Has anybody ever ran a 3.25" or 3.5" crank in a big block to get one to rpm higher???

I read somewhere that years ago, 348 and 409 cranks were ran in big blocks because of cubic inch rules or something like that.

Any body done it???, and if so, how did the engine run??? pdq67

Ok PDQ here goes,

I saw your post over on the other slot under Jeffro and you said no one would answer your stroker question.

You may not like my answer but here it is,the age old answer is there is no substitute for cubic inches,and this still holds true.

I think you would like to shorten the stroke to make the BB rpm quicker, my question is why steal the awsome torque from the BB. Yes it may rpm quicker but how are you going to blow away the small blocks on the big end of the 1/4 with rpm's and no torque.

If you want the BB to go more rpm's there is a limit because of bob weight,in other words the size of all the moving parts.

You can turn a BB just as tight as most SB's if you have the mega bucks for the right lower end parts.

I hope this don't sound smart or any thing it's just my opinion.

Larry

Hello ! I agree with Larry 100 %!
how ever i had a 1969 vette with 5 speed richmond and modified LS 7 I personally like high rev engines too,so i carefully blueprinted and balanced all and add manley steelrods . then i used victor manifold and crane custom grind roller cam it rev really well 7500 (powerband 3500-7500) but i havent had the 5 speed with extra low 1-2-3 gear it would not be such a fun to drive since it didnt had good lowend torque. (and it needed 11,5:1 comp ratio!)
if you want engine wich revs go with smallblock,its easy to built 9000 rpm smallblock if you have right parts!

Joni

Larry, Larry,

NO, there are no smart a--ed answers. I'm just asking if anybody ever ran a short stroke big block due to cubic inch restrictions because of some class. And if so, how did it run???

I'm wondering if the benefits of the big block splayed valve head is that much better than the wedge designed small block head.

And I know that it takes alota money to make a big block survive at 7500+ rpm's and way above because everything is bigger and heavier which means stuff has to be stronger and lighter(if it will stand the high rpm pounding).

This is why I'm a little miffed at Chevy High Performance for not finishing their head flow test by including the buick 10 degree, the splayed valve and the SB2 heads.

I just wonder what a 4.25" to 4.75" bore/3.25" to 3.5" stroke big block would be like if it was made ratio wise like a full house 302" small block, and I don't mean estimated per my copy of Dyno2000.

I did run a 4.25 bore/3.25 stroke 369" engine through it and came up with 592hp at 7500rpm with only the valve sizes automatically calculated.

A 496", 4.75 bore/ 3.5 stroke one came out at 684hp at 6500rpm. Neither engine has been maxxed out with respect to a balanced design due to the larger cubic inches over the 302.

I would really like to hear from somebody that has ran a big block that would wrap like a 302 just to get their opinion. And thats all. Thanks for the come back. pdq67

Hey PDQ,

Say one does get this combo perfected,and say short stroke needs low gears who will be able to shift gears fast enough to keep up with this bad boy. Just Kidding.

I do see now from your last post what your question is,and I'll quit jacking around now and wate with you to see if anyone has actually tried this.

Larry

348/409 crankshafts were commonly used in big block engines to get rpms out of them when the Pro-Stock class was just getting started. One proponent of doing this was Reher-Morrison, in Texas, they did a lot of them.

RPM levels were reported to be near 9,500, and favored the latest head porting of the late Lee Sheperd. They won a lot of races with those de-stroker engines.

Although some here are correct in the assumption that there is nothing like cubic inches for performance, there have been very successful exceptions to the rule. Remember, however, the shorter stroke engines require loads more rpms to make power, at the serious sacrifice of lower rpm torque/power.

My cousin used to race in E-gas in the mid to late '60's. He held the E-gas national 1/4 mile time for a while, having won the Winternationals in, I think, about '65.

He's a SB guy.

He told me the other day that he has a 300 inch motor in his basement, ready to go, that will turn about 11,000+ RPM and put out about 700-800 HP on fuel injection.

