago there was not any alcohol in fuel. That can make up for some of that loss too.
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
Since I have been on this forum I have seen dyno numbers on stock LS1 and LS6 engines vary by as much as 40 hp on the Dynojet 248.. Its absolutly crazy! I guarantee they don't come from the factory with that type of variance... People tend to believe that getting on a dyno is like getting on a scale to weigh something and coming up with an absolute number... The dyno is a tuning tool.. Thats it.. Stick with the same type/model dyno and the same tuner or technician.. I have had my car on 3 different dynos (All dynojet) in Dallas and the numbers have been between 360 and 381 Also.. Shawn at Corvettes of Dallas had some technical problems with my car only at a Dyno day for Forum members,, I was a little upset when my 1st dyno pull on the Z06 was only 267 rwhp.. Turned out the dyno would not give an output number above 4300rpm
Also.. Shawn at Corvettes of Dallas had some technical problems with my car only at a Dyno day for Forum members,, I was a little upset when my 1st dyno pull on the Z06 was only 267 rwhp.. Turned out the dyno would not give an output number above 4300rpm
Last edited by David426; Jul 24, 2010 at 05:55 PM.
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 864
Likes: 2
From: Jax FL
Yeah the sellers ideal of refresh at 20-25K was valve springs. This is an all forged A&A built unit and the heads were refreshed via RPM a thousand miles before I bought it which was a year ago this weekend and I have put 13k on it since......
the Florida tuner and his dyno simply can't find the numbers (over 60rwhp) that is on the A&A dyno sheet
I have pm'd the seller so maybe that will help clear up some of the vast variance between the two....I will post what I hear He is a pretty sharp car guy. 
the Florida tuner and his dyno simply can't find the numbers (over 60rwhp) that is on the A&A dyno sheet
I have pm'd the seller so maybe that will help clear up some of the vast variance between the two....I will post what I hear
He is a pretty sharp car guy.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Everything AU posts seems to be seen through the eyes of a race car driver/owner. Maybe his race car maintenence regimen is a little stringent for a street car? Not to mention, personal opinion. About the only thing you'd really need to maintain, is clean fluids, and on big cammed cars, springs, but only about 10-20k miles, depending on cam size. Just MHO.
Many engine builds well say 20k no problems. other builders will tell you 3-4 races. So it depends on the intended purpose of the build. and in many builders and those we see on race tracks opinions the cam lift & valve train is the biggest determining factor
same builder who tell us no problems with 20k miles, but how hard is the engine pushed ?
We / I see lots of built LS2s LS6s, LS3 and LS7s on road course. and many variations in size and blocks.
by far the most reliable engine is the LS6 crate with added accu-sump, then the LS7 crate dry sump ( with AER or LPE tank) stock engines.
any build engine combination with a cam lift over .600 is the least reliable does not matter what size or who built the engine. Even extremely reputable engine builders / forum sponsors.
then LS3s with out dry sumps.
again these are punished very hard with constant 3000 to redline use 4-5 times every two mins for 20 to 40 min at a time for two / three days. This comes from ON track experience.
Last edited by AU N EGL; Jul 25, 2010 at 03:36 PM.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
I change all fluids and refresh heads as needed on my sons stroker, Daily driver now has 86,000 hard miles on it and allot of track time. Im planning a bottom re-fresh at 100,000 miles Forged all motor Ws6 511rwhp Maintance is key to longevity. It still screams but it does smoke only after a hard run then clears right up.
Racer
Joined: Jun 2010
Posts: 462
Likes: 0
From: Port Richey FL
well just a shot in the dark here, but as far as ur tuning goes, i know like the normal ecu store drive data and adjust fuel maps based on the type of driving, its not common but i've seen some after market tuned computers that still do this. adjusting fuel curve for the way u drive if the previous owner only raced the car the maps were all adjusted for that style of driving, now that ur daily driving it the maps store the data on how u drive and adjust accordingly, i dont know if map adjustments could make that big of a diffrance but it could be part of it, but like i said just taking a shot in the dark here im new to vetts.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I saw 4-1/2% with the change from summer to winter fuel. You can see differences in weather station information, etc. as well. Other things are STD vs. SAE and the amount of smoothing between the two dyno sessions. If the dyno curves are the same basic shape, then I wouldn't worry. One thing I would look for is drops in the new dyno curve that might indicate tired valve springs. The dyno curve isn't posted so it is hard to tell if the curve is smooth or not.
If the car feels as strong, I would take it back to the same dyno next year and see how it does, that will indicate whether something is degrading with the motor, which I highly doubt.
If the car feels as strong, I would take it back to the same dyno next year and see how it does, that will indicate whether something is degrading with the motor, which I highly doubt.
Melting Slicks
Joined: Dec 2003
Posts: 2,857
Likes: 2
From: pawleys island sc