My l18 turbo blow through 620 finally running!!!!

[620Turbo4X4]

Awesome… Glad you got it running!

 

You should post some photos. I'm sure there are a more than a few of us on here that would like to see it.

 

You inter-cooled it, right? There wouldn't be a lot of benefit by water injection on a inter-cooled engine. Water was used mostly in draw through setups that can't be inter-cooled. The idea being that if  water is added before the turbo, it will absorb some of the heat created by the turbo by the conversion of water to steam. Not a good idea if using a intercooler because the steam will condense and fill up your  inter-cooler with water.

 

Are you still using the stock l18 8" clutch? With 8 lbs. of boost on a l18 it should be slipping... If your afr's are correct, you may need to optimize your ignition timing better???

[jwerty1]

Yes it is intercooled.  The water injection is to be before the carb on this one (blow through) and after the intercooler, mostly to be used as anti-detonant.  From what I've read (a lot) water injection's benefits are best when closest to the combustion chamber and when used under boost via a boost pressure switch the timing can stay the same with out retarding it.  Therefore, a water injection setup, built with stuff I have laying around, will take place of a 400 dollar boost timing master.  The stock clutch seems good for now.  No slippage yet.  I had the motor/trans out about a year agoish.  The motor is still new at about 68k (original miles).  When I did have it out I replaced the clutch disc and throwout.  Pressure plate and what not all seem good.  We will see.  If it starts slipping I will just have to find a five speed.  By the way, I took my wife on a ride last night and she likes it :thumbup: .  She did say " Why does it sound like its going to fall apart?" She was referring to the noise made by the blowoff valve, so I explained that to her.  My 5year old boy thinks it is a rocket ship now. :thumbup:

[jwerty1]

My truck before the turbo

 

after the turbo

 

engine shot

 

turbo

 

carb hat and such

 

tailpipe(used to be a dodge diesel downpipe)

[jwerty1]

 

[datzenmike]

You already have a post on this. How about we keep this one?

[jwerty1]

that's fine, just excited

[datzenmike]

I can tell...

[Dawa]

now we need photos of your set up. 

[jwerty1]

check the engine forum, turbo l question

[datzenmike]

Rather than directing people to two L turbo posts why don't we combine the other with this one? All pictures, info, questions in one place. This would become your turbo build thread.... http://community.ratsun.net/topic/57762-my-l18-turbo-blow-through-620-finally-running/

[jwerty1]

deal

[datzenmike]

.... and done.

[MantisX620]

Did you change the bushings in the turbo for blow through? I heard they had to be carbon?

[datzenmike]

I think that may be for suck through turbos. When revved up and the throttle is slammed closed the turbo produces close to a vacuum between it and the carb ahead of it. This can suck oil through the seal.

[jwerty1]

you only need to do that for suck through.  This is blow through, not requiring anything special for the turbo

[MantisX620]

Ahh ok. Sounds good. Would like to see the manifold and the acceleration! I can use that to judge if I still want to do it or if ill putt around on it as is and keep it reliable.

[banzai510(hainz)]

You have to retard the ignition when the boost comes ON??????????

[jwerty1]

have to get a pic of the manifold, don't have any from when off the truck.  basically cut manifold right below flanges, weld in a straight piece across them then to a flange.  I have not retarded the timing so far, seems fine, haven't heard any pinging.

[620Turbo4X4]

Good work!! Sounds Great, bit more fine tuning. I would avoid using water to prevent knock. that would be very unreliable. Retarding the timing as boost increases is the correct way to do it. You really don't want to spray the water in before the carb as the water getting inside the float bowl will cause random lean conditions, and a whole list of problems….

 

I wouldn't spend $400 for a new Boost timing master either…If you have, or know someone with a eBay account, look for a BTM there. They go for around $50-$100 used..

 

Your exhaust sounds pretty loud. Pre-ignition/detonation is relatively hard to hear even with a quiet exhaust. You'll have a really hard time hearing the engine knocking with loud exhaust… Thats what killed my old turbo truck.. Having a ignition system with a knock sensor would be a good idea. Timing on turbo engines is very important for making good power and reliability. There were a coulpe of the electromotive TEC 2 standalone systems that recently sold for between $300-400 on ebay. That would be the cats pajamas for a rock solid ignition system. You could use it as just a ignition system for now, then wire up injectors later if you decide to go efi. A throttle body injection system would be easy to do and get rid of all the carb problems. You already have the wideband gauge and it should have a +5v output for efi systems. That'll make tuning a cinch! The only real hard part is the trigger wheel that gets mounted directly to the front pulley. 

 

Here's a photo of the trigger wheel setup for my TEC system...

 

 

 

 

The sensor mount can be made from a block of aluminum…I got a little carried away with mine... mounting the trigger wheel should be done by a machinist as is does need to be as perfect as possible to take advantage of the Tec's 1/4 degree ignition accuracy. Programming can be done with any old crummy laptop pc running windows 98 or better as long as it has a com port, so it's not like you would have to spend a bunch on that... ($50???)

 

Really nice looking truck!!! Wouldn't go cranking the boost up till you get it all dialed in though... Don't want to be blowing head gaskets. You'll know when your getting there when the little L18 clutch starts slipping... When you look for a 5-speed avoid the dog leg trans, and try to find a L20b flywheel too.. larger diameter disk…..

 

:thumbup:

[datzenmike]

You have to retard the ignition when the boost comes ON??????????

.

The more gas and air you ram in there the more you will raise the compression. The flame will jump from molecule to molecule faster than lower compression. The timing would then need to be reduced more and more for the shorter burn time.

[jwerty1]

hooked up the water injection, everything seems good for now.  This will be the extent of my mod's for a while.  I will enjoy all this and save up to build a backup motor and 5 speed.  Took a drive with a  chassis  ear attached to the block today to listen for detonation.  Honestly I couldn't make out anything other than the noisy L valvetrain.  And when I thought it sounded reminiscent of pinging it was under very light accel and the afr's were about 13.  I really don't think it was detonation, or my motor would be toast, plus it wasn't under boost, just real light accel.  Put in 1 range colder ngk's today to see how they work out.  I wasn't having any issues with the stock b6es plugs, but I figured colder would be better.

[datzenmike]

What would be wrong with the water injected after the carb?

[jwerty1]

Nothing, just easier to mount in the intake piping, and its pretty close to the carb so I'll still get the benefits in the combustion chamber

[southern620]

Any pics of how you stuffed that intercooler behind the valence?

[jwerty1]

I'll get you one, basically I cut out some of the front valance for more airflow, and removed the lower screws on the side so I could bend the valence out some.  Guy stopped me at lowes the other day and said nice Datsun.  I was like thanks, I just turbo'd it.  He was like I could tell.  Is that an sr20 in there?  I was like no, its a friggin L motor baby!