Now, that's a revin' motor. I asked him how on earth does a push rod V8 motor ever manage to crank 11,000+ RPM??? Like, how could all that heavy metal, being operated by some long, slender rod, not just turn into a horrendous, smashing, crashing mess in a matter of seconds. My cousin, Gene, says it's all in how you build em'. He learned how to build them the hard way, by blowing up a lot of hardware. He says the secret is very careful blueprinting.

I'm trying to talk him into giving me the motor for my '72 240Z. Nothin' like a Chevy mouse-powered rice burner to make you feel like an all-American hot roddin' boy! And I know, if I got it to hook, that it would simply obliterate any turbo Eclipse or Honda Civic.

Anyway, I just can't imagine a BB ever going 11,000+ RPM, and neither can my cousin Gene. That's why he always raced SB motors. Of course, the tradeoff is that the high rev SB will not make good power at low RPM's and just won't have the monster torque that a big crank behind a big piston will produce.

But, that's all been said many times before.

Personally, I'm running a 396 BB in my '69 Camaro and I think it's great for the street... and I could also use it to pull stumps on the weekend if need be.

Just thought you would like to hear a little drag racing history and some additional thoughts on SB versus BB motors.

Jim

I suppose the engine internal components would be made out of that exotic sh-t called "unobtainium".

I've heard of a company that was trying to run a real live "plastic" engine at Indy.
Seems as though the crank was hand laid up carbon fiber/plastic matrix, as was the rods. I'm not too sure it even used oil or water or not. It might have even had ceramic valves, valve springs, pistons and combustion chamber lining to stand the heat of combustion.

Has anybody heard of this stuff???

Anyway, I would think that maybe a titanium crank/rod rotating assembly would lighten it up enough to be able to stand running above 10,000rpm, but I don't know what the fatigue life is for Ti.

Isn't Crower selling some super light weight magnetic rods??

Plus, a 4.75" bore/3.5" stroke big block would have 496 cubic inches so it is "big" when compared to a 302.

This is an interesting topic. Thanks Iman and all for chatting. pdq67

Even overhead cam engines, racing type don't enjoy total control from valve springs.

Formula one engines are limited to 10 cylinders, normally aspirated, make upwards of 1,200 horsepower, and have an 11th cylinder made into the block, for an air compressor, for the valve train. The valves do have very weak coil spring sets and are just there to keep the valve from staying open when the engine is being started. air pressure is used to control the valves after the engine starts, stored in a tank in the chassis pod.

RPM levels for almost all the formula one engines is between 16,000 to 17,500.

At the last F-1 race, a competitor had to go into the pits for a shot of air pressure into the storage tank as the on-board compressor had failed to keep up with the demand.

Modern day valve springs aren't up to the rpm levels we use in some racing, and Pro-Stock is a good example. The average big block Chevy type Pro-Stocker engine runs just 7 seconds at a time, uses 11,000 rpms, and has an average of 1.100 valve lift. Special titanium springs are used, cost $1,700.00 a set of 16, and get changed after between 7 and 10 runs. Individual springs get changed every run if they get sacked early, and the entire set is replaced at the 7 to 10 run level. Springs have 3 to 4 coils, depending on just who made them. Life isn't great.

Lets try a 4.75"bore/3.5" stroke 496 bbc with
14.0 to 1CR, fully ported and polished 2.67"/2.17" valve heads, 1500cfm tunnel ram, large stepped headers, solid roller, .800"/.800", 270/276 duration at .050", on 112/108 centers

How about 1221hp at 9500rpm/822t at 6500rpm.

I'm not saying that this combination can be built, but it sure does put out some power.
Add a 5.3" crank and come up with 751 cubic inches and now you get 1149hp at 6500rpm/1032t at 5000rpm. Torque came up a heck of a bunch, while power came down in the street range, interesting isn't it. pdq67

With a smaller bore size, the way they were built as early Pro-Stockers were, with the 409 shorter stroke crankshafts, they made about 1050/1060 hp on average, and ran very well. Call Reher-Morrison and ask.

