Forced Induction - insanely low power, 427 TT

Well, here goes:

Ran the car at full boost for the first time, and when I say full boost I mean 16-17.5PSI since the boost controller stopped working on its own, so I couldnt lower the boost :bang:, but anyways:

645RWHP @ 6350RPM @ 16.5-17PSI of boost on my twin turbo 427 on 93 octane pump gas WITH filters off. mid 11AFR, decent timing. I almost commited suicide.

The last dyno session the car did 575RWHP @ 7.5PSI and I thought that was insanely low, this was with the filters/aircleaners.

A few things to note are:

1- All of the dyno sheets ive seen of those turbos on 427s seem to max out at 5500 and drop off after that, yet on my dyno runs they were maxing (and flatlining at 6400RPMs).

2- The twins boosted like a centrifugal on the dyno, with boost maxing in the very upper RPM range and power was EXTREMELY linear, with the HP graph looking more like it was drawn with a ruler. So im wondering if its a case of "manipulating dyno load" to get the car to fully boost sooner, which it should do by about 4000rpms with those turbos.

3- We definitely went beyond compressor efficiency range with IATs reaching 221F at 17PSI on the top of 4th, yet thats not completely the problem with the car not making the power it should be making even at midrange with the turbos in their sweet spot. FYI, we turned IAT vs spark off and barely saw any knock even at those skyrocketing temps. My IAT sensor is working fine.

My goal was to run about 730-750rwhp on pump gas, and then add some race gas and meth (which I dont want to use on the street) and make a magical number. Especially that TTi came up with a bigger turbo upgrade for the kit.

facts:
2.5inch turbo downpipes (hard to fit bigger ones, but not IMPOSSIBLE)
wastegates routed back to exhaust
turbonetics t3/t4 .82 a/r

The only things I can think of right now, before adding meth injection and ruining my original plans are:

- dumping the wastegates to the atmosphere and lowering exhaust backpressure in that small 2.5inch pipe.
- try to fit a bigger exhaust, and run an x-pipe to equalize between both banks. car has no h nor xpipe currently.
- adjust the boost controller to 13.5PSI, and adjust the boost gain so boost ramps up as quickly as possible


Other than that, im completely out of ideas, and im short of about 150RWHP from my target HP, taking into consideration my target HP is 730-750RWHP, and not 645RWHP with no filters on.

dyno, is a dynodynamics calibrated to read like a dynojet.
ambient temps were 93deg F.

Any help would be appreciated.

post the dyno runs and hpt log files. With the boost controller plumbed correctly you should have pretty solid boost off of spring pressure.

Your ideas may help minimally but right now there is a major problem somewhere for you to only be seeing those numbers.

Once you've had enough just ship the car to me and I'll get it straightened out for you. ;)

Could be so many things. Boost leak is one. Burst knock, Knock Retard etc. If you scanned the proper things during your dyno runs, there's a good chance someone will be able to figure out what's wrong.

How does the "seat of the pants" feel on the street?

run an x-pipe to equalize between both banks. car has no h nor xpipe currently.


This will have no effect after the turbos as the turbos will smooth out the individual exhaust pulses into a realtively steady output.

The bigger exhaust would help out but IMO that is frosting on the cake. You are missing some cake right now.

Can you post your last dyno run chart?

Jim

Sounds way off. I was making over 900 wheel at 16.5#.

u may need to log the input shaft and compare to the output shaft it almost sounds like u may be blowing threw the tranny or your converter

1.lean up your afr

2. your turbos are small.

1.lean up your afr



That doesn't explain the 100-200whp the car is lacking....not to mention mid 11s isn't exaclty conservative on a high hp turbo car.

I do however agree that t3/t4 turbos are a tad small for a 427.

i lost hp going that low of a afr. put good gas in it lean it up and it will gain hp.

Could be so many things. Boost leak is one. Burst knock, Knock Retard etc. If you scanned the proper things during your dyno runs, there's a good chance someone will be able to figure out what's wrong.

boost leak is highly unlikely, especially if you see how everything is tightly fit and clamped, but I wanna check the BOV for signs of leak. Now again, it has to be too obvious if its loosing this much power, but its not.

