Arin@APR
GOLFMK7 Official Sponsor
- Location
- Auburn, Al
- Car(s)
- B8 S4, MK7 GSW TDI
We have a car here we can upgrade, we just have to get it scheduled with engineering. Looking like that will happen some time after waterfest next month.
7
APR 1.8T ECU, TCU, IS20, IS38 Upgrades - Up to 350+ HP Now Available!
- Thread starter Arin@APR
- Start date
MeltedSolid
Autocross Newbie
- Location
- San Francisco Bay Area
- Car(s)
- '15 Golf, e36 328i
If anyone does eventually do the IS38 with the 5speed I'll be really curious to hear about how the turbo lag is. It seems the IS38 only really spools at 3300ish rpm on our engines, which based on my experience with the IS20 spooling at 2900rpm might be on the edge of the good usability range, but it is lower than I was fearing. Maybe it will turn out to be a non-issue if we're lucky.
Boost threshold and lag. To related but separate things We know one, but not the other.
We know the boost threshold of the 38 is about 400 rpm later than the 20. But independent of that, how is lag (transient response delay)?
Someone who has done the switch on the GTI must have so me opinions.
Maybe George has some opinions and data.
We know the boost threshold of the 38 is about 400 rpm later than the 20. But independent of that, how is lag (transient response delay)?
Someone who has done the switch on the GTI must have so me opinions.
Maybe George has some opinions and data.
Ironshade
Go Kart Newbie
- Location
- Atlanta Ga
You can rev out to 7k easily with power.. so even a little later spool it'll be no problem just ride a gear a little longer. On a 5MT is38 is perfect. Less down low to cause wheel spin then big up top where if counts. Plus... less low end means lower load on motor so in all honesty you may make more power safer as long as fueling can keep up. I'm is20 right now on the 5mt sportwagen, i'll be doing hpfp and injectors before I go is38 route. Fueling can barely support is20 with fol 75 and other tricks. Apr tune will be good basis to stack ontop of when it comes time
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Arin@APR
GOLFMK7 Official Sponsor
- Location
- Auburn, Al
- Car(s)
- B8 S4, MK7 GSW TDI
This platform has a Bosch pump, which is not internally upgradable like the hitachi unit.
The ECU will not know you've upgraded the injectors, and will not operate correctly. I'd recommend not altering the injectors for this reason.
You can rev out to 7k easily with power.. so even a little later spool it'll be no problem just ride a gear a little longer. On a 5MT is38 is perfect. Less down low to cause wheel spin then big up top where if counts. Plus... less low end means lower load on motor so in all honesty you may make more power safer as long as fueling can keep up. I'm is20 right now on the 5mt sportwagen, i'll be doing hpfp and injectors before I go is38 route. Fueling can barely support is20 with fol 75 and other tricks. Apr tune will be good basis to stack ontop of when it comes time
20 questions time.
Where are you getting fuel pump from? Also, any idea how much bigger the GTI injectors are? Do you think just adding GTI injectors would add headroom without upgrading fuel pump?
I agree with the thoughts on the turbo. The is38 keeps up very close to stock on the bottom then beats it till red line. This would even work for the auto. The auto shifts at 6700. Not theoretically perfect. But very close and more than good enough.
Given the same pressure and same duty cycle, don't larger injectors flow more?
Rough example with made up numbers:
"X" duty cycle and "X" pressure with TSI injectors = 7
"X" duty cycle and "X" pressure with GTI injectors= 10
If so, then the only question is, can the ECU pull back the duty cycle enough to be okay at low load? Then at high load you get more flow available from the larger injector?
Wrong?
TwinDad
Autocross Newbie
- Location
- Fort Lee, NJ
Somehow BMS was able to plug and play golf R injectors on the gti with an IS38. I have a feeling the 1.8 would behave the same way. APR used to sell just injectors as part of the stage 1+ on the old 1.8. I'm pretty sure the computer can read what the engine is seeing and adjust the fuel pressure that is given to the injectors. I would suspect that this is a better solution than a fuel pump that is just increasing the pressure on the stock injectors to make up for the lack of fueling
TwinDad
Autocross Newbie
- Location
- Fort Lee, NJ
Wouldn't just swapping the pump for one from a gti solve the issue? And if ECU doesn't know that you swapped the injectors, it will still read what is going on and adjust the flow going to them and the rates to achieve the proper AFR
Arin@APR
GOLFMK7 Official Sponsor
- Location
- Auburn, Al
- Car(s)
- B8 S4, MK7 GSW TDI
They aren't on a duty cycle. It's 100% open for a calculated amount of time.
The ECU knows several things, mesures some, and calculates others. It knows what the injector size is, so to speak, and how much fuel should be delivered at various rail pressures, then interpolates between each known value. It thinks it knows how much fuel the HPFP can deliver, assuming the LPFP is delivering the correct amount of fuel (which it actually doesn't know). Assuming the amount of fuel delivered to the HPFP is correct, and assuming the injectors are working properly, it thinks it knows when to fire the HPFP solenoid open and closed to deliver fuel to the rail based in part on the size of the HPFP piston diameter and stroke. It checks the rail pressure with a sensor, and if it's off, it trims the amount of time the HPFP solenoid opens and closes to help deliver the correct amount of fuel, but it's limited and not really designed for adding a much larger HPFP. The injectors then open for a set amount of time based on pressure in the rail. This is also based on what the ECU thinks it needs to deliver to achieve the prescribed air fuel ratio assuming everything is up to snuff, and the fuel quality is spot on (it never is). The o2 sensor then checks to see if the correct amount of air and fuel were delivered. If something's off, either fueling from ethanol content, fueling from a component out of spec, or airflow higher or lower because a sensor is off, or there's a leak somewhere, a trim is added. The trim will go + or -, which basically lets the ECU know it needs to deliver a little more or less fuel. However, this window is also limited. It's not designed to handle upgrading the injectors.
The proper way to change the injectors is to tell the ECU the characteristics of the new injectors through new ECU mapping.
Check above for more details. Also, the HPFP on the Golf and GTI are made by different companies (Bosch / Hitachi). They don't fit w/o an adapter and some work. However, the solenoid is controlled differently. So, they are 100% not compatible. The ECU will not send the correct messages to the HPFP, so it simply will not work.
MeltedSolid
Autocross Newbie
- Location
- San Francisco Bay Area
- Car(s)
- '15 Golf, e36 328i
That's extremely useful Arin. I've always been wondering what exactly the trims mean and this completely clarified it for me. Thanks for getting into the nitty gritty.
4MotionWagen
Ready to race!
- Location
- Michigan
Do it after install the new turbo will work fine with the stock map.
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Arin@APR
GOLFMK7 Official Sponsor
- Location
- Auburn, Al
- Car(s)
- B8 S4, MK7 GSW TDI
The Golf R intercooler is marginally better. For the amount of time / labor involved, get something good.