gt42

Rollin Coal said:
the 4202 goes good on the bigger motor. the ball bearing must be nice also.

do you get any surge with the 1.01 housing?
Click to expand...

No surging, I need to get some more tunning done, Spools fast but need to get the PW bumped up some more in the upper rpms she likes 4,500+,On the dyno it made 39 psi of the 50 to 55 I see on the street and looked like a gasser once it was at 39 on the dyno made 613.Combo is good for in the 800+ rwhp.I just suck at Efi Live.:bang
 
ripmf666 said:
No surging, I need to get some more tunning done, Spools fast but need to get the PW bumped up some more in the upper rpms she likes 4,500+,On the dyno it made 39 psi of the 50 to 55 I see on the street and looked like a gasser once it was at 39 on the dyno made 613.Combo is good for in the 800+ rwhp.I just suck at Efi Live.:bang
Click to expand...

yeah, im working on getting my truck to the 4200-4500 rpm area.

i make about 40 on the street with fuel cutting at 3200
 
98andahalf said:
you could get it to spool quicker if it is a divided (twin scroll) exhaust housing by using an actuator operated block-off door on one of the ports. It closes off one of the ports so it turns a 26cm exhaust housing into something like a 13cm exhaust housing and then once you get past a certain psi, the door opens to relieve excess back pressure and help the turbo flow much more in the high boost levels
36433.jpg
Click to expand...

I can't get the idea of this device off my mind. Right now only in just the consideration phase. I currently have an ED spacer plate for my ED gate. If I was to open the dividing portion up, after consulting ED ofcourse, I'd have the manifold, the ed plate, then this device. Now, that being said with a divided t4 inlet turbine housing on my s468 is there still benefit with this piece or does the turbine housing inlet need to be undivided for this to work?
 
We have something similar in the works Nick. I have it sitting on my desk right now.
 
mondtster said:
In my experience, a gasoline turbo motor will typically generate hotter exhaust temps than a diesel motor will. The max EGT number that we would try to stay under with the gas stuff was always ~1550 degrees F. You could easily peg a 2000 degree pyro with a car that wasn't set up right. Cruise temps were typically in the 1500 degree range as well.
Click to expand...


While you try to stay under 1550, my truck sees well over 1900 degrees very often.
 
zstroken said:
While you try to stay under 1550, my truck sees well over 1900 degrees very often.
Click to expand...

For sustained periods of time?

The sustained exhaust temps will be much higher in a gasoline turbo motor than they will be in a diesel motor.

For instance, cruising in my truck on the highway I may see exhaust temps 600-800 degrees F range consistently. Any of the gasoline turbo cars I have owned typically will cruise at temps between 1300 to 1500 degrees.

Getting up to 1900 degrees for a short period of time really isn't an issue regardless of what you're working on IMHO.
 
Well when you consider the melting point of metal, and the slow burn of diesel, dumping enough fuel in at high rpm, some of that diesel is still burning on the way out. I don't have tons of 4 stroke gas experience, but I have seen several burnt turbines on diesels, is that common on gassers?
 
zstroken said:
Well when you consider the melting point of metal, and the slow burn of diesel, dumping enough fuel in at high rpm, some of that diesel is still burning on the way out. I don't have tons of 4 stroke gas experience, but I have seen several burnt turbines on diesels, is that common on gassers?
Click to expand...

I have a lot more experience with gas turbo motors than diesels.

I suppose that it would be possible to burn a turbine wheel on a gasser, but I think the ignition timing would have to be extremely retarded before that would happen. Personally, I think you would have other problems showing up before a turbo would die in that fashion.

It would seem to me that if you're having that much fuel still burning on the way out with a diesel that it is just a waste anyway. Maybe there's something I don't understand about diesel injection?
 
I think cams designed to spool the turbos up sooner by opening the exhaust valve early and allowing pressure that should be pushing on the piston to push on the turbine wheel to burn in the exhaust cause high EGTs and too late injected fuel will cause high EGTs,doing this allows extra thermal energy to keep the charger lit. I could see someone having normal combustion camber temps and really high exhaust temps based on some tuning problems like above.
 
mondtster said:
I have a lot more experience with gas turbo motors than diesels.

I suppose that it would be possible to burn a turbine wheel on a gasser, but I think the ignition timing would have to be extremely retarded before that would happen. Personally, I think you would have other problems showing up before a turbo would die in that fashion.

