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is short stroke/high rpm worth it?

O

olov

doing something stupid
Joined
Aug 11, 2003
Location
warrenton, nc 27589
hey, i'm fixing to start hunting for a block and start a turbo engine build up. at first i was thinking of getting a block bored out and creating the max displacement, run somewhat high compression, and run somewhat high boost. not sure of these numbers, but i was thinking of a naturally aspirated compression and over 10 psi if i o-ringed the block, good gaskets, etc.

then i watched getaway in stockholm 2, and i started googled for the specs of the escort cosworth. what i get from the pages i read, is that it's basically an engine with a bore larger than it's stroke "90,8 x 77,0 mm", 16v, and the race version has an oversized Garrett T3/T04B turbo(T35). running 2.5 bar(is that over 30 psi?)and yes, i know it's got alot of turbo lag, and the power band makes it horrible for normal driving, and i'd have to get the best valve springs $ can buy. but once the huge turbo kicks in, it'll fly. and some of those cars were rwd. if it's possible to get anywhere close to the escort cosworth, it would be worth it. "Ford Motorsport claim a 3s 0-100 Km/h in any conditions (including gravel)!"

so my first question, was would it be worth it; time/$ for the performance? and are there parts for this type of build up? EricF posted about destroking a B21 back in 2003. would this be the ideal block?

thanks guys for the patience with this post
 
you can bore and stroke and still be oversquare. lets say you ahve a B21 the bore it 200cc's(or get a good B230 or B23) then you stroke it 200cc's (I.E. penta marie crank) and then you still have the same ratio as a B21 because 200cc's sroked and 200cc's bored cancels each other out.

i haven't heard much about DEstrokeing but i know if you really want to try this i think there were some 1.9 liter OHC motors in eurpoe and some 2.0 liter DOHC 16V's. i don't know if they were DE stroked or bored i would assume DE stroked tho. i think boreing and strokeing would probly be better i love the torque my B21 has i can only imagen how much it would have with 400 extra cc's.
 
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The only GOOD reason to De-Stroke is to reduce displacement to fit within a set of rules. Sayyyyy you have a 2.3 liter engine and rules require 2.0 liters max. Otherwise displacement is always your friend for making more torque and thus, power.
The common gig is to increase displacement and therefore torque for a given engine speed.

Some like to say that "Revs are free" but "Free" is not how I would describe what it takes to make a peaky engine that will have a very narrow powerband and be hard to drive for the 90+% of the time we are driving. As sporty as we all like to think that we are we are rarely driving our cars as though we are escaping Deputy Doughnut who is set upon giving you a good thrashing. Have you ever driven an engine that does not wake up before 6000? By this I am NOT referring to VTEC Hondas. They are a different animal altogether. That motor that winds up to sayyyyyyy 8500 will have good power from say.....6800 to 8400 and make no torque or even want to keep running under that. Oh....Miss a shift and it may do a Kaboom!! trick. To make use of it you will HAVE to have a close ratio gearbox and a final drive ratio that will keep that thing spun up to ohhhhh 6000 at 75mph.

I have done this stuff..........The high RPM gig is great in the racecar for some, but in MY racecar I have one that makes MOUNTAINS of torque from 3000-7000. It runs smooth with perfect drivability, and I will leave 'sporty' in the weeds whilst he is trying to get the high strung thing 'on the pipe' in a race of almost any kind.

Build a strong one that will hold together and turn up the boost with good components.
You will love it.
John Lane.
 
i know all about torque, i have a 94 lt1 camaro 6 spd, i can start up in 4th or 5th gear if i wanted to(it would be slow though), i can usually lose anything right off the line b/c of the low torque band, and it was geared for the max gas milage, not acceleration. stock it runs 13-14's in the 1/4. and right now my daily driver is a formerly abused(by last few owners) 88 240 with over 300k, if i can drive that, i think i can deal with a fresh short stroke motor at the bottom end of the pwr band. and do you really think i'd have to change the gearing that much? top gear at 75mph at 6k rpm's? i'm thinking more like my camaro, the top gear is so tall i run 90 mph at just over 2k rpm's. i'm thinking gear the first few gears to utilize the high rpm pwr band, and then back it off with the last few. my car shouldn't have that much drag at that speed.

anyone elses thoughts?
this guy in sweeden posted his engine and wrote, "B17 crank, B23 block, steel rods, forged pistons, 16 valve head and a huge turbo makes a very interesting 2 liter motorcycle revving engine" so it's got to work, haha.
 
