Horsepower reality check,.. Grumpy?

[John Scott]

I'm hearing lots of claims of 450, 500, even 600 hp from the 383 sbc. Grumpy, I like your dyno program. It seems to be more realistic and in tune with the builder I'm using, and a few other racing fanatics I know. We all read the 500 hp claims of performance part maker X and others, that if plugged into your program, would be obviously less. Since 500 hp is becoming the benchmark of many production cars and street rodders as well, using a well matched head/ cam intake and compression, on pump premium, could you give a possible component combination for a 383 making (flywheel) 450 hp, 500, and 550? In other words, no brand names needed, assuming all other parts being well matched, how much head flow in cfm, (using a realistic good aftermarket head) compression, cam lift/duration is necessary for these figures? ( w/o a power adder, I doubt that 600 can be accomplished and still be considered streetable, no?)

4/8: Once we have our engines in the car, the 1/4 mile is a pretty good tool for figuring how much we get to the ground by using the trap mph figure.

(mph x .00426)(mph x .00426)(mph x .00426) X weight in lb...or just go to prestage.com and use their car math. Interesting to note on a 2700lb car approx. 450 flywheel, 360rwhp= 120mph, 500, 400rwhp=124, 550, 440rwhp=128, but until then we ask Grumpy

JS

[Mikelly]

...I'm also in this boat, and one thing you constantly have to get clarification on is Flywheel vs. wheel HP. That issue is enough to confuse almost anyone... I know that my current build SHOULD produce about 530-540 FLYWHEEL hp. However, any number of things could change that number drastically.

 

Grumpy's info is excellent reading, which helps dispell some of the rumors!!

Mike

[grumpyvette]

ok first things first,remember its very hard to exceed 1.3 hp per cubic inch of displacement N/A so build bigger if in doubt,and everything should match the ONE rpm range that you want the engine to operate the most efficiently at. next theres a trade off of static and dynamic compression ratios to rpm potential, play with these formulas/programs and see what I mean.

 

http://cochise.uia.net/pkelley2/DynamicCR.html

 

this one has a GREAT DYNAMIC CPR calculator program software for FREE!

 

http://cochise.uia.net/pkelley2/crc.htm

heres one for static compression ratios

 

your aproximate hp potential from cylinder head flow with the formula (.257 x flow at max cam lift x 8= hp potential) but the formula figures,your building an engine where the heads are the restrictive part in the airflow while in most cases the intake,headers,carb,cam or exhaust system is really the restriction.

 

you ask me not to name manufactures but, as a general guide you need

255cfm port flow for 450hp

275cfm port flow for 500hp

310cfm port flow for 550hp

and your correct your not getting 600hp without power adders or special heads or going above 350-383 cid (remember every head needs a pocket port clean-up to flow correctly ,no heads work great out of the box)

 

good heads for 450 hp

sportsmanII

IRON EAGLE 215cc

pro LIGHTNING 215cc

trickflow 23deg std

for 500hp

world products 220cc motown

195 cc afr

195cc canfields

trickflow 23 deg ® heads

for 550 hp

210cc ported AFR

223cc PORTED CANFEILDS

230cc PORTED DART PRO 1

 

examples

http://www.ryanscarpage.50megs.com/combos.html

 

450hp

#10,#19,#20,,#44,103,#92#14,#15

500hp

#71,#17,#93,#102

550hp

http://www.shafiroff.com/ultrastreet.html

http://www.gochampion.com/sbcengdm.htm

[danj]

This is an interesting discussion. Would be good to put everyone on the same playing field for HP claims. I'm having a 383 sbc installed in my 83ZXT 2+2. Builder claims 430-440 HP. Will be anxious to run the numbers for the reality check.

Would also like to extend that to performance estimates on the 1/4 mile track but I am not sure what my vehicle weight would be.

 

Any ideas on what an 83ZXT 2+2 with 383 sbc (iron vortec heads), 700R4 would weigh in at?

 

DanH

[John Scott]

Grumpy, your knowledge and resources are phenominal! I still wonder how AFR can claim 500 hp from a 260 cfm head. About 15 cfm short. Hmmm.

Reading some of the tests, it can be a bit misleading to say your engine will run the same in the controlled enviroment of the dyno room as in a hot engine bay pushing through restrictive exhaust. In the right context, its a great tool for tuning and reference. Thanks again! www.Prestage.com car math for wheel hp from et or mph in the 1/4. usually .8-.85 of flywheel.

