wastegating facts

I have tried 62/.70, 62.80, 64/.70, 64/.80, 66/.70, 66/.80 all with 65 turbine and a 71 turbine. All with the same results. Any thoughts?
 
Red Stroke said:
Ok so if we are asking questions, I have a S362 and a S480, the 62 has a dual internal = to 40mm, I have an external 50mm gate bypassing both chargers. I will tune the 40mm for street driving with no drugs, then use the 50mm external for the drugs. I have 13mm worth of fuel and over 500hp of nitrous for the Dyno. For the street I am expecting 75 total PSI total with 35 to 40 psi from the 480. For the dyno I am going to gate fast with the 50mm to save the chargers. I am shooting for over 1300 hp.

What am I missing? Comments?
Twins011.jpg

Twins010.jpg

Twins004.jpg
Click to expand...



If it were me, I would have gone with a 88mm bottom turbo, keep it under 35 psi, and use a 64mm second stage to bump it to at least 85 psi....and reduce the nitrous shot to 200 hp
 
Glenn that was funny!

Mr. Diesel Freak

Thanks, so you are saying with that setup, it would be 1100 on fuel?

What do you think my huffers are capable of? You think I have enough gate for the bottle's?

I didn't want to go over 62mm and 80mm because I am going to try and street this. Also I have a custom 90 deg outlet cover on the 480 so I have to stick with that for a while.

I am just a plastics engineer playing with steel so I don't know anything!!
 
lol, there are some cool plastics out there...some actually hold up to some real abuse!!!

1100 on fuel...well, I am a 24 valve guy, so I dont know about that.

I just like using air vs. drugs...it's cheaper.

Since you are wanting to street the engine, then stick with the original setup. If you cant keep things from getting out of control, put a NewGen gate on the 480
 
Bponci said:
I have tried 62/.70, 62.80, 64/.70, 64/.80, 66/.70, 66/.80 all with 65 turbine and a 71 turbine. All with the same results. Any thoughts?
Click to expand...

All with the same results when running them as a secondary charger?
 
Sorry Brad....answered it myself when I went back and read your posts again.....your saying that issue is there regardless of what secondary you use.
 
carfichris said:
Sorry Brad....answered it myself when I went back and read your posts again.....your saying that issue is there regardless of what secondary you use.
Click to expand...

hmmm could be the wastgates are too small...or the piping to and from the wastagetes are too small
 
Diesel Freak said:
hmmm could be the wastgates are too small...or the piping to and from the wastagetes are too small
Click to expand...

Not likely on the secondary. He is running the primary too hard but his secondary gate doesn't seem to change things enough, even when bolted closed. A gate on the primary would lower the cold pipe boost but still wont solve his problem. Unless he has WG problems with the secondary there is no reason (well logical reason anyway) it shouldn't make a lot of boost with the secondary when the gate is held closed. He has run several different secondaries though so the problematic WG isn't likely.
 
RED STROKE.

Your problem was obviously compressor wheel over speed, of course whenever you run a single turbocharger at high boost levels you risk this happening. The max suggested wheel speed for endurance is 540 meters per second at the outside diameter of the wheel
Higher wheel speeds are allowed on hardened (hipped) and billet machined wheels. The turbine has a max operating speed of about 520 ft per second but the turbine is smaller in diameter. To calculate the wheel speed you need to assess our maximum flow and boost then look at your compressor map for the speed at that flow and boost level. Then find the outside diameter of your compressor wheel in inches multiply it by 3.14 for circumference, then multiply it by that wheel speed divide by 60 then divide by 12 that will give you ft, per second, if it exceeds 1770 ft or 540meters per second you should look for a alternative compressor wheel.
 
Cooking it down for the simple guy

I've read this thread through and am still a little confused about the debate.
I followed it through the point that the faster the engine turns the more load on the compressor of the turbo.
If I understand correctly, the debate started with the statement that when the wastegate opens, especially too soon, the TIP pressure exceeds the compressor outlet pressure. i.e. the -dp. I don't deal with compressor maps every day so my understanding is limited so bear with me.

The wastegate controls the pressure ratio of the outlet to inlet of the compressor as long as it hasn't opened beyond its control range. Providing that I am still operating the compressor at a reasonably compressor ratio, I may sacrifice compressor efficiency as I increase the load (rpm) but I shouldn't end up with a higher TIP than compressor outlet pressure. Nor would I end up at a negative pressure as the wastegate would close, driving the compressor harder to increase the pressure ratio back to its setpoint.

As far as actual TIP pressures, opening the waste gate should reduce the rate of increase of TIP as the engine RPM increases. The model of this in my head is having a resistor in parallel with a potentiometer. The wastegate being the potentiometer. The sum of the parrallel resistance is less than either of the individual resitances.

In my truck, I have enlarged the waste gate passage on my primary to reduce the drive pressure seen by the engine at high Hp and RPM's. The intention is to shift the restriction down to the secondary turbo. I hope that my understanding isn't all screwed up. (please note I did not say anything about what pressure the gate will be set at). I don't have any maps of my primary turbo at higher inlet pressures.

Please help me understand if I am wrong.
 
I think what he is trying to say is with nitrous it brings the power on early creating massive amounts of torque and that is what will kill the rods. Fuel only power tends to come on later in the powerband because of the turbo sizes required to make the same hp. So it's not so hard on the rods. The torque is what breaks most of the stuff in or on our trucks.
 
Exactly Nathan. I sheared the stock main shaft in my transmission last year with the same size nitrous jets that I ran all this year. The difference was that I delayed the second stage by 750 milliseconds this year which moved the spray up in the RPM range. Not broken shafts this year and they looked brand new when they came out.
 
You must log in or register to reply here.
Back
Top