What is the opposite of boost creep?

[98GSXin]

Hi again. I've recently been toying around with my MBC to try and find a sweet spot for daily driving. First I cranked it up all the way just for kicks and got fuel cut. Obviously that was a no go, so I've been dialing it back slowly until I get no more fuel cut. Thing is, I have eliminated the fuel cut and have the boost peaking around 17-18 and then dropping slowly like the opposite of boost creep. I know that a boost leak is a possibility, and I plan on running a check soon, but why can't it hold a consistent pressure anything higher than 15? Mod list is current.

I know running my stock fuel system and stock t25 on higher boost without any support is a , but I am basically asking for an excuse to swap my turbo. Kinda hoping it blows.

 

[cookmeup272]

T25's do blow. All turbos will spike and then settle down. Turbos have efficiency ranges where they can flow the most amount of air. As you go through the revs, you will build boost and spike then settle down a couple of psi on the higher rpms.

 

[Oliver@Slowboy]

That is your turbo feeling like a fat kid with asthma running up hill.

Time to upgrade.

Oliver

 

[slickers111]

Boost Creep-Boost Rising above the set PSI.
Boost Leak. Not being able to hit full boost.

 

[98GSXin]

Boost Creep-Boost Rising above the set PSI.
Boost Leak. Not being able to hit full boost.

How will I know I am hitting full boost? Is it the 17-18 it spikes at or is the 15 really the full boost?

That is your turbo feeling like a fat kid with asthma running up hill.
Oliver

So I am basically going to give my fat kid a heart attack, and then rebuild him faster, better and stronger because "we have the technology". I kind of like the thought of having a fat kid hopped up on steroids and robot parts.

T25's do blow. All turbos will spike and then settle down. Turbos have efficiency ranges where they can flow the most amount of air. As you go through the revs, you will build boost and spike then settle down a couple of psi on the higher rpms.

So basically this is normal is what you're saying? I was expecting to see it build to a set value and maintain that value. Do all turbos spike like this or is it just the extra stress I'm putting on it?

 

[cookmeup272]

Its especially seen in smaller turbos. It doesnt happen on my 50 trim really because im only boosting it to about 20psi right now. Before i had it set at 26. If I was to set it at say 28, i would expect it to spike and then drop to say about 25-26 at redline

 

[JDog_27]

That is your turbo feeling like a fat kid with asthma running up hill.

Time to upgrade.

Oliver

This gave me a good laugh!

 

[dsmdeliveryboy]

Your gonna be giving yourself a reason to get a no motor too if you keep testing the waters like that, get rid of that t25 and get a 14b and mod your car correctly with supporting mods or something to log with or don't mod it.

 

[98GSXin]

Your gonna be giving yourself a reason to get a no motor too if you keep testing the waters like that, get rid of that t25 and get a 14b and mod your car correctly with supporting mods or something to log with or don't mod it.

A 14b is only a small upgrade... and I actually plan on rebuilding everything from the ground up. The car has had 4 owners and I have no idea what it's been through in the past. So it's like a little science project right now. I plan on rebuilding the head and block both separately, depending on which goes first... That way I know that it will be healthy. I'm not a quitter and I plan on dropping probably too much money into this baby. I am just having a bit of fun and getting the most bang for my buck while I can in the meantime. Is that so wrong?

 

[Jonman409]

I was never able to hold above 15lbs on my stock 2g bov. If you have that, swap it out.

I was never able to hold above 15lbs on my stock 2g bov. If you have that, swap it out.

NVM, sorry I looked up your mods after I posted this.

 

[colbyc]

Yes that is wrong, unless you have another dd or something and can afford to screw up engines.

 

[98GSXin]

Yes that is wrong, unless you have another dd or something and can afford to screw up engines.

Of course I have another car lined up to drive. I'm not trying to shoot myself in the foot. Is it really that unheard of to drive a car into the ground before you build it up like a phoenix rising from the ashes? haha.

 

[colbyc]

Well no, I just dont know why you'd risk damaging something thats perfectley fine set it at 15 psi. I wouldn't go any higher than that on the t25. And atleast get some kinda fuel mods wally 190 and evo 560's might set you back 250-300.

 

[dsmdeliveryboy]

Well no, I just dont know why you'd risk damaging something thats perfectley fine set it at 15 psi. I wouldn't go any higher than that on the t25. And atleast get some kinda fuel mods wally 190 and evo 560's might set you back 250-300.

I'm with you on this

 

[98GSXin]

Because I don't know what has been done to the car in it's past. It's not really risking damaging it when it more than likely is already damaged. 4 owners later and evidence in the car that it has been previously modified means for all I know, the pistons are weakened/ ready to give. Or the head gasket is ready to go. I have close to 120k on the car and now it's only a matter of time before something breaks. I might as well break it on my terms and then fix it so that I don't have to live with the anticipation of when it may or may not break.

walbro 190 + 560cc now for 250-300 PLUS walbro 255 + 850cc for 300-400 down the line = 550-700

or

walbro 255 + 850cc later when I'm ready for it/ need it = 300-400

 

[colbyc]

Dude you're looking at it all wrong! How can you say the pistons have "weakend" or the hg is about to blow? Its all how you treat it and maintain it....you sir are not a good dsm owner
And so what if it was previously modded? Its running right now right? Seems to be running strong seeing as how its taking the abuse the YOU"RE throwing at it,
not telling you how to mod/treat your car just saying you might need to rethink a little

Btw just go ahead and get you a 16g if you're looking for an excuse to get a new turbo, they can take your abuse pretty well then you'll have an excuse to get link and some bigger injectors, fpr, and a fuel pump

 

[dsmdeliveryboy]

Or you can run a 16g the same way you are now with that t25 and have a reason to build a new motor even sooner

How can you say that when you haven't done a compression test, leakdown test, or check the crank for play? For all you know the motor could be good. This isn't a Honda..

 

[98GSXin]

.you sir are not a good dsm owner

Said the guy with a fast and furious paint job........

And the compression is 170,155,155,170. It was burning oil when I got it and I have figured it is either the valve stem seals or bad piston rings (which would also explain the compression differences). So while the head is out to get the valve seals I figured 3g lifters and a full rebuild is in order anyways. Then I will tackle the block and re ring it and check for crankshaft play.

So before you guys jump down my throat, maybe try to see it from my position. I am really trying to make my car better and stronger in the long run. I am not treating it like a honda. I am just using up the life in the car I have left and biding my time/money until I can really go all out on it.

 

[colbyc]

You will no longer get help from me, buddy

 

[GSXSixteenG]

So your trying to blow up an engine that has completely fine compression.. If it was abused like you said before you would notice more of a difference in compression. There is plenty of stuff that can lead to the small difference in compression that you are showing. The service limit is 133, I'm sure there are plenty of people on this board driving cars with lower compression than you. But go ahead and blow a fine motor, because these people know nothing..

 

[dsmdeliveryboy]

Probably just your valve seals, but sounds like you know what you wanna do.

 

[Memphetic]

Boost creep is caused when the turbo is pushing more air than the wastegate can get rid of to sustain the pressure level that you've set, usually due to using an internal wastegate that isn't large enough or knockoff external - so, the opposite would be when your turbo can't push ENOUGH air to attain the pressure level you've set (likely caused by a vacuum leak).

 

[98GSXin]

Ok. Did some more playing and I've just about got it right. 1st and 2nd gear pull at full boost everytime. But it's about 50/50 in 3rd gear. Half the time I get fuel cut, half the time I don't. 4th and 5th are fine as well. Why would only one gear suffer from fuel cut?