Thread: Heat impact
07-16-2009, 08:00 AM #1
How much does the heat impact on the performance of our 4-tec?
Just 3 months ago in the cool season (air & sea temps in the lower 80s,
= under 25 celsius) I was getting everyday +76MPH @ 8.100 with a few runs at +77MH, with this setting:
07 RXP, green wheel in stock SC, XS IC, thru-hull, Riva thermostat, modded throtle body, Riva 3" front air, Riva grate, RE opas block-offs, 15/20R
We are now in the hot season (temps in the high 80s = above 30 celsius)
and I just finished installing a new X-charger, RRFPR, 4" front air.
The best I see now is 75MPH at 8.000
What kind of RPMs and MPHs you think I can expect with those new mods when the temps get back to lower 80s in October?
I am thinking basically 1 degree celsius = 100 RPM = 1 MPH ? correct?
07-16-2009, 08:37 AM #2
Hard to say
Humidity plays a factor too. How much has the humidity increased?
07-16-2009, 09:12 AM #3
we are now at the beginning of the monsoon, so it s still only 75%,
will probably go up to 80% next month
I think it was about 65% in the cool season, and usually 70% year average
07-16-2009, 10:00 AM #4
- Join Date
- May 2007
- Libertyville ILL
WOW that wether SUX up here on lake superior we get 55-70 degree water and 75degree air on the hot summer days some times I need an Ice breaker to Ride,,,, but then again my snomobile is wayyyyyyyyyy fast er than my ski
07-16-2009, 10:10 AM #5
I've seen rpms drop from 8550 to 8300 from April ( 70's temp ) to now ( 100-105* ). Water temp is now 95*. This is in South Texas. I got it all back & more went we had the boat out in Long Beach, Ca. Last week. That was until the tunnel de-laminated. POS hull.
07-16-2009, 11:21 AM #6
The heat and humidity will take from 200 - 300 RPM
07-16-2009, 04:54 PM #7
The temperatures play a big factor on you rpm's = speed.
Water heats up = less cooling
Outside temperatures higher = hotter intake air
All this together costs performance.
07-16-2009, 05:03 PM #8
yep, I have seen a drop in RPM's myself on my conversion. I was running 7900 RPM's when I first got it running from March 8th up until June during mudbug is when I seen a drop in RPMs from the humidity and heat.
In march temp was 81 degrees with 57 % humidity, much different now
07-16-2009, 11:02 PM #9
Guys, shouldnt my Riva thermostat protect me from the heat fade?
If I am still losing at least 200 RPM and 2 MPH in the hot season,
does this mean mine is not working properly, or it this mod generally inefficient? cost me 180$
Would I get any better results with a Rotax Racing 131 degree thermostat? costs 340$, really worth it?
07-17-2009, 04:48 AM #10
- Join Date
- Nov 2007
- Lincoln, NE
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