1994 Infiniti Q45 Rear Mount Turbo full writeup w/pics

[Carl H]

very cool indeed but a few points...1) pressure check the charge pipe, the welds on your exhaust and charge piping look porous.2)get a wideband asap...narrowband is a complete joke.3)you need to do a maptrace if possible and back timing off, 46* is alot of timing even with ~4psi you idealy need an egt gauge to make sure you're not roasting your pistons.

keep up the good work, if you need help constructing a map lmk.

[elwesso]

very cool indeed but a few points...1) pressure check the charge pipe, the welds on your exhaust and charge piping look porous.2)get a wideband asap...narrowband is a complete joke.3)you need to do a maptrace if possible and back timing off, 46* is alot of timing even with ~4psi you idealy need an egt gauge to make sure you're not roasting your pistons.

keep up the good work, if you need help constructing a map lmk.

Carl I may hit you up this week, we're trying to work out information on our BINs and xdf's, some of the maps are kinda weird.

[qsiguy]

very cool indeed but a few points...1) pressure check the charge pipe, the welds on your exhaust and charge piping look porous.2)get a wideband asap...narrowband is a complete joke.3)you need to do a maptrace if possible and back timing off, 46* is alot of timing even with ~4psi you idealy need an egt gauge to make sure you're not roasting your pistons.

keep up the good work, if you need help constructing a map lmk.

Pressure doesn't seem to be a problem at this point, I did check part of it and rewelded a few spots that had small holes. I still need to redo the front section of the compressor pipe as it currently hangs too low.

The narrowband was just to fill the gauge hole, I picked up my O2 bung yesterday so that will be going on soon.

Timing on that version of ECUTalk isn't accurate. It's 35* more advanced on the gauge than it actually is. I just downloaded the new beta of ECUTalk that lets you adjust the timing gauge to adjust for US specs. Apparently it's a different setup for Australia (I think) where the designer is.

I would love some assistance with the tuning. I have some equipment to burn EPROMS and some maps, software, etc. but Wes and I are having a little trouble sorting it out. I am having a little trouble burning EPROMS with my Willem programer. I've noticed that when I do burn a chip then download it and compare it to the original bin there are some changes and I can't figure out why. Maybe my offset is messed up or something. I'm following procedures from hybridka.com (I think) but it's not going smoothly.
Modified by qsiguy at 8:39 PM 1/1/2010

[elwesso]

shane robert gave me a value to put in for the offset, i cant remember off hand what it is. Im going to get back to you in a massive email later this week with some more useful information.

[qsiguy]

008000 is the typical offset for the SST27SF512, or any 512 chip I think. My software/burner puts that in automatically when I select that chip. I've tried some manual offsetting a quite a few various things and it's still off. What burner/programmer do you have? I'm considering getting a different programmer but I'm sure the one I have will work, I'm just getting frustrated with it and the support and technical information is limited.

[qsiguy]

Just ordered the Moates BURN1 programmer. Hopefully I'll have better success with that one.

Anyone want to buy a Willem Dual Power EPROM Programmer?

[BallzDeep1.9L]

well done.. i have seen some guys who also do this on LS1 F-body's becuase of the issues od space under the hood.. a friend of mine will also be doing a rear mount turbo set-up on his LS1 camaro.. ill be sure to link him to this thread.. good post , +1 to you

[Soulpwr]

[qsiguy]

Time to take care of the PCV system. Messing with a new ECU map this afternoon and switched to the 5 psi ( ) stage 2 and throttled up a couple times. A ways down the road noticed some smoke so I pulled over and popped the hood. Oil all over the pass. side of the engine bay. The dipstick had popped and oil sprayed all over.

I knew it needed to be done but was hoping it wouldn't cause any problems until I got the boost up to 6-8 psi. Stopped by the store on the way home for a few cans of engine degreaser and cleaned it up. Guess I'll take it easy until I get the crankcase breather installed.

[T45]

Careful, that could also mean some nasty ring blow-by. I would run a compression check on all cyl's before continuing.

[elwesso]

shouldnt the PCV valve prevent a positive pressure from getting into the PCV system?

[ScottJackson]

Careful, that could also mean some nasty ring blow-by. I would run a compression check on all cyl's before continuing.

