Guest HellTriX Posted May 13, 2003 Share Posted May 13, 2003 Hey guys I just got my Z car. After seeing a 240z with a LT1 + supercharger I had to have one. I just rebuilt the carbs on the I6 and took it for a spin "literally". This lil 2.8 has some balls compaired to a 2.8L s10 I had hehe. I was just wandering what the perfomance difference is going to be like when I throw together a small block for it. Was planning on starting small and working my way up. Any 350 core with 10:1 pistons and a mild 224 degree @.050 cam, mildly ported iron heads (stock valves/seats), performer rpm with 750 vac sec carb. Whats that like 375-440 hp? But I will be adding some weight with the iron headed v8 right? Later I will rebuild and throw in twin turbos, but for now I just wanna know if cheap v8 would be worth the $400 bucks for building. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted May 13, 2003 Share Posted May 13, 2003 Couple of things here... You really can't compare a I6 to a "Mild V8" without posting some numbers... Best bet is to save your money and BUY the JTR manual and just read it. A properly built aluminum accessoried V8 Chevy is gonna be within about 38# of an I6 motor and a Small Block FORD will weigh LESS than an I6. So going back to your title of comparing a mild Chevy to an I6, I'd say take it a step further... Compare a bone stock 350 Chevy to a bone stock 2.8L six nissan. The FI nissan motor made less than 170HP at the flywheel. Torque was LOW, in the 120s if memory serves me correctly (Someone with actual #s Jump in...). A stock Chevy 5.7L Truck motor is making about 245HP and about 275FT# of torque and can be bought NEW with a warranty for $1200. This would still require accessories, and a tranny/mounts/radiator/driveshaft, and would outweigh the I6 motor by about 75-100# (With Iron heads) depending on accessories like aluminum intake, waterpump, radiator. However, the BIG advantage is the torque... Look at the difference in the torque numbers... That is significant, and as John Lingefelter points out, TORQUE is what makes you move off the line. Torque wins races and makes you smile after that violent launch at the stoplight. I spent a small fortune trying to make I6 motors run fast. I wished I had started with the v8 kick in 1987 with my first Z... Oh well, live and learn. Hope this helps! Mike Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted May 13, 2003 Share Posted May 13, 2003 TORQUE is what makes you move off the line. Torque wins races and makes you smile after that violent launch at the stoplight. Couldn't have said it any better myself. Been grinning for over 3 years :D Quote Link to comment Share on other sites More sharing options...
Phantom Posted May 13, 2003 Share Posted May 13, 2003 The 1977 L28 made 149 HP at 5,500 rpm at the flywheel with 166 lb-ft of torque at 4,500 RPM. By 1983 the ZX L28 was making 145 HP at 5,400 RPM but 163 lb-ft of torque at 3,000 RPM. The improved head design made the later model L28 a lot gutsier. The 170 HP rating for the '77 was a gross hp rating not including accessory losses. Conversely, if I remember right, a bone stock LT1 will make in the neighbor hood of 245 HP at 5,500 rpm and 350 lb-ft of torque at around 3,200 RPM. Remember, torque=accelleration. Quote Link to comment Share on other sites More sharing options...
Guest Your Car is Slow Posted May 13, 2003 Share Posted May 13, 2003 Engines dont produce horsepower...they produce torque (or a lack of it). Horsepower is merely a number calculated from torque at a given RPM. Quote Link to comment Share on other sites More sharing options...
Phantom Posted May 13, 2003 Share Posted May 13, 2003 And your point is? Quote Link to comment Share on other sites More sharing options...
Mikelly Posted May 13, 2003 Share Posted May 13, 2003 I think it is a universally accepted term to say a motor "Produced" XHP... It is a means to measure by, yes, but the fact remains that saying a motor procudes HP is certainly acceptable... If not, better line up every mot-journalist on the planet... and get a rope... Mike Quote Link to comment Share on other sites More sharing options...
