M90 in a 5.0 problems, blowing off the hoses !? Help

ghostdog5.0

Registered User
Hey guys, new to this forum and supercharging but not to mustangs or cars.

Anyways, I have installed an m90 in my 89' Mustang and its from a 93 tbird.

Everything seems to be hooked up right but I have a problem with the hose running before mass air flow blowing off ?

I have an aftermarket bypass valve but I am under the impression that it sucks, as it appears to not be functioning. When I am at idle , my vacuum gauge reads 0, so it is obviously getting boost.

I am running a 2 3/4" pulley with a 3 3/4" crank pulley so that should put the blower at approximately 12,000 rpm @ 6,000 engine rpm, well within the m90 limits.

Any ideas besides the bypass valve being crappy for the hose to blow off.

Also, when I didnt have the bypass hooked up, I had a breather in the valve cover fill spout and the fill spout was connected to the throttle body. I assume it was bleeding off there and thats why it didnt pop off. Whenever I would give it throttle you could see the rubber piece connected inbetween the MAF and throttlebody sort of balloon (about 1/4" more than usual).

Some pics are attached of my current setup. In the pics it doesnt show the bypass valve, but it is in place of the middle of the long pipe that runs by the radiator.

Any help would be greatly appreciated.

You can message me on AIM at screenname Beavis662
 

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that air filter sitting on the motor like that is gonna be sucking in so much hot air your whole car will probably melt :eek:
 
Spider said:
that air filter sitting on the motor like that is gonna be sucking in so much hot air your whole car will probably melt :eek:

I'm sure this is not the type of response he is looking for. If your not going to answer his questions, leave your comments elsewhere.
 
JimBowy said:
I'm sure this is not the type of response he is looking for. If your not going to answer his questions, leave your comments elsewhere.

no sense on being a dick i was just pointed out something i noticed. maybe someone can correct me on this. motor temps run so hot i would think that would me a big problem. I'm trying to learn as i go with these cars to, should i have started a new post with his pictures just to ask or make a comment about it ?

are you the forum police or something ?
 
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well the post asks for help regarding the bypass valve , not why is it running hot. I havent gotten to that point yet , so it doesnt pertain to my question.
 
Where exactly is it blowing apart? Is it where the hose attaches to the looooooong metal tube that runs from driver's side to passenger side? If that is the case, you may need a weld bead around the end of the metal tube to help hold the hose on. This will make sure the hose clamp cannot slide off the end of the pipe.

Also... what type of clamps are those that you are using?

As for the air filter sitting where it is.... well.... IF you care.... Spider was right. Even if you hadn't asked about that (yet). Along with the placement of the air filter, I would also be concerned about the lack of an intercooler. Eaton superchargers are notorious for being heat generators. The lack of an intercooler coupled with the placement of the air filter (sucking in already HOT air) is NOT likely to give you very good end results.

I would be willing to bet you will have some pretty big detonation/pinging issues that will require the timing to need serious retarding which will take away most of the benefit of the supercharger in the first place.

Whatever the case may be and whatever your end results are.... you DO have an (otherwise) pretty nice looking setup there that looks like it could prove to be quite fun when ya get it all worked out.

Have you had it set up long? If so, what are the results so far?
 
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ghostdog5.0 said:
Hey guys, new to this forum and supercharging but not to mustangs or cars.

Anyways, I have installed an m90 in my 89' Mustang and its from a 93 tbird.

Everything seems to be hooked up right but I have a problem with the hose running before mass air flow blowing off ?

I have an aftermarket bypass valve but I am under the impression that it sucks, as it appears to not be functioning. When I am at idle , my vacuum gauge reads 0, so it is obviously getting boost.

I am running a 2 3/4" pulley with a 3 3/4" crank pulley so that should put the blower at approximately 12,000 rpm @ 6,000 engine rpm, well within the m90 limits.

Any ideas besides the bypass valve being crappy for the hose to blow off.

Also, when I didnt have the bypass hooked up, I had a breather in the valve cover fill spout and the fill spout was connected to the throttle body. I assume it was bleeding off there and thats why it didnt pop off. Whenever I would give it throttle you could see the rubber piece connected inbetween the MAF and throttlebody sort of balloon (about 1/4" more than usual).

Some pics are attached of my current setup. In the pics it doesnt show the bypass valve, but it is in place of the middle of the long pipe that runs by the radiator.

Any help would be greatly appreciated.

You can message me on AIM at screenname Beavis662




On a SC T-bird, air is directed straight into the lower intake manifold during low engine load ,high vacuum conditions ( cruise and idle) and effectively bypassing the supercharger. Under high engine load conditions and low vacuum conditions the bypass closes and air is forced into the supercharger and then into the engine. Since the MAF meter is before the throttle body, all air entering the engine has been carefully measured and cannot be vented. The bypass allows us to run in 0 boost and even 20+ Hg vacuum conditions as if there was no supercharger attached to the engine.

The problem on your setup is that when you close the throttle excess pressure is building up while the engine rpms are coming down and blowing the hose off. If you are running a blow through MAF setup you could use a turbo style blow off valve to vent the excess air into the atmosphere before the MAF.

Jerry
 
The first thing I would do is go to a T-Bolt style clamp. Regular hose clamps are not meant for boost, and that right there could be a lot of the problem, esp. if you don't have a bead around the metal tube as mentioned earlier. As long as you have a bypass valve hooked up to manifold pressure, you should be okay on that.

I should of read your post first Jerry. Very good info there.

Thomas
 
Thanks for the replies Shockwave and Thomas.


Where exactly is it blowing apart? Is it where the hose attaches to the looooooong metal tube that runs from driver's side to passenger side? If that is the case, you may need a weld bead around the end of the metal tube to help hold the hose on. This will make sure the hose clamp cannot slide off the end of the pipe.

