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Triple Blowthrough Turbo


Dat73z

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It is apparent I need to relearn how to drive my car. The way the turbo starts spooling in the 2k rpm range and peak torque is at 4k means I don't really need to rev it to the moon to approach high speeds, and response is really good. Corner exit is immense. The turbo spooling and BOV venting at lifts and shifts bouncing off the trees is really visceral. 

 

I think I need to find some way to record video from inside the car but I've attached a vid below of the cold start this AM and a snap from the drive. 

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@rossman yeah that's what I've read too and what I currently run BR8ES. Some people on the FB groups were mentioning one step hotter to the 7 range would be better on the street and run the 8s on the track or dyno for detonation resistance. 

 

Maybe I should just stick with 8s unless the 7s really offer much better starts/drivability. Especially since Im 8.5:1 CR and running 91 pump gas

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What was your engine setup? 

 

I read the same somewhere, probably here on HBZ that the projected tip mechanically advances your timing by somewhere around 4 degrees. The projected tip can get hot, preigniting the fuel. 

 

I switched over to the BR7ES last night, gapped to 0.028. The engine seems to idle a bit smoother and pulls to 6k without hesitation. The weather was cooler last night so not a great test, the outlet of the intercooler was frigid cold to the touch. 

 

Today I need to drive the car another 100 miles or so to pick up my 67.5 pilot jets and get breakfast with a friend. So I'll do some more testing on and off boost today. 

 

The main reason Im trying the 7s is I've noticed the 8s tend to get dark quickly, within a few hundred miles on my setup. This is probably because I live in one of the more densely populated parts of the US and traffic is everywhere. But I also noticed the plugs starting to get much darker after my drive yesterday where I was basically on boost for an hour in the mountains over maybe 2 hours of driving. The elevation change was also affecting my carb mixtures, Im sure. I think I'll stick to the 8s for track days, dyno or generally days when I know I'm going to be running the engine hard and at higher boost. But maybe the 7s would work better if I'm going to cruise long distance. 

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Did another 150 miles today and the car didn't skip a beat on BR7ES and 10lbs of boost. I think I need to get new tires. I'm currently running r888s which are fairly old. My buddy hopped in for a drive and we lit up the tires in 1st gear at 30 or 40mph and spinning into 2nd as I was rolling into it on an uphill onramp.  

 

Also considering painting the intercooler black. I thought the fairlady Z grille would obscure it a bit more but at a distance it's pretty obvious, and I prefer the OE Z look with the coolers and rad support blacked out. 

20221001_100929.jpg

Edited by Dat73z
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10 hours ago, Dat73z said:

What was your engine setup? 

Turbocharged Rebello built 3.0L P90 8.5:1 static compression. The 7s don't get as black probably because the run hot. I was running 15lbs of boost at the time. I've since backed it down to 10 to be safe and the car is plenty fast for me.

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7 hours ago, Dat73z said:

Did another 150 miles today and the car didn't skip a beat on BR7ES and 10lbs of boost. I think I need to get new tires. I'm currently running r888s which are fairly old. My buddy hopped in for a drive and we lit up the tires in 1st gear at 30 or 40mph and spinning into 2nd as I was rolling into it on an uphill onramp.  

 

Also considering painting the intercooler black. I thought the fairlady Z grille would obscure it a bit more but at a distance it's pretty obvious, and I prefer the OE Z look with the coolers and rad support blacked out. 

20221001_100929.jpg

 

I'm with you on preferring the more subtle look. Painting is fine but I knew that's what I wanted from the beginning and got my Mishimoto intercooler in black.

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@rossman it sounds like we have a fairly similar setup. Do you also have a 292-9 cam? Have you had it on the dyno? I put the BR8ES back in this AM just to be safe. Maybe when I get things dialed on the dyno the plugs will look better. 

 

@Zetsaz yeah to be honest I didn't think about it until I had installed everything lol. I'll order up a can of radiator black and maybe spray it in next weekend. 

 

Finally got notice from USPS that my electronic boost controller is coming in soon. After installing my old TurboXS controller, I think the best place to mount the solenoid and pressure sensor is behind the washer bottle where they will be hidden but accessible under the inspection cover. 

 

Inside the car I'm not sure where I want to mount the screen. I'm not a fan of having gauges and screens everywhere as I like the OE interior look. I'm thinking maybe velcro or double sided tape mounting it above the defrost/seat belt/choke lights in the center console. Or I could have it behind that panel under the pivot completely hidden since I could just pivot the panel up and hit the high or low boost setting. 

20221002_060311.jpg

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Also, on my drive yesterday I was cruising the freeway for a couple of hours and noticed my pan oil temps were 130 in the AM and 140 in the PM, and my oil cooler is already 2/3rds obscured with cardboard. 

