ok, here's my dilema, i was going to build a 350. i already have billet rods and i stopped weisco from finishing my custom forged pistons and my stock crank was going to be turned down and nitrated to work with these rods,my block is at the machine shop and everything is pretty much ready to go. My goal was anywhere from 800- too 1000hp, then i started thinking what if this thing blows up, what if i can't get it to make enough horsepower with the heads that we're all stuck with ect ect. so then i started thinking about a stage 2 headed 455 with a turbo. I thought about just re-ringing it, putting the good heads on it with a cam motion cam single plain intake and turbo with a blow through. just keep the tune way conservative and low boost, until either the iron block or the aluminum block comes out. how long do you guys think a 455 with last at around 700 hp with a stock bottom end, with all the oiling mods. Say i keep it from spinning past 5100 or 5500 rpm. do you guys think i should try this or do you think i should stay with the 350? o No: Give me some of your thoughs. cody
My thought: You'll need a girdle. I don't know enough about the "structural" aspects of the blocks to give you a valid opinion. But I would think that by the time you got done beefing up the 350 block, you wouldn't be far away from the cost of the 455 block. If I had more $$, I would have done this exact thing by now- since my motor is already fuel injected, it would be (relatively) easy to add a couple of turbos. I also already have a girdle, some pretty beefy pistons, rods, and so on. I think that I would limit the motor to about 8 or 10 PSI at most- partially because I could go sans intercooler, and partially because I'd be afraid of blowing the block apart. Once that is done, in a few years when you get your mega-block, you can add your intercoolers and crank up the boost. But by then, you'll have sorted out all of your other problems like tuning issues and how to keep your tranny & rearend in one piece. I think you are on the right track limiting the motor to 5500 RPM. And Stage II heads would be ideal because of the extra exhaust flow. On my "dream" engine, I would probably still not use any intercoolers- instead just turn up the boost to about 15 PSI and inject more nitrous to help cool things down (like a 250HP shot). The turbos could just be a pair of Grand National turbos (mmm, love the sound). One more thought: I'm a big fan of fuel injection if you are considering turbos. I don't forsee getting a winning lottery ticket in the near future. Therefore if I was still able to get my way in a more realistic sense, I'd go with a supercharger from www.xsperformance.net instead of the turbos- it is much easier to install and operate. You don't need nearly the custom exhaust work, and you don't need to violate your engine's oiling system. The downside is that it just doesn't have that way-cool sound, or the exciting kick in the pants from the turbos (which other people would call lag). Have you thought about supercharging your 350? -Bob Cunningham
alumimum rods and a girdle would be a must, with a large frame t6 flanged turbo and decent alumimum heads a blowthrough 850 you will have no problem making 900+ on 10 lbs.
how long do you think the bottom end would last though (stock) on the 455 if i kept it at 5000 rpm or under, until i could get a new block. (by the way whats going on with the cast iron block anyway?) I think it could easily make the power with good heads and turbo. cody
Why aluminum rods? As long as he keeps the RPMs down, I wouldn't think that he needs aluminum rods. -Bob C.
I say go for it! A girdle is a good idea, as are aftermarket rods and custom turbo pistons. The stock crank may well be strong enough if it's prepped correctly. I'm using .040 copper head gaskets with O-rings in the block and receiver grooves in the head and it seems to work well. I still have stock rods with speed pro forged pistons, but I've already collapsed the skirts. I think that happened because the tune was way off, but I'm not 100% sure. If you keep the boost low and the Revs low the stock bottom end may last a while as long as it's not damaged to begin with. But with the stock bottom end you'll need to resist the urge to increase the boost, because it will wake it up! :Brow:
the aluminum rods will give some cushion to the crank and be more forgiving to the already stressed block I agree steel rods are fine for the rpm but at the bigger power level it would be wise to give it every advantage.
I was thinking the only actual motor work would be just to re ring itand oiling mods. I don't really want to spen alot of money on this motor just set it up for an aluminum or iron block. i think it should makes tons of power with stage 2 heads and the right cam and turbo. i know it'll fly apart eventually. over on turbo mustangs.com there is a guy with an all stock bottom end 302 (crank, rods,cast pistons)that ran 142 mph in the quarter and never went above 5200 rpm. his is still together. o No: I know that the stock pistons are pretty heavy but i just thought if the revs were kept way down it might have a chance. cody
It's only money... I say try the 350 but use a good set of light pistons and capscrew rods. Don't turn down the crank since you will need the strength to deal with the power. If you keep the rpm's down then the capscrew rods should holdup. Rpm kills Buick rods more than anything so set aside those fancy rods for a N/A setup. Going the turbo route will cost some coin and building a proper 455 will cost extra when you start to looking at aluminum heads and block prep. It is possible that you will run into head gasket issues under boost when you start to lean on that 455 too. Build a 350 with a turbo setup to run off the exhaust manifolds. You should be able to get close to what your looking for with a blow-thru combination and a little water/methonal to cool thing down under boost. You will spend plenty getting the car, ignition, fuel system, and driveline to handle the power so I wouldn't look to build and tune a 1000hp turbo car as a starter combination. The more you spend to build it, the more it will cost to fix when the tuneup isn't right. You can always swap over the turbo and fuel system to a 455 at a later date once you abuse that 350 for a while without wasting a lot of money into the 350 motor. :TU:
I thought Billmah proved the 350 Buick block was able to handle 1,000HP http://www.v8buick.com/showthread.php?t=68183
I speak from experience, the stock cast pistons will not stay together. My second turbo set up used a stock crank, halo girdle, stock polished rods with ARP bolts and speed pro pistons. I smashed the ringlands on two pistons at 7 PSI boost with 8.8 compression. I had to install the Halo girdle because when the first motor was inspected the main caps were moving around. This time its all out with a TA girdle, H-beam rods, CP blower pistons, etc. On the plus side you cannot beat a turbo for a fast street car. Mine idles like stock has 220 degrees intake duration and put 637FTLBS of torque on the ground. The 350 has a lot more metal on the bottom end and with good rods and pistons it should work nice, either the 350 or 455 turbo setup should be a great project. Good luck. Brent
You can put a ics titan head gasket on it and then you wont have to worry about anything thats what I plan on doing. the ics titan gaskets are the way to go. :beer
