don't mean to make you feel bad, but I think you should pull much better than that with a BB 496..... I have a very similar setup running a 383 and I pull over 435tq and 440hp at the rear wheels.... I would expect a 496 BB to pull another 100hp,,...

O, and "So it made 404hp on the first pull and 468hp on the last?Assuming a 25% parasitic loss that puts you at 625hp. Maybe more is the loss is a higher ""


math is off... 468*1.25=585...



I am just saying, something may be holding you back.... I think you should have more....

but yes, I know the feeling of 40mph rolling burns!!!! very very

I can burn all the way through 2nd, and lay chirps from 3 to 4th at over 100.... C3's rule!!!! imho

 

That's not how to back out a percentage loss. You are adding 25% of 468 back in. You need to add back in 25% of what the motor made before 25% came out. You should take 468 / .75 to get back 25% of loss. Now, if you take 624hp and sutract 25% of loss from that, you get 468 hp at the rear.

Your motor at 440hp with a manual with 15% loss is 440 / .85 would be 517hp. That's sounds about right from what I've seen on the engine and chassis dyno here.
Sounds like you both are making about 1.3 hp per cubic inch. That's pretty good!

I'm more of a small block guy myself, too!

 

+1

I used .75 multiplier, sometimes .70 if there is a lot of parasitics....(Like on mine, I would be lucky to make 450rwhp I'm guessing)


And if you were to run the 440rwhp stick shift Vette at the track and the 468rwhp auto vette at the track, both on slicks with the appropriate rear gearing...there will be about .75-1 sec difference between them...Auto trannies and stall converters really screw with the rear wheel HP numbers but at the track....putting all that power down almost instantly makes all the difference.

440rwhp is very stout for a SB though....no doubt....That car should run mid to low 11s....

My buddy has a 66' Vette, Doug Nash 5 spd, with a solid roller 388", AFR 195s and TPIs super ram FI system and it only makes 420rwhp, his car ran an 11.80@115 at 3400lbs with a low 1.6 60'......

 

So..... Your saying it takes 107 more hp at the crank to produce in his case with an auto 26 more hp at the wheels? And the extra weight of a bb? And I do have a lot of the parasetics.... Ps wp alt and now ac.... And I have been told with manules it's more like 17%????? And the new builds of autos with the torque locker it's more like 19%

but.... Again this is my understanding.. And I could be way off.....jmho

 

Those numbers are easily in the ball park.... A T400 easily consumes 40-50hp by itself to run....not to mention its a percentage loss, not an actual HP lose.

As for the weight, the BB is about 160-180lbs heavier then a stock SB....you put aluminum heads on it, that cuts about 80+lbs off of the total.... So a BB with al heads may be 100lbs heavier then an iron head SB.

You are also correct on the parasitic losses of the manual trannys....general rule of thumb is 15-17% parasitic loss but I still think that in an old Vette with IRS, that number is probably more like 17-20%.....especially if stock accessories and clutch fan are installed...

Ofcourse all of this is just my opinion. I have not done a chasis dyno on my car yet but I have some of my other cars. I have engine dynoed my engine twice on different dynos.

New trannies like 4l60e autos do consume less power but are still well into the 20%+ loss range. Same thing with the TH200r4. Powerglides consume the least amount of power out of the old trannies...

 

[QUOTE=pauldana;1573553222]don't mean to make you feel bad, but I think you should pull much better than that with a BB 496..... I have a very similar setup running a 383 and I pull over 435tq and 440hp at the rear wheels.... I would expect a 496 BB to pull another 100hp,,...

O, and "So it made 404hp on the first pull and 468hp on the last?Assuming a 25% parasitic loss that puts you at 625hp. Maybe more is the loss is a higher ""


math is off... 468*1.25=585...



I am just saying, something may be holding you back.... I think you should have more....

i know whats holding me back....Fear and common sense... lol j/k i have a standard hei ignition, probly the biggest contrubuting factor for bigger numbers>>>it is first and formost a street car! full interior with a DVD player!! (which is rad). but Horsepower was not the intent of the build. it was huge trq numbers very quick in the rpm range. and the goal was achieved.. 611 final trq at 6100rpm. i had about $12,ooo to do this engine and still was not enough... so i am piecing together the rest like msd ignition and maybe a electric water pump and other stuff.... I just purchased a 7ooo lbs lift for my pole barn which i will be installing on Sunday.... it seems i always got some thing else going on, to take away from the Vette fund.... but i will post pics of the Lift install.... thanks for all the kind words from every body this has truly been an experience... And yess C3's Rule!!!!

