DrTurbo

iTrader: (3)

T3/T4's are not what you want on a motor of that size. Your backpressure #'s are well over 2:1 I can assure you. We have seen this on several setups using T3/T4's. downpipes will help somewhat, but your still flowing 427ci's worth of air through T3 flanges and small turbine wheels...

TT350

Not try to doubt you DrTurbo but I think the turbine
is a stage 5, it’s no much smaller than a P trim.

Some of the guys running the APS kit with the LG
up grade make 700+ hp with motors north of 400cid.

The stock APS turbos and the LG’s look like a T3 flange
and the turbine doesn’t look all that big.

How are they making the 700+ #’s with them?

dan03mach

iTrader: (1)

what size turbos are you running? I would have figured a 427ci motor with twins would make a hell of a lot more then mid 600rwhp rang at 16psi. I say that because my 281ci mod motor made 650rwhp and 608rwtq at 15psi with a single 76mm Turbonetics turbo.

qqwqeqwrqwqtq

T3 hotside is not ideal for 427ci but the fact remains that there are similar combinations (427/TTIX) making 850+rwhp at that same boost level.

So, while the turbo size may not be ideal there is still around 200hp missing from this combination and it's not going to be fixed by dumping the gates to atmosphere or making bigger downpipes.

The combination, at this point, does not need to be changed but the problem needs to be found. Boost leak, engine problem, not running on all cylinders, the possibilities are endless but someone who is experienced with building/tuning these combinations should be able to diagnose the problem.

cullen

iTrader: (3)

test for boost leaks with one of these. youd be surprised what leaks youll find.
http://www.z1motorsports.com/product...oducts_id=1867

ayousef

My list of things to do are:

1- compression test (I think im gonna find something here, since I got some white smoke coming out of the left tail-pipe when under throttle)
2- boost leak tests
3- check compressor and turbine wheels for any signs of damage
4- check the downpipes - which are customized - and might have inner welds that are choking the 2.5inch pipes even more.
5- adjust boost controller and boost controller gain to get full boost as early as possible, and not at the very high RPM range or a range out of compressor efficiency.
6- install the turbo inlet pipes and in turn not suck in the extremely hot manifold/exhaust surrounding air.
7- my own intercooler mod. This would definitely help on the road at speed
8- dump wastegates to atmosphere and reduce exhaust backpressure.
9- and a few things here and there.

all in all, ill check for damages (hoping not), then work out the obvious things such as boost ramp up, IAT, and tune.

PS. the tuner said that there was about 25 more RWHP from adjusting the tune, but we didnt try that. Basically, my understanding that a power curve with such small turbos FLATLINING from 6000 to 6400 is definitely sign of improper boosting on the turbos.

On another half way pull the car made 540RWHP at 4100RPM which sounded about right since the car made very little boost at that RPM, whats happening in the mid to higher rpm range is what im chasing right now.

venom ws7

iTrader: (13)

ayousef good luck man I hope you find the problem with your setup 800rwhp on pump gas shouldnt be a problem.


Keep us posted....

Hussam.

ayousef

did the compression test, most at 115, one at 120 and one 130, so they all seem to be in-range for my low-comp motor.

checking a few things that I think might have been causing this, but only time will tell... Its going to be two more weeks before I can get an update though.

HUNTER02SS

iTrader: (24)

Check you TIMING as well. If you are going thru all the rest, you might as well make sure it's dead on as well.

sultan(ZR-1)KSA

can you please show us your DYNO HP tuner LOG ??????

crashly

^^^^^
good post
my 355 cube even layed over with same turbines...

ayousef

I hope those posts are directed towards the guys that BUILT the kit for this CI engine and not me.

As for my end, project is canceled.

even a supercharged motor makes more power per pound of boost with all the so called parasitic loss than this choked to death engine.

If replacing the turbos was an option, I would have done it along time ago. you can't even squeeze you're finger between the turbos and the chassis, its that tight of a fit.

venom ws7

iTrader: (13)

Sorry to hear that Ayousef I was really looking forward to seeing some results of that beast you did your best.
Isnt there a couple of C6 ZO6 With the same turbos you have making over 800rwhp on pump gas??

jay_rich

iTrader: (8)

Im gonna say for a 427 your gonna want like a 70mm with a .68 housing.
This is what I was gonna use on my 383 but im sticking with my single.

Just for reference my 383 Lt1 made 583rwhp on 8psi

74mm t6 turbo
8psi
91 octane
10.X:1 afr (waaay to rich)
26* timing

Jay

EDIT JUST NOTICED THE PROJECT IS OVER

EPP

iTrader: (22)

What are your plans now? Bob

ayousef

bob, thanks for asking, but trust me im just as clueless as you are in terms of what happens next, I know for a fact that there are two-three SMALL fixes that would make the car work perfectly fine, I went a far step to get the car to operate fine - in our weather - in terms of cooling and all that, so much creative work on the car that I never mentioned here, since I planned on doing that at the end, but its a pain in the butt honestly, and I dont blame myself AT ALL, its always the shops doing what they're not supposed to, or fixing one thing and breaking 10 other things.

I think I have a -6 fuel feed line!!! The shop probably thought this is a camry when they did that, and a - 8 return!!! I usually dont look for small issues here and there assuming - seems thats a bad thing to do - to assume people know what they're doing. The other funny thing I found two weeks ago was that I was running low-z injectors with no converter lol, and guess what the car survived for 5 days without blowing anything up until I figured out the injectors had a big sticker saying (ACCELERONICS), they confused the huge 100lbs low-z for high-impedance thin 60lbs Seimens ones lol.

Im taking a break before I decide what im doing to do, for the time being if I find a buyer ill probably take the offer.

VINCE

iTrader: (1)

Dont mean to beat a dead horse, but I told you to check for boost leaks a long time ago when you first gave your initial dyno #'s. My car did something similar when both my BOV's failed. I kept turning up the boost and I was WAY down on power. Fixed the boost leak and picked up almost 200rwhp. Saying that everything looks tight means nothing. Everything was tight on mine and I still had a boost leak. Try the boost leak tester I mentioned in the other thread.

Even my Supra had a boost leak recently. Everything LOOKED tight, but I knew something was wrong. I pressurized the system and made the boost leak cocktail of soap and water and started spraying. Found my boost leak.

MoeDenali

ayousef, as VINCE mentioned do leak test, i faced same problem with my porsche i checked the pipeing and everything seemed to be ok, when i did the leak test i found the coolers are leaking and cousing the problem, you don't know, try it you will not lose anything.

TT350

I could see how a bad BOV would cause this but a little seeping here and there?
The leaks would have to fairly large I would think to cause major power losses.

ayousef

Now guys, my power losses wouldnt be so bad I THINK, if the boost controller was working in the first place, the car was boosting REALLY SLOW, and tops off at an RPM where the turbo output is known to drop on its face (this specific turbo system). I compared my graph to other graphs with the same turbo system, and the numbers were as follows:

i was, 100rwhp at 4000rpms, and a 100rwhp less at 6400RWHP, taking into consideration the other vehicle with the same mods had meth, while I didnt. Now everything in between 4000 to 6400rpm was out of whack, but id blame that on the boost controller

Im running on wastegate springs right now and I get full boost at say 3200rpms, so with a properly dialed in boost controller and gain, it should even boost earlier and carry on boost and spit out a proper power curve, but again im just loosing interest in the project, but at the meanwhile im taking a break so I might change my mind and give it another shot soon.