[parish8]

https://www.tfxengine.com/SuperchargedEngineData.html

I am not familiar with all the options but that page makes it look pretty cool.

[gtfoxy]

Originally Posted by parish8

Whoa, I was thinking in more simple terms. Make a run at let’s say 20psi of boost and 18deg of timing. Record peek cylinder pressure. Now pill timing and add boost to get back to that peek number and see what happens to hp. If it goes up pull more timing and add more boost.... that type of thing. All the while keeping an eye on egt’s, exhaust back pressure... try different fuels and different iat’s.

Is cylinder pressure even the limiting factor for one of these engines?

That’s pretty much what I thought you were getting at.

Ignition advance & exhaust pressure all correlate to pumping losses.

Inevitably there will be a sweet spot relating to charge density.

[parish8]

Originally Posted by gtfoxy

That’s pretty much what I thought you were getting at.

Ignition advance & exhaust pressure all correlate to pumping losses.

Inevitably there will be a sweet spot relating to charge density.

I was thinking it would be more of a crank angle and rod angle combined with timing of the cylinder pressure while watching for unintended side effects.

In my case I have a lot of turbo available, I have a lot of fuel system available, I don’t care about efficiency or emissions. My only concern is what gets me the most power before reaching the limit of a given set of parts.

To me this type of stuff is the fun part. I enjoy building and learning and sharing more than the actual car once it is running.

[gtfoxy]

Originally Posted by parish8

I was thinking it would be more of a crank angle and rod angle combined with timing of the cylinder pressure while watching for unintended side effects.

In my case I have a lot of turbo available, I have a lot of fuel system available, I don’t care about efficiency or emissions. My only concern is what gets me the most power before reaching the limit of a given set of parts.

To me this type of stuff is the fun part. I enjoy building and learning and sharing more than the actual car once it is running.

Exactly.

Stroke & rod/ ratio determine piston acceleration & deceleration at a given RPM. There’s a metric ton that goes into it that, quite frankly, is limitedly controllable. The reality is quite start when you realize matching flame propagation rates to piston acceleration rates where real energy conversion occurrs is well north of 15k RPM.

Energy conversion is a fickle beast, & that’s what you are after. Most energy output at a given energy content in the chamber. As I’m sure you know though, 3kpsi of cylinder pressure at TDC is not the same thing as 3Kpsi at 20ATDC in simple terms of present volume.

Oh, & TFX has been around quite a while. Good stuff.

[parish8]

“Most energy output at a given energy content in the chamber. “

I am not looking for this. Unless this is what also results in my actual goal.

What is the limiting factor on the motor I am building? Cylinder head sealing? The block? The rods? The pistons? The crank? The mains?

If it is cylinder head sealing or the pistons/rods I think setting a hard limit on cylinder pressure and tuning for max power while staying under that limit might result in a motor that makes a large amount of power and stays alive.

Currently my timing is in the 16-20deg range depending on rpm and that is backed up by the dyno and what most other people seem to run. I see nice gains going from 16-18 and much smaller gains above that. What should that timing look like at 30psi? How about 40psi? Just using the add timing as long as there are good gains might not put you at the same spot at looking at cylinder pressure and keeping it under a certain number.

[gtfoxy]

Originally Posted by parish8

“Most energy output at a given energy content in the chamber. “

I am not looking for this. Unless this is what also results in my actual goal.

What is the limiting factor on the motor I am building? Cylinder head sealing? The block? The rods? The pistons? The crank? The mains?

If it is cylinder head sealing or the pistons/rods I think setting a hard limit on cylinder pressure and tuning for max power while staying under that limit might result in a motor that makes a large amount of power and stays alive.

Currently my timing is in the 16-20deg range depending on rpm and that is backed up by the dyno and what most other people seem to run. I see nice gains going from 16-18 and much smaller gains above that. What should that timing look like at 30psi? How about 40psi? Just using the add timing as long as there are good gains might not put you at the same spot at looking at cylinder pressure and keeping it under a certain number.

