JonoVilaca

Hi Everyone,
I am new to the form, but i hope there is someone here who can help!
Background:
I race the car in a time attack Championship in South Africa. For the past 2 years the car has been used with a progressive nitrous kit.
i decided to change to a rear mounted turbo for this season and have been having issues getting the car to boost. All the work has been done by me. I am an engineer so it has been done professionally.

Motor Build and turbo specs
1. New Oem crate VQ35DE rev up motor with roughly 3000 miles on it.
2. Motor has a BC hi rev kit
3. VQ35HR short tube headers
4. New Turbo is a 60/62 turbonetics c15 tnx ball bearing with a t3 0.65 exhaust housing
5. New Exhaust is a 2.5in(63mm) test pipe and Y-pipe that collects into a 3in(76mm) that runs through to the turbo at the back
6. New 46mm precision waste gate set with a 6psi spring
7. New GFB boost controller
8. New Z1 Motorsports 1000cc injectors
9. New Radium rails and fuel return kit
10. New AEM 340L Fuel pump
11. Intercooler is LxHxW 27.5 x 7 x 3 (700mm x 180mm x 76mm)
12. Cold side piping is aluminum that is 2.5in (63mm) from the back to the cooler and out the cooler is a 3in (76mm) to the throttle body. Only 4 x straight couplers were used - all bends are aluminum.
13. Oil feed an AN04
14. Scavenge pump line is AN08 - turbo does not smoke at all.
15. APS extended sump fitted with turbo oil return line to the sump.
16. Oil used is Motul 300v
17. Lightweight flywheel and button clutch with upgraded pressure plate.

Its worth noting i am at a high Altitude of 5,751ft (1500m)

The problem that we are only getting 7psi (0.5 bar) at 6000rpm.
Problem solving and tests done
1. Full boost leak test - system holds 15psi (1bar) from the back to the thottle pipe - so no leaks
2. Waste gate is V-band and has no leaks pressured from the screamer pipe
3. Manual boost guage was fittes to the turbo compressor, only peaking boost at 6000rpm
4. We have also eliminated the boost controller taking the vacuum from the compressor side and fitting it to the top of the waste gate to also ensure the gate is remaining closed. There was no improvement.
5. I have changed turbo to test, the test turbo was a 62/62 Precision T4 0.85 exhaust housing, we had the same result in only geting 6psi at 6000rpm.

Notes:
1. the car seems to spool at 2500 but doesnt make boost until 6000rpm.
2. The GFB when set to 10% does not generate any
3. boost The GFB when set to 100% makes gate pressure

The goal
1. I want to reach 7psi at 3500/ 4000rpm which should be good for 400hp.
2. I are aware of the oem motor limitations in terms of power and torque. I am not trying to rotate earth oem motor power limitations are fine for now.

Please guys, i am well aware that there are alot of you with tons of experience on the form. I would appreciate proper constructive and thought through advice.

Photos attached
1. Build setup from under the car
2. Dyno graph of the turbonetics ball bearing 60/62 T3 0.65

RENFRO

iTrader: (1)

Something is up with the boost controller. To eliminate anything else in the system, swap in a 9psi spring, disconnect the controller, and see if it picks up a couple of pounds. If it does, you definitely know the controller is doing something weird.

Also, that's a pretty small turbo in general with a pretty small A/R. It should certainly still be able to make more psi than it is though.

iideadeyeii

iTrader: (6)

He already bypassed the wastegate completely by putting the boost line to the top of the wastegate.
The only thing I can think of is the wastegate was tested from the output and not the input. Take the wastegate off and use a block off plate to eliminate wastegate issue. (hope you have overboost protection just in case).
Or can you verify there is no air coming out of the screamer pipe under boost?

JonoVilaca

Correct, boost controller was bypassed completely.
The gate was forced closed by putting the compressor pipe to the top of the gate to force it closed. screamer pipe and gate look brand new inside.

