Dern lackaboost

[ChrisCairns]

For those of you who didn't read my report on Vegas, I couldn't raise the boost over 21.7 psi according to FAST with the new 88 turbo. John Craig suggested that perhaps my acetylene regulator, which I use for a boost controller wouldn't allow more than 15 psi through it.

Last night I removed the acetylene regulator and put 50 psi into the inlet from my regulated air compressor. Exactly 50psi came out (attached to a pressure gauge) with the regulator totally cranked down so it isn't my regulator. (And I was able to cut the pressure to zero by turning the knob all the way up).

Using the single brain cell I have left I thought about the following and would like some input from you smart yet somewhat ugly people....(I wonder if anyone will answer...lol).

Let's assume my turbo compressor is putting out 25 psi into the boost control line. This boost control line is then split, one side going directly to the underside of the Racegate diaphram. The other leg goes into the acetylene regulator and then back to the top of the Racegate diaphram. If I have 25 psi to the bottom trying to lift the diaphram and the same 25 psi (with the acetylene regulator totally cranked down) to the top of the gate then with this boost pressure the diaphram is at a neutral level. The only thing holding the valve in the gate shut is the spring. The valve would only open once the backpressure in the header which is pushing on the valve face equalled the spring pressure.

Does this make sense?

And should I just run the boost line from the acetylene regulator to the top of the diaphram with the bottom port open thereby allowing the spring and whatever pressure I allow through the regulator to control the gate?

Any insight would be appreciated.

 

[EightSecV6]

Originally posted by ChrisCairns
[
And should I just run the boost line from the acetylene regulator to the top of the diaphram with the bottom port open thereby allowing the spring and whatever pressure I allow through the regulator to control the gate?

Any insight would be appreciated. [/B]

DONT do that, your thinking is absolutely correct, however if you remove the hose from the bottom and leave it to the top is will overboost, not getting too technical but the diameter of the diaphragm even at a lower pressure will create more downward force than the valve can create upward even with more (back) pressure on it.
You need to leave everything as it is and have Turbonetics send you a BLACK spring and ceank the adjusting screw in until it is about 2 threads below the lock nut. Should be capable of netting OVER 30psi at this setting, we went through the same crap in the past.
Bill


P.S. Try to crank the adjusting screw in 2 threads below the lock nut now and you shoud get about 3-4 more # of boost with the spring you have.

 

[ChrisCairns]

Thanks very much Bill.

I'll get the spring....hell I may even have it in my pile of spare parts since I have a few of Turbonetic's springs.

And something ironic about the set screw .... after I put on the bigger turbo I "unscrewed" the screw, not wanting to worry about too much boost....lol. I never even thought about screwing it back in while in Vegas.

Damn it, will you people PLEASE stop me from working on these cars !!

 

[geno]

Hey Chris
Ive disconnected mine and set my air compresor regulator to 25# and hooked the hoses up to a T and watched mine while turning the boost knob up and down. I wanted to know how early the wastegate started to creap opened Just something to try without driving the car. I think you guys have snow over there and not much chance to do a test run This way you can get a feel if things are working right without leaving garage..
Just something you might want to try to help track down your problem and is a good way to check for air leaks in the wastegate too because they do need to be rebuilt sometimes..
When they leak they have a hard time holding a steady boost and not the problem you have.

 

[ChrisCairns]

>>Originally posted by geno
>>Hey Chris
>> Just something to try without driving the car.

I'll try that. I did it once before just like you described but haven't done it since. You may be onto something as I phoned John Craig a few days ago (talked to Chopper instead)....I just to tell him I wasn't going to send the turbo back until I've had a chance to try it with the bigger spring just in case it is my Racegate. Chopper asked me if I'd had the gate apart. I said sure and he went on to say that I may have pinched part of the diaphram when I reassembled it. Ya never know. So I'll try what you suggest.

