Heavy Z Posted October 15, 2003 Author Share Posted October 15, 2003 Point well taken, thanks John & Speed for the expository info on the subject. I know you guys don't like the 'all things equal' idea as it's usually hypothetical, that I can understand for sure. Anyone specifically building around a car will make different choices in how things are done. In my case, both engines already have the same cam, so my plan is to strip the 327 of everything it's got and just change the blocks. Cheap and relatively easy. I posted because I didn't want people to get the wrong idea about short-stroke motors based on terminology, as I currently have a nice one and know how it feels. It revs very quickly now and doesn't mind going big, but I'm also pretty sure that under these conditions with the 383 my Z will be an even 'faster-revver.' Quote Link to comment Share on other sites More sharing options...
DavyZ Posted October 15, 2003 Share Posted October 15, 2003 All that said, I'm making sure the motor I use is 350 ci or bigger For the LT1 swap I won't be using a stroker crank--the turbo should make the iron move just fine. Davy Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 15, 2003 Share Posted October 15, 2003 Speed (Dick) has it right, IMO. If you're on the street, then you probably don't want to be leaving lights dumping the clutch at high rpm, or cruising at high rpm. Unless you grew up on sport bikes. But even still, you'll draw alot of attention driving like that, and probably the wrong kind. If on the track, yeah, it doesn't matter. Except if you don't have your gearing right .... Johnc had a great point about other factors, as well as things not being equal. And on that matter, consider the manual transmissions and ratios available for doing the SBC swap (since that's the object of this comparison). Probably T-56 or Tremec TR-3550/TKO if you are going over drive. They have wide gear spreads, and low first gears. And what rear gears are you really going to put in? 3.545:1 or 3.7:1 most likely, since that's what's available mostly. Sure 4.11:1 is available, and so is 3.90:1, but not very easily found. I can tell you that my lumpy cammed 327 climbing the hill after turn 3 at the NHIS road course last week could have used some more TORQUE below 4500 rpm in 3rd gear. It kicked in there. Sure, I could have revved it further in 2nd, but I didn't want to rev it to the moon, and it didn't run well above 6000rpm anyway (a Holley Projection problem). But I wouldn't want to hear it do that much anyway. I did have to drive it 450 miles home . Under load, with the SAME driveline parts, the 383 will tweak the 327's nose. Climbing that hill after turn 3, I had visions of my 406 on the engine stand. Sure, I could pull away from even some modded 300ZXTTs, but I wanted to feel like I was ROCKETING up that hill. The 406 would have helped that. And how often do we really get the optimal parts setup (engine,trans,rear gears, etc.) anyway? Quote Link to comment Share on other sites More sharing options...
Guest Z-rific Posted October 15, 2003 Share Posted October 15, 2003 Okay... First, I think the BEST we can do here is compare the two at the flywheel. If we try to factor in transmission gears, rear end gears, tire sizes, etc., we will end up with pages full of numbers and headaches the size of Texas. I think, to say the extra torque of a 383 will cause it to rev faster than a 327 is a very shaky argument. Here's why. The 383 has a stroke of 3.75 inches, the 327 is 3.25". That's 1/2" down and 1/2 inch up, for a grand total of 1 inch more travel. Total travel for a 383 is 7.5" to 6.5" for the 327. How much extra torque is needed to cover that extra inch in the same time or even faster, as you propose? Now factor in the added rotational mass of a 383. Throw in the fact that the 383 is compressing more air/fuel mixture, thus increasing the resistance of the compression stroke. I'm no engineer or physicist. In fact, of all the people responding on this post, I may know less about engine dynamics that anyone. But it seems to me that the 383 would have to be putting out at least 15% more torque to rev as fast as a 327. That's 350 lbs vs. 402 lbs. And I'm guessing 15% is at least a few percent short. And, as the engine revs faster, wouldn't the rotating mass be more and more harmful to revs? Meaning a 383 might be better compared to the 327 at 3000 rpms, but not at 6000. Okay, I'm prepared for a hammering. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 16, 2003 Share Posted October 16, 2003 I won't hammer you. I think you left out the load - that is what holds both back equally. You have more air/fuel per stroke on the larger engine. The bigger engine may not rev as high, but it will get to it's redline faster than the smaller motor will read the same rpm. HP is torque multiplied by rpm. Stroker has more torque. It will accelerate faster. Obviously if you want to take advantage of the smaller engine and higher redline, gear it lower. Then you've reduced the load, and the smaller engine may accelerate the same or even more than the larger. Quote Link to comment Share on other sites More sharing options...
