this combo has been spinning through my head for some months now.

this is what i would like to try out.
a destroked ls1.

my thinking is this.

a low dollar destroked short block consisting of
a 6.0 iron block.
4.8 truck crank

these two parts would have a 4.030 bore and 3.26 stroke.

that comes out to 332 inches. high winding inches i would think.

of course to keep it low buck, i would use a dyers 6.300 inch 2.10 journal rod. some good hp bearing from polydyne already coated, a set of pistons with a 1.090 compression height would be needed. to keep the low buck theme, i would need a set of pistons from the "shelf"...

a common piston per say.

well, after some thorough searching, i have come across what i believe to be the perfect piston.
its cut for believe it or not a ford.
347 stroker piston. flat top forged. 1.090 compression height. 1/16 ring pack.

to complete the short block i would have the block decked .005 for a zero deck piston combo, run a .020 cometic gasket set and stud the bitch.

with proper crank work, this thing should spin freely to just this side of the moon.

what do ya think????

any one interested in putting together a theoretical cam grind for it? lets say solid roller.....

steve frank

 

btw...

i would spray the **** out of it...

steve frank

 

ive been wanting to build a de-stroker for a long time. is that F*rd piston a true flat top? what valve angle is a 5.0? Id say a solid roller (obviously) in the 265/260 xxx/xxx 112 range.

 

what would valve angle have anything to do with a true flat top.
the piston should work.
there would be things needing to get checked of course. like skirt to throw clearance ect. but it is a true flat top.
some are not. the one i have in mind is.

i would cut my own valve notches if need btw at the correct 15 degree angle.

steve frank

 

lest say this motor combo would go into a 2650 lb wet, 2830 lb race weight car. with a glide on probrake with a 4800-500 stall verter. enough tire to hold it of course with enough gear to get it through the lights at about 8200-8500 rpm in high.

feasable? ideas...

any other motor combo's sound interesting?

steve frank

 

i was just wondering what the valve angle of the ford heads were. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" /> OBVIOUSLY if its a flat top the angle means ****.

i figured you'd cut your own anyway.

i simmed the cam above with .700/.600 and a 113 IC and it peaked at like 7500 on DD2000. not THAT accurate..but fun to play with.

 

desk top dyno?
what did that program tell you exactly about the combo?

hp any other info?

i never did like that stuff myself but its fun to play with.

steve frank

 

Is there a class you want to race in that limits the displacement? That gives you weight breaks with a reduced displacement?

Otherwise I honestly can't think of a reason to do this!

When you get down to it the larger motor is going to have the potential to make more power than the smaller motor, period. If you want rpm just spin the larger motor up there also - you will make more power doing so.

As for the "rpm advantages" of a destroked motor - before you run into any rpm wall on the larger motor you are going to run into a wall using the cast crank (in both motors). Then you will need to address oiling issues (again, the same in both motor). Then there is probably valvetrain issues (solid roller is an easy answer, or an exotic hydrualic setup) - these two will be equal in both motors.

In reality you will either run into budget considerations (high rpm parts are $$$$) or given plenty of funds and a strong enough block you will basically run into a wall around 10,000 rpm where you are going to have no luck without going to an exotic valvetrain (coates, pnuematic, etc.) - and it's going to be very expensive and maintenence intensive to get that high.

Basically the destroked block will have no rpm advantage because other factors will constrain them both equally.

About the only argument I can come up with for a smaller motor is if you are class racing and have limits/get weight breaks, or if you are running a power adder great enough that you need more piston comp height to make a strong enough piston. I don't think either of those are really going to be that big an issue though.

Chris

 

yeah, at a given rpm a bigger motor will put down more power than a smaller one...all things being equal. but id do it just for fun.

the numbers they give you on desk top dyno are trash, but that combo peaked at 517/431. on DD2k a stock car with a B1 makes 380/416 so is SEMI accurate, but again...its more for fun than anything else. a learning experience persay?