Mudge Posted May 13, 2003 Share Posted May 13, 2003 Not sure what a mild V8 is (245HP?), but TORQUE is the difference. An LT1 as an example, although more expensive than a carbed V8 will have alot more balls, even in a much heavier car. Like Mike said, there is no way to compare them, unless you look at big versus small. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 13, 2003 Share Posted May 13, 2003 An argument from the other side... You folks are forgetting about weight. A daily driver 1970 240Z with an L6 can weigh 2,340 lbs including AC, radio, etc. I have yet to see anyone post the weight for a V8 conversion (including AC, etc.) that weighs less then 2,600 lbs (most folks forget about the weight of the different transmission, R200, bigger radiator, etc.). A simple BSP L6 motor (stock pistons, cam, headers, ignition) making about 200hp and running SU carbs will turn mid-13s in the 1/4 mile at a 2,496 lb weight (including driver), get 24 mpg on the highway driving at 75 mph, and will normally out corner and out brake a heavier V8 conversion. The $1,200 for the Chevy crate engine can be put it into the L6 engine and you can get at least the above level of horsepower and 1/4 mile performance. I'm assuming money spent on suspension, brakes, etc. will be equal in both build ups. A low cost good running L6 is not as slow as some would have you think. Quote Link to comment Share on other sites More sharing options...
Georgia Flash Posted May 13, 2003 Share Posted May 13, 2003 I have but one word to say about the inline sixes, SLOW! I will be very disappointed if my V-8 conversion doesn't blow away all the bad feelings I have had while driving a inliner. I have had three Z cars, 2 ZX's and the 280 that I am currently working on. None of them could compare to a V-8 powered car. I loved the last ZX I owned and almost cried when it rolled out of my driveway in the hands of a stranger. So why did I get rid of it? Lack of power! One night on my way home from work a guy got right up on my ass with a 60's model Plymouth of some type. I accelerated to about 70 to 80 MPH. The little ZX seemed like it was about to blow up the motor was reved so high. When we got to a passing zone, the Plymouth just strolled on by and never looked back. Oh yeah I tried to keep up with him but he just kept on going until he was out of sight. EMBARASSING! I bought an 87 fuel injected Vette with a 5.7liter and went looking for the Plymouth By the way nothing I have ever driven accelerated like that Vette. If you were not careful the thing would almost get away from you when you stomped on the gas. Quote Link to comment Share on other sites More sharing options...
Mudge Posted May 13, 2003 Share Posted May 13, 2003 Comparing my former dual Weber L6 to my much heavier Camaro in itself is a huge difference, and my Camaro is nearly stock currently. I feather the throttle the whole way to work, or I'm off the gas entirely in or out of gear, where with the 240 I was half throttle sometimes to get up hills without lagging. Contrast to the Camaro and again I can feather the throttle in 5th and fly up a hill at 1500+ RPM. Throw it in second and wham, take-off. Between the two cars was about a 2 second difference in the quarter, thats a big friggin difference. 240 just doesn't have the grunt like a V8 does, a V8 in a 240 though must be a blast even if making modest power. FWIW, one of my Korean friends was a Civic and import fan-boy, until his first ride in a Buick GN. Then he later got to ride in a Camaro. He says he is proud to have other asians look down thier noses at him, he now owns a black/black Z28 6 speed. No more rice for him. A torquey engine is an experience to be lived, if it has top end too then all the better. http://www.csboyfriend.com/mycar.html Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted May 13, 2003 Share Posted May 13, 2003 You guys are all wrong. It is the torque at the rear wheels that counts. And as Grumpy says, you build for HP so you can take advantage of the torque multiplication available from GEARING. (I hope I quoted him correctly). From a basic physics outlook POWER is a measure of the ability to do work. Torque by itself is incapable of doing work. The more HP you have at any given RPM the faster you can accelerate at that RPM. Period. End of argument. The thing that confuses people is you have to look the engine HP over the range of RPM's that it is being used. What a broad torque band does do is allow you to produce decent HP over a wide range of engine revs without constantly disconnecting power from wheels to shifting. Let me ask you a question: What is the best way to win a race, by setting up the car to keep the engine RPM’s near the torque peak or near the HP peak? Quote Link to comment Share on other sites More sharing options...