cyrus Posted October 22, 2003 Share Posted October 22, 2003 To sum things up The shorter the stroke the higher the speeds are possible due to crankshaft reliability. Bigger engines make more power and torque hence accel better. The bigger the engine the lower the RPM limit when all other factors are equal. Anyone ride a sport bike 15000 rpm or model airplane engine 25000 rpm. please read the above statements carefully. Quote Link to comment Share on other sites More sharing options...
deMideon Posted October 22, 2003 Share Posted October 22, 2003 So that means my 377 will beat the 383 right? Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 22, 2003 Share Posted October 22, 2003 "So that means my 377 will beat the 383 right?" the results will depend on the cars gearing and how well the cam/compression ratio/exhaust tuning match, the 383 with its larger displacement and slightly lower rpm range should pull better in the first 2/3s of the track if all parts are properly matched, the 377 with its greater breathing potential and slightly higher rpm range should tend to start pulling ahead after the cars in the higher gears , which is truely faster at the 1/4 mile mark should depend on which combo is taking the best advantage of the combo used! both should if correctly set up provide excessive hp/tq in the 500/hp500/tq range with the best parts and a huge grin! but if I had a 400 block ID BUILD A 406-421 displacement combo and get BOTH THE LONGER STROKE,LARGER DISPLACEMENT AND BETTER BREATHING FOR THE BEST OF BOTH POTENTIAL RESULTS Quote Link to comment Share on other sites More sharing options...
Guest Z-rific Posted October 23, 2003 Share Posted October 23, 2003 The original arguement, though, was that a 383 should rev faster due to it's higher torque moving the piston faster. I still think that may not be the case at all, as a) the piston travels 1" extra total (feel free to calculate the time needed to do so at a given rpm) the extra inch adds more friction c) more air/fuel to compress adds resistance to compression stroke. If we assume that more torque = faster revving, then a 427, with tons of torque, would rev faster than a 283 or 327. By the way, why aren't we all using Olds 350's as opposed to Chevy 350's, as the stroke is 1/10th inch shorter, the torque remains the same? And the rod length/stroke ratio is supposedly ideal for the Olds, as well as th ability to bolt on big block heads directly to the small block Olds. And the engine is 15# lighter! Quote Link to comment Share on other sites More sharing options...
