How much do you think that I can get out of a non stroker, long rod combo (custom rods) big bore slant six?

specs as: cam in the 290° ballpark, revese dual pattern, (I know I need to study things a bit here) fully ported head with hearth shaped combustion chambers, 1.75 in 1.55 ex valves, thin stem (5/16) 10 to 11:1 static CR, 4 barrels reworked holley 4160 with annular boosters sitting on an offenhauser intake, headers with 2.25" dual tailpipes H balanced, MSD ignition, no power addersm no turbo nor neither juice or other gimmicks, bored to approximatedly 92mm piston diameter size?

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Juan Ignacio Caino

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All depends on head flow, component matching, and tuning. Somewhere between 200 and 300 HP at the crank. Knowing you, I would put the number somewhere around 260-290. What does "big bore" mean exactly?

Lou

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Home of Slant6-powered fun machines since 1988

92~93 mm piston bore size

redline around 6800~7000 rpm, geared to use amost full rpms range when usin it on the highway. If I can turn 6500 rpm at ~130 mph I'll be cool. (on 245/60/14's)

I think I have posted a photo of the head I'll be using. It was in a racecar, hearth shaped combustion chambers and really BIG port job, flowed to turn 10k rpm on a 170 crank and 92 mm bore size. (say 3 litres engine)

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Juan Ignacio Caino

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What rods are you using? 198 rods won't be happy for long at that RPM.

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Official Cookie and Mater Tormentor.

forged steel crank, billet custom rods (4340), floating pin, forged custom pistons, arp bolts on con rods, arp studs for main caps and head.

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Juan Ignacio Caino

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Sounds like a bullet proof bottom end.

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Official Cookie and Mater Tormentor.

Wow, that's a big bore. Stock bore size works out to 86.4 mm, and according to Doc, the walls are typically only 3.8 mm thick at their narrowest point. I'd be seriously worried about ring seal, unless you've got some trick up your sleeve, or rather, some trick sleeves in mind.

Or were the blocks cast in South America a bit thicker?

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

back in '79 local chrysler stepped up with the "906" slant six block (only produced in argentina), wich weights about 15 kilos more than a regular bare block, bore centers are corrected and spread a little bit and you can bore it up to .120 without sunnen machine or other expensive testing. I found a sunnen equipped shop and I'm willing to sleeve if needed.

906 blocks were fitted in cars and trucks at the very end of local chrysler production so racers could use it. There were a little more than 1000 blocks produced and there's still about a 1000 blocks in usable conditions, mine's in .020" (most of them are still in use, even having gone thru hard all out race seasons)

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Juan Ignacio Caino

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I'd like to know how much horsepower that 170 made on it's way to 10 grand.

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Franklin
'61 Valiant

This sounds like a serious pavement punishing engine there.Have fun beautiful work keep us posted i'm curious to see this beast running.

Kevin

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oh, this has been a long long project. Having one of these blocks with a matching racing head is kind of a responsability.

These motors when matched to the 170 crank and big bore, ended up in about 200 CI, with 320 peak horses, on old technology and fuel (20~30 years ago)

edit to add:

320 horses on class restrictions such as 9.5:1 compression ratio, limited to 2 barrels carburetion, well, you know about class restrictions...

Wich makes this project interesting (to me) is that 906 blocks are scarce, they are built to tolerate abuse over racing seasons (I thoght they had built them for industrial or heavy duty applications, but then I found and interviewed a guy who participated in the project) in fact, most of these blocks are still alive after 20 years of continued racing seasons (maybe new crank and guts, but the blocks are most appreciated because you don't find them just around the corner...)

So my goal would be a strong motor (I like 'zilla's "bulletproof bottom end" line), N/A, 4 barrels, good elastic cam with high rev potential and built to use and take advantage out of a 3.54 or 3.81 rear end ratio, close ratio 833, etc.

My only fear would be that the race head has too big a port for street application, but then again, I'll be boring this to have like 50 CI more than the original short block that they had in mind.

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Juan Ignacio Caino

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Cool, knowing some of the other things you've pulled off I was pretty sure you knew what you were doing with that huge overbore. I never knew about the 906 block, very interesting!

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

I think you will find that the long stroke of the Slant coupled with a stick will be very forgiving of the big port head on the street.

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Official Cookie and Mater Tormentor.

yes, plus this car would never see any "take the wife to the store" action again is gonna be my baby and I'm planning to mash on her hard. I like to take her out on road trips and I like to travel at night when cops sleeps!

I don't enjoy 1/4 mile track action so I'll be having a diet full of rice and small blocks, that's my plan

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Juan Ignacio Caino

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the only articles that I can think off are in spanish (regarding the 906 argentinian production heavy wall casting slant six block)

I'm a little bit affraid of building a monsterous bored slant, that's why I have been holding back so long. I had this block for free, but ain't like I'm likely to get another if I mess up. So I guess that I'll be doing it slow and easy, and take proper care of ultrasonic checking, and all the expensive tests (except for dyno wich I don' care much for, I prefer to fine tune by ear and seat of the pants feel)

I'm bound to do custom in/ex mani gaskets because of the size of the ports, plus intake manifold runners matching, and depending on compression numbers I would conider a blow thru... but I got to get the block bored and the short block bolted up together before I can come up with more "wild" ideas. I'd realy like to use the hearth shaped iron head because the guy who made it won several championships, he's a really good sl6 racing engines guru.

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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.