Blow off valve at Light Throttle = vacuum leak?ear

[fo0manchu]

I just finished my turbo setup on my datsun 510 wagon and have been trying to get all the kinks and quirks out of it. I sealed up all the vacuum leaks with making a boost leak detector.

My air fuel blips really lean on light throttles in any gear. Especially at cruising speeds on the freeways. It goes lean and comes right back. After searching for awhile and messing with the safc, I found that my BOV is not closing fully when the throttle plate opens slightly. This is actually causing unmetered air to be sucked in. (I put some paper close to the opening of the valve to test it, and watched the paper get sucked to the opening as I reved) So I am guessing this is causing my lean spots. Just like a big ol' vacuum leak.

I have a adjustable stock volvo type valve. It stays open at idle, then closes when the vacuum pressure drops enough. I could recirculate it the way it was designed to be, but I like the cool sounds the car makes.

My question is, is this how all stock piston style valves work?I was thinking about getting a different BOV, but if they all do the same thing then it would be a waste of money.

[fo0manchu]

Here's another thing I thought of.I have my BOV, fpr, and electronic boost gauge hooked up to one vacuum source. Does this make that big of a difference?

I was reading a bit and some people say to hook up the fpr and bov to its own source.

[WDRacing]

If you use a bypass valve you won't have stalling issues or vacuum leak issues. Open atmosphere BOV's cause more problems then Chinese knock off turbo's...lol.

When air gets metered by the MAF, then gets released you create an over rich condition. Or in your case, it doesn't close all the way creating a lean condition.

Route that dude back to the intake

WD

[neverlift]

IDK it may be worth the issues, that is a sexy mutha f***er he has. I absolutely LOVED mine, such crisp/sharp sound. I like my greddy but the volvo is more.... vocal.

Have you tried blow through I know I preach it like a pastor and all, but the benefits are tremendous. obviously my personally opinion.

all valve type bov work this way, sorry.

[fo0manchu]

hahha.. yah i do like that sound. But I might have to re-route the sucker. In 5th going about 80(which is pretty close to boosting, i have like a couple hg's of vacuum) I barely touch the throttle a bit more it starts to boost and the afr's goes past 17. It comes back down to 11ish, but dang kinda scares me. I figure that would be all it takes on a hot day and bad gas to go kablooey.

The way my turbo and side mount is set up, the maf would be on the hot side. Don't know how well that would work.Here's an older pic of my setup. I have since made a new intake pipe with a better bend going to the maf and the valve cover breather is routed back into the the preturbo pipe.

[neverlift]

thats a pretty sick little setup you got going.

That side mount though is looking more like a SMIH being under the hood and all. roflmao what turbo is that it looks like mine

yeah I would be careful 17:1 and boost = death.

IMHO with blow through you want the afm after the IC so it gets the coolest reading/most accurate going into the engine. Ever think about squirting that thing? not MS, water injection... It would probably do more for you than that sr sidemount under the hood.

[WDRacing]

Unless there is a vent directing air at the SMIC then you could just lose it all together and gain a few hundred rpm earlier boost. Eventually that thing is just gonna be heat soaked and totally ineffective.

A very small water jet would be a far better option then that SMIC setup. It doesn't take much water to drop the combustion temp 200*.

WD

[neverlift]

I concur my water injection location is cold to the touch after an hour of beating on and off the other night, the pipe was barely warm. And I think that was radiant heat from the engine/radiator.

it can be done for less than your IC cost probably.

[WDRacing]

cold to the touch after an hour of beating on and off the other night

Just wow dude...

[fo0manchu]

My original plan is to go water injection. But money inhibits that at the moment. I still need to duct the intercooler. The duct will be coming up from the front valence. And then hopefully i can get some old school hood louvers stamped in the hood.

I'll only be running up to 10lbs of boost. We'll see how long that lasts, or until I blow my motor. hahah Then rebuild and higher boost, here I come... yah!

But anyways, water inj sounds awesome. I remember doing research into that about 2-3years ago when I was only dreaming about going turbo.

My cold pipe is just welded aluminized steel right now, would i have to go stainless or alum to run water inj?

[fo0manchu]

turbo is just a garret t3, .63 exhaust housing .4something compressor. it was taken off an old school audi or mercedes that got in an accident after 100 miles of rebuild. Got it for cheapo $100... and works great!

[neverlift]

Dont be fooled by those fancy water injection kits. I spent a total of 33 dollars, my local yard gave me the rest for free. Got a washer tank from a buddy for free and it only improved the setup(no more gatoraide bottle lol) dual pumps now...

if I ever get a camera again I'll try to make a thread on the worlds cheapest water injection setup that works.

[fo0manchu]

hmmm... now you got me thinking. Where did you get your pump from?

[neverlift]

Well I picked the first pump I used up from an old volvo , I picked it cause it is a rather large pump(for a washer fluid pump lol), got home and cut it on and it was uber loud and moved some decent water.

Then not happy with the visual aspect of the gatoraide bottle and pump hanging out the side with a hose, I asked a couple friends if they had any old windshield washer tanks laying around, and it turned out my slide partner had one from an old z. This particular unit had twin pumps, so I wired them in together and separately to see which way moved more fluid. The dual moved more at higher pressure(figure it cant hurt lol). SO I quickly mounted the tank and wired it all in and what not.

The single pump was going fine I just plan to upgrade this to a dual stage so the flow/pressure wont hurt.

[Doya]

I'd love to do a water injection setup but I wouldn't have the slightest idea where to start.

[neverlift]

I actually have access to a camera atm, but not sure if I feel like a write up...

[Doya]

I actually have access to a camera atm, but not sure if I feel like a write up...

C'mon

[fo0manchu]

I heard of people using the window washer pump, but I also hear it leaks due to boost pressures. How is yours holding up? do you have a inline water solenoid as well? and do those pump put out enough pressure to mist the water? I'm assuming your using like some NOS nozzles.

I'm all for cheap and diy!