77 280z, Turbo the N/A motor with carbs?

[Tony D]

"I don't have an egt or iat guage either."

 

Read what I wrote, something about 'instrumenting that engine up and seeing what is really going on... Jetting fat will cover a bunch of maladies, it always has... It's not 'right' either. Put a WBO2 AFR gauge on there and start driving around to see where you're at and you will be amazed what you find. Having an EGT shot with a skin temperature gun during a dyno run and finding 850 on the turbine housing is not what I would call 'correct air-fuel management instrumentation'...most people agree that these days EGT is about the LEAST reliable 'quick check' of AFR or fueling. It gives you an 'idea' but really is not telling you much! EGT needs to be in the stream, near the valve to be useful. T I T and T O T are measures of work being done by the turbine, and not much else. They for sure aren't an "OK" of the car and it's AFR status. And like I said, a Dyno run is anomalous to running the car on the trailer for a drag strip weekend. If you aren't driving it daily, the 75% functional correctness may seem more like 100%!

 

Run around at 12:1 all the time and you won't have 'sneezes'...and you will get 12-17mpg. Jet the carb properly for AFR's like it should have and you start realizing the limitations of the controlled vacuum leak! Try getting 25+mpg out of a carbed turbo on an L-6 and you start realizing the limitations of the fueling choice pretty quickly. If I can get 28mpg on my N/A motor, why can't I get close to that on the Turbo Motor? Because the carb is a comprimise, you have to jet up more than N/A optimal to keep it from self detonation and death under boost. It's a fact of life, no way around it (unless perhaps you have Dellorto DHLA 45M's....)

 

But this is always the reply: "My carb runs fine"---and 40 years ago most people thought that as well. But as instrumentation makes it's way to home hobby-builders, eventually you will find how deluded you reall were!

 

My Thermoquad ran great on the old turbo Corvair, so what if it puffed a little black smoke now and again... If you don't hear a problem, does one exist?

 

Answer in some people's minds is "If they don't know about it, then no!" I do not ascribe to that theory. As much as you love your setups, don't delude yourself into buying your own lies to yourself. Instrumentation makes liars of us all eventually. But if you never set it up and check, you never find out what the REAL deal is inside the engine!

Edited May 11, 2010 by Tony D

[yetterben]

per Tony's request i put a piece of black tap over my wideband like a ses light lol. With a holley or any 4 barrel turbo setup it van be arranged so boost never builds on the primary side only secondary side. In fact it should be setup like this for good performance. With webers and such its a lot harder and the rewards are alot greater.

 

Bottom line and i think tony and i are on teh same page and for the 10 or so people that pm me weekly. Blow through is pretty much a novelty. It's not 100 percent reliable can it be borderline sure sure is it fine for the most part at wot sure sure. But do we drive wot all over the place nope. It can never ever ever be as a good as a cpu.

 

Downdraught is the lesser of the two evils maybe but also the lesser of the two power wise. Downdraught belong's on v plane engines. Tony has lots of experience with cartech corky bell trash as do i. Gave Carbs turbos a really bad name simply becasue people bought into the hype belived the ads. I have seen everything from the old cartech draw through all the way to the fancy dancy cartech air to water setup on a 13b. All of my cartech experience is on rotaries. It was all trash. Dont even get me started on the Pontiac 301 turbo setup.

Edited May 11, 2010 by yetterben

[280zex]

I do run wbo2. I get 12.9 afr at idle and cruze and pretty much every where. wot goes to 11.1 @ 8 psi @ 6.5k rpm. I can roll into the throttle or jam it. Never had tip-in issues or hickups or intake backfire/sneezes. I am curious how much temp difference between iat and ambiant air temps are. I have an air to water inercoler and its my first time using one.

[280zex]

Tony I was curious about turbine housing temps thats why I used the thermal laser. Never tried one before so I was a kid with a toy. It was kinda comic like. I was hitting everything with that laser.

[Tony D]

" I get 12.9 afr at idle and cruze and pretty much every where."

 

11.1---omy GAWD! Talk about RICH! No wonder you don't have an coughs, you are WAY down on power running that fat. Matter of fact, you are bordering on blowing sooty black smoke out the tailpipe. Terribly inefficient.

 

Like I said, run it rich and you will never see anything. At idle with EFI I am running 13.2, at 1500 I'm running closed-loop maximum of 14.7, if not closer to 15.3:1. By 2000 in and up to around 3000 if in negative territory below 75kpa, I'm running closer to 17:1 AFR.

 

Not a hiccup, sneeze, or cough. No surging. Hammerdown and the thing transitions to boost and my AFR goes to 12.2 instantly, up to around 4300 rpms where the fueling pulls back to around 13.8. The difference between my carbs at 5000 rpms and 12.3 AFR, and my EFI at 13.8 AFR is around 28HP, with a corresponding lengthening of the torque curve further up the RPM range.

 

Try to do THAT with a Carb. I tried for two years solid and countless dyno hours. Won't happen. Talked with the best in the business and even they said "Go to EFI".

 

When the transient popping at light cruise between 75 kpa and roughly 2psi of positive plenum pressure would NOT desist that was it, I took Corky's "Better" box off, realized I was better off with my home-made HKS replica, and decided to start buying parts for proper period correct EFI for my car. It took a decade before I found all the correct parts. While Ben may have a close approximation of the original Devil Z in his car, I have the engine parts to make the last Akio Build from the first movie... HKS Plenum, HKS ITB's... Oh, and some other goodies. In the interim I spent my time learning EFI by building my own megasquirt and going that route. Once you do it and drive it, you quickly ask yourself why you tolerated the irksome habits of the Carbs for as long as you did!

[yetterben]

Trust me i try to get Tony to come off of those Hks Itb's. Not gonna happen. My car is the closest thing on here to Akuma-zeto. Outside of two old crappy td06's. I have thought about going to the standard efi intake tony. I think i will looses power though if i switch over to the l6 efi intake. If i was offered 1,800 for my intake setup i would switch in a snap.

[Tony D]

I wouldn't go back to the EFI setup, I'd just convert what I had to use EFI, remove the chokes, and go. Everything exists to do that you just need injector bungs someplace, and a fuel rail...

[yetterben]

Forgot about a couple a people i know down south here in Wisconsin. They both run the same setups. Dave and Steve and there twins. Last i talked to these guys they where getting ready to drop lsx swaps in. From memory these are both 3.0 stroker's.

 

 

 

 

[turboHLS30]

Here is my triple mikuni turbo stup.

The Mikuni's are 40mm and the turbo is a T04b

[Tony D]

Nice compressor bypass valve...

 

I end my comments there.

[yetterben]

lol Corky "Retard" Bell vrrrmmmmmmm shift pop piss bang vrmmmmmm shift pop piss BOOM!

Edited May 14, 2010 by yetterben

[turboHLS30]

Double post on accident

 

 

Edited June 1, 2010 by turboHLS30