Anyone on here spraying nitrous with over 100 lbs of boost ?

VaOutlaw said:
Since the gate dumps into the hot pipe on my primary my primary boost should go up. Plan on testing at the track this Thursday. Also plan on spraying it now too.
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Not what I have seen, drive may go down, but the Primary/bottom/atmosphere charge is seeing the same amout on the turbine wether it's gated around the top charger or not.
 
IdahoRob said:
Not what I have seen, drive may go down, but the Primary/bottom/atmosphere charge is seeing the same amout on the turbine wether it's gated around the top charger or not.
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We have seen the opposite, the more we gate around the top charger, the more boost the primary makes, and the less over all boost the system makes. This is part of the reason we are going to bigger turbines this off season, they obviously seem to be a restriction in our setup.
 
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IdahoRob said:
wow, must be a hell of a charger. Are you guys wastegating around your high pressure after spoolup as the numbers show your secondary is making no boost at those figures.
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Yeah it has been a good charger, it made the whole season no refreshing, it will be up for sale at some point this off season.

Pretty close the secondary does still add some compression, but we continued to make power the more we gated it so we just kept going until we hit the line of spooling vs power.
 
VaOutlaw said:
Playing with the gate tonight I was able to lower my total boost pressure to below 80 . Since the gate dumps into the hot pipe on my primary my primary boost should go up. Plan on testing at the track this Thursday. Also plan on spraying it now too.
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Good luck, looking forward to hearing your results.
 
dvst8r said:
Pretty close the secondary does still add some compression, but we continued to make power the more we gated it so we just kept going until we hit the line of spooling vs power.
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Interesting, when I did that the drive and egt went up. I went the other way and kept the primary in the 40psi range and much better on my set-up. I'm now playing with turbine housing on both chargers. 4 years later and still tweaking, does it ever stop?
 
IdahoRob said:
Interesting, when I did that the drive and egt went up. I went the other way and kept the primary in the 40psi range and much better on my set-up. I'm now playing with turbine housing on both chargers. 4 years later and still tweaking, does it ever stop?
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No. Because technology never stops ;)
 
IdahoRob said:
Interesting, when I did that the drive and egt went up. I went the other way and kept the primary in the 40psi range and much better on my set-up. I'm now playing with turbine housing on both chargers. 4 years later and still tweaking, does it ever stop?
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I wonder if this has to do with the differences of the rpm ranges (realistically we only have fuel until ~3500rpm) we run in. As I notice if we miss a shift and the rpm has a chance to go right to the limiter our drive is substantially higher then normal. Your setup obviously has the capacity to turn at least 50% faster, that is a lot of extra flow.

That is the beauty of heads up racing, there is always something to improve upon. We are only limited by our funding and our imagination.
 
Good point, My drive is equal to total boost at lower rpm, but really climbs in the upper rpm ranges for sure. I have a datalogger that graph's TB, PB, DP, EGTs, really helps with figuring out each change and how those changes affect the truck. Mate those with what tune was run, D/A, and the MPH of the run and helps make the correct decisions.
 
In my experience, it just hits a rpm point based upon turbine flow where it starts to shoot up, and the only way around it is through wastegating. On my 95 with the gates closed (and at about 600rwhp) it was about 2,600rpm. Without wastegating, the drive pressure shot up from 72psi to 99psi, and boost only went from 57psi to 61psi.
 
Definitely more about flow than boost. For example I'm 1-1 up to 70psi, yet I'm also 2-1 at 50psi. If you think about it a bit you'll see how.
 
dvst8r said:
It depends on what gear we are in, and if we are spraying, and how hard we are spraying. Typically somewhere over 3000rpm though.
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Thanks, here is another question if you don't mind.

You have said how your boost dropped after the install of a high flowing head. Did this affect the rpm where Drive overcomes boost? Or did drive always pass it at around 3000 rpm?
 
JQmile said:
In my experience, it just hits a rpm point based upon turbine flow where it starts to shoot up, and the only way around it is through wastegating. On my 95 with the gates closed (and at about 600rwhp) it was about 2,600rpm. Without wastegating, the drive pressure shot up from 72psi to 99psi, and boost only went from 57psi to 61psi.
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So did it make more power with the wastegates open or closed, did in fact the drive ratio have an effect on power production your truck?
 
gs1000 said:
Thanks, here is another question if you don't mind.

You have said how your boost dropped after the install of a high flowing head. Did this affect the rpm where Drive overcomes boost? Or did drive always pass it at around 3000 rpm?
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No it used to be earlier, but then again boost was higher earlier too. So hard to compare straight apples to apples.
 
gs1000 said:
So did it make more power with the wastegates open or closed, did in fact the drive ratio have an effect on power production your truck?
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No, not a huge difference in power, just made the driver sweat a little more about the turbos ;)

I know on pulling tractors that run 2500hp, you can see 200hp or more based upon drive pressure changes, but that same 10% on a 800hp motor is about 80hp, if you know what I mean. And, in some cases (such as when you have to pedal it at the dragstrip) having a little extra drive pressure and spoolability is actually beneficial.
 
WOP's old race trucks were always making 110-125psi boost with quite a bit of nitrous running through them without issue. Just gotta make sure that drive pressure stays down, so make sure there is enough wastegate to get around the high pressure and keep the low pressure in it's map.
 
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