Thread: Any website that calculates HP?

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Originally Posted by kitz

Down to 287 hp with those heads ..................


Kitz

Couldn't you have done that before I bragged on them so much,,,ouch!

faylur, when a converter is advertised at 4500-5500 it doesn't meen thats were it's going to stall. the hp,torque,weight of car etc etc has alot to do with it.. with your car being 3000-3100# and not having big hp or torque numbers the converter will be very tight. here's a chart for the same converter with different hp levels this number are off one of my tech sheets that i got with a off the shelf converter. there all the same 9" advertised at 4000-4500. it would take a 8" with your power level to get it to stall were you need it..

400hp 3000-3400
500hp 3400-3800
600hp 3800-4200
700hp 4200-4600

Originally Posted by chevydrivin

Well my heads had been rebuilt and had new stock springs installed. My engine runs up to 7,000 with no problem, Ran 6,200 rpm through the traps with my 3.55 gear. Now with my 3.7 gear i hope to gain a little more rpm.

I am no exspert ,but I would do as 500 caddy suggested on the stall,1.6 rockers if you have the piston to valve clearance.
A small bore engine ,needs lift to help the shrouded valves breathe,but not so much as to get into piston to valve clearance or where you get the engine out of its power band,which in my opinion your cam and rpm are a little too much for these heads.
Take a look at this link, http://www.goingfaster.com/spo/343hp305.html ,the build is very similiar to yours and mine,the only difference is the cam you have,the link states that 343 hp at 6250,which seems to be about the rpm these heads nose dive unless mods have been done{notice how it nose dives on the dyno numbers after that rpm}.I used a comp xe 262 h in mine for a approx 300 hp,which is about the same size as the cam in the link.
All the dyno numbers on these heads I have seen on these heads show the smaller inch engines do good til around 6000 rpm,a 350 cubic inch engine drops the rpm approx 500-600 rpm for max hp.
Heres a vid of me revin mine up for the first time,needs some more tunning in this vid though.The throttle response is much better now......thnx to Denny.
http://youtube.com/watch?v=ld4vfbizOBI

Thanks Shawnlee28.I'm on this website to learn and I love learning about cars, hotrods or any. What you and 500Caddy are saying makes alot of sense,but the thing I am wondering about is that from the little I know about converters,I have been made to believe that you have to go with one that suits your powerband,this usually has a direct relation to the cam but also considers weight,motor CFM,RPM application,1/8,1/4,circle track,street toy,and other factors about the vehicle. These 'little motors that could' 283's like hi-RPM,but doesn't cam profile and breathing ability(motor,not me) determine what would be too low of stall or too high of stall? Seriously,I don't know,,, Now if it had heads,cam,other goodies and machinin,you may have trouble over converterin it,but,,,,some body explain,all I can see a 4000-5000 stall doing for this build is burning out the trans? Smack me and set me straight if I ain't gettin it.

Geesh,,,,where'd that come from?(sorry if FAYLUR seems goofy tonight,he's drinkin,Eunice) But that does convince me that 500Caddy's reasoning was better than mine cause 3500 was more than I thought,if I'm reading Denny's figures right,thats where I would begin making my power band good.Lord why don't you but me a,,,,dyno Well,foolishness aside,that makes sense.

Also on a build like this for what your building you have to look at tire size on getting you where you need to be at the top of the quarter. To get your rpms at 6,200 or whatever your peak is.
formula for HP needed at a MPH.
Constant is .00426
((.00426 x mph needed) X (mph x .00426) X (mph X .00426)) x weight of car.

