UPDATE: Took the car back to the same dyno with hot tires and strapped the crap out of it. It took a couple pulls for it to hook. I added a little to much fuel to the last pass up top but here are the results:



So I built a guy a LSX 454 for his 06' Z06 after the exhaust valve decided to vacate the motor out of the side of the block. The first graph is over MPH and shows the problem. The second graph is another Z06 I am doing with H/C to really show the problem. I tuned both of them less than 30 minutes apart. I expected the 454 to make 620/560rw. The thing makes 460rwtq at the hit and doesn't get any better till the end of the run which makes no sense to me. I designed the motor not to exceed 6,500 rpm since the SS intake valves and springs coupled with the FAST just won't allow power to be made much above that on this size motor. Just for perspective, a 15' Z06 with full exhaust, pullies, CAI and tune only put down 630rw on this dyno. I think he said 15lbs of boost but don't quote me. Runs started at 2,750 and ended at 6,750.

Does this look like clutch slip, spinning on the dyno, something in the drive train? The 454 was run second and there is nothing in the logs to indicate anything is wrong at the motor. KPA is good 101-98, DynCyl follows on both although the 454 only peaks at 1.11 like the 427 but doesn't drop off like the 427. The 427 ends at .94 at 6,800. I am not sure if an exhaust restriction would show in the logs though. I am not sure where to go with this. Any suggestions would be greatly appreciated.

454 mod list: 600 miles on motor
TEA/TFS 260 heads
BTR STG IV cam 246/254 111
8.75 DCR
Lunati lifters - 3/8" push rods .0030" preload
Haltech 108
Ported FAST 102 and NW tb
OBX 1 7/8" catted LT's with stock cat back
60lb injectors
Monster LT1 Twin

427 mod list:
FRH ported LS7 heads
bullet 242/248 114
8.5 DCR
3/8" push rods
Vararam
Ported FAST 102 and NW TB
TSP 1 7/8" headers with stock cat back
stock injectors
McLeod RXT Twin

 

That is weird. I would have expected more torque as well... especially with the TFS 260s and the 454.

 

I just don't see how a N/A motor makes the same tq at 2,600 that it does at 5,000. Thay all gain atleast 50rw minimum.

 

That's not all that weird with the rectangle port stuff. They don't "come on" the same as the cathedrals and have a flatter torque curve typically. But the curve should be higher.

Hell, Brian Tooley had a 416 with stock LS3 heads do 600/560 on an engine dyno... which translates into something close to 530/490 on a dynojet.

 

We just back to back tested a pair of AI CNC LS7 heads against the TFS 260's and the AI heads made 20 rwhp more power. It was our LS7 Stg III cam and the car went from 580 rwhp to 600 rwhp.

With that said, I think the bearings on the dyno need greased or something, it doesn't look right.

 

Those graphs make my head hurt. Turn them both the same way. And why don't you have one of HP vs RPM? Not sure how the speed graph shows the "problem"? It's also weird that they made within 2 hundredths of the same torque number.

 

That's somewhat surprising. The TFS 260s don't look that great. I've seen a few results now and they aren't overwhelming. And just to digress - the 255s seem to be doing well though? Have you back-to-back tested them against anything from AI or MAST? That'd be the test against MAST...

 

Brian, the car that was tested.... was it a Vette or a F-body?

 

It is the way the graphs loaded on here for some reason. I tried messing with it but it didn't change. The dyno owner laid it over MPH to see if it changed the graph in anyway. We were also trying to see if the mph would show clutch slip or tire spin. The problem being that it makes peak tq at 6K and only makes 10 more than at 2,700. The MPH graph is the one I accidently printed since it was up. The only RPM graph I have is the one comparing the two cars. Hence the reason both are on there. Just look at the second one if the first one hurts your eyes. I don't think anyone on here has seen a tq curve look like this.

