I don't buy the 4 main being weak story. I have seen a lot of Slants really wicked up and very seldom see the block or crank break. The few cranks I have seen blown out were the result of hydrauliced cylinders, and 7 mains won't live through a full wet cylinder either.

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Official Cookie and Mater Tormentor.

I won't go over 5500 rpm. But you think it will withstand the boost? 35 psi is a lot of added compression.

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Boosted? Only slightly.

You need to find out what Cameron Tilley is doing to have 600+ HP. and study that.

I know Will has had some growing pains with his "World's fastest Slant 6" but it hasn't been crank problems. I am not sure how much boost he is running either.

I venture to say that you may have cylinder head sealing problems before Crank problems at 35# boost.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

35# of pressure is a good bit, but that's only ~7# more than some run.

1. I agree with Rick, and predict cylinder head sealing will be the first roadblock you run into

2. You better do something radically different if the motors running 28# are only making ~550 horse, and you expect to reach 800 with only 35#. If you're relying on shear poundage to get you there, it's gonna take a lot more than that.

3. Again, I'm gonna agree with Rick. Find out what it takes to make >600. I hear they don't have anything more than good f/i practices. That being said, 'good f/i practices' is more than reading one book

4. If the Buick guys can get these numbers, I don't see why we can't get at least close. The problem is, those that are above 700 horse with the Buicks are EXTREMELY built. And they have a 20 year headstart by coming from the factory with a hairdryer strapped to 'em.

5. I think you are worried about the wrong things. I haven't heard you mention anything about your plans for a head yet. I'd say head will be the most vital part of your goal.

My unasked for $.02

You will blow the head off or melt pistons long before you blow the crank out. The 4 bolts per cylinder is kind of like a circuit breaker.

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Official Cookie and Mater Tormentor.

I'm already taking care of the head and sealing.

ARP 220,000 psi studs
Copper head gasket
O-ringed block
Forged Ross Pistons
Gapless rings
XHD wrist pins
Molnar forged rods

Don't worry about the rest... No shortcuts are being taken.

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Boosted? Only slightly.

I am pretty sure Will Burns was at 15 psi for his runs. Tilley used about 20 psi for 630 HP (@ around 5100 RPM), but said there was not a lot of HP gain from 18 to 22 psi with this setup. I believe he has only broken cranks on his hi rev NA motors (~350 HP), and never on the turbo motor.

Lou

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Home of Slant6-powered fun machines since 1988

Well I'm pretty sure I'll see a difference at 30 pounds. So I should be fine with the forged crank is what I gathered. I'll just run 4140 mains and try to figure out a girdle.

The biggest issue the slant has in power restriction is the head.. Obviously I'll do some porting and valve work. It needs a good set of rockers, possibly rollers, to keep each cylinder's A/F ratio equal and be a good driver as well.

There's a lot of new tricks out to get that turbo to do extra work per pound, so I'm probably going to be doing a lot of little things to my motor. Hopefully it will all add up to one, big, mean, boosted, leaning tower of power.

You guys should look into ceramic coating. They've started coating combustion chambers to prevent heat exchange and in return further increase exhaust pressure. Also, the longer the turbo header the better in my application. Sure, slower spool time... but in return you get high compression ratios with less chance of detonation due to less exhaust getting back into the cylinder.

I'm also going to be looking into air cooling... I know I can simply innercool it, but there's water to air coolers as well that do an even better job. I've got a book on little tricks for turbos, so everything I find useful will be put into my plan. Possibly even having oil jets spray cool oil on the bottom of pistons to further prevent detonation... It'll be a lengthy, detailed build, but that's the fun part!

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Boosted? Only slightly.

Tilley's crank issues were really Fluidamper issues. He switched brands and his crank issues went away.

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Official Cookie and Mater Tormentor.

I think I'm going to pick up a SFI rated damper from 440 source

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Boosted? Only slightly.

Mike Jeffrey swears by ATI dampers. They have made custom optimized ones for the 225 engine.

Your comment about the head is relevant. If you want to spend time and effort and money, do it there, not the crank.

I was not suggesting you can't see a difference above 20 psi, just that someone has made 630 HP at fairly low RPM with only 20 psi. I'm very interested to see the outcomes of your experiments!

Happy building,

Lou

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Home of Slant6-powered fun machines since 1988

Interesting turbo build. How is it coming together?

About the fuel are you going with Sequential fuel injection and secuential ignition? if you are you should check FUELTECH FT500 ECU from Brazil. They have a representative in the US, I think that the Proline people are.
check it at www.fueltech.net

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

I'm currently trying to track down a Billet crank. At this point I'm getting quotes for a custom crank. I know people mentioned not to worry about the crank, but I'd rather know the crank and mains aren't a weak point and overkill than have them scatter at 25+ psi.
I've actually got fuel injection and ignition figured out. I'm going with FAST injection dual port injection. Two injectors per port. One running pump gas and the other set up on a boost control module to come on at a certain psi with 116 octane.
Having major porting done to the head and some nice pretty custom stainless valves. Head sealing is going to be the most important. The head has been grooved for o-rings and I'll have a nice thick copper gasket made for it.

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Boosted? Only slightly.

Sounds like a great project. We are all interested to see how it turns out.

Hopefully you can bring it to a Slant 6 drag race at some point. Even if you don't want to run it, our racer community can see it up close!

I live in Virginia, but will make at least one Slant 6 race our West next year, likely in CA, since my car is now living in Seattle for a while with a good friend.

Happy building,

Lou

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Home of Slant6-powered fun machines since 1988

I recently moved to alabama! So I'm a lot closer to all the slant guys.

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Boosted? Only slightly.