>>I think you guys have snow over there and not much chance to do a test run

Snow? Snow? Oh, that really hard rain

Nope, we don't have any yet but I don't take the car on the street anyway. I'm in a small town and the local gendarmes would spot it in an instant. I'm too old to beg for mercy from some judge 30 years younger than me....lol.

 

[Reginald West]

Chris
Just so you know that your the only guy having this problem.I am going through the same thing with the new 80 turbo that I installed. The Race Gate won't allow over 20 lbs of boost I have been talking to turbonetics for three days about the problem they have finally arrived at the conclusion that its the Race Gate they are shipping a new one.I will let you know if it solves the problem.



REG

 

[ChrisCairns]

Originally posted by Reginald West
Chris
Just so you know that your the only guy having this problem.I am going through the same thing with the new 80 turbo that I installed. The Race Gate won't allow over 20 lbs of boost I have been talking to turbonetics for three days about the problem they have finally arrived at the conclusion that its the Race Gate they are shipping a new one.I will let you know if it solves the problem.



REG

Hi Reg,

It was good to meet you Vegas....thanks for sending that hooker to my room. Hope you didn't pay too much for her though...she was really ugly. Plus she wasn't too bright as she put the bag over MY head instead of over her own.

Keep us all posted...I for one am interested in the results. I have another Racegate on another car I could switch over if you find your first gate was bad.

 

[Reginald West]

Chris
Consider the hooker a gift from one OLD MAN to another.Maybe next year we both do alittle better at the track.

I will keep you posted about the gate.

REG

 

[EightSecV6]

Reginald,
What color spring is in yours?
Bill Anderson

 

[Reginald West]

Bill
I don't know right off hand what color it is but I will look tonight and post. Turbonetics tells me that they only use one spring now.
I am susposed to be getting a new gate this afternoon maybe I will know a little more then.


REG

 

[Reginald West]

Bill and Chris

Bill the spring is black.

Chris, I got the new gate and installed it. Same problem dumps at 20 PSI. I called Jack Cotton he says its back pressure that is causing the problem. With that said he ordered another spring to go with the black one I have (2 springs).I am going to the track tomarrow. A friend is bring some extra springs so we are going to do a little testing with 2 springs. I will let you know how it works out.

REG

 

[TurboDiverArt]

Originally posted by Reginald West
Chris
Just so you know that your the only guy having this problem.I am going through the same thing with the new 80 turbo that I installed. The Race Gate won't allow over 20 lbs of boost I have been talking to turbonetics for three days about the problem they have finally arrived at the conclusion that its the Race Gate they are shipping a new one.I will let you know if it solves the problem.



REG

I had just the opposite problem, too much boost. My gate use to be really far out (probably at least 4-5 threads above the lock nut) and would net about 23 psi with the knob cranked fairly tight. In Bristol I couldn't get more than 20 psi boost regardless how much tighter I cranked the knob so I started cranking in the spring in the gate. Ended up cranking it level with the lock nut, only had marginal effects in Bristol. Come to find out that I had exhaust leaks all over the place. When I came back home to the "good air" I cranked my boost controller knob back out 3 turns and on my first launch I let off when the boost rocketed to 29 psi (oops). Probably where I weakened the head gasket which went on my last run of the season.

 

[ChrisCairns]

Originally posted by Reginald West
Bill and Chris

Bill the spring is black.

Chris, I got the new gate and installed it. Same problem dumps at 20 PSI. I called Jack Cotton he says its back pressure that is causing the problem. With that said he ordered another spring to go with the black one I have (2 springs).I am going to the track tomarrow. A friend is bring some extra springs so we are going to do a little testing with 2 springs. I will let you know how it works out.

REG

Yep...let us know. I'm also interested in how the hell you're going to fit 2 springs in there....lol.

 

[TurboDiverArt]

Originally posted by ChrisCairns
Yep...let us know. I'm also interested in how the hell you're going to fit 2 springs in there....lol.

Duct tape and a really big hammer? Sorry, it was just hanging out there.....