Heavy Z Posted October 23, 2003 Author Share Posted October 23, 2003 the piston travels 1" extra total (feel free to calculate the time needed to do so at a given rpm) In both engines it's one revolution of the crankshaft either way you go. Both have to go through the push-pull motion, one is just janking and throwing pistons more than the other. Sure the 383 pistons take more abuse, but in doing so more torque is created. More torque pushing on the gears makes for faster acceleration, redline will be reached quicker, you'll have to shift faster, and thus is "fast-revving." Gearing can change this, unfortunately with my Z I have no room. My 5th is .73 and would turn too many rpms on the highway to gear down and cam up(also a streetability issue). Call me crazy, but his route seems less practical. I used to think otherwise but Grumpyvette's logic has me convinced that when considering a light vehicle 'quick-revving' has more to do with displacement than stroke. Good question about the olds engine, maybe someone will have an answer. Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted October 24, 2003 Share Posted October 24, 2003 .., By the way, why aren't we all using Olds 350's as opposed to Chevy 350's, as the stroke is 1/10th inch shorter, the torque remains the same.., And the engine is 15# lighter! An Ex-Olds guy speaking here (gotta lerve them ole 442's with their W25 Hood dual snorkel Hood Scoops). 1) We are not using Olds 350's simply because a kit doesnt exists for them. I'm not too sure about eh Olds 350 being lighter than a SBC...was your spec (15#'s lighter) taken from a fully dressed Olds? 2) The Olds bottom end crank mains are 3" to the SBC's standard 2.45": with the 400 SBC as the exception coming in at 2.650". This makes for a rock solid bottom end on the Olds-providing you are not expecting to go far beyond 4000rpm's. This extra bearing surface requires a more efficient oiling system-lots of blue printing involved to make an Olds survive at high rpm's. 3) Aftermarker Cyl.Heads for an Olds engine are too expensive compared to the more popular SBC's. Stock Old's cylinder heads have ports which are too small and this yields a redline that comes into play way soon than the SBC's. 4) A larger crank main, and intake ports being too small-are not reason enough to not use the Olds engines as much as the cost involved to overcome those two very serious problems. Joe Mondello, aka: Mr.Oldsmobile, even says the ultra ultra one area that can not be over looked on a true HiPo Olds engine is the Oiling System...then the Intake Ports to Cyl.Head Ports would come next. 5) The last reason is because there isnt a kit being offered-combine this with the previous cost prohibitive reasons-oiling & cyl.heads whose ports are too small...why would you? All those reasons are why I sold my Rallaye 350 a few years ago. After all the weekend's prepping the engine/trans (rest of the car were in decent order) I didnt like the performance. Heavy car-320hp was just not enough. The car sounded neat-with killer looks (1970) but the car was a led sled....for me-not a led sled by today's standards Now put that 320hp in a ligher car & performance would be quite different-still you can not dismiss the investment costs that brought about the meager 320hp Olds engine as opposed to the costs involved in reaching a 320hp SBC. The parts on an Olds that require tweaking to make them live at higher rpm's must be done by experts who understand the Olds engine....not by machinest who work on Fords & Chevy's all day long: which translates into extra dollars from the project's budget. Not so on the SBC. The parts needed to make a 320hp SBC are shelf bought items...no tweaking involved. Did I mention there is no kit for the Olds to go into a Z? Kevin, (Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
cyrus Posted October 24, 2003 Share Posted October 24, 2003 My goodness this post is driving me crazy. People are splitting hairs over things that are so insignificant it is amazing. What is important is the general principles, remember all other factors have to be equal: Short stroke can rev higher due to crankshaft reliability small bores can rev higher due to crankshaft reliability. smaller flywheel rev faster less inertia The larger displacement the more powerful an engine Turbos and Superchargers effectively increase displacement. The real important factor in not how who can rev in neutral the fastest, not who has the lowest gears that shift 5 times to go 30 mph. Don't tell me about a S2000 engine vs a big lazy v8. Remember this is with all things being equal. The only thing that matters is the cars performance in the quarter mile. For instance my LS1 240z reved up John Deer but runs 12.0 at 119 mph. So if I have any given engine doing the following makes it more power hence faster: More displacement more RPM more cylinder filling, turbo etc.. less recipricating weight less rotational weight Now if I do the reverse my engine will be weaker. Rember do not compare engine different engine... my 2 liter dohc engine with 12000 rpm redline running 21 psi of boost out powers you 1978 ford 460ci truck motor ohv....kind of crap. Just keep in mind the basics, if I make my engine have: More displacement more RPM more cylinder filling, turbo etc.. less recipricating weight less rotational weight it will be more powerful. Quote Link to comment Share on other sites More sharing options...
