70 dart swinger slant turbo build and mild restoration
Bingo. I'd want custom pushrods anyway, for the thickness. I know you can mill .100 off the deck, and a fellow over on .org runs a angle milled head (.200 off spark plug side, .100 off manifold side) and if that don't get you to 8.1/8.5:1 SCR, you can overbore and bump compression by swept volume.
But, by the time you're all said and done, along with reconditioned rods (don't tell me you're gonna cheap on quality!) you're still nosing 1k. Fret not, still even more options. Unfortunately none cheaper.
Stock rods, custom piston
Molnar rods, custom piston (i've heard wiseco piston are thick enough to be machined for a 15-18cc dish)
Molnar/wiseco package, custom thick head gasket
Wiseco piston, stock rod, offset ground/welded stroker crank! (c'mon, don't build no cookie cutter slant!)
Some form of jerryrigging that ultimately leads to a time bomb which is bound to blow
I can't imagine any form of 7" rod paired with any of the forged 'slant' pistons on the market working together to form anything less than 9.5:1. Bill claims his is 9.1. Im NOT saying that he's lying, he seems about as honest as they get, but I'm in the middle of a light weight build (which consists of 7" rods and 2.2 pistons) and there never was a possibility of mine being below 9.8 (and this is with a 58cc head, which is on the larger spectrum of average) if Bill's is 9.1, that may work for him, but I would highly recommend against it on the street, especially with any 'respectable' boost level and the small, min overlap cams that tend to be used in similar builds.
Bill, would you mind digging out some measurements for us? Deck height, head cc? I think wisecos have 5cc dish, and I'm pretty sure you've said .045 over. Piston compression height for the wisecos is out on the web somewhere, and I'll try and dig up to compare to my kb pistons tomorrow. I also remember Fel-Pros being in the vicinity of .038-.039 I think...
Something that *may* be worth looking into is srt4 pistons on 7" rods (i don't remember if there is/was a forged offering for those motors)
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Brandon, I share your concerns about the compression ratio in my motor, but I was very careful when I measured it, in view of the fact that anything over 9:1 could shoot my whole program in the foot. With that in mind, I took special precautions when I broke out the Vaseline, the clear 1/4” plate, the burettte and the colored alcohol.
I measured everything not twice, but, three times.
The Fel-Pro gasket was .024”, compressed. I don’t remember having actually measured the piston deck height, but I carefully cc’d the amount of volume with the piston at TDC.
Added all together, it came out exactly 9:1, and I breathed a sigh of relief.
The head was ported and had big valves, but, was never milled.
The block was given to me by its second owner and was known to have never been milled.
I get away with this because:
1. This car is a race car only; never driven on the street.
2. It is fed a diet of $10.00 a gallon, high-octane racing gas (unleaded.)
3. It is intercooled twice; once with a front-mounted, air-to-air unit and, once, chemically.
4. I use 18 degrees of spark advance, locked plate, maximum. Never sees more.
5. Boost has never been more than 15 pounds.
6. The A/F ratio is 11.4:1 during boost.
So, when I go to 20 pounds of boost, I MAY have problems (detonation-related,) I dunno... and, if not then, even later when I get serious and go to 25 (and, I WILL, if it still hasn't blown-up, by then...)
So, that’s about all I can do to verify my compression ratio, short of tearing it down and measuring everything, again... I’m too old and lazy for that....:banghead:
But, I can tell you this: I did my dead-level best to verify my engine’s compression ratio, using the tools I had learned how to use in Chemistry class and in blueprinting other race cars; I don’t think I made a mistake. If I did, shame on me...
You know, turbo slants use very mild cams (and basically weak valve springs, since that’s all they need, because they only turn 5,500 rpm,) and really have no use for thick walled push-rods. Stock ones work fine with the shimmed 340 springs employed.
And, why in the world would you want to spend the money to stroke a 225 crank; don’t you think four and an eighth-inches is long enough? Boost is available to make well-over 500 horsepower with a stock-stroke 225, and maybe I’m gettin’ old, but, that’s enough for me (in an A-body.)
