Block & Crank power handling

[ALLTRBO]

AaronGTR,
I'm not quite sure how that works either but I'll be reading up on it more, I'm sure there's a reasonably detailed explanation or theory somewhere around. I do know that it seems to be true though, because in addition to the article above I've known a few other people to build various engines with high rod/stroke ratios and they're running goodly amounts of boost on 93 compared to similar combos with stock r/s ratios.

1988GTU,
Not necessarily so. If you're staying near a given displacement with the rest of the specs identical then it doesn't matter much. While you'll be able to rev higher you won't really need to. The shorter stroke/longer rod engine might make more power up top, but in reality the powerbands will be relatively close.
For example: a stock 3100 is a 3135cc and the aforementioned .020 over 3400/2.8 is a 3063cc (close enough to each other).

Now if you take a 3400 (3350cc) and do nothing other than destroke it to make a 3063 (w/.020 over) then you'll have to rev it a similar amount higher to make a similar horsepower curve (3350/3063 = 1.094. 1.094 x 6000rpm = 6564rpm). The 3400 will have more torque and make it at a lower rpm, but the HP will be close between the two. This is all considering that everything else stays the same. That is: heads, cam, intake, exhaust, compression, etc.

Now, while increased RPM does stress a bottom end more, a shorter stroke and higher r/s ratio goes easier on a bottom end. I don't know if they balance out or if one stressor is more prominent than the other, but you have to take that into account.
As for the valvetrain, well, you're right there. The usual required mods apply for a given rise in RPM.
Aside from the valvetrain (which isn't much of an issue in this case), the 3063 will be more rev happy than the 3400.

[1988GTU]

You have to turn the rpm's up though! Everything gets stressed at that point.

[IsaacHayes]

Short stroke means the piston is not moving as fast, thus less heat.

[AaronGTR]

Ah, I see what you are getting at. The longer rod ratio affects the timing of the piston movement in the stroke and allows you to extract more power from the gas expansion. I understand how that gets you more power, but I never thought or had heard that that had any affect on detonation resistance. Interesting. I wonder how that works? Thanks for the link though, that's an interesting article. I should see if I can get my dad to build an engine like that for his '73 vette (has a stock 350).

[ALLTRBO]

...but detonation resistance is mainly piston and combustion chamber design and cooling.

...and combustion efficiency, of which the longer rod ratio improves on.

Here's a pretty cool, albeit older, article about a long rod SBC:

http://www.purplesagetradingpost.com/sumner/techinfo/350%20chevy%20engine.html

TGP code is limited to just under 14 psi and that may not be enough to reach the power level you've set. The code would have to be modified to get more boost out of it or you can trick the ECM but you loose tuning ability above the code limit. Code59 would be a better investment of your time and effort for 3 Bar MAP use.

Exactly, which is one of the reason's I'll be using $59 instead of $8F.
I didn't mean that I'm going to tune the car on TGP code, I meant that the car now has a TGP engine with a Gen III top end on it.
Thanks for the heads up though. As always, you know your stuff (I read a lot more often than I post, don't think I'm stalking you. ).

There is more to it than strength as I said before. It has lots to do with gobs of traction pushed by a tiny 5-speed transmission.
The Getrag 282 is to the T5 as the T5 is to the T56. I'm trying to see how far I can push it. To help that, I'm keeping displacement, compression, and centrifugal mass low, and boost (and turbo and W/A intercooler size) high. Shock loading kills manual trannies, not horsepower (to a point, but that point is way up there).
Beyond that, I get a higher rod/stroke ratio which is good for detonation resistance and will go great with a higher redline, I get the sexy sound of a screaming 60*, and also there's the added bonus of extra strength, which it may or may not need.

I have the entire setup worked out to support lots of shock-minimizing horsepower with all off-the-shelf parts, the only question was/is the strength of the stock 3400 block and stock 2.8 crank.

This is, of course, after the car is running and tuned with the TGP 3.1 and Gen III top end with lower boost (though, the same huge turbo setup), the 'preliminary' engine. That's making good progress as we type (since I had to farm out the work because my health issues slow me down too much).

Does that make more sense?

TGP code is limited to just under 14 psi and that may not be enough to reach the power level you've set. The code would have to be modified to get more boost out of it or you can trick the ECM but you loose tuning ability above the code limit. Code59 would be a better investment of your time and effort for 3 Bar MAP use.

[AaronGTR]

Where do you get that rod ratio has anything to do with detonation resistance? Sure it's got a lot to do with side loading on the piston and rpm capability... but detonation resistance is mainly piston and combustion chamber design and cooling.

[ALLTRBO]

There is more to it than strength as I said before. It has lots to do with gobs of traction pushed by a tiny 5-speed transmission.
The Getrag 282 is to the T5 as the T5 is to the T56. I'm trying to see how far I can push it. To help that, I'm keeping displacement, compression, and centrifugal mass low, and boost (and turbo and W/A intercooler size) high. Shock loading kills manual trannies, not horsepower (to a point, but that point is way up there).
Beyond that, I get a higher rod/stroke ratio which is good for detonation resistance and will go great with a higher redline, I get the sexy sound of a screaming 60*, and also there's the added bonus of extra strength, which it may or may not need.

I have the entire setup worked out to support lots of shock-minimizing horsepower with all off-the-shelf parts, the only question was/is the strength of the stock 3400 block and stock 2.8 crank.

This is, of course, after the car is running and tuned with the TGP 3.1 and Gen III top end with lower boost (though, the same huge turbo setup), the 'preliminary' engine. That's making good progress as we type (since I had to farm out the work because my health issues slow me down too much).

Does that make more sense?

[ForcedFirebird]

Have nice/safe trip betterthanyou!

Seeing we have a member here that is stretching the Gen1 mains only well after 400hp and 500ftlbs, I would gather that the Gen3 can hold quite a bit more power.

Also, you shouldn't worry about the nodular iron crank, they have been holding up quite well (post 1985 cranks that is). I am still not sold on the 2.8 crank for the stroke. Loner has seen spikes of 21psi and the ARP fasteners held fine on a 3400 bottom end

[geoffinbc]

I do believe I have 3/8" 3400 flanges here. In fact they are the last set. But since I leave at 4 in the morning tomorrow you will have to wait 2 weeks until I can ship them.

They are $50 shipped.

[ALLTRBO]

Okay, thanks.
Darn, I should have found out about you sooner. I guess I'll just have him go ahead with the headers with the mild 3/8" flanges from WOT-Tech since he's going to start them next week.
Have a good trip!

[geoffinbc]

Yes I can have the flanges made but I am leaving for Mexico tomorrow morning for 2 weeks so I wont know how long until I get back.

[34blazer]

too bad you cant use the old buick 231 rods, they are strong to 800+ hp when prepped correctly

[ALLTRBO]

I've read that also about the 4.3 rods, but just as importantly they aren't available in 5.85" like SBC rods are and that throws off my whole plan.

Can you make the SS flanges in 1/2" thick? How long would they take to make?

[farmerz24]

I can still get the SS Flanges if you want them. I do not have any on me they would have to be made.

You could probably work over a set of 4.3L Chevy rods in order to fit the 3500 Crank. But I agree you need to weigh the cost versus the benefit.

i was going this route. the 4.3 rod big end is offset. which means there is more meat on one side of the big end than the other. unfortunately, this was only noticed once the rods were bought. i havent looked to see if i can shave off the longer side and still be OK!. im hoping so but i dont have the big end width measurements. maybe ill measure tonight.