The twin turbo Z06 build from Hell finally done!!
10-04-2011, 12:51 PM
#41
Safety Car
Power is probably dropping off because of timing getting pulled, and the engine just can't move the air through efficiently. That's why they tend to peak at 6000rpm. Mine does the same thing with super worked LS7 heads and a custom turbo cam. Boost could be dropping off too.
10-04-2011, 05:31 PM
#42
Drifting
Thread Starter
10-11-2011, 03:43 PM
#43
Former Vendor
Power noses over for several reasons. The turbine on the APS kit is designed for a stock LS7 engine and lower boost levels (quick spool). They are small for a 454 cid engine with higher boost levels. The turbine chokes off the engine basically at higher pressures.
If you have a dyno log of the boost on the dyno it will show that the boost falls off with RPM as well.
We have some billet impellers for those turbos with new compressor covers that helps but will still have the same problem. We have done extensive porting on these APS turbine housings which help as well.
This combo would have been a better match with 427cid instead of 454cid. The larger engine esentially consumes all of the air that those turbos can effeciently produce early. What I mean is that your peak power would have been pushed up by running a smaller displacement engine.
You should also verify that your intakes are not collapsing. I have seen this a few times on the C6Z APS kit at higher boost levels.
If you have a dyno log of the boost on the dyno it will show that the boost falls off with RPM as well.
We have some billet impellers for those turbos with new compressor covers that helps but will still have the same problem. We have done extensive porting on these APS turbine housings which help as well.
This combo would have been a better match with 427cid instead of 454cid. The larger engine esentially consumes all of the air that those turbos can effeciently produce early. What I mean is that your peak power would have been pushed up by running a smaller displacement engine.
You should also verify that your intakes are not collapsing. I have seen this a few times on the C6Z APS kit at higher boost levels.
10-11-2011, 06:49 PM
#44
Drifting
Thread Starter
Power noses over for several reasons. The turbine on the APS kit is designed for a stock LS7 engine and lower boost levels (quick spool). They are small for a 454 cid engine with higher boost levels. The turbine chokes off the engine basically at higher pressures.
If you have a dyno log of the boost on the dyno it will show that the boost falls off with RPM as well.
We have some billet impellers for those turbos with new compressor covers that helps but will still have the same problem. We have done extensive porting on these APS turbine housings which help as well.
This combo would have been a better match with 427cid instead of 454cid. The larger engine esentially consumes all of the air that those turbos can effeciently produce early. What I mean is that your peak power would have been pushed up by running a smaller displacement engine.
You should also verify that your intakes are not collapsing. I have seen this a few times on the C6Z APS kit at higher boost levels.
If you have a dyno log of the boost on the dyno it will show that the boost falls off with RPM as well.
We have some billet impellers for those turbos with new compressor covers that helps but will still have the same problem. We have done extensive porting on these APS turbine housings which help as well.
This combo would have been a better match with 427cid instead of 454cid. The larger engine esentially consumes all of the air that those turbos can effeciently produce early. What I mean is that your peak power would have been pushed up by running a smaller displacement engine.
You should also verify that your intakes are not collapsing. I have seen this a few times on the C6Z APS kit at higher boost levels.
You think the intake lifters might be collapsing at the higher RPMs? Thats funny you say that because I had to take my last lifters out because the motor wouldn't go past 6,000 rpm due to that fact. That is why I have morels in the car now.
Have you had anyone swap out the GT3582R - 714568 - 10 for anything lager and still work with the APS kit?
10-11-2011, 06:57 PM
#45
Instructor
Member Since: Mar 2007
Location: Casper WY
Posts: 223
Likes: 0
Received 0 Likes
on
0 Posts
You are going to need the M/T tires for sure. I ran the BFG 345 drag radials and they didn't hook at all. I tried everything. They didn't hook as well as my Nitto Invo street tires. I am running similar hp and tq. Good luck with the rest of your build. Hopefully you can get out and enjoy it soon!