Also... what type of clamps are those that you are using?

Yes it blows off at the end there. For now I am just using regular hose clamps. I know..... I want to get it running first before I invest in constant torque stuff and change out to all aluminum everywhere stuff. But it is looking like I need to invest in stronger stuff.

The style bypass valve I am using now is the kind that vents to the atmosphere and stick into an intake tube. With that a vacuum line runs to the top of it.

I barely got the setup going this weekend.

Perhaps I should mention the mods.
89' GT , Ported Trickflow Trackheat Heads, Stage 1 cam, Streetheat lower / Sheet metal upper, Tweecer RT & PLX Wideband, 75mm TB, 1.6 Roller rockers, 3.73s, MSD 6a, Canton 7qt Pan+ Windage tray, 36LB Injectors, 200 amp Alternator, 75mm Pro-Mas MAF, 190lph fuel pump,Spec Stage 1 Clutch,SouthSide LCA's, Pro 5.0 Shifter, Steeda CC Plates / Springs, FMS Aluminum Driveshaft, New T5 w/ 2.95 first gear, Underdrive pullies, Zirgo 3300Cfm Elec. Fan, AFCO alum. radiator

I set everything up in tweecer and it fired right up.

Let me get this straight though. If I get a standard blowoff valve, doesn't that only function once the boost is at whatever psi it is rated at ? If that is so, wouldn't that not help me because my boost is at such a low level it wouldnt hit the blowoff valves release pressure?

Thanks
 
You can change the springs in a BOV to accomadate your boost levels. I think you can get them for as low as 8lbs.

Thomas
 
The Eaton is a positive displacement BLOWER. It just keeps pumping air even if you close the throttle and there is no where for it to go. There is no telling how much pressure the hose connections are seeing before they blow off. You need a blow off valve that is referenced to atmosphere I would think. For example, if you want 10 PSI to the motor, I would guess that you want the blow off valve to start venting at 12 psi, or something that would not hinder you to achieving your desired motor boost level.

I don't have any direct hands on with blow off valves. Some cars like the WRX STI have an internal blow off that recirculates back to inlet of the turbo compressor, as they have draw throught MAF.

Jerry
 
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I thought a wastegate limited max boost and a BOV released boost pressure when you quickly let off the throttle so nothing goes boom? A turbo guy would be best for that kind of talk me thinks..

But otherwise nice setup, I bet she will scream when everything is worked out!
 
First off....you need to SERIOUSLY consider a front mount intercooler on that thing. With the m90 being a heat pump like it is, i wouldnt doubt the supercharger has become a restriction in HP gains, and not a power adder. First step is to buy and install a FMIC. With your set up, it would be easy as pie. Something like this would do fine.
txs_evo_fmic.jpg
 
Yeah, I was kind of thinking the same thing. I would guess you will be using 50-70 hp on average to turn the blower, depending on rpm. With the heat a stock eaton creates, and the length of tubing you have before the TB, you may not see much of a HP gain. I think a the majority of your power will be lost in heat and drive restriction. A Front Mount would be very easy to fab up considering the location of your blower, and would make a huge difference.

Thomas
 
I didnt read all of the answers to that post but I think someone touched on it. The problem is that the blower is still pumping when the throttle closes. This causes a LOT of pressure in the piping with the throttle closed. I would be willing to bet money if you do a moderate (even 1500) rev and then let off that it will pop off of the pipe. Our blow off/bypass valves are only like 1.25 to 1.5 inches (I can get an exact diameter if you need) and keep our cars from having the same problems. If you stand on the engine, you can watch it activate. It is operated by vacuum and a pushrod. I will post pics if you need. But for me to do that...we need to see a video:) ....

Chris
 
I have the parts from the thunderbird but I dont see how I could package that blowoff design into my setup. I am simply out of room.

Im still confused about what is going on at idle. Should I have no boost at all at idle and my normal vacuum ?
 
These guys are hinting at the solution to your problem. If you wish to run the M90 in that configuration you will have to run a very large bypass valve (not a blow-off valve) and vent it to atmosphere before the MAF. However, this will create some tuning problems that may not be able to be so easily solved. If you push compressed air past the MAF you will run lean under boost. The MAF adds fuel in reference to airflow vs. pressure in the tube, not atmospheric pressure. It can't compensate for boost. If you ran something like a Pro M optimizer and a wide band 02 meter you could probably get it to work. But, by the time you get the optimizer and the huge bypass that you'll need you'll have spent a few bucks just to get you to square one.

Simpler solution is to put the TB and MAF both in front of the blower. That will solve all of your problems at once. The addition of a bypass valve will then become a secondary issue. You can run either with or without the bypass but it will run much cooler with one. Without a pypass valve or intercooler you could see 300+ deg intake charge temps which will cause detonation and engine damage.

You also need to think about ignition timing. If you run boost into the motor without a timing retard you will have problems from that as well...

Getting stronger pipes and clamps is not the solution. At the 4-5psi that the blower will make on your motor you won't need stronger stuff. Instead you need to eliminate the pressure in the system. Effective boost and excessive pressure are two different things entirely.

You might also want to see about creating a little more belt wrap on the blower pulley but that is getting ahead of yourself.

:)
 
ghostdog5.0 said:
I have the parts from the thunderbird but I dont see how I could package that blowoff design into my setup. I am simply out of room.

Im still confused about what is going on at idle. Should I have no boost at all at idle and my normal vacuum ?

Yes, you should have full vacuum at idle. You can run an aftermarket bypass valve easily enough. www.superchargersonline.com has some.
 
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