Cam design limitations
Bill, What is the bore, stroke, valve sizes, and head flow info for your engine? What about the type of turbo you have? I see what they are doing, at least I think I do... But there may be other ways to keep the exhaust from acting against the intake flow. That MM series lobe has a .535 lift at 235° @ .050 so I think it's close. But that is a very fast ramp speed and I would be concerned about the life of it it in a street environment.
A friend of mine races a 232" Chevy and it's turbo'd on methanol. It makes enough steam to run mid nines. I can't tell you how many mods were done to get the engine capable of making that power. Including him paying for lots and lots of camshafts...lol.
Here is a thumbnail sketch of the mechanical specs of our engine:
Block: 1964 225 slant 6
Head: 1964 225 slant 6
Crank: 1964 forged, ground .010"/.010" and balanced
Block modifications: bored .065" (234 cubic inches); no deck cleanup milling necesssary
Cylinder head was bought
used off ebay from a guy who found it in a VAN, in Las Vegas. The van was in a junkyard, so he never got any information about it, but it was ported (pretty nice port job, my machinist said) and had 1.74"/1.5" valves installed. It came with a set of stock rocker arms, which we are using.
It's never been flowed...
.024"-thick. shim steel head gasket
The cam is a Bullet flat tappet, and I don't have the card handy, but I'm pretty sure it's a 210/210 @ .050", with .484" lift, ground with 115-degree lobe separation. I put it in 4-degrees retarded to kill some anticipated (hoping for the best!) wheelspinning low end torque. That may have been a mistake; we'll see.
904 Torqueflite with the 2.74 low gear, a full manual reverse pattern valve body and a TurboAction reverse pattern floor shifter ($300.00!!!) damn...
3,000-rpm-stall, "bastard" Hughes torque converter ("bastard" because it has early and late internal components to make it fit the early crank snout and late front pump...)
The head had never been milled, so, with some forged, Wiseco flat top pistons, .167" below the deck. The true (measured with a burette) compression ratio turned out to be very close (VERY close) to 9:1. About right, with the 7-inch K-1 forged rods that went with the pistons, as a "set" kind of.... Wiseco works closely with K-1 and developed this
low-drag ring setup piston combination, specifically with the wrist pin set (height-wise,) to work with the long, 198 slant 6 forged rod that K-1 produces.
We filed the ring end gaps to: .020" top,
.024" 2nd.
Blow-thru modified 750 Holley 4150 double pumper with a boost-referenced power valve.
The turbo is a 67 millimeter, Turbonetics, 4-bolt mount unit that came to me from a friend who runs an identical unit on his Grand National Buick (231 cubic inches,) His car runs mid-tens, so he said it should work well on our motor. Our camshafts are very similar in duration and lift.
The header is a 6-into one, 1 5/8", one-off, long tube piece that my partner, Freddie, built. It's nice looking, but I am apprehensuve about the heat that will radiate from those long tubes before the exhaust charge gets to the turbo. Heat is everything to a turbo. I'm sure we'll experiment with a different (shorter) setup, down the road, after we get this monstrosity working... The guy that ceramic coated them said DO NOT wrap this header. He didn't elaborate.
The intake manifold is a long-runner Hurricane from Ausatralia. After the header was built that fits the configuration of that manifold's runners, a very knowwledgable source told me that long runners are very bad for boosted applications and the FIRST thing I need to do, was to get rid of that intake manifold. He was serious, and he's someone who knows what he's talking about, when it comes to turbos.
So, I bought an Offenhauser 4bbl manifold and it didn't come CLOSE to working with that header (runners hit the pipes.)
So, I heard that the Hurricane short runner ($500.00) manifold was a close copy of a Clifford, so I bought a Cliffford. It was better, but still had a considerable amount of interference. We beat the header, and ground the cast runners 'tll we went through to air... still no fit.
I guess we'll start out with the long-runner, for now,:sad7:
We have an oil pan that has had the sump deepened 2.5" and baffles added to prevent oil pump pickup starvation on both acceleration and deceleration.
electric fan
electric water pump
stock oil pump
stock electronic distributor with an MSD 6-AL II (digital)
MSD Blaster coil
Taylor solid core wires
Snowperformance Stage I Boost Cooler meth injector that will be set to start spraying at 3 psi of boost
Walbro 51 psi fuel pump running through 3/8" line to a boost-referenced Mallory regulator set at 6psi for the needles and seats. Two inline fuel filters; one before and one after the pump.
Front mounted intercooler that is rated at 550 hp... Don't think we'll be making more than that... lol!
Sorry this is so logn, but you asked; I probably left something out, but I am a 2-finger typist and am s-l-o-w.... and, I forget...
Thanks for listening!!!8)