wallaby Posted January 22, 2011 Share Posted January 22, 2011 I'm doing more math trying to figure out what my goals are. If my car weighs 3900 lbs, the online calculators say I need just over 500hp at the wheels to run a 11.50 et. My question is how much hp is lost in the drivetrain? How much flywheel hp would I need? Quote Link to comment Share on other sites More sharing options...
Mom's Car Posted January 22, 2011 Share Posted January 22, 2011 The chart on the following page let's you plug in either wheel or crank hp http://robrobinette.com/et.htm Quote Link to comment Share on other sites More sharing options...
wallaby Posted January 22, 2011 Author Share Posted January 22, 2011 I've seen numbers from 10 to 30% lost: This link assumes 17%....I guess that's close. Thanks. Looks like about 580 flywheel hp needed to get to the magic 11.50 et. That gives me a ballpark. Now I wonder how the relationship of torque & hp figure in. I would assume that bigger torque numbers would be a plus...for example a small block and a big block with the same hp numbers; wouldn't the higher torque values of the big block be an advantage? Quote Link to comment Share on other sites More sharing options...
AL M Posted January 22, 2011 Share Posted January 22, 2011 Remember, thats a perfect senario, when all the planets are in alignment.... perfect air, suspension doing its thing and of course if you hook. Steve and I are the exact situation that you just mentioned...I hope we all, including you, reach that 11:50!!! Lots of luck!! Al Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted January 22, 2011 Share Posted January 22, 2011 I've seen numbers from 10 to 30% lost: This link assumes 17%....I guess that's close. Thanks. Looks like about 580 flywheel hp needed to get to the magic 11.50 et. That gives me a ballpark. Now I wonder how the relationship of torque & hp figure in. I would assume that bigger torque numbers would be a plus...for example a small block and a big block with the same hp numbers; wouldn't the higher torque values of the big block be an advantage? Mark are you going to try it with the 454 or are you going to stroke it? With a heavy car torque starts the race and horsepower finishes it. My 502 came out just about square, 654 tq and 656 hp. Like Al said the motor will give you the opportunity but you have to put the other pieces in place to make it work. I think your 580 is close, at least something around 550 with some good suspension tweaks. The loss numbers are going to be influenced a lot by how your converter is working. That's a good goal and would be a fun project....Davey Quote Link to comment Share on other sites More sharing options...
Heckeng Posted January 22, 2011 Share Posted January 22, 2011 Some more food for though. . . It doesn't just depend on HP for a specific ET, it also depends on how the driveline is set up and good conditions like mentioned already. Take Al's new engine. If you have a high hp SBC that is not the highest on torque and you use a torque converter that isn't high enough, he will bog off the line and that will slow his ET significantly, BUT his MPH will be nearly identical to if he had a higher stall that got the engine right in the desired power band off of the line but his ET will be MUCH better. As another example, I raced my car with street tires once a couple years ago and It spun off the line so I just stayed in the throttle for fun and it quit spinning half through second gear (tracks are slick when using street tires) and I ran a 13.3 at 106.XX. My best time with slicks and hooking up well is 12.64, also at 106.XX. I just thought that was really interesting. I was moving forward the whole time I was spinning, but id didn't make much/any difference in MPH, only ET. The moral of the story is that Torque is your friend off the line if you hook and are in the powerband, and if you want the best ET (i.e. 11.5), it will help to have your converter and gears matched up decently to your engine. Does your car have AC? Quote Link to comment Share on other sites More sharing options...
680HPStroker Posted January 23, 2011 Share Posted January 23, 2011 All those online calculators out there should be used for nothing more than a ROUGH gauge. There is is no majical formula that applies to every car. Check out guys with setups that consistantly run where you want to be and go from there. Quote Link to comment Share on other sites More sharing options...
Winston Wolf Posted January 23, 2011 Share Posted January 23, 2011 My cousin has a 68 GTO. 455 Pontiac that he shifts at 5500. Engine dyno'd at 505 HP. Chassis dyno'd at 418 HP, so about 18% loss. He has a turbo 400 with 4.10 gears, 3500 stall. It runs 11.50 at 115 every single pass. I would guess the weight of the car around 3600 as he has a glass hood. Proves that with enough torque, you can get it done. I think 580 HP is more than you need unless the car is a tank. Quote Link to comment Share on other sites More sharing options...
wallaby Posted January 23, 2011 Author Share Posted January 23, 2011 No, this is all hypothetical. My original engine is getting tired. It's already .o60 over so it's either time to get a sleeve or two, or cut my losses and go with a new block. I just figure if I'm going to all that trouble I might as well get a new block with more cubic inches. Instead of running a "small" big-block with lots of camshaft, I figure on going with a mildly-stressed large cube motor with a mild cam. I'm hoping it will have good street manners, work my power brakes, and still be able to take my car to a neighboring state for a meet...and pound out some good dragstrip numbers if called upon. Right now I think I have settled on a 540 cube engine (620hp/680 tq) as my dream engine. I'm almost worried that I might have to tone it down a bit if I want more than one dragstrip run. Maybe it's overkill? Maybe I could choke it down with oval-port heads. Hopefully I won't have to ditch roller rockers to keep my low valve covers because yes, I do have AC. It's all just a dream, but it's fun to think about. Quote Link to comment Share on other sites More sharing options...