That's the picture, Iman. R/M just made some big block Z-28 type engines, didn't they?? pdq67

Hey there Ignition man. Back I see, Good to see, how are you on this fine day? And now on this short stroke big block thing, where did those 2.67/2.17 valve heads come from. The bore would have top be at least 5" to acomadate all that, and even then the shrouding would be a an issue. Anyway, Like previously stated, That would take away all that they have going for them by removing the low end those big motors make. And all that weight, those things are over 150 lbs more on the nose than a small block. And untill you get into the mid 8's or the Outlaw Super Street and beyond, A small block is going to be the faster motors anyway. There is one advantage to the big motors though, they do make some big flowing heads for them. A friend tried running a 410" motor for a bit. The cylinder heads flow way more than is possible with a small block, even the buick or pontiac dart heads, and other 15 degree pieces out there. It looked good on the board and it was fast, but it just wasn't there. The small block 414's and 27's are powerful motors. 1400hp plus on the bottle is a lot of fun. Just wanted to add my thoughts Galen

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S/B Chevy Lover
67 Camaro street car
10:50's @ 128 on motor w/383 cid
79 Z28 w/383 9.1:1 3.73:1 Restoring stock apearance
13:40's @ 101 stock exh.& intake& Qjet
smog legal
Camaro Lover

I do know that the last of Shepherd's heads with the 409 crank BB engines had 2.300 intake valves, and furnace brazed places, altered guide paths, very relieved valve cutaways.

RPMs were the order of the day, and they used 5 speed transmissions, instead of the 4 speeds they mostly use today. The short strokers made their torque in the upper rpm ranges as well.

As far as no low end torque, they always left against the rev limiter, so getting rpms wasn't a real serious problem. With the extra gear, the torque was in the right place for the mechanical advantage of all the different gear ratios.

After NHRA opened the cubic inch regs to the currect 500 cu/in limit, the racers went back to longer stroke setups, and lower rpm torque setups.

Galen,
I came up with the valve sizes from Dyno2000. Plus I mentioned that these combo's may not be buildable.

I would love to see two identical engines built. The first, a full house 302 Z with the BEST "aluminum stock wedge heads" made. No nothing done to them, period.
The second engine would be the first one EXCEPT for a pair of small block style big block aluminum heads with the same sized valves and rocker arm ratio as the wedge heads. Nothing, and I mean nothing different otherwise between the two engines except for timing optimized for each engines combo.
Dyno both and then give us a spreadsheet with the runs hp and t values. This is what I keep talking about with Chevy High Performance not finishing the head test.
I would also like to see the buick 10 degree and the SB2 heads ran on this engine combo. This would put to sleep the big block/small block B.S. differences forever (or until the next time). pdq67

PS. And I do realize the differences in weight, but that can be remedied by the new ZL-1 aluminum block except for its cost.

Larry you are the man....we must heve went to the same school
pdq67.....its a pie in the sky
just look at it that way.....if the chevy 302
was that great of a combo every body whould have had it in there car...........joe

tzagi,

Lets look at this another way. Last night I was at Walmarts and thumbed through a rice-burner magazine. Seems there's some little bitty imports that are making 550+ hp. These suckers only weigh like a ton+. And oh my God, they take them to their version of an old fashion drag-race. Now lets have your average First Gen. 450hp/383 pull up beside one of these pocket rocket's and see whose laughing at the other end of the strip. H-ll, the 383 can even use a 150hp hit of squeeze to even things up.

If I can build a short stroke big block that makes max power say in the 7500/8000rpm range, gear it right and let it go. I will probably beat whatevers beside me that is a comparable engine. Not some maxed out strip only thing. Now before I start a fight, I'm trying to factor in revibility, the short stroke engine will flat rpm faster and get down the track faster.

Anyway, it might be pie in the sky, but its fun to discuss.

By the way, didn't Grumpy Jenkins play h-ll with alota cars with a small block vega using principals like this once, way back when??? Iman already mentioned R,S&M.

I may be coming into this a little late but here's my nickel's worth.
I hear this snivelling about Big Block versus Small Block all the time and what if's as well. The truth is that, there is no substitute for BIG! The HEMI ruled Superstock in Da' Grump's day and even he switched when winning became important.Torque pushes the car down the track, scientific fact!! High winding motors require exotic parts to survive(ie LIGHT)and that don't help torque.But a small big block is still faster than a big small block and cheaper and easier to maintain.
I quess it's hard to hide the fact that I have a BBC camaro, huh?

