Tuning question, I think? PART II

[Tommy Gun]

LOL

I have a problem similar to Harley Dealers, but different. :grin:


On my 2002 GT, 4.6L w/ a procharger and a blow off valve set around 8 PSI.

At the track I was noticing that around 5500-6000 rpm at times it would just fall on it's face.

I think it's the blow off valve blowing off, but should it be feeling like that?

I would think it would just blow off a pound or two to level out at 8 psi right?

It a distinct loss of power although very manageable.

Has anyone had this type issue w/ a centrifugal blower and a blow off valve before?

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[blackshelby]

Those valves(almost look like a TB blade) if they are opening usually will go wide open if overcome by boost.
try blocking it off for one run if possible
How about spark plugs/ spark gap sure you not blowing out the spark

[Tommy Gun]

Those valves(almost look like a TB blade) if they are opening usually will go wide open if overcome by boost.
try blocking it off for one run if possible
How about spark plugs/ spark gap sure you not blowing out the spark


What do you mean block it off? Not sure I know how to do that.

I haven't checked plugs since the track. Again not sure what you mean by blowing them out?

[Birdman]

What do you mean block it off? Not sure I know how to do that.

I haven't checked plugs since the track. Again not sure what you mean by blowing them out?

If the gap is too much , when the boost is increased to the max it may be too difficult for the spark to jump the gap if the gap is too wide. This is what is refered to as blowing out the plugs...

As far as the bypass valve is concerned plug off the vac line going to it so it doesn't open at all.I think that may be all you need to do to test it.

[Carnut]

How about your rpm limiter. If memory serves me right, it kicks in at a little over 5700 rpm.

Just a thought.

[Tommy Gun]

How about your rpm limiter. If memory serves me right, it kicks in at a little over 5700 rpm.

Just a thought.


Hmm.. I'll have to check on this car what it's set at, but at the track I have been shifting at 6000 rpm in the straights.

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[Tommy Gun]

If the gap is too much , when the boost is increased to the max it may be too difficult for the spark to jump the gap if the gap is too wide. This is what is refered to as blowing out the plugs...

As far as the bypass valve is concerned plug off the vac line going to it so it doesn't open at all.I think that may be all you need to do to test it.


Okay, I just looked through hundreds of pictures of blow off valve and can't find mine. Mine has no vacuum line? It is a mechanically set valve. It has a nut at the top that you screw in or out to set?

I'll get a pic tomorrow if I think about it.

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[Tommy Gun]

Also, my mechanic set up the S/C and plugs. How would I know what setting to put the plugs? Is there a rule of thumb or do I need to see what others have used?

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[blackshelby]

Also, my mechanic set up the S/C and plugs. How would I know what setting to put the plugs? Is there a rule of thumb or do I need to see what others have used?

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Bill
All blower valves should have a vac line to it. If its just a spring setup then adjust it so the spring is real tight but again you should have a vac line on it. A vac line under boost help keep the the pressure equal on each side of the valve under boost and when off the pedal the vacuum will help open the valve quicker.
You have to pull the plugs to check.
Gap .025-.03 max on that setup

[Tommy Gun]

Bill
All blower valves should have a vac line to it. If its just a spring setup then adjust it so the spring is real tight but again you should have a vac line on it. A vac line under boost help keep the the pressure equal on each side of the valve under boost and when off the pedal the vacuum will help open the valve quicker.
You have to pull the plugs to check.
Gap .025-.03 max on that setup


I'll have to check, but I don't remember any sort of vacuum line going to it?

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[Tommy Gun]

I think this is what my set up looks like. I'll check tomorrow.

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[Birdman]

I think this is what my set up looks like. I'll check tomorrow.

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That looks like a relief valve not a boost by-pass valve. A bypass valve is designed to open and allow compressed (boost) air back to the inlet side of the blower when the throttle closes in order to prevent pressure build up against the throttle plate.

[Tommy Gun]

That looks like a relief valve not a boost by-pass valve. A bypass valve is designed to open and allow compressed (boost) air back to the inlet side of the blower when the throttle closes in order to prevent pressure build up against the throttle plate.


I don't know. I just know it prevents too much boost in the tube leading to the throttle?

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[blackshelby]

I don't know. I just know it prevents too much boost in the tube leading to the throttle?