Mom's Car Posted January 23, 2011 Share Posted January 23, 2011 You can always go with a .070 over piston. I did that with my last rebuild. With a stroker crank it winds up at a 498 cu in. It dynoed at 624 hp and 634 torque. Quote Link to comment Share on other sites More sharing options...
wallaby Posted January 23, 2011 Author Share Posted January 23, 2011 Hmmm....time to start thinking again. I thought .060 was all the block had to give. I guess I'll have to have it sonic checked and measured to see if it'll clean up with a .010 bore from where I am now. Again; I wasn't aware that a .070 piston was available. Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted January 23, 2011 Share Posted January 23, 2011 if it's a good block (no excessive core shift) it will go bigger than .060. I'm not sure how you're going to get that kind of TQ/HP relationship, it's pretty rare that TQ will exceed HP in this kind of build. If you go 540 you're going to need either a GM 502 or something like a Dart Big M block. There are tons of rotating assemblies out there for doing the 498 if your block checks out okay, that is certainly going to be the most economical route. I have a friend with a 3750 lb Corvette with a very streetable 498 (I mean he drives it everywhere) and he runs 10.80's through the mufflers. It's probably a 10.50 car if he wanted to play with it but he doesn't want a rollbar. A cam in the 230/low 240 duration range with around 600 lift on a 110/112 LSA will bring it to life and still have some brakes. These motors like lift, Lunati makes a very nice cam that's in the high 230's with 600 lift that would be ideal. As far as heads, don't you have some Merlins? Maybe I don't remember correctly but if you do what are the spec's? There's a guy out of Colorado that gets some pretty big numbers reworking stock GM heads so there are options out there. Like I said Mark, would be a fun project and you don't have to run them hard to get good performance, the Velle never sees anything over 6100...... Quote Link to comment Share on other sites More sharing options...
502ci Posted January 23, 2011 Share Posted January 23, 2011 I have a friend with a 3750 lb Corvette with a very streetable 498 (I mean he drives it everywhere) and he runs 10.80's through the mufflers. Was that a mid to late 70's Vette with the driver in it? If not that is one heavy Vette... Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted January 23, 2011 Share Posted January 23, 2011 Originally Posted By: CrazyDavey I have a friend with a 3750 lb Corvette with a very streetable 498 (I mean he drives it everywhere) and he runs 10.80's through the mufflers. Was that a mid to late 70's Vette with the driver in it? If not that is one heavy Vette... I wanna say it's around a '71..something like that....yes, with driver...it's a beautiful car and fully loaded, air and all that stuff...oh, and he did that with 3:36's.... Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted January 25, 2011 Share Posted January 25, 2011 My block is bored .100 over, no issues. JE and SRP have "off the shelf" Pistons in .100 over sizes Quote Link to comment Share on other sites More sharing options...
Mom's Car Posted January 25, 2011 Share Posted January 25, 2011 if it's a good block (no excessive core shift) it will go bigger than .060. I'm not sure how you're going to get that kind of TQ/HP relationship, it's pretty rare that TQ will exceed HP in this kind of build. If you go 540 you're going to need either a GM 502 or something like a Dart Big M block. There are tons of rotating assemblies out there for doing the 498 if your block checks out okay, that is certainly going to be the most economical route. I have a friend with a 3750 lb Corvette with a very streetable 498 (I mean he drives it everywhere) and he runs 10.80's through the mufflers. It's probably a 10.50 car if he wanted to play with it but he doesn't want a rollbar. A cam in the 230/low 240 duration range with around 600 lift on a 110/112 LSA will bring it to life and still have some brakes. These motors like lift, Lunati makes a very nice cam that's in the high 230's with 600 lift that would be ideal. As far as heads, don't you have some Merlins? Maybe I don't remember correctly but if you do what are the spec's? There's a guy out of Colorado that gets some pretty big numbers reworking stock GM heads so there are options out there. Like I said Mark, would be a fun project and you don't have to run them hard to get good performance, the Velle never sees anything over 6100...... I think Davey is right on the money. His desciption is basically my motor. .640 int lift .620 exh lift duration of 230 and 239 and a 114 lobe separation. Brodix Race Rite Rect Port BB 2 Plus CNC. 10 to 1 comp runs smooooooth. Good Luck on the Build. See attached link to my dyno sheet Quote Link to comment Share on other sites More sharing options...
CrazyDavey Posted January 25, 2011 Share Posted January 25, 2011 here's the link looks like our HP and TQ peak at about the same times....my 502 is 656 HP @ 5700 and 654 TQ @ 4700....nice motor Greg.. Quote Link to comment Share on other sites More sharing options...
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