MY10secSS,

Your are right about the Elephant, BUT, the last one out the door was going to be the "ball-stud" just like a Rat. But Mopar had problems.

Torque does rule and the bigger, the more of it. I'm trying to say that 500 inches of big-bore/short-stroke will have a good amount of low end torque BECAUSE it's 500 inches. Plus it will wrap like a small block. Thats all. Set the limits at 7500rpm and cam and gear accordingly and hold on.

Check how much torque the old 348 and 409 put out for short stroke engines?? And they were big blocks, just not modern ones. This is fun, toooo!!! pdq67

I'm not finished yet, GM didn't kill big bore short stroke engines because of lack of torque. They killed them because they pollute more due to the inefficiencies of the primative combustion chambers back then, even if they were state of the art for their time. pdq67

I was watching the drags on ESPN today, in the shop, and they showed one of the "new" Pro-Stock Hemi's with its valve cover off. It ain't like older Hemi heads.

Valve arrangement was from front to back, I-E-E-I-I-E-E-I. and the top rockers had pushrods that were above the fulcrums, not below them. The intake valves were almost on the middle line of the heads, not angled twords the top of the head, like older Elephant heads. Also, the heads had individual rocker shafts and pedistals for each valve, like a Boss 429 engine, no multiple rockers per long shaft.

Plugs were still in the center of the heads, like the older design, the the rest of it was new.

They didn't show one of the heads of the engine, just a 10 second look at one on an engine with the rocker cover off. Wish I'd have taped it.

Very interesting. Mopar had a ball stud Hemi they never did anything with, pics were in one of the Pteresen pubs years back, and it looked like that, only with different rockers.

A short stroke big block is great. the 427 is probably the greatest engine chevy has ever made, good torque and excellent revving abilities chevy has poured millions of dollars into the technology behind todays small blocks and I would put my money on a ZL1 427 anyday. just imagine if they would put all that technology into a BB. An all alluminum 32 valve tune port injected 427 or even better use a 4.5 bore for 478 cubic inches.

These forums are great. I am a Drag Boat racer myself and would like to invite all you guys to visit our forums at dragboatracing.com

[This message has been edited by MrDixie (edited 05-28-2001).]

I must have been out to lunch on this one. I thought Chevy Pro Stock motors WERE big bore-short stroke motors. I still do, but maybe I'm wrong.
They do rev them way past 7500 and leave full throttle (against the limiter). I was under the impression that they made something on the order of 1200 HP and around 900 lbs. of torque with a 500 C.I. motor (NHRA). I was also under the impression that they accomplished this using very thought out cam timing and cylinder head and intake runner configurations.
Oh well. I won't be building one in the next week or two anyway.

I must have been out to lunch on this one. I thought Chevy Pro Stock motors WERE big bore-short stroke motors. I still do, but maybe I'm wrong.
They do rev them way past 7500 and leave full throttle (against the limiter). I was under the impression that they made something on the order of 1200 HP and around 900 lbs. of torque with a 500 C.I. motor (NHRA). I was also under the impression that they accomplished this using very thought out cam timing and cylinder head and intake runner configurations.
Oh well. I won't be building one in the next week or two anyway.

Someone is using my name in the posts..

My two cents is this, I ran some computer simulations with a 4.50 bore 3.76 stroke compared to the standard 4.00 stroke and the short motor made BETTER torque (higher average) over the entire rpm band. I run a 439 long rod motor and am extremely pleased with the performance.

A magazine (HOT ROD?)did a comparison between small and big motors of the same cubic inch and the big motor beat out the little one on the dyno and the track, why, because the heads flowed better and the torque was higher over the entire range.

I'll throw my 2 cents in since I currently run a short stroke bbc. Mine is a 4.280 bore, with a 3.600" stroke and a 6.500" long aluminum rod. When I bought this engine it was in a 2500 lb S/G chassis car that ran 9 teens in the 1/4 mile. The final cubic inch is 414. The heads were fully ported 990's with a Victor 454R intake, a Pro-Systems 1100 cfm Dominator, and a .712 lift, 272/278 @ .050 roller cam. This thing in my 3650 lb car was a flat out dog. I neglected to see at what rpm the torque curve began...which was about 5500 rpm. I had to spin the thing to 7800 rpm to go anywhere...it flat out would not 60' since I footbrake race, plus it bogged on every shift as the engine came below the converter stall after the shift.

