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BUILD The misadventures of sktchys turbo 3800 catfish

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
I wish I remembered which set of heads I stuck my 105s in 😂 I agree the 136s are probably gonna be a little heavy for the single chain but maybe on stock rockers, probably still be hell on the dampener and lose even more lift off the stock cam due to deflection now that I think about it. If anything I should probably dig out my 1.9 modded stock rockers or just leave it the hell alone and get it dialed in.
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
I think I've talked myself out of messing with it, if everything stays working right it should be plenty of fun the way it is with a real turbo and lower compression this time around and ideally stay together for a while.

Having it seemingly fixed and not being able to play with it is driving me batshit though.
 
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sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
Took it out for a little drive today even tho the road was gross, I couldn't stand letting it sit any longer. Hint of idle miss that comes and goes I think I can attribute to the tps sender reading low like .45 volts at closed position, little bit of a coolant leak under the upper intake under where the thermostat sits. Exhaust flopped backed down again and tore my knock sensor wire loose. But I managed to give it just enough to spool about 3psi and hear the bov do it's thing and it still seems to be ok and still had over 20 psi of oil pressure afterwards.

Steps in the right direction I'll sort out another day I suppose.
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
So I'm digging back into my pcm and going to try and use the Bosch 4.9 sensor wideband to try and simulate fuel trims and eventually pin my 4l60e in so I dug up some pcm pinouts. Figured maybe somebody else will appreciate them as much as I do since it's not even listed in the repair manual. Screenshot_20230215_180924_Firefox.jpgScreenshot_20230215_180938_Firefox.jpgScreenshot_20230215_180907_Firefox.jpg
 
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sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
Ah
bs009 bs009 wiki material id say
More or less. I think I can run my narrowband output to the high side of the signal and the low side will need the ground output and a solid ground and then it should even switch to simulate a normal narrowband. We'll see if it works when I get around to pulling the connectors out of the pcm to pin the signals wires back in I guess
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
So I finally got it out of the garage today after getting the exhaust hung up better. It's still not ideal but it doesn't drag unless I hit a big dip at least. Lowered life I guess lol.
Snapchat-2093397389.jpg


I finally put my 275s on the back which didn't help my height issue but the car is way firmer in the back now and after it tried to kill me I wasnt fucking around on the 235s anymore.
Snapchat-335207343.jpg

After that I beat on it around town for a few hours and ran into my friend with a 700hp rcsb, actually hung with him til I hit the top of 2nd gear and then he was just gone. But it still felt pretty good to have the front end up there for at least a second. I put about 80 miles on it tonight and beat on it hard at just under 10 psi and 15⁰ of timing. It's still way rich because I fired the fuel cannon at the maf after redoing injector data to get everything where it should be. But this 6765 turbo just shits on everything else I've ever had as it moves a ton more air and feels like the difference is real but it could be because I haven't driven it forever.
Snapchat-1475371439.jpg


Still absolutely stoked to be able to go out and rip on it without it breaking. Easily the most fun car I've ever had.
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
After doing some playing with it some I think I probably overshot the turbo. It doesn't spool at all with no load anymore and it wouldn't really build boost in 1st when I was driving it around but as soon as you lay into 2nd it's there. On the flip side of that is it'll sure be a hell of a lot easier on my trans and rear end for it to do boost by gear on its own. And if it's taking almost 10 lbs and 15⁰ on trash 87 e10 with no knock it's doin better than it ever has before. Lower compression ratio and retarded L67 cam gear also impacting both factors here as well I'm sure but it feels like it wants to run this time.

Also a question as to whether or not dhp has a rolling idle table for these like say an ls car would. When the car is still rolling it drops rpm back to stock 640 and oil pressure follows (doesn't show commanded any different). When completely stopped it goes back to 900 where I have it set and I have 30 psi hot even after a good pull. Unless I need to try toying with decel settings that seems like the only other vss based value I could change.
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
The only thing readily available is the Amazon phab kit with a cheap gate and t70 for like 600 bucks. You'll wanna move right bank O2 further up so it gets all three cylinders instead of just number 6 and cut the bullshit ends off of them and re v band them so you can put the turbo going down instead of up. There's plenty of room behind the radiator and you should be able to just 90 out of the turbine housing and go straight back where the AC compressor used to be for the downpipe. I'd say .68 ar hotside t4 with a 3 inch v band in somethin 66mmish. This 6765 turbo I have would be great if it wasn't .96 ar but there's give and take. I don't really like a 62ish wheel because then it wants to build boost too quick and the l36 rod bearings don't appreciate it.

Throw the china wastegate and t70 in the trash and get a 39mm precision and somewhat decent turbo like a forced performance or vs racing when they're on sale and you'll be a lot happier than if you spent 100 bucks less on ebay
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
So I haven't posted much about this car because I thought i had it basically dialed other than the decel dropping idle thing and I've been playing with other things lately. Shot the file and log over to a friend who made some changes with injector data and no matter what I did with maf or ve I couldn't get it to quit missing. Loaded the old file back in it and sure as hell it went away but now I'm seeing a couple degrees of kr and it's really not happy on decel. I think it being cooler out today has a little bit to do with it but I'm only really seeing kr when it spools and then it tapers off as expected.

But there has to be a rolling idle table in this thing that hpt cant access. The drop in rpm and weird fueling stuff only happens with it in neutral or the clutch pushed in while rolling. As soon as it comes to a dead stop everything's peachy again.

Of course it could be due to running in open loop, it could be due to the wheel speed sensors up front being unhooked, or it could just be somethin I have fucked up. But regardless I'm gonna have to iron it out or it's gonna drive me batshit because when rpms go so does the oil pressure, and I'm not playing that game with this thing anymore.
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
Ya know, I think so. Pressure still probably drops to 15 or 20ish when warm at hot idle but it just hits the red line when it drops down to 5 or 600 rpm and I haven't seen the check gauges light for a while except once it died after a light pull. I also haven't really been taking it past 4700ish because you can kinda feel torque flatten out and there's just no reason to be hitting redline and power shifting at the moment. If I had to guess it's somewhere around 270 wheel at 9.5 psi which seems reasonable.

Anyways here's a shot of when it happens. I can't pick out anything abnormal at all other than the rpm dip and sometimes it goes dead lean and sometimes it kinda stays where you'd think it would otherwise
Snapchat-895256578.jpg
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
Holy shit wiring the narrowband output from the wideband into the pcm actually worked...it's kind of slow and a little stupid so you'll wanna get things straightened out in open loop before trying it because it's gonna rock back and forth on rough spots, and when it goes closed loop it's going to go 14.7 stoich no matter what you have commanded. I tried 14.1 and it stayed at 14.7 and tried to tell me I was lean. But it actually fucking worked and switches like you'd expect it to.

It's also all but cleaned my issue up, seems like it just wanted to be in closed loop which is somewhat annoying because my Buick doesn't seem to give an absolute shit about things like that for whatever reason. Still tho. This is a huge win for this car.
 

sktchy3.8

it'll work til it doesnt
TCG Blue
Jul 27, 2021
3,776
6,470
So I took the car in to work and strapped it down this afternoon. I was pretty spot on with my guess of 270 because I started out at 261 and ended up where it did. Not too shabby for 87 octane and 11.5 fuel, leans out to 11.8 to 12.1 on the street so I think I might just leave it alone for a while until I decide to put some corn in it. It feels really good now and is pretty safe around 13.5 or 14⁰ but man does this thing flatten right off after it gets there.



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