F.i.c

Well i got some work done to my car. One of those things was a fuel injection cleaning. Its suposed to get of all the carbon and what not in your engine. Anyway I got that done and it smokes when you rev the engine but thats normal. It smoked in side the engine and thats not. I think i have a crack in the exhaust manifold. But after all of that my turbo starts to spool up at 3k instead of 4krpms. So for anyone who hasnt had this done i recomend it highly.

You should spool a lot before 3k with the 14B.

I'm not trying to ruin your parade, but your car definitely has some more issues.

Yeah, I've heard that removing all the carbon can unclog little cracks that wouldn't be an issue otherwise. Just keep an eye on everything. Best of luck! :cheers:

You should spool a lot before 3k with the 14B.

I'm not trying to ruin your parade, but your car definitely has some more issues.
Do you mean start to spool, or get to full boost?

yes i start to spool at three but it doesn't kick in until 4k

Definetly something wrong there... Maybe you have a large boost leak also? It should start spooling almost immediatly.You said it smokes in the engine bay too? Maybe that is also a problem, you may not have enough back pressure to spool the turbo like it should... I'd definetly check for cracks in your manifold and check for boost leaks.

Yup, sounds like exhaust manifold cracks or broken studs. Can you hear an exhaust leak there?

it is diff the exhaust manifold.... or the gasket from manifold to turbo is bad.... it has nothing to do with back pressure though =) i thought that turbo cars don't need back pressure but i could be wrong

it is diff the exhaust manifold.... or the gasket from manifold to turbo is bad.... it has nothing to do with back pressure though =) i thought that turbo cars don't need back pressure but i could be wrong

They do like wide open exhausts, but they do need some back pressure to run good... I'm pretty sure this is how it goes, but someone correct me if I'm wrong... I think it has something to do with velocity, as you funnel air into a smaller opening it moves faster and the bigger the opening it moves slower. So you you have like a 1 inch exhaust on a turbo car, then the exhaust gases are gonna be going fast as hell through it and it should spool the turbo quicker if it's a small turbo. If it's a larger turbo then you need more room to push all that air through. It's all some sort of ratio of CFM to exhaust size or something. That's why it IS possible to have too big of an exhaust and it has a harder time spinning the turbine to a larger turbo. But, if your exhaust is too small then it just can't get rid of all that exhaust quick enough... There was a site that explained it all, I'll find it again and post the link up here when I find it.

***EDIT***
Here's the link to that site I was refering to.
http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm

Happy reading! :lol2:

No exhaust leaks in the manifold and all the studs are good for sure. I still have the stock down pipe so i was thinking that might be part of the problem. I drove my friends 1g and his turbo you could feel kick in at 3 and his car is completely stock. When i hit boost mine has more power than his but as far as spool time goes his is for sure faster.

If its smoking in the engine bay then there has to be something cracked or leaking... Having the stock downpipe shouldn't be a factor because I still have mine too and its fine... If your sure there are no manifold leaks then I'd go onto checking for boost leaks.

its not smoking in the engine bay. that happend after i did it but it was the smoke comming from the bottom of the car back into the engine. thats what we determinded. It happens on all of the turbo cars that we do for some odd reason. Even the brand new ones that do it they smoke there.

The exhaust manifold has been checked since then.
Would the stock intercooler piping affect it also?

The stock intercooler piping shouldn't affect it unless its leaking... If anything, it should make it spool sooner with smaller piping like that.

well I'm out of ideas here. Theres no smoke. And it spools just fine when its 30 degrees outside but i live in texas thats not normal weather around here.

Turbo cars do NOT need backpressure. You're thinking of n/a. It's been said many times: No exahust is the best exhaust. That's why people run just a giant tube from the turbo straight out the side of the front bumper. Also, I believe it's the pressure diferential (before turine/after) that spins it, along with heat. The bigger the differential the faster it spins. Someone correct me if I'm wrong.

Turbo cars do NOT need backpressure. You're thinking of n/a. It's been said many times: No exahust is the best exhaust. That's why people run just a giant tube from the turbo straight out the side of the front bumper. Also, I believe it's the pressure diferential (before turine/after) that spins it, along with heat. The bigger the differential the faster it spins. Someone correct me if I'm wrong.

If you read that link I posted, it makes it sound like some backpressure is necessary. I suppose there are a billion different possibilitys though.

That info is from an NSX forum though. Not the biggest turbo info source. They even say 'if you have a turbo we envy you.'

Turbos do not need back-pressure, a turbo works by moving air from high pressure to low pressure which in turn spools the turbo. maybe runners before the turbo but not after it,

But if the exhaust is too big then exhaust gases cool down and become dense and then the turbo has to work that much harder to push the gases out of the system. But if you keep too small of an exhaust then your turbo can't push it out fast enough... I know it was from an NSX forum but all the basic physics of it still apply whether its a turbo car or not. The only time you don't have to worry about it is when you aren't running a full exhaust. But for most of us, that isn't an option...

I've posted about this before, the long version should be in the archives. To make it as short as possible, the exhaust will always be much less of a restriction than the turbine section, so it's pretty much irrelevant as far as how the motor "runs." Whoever posted that the pressure differential across the turbine contributes to the energy used to do work is correct, I covered that recently in the load dependent stuff post, forget what thread it was though.

Edit> To add to that, no motor needs backpressure to run properly. However, NA motors are sensitive to exhaust tuning, affected by the scavenging effect, which depends on exhaust gas velocity and cylinder to cylinder pulse timing. The restriction provided by the turbo right after the head pretty much throws a monkey wrench into this whole system, no longer applies.