Guys just wondering... What mods are needed on a 455 to run forced induction, I.E. 6/71 Roots Blower, or a ATI Procharger, or even turbos. I`ve heard that the clamping force on the heads are adequate enough for forced induction. I was a t a car show today seen a 71 Road Runner ,440, with a BDS 6-71 blower on it with BDS Fuel Injection," very programable and streetable" was added by the owner , he stated that he did low 11`s over 124mph. Looked bad as hell and killer too...... Just thinking hmmmmmm my Regal 455........ :Brow: :laugh: :TU:
Chris, that really depends more on where you are going to take the engine from a horsepower point of view. Let's say you want to build a 455 with 550hp or so. Good forged pistons and ARP rod bolts are a given. You'll also need undercut head studs and TA's "Orange Crush" head gaskets. If you want to go over this level of power, you need to consider a TA girdle. None of thisis any different that what you would do for a strong street engine. The chief differences with a boosted engine is that you will build the engine with relatively low static compression, and a generally much milder camshaft. With the 455's torque, you don't need to worry much about low end grunt with an 8-8.5:1 ratio. Blower cam profiles are generally 10 degrees more on the exhaust side and run in the 112-114 degree range. BUT consult with your favorite cam grinder AND BE HONEST with both yourself and them to get the best results. With our centrifugal kit as an example, an extremely mild 360bhp engine at only 8-10psi of boost you're looking at making 540-600bhp! Michael Tweedy XSPerformance@iwon.com
Chris, I agree with Mike T. As long as you are not trying to overboost the engine, the bottom end can be fairly mild. Of course most guys who start out with a blower or turbo engines will eventually want to try more boost. The better you set the engine up, the more mods or boost you can run later if you desire. If you plan on running 10 psi of boost or more you should really run forged pistons. Most stock style cast pistons are only good to 7-8 psi. Also if you plan on running that kind of cylinder pressure you should think of o-ringing the heads. Good parts are a must to engine longetivity and will save you money in the long run :grin: Thanks, Mike
So what would be needed for a twin turbo, single carb set-up running at 4psi? Could I get by w/hypereutectic pistons if I keep it out of detonation?
Hello, If you only run 4 psi of boost the hypereutectic pistons will be fine. Remember though this is all based on a 8.0-8.5-1 static compression engine. If you are only going to run 4 psi of boost why go through the trouble of running a twin turbo setup? I would think a single turbo would support that fine. Just curious. I know it will look cool:grin: Thanks, Mike
I can get turbos cheap from the wrecking yard and twin turbos simplify the exhaust setup. Besides, I'd have to buy new a single turbo big enough for the 455 which would be $$$$$. I might get forged pistons so I can turn up the boost in the future.
Mike T.... Just curious who does make a Cam for boosted applications? I would like to have the 455 with forged pistons, some type of cam, ARP bolts, maybe even the eng girdle (sometime). So the heads have to be o- ringed even at 10 psi of boost? Still what of the clamping force of the heads? The head bolts per cylinder is less than a SBC,will boost psi like that lift the head? I under stand that the STG2 heads use more clamping force and the block deck has to be drilled to add new holes for more head bolts. Will a mild eng at those boost levels, need that mod? And will a Performer intake be used when boosting? ( thinking in the realm of the ATI Procharger kit your working on. "NEED MORE INPUT":grin: Thanks Just want to start geeting the path started in the right direction for the 1 time purchase and eng rebuild and mods for supercharging.:TU:
I'm not yet at a point where I can give concrete answers about what to do, but I can tell you a few things not to do!!! Hopefully I'm in the short rows and will see some good numbers before too long. I'm so close to the track I can hear them run on Saturday night, so I can't use distance as an excuse! I spoke with someone at Turbonetics about cast pistons and how much boost was safe, and he said he has seen an engine with cast pistons running 20 lbs of boost! I don't know any of the details, but I'm sure everything was working together well in that system! From what I understand, turbochargers are eaiser on the bottom end than nitrous or belt driven blowers. I'm using copper head gaskets (.040 thick) with O-rings in the block and reciever grooves in the head. They are holding up so far, but the .020 thick ones did not. Low 11s with a 455 shouldn't be too hard, considering........ http://www.htc.net/~tbaldwin/66chev.html :grin:
ANY Cam grinder cam grind you a blower cam, just be very honest with both them AND yourself as to what you want to do with the car. But I will tell you, you don't need much of a cam with a centrifugal supercharger! Second, I did not say O-ringing the heads was necessary. That was Michael Kise's suggestion. I feel the TA orange crush head gaskets when used in conjunction with undercut head studs are superior to the FEL-PRO blues and do not really need o-rings at lower boost levels. BUT O-RINGING IS A VERY GOOD IDEA. Third, if you have Stage II heads already, sure use the optional head bolts, but I wouldn't buy the heads just to get more clamping force! Fourth, you can use a dual plane, but a single plane works A LOT better. Easier to tune and much more power. ALAN, I think whoever told you that at TURBONETICS was being perhaps a slight bit irresponsible. I personally would never tell anybody that, because sure enough, somebody will go do it. Your info about supercharging was partially correct. Both turbos and centrifugal superchargers are dramatically easier on the bottom end (they also do not side load the pistons as heavily). Roots type blowers are much harder on the bottom end as they place a tremendous load on the crank snout and require a large amount of power to operate. Nitrous CAN BE brutal on everything because of where in the crank cycle and the way that it delivers its power. Progressive nitrous system can help this somewhat. In a nutshell, the modifications which allow the 455 to live under boost are essentially the same as what you would do to build any 455 with like horsepower. Forged pistons with a compression of 8-8.5:1 File-fit rings ARP rod bolts Undercut head studs TA orange crush head gaskets (with or without o-rings) Main studs Block Girdle (depending on horsepower) And remember detonation is the enemy, NOT boost! That means: Intercooling, adequate fuel system, adequate ignition! Michael Tweedy XSPerformance@iwon.com