10-11-2011, 07:01 PM
#46
You are going to need the M/T tires for sure. I ran the BFG 345 drag radials and they didn't hook at all. I tried everything. They didn't hook as well as my Nitto Invo street tires. I am running similar hp and tq. Good luck with the rest of your build. Hopefully you can get out and enjoy it soon!
10-11-2011, 08:41 PM
#47
Drifting
Thread Starter
I really want the Nitto NTO5R but they don't have them in my rim size. But when I bought the tires the M/T was not out yet in a 18" rim 345 tire.
10-11-2011, 09:30 PM
#48
Le Mans Master
Member Since: Jan 2003
Location: Portland Oregon
Posts: 8,596
Likes: 0
Received 16 Likes
on
15 Posts
I think Taylor is refering to the inlet hoses or filters to the turbos. I to have seen silicone inlet hoses collapse on high or even mid boost levels. If the filter doesn't have the flow capacity or are clogged, I have seen hoses that will collapse at high RPM under the suction of the turbochargers.
10-13-2011, 10:27 PM
#51
Former Vendor
My motor is 72cc heads, 4.130" bore, 4.000" stroke, gasket 0.062" but need to check, and the JE pistons I will have to check on how many -cc they are but they are very close to being flat. I think the motor works out to be around 429cc. For some reason everyone has been thinking its a 454. I don't think I posted that.
We have a direct replacement setup that upgrades that turbo to a billet compressor wheel and new compressor covers that are machined to work exactly like the APS system.
10-15-2011, 10:49 PM
#52
Drifting
Thread Starter
Thats a 429cid roughly.
Your lifters are not the problem here. The turbo is out of steam.
We have a direct replacement setup that upgrades that turbo to a billet compressor wheel and new compressor covers that are machined to work exactly like the APS system.
Your lifters are not the problem here. The turbo is out of steam.
We have a direct replacement setup that upgrades that turbo to a billet compressor wheel and new compressor covers that are machined to work exactly like the APS system.
The new lifters did work out and the motor has no issues getting passed the 6,000 rpm any more.
What are the gains from the billet comperssor wheels and new compresser cover? Then last whats the cost?
12-20-2011, 11:31 AM
#54
Former Vendor
The inlets are not collapsing. When they collapse, you know it, and you see it, and it only occurs at 20+ psi. 800 rwhp isnt anywhere near 20 psi.
Also, boost will maintain a steady 16/18/20 psi, what ever you set it to. The turbos are starting to move out of their efficiency, thats all. The density of air, needed to keep 20 psi of boost at peak RPM is starting to decrease. IE, hot air. Its the nature of the beast. Big torque, instant boost on a stock engine, this is what it does when you turn up the wick.
Get it to pull clean to 7k, and you end up with a laggy setup, thats probably slower on the street, and less enjoyable to drive.
Also, boost will maintain a steady 16/18/20 psi, what ever you set it to. The turbos are starting to move out of their efficiency, thats all. The density of air, needed to keep 20 psi of boost at peak RPM is starting to decrease. IE, hot air. Its the nature of the beast. Big torque, instant boost on a stock engine, this is what it does when you turn up the wick.
Get it to pull clean to 7k, and you end up with a laggy setup, thats probably slower on the street, and less enjoyable to drive.
12-20-2011, 12:40 PM
#55
Le Mans Master
Member Since: Jul 2005
Location: Think BEFORE hitting "Submit Reply"
Posts: 9,390
Received 708 Likes
on
391 Posts
The last run is still significantly higher than the 3rd, making ~860rwhp at 6300rpm vs ~800rw at the same rpm in run #3.
Nice results.
12-20-2011, 02:41 PM
#56
That car should be cracking 1,000 RWHP on PUMP gas with that size engine and those turbos (and presumably the proper camshaft is in that engine given that so much work went into the engine).
12-21-2011, 01:57 PM
#58
Drifting
Thread Starter
Int open at 6 degrees close at 46 degrees
Exh open at 51 degrees close at -5 degrees
12-21-2011, 07:08 PM
#60
Safety Car
Very nice car