Very poor spool on 18G
05 November 2018, 12:04 PM
#1
Very poor spool on 18G
Hi,
rescently had a TD05 18G fitted along with a bunch of other upgrades. Compared with the VF23 i had fitted before the turbo lag is pretty awefull. There is no mid range swell of torque to speak of and it generally feels pretty flat much bellow 5000rpm.
The engine is a fully forged 2.1 with 270 Cossworth cams and upgraded valves and springs. It's mapped speed-density on Simteck engine management. Injectors or 740cc, exhasut headers and up-pipe have all been replaced along with new gaskets. The boost control solenoid has also been replaced. My garage said they had ot at the mappers 3 times to try and get descent (expected) figures out of it...
The 18G was purchased as a used part... Engine runs great otherwise.
I'm thinking i try a different 18G to trouble shoot for a duff turbo... any other ideas? I'll ask the mapper if he saw anything during mapping that could suggest compression/head issues.
Thanks in advance!
rescently had a TD05 18G fitted along with a bunch of other upgrades. Compared with the VF23 i had fitted before the turbo lag is pretty awefull. There is no mid range swell of torque to speak of and it generally feels pretty flat much bellow 5000rpm.
The engine is a fully forged 2.1 with 270 Cossworth cams and upgraded valves and springs. It's mapped speed-density on Simteck engine management. Injectors or 740cc, exhasut headers and up-pipe have all been replaced along with new gaskets. The boost control solenoid has also been replaced. My garage said they had ot at the mappers 3 times to try and get descent (expected) figures out of it...
The 18G was purchased as a used part... Engine runs great otherwise.
I'm thinking i try a different 18G to trouble shoot for a duff turbo... any other ideas? I'll ask the mapper if he saw anything during mapping that could suggest compression/head issues.
Thanks in advance!
05 November 2018, 01:14 PM
#3
engine is V5/6. Garage found the up-pipe to be restrictive at high rpm and replaced with a faster flowing item. Exhaust headers had given up and were replaced like for like as far as i am aware. The garage are subaru specialists, no parts were fitted that under any normal circumstances should restrict a pretty humble 18G in their experience.
It's an interesting one....
It's an interesting one....
05 November 2018, 01:34 PM
#4
Do you have any rpm vs. boost plots?
As Alyn has eluded to its most likely the pipework before or after the turbo causing issues. What are you running after the turbo? I've heard of cats letting go and causing issues.
Standard subaru headers would be absolutely fine for the power an 18G can put out. A little porting here and on the uppipe will certainly improve gas velocity and ultimately spool up times.
What exact headers and uppipe do you have fitted?
As Alyn has eluded to its most likely the pipework before or after the turbo causing issues. What are you running after the turbo? I've heard of cats letting go and causing issues.
Standard subaru headers would be absolutely fine for the power an 18G can put out. A little porting here and on the uppipe will certainly improve gas velocity and ultimately spool up times.
What exact headers and uppipe do you have fitted?
05 November 2018, 02:42 PM
#5
The headers will be standard subaru, don't know what exact up-pipe was fitted, though like i said it improved the top end. We are not really talking about trying to recover a couple of hundred rpm of spool, it is very pronounced and you never get anything like the swell or torque seen on the previous VF23, even 2500rpm further up the rev range. No mid range at all really.
The car runs a sports cat which did pass emmissions for the MOT prior to the modifications (car stayed at garage was not used in the interim). A worthy concideration, none-the-less.
I'll see if the mapper has any graphs from the dyno tuning, some objective data would be very helpful!
Cheers
The car runs a sports cat which did pass emmissions for the MOT prior to the modifications (car stayed at garage was not used in the interim). A worthy concideration, none-the-less.
I'll see if the mapper has any graphs from the dyno tuning, some objective data would be very helpful!
Cheers
05 November 2018, 03:33 PM
#6
Id be looking at the up pipe if everything else has been diagnosed as working fine, think of blowing a candle out with a straw from a wd40 can compared to a straw from a mcdonalds drink, thats the effect it will have on the spool/spinning those vanes
i bought a 2nd hand up pipe from ebay before i bought the trick up pipe, i think it measured something like 80mm in diamter ( way to large for my liking) compared to around 63 of the trick up pipe/ standard up pipe diamters.
i bought a 2nd hand up pipe from ebay before i bought the trick up pipe, i think it measured something like 80mm in diamter ( way to large for my liking) compared to around 63 of the trick up pipe/ standard up pipe diamters.
05 November 2018, 04:29 PM
#7
I agree, I'd be looking at the up-pipe to start with. Bigger isn't always better.
Ring Alyn @ AS Performance and talk to him about your headers but primarily the up-pipe and look to get a Harvey up-pipe that suits your setup. They are designed to speed up the gas going into the turbo to aid spool.
Your "specialist" should have known this.
Ring Alyn @ AS Performance and talk to him about your headers but primarily the up-pipe and look to get a Harvey up-pipe that suits your setup. They are designed to speed up the gas going into the turbo to aid spool.
Your "specialist" should have known this.
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05 November 2018, 04:45 PM
#8
I think my specialist does know this. The standard up-pipe was on for the first mapping session where lag and poor spool were observed. A faster flowing up-pipe was then fitted to see if it remedied the lag and although it improved things in the higher rpm range it had no effect on reducing lag or improving spool. An 18G should (and do!) perform far better mid range without having to look at fancy pre-turbo exhause solutions
05 November 2018, 06:39 PM
#9
if there are no leaks, and they'd be obvious tbh to delay spool to 5k RPM (my 20g spooled at about 4k when the bolt i pluged the heat sensor hole with fell out), then I'd look to the turbo personally (especially if it was poor with the standard up-pipe already).
Has the actual exhaust been checked? downwards from turbo, i mean.
Has the actual exhaust been checked? downwards from turbo, i mean.
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