Hey there

What about using the 198 rods and destroke the crank 0.30 and using big metric pistons... 3.520 bore? that'd result in a 232 CI slant with 3.520 bore x 3.98 stroke (.30 under /2 to figure stroke)

do you see any advantages for high redline targeting or I'm getting on the stupidly theoretical side of reasoning?

rod ratio would be 1.78 (ballpark)

Edit: I plan on high revving engine wich would allow a good top speed and use 3.54 or 3.81 rear end...

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

One problem I see... the length of the rod doesn't determine the stroke, the offset of the rod journals from the mains (crank centerline) does.

the problem is that my fingers are in drive while my brain is in reverse

I meant "using 198 rods AND destroke...." so you can use less compression heigh pistons, reduce drag, and increase rod/stroke ratio even more than just using 198 rods on a normal 225 crank.

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

And the advantage of making the engine smaller is???

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Not talking about making it smaller. just in the process of aughmenting the displacement, loosing 8 CI for increasing the rod ratio differencie between the 198 rods and the original rod.

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Your talking about reworking the crank to make it have a shorter stroke?
Is should let you rev higher if it can breath and make more power, but if your going to rework the crank why not make it longer and get more cubic inches and not rev as high and make the same HP as the destroke but with more torque?

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

actually this thought comes from reading your post about the exact opposite proposition as mine. You got this right, I was talking about making the stroke shorter so it can rev higher. My line of thinking was to increase as much as possible rod ratio while not pusinh so over the edge the CR with the piston choice... I know that a .30 destroke or overstroke ain't that big diffrence... but... the higher I rev, the wildest I can go on rear end ratios, so I can keep a good top speed while having a greater torque multiply factor (rear end ratio) so an apparently "weaker" low end grunt on a revver can be turned into more low end grunt by gearing the rear higher.

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I would think you'd want as much low end torque with low (numerically) rear gears and low rpm as possible. I've had hi revving Datsun straight 6's that revved to 8,000. I preffer my current 4,200 redline (it wouldn't hurt to rev past 4,200 but it wouldn't do any good.) just my 2 cents

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64' Valiant Signet 5.9, 64' Dart 170 moredoor 3.7, 67' A100 3.7, 00' Dakota SLT 4.7

I wonder what effect on fuel mileage a low cubic high rev engine v.s. a high cubic low rev engine would be. Lets assume that there 1/4 mile times are the same.
I would think that the high rev. would get less mileage.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

If you want a high reving "tall block" SL6, build a 198.
You can get the 198 to be almost "square" in terms of bore to stroke. (3.64 stroke)
See this post for dyno numbers:
http://www.slantsix.org/forum/viewtopic.php?t=18685
DD

mileage? since when that's an issue? If I were concerned about mileage I'd get a ricer, not a real car. I'd think that under cruise condition they'll pretty much guzzle the same amount of gas, and I'm almost 100% positive that city mileage would be better on a high geared combo.
I'll happily trade a heavy 906 slant block for a 198 crank! We didn't had that flavor. I have a good set of 198 rods and I was trying to figure if this would be a good buildup or a "nonsenser"
BTW those dyno numbers are amazing, I recall having read that post, you're a genius! VE is always above 100%
I don't like low numerical rear end ratios. They feel sluggish until the engine is at certain sweet rpm spot. Mileage around town sucks, and if you try'n beat a eurotrasher or ricer, the amount of time that takes to increase speed is forever! My present mill revs up happily past 5500 (runs kind of out of breath at about 5000 rpm gradually, but it revs.) and I like it. My only fault with this engine was lobe profile, excess of duration without corresponding increase of lift (because I thought that a stocker lift would rev sooner and with less valvetrain wear) and I got kinda cold feet when I did the head. The revving allows a theoretical top speed of 224 km/h using 205/70/14 tires... but... how often do I dun in excess of my cruising speed of about 90 to 110? never... so I thought what about loosing 20 to 40 miles top end speed and build an engine capable of revving till say 6000 rpm and use a high (numerically) rear end? using the same tire configuration, gearing from 3.07 (my present axle ratio) to 3.31 (next gearing avalible) I loose 10 mph, geared 3.54 I loose another 10 mph, I have had a 3.81 geared slant and I didn't like it (ran out of breath before crossing the light, hehe) so I think that 3.31 or 3.54 are the best choices. The 3.31 ratio wrks very good with my low first trans ratio of 2.6 (close ratio 833)

enough nonsense...

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I guarantee that you can already rev a 225 crank higher than 198 rods are safe to go.

You can do all the fiddle-fukking around with the bore/stroke you want, the power is in the head.

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Official Cookie and Mater Tormentor.

yes... I'm working on another head now, and I have a couple of questions about the porting and some related things I've been doingm there will be posted soon along with pictures. First head I did (the one I'm running) I just got too wussy and didn't take enough material neither did a good job on blending the bowls. Well, better to take it appart and take another shot at it than junking a head as a debut, ain't it?

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.