Guest Z-rific Posted October 24, 2003 Share Posted October 24, 2003 Cyrus, the original point made on this post wasn't about which engine is better suited or produces better results. Simply a discussion about which revs faster, be it meaningful or not. As Grumpy pointed out earlier, in the real world, gearing, tire size, weight, etc. have more an impact on revs than 327 vs 383. No question, I would drop in a built 383 before a built 327. More cubic inches yields more torque, whcih we are all after. Heavy Z, certainly a revolution is a revolution. But if it takes less distance for the piston to go up and down, the revolution would be faster. The big question is, does the more powerful combustion make up for the extra distance travelled and extra friction/resistance? I honestly don't know. And if it did, then wouldn't an engine with even longer stroke rev faster, due to it's stronger combustion? Kevin, I'm aware of the cost and oiling issues of the Olds 350. I have been to Mondello's site often. The Olds build up would probably cost double or more than the Chevy. I just like the idea of porting a set of big block, small combustion chambered heads on a small block. I know there are several cam choices, and very few intake manifold choices. Apparently, the Olds engines have tendancies to keep too much oil on top of the engine, starving the crank. Certainly fixable, but more $$$$. Mondello's valve train also improves high rpm problems, but more $$$. I have an Olds 350 and 455 laying around. Just don't have the cash to do anything fun with them. Limited funds are why there is a Chevy in my Z. But some of the guys here have $$$$, and it would be cool to see somebody do an Olds engine properly and drop it in a Z. Quote Link to comment Share on other sites More sharing options...
Guest plainswolf Posted October 25, 2003 Share Posted October 25, 2003 DAM this is interesting!!..... and HIGHLY educational. I have learned more about automotive/engine technology from reading discussions such as this than from any other source. PERIOD Because there is sometimes debate, the subject is more thoroughly analyzed and understood. Perhaps to many of you this is rather elementary or perhaps considered rather trivial, but to guys like me that is still so new to all of this I can't stress enough how even debates such as this, help me to understand more. Sort of my way of saying 'please feel free to carry on', and also thank you from a new guy. Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 25, 2003 Share Posted October 25, 2003 The original arguement' date=' though, was that a 383 should rev faster due to it's higher torque moving the piston faster. I still think that may not be the case at all, as a) the piston travels 1" extra total (feel free to calculate the time needed to do so at a given rpm) the extra inch adds more friction[/quote'] A 327 has a 3.25" stroke, the throw of the rod journal is 3.25"/2 or 1.625. The piston in a 327 moves 3.25" during 1/2 a revolution. With a zero deck height (to make things simple), the top of the piston starts flush with the top of the block, and moves down 3.25" below the deck surface at BDC (1/2 a revolution). A 383 uses a 3.75" (400 SB) stroke, the throw of the rod journal is 3.75"/2 or 1.875. The piston in a 383 (or 400) moves 3.75" during 1/2 a revolution. With a zero deck height (to make things simple), the top of the piston starts flush with the top of the block, and moves down 3.75" below the deck surface at BDC (1/2 a revolution). That's only a 1/2" of extra piston travel during a 1/2 revolution from TDC to BDC, not 1". Sure, that's more friction. But were talking about a 15% increase, not 30%. c) more air/fuel to compress adds resistance to compression stroke. I'm not following you. Why does this matter? Sure, it's a pumping loss increase. But you also get more torque from it due to the longer throw length. If we assume that more torque = faster revving, then a 427, with tons of torque, would rev faster than a 283 or 327. It just might, with the same load on each engine. In fact I am fairly sure it would (if they were all built to the same level of performance - not a mild 427 vs an all-out 283). Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted October 25, 2003 Share Posted October 25, 2003 This entire thread is just turning into a "if my engine makes more power it will go faster". DUH! The only "all things being equal" playing-field would have to include the same power outputs. Find a 327 that makes 300HP and a 383 that makes 300HP and see which revs faster... Quote Link to comment Share on other sites More sharing options...
