GT25R in... Laggier than a MOFO

[240SXer]

Okay, everyone said it was bad, but I didn’t expect it to be this bad. It's decent to cruise around because it'll easily build 1-2 psi for driving around (actually better at low rpms than the T25 low being 1k-3k) but it takes till about 4100-4200 to hit full boost. It's not horrible but it takes getting used to. It's only like 200-300rpm higher than the T25. But it's actually easier to drive around town and on the freeway, I assume because it's a ball bearing. It's a GT25/40R .86 A/R with a Tial 38mm wastegate and a .4 bar spring. (it's only running 4.6 psi because I’m at 2800ft) It's pretty quick for such low boost though. I walked a S13 w/SR on stock boost. And a couple mustang GTs on Saturday night.

It's pretty hard to launch with my Nitto DRs, I have to rev it so damn high. I think it'll be a lot better as soon as I’m running some decent boost. But I have to dump it at about 5.5-6k to get it to stay into boost after the tires hook, any lower it'll bog to like 3k then I’ll sit there while people smoke away from me.

The lag isn’t as bad as I’m making it sound, but I’m just not used to it. The boost comes on smooth too, not at a solid kick like the T25 did. I'm overall pretty happy with it. But it's hard to say till I ge the turbo up to where it was made to be.

I'll post some pix tonight. When I get home....

[f150intally]

thats about right. you will see 20psi by 4600-4800 right?

[msaskin]

Not sure what your plans are, but some cams should really open up the low end. Either way it's good to hear some semi-solid numbers from someone with this turbo.

I'm planning on probably 256 (or 264...don't really know) cams and a .64 a/r GT25, so we'll see.

~matt

[240SXer]

Ya, i'm thinking i'm going to go with 264/264 step 1 cams. I'm going to get that and a 1.2 head gasket and maybe a valve job and valve springs. That's later though, for now i've just gotta get my injectors and get my ecu tuned.

[Gladius]

If anything, cams will make the bottom end worse.

[Gladius]

Yes the gt25r feels laggy compared to a t25. I know mine does. At the track, I had to drop the clutch at about 6k to see any decent times.

[gani]

thats pretty low boost you are running there. those turbos wake up pretty good with at least 15psi on them.

[VitaminT]

240SXer do you have your injectors, MAF and ecu in yet? I am betting that you will like it a lot more when you lay on about 17-20psi.

[RobDET]

Yah even the T25 spools faster at 14PSI then it does at 7. The wasgate is more closed longer. When you Crank up the boost it'll keep the gate totally closed till like 12 psi. Right now it is probibly starting to open around 3 or 4 psi.

[240SXer]

Ya, I hope it'll be a lot better. I probably going to get the injectors and ECU (already got the MAF) in about a month. Never enough money

[VitaminT]

Cool. Can you post pics of your Tial mounted to the manifold? I am interested in what it looks like and if you don't mind about how much it cost to have it done.

[msaskin]

Cool. Can you post pics of your Tial mounted to the manifold? I am interested in what it looks like and if you don't mind about how much it cost to have it done.

Ditto. I was thinking about running an external gate and trying to come up with a good way to mount it to the stock manifold. Ideally i'd love to mount it to my ssautochrome manifold, but I just don't see a way to.

Are you running the wastegate exhaust dump open, or is it recirculated back to the downpipe?

~matt

[240SXer]

Yeah, my friend had my camera and I didnt get it back till last night, it was too dark to take pictures. I'll try to take some today and post them tonight. If I don't get time to when it's light i'll just do it in the dark. Sorry about the lack of pix

Right now the wastegate dump is open, i'm not sure if I want it going back to the downpipe yet. Or if I want to get it's own seperate muffler.

[msaskin]

Yeah, my friend had my camera and I didnt get it back till last night, it was too dark to take pictures. I'll try to take some today and post them tonight. If I don't get time to when it's light i'll just do it in the dark. Sorry about the lack of pix

Right now the wastegate dump is open, i'm not sure if I want it going back to the downpipe yet. Or if I want to get it's own seperate muffler.