<small>[ July 14, 2002, 09:23 PM: Message edited by: Ryan ]</small>

 

I went a little wild with this one and it looks a little fun to try to handle this little beast

Using 278/292 soild roller(don't know if one exists but hey this is bench racing <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" /> ) 14:1cr and heads that flow plenty with 2.1int 1.625exh

Peak Hp 765 @ 9500 Avg Hp (6000 to 9500) 684
peak tq 501 @ 7500 <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> avg 465

Through that into a fully prepped 2830 chassis

I used a th400(me no likes the glide) with a 7500 stall 8"verter with 5.13 gears= 8.14 @ 158 <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" />

LAter <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

this is a discussion for doing some thing differant. i am seriously considering doing this combo just for the **** of it.

i also cant see a 422 spinning up to 850 myself.

how about knocking the crank down to about 3.16 or so, run a 6.400 2.0 crank journal rod to get the shorter stroke.

i cant seem to find my for rod ratio's..

anyone figure out what the first combo would be? i would guess some where in the 1.7's....

i would also guess real world numbers of 475 rwhp and close to that in torque...

steve frank

 

My sim says the rod ratio to be 1.933 for the first setup and 2.025 for the second

LAter <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

I am not saying do the same thing as everyone - I am all for trying new things. At the same time though I equate fun with going fast, so in that aspect I don't think this is the best choice <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I don't see any reason why a 422 couldn't turn 8500 - oiling issues will not be tremendously different than with your setup, block strength may be an issue, the heads are there, and a custom intake will be required with either setup.

But the point is to make the same or even more power the 422 doesn't need to turn nearly that high.

For the cost and level of work/parts going in why not do a turbo or blower setup. Be one of the first people to throw a speed-pro w/ wideband in on a piggyback setup and I bet you would have a killer setup.

If you like the lower displacement just to say you have a smaller motor or for nostalgic reasons, by all means. But for turning high rpm, making power, going fast, etc. I just don't think it's the ticket.

Chris

 

4.8 crank is 3.268" right? Pair that up with a 4.10 bore block and you'd be around 345-346 ci. Stock ci <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> Bore:Stroke still isn't as good as the DZ302 though. I like the "stock ci" idea, although you'd have to go with a resleeved alum block.

J.

 

On a little engine like that, making torque is going to be tough if you want to spin it to the moon. I have a lot of experience with 310 ci SB2 engines, with a stroke of ~2.9-3.1, and a bore of 4.020-4.040, and which ever makes 311 ci. its a class rules thing for us.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ChrisB:
<strong>I am not saying do the same thing as everyone - I am all for trying new things. At the same time though I equate fun with going fast, so in that aspect I don't think this is the best choice <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I don't see any reason why a 422 couldn't turn 8500 - oiling issues will not be tremendously different than with your setup, block strength may be an issue, the heads are there, and a custom intake will be required with either setup.

But the point is to make the same or even more power the 422 doesn't need to turn nearly that high.

For the cost and level of work/parts going in why not do a turbo or blower setup. Be one of the first people to throw a speed-pro w/ wideband in on a piggyback setup and I bet you would have a killer setup.

If you like the lower displacement just to say you have a smaller motor or for nostalgic reasons, by all means. But for turning high rpm, making power, going fast, etc. I just don't think it's the ticket.

Chris</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Chris,

the reason you don't spin a 4.075" crank in the 422 to 8500 is not oiling it's piston speed. The piston will be moving 5700 ft/min.

A engine should limit PSN SP to a range of 3750-5000 ft/min. (Race engines on the 'leading edge' of technology are running up to 6000 ft/min.) To run over 2750 ft/min requires 'better than production'parts. To run at 3750 ft/min or higher, you will need 'state of the art' reciprocating components (connecting rods & bolts, pistons, etc.)like those present in Drag Racing's Pro Stock class or Formula 1. These components must be both extremely light and strong.

This is the fastest way to break a rod. Period!

"In reality you will either run into budget considerations (high rpm parts are $$$$) or given plenty of funds and a strong enough block you will basically run into a wall around 10,000 rpm where you are going to have no luck without going to an exotic valvetrain (coates, pnuematic, etc.) - and it's going to be very expensive and maintenence intensive to get that high."

Needless to say that @ 10,000 rpm engine usually needs very expensive parts everywhere. 10,000rpm is where ProStock boys are spining 500 cube engines today and they don't live very long. If we are talking about engines the size of small blocks in an endurance engine we have about a 700 mile engine that spins 9300rpm. If you want a street engine going that fast and making it live would require a stroke below 2.75" If you want to spend alot of money on a high reving street engine it's almost a necesity to keep it below 7500rpm. With a 350 that's not really even needed.

Bret


As for the high rpm engine. If you are going to do it don't waste time with the 6.0L engine. Why would one build a small displacement engine and make it heavier. Re-sleave a LS1 engine so you can run 4.125 then throw that 4.8L crank in it and you'll get a 347 that you can spin up into the 7,000 and it will live. If you are going to do a small stroke make it have a large bore.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>the reason you don't spin a 4.075" crank in the 422 to 8500 is not oiling it's piston speed. The piston will be moving 5700 ft/min. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"></strong>

On the LS1 engines I would be very concerned about the oil system at that rpm and I think that is something that needs to be considered.