The tuner was saying something about valve stems leaking :bang:

This will have no effect after the turbos as the turbos will smooth out the individual exhaust pulses into a realtively steady output.

The bigger exhaust would help out but IMO that is frosting on the cake. You are missing some cake right now.

Can you post your last dyno run chart?

Jim

Trust me my exhaust pulses are nothing like smooth, which also gives the wideband a hard time, im also doing it for the sake of the smoother exaust note.

boost leak is highly unlikely, especially if you see how everything is tightly fit and clamped, but I wanna check the BOV for signs of leak. Now again, it has to be too obvious if its loosing this much power, but its not.

The tuner was saying something about valve stems leaking :bang:

I have a rule not to ignore things even if they're "unlikely". That's when you go all around the world only to find out that it was something that you ruled out without checking. A pressure test of the system would be the way to find out. Cap off the turbo inlets and throttle body and put any kind of connection you choose to apply compressed air to the system. Hoses tear, blowoff valves get hung open, bad intercooler weld, one turbo locked up (highly unlikely), one turbo compressor wheel broken. Shit happens.
Valve stems leaking? Either you misunderstood him or you need to tell him to :gtfo:.
Do you have logs of the dyno runs or no?

post the dyno runs and hpt log files. With the boost controller plumbed correctly you should have pretty solid boost off of spring pressure.

Your ideas may help minimally but right now there is a major problem somewhere for you to only be seeing those numbers.

Once you've had enough just ship the car to me and I'll get it straightened out for you. ;)

Jim, you dont wanna look at the tune :barf: but again we were not tuning properly, just wanted to make sure we cleared off that machine-gun misfire issue from last time. Other than the crap tune, on WOT AFR starts at 11.3 and ends up at the high 11's because actually fuel pressure was dropping (which ill take care off).

ill re-route the boost controller (it was working fine, until I changed something). Ill have it set at 13PSI, and have the gain on and ask the tuner do change the dyno load settings, I want to see the car making max power before 6000rpms to know the graph is fine, and not not dropping at all.

right and there is a very big chance I end up sending the car to you man >.<

I have a rule not to ignore things even if they're "unlikely". That's when you go all around the world only to find out that it was something that you ruled out without checking. A pressure test of the system would be the way to find out. Cap off the turbo inlets and throttle body and put any kind of connection you choose to apply compressed air to the system. Hoses tear, blowoff valves get hung open, bad intercooler weld, one turbo locked up (highly unlikely), one turbo compressor wheel broken. Shit happens.
Valve stems leaking? Either you misunderstood him or you need to tell him to :gtfo:.
Do you have logs of the dyno runs or no?


Well, ill go ahead and check if thats the case.

thing is, why would the kit max out at 6400 and not at 5600 where it should. Im guessing the curve should start sooner, boost earlier make its power (725ish) and drop after 5600rpms to where it is now at 6400. My guess is it should make more power at 6400 with lower boost while keeping it in its efficiency range. but what do i know.

im pretty sure thats what he said :ripped:

How does the "seat of the pants" feel on the street?

a friend of mine said this is a low 700 car when we had the car at 575rwhp, and hes not a friend that drives a suburban either, he has a modded z06 as well.

I know the car will rip on the street, but its definitely not doing the dyno number it should be making before I consider it "fine"

1.lean up your afr

2. your turbos are small.

That doesn't explain the 100-200whp the car is lacking....not to mention mid 11s isn't exaclty conservative on a high hp turbo car.

I do however agree that t3/t4 turbos are a tad small for a 427.

i lost hp going that low of a afr. put good gas in it lean it up and it will gain hp.

The car will make a little more power with a leaner mixture at midrange along with the boost controller ramp and dyno load, however it was kinda lean at the top, almost touching 12 because I figured out FP was dropping up high, which I am not to worried about at least for the time being.

thing is, why would the kit max out at 6400 and not at 5600 where it should.

If you don't have solid boost control the power curve will match the boost creep.

If you have say, a solid 6psi boost from 3600-6600 it will likely peak closer to where you expect it.

Does the car pull smoothly at WOT? With those #'s it almost sounds like it's down a cyl or 2.

If you don't have solid boost control the power curve will match the boost creep.

