Gt 2871r boost help

Zans

Registered User
Hello. I am currently fitting a gt2871r in my APY engine. For the moment my engine isn't rebuilt and uses stock rods. I want to drive it for the moment so need to control boost to match it with the stock k04, do i install a boost controler or the n75j valve will do it for me? What is the stock boost for the k04 on APY engine? Is it possible to reprogram the n75 so it's used as boost controler?


If anyone is wondering why i still haven't rebuilt it to support this kind of power is because my k04 is leaking a lot of oil and needed a quick turbo change.. a friend of mine sold me a nice gt2871r for a good price because i planned on doing that anyways after the rebuild.

Sent from my SM-J730F using Tapatalk
 

<tuffty/>

Badger 5 Edition...Its all about the flow...
Staff member
Moderator
It will need mapping to ensure fuelling is correct especially on a narrow band ecu like your APY has

I assume you haven't fitted injectors either... Which you will need to do to be honest...

You can map the gt28 safely (will be less boost than the K04) but the ecu will be blind to AFR when on load and you stand a chance of leaning out the engine... which would not end well...

<tuffty/>
 

Zans

Registered User
It will need mapping to ensure fuelling is correct especially on a narrow band ecu like your APY has

I assume you haven't fitted injectors either... Which you will need to do to be honest...

You can map the gt28 safely (will be less boost than the K04) but the ecu will be blind to AFR when on load and you stand a chance of leaning out the engine... which would not end well...

<tuffty/>
Thanks for the reply. I already have new bosch 630cc injectors but still haven't fitted them, do i need to fit them before rebuilding the engine or after? Will a boost controller limited to k04 boost will do the job right?
 

<tuffty/>

Badger 5 Edition...Its all about the flow...
Staff member
Moderator
Thanks for the reply. I already have new bosch 630cc injectors but still haven't fitted them, do i need to fit them before rebuilding the engine or after? Will a boost controller limited to k04 boost will do the job right?
Depends what you mean by 'K04 boost'... remember... boost is just a facilitator... its a measure of restriction not airflow...

A GT2871 will flow more air for the same boost than a K04... so to get the right/safe airflow you would actually need less boost not the same boost...

This also depends on what the actuator is rated at... std K04 is 0.5bar so thats the least amount of boost it can produce... if your GT2871 also has a 0.5bar actuator then it will flow more air and therefore make more power and require more fuel than the K04..

If the GT2871 has at least a 1bar actuator then you will be running std full boost levels (std K04 on full boost is around 12psi)... at this point you will be running more airflow than the K04 does which means more fuel/load...

Its at this point that narrow band ecu's can struggle... its plausible that the MAF will see airflow in its mapped range and be able to cope but this is not a given and without having it at least run on a dyno to check fueling with a wideband lambda then your engine could potentially melt itself...

Fitting the 630's won't help either as when the ECU can see fuel it won't know they are 630's and adapt to pull fuel out... it will run rich as anything and could lead to bore wash if not addressed..

Basically... you just need to get the car tuned...

<tuffty/>
 

Zans

Registered User
Depends what you mean by 'K04 boost'... remember... boost is just a facilitator... its a measure of restriction not airflow...

A GT2871 will flow more air for the same boost than a K04... so to get the right/safe airflow you would actually need less boost not the same boost...

This also depends on what the actuator is rated at... std K04 is 0.5bar so thats the least amount of boost it can produce... if your GT2871 also has a 0.5bar actuator then it will flow more air and therefore make more power and require more fuel than the K04..

If the GT2871 has at least a 1bar actuator then you will be running std full boost levels (std K04 on full boost is around 12psi)... at this point you will be running more airflow than the K04 does which means more fuel/load...

Its at this point that narrow band ecu's can struggle... its plausible that the MAF will see airflow in its mapped range and be able to cope but this is not a given and without having it at least run on a dyno to check fueling with a wideband lambda then your engine could potentially melt itself...

Fitting the 630's won't help either as when the ECU can see fuel it won't know they are 630's and adapt to pull fuel out... it will run rich as anything and could lead to bore wash if not addressed..

Basically... you just need to get the car tuned...

<tuffty/>


Thanks for the reply. I understand that i need to get it tuned but i still need to make a trip between my garage and the tuner.. so i thought restricting boost would make the car not blow the rods. So what can i do in my garage to safely make the trip (+/- 350km)?
 

<tuffty/>

Badger 5 Edition...Its all about the flow...
Staff member
Moderator
If you drive part throttle with N75 unplugged and short shift keeping revs low then you should be fine... Just don't be tempted to put your foot down and rev out the engine

<tuffty/>
 
Top