But good point on piston velocity. that said you can do it if you are willing to spend the money on the parts. If you look at most of the 422 buildups out there they are already using forged or billet cranks, billet connecting rods, etc. Most are custom piston jobs so to spec one for that type of rpm wouldn't be that big a stretch.

Now is the thing going to be daily driver reliable? Probably not, but then I don't think a 327 turning 8500 is going to be either. And if we specify a power level, say xxx hp, the 422 making that or more power at say 7000 rpm is going to be much more reliable than the 327 at 8500. You can make more power at the same rpm (since I would submit at 8500 you would still be spending the money on a billet crank, rods, etc.) or the same power at a lower rpm.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
A engine should limit PSN SP to a range of 3750-5000 ft/min. (Race engines on the 'leading edge' of technology are running up to 6000 ft/min.) To run over 2750 ft/min requires 'better than production'parts. To run at 3750 ft/min or higher, you will need 'state of the art' reciprocating components (connecting rods & bolts, pistons, etc.)like those present in Drag Racing's Pro Stock class or Formula 1. These components must be both extremely light and strong.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

Agreed, though I think the numbers are a bit conservative - but that's a personal call. But again, consider that most large buildups are running billet crank, rods, and custom pistons - and they already are at the part level you would need for those rpms.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">
If you want a street engine going that fast and making it live would require a stroke below 2.75" If you want to spend alot of money on a high reving street engine it's almost a necesity to keep it below 7500rpm. With a 350 that's not really even needed.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

But in reality how much of a street car is a 8500 rpm small displacement engine going to be? Yes it should be more reliable at 8500 rpm than a 408, 422, whatever, but I would submit that none of them are going to have daily driver reliability - so I don't know how much of an issue that is. And again, you know the larger motor at lower rpm will make the same or more power, be more reliable, and be faster at the track (better area under the curve).

I guess what it boils down to is I think 8000-8500 is doable on a 422 with top notch parts, but that's about the limit (reasonably).

In just about any racing class - excepting weight breaks and displacement limits - motors become as big as feasably possible. Those 700in mountain motors don't proportionally make that much power over the smaller 550-600" cousins - but they do make more. Which is why that is what most people end up with in that class.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"><strong>
Re-sleave a LS1 engine so you can run 4.125 then throw that 4.8L crank in it and you'll get a 347 that you can spin up into the 7,000 and it will live. If you are going to do a small stroke make it have a large bore.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">There are plenty of stock bore/stroke motors spinning that high and living (though 7000 is about it). If you throw in an aftermarket setup 7000 should be no problem. So why not keep the stock stroke with the bigger bore and turn the 388 to 7000?

I think it's an interesting idea, again, I just don't see the application. You have to be turning at least 8000-8500 for the larger motor not to be feasable at all. And then why destroke it - why not at least stick with the stock stroke? Giving up cubic inches is giving up power - and in the end a small inch high rpm motor is going to be a dog on the street. Unless you feed it with a blower <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Chris

 

I agree with Chris B I think it is a waste of time and money IMO.

Stick with more cubes and lower rpm. Cheaper, more reliable and more power given the oiling constrants and crankshaft restraints you are working under.
Cheers,
Chris

 

If you are on a budget, an LS1 is not the motor to play around with <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Besides, doesnt the stock PCM only have fuel and timing tables up to 8000?

 

guess ill just have to go and do it to see what it will do. ill let you know when its done.
who cares about street car stuff. im not talking street car.
i also like the 4.100bore and short stroke idea too.
the budget idea is there still. i think it can be done at a mear fraction of the cost. since the market is cornered on the lunati cranks.

swept volume is low of course and so will the torque, but i can see a small motor pulling 2.0-2.5 hp per cube easy.

try that with a big stroke motor. aint happened yet i dont think.
sure, the overall numbers wont be that high ill agree.

remember, this isnt for the following type of crowd. i am looking to try to break new ground here, on a budget of course (never said what the budget is either), just to see what can be done. if it works, thats kewl, if not... you get the picture.

i dont think it will need that much cam either. solid roller yes, but in the 240 duration range max. remember, this isnt a old school motor so the old school approach wont work in my opinion.

oiling issues are a concern. i have the cure for that too. and it will still put me in cheaper than a new crank from lunati.

i am still listening to folks opinions on tis tho. keep em coming.

steve frank