If you have say, a solid 6psi boost from 3600-6600 it will likely peak closer to where you expect it.

Does the car pull smoothly at WOT? With those #'s it almost sounds like it's down a cyl or 2.

this is whats happening, definitely. I remember previously, the car felt like it wanted to lift itself off the dyno due to how fast the turbos spooled, I had the boost controller set-up properly last time though.

Car pulls smooth, but tuner kept on looking for issues, he says he could feel the car misfiring, well it was at the beginning, the plugs arent new ones either, we were adjusting the drivability and thought of doing WOT, it took the car about 10mins of idling for the plugs to clear up and run to redline. I used a misfire config file I got off HPT forums, and we figured out cyl#1 plug was gone, swapped that one and gained a bunch, but it was still low on power.

Now again, what im trying next is to set the boost controller and gain properly, if the car has steady FULL boost from 3500-4000 up to redline, it should be maxing at where turbos of those size will, and drop after that. The 212 degree F IAT@ 16.5psi was definitely not nice either, so im thinking MAYBE 645RWHP at a boost level way out of compressor efficiency and further away from the turbos "normal" peak HP and pump gas doesnt sound too bad lol. Will try again in a few days.

I asked the dyno operator to get the car to boost quicker with some more load, he said hes setting the car to whatever load it will see on the street, I dont know how true that is however, taking into consideration hes just adjusting the load knob and not taking the cars weight, aerodynamics and other parameters into account (which is not as simple thing to do either i think).

Anyways, coming up next is proper boost controller gain, more dyno load, and a few things checked up, fresh set of plugs and some luck? >.<

You can try the car in a higher gear on the dyno if the dyno can not load it properly. I am not trying to question your approach but sometimes people get hungup in recent events, when finding these problems remember to goto the basics, you need 4 things..

Air - Check for boost leaks (run turbos in a very inefficient area of map)
- Check for exhaust restriction (will lead to less air for same boost)
- Check for intake restrictions (will lead to less air for same boost)

Compression - Piston/Valves (easy enough to check with a leak down tester)
- ensure valve float is not lowering effective compression

Fuel - Best way is through a wideband - use two if you are unsure

Spark - Ensure your plugs are not fouled / properly gapped
- Ensure the computer is not pulling to much timing
- Ensure base timing is good
- Ensure your coils are getting the current required
- Ensure your dwell settings are correct
- Ensure no wires are burnt/damaged and resistance is good
- Ensure quality RPM signal through pull (coils are being told to fire)

Hope this helps to uncover your gremlin.

You are running hptuners..how did you log misfires..aren't you running speed density 2 or 3 bar? In speed density the misfire testing don't work? To get it to work had to put maf back on and unfail maf then could check misfire. You can also do powerbalance test with hptuners..version 2.22 version 2.23 beta don't work for me.

I had machine gun problems on my 99TT. It was burnt wires. Fixed the wires and car ran great.It was running on less than 8 for sure with the wires cooked up.
Plugs are important.Too cold and you will load up. Iridium can run colder heat ranges and not load up like non iridium. And you do need the gap down enough to not blow out the spark. .028 or so should be sufficient. You can up the dwell with hptuners also ,some guys have gone to the more powerful truck coils.
For sure you need to not lean out too much at higher boost levels. And timing can make a huge difference in power more I think then a half point or so of afr.

I would think your car should be easily putting out 700rwhp even at like 8 or 10psi.
What is the max airflow of your turbos?

And what about exhaust..cutouts? two restrictive exhaust can really hurt too.

Is the motor a newly built motor? If so, the problem you are having sound's similar to my problem I had. Have you confirmed your timing with the motor and the ecu, by using a timing light on the motor , making sure that what timing you are commanding in the ecu is actually what the timing in the motor motor is.

Is the motor a newly built motor? If so, the problem you are having sound's similar to my problem I had. Have you confirmed your timing with the motor and the ecu, by using a timing light on the motor , making sure that what timing you are commanding in the ecu is actually what the timing in the motor motor is.

