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LS engine versus SBC throw down, who has the best torque below 3000, HP to HP

67K views 157 replies 14 participants last post by  Project89 
#1 ·
Started this thread to settle the debate of new to old, which engine of similar displacement has the advantage below 3000 rpm with similar HP.

Lets see who can come up with dyno graphs to support their views, I'll start...heres some 500 HP dyno numbers for a SBC.

383 from AFRs website, 195 heads 9.5:1 compression...nice street engine. Everyone has seen this kind of build before...pretty common.

Peak HP=506@6000rpm, torque=520ft/pds@4000rpm

https://www.airflowresearch.com/chevy_dyno.php

Whats important here isn't the peak HP, its the torque under 3000 rpm.

HP/torque=262/454 @3000 rpm

Next on the list is a similar LS3 built up by Crane to showcase their aftermarket cams.

LS3 x 3 – Comparing Three Performance Cams on the Engine Dyno - EngineLabs

Note the 500.9 HP version peaks at 6100 rpm with a peak torque of 488 at 4800 rpm.

More important to note the torque below 3000rpm, 238HP & 418ft/pds @3000.

This is where the SBC really shine folks...under 3000.

Alright who has a dyno sheet for an LS3 that tops that at similar HP, Im looking at you AP72.:thumbup:
 
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#117 ·
Torque converter,BTW this is way off topic!
think of a big elastic band
put a tow vehicle in front of your car,all brakes locked,,, the vehicle slowly adds tow pressure and the elastic band stretches until it finally pulls your car locked up tires and all,
mark that amount of stretch with paint on the track,,,,
thats your stall speed

Now do this exact same test again but this time instead of slowly adding power until the elastic stretches as far as it would normally then begin the tow.Put the vehicle beside the car being towed and accelerate full power until the elastic stretches(this time further because you took a running start{flare}) and the car gets launched like its in a big slingshot
The tow vehicle(engine)has a running head start,and the elastic band is trying to contract(torque converter) The towed vehicle is catching up.

A matched race converter is usually around 2500 RPM below redline.This is just a starting number,many variables will make the math a little different.IE big engine small car will be tighter that a small engine in a bigger car.
 
#118 ·
Torque peak is the rule of thumb, add some rpm to that for heavier vehicles or use of a trans brake.

There is no magic formula as each car is unique and any one converter may stall at a different rpm in a different car.

I'm really interested in this "power figure" AP has eluded too, sounds like a secret combination or multiplier of torqueXrpm which only Glidden and the high end AA fuelers use to set up their clutches.

We are through the looking glass here people...

Note to self: We need a tinfoil hat icon.:p
 
#119 ·
Good one Vinnie:thumbup: A rubber band:D I would never have thought of that!
Very simple
Bottom line is "The speed at which stall occurs with a given converter is a function of engine peak torque". There isn't any changing of PHYSICS or formulas even the best high stall convertor manufacturers say it!

Any one that wants to know what the new stall is behind a different engine this will get you close:
The K factor is the result of the observed stall speed of a converter behind the origenal engine: K = RPM / √TORQUE

RPM at which the same converter will stall with a greater torque applied to it,
RPM = K √TORQUE

When referring to "how much stall will I get from this torque converter", it means how fast (RPM) must the torque converter spin to generate enough fluid force on the turbine to overcome the resting inertia of the vehicle at wide open throttle....................................



Oh HELL I give up anyway:smash::smash::smash::DLOL

Jester:D
 
#120 ·
Not that any of this has anything to do with the original post.:D

We need new threads for each HP category, big bore and small bore strokers in its own subcategory.

Votes on which categories to create?

650-400HP? Kinda covers the street category while going into the race a little bit.

Since no one builds such low HP LS engines, I take it we won't have any of them in there.:p
 
#121 · (Edited)
:thumbup: This thread is actually good and more of a Lounge thread With a little leeway on subjects with still really good info mixed in !!:) for anyone interested:rolleyes:
I had a good post in reply to the flat tappet cam I selected for my 440 but didn't post it because of this Torque debate LOL I have it saved and asked Vinny if I should post or not LOL I had doubts because it may take this THROW DOWN in a whole new direction and PHYSICS LESSONS>>>> ROTFLMAO :D

Jester
 
#122 ·
Ok, here's an example. it's an LS engine, so its more related, and its a cheap turbo build taken off this page:

