I hate sharing this because I've never seen anyone else doing it but I used a dual wastegate system on the only read turbo setup I did. We had issues with excessive backpressure, hitting 65 psi at steady state WOT. This was a 422" engine for what it's worth. 65psi under spool is ok but not for steady state.

The wastegate at the turbo controlled boost in the traditional way, it was fast acting. The other wastegate was right after the cylinders merged into the single pipe. This one bled off a huge portion of exhaust so it didn't have to travel through the long ass pipe one it was at full boost. Backpressure dropped to a more normal 10-12psi without hurting spool. The goal was to use only one wastegate at a time so once the primary gate at the engine began to receive signal to open the one at the turbo was fully shut.

I messed around with only the gate at the engine and it worked but boost would overshoot just slightly. I think it would have worked with just the one with more tuning but I was afraid of overshoot in the higher gears.

That was a neat system because the wastegate combined with another system ended up giving decent spool and normal backpressure but the initial setup was a nightmare.

I guess by saying the wastegate was wrong I should have said it was unimaginative lol.

 

I'm tuning my first boosted J35 and so far it's going fine. First I had to get all the knock counts to show on the flashpro log and I also had to get the get the AF from the gauge to match the log. Then the tuning can start... I don't rely on any ecu to remove timing once knocks occurs since they are too slow to retard timing... I tune to get zero knocks every time... if high IAT/ECT are a problem I request for aftermarket parts or modifications to cool things out. And this is not my daily job at all, I do this because I like it a lot, when I will feel it's a job it won't be fun anymore and I won't bother doing this...

 

Since the NA J35 are knock monsters on 91 octane we need to wonder how someone would boost those engines... but some do they must be fun while it last but there is now way to keep them reliable unless the compression is lower to 9.0-9.5max. I only touched one boosted J35 and the previous tune did not catch the knocks and timing was very low. I have raised the timing by 3-4 degrees and got the car to be knock free at 10.6-10.8AF on 91 octane and no watermeth... Exhaust valves must get very hot from high EGT but so far it seems to be ok... IAT corrections tables helps too but still get high ECT very quickly. A new rad and fans are being installed now and we will see how it goes from there. It also goes without saying that the builder must have though of leaving additional exhaust valve lash... that would explain why this engine is still pulling strong

 

I've seen these j's be really temperamental concerning timing and cause excessive high ECT's. As I've mentioned before, this if course can result in a domino effect of detonation or preignition if left without remedy. And when it's gets going too far, the biggest damn fans and radiator in the world isn't helping anything.

 

Dom, what sort of coolant temps were you seeing?

 

Anything higher than the rad and fans can handle is too hot for me so it was higher than 100C...

 

Agreed. Have you guys ever looked at airflow through the radiator? What I'm getting at is now you have a front mount blocking a lot of the air while you're also making double the factory hp. I've had setups that relied almost 100% on the fans and on that case it requires absolutes huge amounts of air from the fans. One thing that worked very well on my GN was to use an intercooler with a much thinner core. I made up for it in the other dimensions with it being around 46"x32" not counting the tanks. It is HUGE but it's only 2" thick. It went from running 190F if I never hit boost and 220 under short runs under boost to sitting on the 160 degree thermostat at all times except for when I did a full 1/4 pull in which case it would hit 175F but actually cool down in about 2 minutes back to 160. It was a massive difference going from a 6" core to a 2" core where the end tanks were spaced far enough apart that they didn't block the radiator as now the intercooler core is as wide as the radiator and even taller. Just a thought.

Also, are you running coolant? I always run the bare minimum for water pump lube. I currently have a 70/30 mixture in favor of water in the TL and straight distilled with Water Wetter in the GN. Also, just having both fans running on high at all times anytime the coolant fan is supposed to be on really helps keep temps in check before they can become a problem. It's good practice anyway with all of the additional exhaust plumbing under the hood.

Looking forward to your results since you seem to have a good handle on things.

One question though.... Most people don't want a setup that relies on meth to not blow up. However, with the incredibly low timing levels people are running, and since this can cause preignition that will go undetected, I wonder if you're not better off running meth so you can run more timing and not have glowing hot exhaust valves that could be causing many of these problems. I'm wondering if there comes a time when we have to face the fact that boosted TLs need at least 100 octane or meth injection even if there's no detonation. I've had my timing on my other car backed off to where some of these guys are running it and it wasn't pretty.

One last thing, back to airflow, in just about every car I've run,
Just extending the air dam (the part under the radiator that scrapes over bumps and driveways) down a couple inches has always helped lower coolant temps when at speed on cars that were struggling.

 

Cooling system upgrades are done holy crap the fan we got (could only use one of the 2000+ cfm and one 1150 could not fit both of the big ones) is like a freaking hurricane under the hood I think it could propel the car by itself LOL.
So now to the water meth injection we have been researching (Google style) and it seems like for detonation and cylinder temp reduction the direct port injection is much better than a single pre throttle body injection point, and I'm concerned about the intake manifold being able to distribute the mix evenly seems like we have Cyl. 5&6 getting higher boost or something causing them to be more prone to detonation.
DO YOU THINK IT'S WORTH THE COST AND HASSLE ?

 

I wouldn't do direct port meth. Uneven distribution of meth is what you want if you have uneven air distribution. Basically the cylinder that's getting more air and leaning out will also be getting more meth to help out a bit.

Plus you want to give it enough time to cool the charge air. With mine 6" before the TB, I see lower than ambient temps at 25+ psi at the plenum.

 

Everything I read says direct port is the way to go for detonation control and a lot of people do both pre throttle body at lower boost and both port and pre TB at higher boost levels ?

 

go with aqua mist system

http://www.aquamist-direct.com/806-4...rt-bundle-new/

 

I too was on the direct port route years ago till I started reading all the problems people have with it. I instead ended up injecting a very small 150cc spray pre-turbo and the rest 8" before my throttle body. I also prefer to run 70/30 mixture of water and denatured alcohol (be sure to purchase the 90 proof not the 70 proof) since it is not as volatile as methanol. YES I didn't get the added power that comes from the meth, but I didn't care. I wasn't running the set-up for power, I was running it for safety.

Later I ended up trying a complete pre turbo water injection system that was all mechanical with no pump (just used the turbo's own boost to inject and a special mixing nozzle) and that actually worked well also.

I agree with IHC though, I would avoid the direct port.