It sounds to me that’s what you’re after.

Others are much more experienced in knowing where your practical limit is with that engine than I, but I’d say “all of that” LOL.

There’s going to be a point where “optimal” timing isn’t going to be the main focus. It’s going to be what point in the whole combination (fueling, injector timing, ignition timing, charge density, chamber pressure curve, valve curtain, etc) you 1: reach a power point you are happy with or 2: it goes boom. You already knew that I’m sure.

I’m just excited to see where you end up.

[ZO6Ted]

Originally Posted by parish8

“Most energy output at a given energy content in the chamber. “

I am not looking for this. Unless this is what also results in my actual goal.

What is the limiting factor on the motor I am building? Cylinder head sealing? The block? The rods? The pistons? The crank? The mains?

If it is cylinder head sealing or the pistons/rods I think setting a hard limit on cylinder pressure and tuning for max power while staying under that limit might result in a motor that makes a large amount of power and stays alive.

Currently my timing is in the 16-20deg range depending on rpm and that is backed up by the dyno and what most other people seem to run. I see nice gains going from 16-18 and much smaller gains above that. What should that timing look like at 30psi? How about 40psi? Just using the add timing as long as there are good gains might not put you at the same spot at looking at cylinder pressure and keeping it under a certain number.

Very interested in this also. A mid 9 sec 5.3 approx 4700 race weight I think was at 11 deg timing. As in other post sbe 5.3. BTW been following you since the old Honda bike vs turbo Silverado vid days. You're an icon. I'm new here but not new.

[parish8]

Originally Posted by ZO6Ted

Very interested in this also. A mid 9 sec 5.3 approx 4700 race weight I think was at 11 deg timing. As in other post sbe 5.3. BTW been following you since the old Honda bike vs turbo Silverado vid days. You're an icon. I'm new here but not new.

Thanks. I just got into the turbo stuff before it was really popular. It is crazy how fast people are going these days.

Your saying you have ran mid 9’s at 4700lbs. How fast? What kind of 60’? How much boost? Just 11deg huh? Is that typical for the sbe crowd? I would like more info on this type of stuff.

[ZO6Ted]

Originally Posted by parish8

Thanks. I just got into the turbo stuff before it was really popular. It is crazy how fast people are going these days.

Your saying you have ran mid 9’s at 4700lbs. How fast? What kind of 60’? How much boost? Just 11deg huh? Is that typical for the sbe crowd? I would like more info on this type of stuff.

No not me I wish lol! Not typical but doable as there are a few. He's had this truck since before my turbo truck in 07. Race weight is guesstimate with driver and gear. 9.47@141 mph not sure on the 60 but low 1.4x. 21lbs. Says he gapped the rings, changed cam, springs, studs and lots of tuning, shock relocation etc. He goes by fastjweb on my home site performancetrucks.net. Time is in his sig. We talked about me buying his 2wd truck in Feb. I didn't want to just lay rubber at 80 with a light rear end so I decided on my 4wd build instead. Didn't realize how much I'd be spending on fueling. I thought last nite, it is LS 5.3 though (hence the timing w/o DI) unlike the other dyno post earlier an LT 5.3.

[parish8]

Hmm. Pretty happy with that et. This is the last trip to the track before it gets upgraded.

100% stock 5.3 with dod, vvt, stock springs.

13.5psi, 4000rpm launch at 8psi. 5900rpm shift points.

[laynlo15]

That is a great pass for what little you have done and a pretty much bone stock 5.3. Congrats. Thats a high 9 second quarter.

[gtfoxy]

Originally Posted by parish8

Hmm. Pretty happy with that et. This is the last trip to the track before it gets upgraded.

100% stock 5.3 with dod, vvt, stock springs.

13.5psi, 4000rpm launch at 8psi. 5900rpm shift points.

What were doing for a cam?

Add: I’d love to see the card.

[KingLT1]

Nice pass!

[parish8]

Here is a little data. I need to recheck my exhaust pressure sensor. Seems to good to be true.