 

i don't remember>>> it was 2 and a half years ago when i purchased the 496 rotating assembly from eagle...

 

a volumetric efficiency calculator done at the dyno dictated what jets an power valve to use, i can't recall what the final jetting for this carb was but it was close out of the box fuel curve was very very close but the secondaries jets were to big. and the power valve that the quick fuel carberators came with was not even close... my spark plugs by pull 4 were very nice showing no signs of detonation and the fuel curve was on.. the car no longer broke up on the top end...

 

same exact pistons, crank, block, heads as my engine. I went 8.30 with a 400 hp shot of nitrous. 9.80's on motor. I just had a solid roller cam and springs. I also was running a 1050 dominator.

 

[QUOTE=Neptune75;1573557138][QUOTE=
"So it made 404hp on the first pull and 468hp on the last?Assuming a 25% parasitic loss that puts you at 625hp. Maybe more is the loss is a higher ""


math is off... 468*1.25=585...



I am just saying, something may be holding you back.... I think you should have more....

i know whats holding me back....Fear and common sense... lol j/k i have a standard hei ignition, probly the biggest contrubuting factor for bigger numbers>>>it is first and formost a street car! full interior with a DVD player!! (which is rad). but Horsepower was not the intent of the build. it was huge trq numbers very quick in the rpm range. and the goal was achieved.. 611 final trq at 6100rpm. i had about $12,ooo to do this engine and still was not enough... so i am piecing together the rest like msd ignition and maybe a electric water pump and other stuff.... I just purchased a 7ooo lbs lift for my pole barn which i will be installing on Sunday.... it seems i always got some thing else going on, to take away from the Vette fund.... but i will post pics of the Lift install.... thanks for all the kind words from every body this has truly been an experience... And yess C3's Rule!!!![/QUOTE]



Hp =(tq*rpm)/5252...... thus if I am correct... and again I could be wrong.... but taking this formula hp=(611*6100)/5252=710hp.......

So... if you had 710hp at the rear wheels, using the say 25% loss thing....that would put you somewhere around 890hp at the crank??

So.. that also is hard to believe.... I must be doing my math wrong again...... can someone explain these numbers to me so I can better understand?

Also... would you be so gracious as to post a scan of the Dyno results?

I know that before I fixed my valve spring problems I was tq out ar ~3500..... after spring replacement it went flat at around 5.5k..... Similar cam.... but you are going flat around 6100... correct?

My hp numbers followed this formula very close for my 383


Thank you, i am just trying to understand better.... knowledge is power


C3 DO rule!!!:lu rk:

 

I had bought a Herbert racing solid roller with alot more lift and springs with titanium retainers ,a high rise single plane intake and a holley 1050 at first.. but my machine shop talked me out of it... so i sold most of it on flea bay... but now i sit here staring at your pic(wheel stand) and I'm wondering if i made the right choice..... i have followed some of your threads your vett is killer!!!! what kind of spray kit did you end up with? any stages? i'm still considering spraying it after a ignition upgrade and a rear end over hall when cruising season is over..

 

Im going to spray 150 when I finish the rest of the mods.... that will be more than enough to fix most problems, with what I already have....

 

Since I am now going to a turbo set up, my nitrous set up is forsale. that includes the Profiler sniper JR intake that retail at 500 alone, professionally port matched to AFR 335 cnc heads ($400 cost) Speed tech nitrous fogger ($820 cost new), good to over 500hp shot of nitrous, professionally bent and fitted to the intake. I'll sell it to you for $1100 plus shipping.
I also Have my solid roller lunati cam spec'd by UDHarold ( famous Cam designer on Team Chevelle.com) for sale, I'll sell that for $100. You will most likely need a spring upgrade to use it though, it has .708 lift.

Essentialy you will have my old combo and go deep into the 8's with out much effort. assuming you have your suspension setup right.

 

Oh and I was making 570 hp to the wheels on motor, when I dyno'd my car with that combo. over 1000hp to the wheels on spray.

 

570 on motor!!! ... whats the status on the turbo? i was checking your old threads i like the "fun racing pics thread" i now have a new screen saver thanks to you..... what kind of et's u plan on making with the turbo set up what kind of rear wheel power? sorry i ask alot of questions but i am really really interested in your build... i would definitely by your intake but i did not set the rings up for that kind of spray... i noticed you made some pulls at Milan i go there often you will have to let me know when your going back i could possibly meet you there... i would love to see that car in action!!!!