I wont loose anything, so I might as well try that, but Im thinking yes its running whatver is being commanded

I wont loose anything, so I might as well try that, but Im thinking yes its running whatver is being commanded

So did I, and mine was 14deg. off retarded. 10deg. of it was my fault by the wrong value entered in the crank reference table, and after that the motor itself was 4deg. off. needless to say I was 100rwhp off on the dyno until I fixed the timing issue. Now she is a new animal!

What are the specs of your cam? Back pressure and high overlap can really kill power, and make your car build boost the way you described.

What are the specs of your cam? Back pressure and high overlap can really kill power, and make your car build boost the way you described.

If I recall correctly its around 226/230 117lsa. The cam selection is not the culprit here, I think there is a mechanical problem for it to be down this much power.

downpipes are too small

route your wastegates externally

turbonetics turbos are usually a let-down

iIs the car auto or sticK? Ive seen torque converters start to balloon and cause this.

downpipes are too small

route your wastegates externally

turbonetics turbos are usually a let-down

That would be one of the first things ill do.

iIs the car auto or sticK? Ive seen torque converters start to balloon and cause this.

stick here.

If I recall correctly its around 226/230 117lsa. The cam selection is not the culprit here, I think there is a mechanical problem for it to be down this much power.

quite right on the cam specs jim.

With the IATs that high and the boost coming on slow I would point to a boost leak. Did you pressure check it yet?

Is everything grounded properly - including all the appropriate leads on your engine harness, the fuel pump, and especially the block?


Fuel - Best way is through a wideband - use two if you are unsure

Spark - Ensure your plugs are not fouled / properly gapped
- Ensure the computer is not pulling to much timing
- Ensure base timing is good
- Ensure your coils are getting the current required
- Ensure your dwell settings are correct
- Ensure no wires are burnt/damaged and resistance is good
- Ensure quality RPM signal through pull (coils are being told to fire)

Hope this helps to uncover your gremlin.

With the IATs that high and the boost coming on slow I would point to a boost leak. Did you pressure check it yet?

Id love to beleive its a boost leak, but I cant get that in my mind because a visual inspection doesnt seem to show any signs of a boost leak, and im assuming for what happened to happen the boost leak should be quite big and obvious.

I will still however check for boost leaks, and well see what turns out.

Guys, I mentioned in the initial post that the car was running with no air cleaners, I didnt mention however that the car was not running any inlet pipe on the turbo itself, so this is how the car looked like:

http://www.turbotechnologyinc.com/c6/passenger_side_manifold.jpg

http://www.turbotechnologyinc.com/c6/drivers_side_manifold.jpg

Is that part of my IAT problem right there, the fact that the turbo inlet surrounding was being heated up by the manifolds as well?

I took the previous pics from turbo technology's website.

get bigger turbos

or

make the engine cubes smaller

get bigger turbos

or

make the engine cubes smaller

possible.


yet second option is too late to do. Now even with the suggested solution, there still is something definitely wrong which I want to figure out at least before I even think of bigger turbos. The next culprilt would be the 2.5inch downpipes on a 427 :bang:

leakdown test the engine

possible.


yet second option is too late to do. Now even with the suggested solution, there still is something definitely wrong which I want to figure out at least before I even think of bigger turbos. The next culprilt would be the 2.5inch downpipes on a 427 :bang:


i still cannot see where u listed the actual compressor wheel size???
i know there are t3/t4

at a guess u have 57mm comps, and stg3 turbine wheels...which u will probaly never get it any better..

find out what comp wheel size ......

It's a TTIX system and is capable of ALOT more power than it's currently producing.

Doubtful, but one locked up turbo would cause a problem and the other turbo would over spin to compensate. I would expect that to raise your IAT's. The bottom line is we can only provide ideas. You're eventually going to have to get in there and start testing everything. Just passing a visual inspection doesn't cut it. I had a boost leak from a bypass valve stuck slightly open. Make sure your turbos spin freely and there is no shaft play. Then make sure all of the fins are on the turbine and compressor wheels with no signs on engagement with the housings.

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...

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?

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.

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.

test for boost leaks with one of these. youd be surprised what leaks youll find.
http://www.z1motorsports.com/product_info.php?currency=USD&products_id=1867

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.

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.

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.

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.

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.

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

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...

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

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

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.

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.



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??

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 :(

What are your plans now? Bob

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.

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.

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.

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.

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.