Over this past winter I swapped the entire induction for 781 oval port heads, Victor Jr intake, 4150 carb, and a much smaller .653/.660 lift, 248/254 @ .050 roller cam. The change was impressive as the port velocity & torque improved and the 60's picked up to 1.56 from the previous 1.74's (no spin either). All this was in an attempt to try and correct for the fact that the short stroke bottom end could not produce enough torque to get all that weight moving from a dead stop, plus have torque to recover from the rpm drop on each shift.

Unless you have specific rules to meet with lbs/cu, I would never consider a short stroke bbc to anyone...it's simply wasted money, for less performance.

BTW, the best this small bbc has run to date is 11.12 @ 122 mph, with a 1.56 60' through the mufflers on 10.5" slicks, bolt-on suspension upgrades, footbrake launch, and a much lower 6900 rpm shift point (10.5 to 1 compression).

Anyone want to trade a high dollar "exotic" short stroke bbc shortblock for a run-of-the-mill 468? lol

Also, high rpm buzz motors get old real quick...you just drive the thing wondering what part will give up first??? rods? pushrods? rockers? springs?

A strong built 468 can easily put a 3500 lb car into the mid/low 10's and only need to rev to 6000 or 6500 rpm and live for a couple hundred passes very reliably.
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Malibu Muscle Racing (http://www.MalibuMuscle.cjb.net)
79 Malibu
414 ci BBC (4.280" x 3.600")
11.13 @ 121.8 mph, 1.56 60'
3650 lbs.

[This message has been edited by Slowazzbu (edited 05-29-2001).]

[This message has been edited by Slowazzbu (edited 05-29-2001).]

How about a 454 smallblock? HE HE http://www.camaros.net/forum/smile.gif
It's possible.

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1984 4X4 s-10. Soon to have 327 v-8, 3.73 700r-4 with shift kit and anti kickdown valving.

In Drag Boats the pro Gassers which are very simular to prostock I believe(500 cid naturally aspirated gasoline 2 valves per cylinder) utilize the short stroke big bore theory. It takes a lot more torque to move a boat through the 1/4 in 7.5 seconds than it does a car and they usualy spin them around 8500 rpm and make 1000 to 1200 horsepower.

i would go ahead and build a short stroker. when the day arises i plan on using a 502 block and getting a 3.76 inch stroke in it. the reason is the higher reving capabilites.street cars really don't need 500 lbs of torque at 2000 rpm because you'll never hook it up so why not shift it all up the rpm band to make it more drivable.

slowazzbu , was you trying to run that poor motor through the mufflers before you replaced parts?on a high trung motor mufflers kill'em. unless you have the exghaust perfectly designed with no back pressure(which is posible),that motor had no chance. but you did manage to pull more usable power out of it with the parts change,good job.

Yes that was thtough mufflers, but not your street or chambered high restriction mufflers. The mufflers run were both 3" Dynomax Bullet & 3" Straightline Performance race mufflers, both a straight thru design.

The rectangular port initial combination was not lacking in top end high rpm performance or power. That combination lacked throttle response, low/mid range torque, 60's, not enough stall speed, not enough gear, etc., etc. I think the mufflers actually helped by providing torque that the engines inherant design lacked.

The new oval port combination is running basically the same ET's as the older high rpm combo, but is 60'ing a tenth and a half quicker due to much improved low/mid range power...also at a milder user friendly rpm range of 7000 and below.

I am going to be changing to a more efficient converter soon in hopes of picking up a little more ET as my old one was slipping 12 to 14%. Tests with a borrowed 9" lower stall converter provided a .16 in ET improvement, plus 3 or 4 mph. A stall matched converter should provide even a little more improvement.

Given all the troubles of trying to get a short stroke bbc to work in a "heavy" street type car, I highly recommend anyone to spend their money on a mild, yet solid built 468 and they can easily run mid/low 10's in a 3500 lb car spinning less than 6500 rpm...and have the engine last much, much longer.

