[WiggyB]

Question for those looking to run or already running port injection on your vehicles. Being that adding port allows you the ability to shift at higher RPMs have you changed your shift points? I normally shift between 65-6700RPM where max boost is hit and continue to do so. I don't see the need to redline it especially since still on the stock long block.

Thoughts?

[radz28]

I didn't change my shift points. I'm running a slightly smaller upper for a couple more pounds, and am positive power doesn't peak (boost doesn't drop-off at all at redline and above), but I don't see a need to push the valves open on OEM springs, so I leave it to shift about redline. I could be wrong on that, but I know of a couple people running about the same boost, on LT4s, moving toward 7000, so, for now, I'm leaving it there. I'll swap springs when I replace the lifters in the future, and rethink it then. I don't have traction anyways, so there's no point in beating the car up, lol.

[18.2SS.1LE]

WiggyB, your boost should continue to climb the higher you rev it with a Procharger. I usually shift around 7,100 but I have a cam. If you were to bump yours up a couple hundred RPM, you'd be starting with more power in the next gear as well. Not sure how strong these stock valve springs are, especially with boost though...

[WiggyB]

Originally Posted by radz28

I didn't change my shift points. I'm running a slightly smaller upper for a couple more pounds, and am positive power doesn't peak (boost doesn't drop-off at all at redline and above), but I don't see a need to push the valves open on OEM springs, so I leave it to shift about redline. I could be wrong on that, but I know of a couple people running about the same boost, on LT4s, moving toward 7000, so, for now, I'm leaving it there. I'll swap springs when I replace the lifters in the future, and rethink it then. I don't have traction anyways, so there's no point in beating the car up, lol.

I have to agree with you there. Since completing the build I find myself driving the car more and enjoying every minute. Previously I was shifting lower than now around 58-62000rpm. So in a way I did change my SP but was wondering if it would benefit at a higher range.

[WiggyB]

Originally Posted by 18.2SS.1LE

WiggyB, your boost should continue to climb the higher you rev it with a Procharger. I usually shift around 7,100 but I have a cam. If you were to bump yours up a couple hundred RPM, you'd be starting with more power in the next gear as well. Not sure how strong these stock valve springs are, especially with boost though...

I was thinking that as far as boost power but I don't want to push it too far. I'm in a pretty good sweet spot right now though.

[Joshinator99]

Originally Posted by WiggyB

Question for those looking to run or already running port injection on your vehicles. Being that adding port allows you the ability to shift at higher RPMs have you changed your shift points? I normally shift between 65-6700RPM where max boost is hit and continue to do so. I don't see the need to redline it especially since still on the stock long block.

Thoughts?

Port injection has nothing to do with the RPM capability of the engine…your stock valve springs are not going to tolerate any significant increase in engine RPM. If you want to spin harder, the valve train needs some work.

[WiggyB]

Originally Posted by Joshinator99

Port injection has nothing to do with the RPM capability of the engine…your stock valve springs are not going to tolerate any significant increase in engine RPM. If you want to spin harder, the valve train needs some work.

Correct me if I'm wrong but my understanding that port allows fuel in the chamber for a longer cycle than direct injection. In returns allows you to rev the engine slightly higher. So with that addition you could stretch it out a little further.

[Joshinator99]

Originally Posted by WiggyB

Correct me if I'm wrong but my understanding that port allows fuel in the chamber for a longer cycle than direct injection. In returns allows you to rev the engine slightly higher. So with that addition you could stretch it out a little further.

Either you have the fuel to support the airflow at the given engine load…or you don’t. You can accomplish the same thing with correctly sized DI fueling. Yes, port can spray over a longer injection window…but that doesn’t mean higher mechanical engine RPM capability. I can rev higher than you even though I’m DI only…because my valve train is setup for it (and have the fueling to support it…barely lol).

You shouldn’t push the RPM much higher until you upgrade the valve train. And even then, you’ll want to data log where you shift, where you end up after the shift, and residence time in each RPM range. Then you can maximize your acceleration by fine tuning your shift points.

[Megahurtz]

^^ Listen to Joshinator99. He is correct. Don't push the stock LT1 valve train past 6700. It won't survive long at your power level and you'll be rebuilding the engine.

[WiggyB]

Originally Posted by Joshinator99

Either you have the fuel to support the airflow at the given engine load…or you don’t. You can accomplish the same thing with correctly sized DI fueling. Yes, port can spray over a longer injection window…but that doesn’t mean higher mechanical engine RPM capability. I can rev higher than you even though I’m DI only…because my valve train is setup for it (and have the fueling to support it…barely lol).

You shouldn’t push the RPM much higher until you upgrade the valve train. And even then, you’ll want to data log where you shift, where you end up after the shift, and residence time in each RPM range. Then you can maximize your acceleration by fine tuning your shift points.

Understood and makes total sense.

[WiggyB]

Originally Posted by Megahurtz

^^ Listen to Joshinator99. He is correct. Don't push the stock LT1 valve train past 6700. It won't survive long at your power level and you'll be rebuilding the engine.

Trust me I'm not doing anything crazy. I probably on get in that range 2 or 3 times a month and that's just to make sure the meth pump and PI gets some work. I'm just enjoying the car right now. Got a 402 bb that needs my attention now so I need to find something to put it in. This new stuff is out of my league need to get back to my roots. LoL