TheMustangLoveR

I typed more than I thought, so if you have patience to understand my problem read on

Okay so I have been having issues with my supercharger that I posted abouta while back. The setup is an intercooled Vortech V2. My problem is that when I let off the throttle and let the engine down-rev (while in gear), the engine downrevs roughly and the car slightly bucks. Also, in some situations, upon letting of the throttle and pushing in the clutch, the engine stalls. My tuner and I discussed it today and he checked the fuel tables, etc. to determine what the cause was. He concluded that it comes down to the path that the compressed air is taking upon letting off the throttle. Instead of backing up and leaving via the bypass valve and going into the supercharger inlet, it is backing out of the intercooler and marching back through the discharge of the blower, causing the loud flutter that I always hear upon letting off the throttle. We thought the loud flutter was the bypass valve, but he said that he's never seen one this loud (sounds like a blow off valve on a turbo'd car) and so it seemed suspicious. So we pulled the vac line off the bypass to force it to stay closed (to see if the car acted differently), and throttled the engine, and sure enough the flutter was still there WITH the valve closed. So it's not the bypass valve dancing up and down causing the flutter, but actually air moving back over the impeller causing the fluttering sound. He said, and, mind you, no one on any message board has suggested this, that I should move the bypass valve to be before the intercooler (meaning near the blower on the discharge side), and this may solve the problem.

So we decided to try this some time next week whensuddenly Ihad my stroke of...well...something. Tomorrow I'm re-mounting my intercooler to be inside the bumper (was below the bumper before...because of the previous owner's ridiculous doing). So tomorrow I'll march over to a muffler shop and have them weld in a bung for a bypass on my new piping for the intercooler. That means I have to cap off the existing bung for where the original bypass is. And it clicked! Why don't I run two of these little bastards? Can't I leave the existingbypass where it is, and go ahead and add in another one where my tuner told me to place it? I'll simply tee them together and have them feed into the supercharger inlet like they're supposed to.

That way, wherever the hell the excess boost wants to leave, it can. What do y'all think? Is this common? Stupid? Plausible?

P.S. a ton of people have suggested getting something like a Vortech mini-race bypass valve. Yea...I'm not spending $300 on that crap. And besides, the symptoms only occur in low boost situations.

Puerto Rico 4.6

I got the mini race(180 on ebay)and never had that problem. But yes you can use two of the stock bypass valves ...i have seen plenty ofset ups like that. Good Luck

FDNYBullitt

I had a very similar problem with mine, the stalling part and after going over EVERYTHING we figured it might be the stock by-pass. I called Vortec, they sent a new one and it cleared it up. While talking to them about this and raising the boost in the future we got on the subject of running 2 stockby-pass valves instead of spending for a miniand to my surprise the guy didn't try to sell me a mini-race, which I thought he would. He explained it very simply to me ( although he wasn't supposed to )that all thats needed is to drill out the existing bung on the mid pipe a little and then just use some heater hose and fittings, tee in 2 of the stock ones and its good for 16-18 lbs of boost, we'll find out soon.

2000GT4.6

Your problem is called "compressor surge" and it can be deadly to the blower compressor (real deadly).

The solution is either what you said, or get a mini race. You can get em brand new for 220-230 bucks, and its a pretty simple install. Arn't the stock bypasses fairly expesive anyway? The mini race seems like a better soluiton.


ALSO, make sure no matter what setup you use, make sure your pointing the side of the bypass thats in the intlet TOWARD the blower. If its pointing straight in, or towards the MAF sensor, you can get maf backwash and end up with a real big problem.

BTW, the reason its doing so in low boost situations is because you don't have a blowoff valve, you have the bypass. The bypass opens on suction, aka when your not building boost but have the throttle out. Since you don't have a blowoff, and the boost is regulated by the pulley and not air being let out of the system, you don't have the problem at WOT when the blower is making actual boost.

TheMustangLoveR

My entire problem right now is I AM getting MAF backwash. That's why my fuel is getting messed up after maintaining a certain rpm for a while. The air is backing up through the blower and going back out the MAF, and the computer starts cutting fuel when it shouldn't. The mini-race also requires a flange and etc...probably near $300 all said and done right? Eeesh. I happen to have two bypasses right now...the stock one and a slight upgrade (still Bosch though). We'll see what happens!

slow99GT

I have a lot of friends with turbos. This has happend to some of them when the spring on the BOV is to stiff or it is improperly working. Try getting a new or if you can take it apart try to make the spring not still LOL... thats sound pretty funny but it might work. I know on most bovs you can adjust the tension on the spring.

2000GT4.6

If your getting maf backwash, and no compressor surge, what you need to do is point the air towards the blower instead of the maf. Are you using an aftermarket intake pipe, or the stock vortech unit (aka powerpipe or stocker)? The stock one should not have this issue.

It sounds more like compressor surge than backwash, the way you describe it. On a I/C vortech alot of people have issues with the stocker bypass not being big enough.