Michael Posted May 14, 2003 Share Posted May 14, 2003 The problem with the torque vs. hp argument (build for hp, use gearing for torque) is the fact that the engine has to spool up to reach the rpms for its “sweet spot”. Engines built for high power, without priority for high torque, almost universally have a power band that favors high rpm. In a racing situation, the driver can plan ahead, by revving the motor before he drops the clutch, pre-positioning the engine in its favored rpm band and preselecting the appropriate gear. In a street situation, off-idle throttle response (and torque!) is what produces the seat-of-the-pants acceleration. I agree that in a controlled racing situation, a mildly improved L6 can achieve similar results to that of a stock V8. But in a street situation, leaving the stop light at 900 rpm or suddenly flooring the gas without downshifting at 25 mph in 3 rd gear, there is no comparison! With an automatic transmission on the street, the difference is even greater, because it takes an appreciable amount of time for the transmission to “realize” that it needs to downshift. The gearing argument is moot if all that the driver desires is a burst of acceleration on-demand. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 14, 2003 Share Posted May 14, 2003 What is the best way to win a race...? Qualifying on the pole and leading every lap... Quote Link to comment Share on other sites More sharing options...
johnc Posted May 14, 2003 Share Posted May 14, 2003 What is the best way to win a race, by setting up the car to keep the engine RPM’s near the torque peak or near the HP peak? Now for the more serious answer: it depends. Drag Racing Gear the transmission so the rpm drop to the next higher gear is right at the torque peak. Gear the rear so that the engine hits redline in top gear at the lights. Get ready to make lots of gearing changes based on actual ETs. Road Racing Gear the rear so that the engine hits redline in top gear at the end of the longest straight (or fastest part of the track). Gear the transmission so that the car will accelerate quickest from the corner that exits onto the longest straight or fastest part of the track. Get ready to make lots of gearing changes based on practice lap times. Quote Link to comment Share on other sites More sharing options...
80LS1T Posted May 14, 2003 Share Posted May 14, 2003 Qualifying on the pole and leading every lap... LMAO!!!! Guy Quote Link to comment Share on other sites More sharing options...
Tim240z Posted May 14, 2003 Share Posted May 14, 2003 Qualifying on the pole and leading every lap... LMAO!!!! Guy Ha ha ha ha .... me too!!! J.C. U smart ass!!! Tim Quote Link to comment Share on other sites More sharing options...
Guest HellTriX Posted May 14, 2003 Share Posted May 14, 2003 Wow you guys are going way to far lol. I do now have the answer though.. A stock V8 will be much funnier than the stock 6. Then the potential to upgrade HP is much easier on the V8. I dont want to change the rear end of my car. Or do I have to? Can someone fill me in on what kinda rear I have? I am pretty sure its an open diff because its way to easy to do the one wheel spin around corners. This is a 1976 280z converted to SU carbs with stock 5 speed. I was thinking of putting in a 700r4 tranny for the overdrive and I can get one cheap. What would be an option for a 4 speed stick shift? Vehicle update: Interior stripped and sand blasted. Floor boards ready for rubberized painting wednesday. Quote Link to comment Share on other sites More sharing options...
Phantom Posted May 16, 2003 Share Posted May 16, 2003 I don't think you want a 4-spd standard. No overdrive. If you have a stock differential it is either a 3.54:1 or a 3.36:1 depending on if the car has a standard or an automatic, respectively. Either way it is an open differential. If you are going to go the 700r4 then find a 3.36:1 R200. It will help keep your rev's down. If you go with a five speed manual with an overdrive the 3.54 will work but again, the 3.36 will probably be better for overall gearing. You will want to investigate a quaiffe unit or finding an R200 LSD and changing the ring & pinion gear if you start making any serious HP. Use the search function onthe forums. You can read until you're cross-eyed on these subjects. Good luck! Quote Link to comment Share on other sites More sharing options...
quicker240 Posted May 16, 2003 Share Posted May 16, 2003 having moved from a relativly well modded I6,tripple 50mm carbs,header,cam,port work,ign etc.etc... to a v8 sbc was a no brainer.going around a banked turn at an autocross event at Talladega GP track at max sweet spot in the rpm range of the I6 and the car just drove around the turn.I WAS PISSED!!! After the v8,I could drive and aim the car with the go pedal and step the rear out at will,and REALLY blast out of a turn.with proper setup the car handles at least as well as before and i think overall balance is even better.steering is heavier but i attribute that to gigantic wheel tire combos as compared to skinny stock 195/70-14 setup.You WILL love the V8.I promise Quote Link to comment Share on other sites More sharing options...
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