100 mph and 3200 lbs is 247 HP
Which I think is close to 14 to 15 sec/qrt

with the 4.11 gear
At 6,200 rpm with a 225/70/14 (26.4 tall) tire you will be at 118 mph.
which you will not see with the HP your building.
At 5,500 rpm with that tire you would be at 103 mph.
With a 23" tall tire you could be at 103 mph and 6,200 rpm at top qrt.

the advertised stall would be 4000-5000 in a 8"-or 9". you do not have enough power and torque to make it( slip, flash, hit) much higher then 2500-2800rpm. if you were to add a 100 hp of nos the conv would stall higher. you will not over heat the trans or burn it up. i have been running small cid with 8" converters for yrs. your thinking is right if you were to have 700-800hp but with that kind of power your building custom one per app. see the problem is when one guy is running a custom that was built for his combo it may have a 10" but your not looking to spend 1000$ on one. so you have to play the what if game. i have played that game i have spent more money then i care to say. most of the time i have to send one back to have them loosen it up. don't take this wrong but you have a 291cid low compression, short stroke all killing your torque. without torque any conv will tighten up. the impeller pushes fliud through the stator to the turbin and makes the car go. (the higher the power the faster, higher the rpms the impeller spins before the stator makes the turbin move i.e stall speed. the lower the power the slower, lower rpms the impeller spins before the car moves. the only time all of it spins at the same speed is a lockup conv.) this example would be for the same conv with different power levels. a custom conv will have the right stator for your combo and takes all the guess work out.

Duh,,,ok,,,,"Mr.Hughes??? Hid in Dillons shoes,wearing his disguise?" (That was a song but you seem to know converters and since you mentioned Hughe's converters,,,,thought you might be associated,,,wellll,just jokeing.
But how 500caddy???I'm running out of air at that RPM and the converter would just be transferring torque?
edit,,,,or were you saying I need a 2500-2800?

one question to help pick a converter, Are you going to foot brake it or install a trans-brake or what?

WHAT DENNY SAID. i use neal chance convertors ONLY in cars over 800hp. but alot of companys make VERY good street conv. just i know how the hughs work as for advertised and what they will go behind a hp level, weight, tire etc etc. that's way i said to try them. if you were one of my customers i would put the 8" 4500 in there and it will work at 2500ish with the low torque your putting out.

The whole purpose is to transfer torque from motor to trans,by means of fluid pressure and will suit the bill as long as the fluid pressure matches motor torque applied,at launch or thruout the run?.Where in that process wouldn't a 2500 work? Are you saying that I could use more at the higher rpm levels,I don't know because I thought once a converter did it's thing it was constant throughout the rpm??? Cause rpm launch,with 411 gears and Oddlots brake and my cam/heads may not launch any higher.Now,I admit,once the vehicle has overcome inertia and is up in the power,I havn't a clue where the converter has gone?

faylur, your getting hung up on the rpms. a 4500rpm 8" will never see more then 2500ish with your power and torque...you don't have enough to make it go there... if you put a 10" 2500-3000 stall in your car it will not rev because again you don't have enough hp ftq to push that convertor to 2500-3000 it will be more like 1800rpms and with the extra weight the 10" will even slow it down more...

you're getting closer in understanding the fluid drive part of it. If everything is perfect, the converter should go 1 to 1 when stator speeds and drive vanes start to match rpm. This is only in theory. Most converters never really do go 1 to 1 during the run. Powerglide is the closest in doing so. You still need to also commit to foot braking it or transbrake, it will help you launch the thing with the best flash also. If you have any doubts with your setup, you get to decide whether you need as low as 2500 or as high as 3500. Something as simple as a B&M super hole shot would do your engine well.

Well,I will go off in the corner and study this one because other than the weight factor,that sounds backwards from what I have learned.Less converter gets a low torque,low power motors torque applied,but you may be right,and though I don't consider myself hardhead or un-willing to learn,your recommendation seems quite unorthodox.But you may be right

Originally Posted by nitrowarrior

you're getting closer in understanding the fluid drive part of it. If everything is perfect, the converter should go 1 to 1 when stator speeds and drive vanes start to match rpm. This is only in theory. Most converters never really do go 1 to 1 during the run. Powerglide is the closest in doing so. You still need to also commit to foot braking it or transbrake, it will help you launch the thing with the best flash also. If you have any doubts with your setup, you get to decide whether you need as low as 2500 or as high as 3500. Something as simple as a B&M super hole shot would do your engine well.

So the motor is overpowering and the converter catches up after launch? If this is correct then that explains his recommending more stall,if I am understanding you right.
This is great learning,on a subject that you don't hear much about.