450/400's

907DAVE · Jun 21, 2012

Nice Post, Tim!

Both gates are 45mm. Just to clear things up I changed the spring in the secondary gate, not the primary. When I had the gate off I looked at the shaft and there was no evidence of it moving, it was caked in soot. While the spring was out I checked to see if it moved freely and it did. So I decided to drop down to the "8" and not use the "10" I had originally planned because of that.

I dont feel I am over driving the atmo turbo as it stays at a perfect 1:1 ratio, but total BP's are still a little high.

TARM · Jun 21, 2012

OK that makes much more sense.

I was not sure how you were computing you ratios hence all the work above. I have noticed many people just subtract primary turbo boost from total boost and then do a standard PR formula to get PR and this is wrong.

So you made the spring change on the secondary 66mm Comps gate. It was its boost that showed no change then not the primary turbos? So you have the secondary gate opening at a lower drive pressure and yet boost pressure did not change? There was no change to any of the boost levels ? Then it sounds like that size gate on that size turbine housing wheel size running at that low of a drive pressure is just too low. This is still the same exact issue just the gate that is past its limit has changed. You still IMO for a 50psi total boost have too little boost and drive pressure going thru that secondary turbo. That boost ratio is still, based on maps I could find for 66mm size turbos, not that good. I personally would really look at lowering the boost of the primary and upping the boost of the secondary. Still keep you at 50psi if that is what the goal is. Drop the Primary to a PR of 2.1 16 psi down from 25psi PR 2.7. That will allow you to flow more thru the Secondary and get it to a more efficient point in the map and will also get you back into a effective duty cycle for the secondary wg which it is not at the lower rate. This also still should keep the primary turbo in a 1:1 efficiency range as well. So I would flip flop what you were doing. See what spring it will take to get you to 16 psi boost.

Why not go ahead and drop springs in the WG that gives you the min control: 15 secondary 8-10 primary gates. Plumb in both WGs top and bottom ports with boost. You get some balanced pressure on the valve which is suppose to help stabilize it from what I have read and then use a regulator on the top port to adjust gate opening pressure. Then you can easily play with PR and total boost drive:boost ratios without having to open up the WG and do spring swaps and wait and see. I personally would much rather just turn a couple knobs or levels than break open the gates.

907DAVE · Jun 23, 2012

Since I am a stubborn SOB sometimes, I dropped that secondary spring down to a 5 psi spring.....and back pressure dropped down into the 1:1 range. I did not get a chance to open her up, but it definitely dropped back pressure.

My guess is TN has their own way of rating their springs.

TARM · Jun 23, 2012

That sure seems weird. Sounds like something was stuck or not right. After all if you go from 15 to 8 and see nothing but then go to 5 and see a drop that just does not add up. Maybe something about the springs not letting the gate open fully. Then whatever you did on that final change did. But what did boost go to? I mean it was already low.

907DAVE · Jun 23, 2012

The odd thing about those TN gates is they want you to plumb you boost reference into the bottom port of the gate, nothing mentioned about using boost reference to help hod it shut. Also, the size of the diaphragm is almost triple the size of the valve itself. This almost makes me think when they say 15psi spring, that's the spring needed to lift the valve WITH 15psi applied to the bottom port.

Dunno, I just wanted to get to a point to where the spring pressure alone was not enough to keep the gate closed.

Boost is low?

I run the truck on the street along side vehicles that include passengers, I do not drive like a jackass. 50psi is what I would see getting up to speed to merge into traffic, etc. I will save the smoke and WOT runs for the track.

Ahh *** it, maybe tomorrow I will do a boosted launch while hauling a full load of lumber for my house.

907DAVE · Jun 25, 2012

Minor setback.

YouTube Video

FORD7.3 · Jun 25, 2012

907DAVE said:
Minor setback.

YouTube Video

that thing steam powered????

907DAVE · Jun 25, 2012

I think I can tune it out...lol.

FORD7.3 · Jun 25, 2012

907DAVE said:
I think I can tune it out...lol.

more timing!!!!

907DAVE · Jun 25, 2012

bluedge8 · Jun 25, 2012

whats your guess, broken nozzle?

Big Bore · Jun 25, 2012

Oops, bummer Dave. Keep us posted. Was wondering why you weren't posting in tuning thread.

Derek@Vision Diesel · Jun 25, 2012

Looks like a nozzle to me! 400% strikes again....

bummer buddy, you had that thing running so clean too!

Big Bore · Jun 25, 2012

I'm really starting to believe a 300% nozzle would be a stronger more reliable alternative for a DD/street truck, giving us more fuel flow over the 200% without weakening the nozzle, and also making tuning a little bit easier. With the numbers we are seeing from 200% nozzles, a 300% should really be the ticket. Its too bad that nozzle size isn't more common.

907DAVE · Jun 25, 2012

Yeah, once I get the truck to the shop injectors are coming out. Sorry, I have been super busy trying to get my house framed in. The truck turned into a fog machine late last night after a easy ride to the store, lol.

Derek@Vision Diesel · Jun 25, 2012

Big Bore said:
I'm really starting to believe a 300% nozzle would be a stronger more reliable alternative for a DD/street truck, giving us more fuel flow over the 200% without weakening the nozzle, and also making tuning a little bit easier. With the numbers we are seeing from 200% nozzles, a 300% should really be the ticket. Its too bad that nozzle size isn't more common.

Even a 300% is fairly large if you look at one up close, strength and reliability with the 200% is where its at. I don't think I would run something larger that was going to be driven thousands of miles a year, but that is soley because of the fear of cracking a nozzle. Tuning and streetability arent the issue at all