 

I think I need to figure out a long term solution but I still need to do some more research and figure out what the options are. 

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This evening I was curious and checked the plugs. It seems I got the BR8ES hot enough today to at least start self cleaning. The porcelain was all black after my mountain run on Fri. 

 

This week I'm fairly limited on time but I'd like to install the electronic boost controller and play with the jetting a bit more. I think I need to pull some fuel out since I've fixed all the leaks on the carbs. 

20221002_200215.jpg

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Spent a few minutes this evening and looked for suitable locations for the MAP sensor and boost control solenoid. I think it would be pretty cool if I could mount the solenoid where the throttle linkage used to be. Unfortunately that area is at the firewall about a foot from the exhaust. So it's looking like by the washer reservoir is probably the best spot. 

20221003_175215.jpg

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Tonight I finished installing the boost controller. I ended up mounting the solenoid where the throttle bellcrank used to be. If it's too hot in that location I'll move it. 

 

If I get a few minutes this evening, I want to tidy up the wiring behind the dash a bit. I've added a few things since I reloomed the harness after the swap, so it'll be good to organize some of the runs. 

20221004_175541.jpg

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Last night I was able to tidy up the wiring and input some base values into the boost controller. 

 

Some tuning notes: 

 

Since I'm blowing through carbs, the onset and response of the turbo seems fairly critical. Depending on how the turbo spools, throttle position, load and rpms in the dynamic range afrs will be affected. This is why if I gradually roll into the boost at a higher gear I can hold the afrs flat at 11.5 from 2.5k rpms to redline. If I punch it, with a reasonable pump shot that isn't crazy for other conditions I could see 13afrs at 3k before the mains tip in. I read online somewhere some Supra guys like to have the afrs go slightly lean at boost onset to help the turbo spool. I'm not sure about that so I've just been tuning for 11-12 afrs across the board. There's also the affect of the pump jet size pulling in at higher engine demand. And you can also mask some of these issues by tuning richer but that affects street drivability in other ways, like transitional rich bogs and fouled plugs. 

 

Probably too much information for this post, but after work today I'm going to start street tuning the turbo response. I can alter offset, overboost and response with my evc-s controller. I can't tune boost by gear with this setup which would be more ideal, but hopefully I can alter the response over the standard wastegate performance to achieve a better result across more dynamic non-WOT driving conditions (e.g. down low and at the transition for streetability). 

 

Also hopefully this will be better than my old turbo XS controller which was definitely spiking here and there which just made things go momentarily rich as the float bowls got extra pressure. I put it back in storage, maybe I'll bring it back out for another project in another decade or two lol

20221005_061501.jpg

Edited by Dat73z
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Some initial settings to start: 

 

Low Boost A

Offset: 10%

Response Value: 10%

Over Boost Value: 3PSI

Warning Value: 11PSI

Drop Value: 100%

 

In doing some research, the Overboost Value and Response Value for these controllers is critical to get right. Or you get hysteresis in the controls like you see in the chart and can overshoot on boost, will hit the warning but won't drop boost to gate default, or have other issues. It's been many years since I've done control work/design so I'm just going to play with the settings at low boost until I get a good feel for what the settings are doing, and what the turbo likes. 

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Did some testing tonight and the HKS boost controller holds consistent boost. With the MBC I was getting random spikes, and sometimes inconsistent peak boost.

 

I really need to check for boost leaks. At WG spring pressure only I was seeing 10psi on the HKS controller. At 25% offset I was expecting to see somewhere around 12psi but I only peaked at 11.2 psi. 

 

The solenoid position also seems ok, the valve body is cool enough to touch. But of course at shutdown unless I open the hood everything heat soaks. 

 

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Finally almost at the weekend. Got word that my needle and seats are ready, but this weekend is my wife's birthday so we'll see if I can make any progress with the turbo build. 

 

If I can find an hour or two, I would like to build a simple tester to boost leak check my system. 

 

Also one thing I found interesting: I took the car out to grab a quick lunch yesterday and noticed even with the EVC-S set to wastegate mode I was seeing 10psi, which is my wastegate spring pressure. I thought I had saw a 2psi drop past the butterflies from system losses where my gauge is reading before boost control. So I'm not sure if I'm misremembering, but I guess this is what happens when it takes me months to do some simple boost adjustments. I'm going to start writing things down in a log book and keep it in the car. 

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After going hard at work for a few months I felt like I was burning out so I decided to take this afternoon off. 

 

During my grocery run I was playing with the EVC-S a bit more. One pull felt exceptionally stronger than the rest. Looking at the peak hold function, boost spiked to 16.5psi. So I think I need to tune things out a bit more. Each pull was smooth to 6-7k, no detonation that I could tell at least and AFR's were within 11-12. 

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