Vararam+200mph = ?
Thread Starter
Melting Slicks
Joined: Feb 2013
Posts: 2,034
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Vararam+200mph = ?
Hey guys, I'm building my car for the standing 1.5 mile magnum event this year, should be about 600whp and shooting for 200mph (although I know that is a stretch).
The car will be h/c/i m6 c5 with 150 shot of nitrous running race gas.
intake is currently a "Halltech t7 cobra" or something with the giant K&N filter.
Anyone else out here running standing mile events with a Vararam intake? Did you have the tuner add more fuel in the upper rpms to compensate for potentially more air flow at >170mph??
I am going to be winding 5th gear out pretty hard, on nitrous, for 1.5 miles straight and am afraid of blowing my engine up.
thanks!
The car will be h/c/i m6 c5 with 150 shot of nitrous running race gas.
intake is currently a "Halltech t7 cobra" or something with the giant K&N filter.
Anyone else out here running standing mile events with a Vararam intake? Did you have the tuner add more fuel in the upper rpms to compensate for potentially more air flow at >170mph??
I am going to be winding 5th gear out pretty hard, on nitrous, for 1.5 miles straight and am afraid of blowing my engine up.
thanks!
Last edited by neverstop; Mar 14, 2014 at 09:53 PM.
Thread Starter
Melting Slicks
Joined: Feb 2013
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Le Mans Master
Joined: Mar 2002
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From: PNW
If the system is open-loop and tuned on a dyno without ram-air considerations, then it will be lean on top with that much added ram-air pressure.
Thread Starter
Melting Slicks
Joined: Feb 2013
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The theoretical added ram-air pressure at 200 MPH (if Atm is at 70 deg F and 29.85 in-Hg = 1 Atm = 14.7 psi) is 0.70 psi. That's an additional 0.70/14.7 = 4.76% more pressure feeding the engine.
If the system is open-loop and tuned on a dyno without ram-air considerations, then it will be lean on top with that much added ram-air pressure.
If the system is open-loop and tuned on a dyno without ram-air considerations, then it will be lean on top with that much added ram-air pressure.
Would you mind posting the detailed math there? I'd like to use this in excel to help my tuner add the correct amount of fuel in the upper rpm band of 5th gear to get add the appropriate additional fuel from 160-200mph.
I'm guessing another way to do this would be to just run the nitrous fuel jet on my wet kit about 5% richer since I'll never be hitting 200mph off the bottle?
Of course even going a little lean at 6300 rpm on 150hp of nitrous would be a grenade engine = NOT fun at 200mph!
Last edited by neverstop; Mar 14, 2014 at 11:03 PM.
Le Mans Master
Joined: Mar 2002
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From: PNW
Speed (MPH) Ram-Air Press (PSI) Ram Pressure % Increase
0 - 0.00 - 0.00%
25 - 0.01 - 0.07%
50 - 0.04 - 0.30%
75 - 0.10 - 0.66%
100 - 0.17 - 1.18%
125 - 0.27 - 1.85%
150 - 0.39 - 2.66%
175 - 0.53 - 3.62%
180 - 0.56 - 3.83%
185 - 0.59 - 4.04%
190 - 0.63 - 4.26%
195 - 0.66 - 4.49%
200 - 0.69 - 4.73%
Thread Starter
Melting Slicks
Joined: Feb 2013
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AWESOME! thanks for doing that. I'm still working on how the tuning is going to work out, 600whp on stock bottom end is right on the ragged edge so I really need to make sure there isn't any detonation.
I'll call Vararam too and see if they have any customers who have done this before and let you all know how it goes.
I'll call Vararam too and see if they have any customers who have done this before and let you all know how it goes.
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Thread Starter
Melting Slicks
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Le Mans Master
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From: In the pit, trying to love someone.
Can you do that? Does the PCM have the ability to have fuel mapped differently for different gears?
Thread Starter
Melting Slicks
Joined: Feb 2013
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I am not quite sure but there are a few options here, I am thinking I could have the nitrous tune include an adjustment factor in the upper rpms, in effect tuning the car for 5th gear, but I really don't want this to get crazy complicated though so most likely I am thinking I'll just jet the nitrous wet kit about 5% too rich to compensate and accept lower hp at lower speeds/rpm or i'll just keep my halltech setup and scrap the vararam entirely. I'm going to call my tuner and vararam next week and make some decisions.
Melting Slicks
Joined: Jul 2005
Posts: 2,990
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From: Mt. Pleasant S.C.
not exactly sure but just to the sides of the nose of the car probably builds some air up at 150mph+ imo, either way it is likely better than the stock style intake I have now and I don't want to make this another Vararam argument but the performance advantages of the Vararam intake seem to me to be without question so hopefully I can make this work as 200mph in 1.5 miles is a stretch for my setup so I'll need every advantage I can get
Thread Starter
Melting Slicks
Joined: Feb 2013
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Not my point at all nor am I looking to start a vararam vs stock argument. My point is that you're doing math to hand to your programmer and I'm questioning whether or not that math is legit. If the airflow through those ducts reduces as the air flows over the car at higher speed then your math is out the window. I'd caution you on basing even part of your tune on a ram effect that may at some point actually decrease as your speed increases.
Do you have any reason to believe the vents right to the side of the nose of the car would not be a high pressure area? I guess I am running on the assuming the Vararam works and that air would be "building up" on the front and nose especially of the car, with the effects only increasing as the speed goes up.
Thread Starter
Melting Slicks
Joined: Feb 2013
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Melting Slicks
Joined: Jul 2005
Posts: 2,990
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From: Mt. Pleasant S.C.
good point, I see what you're saying.
Do you have any reason to believe the vents right to the side of the nose of the car would not be a high pressure area? I guess I am running on the assuming the Vararam works and that air would be "building up" on the front and nose especially of the car, with the effects only increasing as the speed goes up.
Do you have any reason to believe the vents right to the side of the nose of the car would not be a high pressure area? I guess I am running on the assuming the Vararam works and that air would be "building up" on the front and nose especially of the car, with the effects only increasing as the speed goes up.
Melting Slicks
Joined: Jul 2005
Posts: 2,990
Likes: 346
From: Mt. Pleasant S.C.
Apologies that it looks like a 5 year old did this. Art is not my strong suit. I was thinking that at the speeds your dealing with the airflow would begin to look like this, and the area of the vararam intake wouldn't actually be getting ram air.
But, with some googling I found this:
http://www.trackhq.com/forums/f303/c...corvette-6880/
It's a c6 pictured but it illustrates what I was trying to get with my question, and I think it answers it. In specific, the third one down. I guess it means that I was wrong.
But, with some googling I found this:
http://www.trackhq.com/forums/f303/c...corvette-6880/
It's a c6 pictured but it illustrates what I was trying to get with my question, and I think it answers it. In specific, the third one down. I guess it means that I was wrong.
Le Mans Master
Joined: Mar 2002
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From: PNW
If Vararam has done their homework, then I'm sure they have designed and placed their intake system inlet to where it's taking advantage of the ram-air pressure. I'm betting Vararam instrumented their intake and did some real world, on the road testing to verify the design.
OP, if you call Vararam, ask them if they can provide you with a ram-air pressure vs speed table like I provided in Post #7 above.
OP, if you call Vararam, ask them if they can provide you with a ram-air pressure vs speed table like I provided in Post #7 above.