|08-12-2012 08:26 AM|
My "little" 350 with a 6-71 seems to be pretty happy cruising the streets and highways for the last 20k miles or so. i drive it rain or shine and have even driven it in the Minn snowy winter. 2x 750 dp work great. I have worked with them for a long time and now get 16 mpg aver and I have hit 17 several times for extended drives. I run on 87 to boot.
It's pretty hard not to make 500+ hp with a 6-71 on a sbc. Compression ratio is the biggest hurdle.
Now just to get a couple of posters corrected......there is quite high vacuum under a 6-71 or any positive displacement blower. there is also higher than normal vacuum directly under the carbs all the time. maybe an inch or more.
Boost will come instantly if you jump the throttle however if you are gentle there will just be a reduction of vacuum. Much of the cruise power comes from the very good fuel atomization and great fuel distribution the blower provides by thouroghly thrashing the fuel/air mix. Granted there is some heating of the mixture but this is not all bad as along with this there is little or no puddling of fuel in the manifold that you get with hot cam and low revs NA. Often the idle improves dramatically. My motor used to idle at 1100-1200 in neutral and was barely drivable in heavy traffic. Now it idles at 750 in gear just like any other car on the road. I can sit in traffic as long as necessary with the AC on. There is no Detroit roll ever.....the mark of poor tuning...save it for the Pro Mods...ugh.
|08-10-2012 10:43 PM|
|bigdog7373||Jegs sell a kit by vortech for sbc. Supports up to 950hp, complete kit with everything included. Only $1900!! Its a freakin steal!|
|08-10-2012 07:45 PM|
For 500 hp the 144 was not the blower I had in mind.
It can make 500hp but you have to step on it pretty hard.
A larger blower works better for that power level, on pump gas.
(less heating of the air charge)
The 142-144 blowers really shine in the 430 to 480hp power level.
Water/methanol injection would allow you to push it to 500hp on pump gas.
I had the 177 blower in mind.
|08-10-2012 01:54 PM|
1 word: forced induction.
A 144 blower will handle 500 horses easily.
|08-10-2012 10:57 AM|
Whats wrong with a supercharged motor that runs on pump gas?
Its a very practical way to get a reliable 500+HP out of a street friendly 350SBC.
|08-07-2012 09:06 PM|
Get rid of your engine guy if he told you a supercharger is full boost all the time and a turbo is only making boost when it's spooled up. A supercharger makes more boost as the rpm's go up also, and can be underdriven to whatever your engine can handle.
Neither will work if the static compression of your engine is too high to start with. And forget fuel economy completely. If you're trying for 500 HP you're kidding yourself to even think economy.
|08-07-2012 07:24 PM|
|vinniekq2||Silverado, make your own board. Have comparisons of turbo and super charger and see which one best suits you. To hi jack a board and change the subject you are likely to get poor results due to confusion. aDDing a compressor after the engine build is rarely as successful as planning one before the build,,,|
|08-07-2012 06:02 PM|
|08-07-2012 04:17 PM|
I too, am trying to reach the goal of 500+ hp. I have a 95 K1500 (Silverado) that I'm turning into a "project". I have had the motor pulled, block bored 30 over, forged pistons, an "rv" cam installed, heads shaved slightly (though I am replacing them with Vortec heads - didn't plan ahead) and headers installed. I have dual 2-1/2" lines thru two high-flow cats into a Flowmaster dual inlet / dual outlet muffler, exiting duals out the rear. I also had the auto tranny replaced with a manual.
Unfortunately, the truck isn't running correctly. When under load and in high gear, I'm getting detonation. Could this be the heads? The more I read, the more I'm thinking it is...
My goal was to add a supercharger to achieve the approximate 500+ hp. What I lack in is direction, alas I come for advice from people that know all the in's and out's of this area.
Should I go for a better fuel injection (TPI / MPI) or stay with EFI?
