Thread: Low boost and low rpms
08-18-2010, 10:05 PM #1
Low boost and low rpms
Well I still have something wrong, here is the story:
Was running a Gen2 wheel at 7950rpm and 72.5mph all day w/8.5psi boost, 82mm ring
Got an x-charger and ran 8100rpm and 74.0mph all day, no rrfpr
Installed rrfpr same thing, 8100rpm ran great
Parked for 2 hours hit the lake and saw only 7700rpm
Rpm dropped to 7600, Found oil in my IC, cleaned it out
Put Gen2 back in, 83mm ring, added 2mm to the prop, hit only 7500rpm w/8psi boost
Confused so installed x-charger and new 4" got 7600 rpm-8psi boost, had low slip
Installed Viton seal, set slip to 13psi, new wear ring, took .5mm out of the prop-7700rpm and 9.5psi boost.
That is where I am sitting right now, I have all the simple things done except for checking for a boost leak, I have had the IC out so many times I am certain there is no leak there, would have seen oil leaking out too from my leaking chargers. The only place that it could be leaking is the nipples for my Boost guage an rrfpr or intake manifold. What do you guys think of all this? I dont think I could even lose enough air out of one of those spots to lose that many rpm's...
08-19-2010, 05:30 AM #2
You should took prop back to 15/20R with nozzle 83 mm and see what happen?? if better you changed nozzle to 82 mm and test it again,if the rpm over 8160 rpm, added +1 mm step by step.
08-19-2010, 08:57 AM #3
The thing thats holding me back from doing that is when I first had these problems the prop was untouched, with both superchargers. Also, I have low boost as well which is likely where the missing rpms are i think. Or if the prop is too steep will it not get full boost. 1.5mm isnt much.
08-19-2010, 11:04 AM #4
08-19-2010, 01:45 PM #5
Worked on it this morning. Found a decent size boost leak at 1 IC pipe and smaller one at another 2 joints. Got them sealed up and it holds over 10lbs for more then a minute. I have a very slight hiss at the blockoff but not worried about that right now, getting a metal blockoff this winter. On my way to water now to see how it runs, will bend my prop from there. Wish me luck!!!
08-20-2010, 05:55 AM #6
This is what you need to do a boost leak check on your system. http://www.siliconeintakes.com/produ...ae64e1a3b36789. I use it all the time and you'll be surprised as to were you will find some leaks. Only thing you have to do is hook up a air source to it and only add air pressure to it that is the equivalent to what the output of your S/C should be. I'm told the Manifold will hold 35 psi but the max I've pumped thru my system is 16 psi just to be safe.
Godd luck. This adapter bolts to the intake of the S/C
08-20-2010, 11:28 AM #7
That thing looks pretty sweet. I ended up using the rubber adapter from a Riva 3", cut a hockey puck in half and drilled a hole in the middle to install a valve stem with a nut. Held perfect and worked great.
08-20-2010, 03:23 PM #8
Im in need of some real help, With the above posts my problem is still the same. My prop is back to stock now though. I am only getting 7600rpm, 7700 with the seat off. There are no boost leaks, new wear ring, 15/20r prop, 13lbs slip. Im lost dont know where to go from here! Im thinking compression test, installing stock fuel pressure regulator(problem started shortly after install). Is there any possibility that the knock sensor biggyback harness could be screwed up? I am getting really tired of guessing... Dealer told me that there is nothing his scanner could do for me without a code. One other thing, the "maint" light has been on for prolly 25 hours now and I just past 80 hours, could it possible need to be reset?
08-20-2010, 06:04 PM #9
Any suggestions guys? I know there are many people on here that are alot smarter then I am...
08-20-2010, 06:20 PM #10
check your fuel pump, clean green air sensor from oil, clean cam sensor
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