Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 28
  1. #1

    Join Date
    Aug 2006
    Location
    Gonzales, La
    Posts
    2,145
    +1
    9

    Screwy Riva dyno numbers. . .

    Okay, so I been trying to figure out how fast I could go with an XS intercooler and S3 supercharger with the stock ECU and 42 lb injectors. This would be basically a S3 but limited to 8100 rpm. Looked up the dyno numbers and found this (All numbers at 8100 rpm):

    Stock: 209 hp @ 7.3 psi
    Add 3" intake: 211 @ 7.7 psi
    Add Vortec S2 impeller: 215 hp @ 8.4 psi
    Add Intercooler: 229 hp @ 8.7 psi
    Add S3 impeller/cover: 274 @ 9.9 psi

    The S3 improvement over S2 just doesn't make sense to me. With only 1.2 psi additional boost, it's making an extra 45 hp? My turbocharged 388 Z28 doesn't even gain 45 hp for every 1 psi boost! Either they are understating the S2 numbers, or overstating the S3 numbers.

    For kicks and giggles, I did a little math. The baseline premise here is that speed is proportional to the square root of power. This holds fairly true for anything drag-limited (car top speed, boat top speed, even gas and liquid flow in pipes).

    Stock is 68 mph. Lets say we install a Riva Grate and Wedge, so now it goes 70 even.

    Add the air intake, and you only get to 70.3.

    Add the S2 impeller, and you only get to 71.

    Add the intercooler, and you only get to 73.5 mph.

    Add the S3 blower, and you get all the way to 80.3 mph.

    All the numbers seem about right except the full Stage 2 package, which runs 2-3 mph faster than the calculated 73.5.

    If I reverse the calculations going by what people run and calculate hp, the fastest S2's run around 76.5 mph (RXP'in in MI), while the S3 minus ECU runs about 80 (rxp244). To run these numbers, the power would need to be 250 hp and 273 hp respectively.

    By this math, the S3 minus ECU matches up about perfect, while the Stage 2 power would need to be quite a bit higher than Riva's advertised 229 hp. Is it also coincidence that the 2008 RXP will have an upgraded impeller and external intercooler (sounds an awful lot like a Stage 2) and advertises 250 hp, not 230?

    The bottom line is that I believe the Riva Stage 2 is underrated in hp, but I'm not sure why.

    Thoughts?

    Mike
    Last edited by engineermike; 08-18-2007 at 08:53 PM.


  2. #2
    Site Admin Green Hulk's Avatar
    Join Date
    Apr 2005
    Location
    Morgan City, LA
    Posts
    36,398
    +1
    2,524
    Quote Originally Posted by engineermike View Post
    The S3 improvement over S2 just doesn't make sense to me. With only 1.2 psi additional boost, it's making an extra 45 hp?

    You're leaving a very important factor out of the equation. The ECU! The RIVA ECU has a bunch more timing than the stock ECU and operates at 400 more RPM's than the stock ECU. More RPM's = more HP so boost is not the single determining factor.

  3. #3
    Site Admin Green Hulk's Avatar
    Join Date
    Apr 2005
    Location
    Morgan City, LA
    Posts
    36,398
    +1
    2,524
    Quote Originally Posted by engineermike View Post
    Is it also coincidence that the 2008 RXP will have an upgraded impeller and external intercooler (sounds an awful lot like a Stage 2) and advertises 250 hp, not 230?
    The supercharger in the 08 is not even comparable to the supercharger impeller that comes with the stage 2 package.

  4. #4
    Closed mouth no get fed,...... travelboysteve's Avatar
    Join Date
    Jun 2007
    Location
    Orange County
    Posts
    199
    Quote Originally Posted by Green Hulk View Post
    The supercharger in the 08 is not even comparable to the supercharger impeller that comes with the stage 2 package.

    OK, Mr. 91.8,......I have a theory,......you went and rode the 08. This we know,.....you completely built a bada** 07 and are now selling it for cheap,......
    I have several theories here,......
    You became a crackhead and are selling everything you own,......
    Nope,..that doesn't sound right,.......
    You forgot to pay your vendor bills and have hocked your stuff,.....
    Nope,....that doesn't sound right either,.......
    You think it will be comparable in price to mod the new 08's as compared to 04-07, maybe the 08's have a new hull design and it will do WELL over 90 mph because you're in the know, and knowing what you do for a "hobby" I bet you'll get to 100 mph easy,....... Just a thought,......