594HP 5.3L Gen III Small Block for $3,252 - Hot Rod Magazine All Pages

DYNO RESULTS

5.3L at 8 psi 5.3L at 12 psi 5.3L w/LS6 cam at 12 psi
RPM HP TQ HP TQ HP TQ
4,100 433 555 444 569 457 585
4,200 446 558 458 572 468 585
4,300 459 560 470 574 480 587
4,400 470 561 481 575 492 587
4,500 481 562 492 574 502
585
4,600 492 561 502 573 511 584
4,700 502 561 512 572 522 584
4,800 511 559 521 570 535 585
4,900 518 555 528 566 548 587
5,000 524 550 536 563 560 588
5,100 528 544 543 560 569 586
5,200 530 536 548 554 575 581
5,300 532 527 550 545 580 575
5,400 531 516 550 535 585 569
5,500 528 504 547 522 589 563
5,600 524 491 542 508 594 557


So... What is the ideal match for this car in stall and gearing assuming it's a 3,000 lb camaro, use the middle dyno result for 12psi?
 
#124 ·
Now AP is going have fits with this post.c.i. to c.i. compere-sons of first gen's sbc's to lsx engines in real street racing,hands down the first gen's 60's are better by a huge margin.The off idle torque potential of first gen's is substantially better.Take the same elements applied to a first gen say electronic induction like a Edelbrock Pro flow or turbo's at 12 psi with matching t/c stall and everytime the first gen will over shadow the lsx engines.To be totally fair you have to have reliable test results doing the same mods to both style engines.
 
#125 · (Edited)
I thought it was supposed to be a N.A. engine not BOOSTED!! boosted engines generally don't need aggressive stall converter rpm or gear ratios on a boosted car !! Since normally aspirated engines generally make their peak torque and horsepower at a higher rpm level, and in a narrower rpm band than a boosted !!! Boosted cars are very hard to predict when installing a high stall converter without 2 or 3 to track test! A suggested convertor from power curves is unpredictable, A suggested converter can kill boosted power They aren't picked by the same process as naturally aspirated engines!!!
Jester
 
#126 · (Edited)
If Naturally aspirated you want a converter that stalls at an RPM that lets the car leave as hard as possible without breaking traction, then flashes up to a speed where the engine is getting into the fat part of the power curve. A turbo car only needs a converter that’s a little “looser” in true stall speed, to let it get up on boost as you use your foot brake stall or t. lock, but tighter (lower RPM) in flash stall to get the car rolling off the line before the power from the turbo really hits !!!! If you guys use High Flash stall converters for N.A.cars on boosted cars your wasting HP!

Jester

Forgot to mention this: Nitrous is not Boost!! Nitrous cars are an example, where the engine may not be making very much torque at all sitting there on the trans brake, compared to how hard it hits when the first stage of nitrous comes on. So those convertors are easyer to match to the engine Torque but still a little different then N.A. engines!!!
 
#128 · (Edited)
You take all necessary info for an estimate on Brake stall. and then figure your needed FLASH stall, then have a converter built, with a free adjustment if needed or you buy a recommended converter over the counter and hope it works (because it needs testing to make sure the flash stall you need is right)!!!
Your rear end gear ratio
How tall your tires are
How heavy your car is + additional wght.
How big your engine is
How high you plan to rev it
The specs of your cam
And the use of ,,,,,,,,,,,,,,,,,,,,,,,,,,,,"BOOST !!!!"
Elevation & temp and spool up rpm of the turbo

Don't you guys consider FLASH stall in your cars building plan?? Or is advertized brake stall your main concern? Flash stall is very important to me !!! Not just my staging stall (BRAKE STALL) but my flash stall too especially on boosted or nitrous cars!!! :confused::confused:

Jester
 
#130 ·
So the correct stall speed according to you is 4500rpm?

Exactly 300rpm above the first torque peak which is with a transbrake?

Doesn't this coincide exactly with what I posted earlier?

In this torque curve you have provided, where is this "power" you eluded to previously. Apparently proper selection of torque converters depends on the "max power" figure and where it is located.

Can you explain why the correct torque converter should not be higher than the first torque peak, perhaps the second peak instead?

Perhaps a more conventional torque curve could be used to explain this "theory" better, this boosted application is not a simple enough curve to explain it.

Are the actual track results from testing available to prove this theory or do we just have to take your word for it? You have raised more questions than answered with this example and haven't explained it?

C'mon dude!:confused:
 
#131 · (Edited)
Where did you get the trans. gear ratios to get shift points? Whats Max RPM and red line, are your shift points over red line or under? At what Minimum RPM is the Turbo reaching boost on that application? Maybe I missed some pages in the article or something ? I only have one short page with pics and keep reading the article over to see what I missed that you got out of it! Scratching my head all day:confused:

Are using that article and an actual car build that you know to get that info? And to fill in the blanks not in the article? You said : " use only 5 gears of that 6 speed trans"
I can't find the 6 speed trans your talking about Where is it posted? What kind Truck ,car, stock, racing trans, let alone trans ratios 1,2( 2-3 shift is quite a drop)??,3,4,5,to get shift points?


Jester
 
#132 ·
Chris I chose the TCI 6 speed as what I would use and a 3500 converter
the gears are,1)2.97:1 2) 2.31:1 3) 1.57:1 4) 1.18:1 5) 1:1 6) .75:1

I only went 3500 stall because the engine was making enough torque with almost 12:1 over all first gear to put the car skyward,any more converter and you could blow the tires off or unload the suspension with the back bumper,
Chris,you are more qualified to explain how to make a car hook using wheelie bars,and the pitfalls,,,
 
#134 · (Edited)
Why the 6 speed Vinnie? And the your 3500 B.stall is closer to my choice too I would choose a 3000 B.stall and around 6000 flash for that tubo car. With that much low end torque, and the turbo would have to be spooled up to boost by then!

I think that engine in APs 3000# car with that much torque at the bottom end with that 3.90 (Vinnies) gear and APs short tires and I'll Guess radial slicks (the width we don't know or tire pressures)Real word considerations not Hypothetical!!! and a 4500 stall would BLOW the tires OFF Or The Engine is a DOG or there's loss of HP through the drive train. and it only looks good on paper! I never saw a HYPOTHETICAL (LOUSY) 2nd to 3rd shift in my life 500 rpm higher then all the other shift points ROTFLMAO when I saw that, the shift points are all over the board! If that's the programmable trans LOL I would replace it or get a good mechanic to look at the rest of the components behind that engine to see whats creating the drag from 2nd to 3rd at that speed LOL!!! And a 4th hypothetical 100 rpm less shift:confused: WHATS THAT ?:confused: I just keep scratching my head:confused:

Hypothetical calculations don't usually have bad shift points, or other flaws included in them They are hypothetical for optimal performance, and then Real word specs are from testing and actual runs. And the only way to test a Convertor is to take a few to the track of different stalls and see which stall is closest to produce the best performance in real life, or you will never know with just buying one over the counter by a recommendation! you spend the money and get a custom convertor test it at the strip and then get it adjusted usually you get one free adjustment from reputable builders!!

By the way stall CHANGES on cars depending on altitude and temp. If that needs explaining to you guys that live up high your in trouble LOL Ask!

None of this matters on the street LOL so all I've written is mute to street builders and most weekend warriors don't have the cash anyway and don't have any idea how much power they could gain per dollar spent for a "RIGHT" convertor!! On the street a 10th in time or greater isn't noticed !!!

Save on a cheap over the counter Conv. and waste all the big money you put in the engine and drive train !

I would install LADDER bars LOL:thumbup:

Jester
 
#135 ·
The shift points change because the gear spread isn't equal. But then again there appears to be a lot you don't understand. Btw if you look at the rpm my proposed setup would be running it it keeps it centered about your peak- surely you can understand the point in that.
 
#136 ·
I understand your choice!

I understand everything except: Your B.STALL convertor choice and Seems to me your eyes on the tachometer most of your pass worrying if you can hit those shift points or you have 3 shift lights or the trans is programmable! Why use a TRANS. with a crappy gear spread like that unless its what is actually being used in a real car your borrowing data from ??? Is this a real cars DATA ?:confused: Yours? or someone elses?:confused:

I looked all over the internet for the article you posteds engines data that wasn't in the "cheap build" article, A Dyno graph, what RPM the turbo spooled up ,etc or anything else to answer some questions to form an opinion on the question you asked about stall recommendations! A hypothetical car with the engine from the article !

