Help with tweaking a 3.9 liter
 

1st post, I have done some researching and have some questions...

I love my 4BT in my '71 Toyota Land Cruiser wagon. Only thing is up here in the altitude 5000-8000 feet in Utah (maybe it's normal?) but my boost is only 12 PSI or so. It is a '91 4BTA 120 hp factory, pretty sure it's the Holset H1C turbo...

Trying to figure out a way to mildly tweak it. Fuel economy is somewhat important but I need probably another 20-30 hp and that is it, I do not need it bombed. For last three months I had a straight pipe. Finally had a fancy 3" exhaust with straight magnaflow bent up but it reduced power significantly :(.

I have read all of the Bosch VE mods, I have a intercooler out of a Volvo station wagon, boost and EGT and Tach. Turned up boost screw this afternoon only about 35-40 degree turn. Made a difference except I feel like I don't have the torque I had before. Going to turn up the smoke screw a hair and see how that turns out... I think because of safety EGTs it was actually set about 25-35 degrees back from where it should be at the factory (I understand that it is vertical from the factory?)....

I've also read about different injectors, throttle plates etc. I do not need anything fancy... This is where my questions are....

Problem is my exhaust comes darn close to the firewall, so much so that I use heat wrap to keep temps down. So, it cannot move even an inch back so I think I am limited? I have a 3" exhaust output with clamp style.

My thoughts are:
1) Smaller housing - how does this work exactly, I just swap off the rear and look for something compatible with my H1C? Like a 12cm?
2) The HY35 everyone recommends except that will move my exhaust back, right?

3) Maybe some injectors?


I'm interested in all of your advice!

Pretty sweet rig, daily driver with a NV4500...

turn the smoke screw a few hundred hairs, turn the power screw a little more ;)

any smaller housing you go with is going to move the exhaust back a little... not a lot... about an inch or so... you could put a 12cm non-wastegated housing on your H1C, and that would make a nice difference in spoolup. HT Turbo has them brand new for $155.

DEFINATELY some injectors! :cool: get some of the Lucas POD's

The HY-35 will move your exhaust back a little. To bolt it up you will need a different housing backplate, the stock backplate has an elbow cast in that hooks to the 2nd gen downpipe. the 9 cm housing on the HY will make a huge difference in spoolup, and the more efficient compressor will help once you start putting more fuel to it.

The POD injectors would make a huge improvement, since you only need 4 you should be able to do that for well under $300.

The smoke screw doesn't do anything for power, it's just to help the turbo start spooling. You need to pull the AFC cover off an make sure the fuel pin is set to the deepest side, and back the star wheel down a couple of turns as well.

Im not sure what exhaust housing you have now but 16 CM and up all have the same outlet flange and wont affect firewall distance, the 14 CM down moves it back about 1 1/2 inches.
The smoke screw, dont mess with it, back it back out where it was, it wont increase power and will make smoke. the power screw, turn it in, you will see that as you do that you will have to turn your idle down.
You can also to a real easy mod. pull the diaphram cover off and turn the eccentric cone to where your fuel pin rides on the lowest part of the ramp. these are all free mods.
A friend recently bought an old frito lay van with a 4BT. we cranked it up one night just for fun.:o We made that thing fly.
Good luck

Thanks guys I appreciate the responses. Engine probably had only 60-70K miles on it at most when I got it. The only problem has been mild white smoking at startup (normal) and a little around town, not sure what shape the injectors (or the pump) are in but they work. I may have the injectors rebuilt but would probably spring for the PODs or something else similar (recommendations and places to get this stuff?) if/when I upgrade.

I'll attach a link below regarding the firewall issue. I had to hack a corner of my firewall and I didn't move it back far enough. If I'd know about the turbo housing I probably would have moved it back even farther and would probably have to yank the engine to do it again. So I think I am stuck with my turbo (H1C non wastegate I think at 16cm3). Bummer :(

I will try tweaking the pump a little indeed. I do not want to blow anything up (I hear lots of dangers on these) and I doubt I would but I like the clean diesel look (aka not a ton a smoke), decent EGT's, good mileage and reliability. If the pods are squeezing out more fuel but I don't have the boost then won't it smoke and cause more EGT's or is there something special about these injectors?

Also, this guy claims better mileage and more power, is he full of sh*t?

http://cgi.ebay.com/ebaymotors/ws/eB...sPageName=WDVW


Thanks guys,
details on the install here:
http://www.pirate4x4.com/forum/showthread.php?t=201165

you could take a 12 or 14cm non-wastegated housing and have someone chuck it up on a lathe and move the v-band flange forward an inch or more in order to yield the same clearance as the existing 16cm housing.

Forrest

That's a good idea, Forrest.

The Ebay guy is lying about the first part, but he's not lying about the power.

That is a real nice conversion, you did a great job.

If you don't want smoke, be very careful playing with the smoke screw and star wheel. Also don't get the POD's, get Bosch 190's. Not as much power but better smoke control.

smoke is good[eyecrazy] [eyecrazy]

The PODs make great power, they will smoke quiet a bit and I lost 3 MPGs across the board.
I think I would try the powerwagons AKA 185s or try EDMs. the 185s give about 25 to 30 HP to a 6BT, the EDMs can be bought in a variety of configurations.

Can someone point me to a company or vendor who carries this stuff?

PDR is a good source.