Should I ditch the fuel injection and go carb? If so, at what cost to fuel economy? LOL I know, 500 hp and worried about fuel economy? Well, I do wanna maximize whatever I may get.
Should I look into stroking this motor?
Should I supercharge or turbocharge? The guy who did the motor seemed to think turbo so that it would only "work" the motor when needed, not like a supercharger would from start to shut off...
Long post, I know... just need a few answers and a place to start.
|08-06-2012 11:57 PM|
It's been said that you can only choose two from the three options:
• build it fast
• build it cheap
• build it reliable
So going fast for cheap- for very long, anyways- is a REAL trick. To pull it off requires the kind of knowledge and intuition that only comes from experience.
If you want a dependable engine w/a long life expectancy, build it around an aftermarket block, crank, rods, valve train, heads, ignition, and induction/exhaust systems. The more stock or low end parts you use, the less potential power or reliability will be the result.
Power is in the cylinder heads. Reliability is in the valve train and short block, and should be as stout as your hp goal requires, not just what your budget allows. You would be better off lowering the hp goal to a number that matches the budget than to try to push the limits on cheap. For instance, I'd consider aftermarket rods as a necessity at 500 hp levels. And a 4-bolt bottom end, preferably splayed caps. But after doing that to a stock block, you're getting close to the cost of a Dart aftermarket block that will be stronger than ANY production SBC block. Obviously a forged crank and pistons are advisable- but not an absolute necessity. Keeping the tune correct- as in NO detonation- is as important as anything else you may do.
But in the end, I find myself wondering... why 500 hp? What makes THAT number the target? Because I can tell you from experience as can others here, that making 500 hp is the easy part. Putting that hp to the ground effectively is harder and more expensive in many cases as just building an engine that makes 500 hp.
Be realistic. Set obtainable goals based on a realistic expectations. Because if all you do is build yourself a bad-A 500 hp SBC w/o any plan as to what you are really going to do w/it is not a plan. It's a whim.
|08-06-2012 06:36 PM|
|against all odds||P.S. This is like going running with wal-mart shoes vs. higher quality ones such as New balance, nike etc.|
|08-06-2012 06:12 PM|
|against all odds||
Even some of the bowtie blocks can be built with 400 or more cubes.
|08-06-2012 06:06 PM|
|Ripper 410||I agree with vinnie what is your budget and what is your app.??? what year and type of block are you starting with????? also how do you want too use it , daily driver, weekend warrior, or just a cruser???|
|08-06-2012 05:52 PM|
you guys mention an extra grand laying around! The DART SHP block is 1600.00 (not including the 100.00+ s/h) and the DART little M is like 2500.00 (again not including s/h). Unless you are planning on running over 600hp or planing on running a 3.875+" stroke then I dont see the point. for the extra money you spent on the block i could tear down the motor, buy another block, have it machined and likely buy a few rods or the crank to replace the one that broke. Im all about saving the extra cash to make sure you do it right, but i dont see where an aftermarket block is needed.
to the OP, a 350 making 500hp NA isn't too hard, but one making 500hp NA on 93 or less octane is. it will want to turn some rpm, so a decent forged rot assy will be needed (IMO) you will want to push the limits with compression, say 11-11.5:1 with alm heads that have around 210-215cc intake runners, spend the extra cash and have them cleaned up, 112LSA hyd cam with around 245° @ .050 and .575" lift, use 1.6 rockers to bump you over the .600" lift mark. use a single plane intake like the vic jr, and a 750 double pumper. matched in a 3500lb car with a 3spd (th400-350), 3600-4000 stall and 4.10's to 4.56's.
It wont be as much fun on the street as it will on the track, but you should be able to get it to run on 93 octane.
|08-06-2012 11:55 AM|
|zildjian4life218||do a search on this forum... this question gets asked about every other week. Then come back with a better list of intended use, parts, car, budget and we can better help you get parts lined up. Right now its kinda like shooting from the hip.|
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