HabanaJoe

29Firefox-

That is interesting, they milled off the casting, wow ahead of our time by 15 years!!

I see basis "D" shaped exhaust port, thank you BIg Block Chevy!!!

What do you do that you know about the 7100 series pumps? I guess bigger plunger/barrel sets are available now? That is a great pump, very small in size.

TopSpin80

a few pictures of the most interesting I have found.

Ernie

Michael1

I guess it depends on what your goal is. If you don't care about having a dirty engine, or one that has poor fuel economy, then by all means ignore chamber turbulence.

Michael

TopSpin80

a few more

HabanaJoe

michael,

I agree with you they serve a purpose but you can't get enough air in there to make 500-700 hp like the question was.

I also agree that at low speeds it will hurt engine because that swirl helps create velocity and at low rpm with no boost the engine won't breath that well. It like putting bigger valves in a gas engine, they loose the low rpm's of the power band.

TopSpin80,

Look at those exhaust manifolds, 1,2,3 & 4,5,6 tied together. I also see on the one head they milled off the cast intake which is exactly what the Banks head looked like. You can't get into all the ports as well as you might want to without doing that.

But, you can get in and do lots of work on the ramps without cutting off the cast in manifold.

Let's see where this goes.

mthill

First post, but I've been lurking for a long time. This is a good thread with lots of info. I have to put my $.01 in as well.

Removing the swirl ramps in the Cummins head results in very large gains in flow for high hp applications. Milling of the "manifold" doesn't do a lot on its own, but it does allow you to do additional porting to pick up some more flow. Maybe 75% of the gains to be had are from removing the material that shrouds the valves (and you can get to it easily with the valves out). A new manifold can also improve cylinder to cylinder distribution, if the manifold is done right.

I agree with Joe about combining 1,2,3 and 4,5,6. It's been done before and it works. I saw it on a 700hp marinized ISB, with one turbo on each manifold. They were parallel twins. I wouldn't recommend that level of output on a stock block for long term usage at rated speed. The block can fail at the top of the cylinder where it joins the firedeck...possibly a thermal fatigue issue due to locally poor coolant flow. If it's for short bursts to rated speed with mostly cruising, it's probably not a problem.

I'm not sure I agree than a header style exhaust will make a LOT more power. I've got no argument against it being better, but can't really say how much. Picking up a bit of boost only helps if you've got fuel to burn (ie smoke) and there are probably easier ways to pick up boost. It's certainly not cheap to build water jacketed header style exhaust.

I'd pass on the VG turbo in favor of less complicated solution. Joe's idea about switching between one and two is a good one. It's in current production engines from MTU as well, switching between one and three. With a manual valve you'd have to be careful to not accidentally over-speed when running on one. Having the computer do it for you would be a much better option.

There are better pistons available off-the-shelf. Mahle is selling a Monotherm steel piston that will work well and is very durable. You will not break one. Period. I think they're a few hundred $ per cylinder with a ring set. The stock pistons may work...for awhile. I'm not sure how a Cummins Marine piston differs from the pickup truck version (bowl shape maybe).

I'm afraid none of this truly addresses the original question of how to do it in the cheapest possible way. The cheap way will probably be a nightmare in real life and end up costing you more than you expect in the long run. So, buy a used marine engine. Doing it yourself, the right way, will cost more.

29Firefox

It's more than pumps & plungers.The pump dude gets in there and messes with the rack & governor and the cam looks different. They won't tell me exactly what they do. The only problem I've had with the modified pumps is indexing.

29Firefox

Making a totally different exhaust manifold would work real good. But theres that red neck step that will get you in that direction without major cost. The stock configuration of a turbo at the end of a log manifold sucks. If you put temp sensors in each manifold port you will get 6 different temps. #1 being the lowest and each temp climbing with #6 being the highest. Now the stock QSB exhaust manifold has a hold over from the 6BT. Some of the 6BT engines were used to power gensets. To move the turbo and exhaust away from the genset back end they designed a second outlet in the middle on the top of the marine manifold. To reduce cost they designed the stock manifold to be used in either configuration. The gen set outlet is on top right between 3 &4. By changing the outlet port the stock manifold mimics a 123&456 header. It's not as good as a purpose built header but it costs a lot less.

29Firefox

Past 550 hp on the QSB you start having problems with the lift pump and fuel filters starving the pressure pump. Easy fix bigger lift pump (Holley) and bigger filters (Racor). Don't forget that you have to filter down to 2 microns for the common rail injectors to survive. Past 600 hp injector flow isn't up to snuff. Have the tips extrude honed.Then some where between 750 hp and 800 hp the pressure pump can't keep up. Heard some people have gotten past that by adding an extra belt driven pressure pump plumbed parallel to the stock one. Ain't seen one in person yet.

29Firefox

I love steel pistons. Stronger and better piston to bore clearances across the temp range.