It would seem to me that if you're having that much fuel still burning on the way out with a diesel that it is just a waste anyway. Maybe there's something I don't understand about diesel injection?
Click to expand...


I don't have much experience with the gasser stuff, but turbine wheels on the diesels seem to melt in applications.
 
mondtster said:
Maybe there's something I don't understand about diesel injection?
Click to expand...

Well for one I think diesel injection has much more quantity then gas when it comes to ATDC. I think most of the injection in a gas motor happens BTDC and is largely done ATDC. This being said at wot the diesel, atleast performance diesels like we know, may result in very high temp exposure to exhaust parts. I think it's Garret turbine wheels that have been said to melt in diesel applications.

But then again I was always told that egt's from gas applications are generally higher. :what:
 
NickTF said:
Well for one I think diesel injection has much more quantity then gas when it comes to ATDC. I think most of the injection in a gas motor happens BTDC and is largely done ATDC. This being said at wot the diesel, atleast performance diesels like we know, may result in very high temp exposure to exhaust parts. I think it's Garret turbine wheels that have been said to melt in diesel applications.
Click to expand...

I wouldn't get hung up on the injection event timing on a gasoline powered motor. It really means nothing. 80% injector duty cycle is common (some people even run 100%) so the injector stays open through most of the cycle. The fuel just sits on the back of the valve waiting for the intake valve(s) to open and let the air/fuel mixture in the chamber.

Ignition timing on the other hand can be critical. Too much advance and you can crack a piston, blow a headgasket, crack a block, puke a rod, etc. Too little and you can burn valves, hurt turbos, melt cats, etc. Ignition timing would be more closely related to diesel injection timing if you're looking for a correlation.

Maybe someone will come in here and explain this to me a bit better, but I see no benefit from having a bunch of fuel being injected late in the cycle and having it just go out the exhaust. It just seems like a waste of fuel to me. You could obviously start the injection event earlier to move the end of the injection event up as well, but you can only go so far in that direction too. I would think delivery valves and/or injector pop pressure might be the next place to start looking at that point.

NickTF said:
But then again I was always told that egt's from gas applications are generally higher. :what:
Click to expand...

That was my original point. I don't see how anybody could claim that the average exhaust temps are going to be higher on a diesel when it is clearly the other way around.
 
I understand and good reply. I used to have a small business doing some ls1 edit based tuning on gm's ls series motors and we never moved injecting timing, only spark timingand injection quantity along with some other paramters.

At this point i'm thinking rpms are the reason gas motors have higher EGTs at cruise.

Diesel motors have to have fuel injected later in the cylcle so far as I understand it. Much more energy is transfered to the piston during it's travel ATDC then a gas motor, one of the reasons they produce so much more torque then a gas motor does. Now, that being said those of us trying to make more power increase the timing BTDC to account for the quicker combustion required at higher rpms, but you still can't get totally away from the fuel injected ATDC for a diesel to work, atleast I wouldn't think so in a street driven diesel.

I think it's totally relevant given, as you hinted att via later spark timing in gas motors, a later burn produces higher exhaust gas temperatures which in turn is harder on exhaust parts.

Gas motors may have higher on average cruising temps possibly based on rpms, but it's possible max effort diesel apps have higher peak EGTs based on the later burn characteristics of the diesel process.

This is all just my guess based of very limited facts.
 
I don't want to get on here and step on any toes until I talk to someone about sponcership of this site. We do have actuators for our Quick Spool Flanges now, with alot more range.
 
blacksmoke83 said:
damn !! I ran a powermax Stg 3 last summer which is a Gt 37 with a big exaust housing and between the moment I floor it and the moment it light up, I had time for a beer !!! Lots of air flow but, no drivability. People were looking at me just like I was an ALIEN cause of the 5 gallon of black unburnt fuel behind me !

I hope that a Gt 42 spool faster then my Gt 37 ! Let me know
Click to expand...
My GT3788R spools fast as hell! I can get over 40 PSI of boost at 1500 RPM. Did you not have the mods to support it?
 
Mopar Man said:
Let us know what id does on the dyno. Im wanting to get a GT4202R (B.B.) to put under my GT3788R to make a true B.B. compound kit
Click to expand...

That's the setup I started with... except the bottom was a gt4208r. It really rocks.

I don't get the earlier statement about a stage 3 not lighting... something definitely wrong there. Hell, even now that I am using a gt4094r on top with a .99 A/R, it still spools as fast as a HE351e.
 
You must log in or register to reply here.
Back
Top