 

I was hoping you would chime in. I was going to call you but haven't had a spare moment. I am guessing that the 260's are just to small. I was trying to maximize tq and the curve below 6,500 on this engine. That is why I went with the STG IV and not one of my larger custom grinds also. I still don't see how there is no curve to the tq curve. Something must have been up with the dyno. I am working on a couple sets of LS7 heads right now with really good results. One is going on the second car in this thread if the current heads don't work out and another is going on a different 454 I am doing. Would pulling the 260's and porting them be worth it? I can open them up some on the intake and improve on the exhaust. What do you think a 2" header and no cats would be worth?

 

I would have a close look at the valve train, especially the lifters.

I recall a motor with a similar problem last year and it ended up being the lifters that were preventing the motor from making power and having a weird power curve.
They swapped in another brand and the thing ran strong

 

I had considered that as well since I used the Lunati link bar lifters for the first time. The preload is so minimal and has to be super precise. I remember having to order custom length pushrods since every time and way I measured them they came up shorter than they should. A .040" window of preload sounds like alot until you consider that pushrods only come in .025" increment and you can't adjust your base measurement. I was right in between IIRC. I really hope it isn't lifters. Those things were quadruple the price of LS7 lifters. That and being a huge PITA to get to.

 

I agree with a lifter issue or a cam timing issue. Those lifters are only preloaded .003"? The torque peak is way late. Like the cam is retarded.

 

I had some 260's on my supercharged C6 Z06 and it made less power than a car almost identical to mine with stock LS7 heads, except it had a smaller cam. However my shortblock wasn't healthy so it was apples and oranges.

I did build a new shortblock, changed to the smaller cam that made more power, hand ported the heads, changed the boost juice to M1, gutted the cats and it picked up 130 rwhp and 110 rwtq, so who knows...

I brought the short turn height down to be like stock LS7, rounded it over, deshrouded the chamber with a 1/2 round burr like I normally do.
It looks like they were trying to get high lift airflow by leaving the chamber shrouded, and trying to get mid lift airflow by leaving the short turn tall and square, which is the opposite of how I used to develop heads.

 

I will check the build sheet but I am pretty sure the lifters are preloaded .030" on the exhaust and .020" on the intake. The exhaust valves are a hair longer. I wanted to keep it as deep as possible with out bottoming out the lifters. Now you guys have me seriously questioning the cam. I am sure we used the stock sprockets and a new chain. I confirmed with the customer that we did degree it with both the @ .050 method and intake centerline method. I bet I still have the events written on my degree wheel. If the cam was off, for the sake of exploration, wouldn't the tq start out much lower and then climb?

I am going to give the car a once over and take it to another dyno before I really dig into it.

 

Kind of the same thing I noticed. But that seems to be the way with most after market castings that I have seen. High short turn with deep valve set and very vertical chambers. I normally have to widen the short turn and knock it down some and put less of a slant on the straight wall and more of a slant to the long wall. Depending on the bore size I mess with the chamber or not. Then there is the valve job. Whole other ball of wax. I did notice that they had a pretty sharp edge, almost a lip, where the bowl meets the valve seat. When I talked to TEA they were confident in the head and said porting wouldn't help anything. It seemed pretty efficient on the bench so I left it.

In your opinion, what should this combo make?

 

I don't have it on the wheel any more. Done a few since then.

 

Another thought. Is the dyno brake dragging?

Last week I did a 2012 Camaro:

Ported stock heads
Low 230's intake mid 240's exhaust
Fast 102 with a ported stock t/b
1 7/8" long tubes
Stock h pipe with muffler deletes

This made 490 whp@6500 and 450wtq@5200. The 454 is only making 25 more lb/ft than a h/c/i ls3.

 

Could be. Something isn't right for sure. I am going to make an appointment at a different dyno and see whats up. 490/445rw is usually what I make on my H/C/I A6 LS3 cars and around 510-515/470rw on stick cars. That is why I am so baffled on this deal. I have to knock out a cam/EWP/UD swap on the 427 car and then I am going to go back over the 454 car.

 

Do you have another car that you know it's rwhp, and put that car on the same dyno?
Sounds like a dyno problem.