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That's a pop off valve usually used with turbo's. Prevents an over boost condition. Really not the correct valve that should be used with your setup unless you ran that along with a surge valve.
That valve can also cause a rich condition if it opens and releases boost if not using a blow through meter. The valve would need to be before the MAF meter to prevent a rich condition.
If not the MAF meter measured the air already and thinks the air is going in the motor, so it will deliver fuel for that amount of air even though its not being used.

[Tommy Gun]

That's a pop off valve usually used with turbo's. Prevents an over boost condition. Really not the correct valve that should be used with your setup unless you ran that along with a surge valve.
That valve can also cause a rich condition if it opens and releases boost if not using a blow through meter. The valve would need to be before the MAF meter to prevent a rich condition.
If not the MAF meter measured the air already and thinks the air is going in the motor, so it will deliver fuel for that amount of air even though its not being used.


It is way before the meter.


I have the S/C, then the tube w/ the valve, then through the air to air cooler, then the tube w/ the MAF, then to the TB.


Is there something better I should be using?

Does this set up hurt something?

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[blackshelby]

It is way before the meter.


I have the S/C, then the tube w/ the valve, then through the air to air cooler, then the tube w/ the MAF, then to the TB.


Is there something better I should be using?

Does this set up hurt something?

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Thats OK to limit boost but you should have a surge/bypass valve in the system too.
What happens if you don't have one when you take your foot off the gas pedal and the TB closes you have a ton of air in the blower tubes with no where to go, that will actually try and turn the blower impeller backwards.(it will also makes the car surge or buck if cruising with no surge vavle) Its hard on the blower and hard on the blower belts. (it can also cause belt slippage without the surge valve)
If fact thats another thing to look at make sure your belt is not slipping at the higher RPM's ,look for black dust around the blower pulley.(make sure the blower belt is tight and I mean tight)

[Tommy Gun]

Thats OK to limit boost but you should have a surge/bypass valve in the system too.
What happens if you don't have one when you take your foot off the gas pedal and the TB closes you have a ton of air in the blower tubes with no where to go, that will actually try and turn the blower impeller backwards.(it will also makes the car surge or buck if cruising with no surge vavle) Its hard on the blower and hard on the blower belts. (it can also cause belt slippage without the surge valve)
If fact thats another thing to look at make sure your belt is not slipping at the higher RPM's ,look for black dust around the blower pulley.(make sure the blower belt is tight and I mean tight)


So you're saying this won't act also as the surge valve? When the TB closes and boost is in the pipe won't this limit teh pressure still below 8 lbs? Maybe you are speaking of a different placement for a surge valve?

I need a schematic. LOL

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[Birdman]

So you're saying this won't act also as the surge valve? When the TB closes and boost is in the pipe won't this limit teh pressure still below 8 lbs? Maybe you are speaking of a different placement for a surge valve?

I need a schematic. LOL

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How about some pics of what you have first and we go from there......

[blackshelby]

So you're saying this won't act also as the surge valve? When the TB closes and boost is in the pipe won't this limit the pressure still below 8 lbs? Maybe you are speaking of a different placement for a surge valve?

I need a schematic. LOL

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Correct it will not act like a surge valve. Thats a pop off valve it will only open if exceeds are certain boost level.(or thats at least the way you are using it if you do not have it hooked up to a vacuum port) Is there a vacuum port on that valve you have?
You can have a surge valve exactly where you have that one. A surge/bypass valve would be open under a vacuum conditions and closes under a load.

[Birdman]

Correct it will not act like a surge valve. Thats a pop off valve it will only open if exceeds are certain boost level.(or thats at least the way you are using it if you do not have it hooked up to a vacuum port) Is there a vacuum port on that valve you have?
You can have a surge valve exactly where you have that one. A surge/bypass valve would be open under a vacuum conditions and closes under a load.

I would like to see where his MAF is located in the system too.

[Tommy Gun]

I'll get some pics and confirm where everything is later.

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[Tommy Gun]

I'll get some pics and confirm where everything is later.

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Okay, ready? :waiting:


LOL


I did find a bypass valve as well. :ohsnap:


This is what I call the blow off valve...

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08460.jpg


http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08465.jpg



Here is the vac. operated valve...

