Quote:
Originally Posted by csx4910
9.5:1. I believe others have always run 91 octane in these motors without problems. I just know hte hesitation goes away and it feels like I picked up quite a few deat of the pants horsepower with 100 octane in the tank
|
Ron,
I believe the CR is 10:1, but I could be wrong.
http://dealer.webmakerx.net/Images/S...te_engines.pdf
go to page 2 of the PDF brochure.
The 511 owner's manual says:
"The Roush EFI engine was designed to perform with 91 or higher octane unleaded fuel. Please use the highest grade of fuel available at the time of fill up to ensure the best performance out of your Roush Performance engine."
BTW, there's a new version of the owner's manual and installation manual for the 511iR with the Accel/DFI system. I think I have your email address and will send you an email to give you further info. Big emphasis now on making sure your engine is not overheated:
"Your engine is equipped with a 180° Thermostat. You are required to provide an engine cooling system that will maintain a maximum coolant out temperature below 220°F under all operating conditions."
(red type above on the emphasis is there in the manual too)
The 180 degree thermostat is a change, it used to be a higher set-point thermostat, 200 degrees I think. Mine was changed out to the new lower setting thermostat. So far the maximum temps I've seen driving in 100 degree F OAT was 85 deg. centigrade (185 deg. F), I always use the auxilliary fan when temp is 80C or higher and it seems to hold it there ok. I asked Charlie to really go over the cooling system with a fine tooth comb. He sealed off some areas where he found air could sneak around the radiator.
My engine idles at 1000 rpm which is right on with the owner's manual. At very high OAT's when getting off the throttle the engine will immediately drop down to about 1300 rpm then slooooowwwly drop down into a 1000 rpm idle. If this happens a quick blip of the throttle drops it immediately down to a nice 1000 rpm idle. An occassional liveable quirk in my opinion. I don't want to take the chance and mess with fuel/temp curves to try to deal with what I consider to be a minor thing. So far no hesitation issues.
In my experience the only way to tweak the EFI is to get Roush to do it by having the local shop download data from the ECU and upload it to Roush along with a detailed description of symptoms for analysis by their experts, and then have Roush send new data to the local shop for loading into the ECU. Sounds easy but remember, this is Roush customer service we're dealing with so good luck. I had the local EFI guru try to tweak mine once, with Roush's approval since it was under warranty, and he only made things worse. Roush ended up having to analyze the problem and fix it.
That was when both our engines were new and we were having EFI problems Roush put their EFI expert on a plane and sent him out here to troubleshoot. He rode along in the passenger seat with a laptop on his lap that was wired up to the ECU. Tweaks were made to the curves under real-time, real-world driving conditions in the actual car. Now that's the dream way to fine tune an EFI system.
My car has a Fuel Safe racing cell (as does yours?) that uses an electronic quantity sensor that is almost completely unreliable. To make it work it seems to need recalibrating after about every second fill up, which is not practical.
Pegasus - Fuel Safe Fuel Level Sending Unit Set-Up
So I always use the trip meter. Let me know if you come up with a fix.