  5. #5
    I don't think the S2 is underated at all. Like Jerry said, you have to take into acount that Riva is doing the dyno test with their ECU on. It's timing is allowing it to produce more HP than the stock ECU. That's why you notice the 45HP difference between the S3 and S2 dyno at 8100 RPM. Yes the RS3 SC is worth a portion of it, but like you said no way it's 45 HP. Mike also remember that boost isn't everything. The RS3 SC is moving a larger volume of air too. You have to consider all the other parts in the full RS3 that are helping too. That 45 HP difference at 8100 RPM is divided up a few ways.

  6. #6
    Quote Originally Posted by travelboysteve View Post
    OK, Mr. 91.8
    If I'm correct that was by Stan, not Jerry at MB3 on the GPRXP. Jerry forgot to wear the aerodynamic helmet that Lance Armstrong wears so he only say 91.5mph or something around there.

  7. #7
    AKA: Larry lafjax's Avatar
    Join Date
    Jul 2006
    Location
    Jacksonville, Fl
    Posts
    3,032
    Quote Originally Posted by engineermike View Post
    Stock is 68 mph. Lets say we install a Riva Grate and Wedge, so now it goes 70 even.
    Add the air intake, and you only get to 70.3.
    Add the S2 impeller, and you only get to 71.
    Add the intercooler, and you only get to 73.5 mph.
    Add the S3 blower, and you get all the way to 80.3 mph.
    Mike
    I know you are talking about an RXP, but I have all this stuff on my [email protected] with 4" intake & S3 and cannot break into 69.

  8. #8
    Closed mouth no get fed,...... travelboysteve's Avatar
    Join Date
    Jun 2007
    Location
    Orange County
    Posts
    199
    Quote Originally Posted by RXPkid View Post
    If I'm correct that was by Stan, not Jerry at MB3 on the GPRXP. Jerry forgot to wear the aerodynamic helmet that Lance Armstrong wears so he only say 91.5mph or something around there.

    hahahaha, I stand corrected,....

  9. #9
    Closed mouth no get fed,...... travelboysteve's Avatar
    Join Date
    Jun 2007
    Location
    Orange County
    Posts
    199
    Quote Originally Posted by lafjax View Post
    I know you are talking about an RXP, but I have all this stuff on my [email protected] with 4" intake & S3 and cannot break into 69.

    But your sig says 70.2
    R U fibbin?

  10. #10
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Location
    Mesa, AZ
    Posts
    16,712
    +1
    85
    Gentlemen.
    HP is not linear. It is an equation. It's a number calculated.

    Now the one thing you are leaving out is the rpms, which effect both calculated hp and of course the real life application.

    One HP number is taken at 8100. Another HP at 8500. They will be a tad different, and calculate differently.

    You MUST take into effect the torque and rpms of the calculation...and the torque isn't flat or linear either. So questioning it, without having all the details AND doing the equation will leave you scratching your head.

Page 1 of 3 1 2 3 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. How about these Dyno Numbers?
    By Hecyan in forum 4-Tec Performance
    Replies: 12
    Last Post: 03-09-2007, 08:45 AM
  2. Post your RIVA RXP Stage 1 numbers
    By RXP-REX in forum 4-Tec Performance
    Replies: 8
    Last Post: 06-27-2006, 10:54 AM
  3. Riva Stage II+ Numbers For anyone Interested:
    By Sirhc7897 in forum 4-Tec Performance
    Replies: 17
    Last Post: 05-30-2006, 04:17 AM
  4. Riva Dyno Testing
    By Kinchyle in forum 4-Tec Performance
    Replies: 4
    Last Post: 10-06-2005, 08:19 PM
  5. Where are the Riva numbers coming from?
    By Burnwater in forum 4-Tec Performance
    Replies: 4
    Last Post: 08-05-2005, 02:46 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •