JZ 97 SS 1500

Inlets will not take care of the back pressure problem, I'm not sure what inlet have to do with it. The turbos with absolutely nothing on them on the inlet will not improve the situation, only make it worse. I see in the dyno plots above. Judging by the 200+rwhp drop from peak to redline, backpressure should be around 3.0-3.5:1. Better watch for head bolt stretch and heads lifting.

vegasredz062

Ok.that sounds fair... any ideas on how to drop the back pressure and let the turbos spool all the way to redline?

SpeedyD

I haven't looked at the graphs that were posted and really don't need to. People that own the APS kit know there is a restriction, it doesn't necassarily mean backpressure, if it can't suck the air in it can't make power either. There is a flow restriction, I assure you, it's on the inlet side.
I had my car on the dyno, dyno'd at 14 psi with everything hooked up, pulled 685 ish, don't recall torque, maybe a little over 700. Then we disconnected the exhaust, it bumped to 710 ish a little more torque, then we disconnected the inlets, it, as I said before in this thread, jumped 2 psi of boost, hit the internal limiter of the EBC, dropped back down to 14, back t 16, back to 14, you get the idea, still pulled 750 ish 785ish torque like that. these pulls were back to back, same day, same dyno, done within a total time of 1 hour. Not one setting on the car was changed between pulls. I had the tuner tune the car to run well on the street at 14 psi. From there we just disconnected the exhaust at the back of the H pipe, and then the inlets at the turbos, no change of anything else.

The motor is an LS6, 8.65:1, stock LS6 heads with dual rev gold springs, ls6 intake, stock TB, meth injection, and a can of torco to a full tank of gas. I will look for the dyno sheets, hopefully they are still in my e-mail.
Dan

JZ 97 SS 1500

Dan your case might be different. The graphs posted though......that is nothing but flat out back pressure. Also increasing inlet pressure means back pressure will rise as well. More volume of air in the intake means more volume in the exhaust. We test this quite often for different manufactures.......easy to spot. A system that has little to no back pressure will be fairly linear and drop very little as it reaches the redline. BTW, 200rwhp drop's from peak to redline is not an inlet restriction unless these turbos are sucking through a straw.

vegasredz062

Jose,

any ideas on how to drop the back pressure and let the turbos spool all the way to redline? is that the way the kit is made? are they the turbos? is it an easy fix or major overhaul?

I checked out your website... some pretty impressive number

AVB

If reducing inlet restriction produces more power AS it extends the upper rpm, powerband, I would think that's a good thing. Reduce inlet, make more power, create a sharper peak w/ no extension and that's backpressure.

03blkz06

Lol Adam. I knew this would happen that is why I havent posted before or made a thread about it,I was on the dyno about the time your thread was dying and didn't want to have started all over again.O well. I have prob fixed and with some new inj I think it should be able make some real fake dyno numbers!
It is stuff like this that keeps me from posting,(20 30 posts) but I still like coming on here for a good lol

Z06Samuel

Sam,
You lost power with the 3" exhaust?
Sam

SpeedyD

The way the inlets are routed and cramed under the radiator, they might as well be sucking through a staw! I have a feeling as the turbo's start really sucking they might very well be collapsing the accordian type tubing as it is already partially collapsed under the radiator. I know I personally saw big differences once I disconnected the inlets so that is my winter project, to create new inlets in hopes of increasing flow. Hoping to pull 800/800 come spring on street tune and 93, with a little torco and Meth
Dan

eb02z06

Hey Peter, I just sold my Procharger F1C, have a fresh 402 with "healthy" compression-you wanna send me a APS kit with the bigger inlets to test?

0Jeff @ TPE

You may just be able to get it done..

At least your crazy enough to try it..

BTW, The UPS truck just dropped off a really cool looking intake at my door today..

NOW IF MY G*D DA*NED HEADERS WOULD JUST SHOW UP...

vegasredz062

Sam,

no, I lost power when i dialed 13psi over 11.6 with the 3"exhaust.

meaning i made more power with the 3 inch exhaust over 2.5 ..with less boost.. but when pushed to higher levels...power droped...

Shinobi'sZ

Your dyno sheets confirm almost exactly what I stated in my previous post.

If I read what you wrote for your description of each correctly...you have test runs with the inlets and catback removed...and it didn't resolve the issue. More power was made..but that was because you had no exhaust on the car...less back pressure.

The next thing I would do is make one run with no down pipes on the back of the turbo (if possible) just to see if the boost doesn't drop off and watch for the hp to get closer to the tq. It's text book that internal wastegates when dumping immediatley into the extrude behind the turbine...create a disruptance in the exhaust, which in turn cause the turbine to slow down and obviously the compressor wheel as well...it's well documented. This is why the recommendation for kit designs that use internal waste gates is to have them dump into indepent wastegate tubes...either directly into the air or further back in the exhaust pipe.

If after that, the issue isn't resolved...then the next place to move is in playing with the AR sizes on the hot side.

IMO the APS kit is a great kit, but it needs some more work with the turbos and design to correct the issues that I see in those graphs...either individually at the flange, turbo, internal wastegate or possibly all three.

Sharing information should be to help work out the issues. It just depends on what people want.....if you got a kit that makes 600/600 you will have more then enough power for street rubber all day. If you are running higher boost to test the kit...I think it is evident what needs to happen at this point. Hopefully APS will come through and give people what they want. The fact that they are working on something is progress.

0Jeff @ TPE

Good Post..

Vince99FRC

Very hard to compare when you have 4 different people with 4 different engine combos and different exhaust setups. If you think the turbo kit is going to respond the same with the different combos you are sadly mistaken. I do think if the kit was tested on a more radical engine combo initially we would not have these issues. As you can tell on this very forum what people say they want does not always end up to be that way in the end. The final result should be a delivered smooth graph to redline. If you do not get that then you should not be happy with your combo.

03blkz06

There is only one pull with the inlets removed and the car spun on the dyno and did not get a reading. The car did not drop boost with the inlets removed like it had on the 812 pull with the inlets on. The car does pick up alot with the exhaust off, but what do you expect trying to make 700-900 rwhp through a factory stock cat back........

0EPP

If you sit back and think about all the back and forth bickering going on here, it really is hot rodding at it's finest. Every kit out there can be made better, and everyone has their own opinion, that's why we have cars today that are as fast as they are. Bob

SpeedyD

It will be the guys who go out and try modifying this kit who will be able to give the rock solid answers! Trial and error, it's always been that way!
Dan

NemesisC5

Bob, I've read on your website that you have seen 1-2psi gains on Prochargers just by changing to lower restriction K&N filters. Have you done any research as to inlet tube restriction as well?

03blkz06

Shinobi,

The APS kit doesnt have internal wastegates.......