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08462.jpg


Black tube is from the air filter to S/C, silver tube is from the MAF to the TB

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08463.jpg

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08461.jpg


Belt is pretty tight. I do see some black dust near the Alt because the alignment at this point is not 'exactly' perfect. It is the only way this huge S/C fits. LOL

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08464.jpg


At TB...


http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08466.jpg



Basic set up...


http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/valve20001.jpg


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[blackshelby]

Okay, ready? :waiting:


LOL


I did find a bypass valve as well. :ohsnap:


This is what I call the blow off valve...

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08460.jpg


http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08465.jpg



Here is the vac. operated valve...

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08462.jpg


Black tube is from the air filter to S/C, silver tube is from the MAF to the TB

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08463.jpg

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08461.jpg


Belt is pretty tight. I do see some black dust near the Alt because the alignment at this point is not 'exactly' perfect. It is the only way this huge S/C fits. LOL

http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08464.jpg


At TB...


http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/DSC08466.jpg



Basic set up...


http://i670.photobucket.com/albums/vv61/fastestshelby2/2002%20INTAKE/valve20001.jpg


.

LOL
setup is correct

[Tommy Gun]

So what might my original problem be?

Spark plug gap?

Need a better Vac operated valve?

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[Birdman]

First you have to check the plug gap and condition of the plugs...should be about .25 to .30 gap.

Next you have to be sure the "bypass valve" is not opening at 5500 - 6000 rpm dumping your boost. You can do this by plugging off the vac line to the bypass valve and running the car.

Are you loosing "boost pressure" @ the 5500 - 6000 rpm level if so it could be either the bypass valve bypassing prematurely or the "8#blow-off valve opening prematurely.

Question....what boost are you making @ 5500 to 6000 rpms?

What boost would you make if you plugged off the blow off valve and ran the engine to 6000rpm???

[Tommy Gun]

Okay, not sure if I know how to check such things w/o it being on a dyno and someone checking it for me.

Which would be the guy who tuned the car, which is the guy who's tune I dumped for the Sniper tune, which will ask me why I haven't been back to correct the GT500 tune. :banghead:

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[Birdman]

You don't need a dyno to check these things out dufus.....:no: After you pull the plugs , check them and regap them, plug off the vac line and take the car for a spin.....watch the boost guage and rpm's.

[Tommy Gun]

You don't need a dyno to check these things out dufus.....:no: After you pull the plugs , check them and regap them, plug off the vac line and take the car for a spin.....watch the boost guage and rpm's.


It's a Mustang GT.

I don't have a boost gauge. :ohsnap:

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[Tommy Gun]

What do I hook a boost gauge to if I get one? :hiding:

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[Birdman]

It's a Mustang GT.

I don't have a boost gauge. :ohsnap:

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What do I hook a boost gauge to if I get one? :hiding:

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You should have a boost guage if you have a SC......:trouble: Any vac port in the intake manifold will do....

[Tommy Gun]

Joe, I need a boost gauge. LOL

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[badboy500]

Get a boost gage first and check the plugs. Gap them at 28 if there good. Test drive the car. Report back. Easy.:tease2:

[Gr8snkbite]

It's a Mustang GT.

I don't have a boost gauge. :ohsnap:

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What do I hook a boost gauge to if I get one? :hiding:

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:doh2:

[68fastback]

If I recall, this was a very large procharger ...capable of big boost. Did you therefore go with a large pulley to scale it down? Is it possible that it's making 8# by 5500 rpm or so and then 'riding' the blow-off eratically above that? In a higher gear when revs come up slower it may feel fine but in a lower gear under certain conditions (fast rev-up to 5500+) you're feeling the blow-off quickly vent boost and it feels like it's nosing-over ...because it is? Dunno, just wondering if nothing's 'wrong' but in a lower gear when boost is vented it might not be smooth.

Jim/George, are those types of valves designed to accurately hold a preset-boost level (i.e. actually riding 8#)? Or do they tend to blow-off boost and then 'recover' ...as boost rebuilds?

[Tommy Gun]

If I recall, this was a very large procharger ...capable of big boost. Did you therefore go with a large pulley to scale it down? Is it possible that it's making 8# by 5500 rpm or so and then 'riding' the blow-off eratically above that? In a higher gear when revs come up slower it may feel fine but in a lower gear under certain conditions (fast rev-up to 5500+) you're feeling the blow-off quickly vent boost and it feels like it's nosing-over ...because it is? Dunno, just wondering if nothing's 'wrong' but in a lower gear when boost is vented it might not be smooth.

