Guest JAMIE T Posted October 4, 2002 Share Posted October 4, 2002 Lockjaw, I agree with you on the long rod theory, longer rods keep the piston at TDC longer than short rods. The article you mention is on AFR's website. They did the build-up on that 350. It's titled "The 350 Chevy Should Have built". The engine made over 450hp, on 87 octane, and 11.1 compression. Quote Link to comment Share on other sites More sharing options...
zcarnut Posted October 5, 2002 Share Posted October 5, 2002 Anyone wanting to build either a stroker or a "de-stroker", then email me as I have both a LD28 crank and an L20A crank for sale. I have to have $250 for the LD28 crank as it has been polished, magnafluxed and checked for staightness. $150 will get the L20A crank. Quote Link to comment Share on other sites More sharing options...
Guest 280Tom'z Posted October 5, 2002 Share Posted October 5, 2002 i'll buy it if i have enuff $$$ after i go pick up this 76' monday beacause i want to make a stroker, and correct me if im wrong but i need the 240 rods and flattops to make the 3.1 Quote Link to comment Share on other sites More sharing options...
Guest gprix1 Posted October 5, 2002 Share Posted October 5, 2002 Is de-stroking when the I.R.S. gives you all your money back with a letter of apology? Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted October 5, 2002 Share Posted October 5, 2002 Originally posted by RickS:Is de-stroking when the I.R.S. gives you all your money back with a letter of apology? I think that is when "hell freezes over" That was exactly the article I was referring to, and I remember the thing had some insane compression and ran 87 octane, and liked it. I think it even had small valves too. I may explore the long rod theory a little more and see what it does. I have a friend who did that with his poncho ( another friend), and he is running some crower rods for a big block chevy, and they are longer, and his engine is strong. He has ported edelbrock heads, a roller cam (mild), and some sort of extrude honed exhaust manifolds, and his car runs sweet. He put a 6 speed richmond in it. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 26, 2003 Share Posted May 26, 2003 De-stroking is for boosted motors, for the most part. The idea is to put more direct pressure on the crank. The down side is that the rod has less leverage on the crank, which may limit torque. The up side is that the motor can rev higher, and produce more power. The variables might be that good combustion, like in a highly boosted turbo motor, or a high compression N/A motor, would make up for the lack of leverage the rod has on the crank. Also, a greater rod angle would put more stress on the piston and cylinder wall, and parts would ware out quicker. Every application has it's perect bore, stroke, displacement, rod ratio, comp. ratio, yada yada yada... The truth is that for every choice you make when you build your motor, you also make a comprimise... But this is the performance board; I'm sure everyone knows that. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 26, 2003 Share Posted May 26, 2003 By the way, I think the perfect stroke for the L28 is 83.6, if you could find one that size Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 26, 2003 Share Posted May 26, 2003 I've seen high deck kits for sr20's... Why couldn't this be done with the L6? Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted May 26, 2003 Share Posted May 26, 2003 De-stroking is for boosted motors' date=' for the most part. The idea is to put more direct pressure on the crank. The down side is that the rod has less leverage on the crank, which may limit torque. The up side is that the motor can rev higher, and produce more power.quote'] More direct pressure on the crank? I have no idea what you're talking about there. If you reduce stroke, you WILL (as opposed to may) reduce torque. Please go to the beginning and read this whole thread again. On any L6 combination I can put together, destroking ALWAYS loses power potential. Yes, the short-stroke motor can rev higher (assuming equivalent piston strength), but not by enough to make up for the lost torque. Believe it or not, to maximize the power of a motor you pretty much want to maximize its displacement, via bore and/or stroke. This applies to boosted and NA motors. Yes, you can make as much power with a 2.8 turbo as you can with a 3.1 turbo, but only if you have more boost. With equal boost, the larger displacement motor wins. At equal power levels, the bigger motor still wins, as it's operating at a lower boost level, so less lag, more streetable. Why do you think 83.6 is the "perfect" stroke for an L28? I would beg to differ:) Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 26, 2003 Share Posted May 26, 2003 Maybe I didn't phrase it to well, so let me explain... At a certain point during the stroke, the rod reaches its greatest angle, relative to the track the piston follows. stroking the motor will shorten the the rod ratio (the lenngth of the rod relative to the stroke) and the rod will reach a greater angle (relative to the track of the piston) and the force excerted is split between pressure on the crank (making it go round and round) and pressing the piston against the cylinder wall, and power is lost that way. My idea was to put a spacer between the block and head (the thickness being equal to the length of one chain link, so's not to disrupt cam timing). The piston could go a certain distance up into the spacer (depending on ringland height) and you could use a stroker crank and still maintain a nice long rod ratio... I'm not dogging on the stroker at all, or hyping the de-stroker... I'm just pointing out the differences (what makes the difference such a big deal)... And dude, I was joking about the 83.6mm stroke; chill out! Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted May 26, 2003 Share Posted May 26, 2003 Forget the spacer - just use the taller LD28 block. There are people using it on this board which are quite happy with it. Why re-invent the wheel? Cheers - Doug Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 26, 2003 Share Posted May 26, 2003 Sorry, didn't know there was a block with a taller deck height... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 26, 2003 Share Posted May 26, 2003 Might as well build a stroker then, with the LD block and nice long rods... Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted May 27, 2003 Share Posted May 27, 2003 I think you're backward on the rod angle/leverage issue. Since max cylinder pressure is ~15 degrees, the longer the rod, the worse the rod angle in terms of leverage. A shorter rod will be situated at a greater angle with the crank throw, which will give greater torque. This is augmented by the fact that since the rod is in pure compression, and is at an angle, and has to react all the vertical force from the piston, the actual compressive force in the rod is actually higher than the downward force on the piston. The downside is piston side load. The shorter the rod, the greater the side load, which means greater frictional losses. Anyway, my point is that longer rods aren't necessarily better for performance. Too long and you should lose torque due to the rod primarily pushing on the crank radially, with the tangential torque-producing force minimized. Too short and the side loads will take away from the gains from improved angularity between the rod and crank at max cylinder pressure. In any case, increasing displacement is most likely a power-improving proposition, even if frictional losses are increased due to increased rod angularity. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 27, 2003 Share Posted May 27, 2003 That is true, and strokers do produce more low/midrange torque, but there are more factors to consider. For instance, greater rod angles mean higher piston speeds at equal RPM's. At a certain point, the expantion of the gases after igniton is less potent, if you will, in respect to the speed of the piston; the piston is almost keeping up with the combustion... Well, not really "ALMOST", but a longer rod will allow the expantion of the gases to excert a greater force on the piston at higher RMP ranges, and promotes more top end HP. Think of it in terms of traveling at 30MPH and rear ending a car doing 10MPH, as opposed to rear ending a car doing 20MPH. I'm not disagreeing with you though, as even with a P-series head, I don't think the L-motor has the kind of combustion characteristics that would promote that kind of top end power; not like the crossflow head designs of todays engines. The stroker probably a more capible setup... But, like I said before, it's all about what the motor is intended for, and there's really no wrong way to go. Quote Link to comment Share on other sites More sharing options...
Guest POKINATCHA Posted May 27, 2003 Share Posted May 27, 2003 Look at Honda's two older Type R's, the Integra and the Civic. The 1.6 in the Civic was basically a destroked B18C5 out of the Integra with a slightly more agressive cam. The Integra had a r/s of 1.58, while the Civic's was like 1.9. The 'Teg made 109 hp/liter and the Cvic made 115.62, not a real big difference, especially considering the cam changes. Those engines ran out past 8000, too. The L28 has a better ratio than the Integra, and I don't anybody that goes out past 8000 on a street L28. I just don't see why you'd destroke if you didn't HAVE to for some reason. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted May 28, 2003 Share Posted May 28, 2003 I know this is pointless, but I believe the B18 is a stroked out B16, and not the other way around--but I could be wrong... Another point I do want to make is that slower piston speeds are produce better volumetric efficiency--it allows more fuel/air to enter the combustion chamber before the valve closes. this, again, promotes better combustion. One more point before someone replies to this; despite what it might sound like I'm saying, I have NOTHING against strokers, and I'm not trying to hype up a de-stroked motor... All I'm saying is that longer rod ratios are usually always more efficient... but, again, it depends on the motors purpose. Quote Link to comment Share on other sites More sharing options...
Guest POKINATCHA Posted May 28, 2003 Share Posted May 28, 2003 Well, just to show that I'm a Honda geek: the B18's actually have a significantly taller deck than the B16's, and are a newer engine. Plus, the Civic Type R is the only B16 to use the taller deck block. Anyway, that article about the "350 Chevy should have built" was pretty crazy. I would never have thought that you could run 11:1 in a small block on anything under 93 octane, but 87? Thats nuts. I bet if you ran 91 or better you could probably even squeeze out another half point of compression, especially with a little bigger cam. That almost sounds too good to pass up. Quote Link to comment Share on other sites More sharing options...
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