So try it and report back!!

I have driven the high revving things and prefer lots of torque.......not exactly stump-pulling torque as your camaro makes, but from 3000 on.........This is my preference.

For something that winds up to a telephone number you will need gearing to make use of the high revving nature of it. Asking something to try and pull 2000 rpm's at 90 that won't run intil 5000 clearly won't work very well. This is why I like a WIDE powerband. We tend to make larger powerbands with motors that make their power before say.......7000.

Whatever you do.........Have fun with it.

JL.
 
"HP makes your car fast. Torque just breaks things." I like the idea of high revs for that alone.

My theory: If you could have 250 ft lbs and 350hp, you'd have a fast brick that wouldn't break M46s.
 
isaac said:
"HP makes your car fast. Torque just breaks things." I like the idea of high revs for that alone.

My theory: If you could have 250 ft lbs and 350hp, you'd have a fast brick that wouldn't break M46s.
Click to expand...

*Bzzzzzzzzzz..........Wrong.
A stock M-46 will break with a steady diet of 200lb/ft. Ask it to go faster and it will break at a higher speed.

The flip side of this is that you will be having more fun when your M-46 gives it up.

I have broken plenty of M-46's with 130 horses. Really. It takes surprisingly little effort.
I am shocked that all of you with your big power engines haven't been collecting broken M-46 parts in quantity. I still have some of my broken Quaife gears just cuz they are cool.
Heehee............

JL.
 
My Naughty toy sports a 93mm bore and a 73mm stroke. It would be a candidate for four valve heads and making it wind up to a telephone number but it goes sooooooo silly fast now I can hardly see the point. I am going to change from a 3.5 rear axle ratio to a 3.0 ratio to up my top speed. I currently run a 1 to 1 top gear and am thus gearing limited to 130 or so. Gets there in a hurry on gravel.
JL.
 
the poi said:
And anyway, our motors ARE oversquare: 96mm bore and an 89mm stroke
Click to expand...

Penta B230 2.5L crank is 86mm stroke. Stock 2.3L B230 is 80mm. Dave Barton's 2.6L is 97mm x 89mm.
 
Don't worry about the short stroke idea, it's a trick for making engines with 4" strokes stop ripping rods apart.
Any engine with 3" stroke or less has no worries on the street or most tracks.
I have said it before, there are plenty of 3.5" stroke engines with 4" bore at dirt tracks across the country turning 8 grand.
Disclaimer: My opinions are presented entirely for your amusement.
 
JohnLane said:
*Bzzzzzzzzzz..........Wrong.
A stock M-46 will break with a steady diet of 200lb/ft. Ask it to go faster and it will break at a higher speed.

The flip side of this is that you will be having more fun when your M-46 gives it up.

I have broken plenty of M-46's with 130 horses. Really. It takes surprisingly little effort.
I am shocked that all of you with your big power engines haven't been collecting broken M-46 parts in quantity. I still have some of my broken Quaife gears just cuz they are cool.
Heehee............

JL.
Click to expand...

no it won't. I beat the ever loving **** out of my m46 for two years and it dinna break. and a year and a half of that was at *least* 200ft/lbs at the wheels. (check out the dyno plots, i ran the same turbo and the same boost when i initially f+t'ed the car. trap speeds havent changed significantly ~ 2 mph or so). I suspect the breakage that most people experience in the ~ 250 + ft/lb region is more a function of operator abuse/error/overzealousness.. in my case I liked to run the 10w40, reasonably fast shifts (occasionally forcing when it wouldn't go, but this wasnt the norm), dispatched 2.5 diffs with that transmission (man those spider gears were nasty looking.. oh wait, they didnt exist any more, just pieces of the past scattered around the housing hahaha).

