10-17-2014, 06:10 PM #1
Maximum safe boost numbers for 91-93 oct pump fuel
I did a search on here and didn't really have any luck. I would like to know who is running higher boost engines on pump fuel and has it been safe and reliable. I am in the process of increasing boost to either an ET15.5 or ET18 and i was wondering who is running those wheels or similar boost numbers between 16-20#'s of boost safely on pump fuel. I have no problem upgrading internals like I did on my last engine but I guess what I am after is what are the maximum realistic numbers that are safe on pump fuel without too much fear of detonation. I am looking for a realiable rec boat setup and not a "well if you don't hold it for more than 8 seconds at wot, it should be ok" type setup. I ride in the northeast where the air temps range from 60-90* and water temps are usually between 60-75* when and where I ride. I realize air and water temps will affect that as well so it would be nice to know what everyone has been running for boost numbers safely on pump fuel along with their normal operating conditions. I would love to run the ET18 but don't want to get into the race fuel thing but I also hear alot of people run the ET18 on pump fuel with no issues so I am digging around trying to find out what the limitations on pump fuel with max boost vs operating conditions. Thanks for any input!!
10-17-2014, 06:56 PM #2
Also depends on amount of timing you will be running. So what amount of timing will you be running?
10-17-2014, 07:04 PM #3
10-17-2014, 07:08 PM #4
- Join Date
- Aug 2012
Too many variables to consider.plus i dont think many of us are actually logging knock but if we had to put a number id say over 17 and 8800rpm you start to roll the dice a bit.how long you hold it for and your tune up in the ski will all have an impact on what could be considered reliable for your kind of riding.
10-17-2014, 07:14 PM #5
10-17-2014, 07:21 PM #6
10-17-2014, 07:23 PM #7
10-17-2014, 07:59 PM #8
I really like the wheel a lot. Yes the 18 lb wheel pulls harder but considering all I have is retainers, my limit is 8700-8900 rpm with stock rods and pistons. I saw what 20-21 lbs. of boost can do to a stock motor and I do not want to risk it. A far as surge, it has a little flutter but it does not bother me at all. It does not shake or feel its not balanced. For a recreational ski its all I need.Going riding this Sunday and will enjoy it with a pitcher of beer and some chicken wings.
10-17-2014, 08:45 PM #9
I'm running the R3 with the 15.5 wheel. I run 91 in the summer and mix it with 94 in the spring and fall. Rpms around 8700 and afrs 11.9. Not sure if our gas up here is much different than yours.
10-17-2014, 09:38 PM #10
I have also thought about trying E85 either straight or as a mix to slow the burn down on the higher boost of 18+ pounds. I talked with Art earlier and he said the 15.5 will be fine on pump gas up in this region all season and the 18 would be iffy in the spring and fall but fine during the summer months of mid june to around mid september. He is located in Toronto which is only 2 hours north of me so he shed some light on the fuels needed to run these wheels safely and he highly recommended internal upgrades with the 18 but he also said he knows a bunch of guys who run the 18 with stock internals and pump gas all season with no issue but he didn't really mention where these guys run them like that so thats another reason why i am asking these questions. I want to know if it's a "cover my ass" type thing as most companies will do to either push product or be conservative or is it all legit and every one above the mason dixon line has to run race fuel or a mix of race/pump fuel with the ET18 lol. One thing Art did say with the Et15.5 was that all is needed is a RRFPR and stock injectors should be ok but I have heard repeatedly that the stock injectors are maxxed out around 14 pounds and around 8500 rpm. i tried that experiment with a C5/R3 with RC2 cam setup a couple years ago and it didn't seem to like the stock injectors so thats why I am going with the 725's and the R8 reflash which is tuned to those injectors and will work well with either wheel. I'm not doing the stock injector thing again with anything over a C3 wheel again.
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