I agree. You've heard it ping and had it cut out (likely from going lean) once already, if I recall correctly. I doubt the cast Q pistons are very tolerant of that. Still, I'd just run it and work over your crankcase breather system to see if it fixes it. Or, let it idle for a bit, shut it off, and quickly take off the oil fill cap. If steam comes out, you've likely got some bigger issues. For PCV, you've probably looked it up, but the way to go is to run a regular PCV valve so when the intake is under vacuum it will pull crankcase vacuum. Then, when the intake is pressurized, the PCV valve should keep the boost from getting into the crankcase. The hose to move is the breather hose that goes from valve cover to anywhere that may see boost. That needs to be moved to the turbo inlet pipe (makes vacuum under throttle) with an oil seperator if needed (so you don't suck oil from the valve cover and into the turbo/intake runners). I dunno about your ECU tuning, but based on 4.6L DOHC ford builds that I've seen with turbos, about 15* of timing should be about right. That's lower than the typical 20-25* timing that pushrod 302 ford guys normally run with boost. I'd say the VH would be VERY similar to the 4.6L. Then it's just a matter of matching fuel volume to air. If you have more than 20* of timing advance, I'd be a bit worried about damaging a piston and/or rings.
Modified by ScottJackson at 8:17 PM 10/9/2007

[qsiguy]

haven't had it cut out, just slight pinging. Engine feels strong, doesn't smoke, idle weird or anything. I doubt I did any damage just spewed a little oil.

I see two larger 3/8+ hoses going to the intake tubing near the throttle body. One on top/front the other out the bottom. Do both of these need to be addressed or just the top one. From what I can see Siju only put a catch can/breather on the top one. I have also seen VH installs in other vehicles where they ran the two hoses directly from the pass. side valve cover into a catch can. Any thoughts of what route I should take?

Any problem just venting the crankcase breather through a catch can then to atmosphere instead of going to the compressor intake? I'd rather not run another 3/8+ hose all the way to the back of the car. I've seen several setups that just vented the crankcase pressure.

In your description Scott, I'm not sure why you'd add a PCV valve. If the breather is reconnected to the compressor intake the breather line would never be getting compressed air like it is now. Can you elaborate?

[T45]

The FSM has a good diagram of the PCV system. If I recall correctly there are hoses from each valve cover going into the PCV valve located on the radiator fill neck on the engine. Then from there it goes to the intake. There is also a hose that connects between the valve covers I guess to equalize the pressure between the two. There are also 2 more hoses that run from the crankcase to the valve covers.

If you take off your oil cap while it's idling you shouldn't have a lot of air movement in the passage. If it's moving a lot of air then it's possible you have blow by.

The only reason that I suggest the compression check is that the pcv system will allow positive pressure from the crankcase to escape to the intake. If your hose popped off from the valve cover then you have too much pressure between the valve cover and the intake. The pcv valve should prevent positive pressure in the intake from making it's way to the crankcase. It's one of 2 things. Your pcv valve has failed and your turbo is pressurizing the crankcase, or you have rings that are allowing air to blow by them at such a rate that it is exceeding the flow rate of the pcv valve.

If you run a comp check and it's all good I would leave the 2 hoses from the crankcase to the valve covers, the hose between the valve covers and route either or both of the last 2 hoses to a catch can and then to the atmosphere. Otherwise if you put breathers on them you will probably have a nice oily film all over everything all the time.

[T45]

Actually now that I think about it....I'm not sure you should EVER run a pcv system on the intake on a psi engine. The pressure in the intake will always override the pressure in the crankcase. The pcv valve will always be closed under your intake pressure. Maybe before you were able to run 3 psi in the crankcase with no ill effects but at 5 psi the hose popped. Also be sure to check all other seals too.

[ScottJackson]

A PCV is supposed to work when you're not in boost. In a non boosted engine, it shuts at WOT. Both of the bigger hoses that attach to the main black intake tube (between air box and throttle body) need to be kept from seeing boost. You could either put a large one way check valve in each one or put a filter on the end of them and vent them to atmosphere. If these hoses are seeing boost, that's definately going to build up a lot of crankcase pressure while under boost. While it's ideal to have them routed to the compressor inlet for more effective crankcase evac., venting them to atmosphere should work fine too and would be the easiest solution with the rear mount turbo. If you only vent the top hose, you're going to blow air into the crankcase with the other tube (huge boost leak) and then vent it straight out with the other tube. You see, on the back top of the passenger side valve cover is where the bottom tube on the intake pipe connects. That's straight to crankcase (after it connects to the Y tube that feeds the idle air valve).
Modified by ScottJackson at 12:11 AM 10/10/2007

[qsiguy]

Ok, my other Q Already has the plenum off so I can inspect it and figure out the best way to do it.

