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#81
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. Last edited by quick67bird; 04-21-2014 at 07:13 PM. |
#82
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Dont want to hi-jack this thread, but I guess I can make it official. Sold the Procharger (actually selling). The custom 4 link/watts is all installed. And in a lame attempt to keep on subject, my C/R is 8.95:1. |
#83
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Quote:
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#84
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With all the turbo builds that are going on now I that I would bring this back up. Any updates on any of the builds mentioned here?
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#85
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Ok I am ready to buy a turbo now that I bought a set of turbo manifolds that Jeff Palazzo/turbo69bird used to sell.
My combo is based off a long block Ken Keefer built for me. It is a 70 455 block bored to 4.185 bore SRP flat top forged pistons Block is zero decked Calculated compression ratio is 11.44-1 4 Bolt main caps filled to the bottom of the freeze plugs 4.21 N crank The heads are KRE 74cc Dports with the following flow lift......Intake......Exhaust.....% 100....77.1..........62.6.........81.1 200....150.6.........114.6........76 300....204.9.........152.9........74.6 400....250...........177.9........71.1 500....288.2.........200.3........69.5 600....319.1.........226.6........71 700....336.8.........239.7........70.5 I would like to go with EFI, but may have to start with a blow thru carb. I do have a Victor EFI intake and fuel rails, but I would need injectors, throttle body, and then the software and I am sure there is more I will need for the conversion as well.
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#86
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If anyone on the board is a dealer let me know as I don't mind buying from a fellow member, but at the same time since this will be my first turbo build I am not looking for an all-out race turbo.
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#87
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A Turbo and a engine with 11.44 compression ratio is not going to be happy or live very long with even low boost.
You should think about swapping out the 11.44 to 1 pistons for some 8.75 to 1 pistons. The lower compression ratio being needed, in that once you experience boost, you WILL turn the boost screw up. There are several on the PY board that will testify to that statement. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#88
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I know the new LT1 Corvettes are at 11.5-1 and I have seen a lot of those guys boosting those engines. How are they getting away with that? I know it seems like those engines would not work with boost. I have one of the new Corvettes and have resisted a supercharger because of how high the compression ratio is. Thanks for all you help Tom in answering my silly questions, but I do want to learn.
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#89
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Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#90
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Compression ratio does not matter, cylinder pressure does.
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#91
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1) What are your actual goals for the project?
I drive the car on the street a bit to cruise nights. I used to street race a lot at one time, but where I live there is not too much competitive street racing happening. I am going to try and do some no prep racing and then there are some races that use a street racing type format being promoted up here that I would like to do. I am planning on an IA II build with a 4.25" bore and either a 4" or 4.25" stroke crank in the next year or 2. I got a deal on some Ross 42 cc dish pistons that I am planning on using for that build. I was trying to use what I had until I got my aftermarket block. Kind of trying to use this engine as a learning platform. 2) What is your budget to do the project properly? Pistons, different calibration, different fuel system, Fabrication work to properly mount the boost system under the hood. Upgrades to the other components once you start tearing up parts with the boosted power. While I do not have an unlimited budget I do have a good amount I can spend. Depending on the price of some parts I may have to save money, but I probably have $5,000 available right now. I have a nice set of turbo headers that were built by Jeff and they are set up for a single turbo, but I could probably modify them by cutting the driver side header and welding a T6 and a wastegate flange on it. I could buy more pistons for this engine, but will probably wait until I got an aftermarket block. I will probably go ahead and use my NOS system for this engine if it looks like the turbo deal is not feasible. I have the ability to fabricate what I need with all the welders I have. I am a Millwright by trade so it I do a lot of fabrication. I have a pretty beefy 12 bolt rear end for my car, but I would like to get a Rossler transmission if I could. I do have a nice turbo 400 now, but I am sure that will only last so long once I start really building HP. The car has a 10 point cage in it, but it will only cert to 8.50s since as it is mild steel. I hope this in not too bad of a read. Let me know if you need any more information. Thank you, Robert
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#92
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Also post up the new slang words used around the local Drive-In: "My Pressure per Crank Angle Degree is bigger than your Pressure per Crank Angle Degree." Much more useful for the average first time Boosted Engine Guy to say: Charlie66 has a 8.75 to 1 Compression Ratio engine with XXX Turbo Camshaft and YYY volume cylinder heads, with ZZZ head gasket and BBB dish volume in his pistons and can make 750 hp with a 194 cid Pontiac engine at 35 psi of boost pressure. How about we have a vote (poll) on which way is more useful for the typical Boost Guy. Tom V. MILLWRIGHTS ROCK!