now thats not to say i'm going to get on the soapbox and claim that the m46 is the badest mother ever, i think there are plenty of people that can proove otherwise, and I'm willing to believe that there are definite and low limits to what it can and cannot handle, but 200ft/lbs is a bit rediculous, considering stock turbo cars make ~190 out of the box. I would wager to say that anyone thats not running mid-low 14's with their manual and consistently breaks transmissions, is doing something wrong. My .02 (and any asshole that can snap two diffs in 6 months is probably abusing things as well... and I do. its fun :D )
 
my final thoughts

i guess the volvo can make an impressive amount of torque because of the replies i got(i guess it would have to be able to make over 300 hp, duhhh me). and since the engine is already "oversquare", and you can still bore them and be "oversquare", i was thinking on the tangent only. and since i am new to "the turbo life" i thought large amounts of power were not reachable except for extreme applications. i failed to remember that my buddy has, basically, a bored out b230__ with the normal bolt-ons running 12-15psi, and that had plenty of power, and was a daily driver. so i think i'll hunt for a good block (get it o-ringed), look into boring it out, maybe a stroker kit(if the price is right), and put my effort and money into a good tranny, suspension, fuel and brake system. i still would like to put top notch valve springs in, just in case i find a turbo that uses high revs. so thanks for saving me the time i would have spent trying to reduce my cubes/power and increase my headaches. back to plan A
 
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linuxman51 said:
no it won't. I beat the ever loving **** out of my m46 for two years and it dinna break. My .02 (and any asshole that can snap two diffs in 6 months is probably abusing things as well... and I do. its fun :D )
Click to expand...

Then you are not making enough power!! NAH-NAH!!!
My two cents are worth every bit ass (no type-o) much as yours!! NAH-NAH!!
Exactly what you have paid for 'em. NOTHING!! NAH-NAH!!

For the feller who was asking a question about bore vs stroke.......
As stated earlier......MORE DISPLACEMENT.........More air in and out........More boost......More power. A longer stroke can still be asked to spin faster then stock with good parts if you are wishing for more top end. You will still gain torque. Good this torque thing is.

You give it more poke and you will break drivetrain parts downstream. Expect it. Except for those of us with that ever so rare 'Magic' M-46 (who shall remain nameless to protect the guilty!!) we then look into how to install a stronger transmission (done in several flavors by folks on this page who have been unable to find their own 'Magic M-46') and then other stuff further downstream..........Axles.....Wheelstuds......Rear suspension upper arms......You get the idea. Worth it? I think so.
I also get a kick out of teasing these guys. Heehee.

All my love........John Lane.
 
there is no replacement for displacement.

horse power makes your car fast sometimes. torque makes your car fast all the time.
 
Boosted2003 said:
Displacement doesnt always make torque. Its how heavye the rotation mass of hte crankshaft is.
Click to expand...

No, that's incorrect. THe rotational mass of the crankshaft has nothing whatsoever to do with how much torue is produced. The downward force on the pistons multiplied bu the stroke of the crank is what determines torque (plus losses to friction).
 
i already forgot about this thread. i'm pissed that none of you seasoned vets mentioned squish, swirl, burn rate. oh well, i guess us newbies have to learn to search sometime or another.

well now, i'm thinking either a late b230, or maybe a b21 bored and put in oil squirters. when i learn more about how to make a good squish motor, i'll be back in the performance thread asking about cams/custom pistorn, block/head shaving, etc. but till then, it's just block hunting and band aid applier to my dd for me.
 
Squish........Swirl........burn rate.........All these factors help with that nice large displacement motor you are going to end up building. The better you do in the head the more you need a good strong bottom end.

Have fun!!

JL.
 
JohnLane said:
Then you are not making enough power!! NAH-NAH!!!
My two cents are worth every bit ass (no type-o) much as yours!! NAH-NAH!!
Exactly what you have paid for 'em. NOTHING!! NAH-NAH!!

For the feller who was asking a question about bore vs stroke.......
As stated earlier......MORE DISPLACEMENT.........More air in and out........More boost......More power. A longer stroke can still be asked to spin faster then stock with good parts if you are wishing for more top end. You will still gain torque. Good this torque thing is.

You give it more poke and you will break drivetrain parts downstream. Expect it. Except for those of us with that ever so rare 'Magic' M-46 (who shall remain nameless to protect the guilty!!) we then look into how to install a stronger transmission (done in several flavors by folks on this page who have been unable to find their own 'Magic M-46') and then other stuff further downstream..........Axles.....Wheelstuds......Rear suspension upper arms......You get the idea. Worth it? I think so.
I also get a kick out of teasing these guys. Heehee.

All my love........John Lane.
Click to expand...

Bull****, I paid for my .02, just ask dana ;)
I made enough power to dispatch a couple o diffs (Which seem to outlast autoboxes, its kind of a pick your poision in terms of what you'd rather have break these days).
and my m-46 is damn well magic. 200k iron case m-46, came off one of those veeee sixes you love so much in fact.

You do realize that you hafta hit the clutch when shifting right? NAH-NAH!! :)
 
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