thank you for the reminder...250ish hydraulic roller.
I have the build printed out..

https://www.motortrend.com/how-to/hp...parts-lsx-454/

 

Good points,I'll try to get the dyno sheet today. Also, maybe something up with the valve springs?

So granted I don't know everything about LS's but the sheet I saw the car stopped increased at 6k, but some might say it was even earlier. So I'm thinking since he ordered the NW 102, will make a 4" air intake, maybe at the same time he can report what springs he is running too? It made 488 on the portable Redline Performance Dyno at LS Fest. I don't see this car hitting 550rwhp unless there is a big spring issue?

 

If it were mine I would do basic maintenance before replacing parts, no reason his existing parts shouldn't be making more power. I would check for spark, check plugs, check springs, do a compression and leak down, etc before throwing parts at it.

Stock LS7's make about 450whp, he's not much above that and there has to be a reason. Is the converter performing as it should?

 

Converter is a single disk PTC. He's been told by them not to lock it up, I suggested going to a lock up version because I think he's driving through the converter. That reminds me, so he did 488rwhp unlocked, usually we'd see a good gain from locking the converter, 20+ rwhp from locking it would not be out of line right? That would put him more like at 510rwhp. If he can do that some day, and swap the TB and air intake, tweak the tune a little, maybe he starts to get to 530rwhp or more? I really want him to figure out the compression, because if it's on the upper end I think he'd benefit from flex E85. I've seen a buddy pick up 40rwhp with a 12.2:1 427 ls stroker.

 

Peaking early and a boat load a torque really sounds like cam timing, like an install error.

 

 

First of all I wanna say thanks to all who have responded. I ordered the NW 103 yesterday. Trying to figure out what to do about the air intake. not sure the 4" is gonna do the job.

 

Whoa momma, that's ugly. It looks like a dynograph from an old peanut port big block. The way that torque takes a nose dive so early, I would think either the valvetrain was set up my Helen Keller or the throttle isn't opening all the way.

 

Where are you located?

 

Chicago.

psicko, did you have a suggestion?

 

Do you know stall speed of the converter?

Is it possible to dyno with it locked?

Very strange graph. Any chance it spun the tires on the dyno?

Does anyone have software to datalog this thing at WOT on the street on a longer pull from like ~3000 rpm to redline? Third gear pull would be ideal.

The induction mods are only going to help, but I'm not convinced there isn't something odd going on.

 

That engine is being strangled above 4K rpm. Seems like a cut and dry case of the basic prerequisites of air, fuel & spark not being met. There might be other issues with engine combo like cam install and intake runner length, but put all that all aside and stop thinking about it until you take care of the basics.

4" throttle body is a good move. You're probably going to need a 5" air tube feeding it. I also have an old car with filter located in an empty battery tray. Guys like us use long sections of uniform diameter tube and conical air filters, and it doesn't work as good as a lot of people think. Look under the hood of a modern car and you'll see a HUGE inlet that is tapered toward the throttle body. Our little 4" tubes are way more restrictive than that. I started off with a 4" tube and ended with a 5" tube and smooth reducer elbow at throttle body. The 4" tube was really good up to about 500 RWHP and then it started pulling a vacuum. I also have a big *** air filter because the useful flow area of a conical air filter is not as much as it seems. All that stuff can be figured out looking at MAP values at WOT.

The other problem I had was lack of fuel and you might be experiencing the same. AFR readings were fine and injectors were at 70% duty cycle. Huh? Lack of fuel? Yeah, big time. Spark plugs were reading lean and spark plugs don't lie. Installed a fuel pressure sensor and could see fuel pressure drop to ~52 psi at WOT, and a little volcano was forming in the fuel map (Holley EFI) because the ECM was trying to dump in more fuel to compensate for the pressure loss. Again, AFR was hitting target so ECM was happy but the spark plugs told the real story. Upsized my fuel pump and the engine drank +25% more fuel, and that my friend was a whole lot of power. I share this story because lack of fuel can be a little hard to diagnose if you only look at AFR.

Seems like you have enough exhaust for now. It's not optimal but it's also not a huge contributor to your problem.

You also might have the cam installed too far advanced by accident. I did that once and engine HP peaked at 5500 rpm and just table topped out to 7K rpm because the top end could still support the air flow.

Basically I've done a lot of things wrong and it looked a lot like what you've got going on. But I figured it out and you will too.

 

@Project GatTagO , maybe you can share some more info?

I heard in conversation the cam was installed a little advanced.

 

Power does begin to flatline around 4000 rpm, and you can even lay a ruler on the torque curve from 4K - 6.5K rpm. That's not a natural torque curve. That torque curve is telling you loud and clear that the air flow rate is pretty much constant no matter how fast the engine spins above 4K rpm.

 

A stock ls3 TB will move over 1000cfms and so will a 4 inch tube.
https://accufabracing.com/cfm-air-flow
A 460 c.i. at 7000rpms needs around 940cfms....assuming 100% VE.

 

Your torque curve is unnatural because there's a fundamental problem with the rest of the car being able to deliver air, fuel, spark to the engine. One or more of those things aren't up to task. There might be other issues with engine layered on top of that but it's going to be hard to troubleshoot until the basics are fixed first. Once you get the basics figured out then you'll be able to see the natural torque curve of the engine and what it can do. And then you can decide if you want to make changes to the engine itself or leave alone.

Air intake is obviously a pinch point, it's something that will need to be addressed no matter what. Your efforts are not wasted in that department.

It would be useful to now share more details of how you set up fuel delivery (pump, plumbing, wiring). There might be work to do in that department too.

 

Single intank Walbro or something right? What size injectors. Car is wired up with a Holley Terminator.

 

A
You can't take all flow #'s at face value. You can change the flow # in any direction just by playing with the depression when it's flowed. Just for refernce, I have seen 440/454's pick up going to a 108/112 TB, have even seen gains on top of that w/ dual throttle bodies. Just depends, every combo is different.

 

When the car gets to 6000 RPM does it slightly break up or stay smooth?

 

Im not saying it won't gain power with intake upgrades. I'm saying that's not the root of the issue and why it won't rev to 7k. A stock LS picks up with larger intake upgrades so of course a 460 will.