Picture of the gate with screamer removed. Barely any exhaust gas through it

iideadeyeii

iTrader: (6)

Put tape on output of the wastegate and see if it blows out when it's closed.
I'm not a fan of the banjo bolt type fittings on aluminum, but even if that was leaking I couldn't see that much loss in boost occurring.
Can you get the BOV to go off when you rev the engine to like 5-6k?

Is the BOV leaking/staying open? I don't see anything in your original post regarding a bov

EDIT* Also where is that catch can going? Is it just venting both sides of the valve cover?

bealljk

iTrader: (13)

I call this … Tuesday … were at 5,870ft … sucks!!!!

Thats pretty small … but if you’re only looking to take the car up to 4500rpm or so (to take advantage of peak torque) than this makes sense …

2.5” is pretty big for a DE engine. We used 2.25” from the turbo to the IC and 2.75” from the IC to the TB on the DEs … especially when you consider your .65AR hot side … not saying it shouldnt be boosting but IMO your charge pipe is oversized for your power goals and your AR size is too small …

I use 2.5” on the VHR rear mount kits and were reaching well into the 550 to 600hp range. I can link a good video on intercooler pipe sizing if you like??

What is your turbo rated to for hp / cfm airflow?

Remember that boost is wasted airflow … your engine may be consuming most the boost that is being thrown at it

All things considered, this seems about right.

Check for boost leaks on your cold side and make sure youre not losing boost from your blowoff valve not being set correctly - IIdeadeyes tape idea is a good one.
and do a once over on your waste gate, but it looks like your fire ring is installed

iideadeyeii

iTrader: (6)

I tried finding a compressor map, but couldn't find one for that turbo, but I don' think it's undersized.

JonoVilaca

The Gate came with the banjo fittings so have used what was supplied with the component.

BOV is staying closed and opening at the high rpm. Again, did a run on the dyno just making sure. I had a 50mm precision with the medium spacer put in. I have removed it since. On the weekends time attack event when i change gears it was messing around with the MAF sensor. Running such little boost a little turbo flutter will have to do for now.

Catch can vents to atmosphere, it is a properly baffled catch can and runs from the valve covers and the oem pcv valve was replaced with a AN fitting that i machined up.

bealljk

iTrader: (13)

In hindsight - a .65ar should get mid-400hp

244kw is 327hp

JonoVilaca

I have checked for leaks and the system holds 20psi (1.5bar) so no leaks.

Turbo is rated for 700-750hp.

With regards to the cold side pipe, sure i think that the smaller piper could aid slighly earlier boost, however the issue is that the turbo is not producing any boost until 6000rpm.

We have tried another turbo on the car with a larger AR.
turbo we did the same test with was a precision 62/62 T4 0.85.
we have the same result in getting the boost in at 6000rpm.
dyno graph bellow for reference.
Black line is the T4 62/62 0.85 - 7psi (0.5bar)
Red line is the T3 60/62 0.65 - 6psi (0.4bar)

​​​
what exhaust size have you put on the DE cars you have done?

JonoVilaca

Yes 100%. The goal is to peak boost at 0.6bar and maintain it to redline.
I actually did order the turbo with a 0.85 AR but it didnt arrive in time for the event, so had to make do with what i had. Since then the T3 0.85 housing has arrived. I decided that it was a better test to change out the entire turbo to ensure that nothing was wrong with the new unit and also to see what the T4 0.85 AR would do.

bealljk

iTrader: (13)

This sounds wrong … I dont think a .65ar hotside can flow enough for 700hp … this would be closer to .9 to 1.1 range


Sooooo start looking at things that you have not modified Hows your tune? How is your ignition timing?
I ask this because the DE will make 20 to 22 hp per 1 psi of boost plus 240hp base … so if you should be seeing around 380hp to 400hp.

what are you tuning with? what are your ignition timing values at 6,000rpm what fuel are you using?


I dont know how many exhaust setups I’ve done but usually 3” single on rear mount kits on the DE/HR/VHR

iideadeyeii

iTrader: (6)

It should only open when throttle is closed and intake is pressurized.
You sure it's not leaking boost out?
Where are you running the line to the bov from?