Thread: Dyno-Sim combinations

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Richard,
As usual, you have provided great information that is much appreciated. Thank you.

I was a little surprised to see the HP numbers that low, but very pleased to see the torque numbers in the rpm range you show. My goal was to build an engine with good torque and run on cheap gas and I think this will fit that goal. For a street driven car, I think I would be very happy with that kind of performance. In fact, now that I look at the numbers, I would guess the torque numbers are comparable to many of the 400+ hp engine builds out there, as they usually get their high hp numbers in the upper rpm range. At 420 ft lbs of torque, my car on the street should be very impessive. My other goal was to get good fuel mileage, but I don't think I will know for sure how that goes until I can actually drive it.

Squish/quench on the engine was calculated to be about .040 but I won't know for sure until Everything is assembled after the final decking and I do the final measurements. I have held off ordering a head gasket until after I determine the final "in the hole" measurements. So far I was planning for a .028 thick gasket to get the .040 quench, but we will see.

I also appreciate you doing a "what if" to show potential results with a few upgrades. I should be getting my block and heads back from the machine shop in the next couple days after the final decking ang milling, and I've already had the rotating assembly balanced and piston pressed on rods, so I will likely continue as previously specced, but I am having so much fun, that part of me wants to start on another build after this one and possibly go for a much more aggressive build, maybe something like a 383. We will see.

Overall, I have really learned a lot. Presently I'm getting ready to assemble the heads and am learning about, installed spring height, pressures and forces, and what causes valve float. It continues to be a great ride.

Originally Posted by rollie715

Richard, Thank you. I was a little surprised to see the HP numbers that low, but very pleased to see the torque numbers in the rpm range you show. My goal was to build an engine with good torque and run on cheap gas and I think this will fit that goal. For a street driven car, I think I would be very happy with that kind of performance.

You have to remember that the L31 heads have only a 170cc intake runner, so they're more of a torque head than they are a horsepower head. We could have made more horsepower with more SCR and more cam, but I sensed that you wanted an easy street-driver. Don't worry, it'll nail you back in the seat.

Be very, very careful checking the interface between the heads and the intake manifold to insure that they are parallel in both X and Y axes. If the port is gapped open at the top, you will have a vacuum leak that you can normally find with ether or other flammable spray, but if the port is gapped open on the bottom, the cylinders will be pulling oily vapors into the cylinder from the crankcase and you'll never find the leak with ether. I suggest sacrificing a set of intake gaskets on the mock-up build and closely inspecting them for being "pinched" all the way around each and every port. If not, further machine work will be necessary to make them parallel in X and Y.

on post #6 before i deck a block. i really know were the deck is that the part were building real engines you must know how your parts stack up

Originally Posted by pat mccarthy

on post #6 before i deck a block. i really know were the deck is that the part were building real engines you must know how your parts stack up

Pat, I assembled a rod and piston and measured all 4 corners before I sent the block back to the shop for final decking, so my design should be on track, but I would still like to confirm everything again as they are final assembled. I supplied the cut depths for each corner to the shop. The machinest is very experienced at building engines and squaring the deck to the crank.

Originally Posted by rollie715

Pat, I assembled a rod and piston and measured all 4 corners before I sent the block back to the shop for final decking, so my design should be on track, but I would still like to confirm everything again as they are final assembled.

yes and if your the guy doing the math and the guy decking the block then your odd.s could be better ?? that and the rods your using all 8 are the same over all distance . stroke is not off or CH of the pistons getting the deck true is more then a deck job the deck is the first thing that i will machine every thing is base off this less the block needs a line bore then thats first then deck then bored . the deck is the foundation of the block many time block will not clean up square up threw crank and cam center line were a tin shim gasket is going to work this get back to what CH the pistons you have