BTW, I plan to test this weekend with the exhaust removed...given this engine is "only" in the 550-580 hp range, I doubt the mufflers wouldslow it down much, if any...we'll see.
------------------
Malibu Muscle Racing (http://www.MalibuMuscle.cjb.net)
79 Malibu
414 ci BBC (4.280" x 3.600")
11.13 @ 121.8 mph, 1.56 60'
3650 lbs.

[This message has been edited by Slowazzbu (edited 06-01-2001).]

slowazzbu what gear ratio are you running. That is not that much of a change in the stroke the long rods are hurting you more than the 3.60 stroke. I ran a 3.76 stroke stock length rod motor in a 55chev wagon that weighted 3860 lbs without me and it stormed. The cam was 280-286 at .050 and I ran 5.13 gears. I think if you changed the gears it would work.

hello .my 2 cents worth just started on this forum.i have a 427 bbc bored .060 about 13.5 comp i do rev it pretty high i used to shift at 8500 but now at 8100 easier on the valve train.the engine has steel valves manley severe duty 2.25 and 1.94 cut down to 1.92 .the car weight is 3550 with me in it and it has run a 10.12 in the 1/4 with a 1.39 60 foot with the front tires in the air and spinning i still have the video.this engine has gone to 9200 but it will drop a valve when you do it.if you do want to rev a big block up use carillo rods keep the rods at .002 and the mains no more than .0025. and most important use the comp cams belt drive with the idler wheel i have went over 200 runs at 8100 rpm and have not broke anything .also make sure you buy very good valve springs will need close to 300 psi seated my cam is comp 286 dur @>050 dart intake switching to victor 454r for the labour day weekend and a 1190 demon car is a 70 camaro baldwin motion clone 4.56 gears turbo 400 the 10.12 was with 11.5 by 29 hoosier now have 13.5 by 30 m/t et street they barely fit caltrac system i live 4 1/2 hours from the nearest drag track so it is taking me a while to get it dialed in.having fun amyway.hping for 9s soon maybe labour day myabe not.i do have a 400 hp nos kit if i dont get the nines i will have to put it on.lol

Welcome aboard Mike,

Glad you brought my old post back from the dead!

I dearly loved my old junk301 engine, but also the torque of my 406 that is now on my engine stand b/c my new 496 is in my car now.

pdq67

Paul,
I am piecing together a BBC right now that will have a 4.5" bore and a 3.76" stroke.
I like my 427's so much, I decided to build a large bore short stroke motor. I know the trend is BIG motors these days, but I am partial to the 283's and 301's of the old days. Even now, I am much more interested in a 396 or 427 big block rather than the 500+ inch engines.
By the way, I just got home from a 7500rpm, gear grabbin, rubber burnin, ride in my 13:1 compression 427 camaro (burning E85)........talk about happy! :)
Smitty

Glad to see this thread brought back to life. I'm doing my version of a big bore - short stroke engine. CNC Bowtie block at 4.600, Lunati Pro Mod 3.75" stroke crank (499 cubes) , Lunati Pro Mod rods, Isky Red Zone solid rollers with street option, Pro Topline 320cc runner heads, SRP forged pistons with 11.25:1 compression. The cam will have the same .050 duration numbers as the old L-88 (264/270) but .725 lift and I'll run Jesel shaft rockers. Induction is up in the air at this point but I'm looking at one of the redesigned Weiand single plane 4150's and a 1050hp Holley. I'm a month or so from building this monster and it'll eventually find a home between the frame rails of my '82 Corvette with a beefed up rearend and a Super T-10 with nodular case and midplate.
It'll be my street toy that will make an occasional trip to the strip, more for bragging rights than anything else. I'm sure that traction below 30mph will be a joke. What I'm looking forward to is downshifting to third and mashing the loud pedal at 70mph.
Can I get a he!! yeah :D :D :D :D

Gary,
That post brought a smile to my face!
Smitty

I told the machinist that's doing the work on mine that when I do the downshift and floor it, I want whoever's in the passenger seat to mess their pants every time...and the driver sometimes as well! I'll keep everyone posted, it'll definitely be broken in and tuned on a dyno. I'm hoping for 725 - 750hp at around 7800.