Subaru Forester Owners Forum banner

18G Upgrade, Suggestions?

59234 Views 495 Replies 32 Participants Last post by  Rescuer
Hey everyone, so I am planning to upgrade my turbo to a TD05-18G 8cm from Kinugawa. Currently I have a Cobb DP and Invidia Q300 CBE and was hoping for some suggestions or feedback on my plans for my power modifications.

I plan on going with:
DW65 fuel pump
ID1000 injectors
Cobb SF intake with heatbox (maybe, depends on my ability to grab one from a buddy of mine)
And of course a good pro-tune

Any suggestions, feedback, what would you do differently? Thanks!
1 - 20 of 496 Posts
td05, Td06sl2 and H 20g are 47lb per min td05 18g is 43lb per min. The td05 will spool faster but fall of quicker up top being a smaller turbine housing and wheel and will make less power because of this. Just based on boost alone my td04 would taper to 9 psi, my vf52 would taper to 16psi and my td06sl2 20g 8cm will taper to around 20-22 psi. Even my friends 2.5xtr tapers to around 22-24 psi at redline and its a 49lb turbo. The only turbo that will not taper on our 2.5 liters would be 35r territory in the 55lb and up size. My 20g will hit peak 26psi at 4200rpm and when it shifts at 6300rpm it will have tapered to 20-22 psi depending on the gear but believe you cant even feel it taper as it pulls hard to redline. The larger the housing/wheel the more power it will make but will also shorten the power band by spooling later. The td06 will alway make more power then a td05 but it all depends on what you want the turbo for? I drag my car and rarely beat on it around town and find the td06sl2 to be perfect for that. When i am at the track there is never any lag because i am launching in boost and after it launches the rpm is never below 4200 rpm so it is never out of peak boost.
Here is a good comparison of different turbos
See less See more
The flow ratings are the same but not on a compressor map. They both will flow 47lb but the td06 will flow that max for a longer period of time its just the way it is. At the drag strip our cars should be pretty close to the same but i would think the larger turbo would have more power were its needed but the better spool of yours would help the 60' time. That is why i am getting the high stall converter to help me spool at launch. But once you launch as i said your rpm is never low enough to make spool time a factor since you will always be in peak boost from there on out. Long story short it would be very close since your better launch would make up for my top end. Even with not being able to build boost on launch i still have managed 1.9 60' times but my vf52 i would be around 1.7. I hope with the ipt converter i can get the 60' back in the 1.7-1.6 area putting me in the mid to low 11's.
After my car is back and running we should compaire some logs and see what the diffences really are for other people to get a idea. Also the td06sl2 is smaller then a td06h also if you look at the mhi turbos in the turbo faq i put up it should say all of it. Also I used to be able to hold boost alot longer until i put on my equal length header. The more your engine flows the more the turbo chokes up top.

Yes lets pic this back up in my journal!!
The difference between the 20g and 18g will be pretty unseen on pump gas. You will really like the 18g it will be more then enough power for a dd and will be just as fast as a stage 2 sti if not faster.

Sent from Free App
I wouldnt say unseen. Its not like the switch from td04 to something else but its noticeable for sure. Its probably gotten me close to where I was on e85 on the 18g. Probably a bit shy. Maybe 30-40 more hp than gasoline and 18g combo.
I didnt mean to say that the 20g wont make more power. Just that unless he is maxxing things out like you and me the td05 18g can make close to the same power as the td05 20g on a nice dd tune. But if you are looking to break things like us then the 20g is more your style lol.
Gotta pay to play without the correct tune anything above 300 whp is a death wish lol.
You need to delete your tgv and remove your intake manifold for a 3'' inlet so you want 2.4

Sent from Free App
I would do the 8cm and port it and make sure you do the 08+ wrx fitment

Sent from Free App
I would ask ray about the other stuff his prices may be better then there Black Friday sale. The cnt top mount is the same as the fms and is the process west knockoff

Sent from Free App
No twin scroll as you will need a different header and downpipe but I would do the billet wheel if you got the extra money.

Sent from Free App
I would get the journal bearing Gtx2863r over the kinugawa as it has the nicer 9 blade turbine and gtx compressor.

Sent from Free App
No he is offering you the turbo i mentioned the gtx2863r which is a 18g with a billet compressor and 9 blade turbine that retails for $825 but will give it to you for the black friday $800 price. The ball bearing turbos are on sale for 1200 which is also a good deal but i feel the gtx2863 is the better deal hands down and will be more then enough on a 91 oct pump gas tune.
Don't worry about the r you want to port it and 8cm and done.

Sent from Free App
It's confusing but Ryan summed it pretty well for you. It ultimately your choose but if it was me I would get the one I mentioned.

Sent from Free App
First off the spt will be fine my megan racing catback is 2.5'' and i dont see it as a restriction at all yet. Second off the most of the tmic for our car is going to be legacy style fitment except the process west and its knock offs (fms and cnt) but you will need to purchase a seperate hose to run the sti turbo as it does not come with it. Also the sti style flange turbos do not line up correctly with out spacers on the uppipe which the legacy style turbo comes with.

Also with the fms tmic you will have to tweak a couple things from what ryan says the splitter does not line up and different size bolts for the bypass valve neither are a big deal but good to know.
No get any tmic you want but I prefer a legacy style turbo as I have seen fitment issues with sti style units.

Sent from Free App
No matter what turbo you buy you will need this.Turbo Inlet Flange SUBARU EJ20 EJ25 WRX STI Manifold Flange / Turbine Inlet Mild steel

The legacy style turbo comes with it and i run it on my car or the inlet will not line up. If you buy a sti style turbo you will need to buy this seperatly as it does not come with it because its not needed on sti style fitment cars.
No the process west and fms will allow you to run a sti style turbo but you need to buy a adapter hose as it does not come set up to run the sti turbo. The perrin , avo and spearco are legacy style only. If you want to run a sti turbo you need the flange above for a spacer and you also need this Process West Traditional Turbo Adapter Hose for 08-13 WRX TMIC to go along with your process west or fms tmic.
1 - 20 of 496 Posts