Jim/George, are those types of valves designed to accurately hold a preset-boost level (i.e. actually riding 8#)? Or do they tend to blow-off boost and then 'recover' ...as boost rebuilds?


Yes, big S/C should be on a 1000 hp car. It has the largest pulley we can physically fit on it. Procharger claims it to be the 8-10 lb pulley.

When I was coming into a long straight I would wind it up to 6000 rpm then shift quick and wind it up again w/ no problems. Now when I was in the shorter straights coming out of the turns I would lift for a moment then gas it...it would wind up around 5500-6000 rpm and feel like it lost 100hp all of the sudden w/ the gas floored and slowly pick back up. I assume for some reason it released boost, just don't know why.

It will be very hard to do these same conditions on the street. Winding up to 5500-6000 rpm, that is why I said I won't be able to do it till back on the track?

I'll check what I can.

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[Birdman]

That's why all the more reason you need to have a boost guage. It will tell the story as to what is taking place...... It should do the same thing in a lower gear as it does in a higher gear rpm wise, so you don't have to drive as fast to check it.....there must be a favorite stretch of road you can test it on somewhere.

[Tommy Gun]

Joe, I need a boost gauge. LOL

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:waiting:



LOL


Checking plugs today finally.....maybe. :grin:

[Joe G]

:doh2:

Which one?

[Tommy Gun]

2002 Mustang


Plugs all look kinda brown?

Not spots, brown.

I got a pic somewhere.

They were between .025 and .035 gap.

I set them all to .028 gap, blasted them, anti seized them, and torqued them.

I'll find the pic later.

[68fastback]

Probably more than you want, TG, but this looks to be a very cool boost gauge and integral boost controller (http://www.aemelectronics.com/tru-boost-boost-controller-gauge-757)with no other software or separate external programming ...the video explains what/how you can set up. By direct management of the waste-gates, the specific pulley size wouild *seem* to not matter beyond determining the maximum potential boost since the duty cycle of the controller manages the actual maximum boost the system will permit ...if I'm reading it right. Anyhow, thought I'd post the link since it might be of general technology interest even if not what you're looking for.

[Tommy Gun]

Will that work w/ my set up?

Is it necessary?

I don't really get what it is doing.

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[68fastback]

I think it's letting you build a system with more boost than you'll use all the time, then you can just set the maximum boost you want for a give application: specific track, street, octane/tune combo, etc.

If the biggest pulley you could fit was producing, let's say 11# and you want to limit it to 8#, you could do that in seconds instead of changing pulleys or messing with pop-off settings ...you can also run on the street at lower boost on 93 and then load a C16 track tune and up the boost to match the tune without having to mess with pulleys or pop-offs. Might be especially usefull for tuning turbos but would seem to be compatible with any push boost, like your Procharger.

Is it necessary? Well, you don't already have it so probably not ...besides, need is such a relative thing :shades: ...I've become good at not needing lots of things. :crutch: (<= I just like him)

[Gr8snkbite]

Probably more than you want, TG, but this looks to be a very cool boost gauge and integral boost controller (http://www.aemelectronics.com/tru-boost-boost-controller-gauge-757)with no other software or separate external programming ...the video explains what/how you can set up. By direct management of the waste-gates, the specific pulley size wouild *seem* to not matter beyond determining the maximum potential boost since the duty cycle of the controller manages the actual maximum boost the system will permit ...if I'm reading it right. Anyhow, thought I'd post the link since it might be of general technology interest even if not what you're looking for.

not for that price....i'll stick with something cheaper..:doh2:

[68fastback]

yeah, I think there'd be no point in having one of those for a post-MAF SC since no pop-offs to manage, but for turbos/centrifugal push SCs it could be usefull.

[Tommy Gun]

I need a basic guage for now to see where I'm at.

Do they make boost guages w/ telltales?(recall) Let you know what you hit?

[68fastback]

I need a basic guage for now to see where I'm at.

Do they make boost guages w/ telltales?(recall) Let you know what you hit?

Yeah there's many out there. Here's examples of mechanical and electronic (in the $65-90 range).

Autometer mechanical (http://www.steeda.com/products/aeroforce_mechanical_boost_vacuum_gauges.php)

Prosport electronic with peak recording (http://www.maperformance.com/prosport-52mm-premium-electronic-boost-gauge-amber-white.html)

...just search on "boost gauge" for many more