Heavy Z Posted October 26, 2003 Author Share Posted October 26, 2003 Find a 327 that makes 300HP and a 383 that makes 300HP and see which revs faster... Ok, here's some DD2000 numbers to ponder, both engines have the same XE268H cam, RPM heads, carb, manifold, both at 399 horsepower: RPMs HP 327/383 TQ 327/383 2000 115/141 303/371 2500 153/186 321/390 3000 195/233 341/408 3500 243/285 365/427 4000 291/332 382/435 4500 336/372 392/434 5000 373/399 391/418 5500 391/398 373/380 6000 399/384 350/336 Quote Link to comment Share on other sites More sharing options...
SpeedRacer Posted October 26, 2003 Share Posted October 26, 2003 Heavy Z - That's not what you started out this thread to be about but........ what happens if the 383 can't rev any higher that 6,000 RPM but the 327 can go to 7,800 RPM? Horsepower is just an equation HP=Torque X RPM/5252. That's why, when the sanctioning body (NASCAR, FIA, etc,) restricts engine displacement, everybody wants to rev their engines higher. Again for the street I think torque rules. And that's because we spend so much time accelerating and/or cruising at low RPM's. However, in a race car you spend very little time at low RPM even in a road race. So, geared properly, the shorter stroke engine will rev up faster. Like I said, look at a current Formula 1 engine - a little, normally aspirated 900 HP 3.0 litre V-10 that idles at 4,000 RPM and is redlined at 19,200 RPM!!! Just listen to one go through all seven speeds up to 210 MPH in a matter of seconds sometime - you'll be convinced. Maybe a better example is a Harley vs. Japanese crouch rocket! Quote Link to comment Share on other sites More sharing options...
Heavy Z Posted October 26, 2003 Author Share Posted October 26, 2003 Thanks Speedracer for the reminder that race cars with race gearing are the exception. Had I been more specific in my original statement and emphasized certain things more, many of you wouldn't have needed to chime in. Thanks everyone for the input and help in clarifying this subject. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 26, 2003 Share Posted October 26, 2003 Heavy Z - That's not what you started out this thread to be about but........ what happens if the 383 can't rev any higher that 6,000 RPM but the 327 can go to 7,800 RPM? with the same max piston speed (4000fpm, which is normally considered maximum)the 383 would be limited to 6400rpm a 327 would be limited to 7384 rpm Horsepower is just an equation HP=Torque X RPM/5252. true That's why, when the sanctioning body (NASCAR, FIA, etc,) restricts engine displacement, everybody wants to rev their engines higher. they sure don,t WANT to rev the engines higher, in fact it costs a great deal more money to do so! its just that the higher the rpm level is needed for the max power production if limited to the lower displacement Again for the street I think torque rules. And that's because we spend so much time accelerating and/or cruising at low RPM's. car engines are designed with mileage and long maininance free operation, not max hp as the goal However, in a race car you spend very little time at low RPM even in a road race. So, geared properly, the shorter stroke engine will rev up faster. Like I said, look at a current Formula 1 engine - a little, normally aspirated 900 HP 3.0 litre V-10 that idles at 4,000 RPM and is redlined at 19,200 RPM!!! Just listen to one go through all seven speeds up to 210 MPH in a matter of seconds sometime - you'll be convinced. yeah Im convinced...Im convinced...that the rules limiting displacement, car weight, fuel,induction,etc. force the cars to design and run those style engines to be competative. theres not a single team that would not increase displacement or turbocharge if the rules allowed it!! the only reason NASCAR dropped from 430 max displacement to 360 max displacement was to keep the cars from becoming faster than the tracks and drivers/safety tech. could handle you all keep ignoring the fact that the engine can turn increased rpms only as fast as the cars gearing, tires, and weight will allow, if your not limited by class rules, the larger displacement slower turning engine will last longer and produce the same power with less stress on the engine. no one in their correct mind thinks a 19,000rpm 3 liter formula engine will push a car nearly as fast as an intercooled twin turbocharged 555 cid displacement aluminum engine, running 80% NlTROMETHANE 20% toluene (those frequently make over 3000 hp btw) Quote Link to comment Share on other sites More sharing options...
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