Should I hit full boost in 1st...

[cHz]

When at the track or just testing my boost? I turn it up to about 20 for the track and then in 1st gear I'll only hit like 12lbs, then 16 in 2nd and then I'll finally hit 20 in 3rd. Is that supposed to happen, or should I be hitting full boost in every gear before redline?


And is there any difference in building boost between an auto and standard?

 

[Dream On]

Every gear. Sounds like creep or spike to me.

 

[JayRolla]

Well if it was creep the turbo would not stop at 20 it would creep past and if it was spike he would hit over his set amount and finally settle back down. Sounds like a boost leak to me, your losing a lot of spool time. At what RPM do you hit 20 in 3rd?

 

[NewTurboTuner]

I don't
When I run 19psi max. I hit about 17psi in 1st, and after that, I hit full boost in all gears.

Even though Redline is 7000rpm. With stock cams, the power falls off fast after 5500rpm. The hard acceleration is at lower RPMs (3000-5500) ...that's where the stock engine is under the most load, and it accelerates the hardest. When the power falls off real quick after 5500 ...The engine isn't under as much load. And the less amount of load the engine sees... the less boost you get.

1st gear in our cars is over so quick... especially with stock cams, and the power falling off so quickly after 5500rpm. Think about it... the good power range with a stock cams car is 3000-5500 ...and in 1st gear that is over very quick(maybe 1 second?) 1 second is barley enough time to go from 0-20psi, if at all. Even 2nd gear can be over real fast. Occasionally I wont see 100% boost in 2nd, but not too often. That's why people say do a 3rd gear pull ...because with the longer gear... the engine is held between 3000-5500rpm alot longer, and that's where the load is at.

A after market cam would help our cars sooo much. It would extend the power range further than 5500.... like 6800-7400RPM ....that way your power doesn't fall off... it keep pulling hard up to 7400. You would surely see 100% boost in 1st if you had some cams. Head/Cams are my next mod

hope that helps!

 

[nightspeed87]

You have a point but it also depends on the turbo and the set up...
If you have a big turbo with a lot of lag then this validates, but on 14b and 16g
with all the proper intake tract upgrades, porting, and full exhaust you should still be able to reach your boost by redline if you have no leaks. If you have a leak then yea you wont see it .. Well let me not speak for the 16g since i dont have one, but I could see full boost on my 14b every gear if everything running right. ( But ive never boosted at 20 lbs either so maybe thats why.)

 

[Armours]

I told you to take your wastegate hose off and just don't boost it past 20

 

[oldman]

I told you to take your wastegate hose off and just don't boost it past 20

One of the worst advice ever! This would be a very quick way to an engine rebuilt, you do realize that you can hitting full boost with as little as 50% throttle and that it will take less than a split second to go from 20 to 25psi right?

 

[JayRolla]

cant believe he said to do that.

 

[dieseltech]

I don't
When I run 19psi max. I hit about 17psi in 1st, and after that, I hit full boost in all gears.

Even though Redline is 7000rpm. With stock cams, the power falls off fast after 5500rpm. The hard acceleration is at lower RPMs (3000-5500) ...that's where the stock engine is under the most load, and it accelerates the hardest. When the power falls off real quick after 5500 ...The engine isn't under as much load. And the less amount of load the engine sees... the less boost you get.

1st gear in our cars is over so quick... especially with stock cams, and the power falling off so quickly after 5500rpm. Think about it... the good power range with a stock cams car is 3000-5500 ...and in 1st gear that is over very quick(maybe 1 second?) 1 second is barley enough time to go from 0-20psi, if at all. Even 2nd gear can be over real fast. Occasionally I wont see 100% boost in 2nd, but not too often. That's why people say do a 3rd gear pull ...because with the longer gear... the engine is held between 3000-5500rpm alot longer, and that's where the load is at.

A after market cam would help our cars sooo much. It would extend the power range further than 5500.... like 6800-7400RPM ....that way your power doesn't fall off... it keep pulling hard up to 7400. You would surely see 100% boost in 1st if you had some cams. Head/Cams are my next mod

hope that helps!

I agree with you. There is a simple relationship to remember. More load=More Fuel=More Boost. When testdriving vehicles with turbos and comparing that experience with your issue it seems normal. If you want more boost at a higher rpm you need to open the intake and clear the exhaust. If you want it at a lower rpm try a BB turbo or get more fuel to provide more exhaust volume.

 

[andymoraitis]

I can verify the same results. On a 50 trim with the Tial shimmed and springs installed, I hit 22 psi in first, 24 in second and 25 in every gear after that. The gearing takes a lot of load off of the motor in the lower gears and once that load is present, full boost (in the absence of leaks) becomes realized.

For the original poster, you're seeing a lot more variance than the norm.

Just my .02,

Andy

 

[andymoraitis]

You would surely see 100% boost in 1st if you had some cams. Head/Cams are my next mod.

I have aftermarket cams and I don't see full boost in 1st gear. The time duration and load on the motor are so low that it's impossible. Maybe if I revved to 8500K I might, but not with a turbo that spools fully at a bit over 4200. Advancing the intake cam slightly or leaning the A/F's at the onset of boost will help me spool faster though and that might give me a bit more boost in first.

The rest of your post is dead on though.

 

[Armours]

One of the worst advice ever! This would be a very quick way to an engine rebuilt, you do realize that you can hitting full boost with as little as 50% throttle and that it will take less than a split second to go from 20 to 25psi right?

you do realize hes only hitting 12 psi so is his wastegate is probalby messed up

He also has a rigged mbc made from fishtanks valves

So if you are smart about it nothing will happen

 

[oldman]

you do realize hes only hitting 12 psi so is his wastegate is probalby messed up

He also has a rigged mbc made from fishtanks valves

So if you are smart about it nothing will happen

Ok smart guy, please explain how can a wastegate be defective as to cause 12psi only in 1st gear? (in detail, no more one liners) Further more for shits and giggles, let's pretend that he is getting 12psi in every gear no matter what the mbc setting is, the only way a wastegate can be blamed for this is that it's being blown open by exhaust pressure, so how is removing the intake pressure signal to the actuator going to prevent this? (again in detail)

We don't take mis-information too kindly around here, please make your response an intelligent one or retract your previous statement. There are so many things which can go wrong trying to use your foot as a MANUAL boost controller, the only way you can be "smart about it" is to not do it period.

 

[spyderturbo007]

you do realize hes only hitting 12 psi so is his wastegate is probalby messed up

He also has a rigged mbc made from fishtanks valves

So if you are smart about it nothing will happen

I would be very careful proceeding with this thread. Oldman is a VERY respected member of this board and no one here will tolerate you attempting to degrade any of the members. You have already posted misinformation in this thread, which is a giant "no no" here, so you might want to stop while you are ahead. This quote is straight from the "Rep Points System" sticky.

Insulting a Wiseman will not be tolerated. If you have a problem with a Wisemans' post, Report the post to a Moderator. Do not get into a pissing match with them publicly. They volunteer their time to help inexperienced members on our site and will not be hassled or subjected to ridicule by members who have made fewer contributions to the site than they have.

I just want to warn you before you get yourself in trouble.