Jester
 
#137 ·
The trans selection was vinnies. I would opt for a cheaper th350 but that choice will work. He already posted the gear spread.

The article I posted has the build and dyno graph. It's a turbo'd stock 5.3l, that's it.

Btw there is no cheap trans with a good gear spread- unfortunately. The th350 has it's own problems.
 
#138 · (Edited)
I read the article!!!
I never mentioned a cheep trans? I wouldn't use a cheap trans. But that would be my choice to each his own! I don' see why with this being hypothetical Vinnie would use a badly geared cheap trans with erratic shift points ? The " 594 Horsepower For $3,252" and a junk yard trans ? TCI 6 speeds aren't cheep some are over $5,000

I saw no Dyno graph just a written comparison starting at 4,100 433 555 444 569 457 585, and ending at 5,600 524 491 542 508 594 557! Sorry I never saw a graph! unless 5600 RPM Is the Max and 4100 was the beginning when the turbo began its boost?? If you can post a corrected graph please do so. I'm interested in HP off Idle till turbo spooled up to see performance bellow 4100 RPM???? In its cruising ranges? and I need max RPM crossing the 14 mile to figure at 1 to 1 final ratio to get ET or top speed or is 5600 max! At 5600 RPM 542# torque that car should be still be accelerating? And RPM still accelerating is more speed and I have questions of 1/4 mile actual capable speed and time??:confused:

I Didn't see Vinnies gear spread on the trans he used or that it was a cheap trans I missed that I guess? I'll take your word on that I'm not going back to look it up :thumbup:

Jester
 
#140 ·
I said a cheap trans because a) I'm cheap and b) for the power made that engine is pretty cheap. Th350s are very common because they are cheap and work. The trans Bonnie found is nice but more than I'd spend.

Also, if you're launching off a trans break then I'd get a flash stall as close to your break stall as possible- it'll transfer power better than a higher flash. Also, I assumed the dyno carries out to 6500 in a symmetric fashion, which may or may not be the case so you may need to move your shift points a little.

Wether or not you can get it to hook is a different story- and yes that will need some work.
 
#141 · (Edited)
1500 rpm flash over 4500 B. stall isn't that much for Turbo boosted cars Ive built! Using your specs! Now my 3000 B.stall I would try a flash of 6000 on it, its Too much for a Roots blower Boost yes:mwink: But we don't know Max RPM for the turbo car and I would use Vinnies tire size bias belted wrinkle walls or taller, and change gearing accordingly (like you said) with (if I had too) slappers bottomed out with stiff springs & shocks, 90/10s on the front snubbers removed, But I would much better like Ladder bars! If the tires blow away I would make adjustments and with my flash that high they might, but its easier adjusting flash down then guessing and adjusting flash up! If you blow the tires off you know its too high, but if flash is too low you won't know it.
I know I should be more conservative on my flash I don't know that turbo, or the missing Dyno numbers but that would be my starting point

I like bigger bias wrinkle wall slicks, steeper gear, stiffer suspension (Ladder bars, rear ends snubbed etc) and a higher flash to put the reciprocating energy building in the flex plate to the tires and after the moment of launch and flash drops off the power should be about where its needed at the first shift point! Unless you have to shift while the wheels are still in the air!:mwink: But testing would be needed to know for sure! Needed flash is debatable till real life steps in. Like you say getting it to hook !!

Nothing wrong with a budget trans, I might drop the flash RPM down worrying about the trans holding up to the flash (multiplied torque) applied to it.

My last post should also say " TCI 6 speeds are over $5,000 " Man:pain: I'm having a bad day typing what I'm thinking LOL:smash::smash::smash: I proof read these posts too LOL:rolleyes:


Jester
 
#142 ·
I called TCI last year inquiring about the 6 speed auto.I also asked about different gear ratios as the ratios offered would work well in anything I could come up with? Maybe a 283 in a street car could make fools of some exotics with 5.0 gears and drag radials. The close gearing would be fine in a road race car,,,not sure what road race car needs an automatic?

