Thread: Low RPMS....Now what?
05-08-2008, 08:19 PM #1
Low RPMS....Now what?
Ok.... Here's the deal.
At the end of last summer I was running a S1 at 73.6MPH/8100RPM. At that time I had the following mods: 14/19R, Filled holes, rev. bucket mod, intake grate, sponsons, catch can, wedge, OPAS block offs, Flowrites, and riva front intake.
Over the winter I added the following: XS IC, boost gauge, Riva Stage 2 wheel, metal washers, new needle bearings, front motor mount, 15/20R, X-BO block offs, R&D Steering nozzle, Adjustable venturi nozzle, iridium plugs, IC filter, Thru-hull exhaust, Flared J-Pipe, and gutted waterbox.
Here's what's going on.
On the first couple of rides this year I had a few problems.
-I didn't seat my J-pipe right on re-installation. There was exhaust smoke coming from the V-band clamp. I fixed that easily.
-The next problem was with the XS IC. The one that I installed had a leaking core. It was causing the engine compartment to fill with steam. I bought a new XS and now that problem is no longer.
Now to the RPM issue.
A week and a half ago I went out riding to test the new XS and everything seemed to be running better. However I was only turning 7650-7750 RPM and I was about 7.8# of boost. I didn't have the GPS with me that day. I had the 81mm ring in the nozzle.
Today I ran on about 2/3 tank of gas. I put the 83mm ring on. I was only turning 7400-7500 RPM & about 6.5# of boost. The top speed on the GPS today was only 70.5MPH. With the larger ring the RPMs when down!!!
Please someone help.
05-08-2008, 08:23 PM #2
05-08-2008, 08:32 PM #3
..... also, was your impeller new out the box? If it was used chances are someone could have added some pitch to it and it's just too much pitch for your setup.
05-08-2008, 08:32 PM #4
05-08-2008, 08:34 PM #5
05-08-2008, 08:40 PM #6
05-08-2008, 08:44 PM #7
05-08-2008, 08:44 PM #8
Ok... Time to re-seal everything.
05-08-2008, 09:34 PM #9
Is there anyway to pressure test the the system on the 4-tec to look for leaks?
I remember with the old Saab's that we used to be able to do some blocking off and pressurize the system to look for leaks, but that was obviously different. Just curious.
05-14-2008, 06:20 PM #10
Just got done re-sealing everything.
I found the leak..... I guess it is pretty obvious that a misplaced, half falling off kids room would cause a pretty major boost leak.
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