JS

[Z-Dreamer]

I spoke with my engine builder last week, turns out he got a "deal" on a flow bench, I think he said it's a Super Flow 600? He had been sending his porting jobs out to be flow tested previously. Anyway, since I've sent some business his way, I'm going to let him test his "New Toy" on my Pontiac Motorsport heads so I'll get some "Real" numbers finally.

 

Mark

[Guest 1fastz]

well my car DYNOED at my chasis dyno at 498 rear wheel horses on the motor with a 383..

 

and yes that was pump gass and I can drive it daily .. although the valve springs wont last to long ..

 

and yes 600 horses is doable with good heads and 400 cubes my dart pro1 heads on a 408 cube motor with my same combo would break 600 as im right there as it is..

 

also afr heads do not need a bowl cleanup as they are cnc ported out the box and the short turn and valve area is already worked.

 

technology has come a long way

[John Scott]

Originally posted by 1fastz:

well my car DYNOED at my chasis dyno at 498 rear wheel horses on the motor with a 383..

 

and yes that was pump gass and I can drive it daily .. although the valve springs wont last to long ..

WOW! 498 at the wheels. Figuring the .8-.85 or so loss to the wheels, that would put you in the high 500-low 600 hp flywheel. What cfm do your Dart heads flow? Your cam, I'm trying to remember, .600 250-60 duration?? 130mph+ in the 1/4 for a 2700 lb car. I know you've passed on this question before, but is this about what you run on the motor?

JS

[Guest 1fastz]

well here are the numbers..

 

car weighs 3258 pounds with driver and gass and full nos bottle.. < i have a full cage and its last year 280 Z and I weigh 238 >

 

car has run on the bottle as fast as 9.72@143 mph..

 

never have run it on the motor at the track with normal timeing.. I do know with the timeing at only 22 total < or where I run the timeing when i spray > i have pulled off a 10.92@124

 

ON our dynojet 248 dyno I made 498 rear wheel horses.

 

motor is a 383 11-1 with elgin 4340 crank eagle 4340 5.7 inch H beam rods trw forged piston total seal gapless piston rings.

 

heads are not pro-1 but are the same casting dart changed the name they used to be called dart conquests .. the heads are 318 cfm on the intake..

the cam is a cran solid roller 255 intake 265 exhaust @ .050 with 633 lift straight across.

 

intake is a weiand team G high rise.. I have underdrive pulleys with a serpentine conversion on the front and a black magic electric fan.

[grumpyvette]

just one question?

1fastz

while the performance of that nitrous enhanced engines horsepower is damn impressive what does the fact that hp gained through adding nitrious and fuel have to do with the discussion? since you can add fuel and nitrous in increaseingly larger amounts to any sbc engine to reach any power level you choose if direct port injected nitrous/fuel is used untill the pistons melt or the crank snaps, and even a plate system can get 500plus hp, the use of nitrous has nothing to do with the normal 1.3hp per cubic inch hp limit of N/A engines.

and as John Scott said" , how much head flow in cfm, (using a realistic good aftermarket head) compression, cam lift/duration is necessary for these figures? ( w/o a power adder, I doubt that 600 can be accomplished and still be considered streetable, no?) please dont take this a criticism,of what you have acheived with that car, its not! its just that a nitrous engine is not a reasonable example here. turbo charged sb based chevys of only 202 cubic inch displacement running toluene /nitromethane mix and 60lbs of boost get 1600 plus hp but thats not a reasonable example either.

[blueovalz]

Thanks for re-focusing this sting to a NA set-up. It's been very good reading along with some other strings. I've learned some good things I've done, and some bad, and I guess in the end it really won't matter 'cause I aint yanking the motor to change a few things that really won't amount to a tinkers damn on the street.

[John Scott]

Wait a minute, even though 1fastz is running some really fast time on the bottle, his discussion is right on topic. He did state that his engine was dyno'd at rwhp498, no nitrous. On the bottle, you would see those numbers climb to 700+ rwhp. Using the weight of the car and a 124 mph ON THE MOTOR, with compromised timing, the numbers do add up to a very impressive horsepower within the dynojets claims. Thanks for the cam specs and headflow. Although my builder would argue that Pro1s have advanced in their design since conquests, not just a rename, 318 cfm, according to Grumpys chart could get you past the 550 mark. Obviously some good flow work. I think we've resolved few heads flow really well out of the box. Streetable? That's a matter of opinion. In the 80s, I used to drive my 11.5:1 600+ lift 256 duration 106 LSA cammed car pretty regularly. My new motor is somewhat tamer than yours, by about .033 lift and a little less than 10 degrees duration. With a long duration and alum head, 11:1 pistons will work with pump gas. You've stated that you ran pump gas. I think your discussion is valid here. 124mph with a 3000+ car? Car math says you're pushing real close the the 550-600 mark.