Bottom line was I wanted more than 3 gears with a 5500 RPM peak power marker. If that engine made peak power at 7500 RPM I would have used a glide.
It would be an expensive turbo 350 to take the continuous torque from a turbo charged engine
 
#144 ·
I went to Liberty 4 speeds no clutch after 1st gear, and clutchless 5 speeds! thats because I tore so many bell housings off my automatics in the early years:pain:, 4 speed super hydros, powerglides, 350ts, 400ts, torqueflites all not cheep transes:nono: I didn't crack every trans I used LOL just once and a while scatterd over the years, I Tore one off on Woodward Ave. and trans fluid flew under the car and on the tires and I lost control (almost died that night racing a blown model "A") Stupid:nono:. Never could figure out why they were cracking and tearing off! Well I finally found out at Deroit Dragway a couple of weeks later during a chat session in the pits with Chet Elkins a local trans guy and FX racer!

Well I see a few guys now buying transes with a high hp ratings coming to me and asking why they are cracked? Well the transes 1000 HP rateing is a rating not to the engine but to engine Horse power applied to the cars wght. Like being Rated to Approximately "1500 Horsepower at 2500 Pounds of car wght" but I guess most of you already know that ! Well I didn't Know that till I was in my 30's I thought I knew it all after racing for years and I was on pit crew duty for a lot of cars but not a trans guy then! And the topic never came into pit chat !

I was running a heavy car and with the high flash applied to it off the line ( was even multiplying) the wght applied to the bell housing, Hair line stress cracking them, run after run not even thinking of pulling them and checking them till the stress cracks finally turned into a huge crack or sheared off the bells!!

I have a Summit High rated turbo 400 B&M hair line cracked 5 inches into the bell close to the main body very hard to see the crack! Its setting in my garage cracked from 1 run causing a vibration when staging for the 2nd in a 77 Corvette Destroked 350 to 302 475 Hp 9500 red line ( not that much power to the trans) at a local airport 1/4 mile drags ! :pain: Ive taken almost 500# off that car now!!!!

Maybe someone out there using automatics that doesn't Know will be helped by this post:thumbup: Especially guys running stock or cheep transes :thumbup:

Jester
 
#146 · (Edited)
I'm bored : so I'll steal the thread for a moment, If you don't want it on here 4Jaw have it removed :thumbup: It won't bother me at all LOL:D

Bob Larson & Joe Liberty were my competition in the early years sponsored by Mayfair Auto parts, Bob passed 2 years ago Joe retired a while back onother friend of mine, all of us from Down river, another friend Detroit area AKA Chet, or DAN, Dana was his real name he hated that Died in a race crash at Ubly Dragway in the late 60s:(!! 3 innovators ones life cut short Joe started Liberty Gears and Bob started Larson engineering Both way ahead of their times!

Joe & Bobs Gasser enlarge pictured bellow notice the header 2 primary tubes from each head joining into 1 collector and the same with the other header The Dyno showed huge gains over the 4 from one head into 1 collector that is a normal design This is in the 60s!!! I had a house fire and lost all my own pics in the 70s so I had to post these:( and notice the solid frame in one pic and the holes in the frame in the second!

http://www.hotrodders.com/forum/attachment.php?attachmentid=124698&stc=1&d=1393531236

I went to work for Bob in the 70s in the engineering and design department and welding with my friend Packy Who drove the "Pack Rat" We learned a lot there and left to further our careers on friendly terms:thumbup:

pics of Bobs 1950s show car! Go to this site The Hot Rods of Dearborn: The Untold Stories

http://www.hotrodders.com/forum/attachment.php?attachmentid=124706&stc=1&d=1393531713

The 3rd pic is Chets A/FX car it Rolled part way into a pass and took Chet from his family and friends but left me with great memorys from my youth:thumbup:

http://www.hotrodders.com/forum/attachment.php?attachmentid=124714&stc=1&d=1393532178

You young guys that missed that you missed a great time in HP history Now the back yard garage innovations are far and few but then Ideas and fabricating was all over the map and we old farts are dieing out fast I still race a bit not running the circuit any more just Local tracks or a nostalgia drags once every few years or at the local air port (Gladwin Zettel Memorial Airport)4 weekends a year that has clocked 1/4 & 1/8 mile drags and tune up runs, and the pit chat I see today is what to buy and whats it cost!

I miss the old times:thumbup: and love old school drags:mwink:

All thats needed is to talk to the airport in your community and the city to set up something like this:mwink:




98 % of these cars are local all street driven Many are my customers running my engines



Jester:welcome:
 

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#149 ·
You worry too much, the thread has taken a different direction and thats OK by me.

I enjoy reading everyones posts, don't stop now!;)
 
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