Also, I didn't pop off a hose, just pushed out the dipstick and thats where the oil came out. Doesn't take much pressure to push out the dipstick.

[T45]

Ah, thanks SJ. Still learning about this whole boost thing. I've just been using common sense without having ever built a psi engine. lol

I thought I read somewhere that the hose popped off but I guess I mixed it up. My bad yo!

[qsiguy]

Dug into my other Q's plenum area and traced all the PCV and breather lines. The only one that I believe will require venting is the top one on the intake tube. The others are just crossover tubes and one goes to the PCV valve which I believe will close properly under boost but I'll need to do some more research to be sure.

Here's a pic of what Siju did on his turbo. His goes to a catchcan of sorts and then back to the air filter. I will probable do something similar but just vent to atmosphere.

[qsiguy]

In order to keep the vacuum intact for the crankcase while not in boost I thought up this system and think it would work. What do you guys think?

When the intake is under vacuum flow would go from crankcase through check valve into intake. When the intake has positive pressure (higher than crankcase pressure) flow would go from the crankcase through the check valve and out through the catch can to atmosphere. The intake in this diagram would be post turbo in my application.

[sijoko]

Careful, that could also mean some nasty ring blow-by. I would run a compression check on all cyl's before continuing.

I don't think the problem is with blowby but with boost entering the crankcase thru the PCV ventilation hose. The solution is to either divorce the PCV inlet or to move it to before the turbo.

[bullittandy]

I don't think the problem is with blowby but with boost entering the crankcase thru the PCV ventilation hose. The solution is to either divorce the PCV inlet or to move it to before the turbo.

I think you should try a trial separation first with counseling.

[ILuvNkdChx]

I can't say anything that hasn't already been said! GREAT JOB!

[qsiguy]

I can't say anything that hasn't already been said! GREAT JOB!

Thanks! One never gets tired of hearing that. Makes all the hard work worth while.

[Chuby]

Thanks! One never gets tired of hearing that. Makes all the hard work worth while.

You are mnaking me want to try to do a system similar to yours but using a pair of say 16g's mounted under the car. Trans is currently busted so the car is down anyway, might play around with it while it is down.

[qsiguy]

Go for it. It will be cool to see more people putting together custom turbo systems. Think outside the box and there are many options.

Realized today I have a slight problem. I need to extend the heat shield over the rear tail pipes. The OEM muffler shield is doing a good job over the turbo but over the tail pipes and the gap behind the bumper needs to be addressed. Too much heat is making its way behind the bumper and the paint on my bumper above the tail pipes is getting cooked. Not right where the tails pipes come through but on the top of the bumper so it's obviously hot air from the turbo getting through the gap and not just the heat from the pipes being too close. Some heat shield dynamat stuff or a sheet metal cover coated with some ceramic paint should do the trick. I didn't notice right away because my bumper was already a little jacked up in that area.

I got the wideband bung welded on the other day so now I just have to wire it up and I can get some readings.

[maxnix]

Longer tips and a heat shield?

Wouldn't want to be standing back there when you hit the throttle.

[qsiguy]

Forget this method or even just adding a check valve. I've been thinking about this and realized that this breather line feeds fresh air to the crankcase under normal driving to mix with crankcase vapors and blowby which then goes through the PCV valve. If I install this setup or even just a check valve it would render this breather useless. I was assuming that this line was primarily to vent the crankcase but it's not.

Here's what I need to do with it. I will wire up a vacuum or pressure switch to the vacuum line that will switch when I loose vacuum or achieve boost. That will switch an air solenoid installed inline on that breather tube that is normally open. When it closes it will block the boost pressure from entering the crankcase from the pressurized intake. Almost positive this is how I'll do it, I will post details and a diagram when it's done.

[Magnum PI]

awesome setup and writeup. I would send it to Nissan and let them know that the Q was a great car and they should try to develop a car that is true to the original.

[qsiguy]

very cool indeed but a few points...1) pressure check the charge pipe, the welds on your exhaust and charge piping look porous.2)get a wideband asap...narrowband is a complete joke.3)you need to do a maptrace if possible and back timing off, 46* is alot of timing even with ~4psi you idealy need an egt gauge to make sure you're not roasting your pistons.

keep up the good work, if you need help constructing a map lmk.

I wanted to update my response to this post. I originally said that the version of ECUTalk I was using was +15* off on timing. It is actually +35* off. The new version of ECUTalk, v 1.3.3 Bata 4, has a correction option for US spec to adjust -35* of timing on the gauge. I haven't tried it yet but will be shortly.