 

[EightSecV6]

Originally posted by Reginald West
Bill and Chris

Bill the spring is black.

Chris, I got the new gate and installed it. Same problem dumps at 20 PSI. I called Jack Cotton he says its back pressure that is causing the problem. With that said he ordered another spring to go with the black one I have (2 springs).I am going to the track tomarrow. A friend is bring some extra springs so we are going to do a little testing with 2 springs. I will let you know how it works out.

REG

Correct on the back pressure REG, I stated that in my first post on this topic...
What is the A/R on the exh hsg? The black spring is enough to get the job done. Are you running a Q-trim? You could probably band-aid it with an additional (inner) spring but sounds to me like you are moving too much air for the exh hsg/wheel combo you are using.May not go any faster with more boost in this situation due to excessive back pressure. Be sure to post your results
Good luck,
Bill Anderson

 

[Reginald West]

Bill
A/R is 81 Q trim with 80 Ball Bearing Turbo.


REG

 

[TurboDiverArt]

Originally posted by EightSecV6
Correct on the back pressure REG, I stated that in my first post on this topic...
What is the A/R on the exh hsg? The black spring is enough to get the job done. Are you running a Q-trim? You could probably band-aid it with an additional (inner) spring but sounds to me like you are moving too much air for the exh hsg/wheel combo you are using.May not go any faster with more boost in this situation due to excessive back pressure. Be sure to post your results
Good luck,
Bill Anderson

Bill,

Would having a bigger or smaller A/R help this situation. I'd assume having a larger A/R would cause less back pressure since it flows more?

Thanks in advance for the info,

 

[ChrisCairns]

Interesting that you should comment about the housing Bill.

I was talking to a person in Las Vegas (who prefers to remain nameless) and he said he measured his backpressure when he was running 22 psi. He had 55 psi of back pressure. (He then converted to a humongous PTE exhaust housing). He went on to say that it's the exhaust housing and wheel that's holding a lot of people back and that a larger compressor wheel wouldn't do any good since it's the backpressure that's the culprit.

What this guy said to me made a big impression on my lil brain....and when I talked with John Craig I specifically asked him what he thought about that. He replied that with mine (.96 A/R) he didn't think that's what was limiting my boost.

So apparently smaller exhaust housings do limit boost, albeit indirectly.

 

[TurboDiverArt]

Originally posted by ChrisCairns
Interesting that you should comment about the housing Bill.

I was talking to a person in Las Vegas (who prefers to remain nameless) and he said he measured his backpressure when he was running 22 psi. He had 55 psi of back pressure. (He then converted to a humongous PTE exhaust housing). He went on to say that it's the exhaust housing and wheel that's holding a lot of people back and that a larger compressor wheel wouldn't do any good since it's the backpressure that's the culprit.

What this guy said to me made a big impression on my lil brain....and when I talked with John Craig I specifically asked him what he thought about that. He replied that with mine (.96 A/R) he didn't think that's what was limiting my boost.

So apparently smaller exhaust housings do limit boost, albeit indirectly.

zx

 

[TurboDiverArt]

Originally posted by ChrisCairns
Interesting that you should comment about the housing Bill.

I was talking to a person in Las Vegas (who prefers to remain nameless) and he said he measured his backpressure when he was running 22 psi. He had 55 psi of back pressure. (He then converted to a humongous PTE exhaust housing). He went on to say that it's the exhaust housing and wheel that's holding a lot of people back and that a larger compressor wheel wouldn't do any good since it's the backpressure that's the culprit.

What this guy said to me made a big impression on my lil brain....and when I talked with John Craig I specifically asked him what he thought about that. He replied that with mine (.96 A/R) he didn't think that's what was limiting my boost.

So apparently smaller exhaust housings do limit boost, albeit indirectly.

Oops, meant to post this!

Chris,

Did the mystery guy in Las Vegas say the increasing the A/R would decrease backpressure or is the only solution getting one of those monstrous PTE 88 housings?