Boost question

[edfiero1]

What are the factors which limit boost?
I have an 84 T-Type. I just hooked up an external boost gauge and see that I am getting only 12lbs of boost at WOT.

I have a TurboTweak Chip that says it is 14lbs.

My TPS voltage at WOT is about 4.43.

Should I expect to see the full 14lbs, or is 12 as good as it gets on a hot air car?

 

[No disintegrations]

There are many books which explain this. Very long answer. Long story short you want a high octane. You don't want detonation. Too much boost and you will get the detonation which you don't want.
What fuel are you using?

 

[Wahoo]

With being a hot air car, the turbo compresses the air which heats it up and goes directly into your engine.

Hot air is more easily detonated.

That's why most forced induction cars have intercooler, to cool the compressed air down which makes more power, allows for my boost pressure, and is less likely to detonate.

If you can get E85 locally, that will help a lot with a hot air. My hot air is on e85, I have a TA33 turbo and I run around 22psi of boost. I could run possibly more too.

 

[BRAD_PADGETT]

What are the factors which limit boost?
I have an 84 T-Type. I just hooked up an external boost gauge and see that I am getting only 12lbs of boost at WOT.

I have a TurboTweak Chip that says it is 14lbs.

My TPS voltage at WOT is about 4.43.

Should I expect to see the full 14lbs, or is 12 as good as it gets on a hot air car?

This is as good as it gets on a stock hot air. Leave it alone unless you want to blow a head gasket. Higher boost requires race gas, e85 or alky injection or a combination of the three. Start with your homework on the three.

 

[Mike Horak]

This is as good as it gets on a stock hot air...........

 

[youngstr]

1985 Hot air. Like brad said "thats as good as it gets on a stock hot air".........if you still want more boost, its gonna cost you some money and some time to do ur homework. Among the things you'll need is and adjustable wastegate rod, your turbotweek chip should have marked on it the lbs of boost and on what octane fuel to run that boost. Also recommended is a scanmaster and a knock guage. There is also the possibility of having to upgrade ur injectors to bigger ones, thats pretty much where it starts to get expensive. Your turbotweek chip should also have a number on it, you can go to the turbotweek forum and post your chip number and someone there should be able to tell you exactly what that chip requires to run that boost level. Above all do your homework, it only take a few seconds of knock and then you'll here a pop (Head gasket) or u could hear something worse. you have to be very careful when you turn up the boost on hot airs.

 

[edfiero1]

1985 Hot air. Like brad said "thats as good as it gets on a stock hot air".........if you still want more boost, its gonna cost you some money and some time to do ur homework. Among the things you'll need is and adjustable wastegate rod, your turbotweek chip should have marked on it the lbs of boost and on what octane fuel to run that boost. Also recommended is a scanmaster and a knock guage. There is also the possibility of having to upgrade ur injectors to bigger ones, thats pretty much where it starts to get expensive. Your turbotweek chip should also have a number on it, you can go to the turbotweek forum and post your chip number and someone there should be able to tell you exactly what that chip requires to run that boost level. Above all do your homework, it only take a few seconds of knock and then you'll here a pop (Head gasket) or u could hear something worse. you have to be very careful when you turn up the boost on hot airs.

I do have upgraded injectors and fuel pump, and the turbotweak chip says 91 octane and 14lbs. So, I would expect to see 14 on my boost gauge. Since its not going over 12, I was trying to understand what might be holding me back

 

[626gn]

The chip does not "set" your boost at any specific number. It just provides enough fuel to run (in your case with current chip) 14lbs of boost.

 

[BRAD_PADGETT]

I do have upgraded injectors and fuel pump, and the turbotweak chip says 91 octane and 14lbs. So, I would expect to see 14 on my boost gauge. Since its not going over 12, I was trying to understand what might be holding me back

Boost is set by the length of the waste gate actuator rod. This rod is not adjustable be design because of the limitations of the fuel, fuel delivery and intake temperatures. You are at 12lbs boost and are not going higher.

The way around this is to install and adjustable waste gate actuator. This allows you to shorten the length of the actuator rod thereby increasing boost. Your modifications cannot support higher boost without alky injection or conversion to e85. I tried increasing boost with your current modifications and blew the passenger side head 1/8 inch off the block. Not a very smart idea.

 

[youngstr]

Look at your wastegate actuator , the rod that hooks to the waste gate flapper, if it is one solid rod, then u have a stock waste gate actuator. If it is two pieces, one threaded with a lock nut, then you should be able to spin the end of the rod and shorten or lengthen the rod, thats an adjustable waste gate actuator. which one do you have?

If you have an adjustable waste gate, you gotta be very careful, only shorten it one half turn at a time then test it by rolling into throttle getting to wot gradually, any knock you gotta immediately lift off throttle, and access the chip to adjust your fuel targets. Depending on the version of the TT chip it should give you access to adding fuel, and adjusting spark, best plan is to go to turbotweeks website and download instructions for tuning with that chip. please tell me you have a knock guage or a scanmaster, cause you need something to alert you when you have knock and something to keep an eye on your O2 sensor readings so you don't go lean.

I hope this info helps but don't take it as a "how to" you need to check your waste gate actuator, and go to turbotweeks website and download or copy the tuning instructions for that chip, it should have a version # on it 5.x or 6.x the instructions will tell you how to access the chips adjustable features. I highly recommend you do not turn up the boost until you get the chip instructions and understand how to go into the chip and adjust the settings, oh and i'm pretty sure you need a scanmaster to do that so you can see the settings. I told you if you want to raise the boost to 14 or more its proabably gonna cost some money, and some stuff gets expensive love my buick but it is a money pit.

 

[hotairgnx548]

I do have upgraded injectors and fuel pump, and the turbotweak chip says 91 octane and 14lbs. So, I would expect to see 14 on my boost gauge. Since its not going over 12, I was trying to understand what might be holding me back

what does upgraded injectors mean? list what you actually have . are your injectors matched to your chip? most hot air cars when new 13/14 psi before being fooled with.good

 

[crashedout1]

You can also get a boost controller so you can control the amount of vacuum the waste gate sees but you better put some race gas in it and bump that fuel pressure or gamble.

 

[edfiero1]

what does upgraded injectors mean? list what you actually have . are your injectors matched to your chip? most hot air cars when new 13/14 psi before being fooled with.good

42lb injectors - yes matched to the chip.
Also have 87 - ECU, COIL and MAF.
Stock, non adjustable actuator.