Makes sense. What I was thinking of doing with an external gate is flanging the wastegate dump at the end of the pipe, and doing a flange (and plate) setup on my downpipe (or just using an electronic cutout ), that way I can switch between open dump and recirculated at the push of a button (or at the removal/install of a section of piping)

~matt

[240SXer]

Ya, I was thinking about an electronic cutout too... Where can I find one?

It costed me 1900 total installed. Which isnt bad consitering the work that has to be done. Wastegate mounted on Stock manifold, stock wastegate welded, piping modified, etc. The wastegate costs like 250, and the turbo is like 1100, so 600 for install.

[msaskin]

Ya, I was thinking about an electronic cutout too... Where can I find one?

so 600 for install.

Try searching for the McCord power plate.

Also, $600...ouch...that's why I do all my own work

~matt

[240SXer]

Ya, I can't weld and stuff so there isnt really much I could have done myself. Plus, with the time it would have taken me i'm saving money by paying to have it done

[Gladius]

240sxer, does your wastegate mounting look anything like mine?

[msaskin]

Got pics from any other angles gladius? Perhaps something showing the dump pipe?

~matt

[240SXer]

Mine looks similar, but it's back a bit more. I'll take some pix tonight. I'm going to the track. How much boost do you think I can run with a .86 on stock fuel?

[robbbby]

Thisis what I did for my GT25R for external gate. I drilled a hole in my stock manifold, grinded a piece of pipe to fit it and welded the internal gate shut. It cost me $20 Canadian to have the welding done. I don't plan to pipe the wastegate back into my downpipe. I also made my own wastegate flange with numerous holes that way I have like 30 degrees to play with wherever I want to point it

Here is the pictures, they are really big sorry.

http://home.cogeco.ca/~rnotara...1.jpgh ... ra...2.jpg

[Gladius]

Got pics from any other angles gladius? Perhaps something showing the dump pipe?

~matt

Dump tube? What dump tube? LOL. Can you say loud?

I'll need to take some pics from other angles.

[Gladius]

Mine looks similar, but it's back a bit more. I'll take some pix tonight. I'm going to the track. How much boost do you think I can run with a .86 on stock fuel?

.86?Are you reffering to your A/R? Stock fuel? You mean 93 octane?

If so, with proper fuel upgrades i.e. fuel pump, bigger injectors, ecm programming... 17psi on pump gas. With stock fuel system, 8 psi max will keep you safe. Thats about 240-250 whp, which is the max of the injectors.

[msaskin]

Dump tube? What dump tube? LOL. Can you say loud?

I'll need to take some pics from other angles.

Cool.

I'm just going off the assumption you don't have the wastegate gases dumping onto the brake master cylinder, but then again, I've seen stranger.

~matt

[Gladius]

Cool.

I'm just going off the assumption you don't have the wastegate gases dumping onto the brake master cylinder, but then again, I've seen stranger.

~matt

More along the firewall inbetween the motor and brakebooster.

[msaskin]

Ok. I'm beginning to get ideas. Maybe I'll just get the gate and have it put on my stock manifold, and then swap the stocker/external gate setup in and trash/sell the ssautochrome manifold.

I can't figure out any way to mount an external gate off the autochrome manifold, aside from maybe doing a pipe/flange sticking off the #4 runner or something.

~matt

[VitaminT]

It is late and I am probly thinking crazy again, but could you not make a spacer place between the mani and turbo that had the tube/flange for the gate welded to it.

Hehe, yeah yeah I know, it will cause major clearance problems with the engine mount bracket.

[240SXer]

Here are the pix:

http://www.nissaninfiniticlub....73290

[msaskin]

Hehe, yeah yeah I know, it will cause major clearance problems with the engine mount bracket.

Hell, a GT25R has engine mount clearance problems to begin with

Maybe with a custom manifold to raise the turbo up some, but then you may as well just make a WG flange on said custom manifold

~matt