[MYRON]

Just as an example:

One of my best friends has a 70 camaro with:

 

383 CI

10.5 compression ratio

Brodix 11x or Track One's(cant remember)modified to flow 335CFM

.660'ish roller cam + crane gold 1.60 ratio rockers which brings that # up...

 

That is the basics and it Dynoed 602 NA HP

 

Myron

[grumpyvette]

just pointing out a pattern here guys(notice it takes these heads that flow over 310cfm-320 plus cfm to get those high hp numbers? )

and like the formula says( .257 x intake flow x 8 = potential hp so 310cfm x .257 x 8=637 potential (N/A) hp. now since an engine running N/A has about21% oxygen to mix with fuel and burn and nitrous has about 40% oxygen to burn with the fuel in theory a engine that makes 600hp n/a can make 1.9 times that hp on a full nitrios injected fuel load or 1143 hp , of course other factors like the crankshaft ripping out holes in the oil pan tend to prevent that with all but the best most expensive parts

[Kevin Shasteen]

All Right! New formula for theoretical HP; Thanks Grumpy.

 

Also; anyone swapping CFM #'s for cylinder heads needs to find out what pressure drop those readings were taken at.

 

Most cfm's are taken at either 5, 12, 25 or 28".

 

If one cfm reading was taken at a particular pressure drop & you want it at another, simply do the math:

 

New Pressure Drop = ((SQRT)NPD/OPD))...then multiply your answer by each cfm measurement given at .100" incriments for your particular cfm printout.

 

NPD = New Pressure Drop

OPD = Old Pressure Drop

 

Such as, lets say the previous spoken 310cfm was taken at 28" & you want it to be 25":

 

EX: 25"/28" = .892

SQRT of .892 = .945

Now take your CFM (310) & multiply it by .945

310cfm X .945 = 292.95cfm @ 25" pressure drop

 

Dont forget one reading in California wont be the same as Colorado: make sure you know what your pressure drop readings are when swapping cfm readings when calculating theoretical HP.

 

Still love the math thing regarding airflow of an engine & yes-I'm still only an Inliner

 

Kevin,

(Yea,Still an Inliner)

[silicone boy]

Great thread guys, very informative and I love the math. I guess what it all amounts to is thatI have to get a lot more atmospheric pressure up here in Denver (or spend more cubic dollars )

[Guest the_dj]

I removed my question for grumpy from this spot because I realized it was stupid.

 

Thanks,

DJSS

[Guest super280z]

Such as, lets say the previous spoken 310cfm was taken at 28" & you want it to be 25":

 

EX: 25"/28" = .892

SQRT of .892 = .945

Now take your CFM (310) & multiply it by .945

310cfm X .945 = 292.95cfm @ 25" pressure drop

or, just look on the back of the AFR catalog sorry Kevin, didnt mean to rain on you're parade, but i couldnt pass this one up.

[Kevin Shasteen]

Originally posted by Super280z:

or just look on the back of the AFR catalog [/QB]

Hey, you cant rain on my Parade; keep in mind that 'Destiny' has me forever an Inliner...therefore, "Everyday is a [Rainy Parade Day] for me! I dont remember when the last time I purchased a new catalogue as I havent started a new project in years.

 

Its nice to know they (at least AFR) is putting that info into their catalogues: it's about time somebody started offering that info.

 

I need a new project/I need a V8

 

Kevin,

(Yea,Still an Inliner)

[Guest 1fastz]

Yes I made 498 rear wheel horses ON THE MOTOR .. on the bottle I make about 700 horses AT THE REAR WHEELS..

 

the car runs a single stage 250 shot plate kit on it..

 

Yes i agree it takes head flow but my point is with the corect parts its not only possible its being done regularly by people.

and not even with exotic parts ust good quality items

 

there are no less then 10 heads i can think of that would support 600 NA horses at 11-1 compresion< the limit for pump gass with a large cam > when fully ported

 

canfield

afr 220 227 and up

edelbrok victor

brodix track 1 and -8 through -11

dart

pro action

trick flow

to name a few.