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#93
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Type of fuel appears to be e85. But even if pump gas you are probably best off with a conservative compression ratio. Keep in mind boost psi and charge temp greatly affects what ratio you can run safely.
Pump gas under 8.5:1 with iron heads 9.5:1 with aluminum heads can be safe if you arent going for 30+ pounds of boost. At lower boost levels you may be able to run higher compression than this and many do. E85 allows more compression. See quite a few on YBs forum pushing 10:1 or more with aluminum heads. Personally I'd rather turn compression down and run higher boost. Transient response and spool up are a reason some opt for higher compression but smart turbine selection and cam choices can accomplish the same thing. If you are doing a motor in the future and want to run your current signature engine with a turbo or two you have some options. Instead of buying dished pistons just find some large chamber 455 heads(115-124 cc) and put decent valves and stiffer springs and good gaskets. A single S475 for now and add a second one on the new motor. I suggest a good a/w intercooler now and re-use it later. Your new motor...4.25 bore or thereabouts will hold gaskets better than larger bore. Stroke... 4" with 4.25 bore = 454... 4"x4.255=455... 4.25 x 4.25 = @482 tough call. I think you should start a new thread ..."Build my motors" Yes even with stockish heads a single s475 is going faster than your present combo. |
#94
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Thanks, Bruce that is a lot of good information for thought. I think I am just going to use my nitrous for now and buy what I need for my aftermarket block as I go along. I really appreciate the help. I have been researching this subject quite a bit and I respect all of your opinions. When I get deep into the build I will be consulting Travis and Rodney.
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#95
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1) A question asked often. How much power is a FULL POINT of compression worth in a real world application. (example 8.5 to 1 vs 9.5 to 1) Most experts say 3% on average. So that means your 1000 hp engine gained 30 horsepower by going up a full point in compression or 15 horsepower when you go from say 8.75 to 9.25 to 1 compression ratio. But now you find out the engine is sensitive to timing changes even with E-85 fuel. 2) Another rule of thumb is the boost world is that if you increase the mass flow thru the engine by 2 times you double the horsepower. So say your Pontiac makes an honest 500 hp at 6500 rpm with some mass flow number. So you boost the engine to double the mass flow thru the engine and you make 1000 hp but at 5900 rpm vs 6500 rpm. Less stress on the engine components, a longer push on the piston, and the engine makes lots more torque at the lower rpm. 3) Little firecracker little bang! Big firecracker BIG bang. Many people miss the fact that the lower compression ratio obviously means that there are more Cubic Centimeters in the combustion chamber to store fuel and air for the next combustion event. A Boost Guy told me one time, I would rather be a full point too low on compression ratio and be soft on the leave but make big power later on in the run vs being 1/4 of a point to high in compression ratio and hurt the engine. Charlie has beat the crap out of his engine at high boost vs what many will ever run but always followed a few simple rules of thumb. Lower Compression Ratio, conservative timing, control of the combustion process using fuel and proper spark (EFI/ignition system) and a good match on the turbo. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#96
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After talking with you and Bruce I have decided to use my NOS for now and build an aftermarket block when they become available.
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
#97
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When you talk to Rodney and Travis, (especially Travis) since he told me he has been so busy with his business work he has not talked to Rodney in 6 months, ask Travis about his 'current opinion' of the ideal cubic inch displacement of a Turbocharged Pontiac these days.
You might be surprised at his answer. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#98
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#99
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Agree, Travis has brought a lot of skills to the Pontiac community over the years, for sure.
Fabrication, Engineering, Calibration skills, etc etc. And a really nice person to talk to. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#100
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I have a call into Travis, but have not heard back from him yet. I will try to get a hold of Rodney as well. I think for this year I will be throwing my NOS system on the car and see what I can run with it.
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67 Firebird 467 cubic inches 7.71 @ 92 in the 1/8 and 11.69 @ 115 in the 1/4. |
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