FP Big T28 VS T25

[VPrime]

Just wondering if the big t28 would be a "noticeable" upgrade if I kept boost at 10Psi or so?
This would be ona generally stock car (no fuel mods yet, walbro pump planned).

Current mods:
2.5" UICP
hard inatake pipe
1stgen BOV(crushed)
3"Cat back (not on the car)
3" Straight through down pipe (not on the car)
Boost (on t25) set at 15 PSI

So If I throw the big t28 on and set boost at roughly 10psi would my car feel slower, or quicker then what it is now at 15psi?

Also What would be the max boost safe to run with my current mods, I know I should get a logger to see (have one but cant get it working) But just looking for some thing very rough to go by for now.

Thanks.

 

[PieEyedPiper]

I believe that you will not notice much increase in power. But I do know what you will percieve:

-slower spool time (negligable, as the Big T28 hits max boost at around 3000rpm)
-better top end because the greater flow produced can keep up with the engine at high rpms
-improved consitancy because of more efficient wheel designs that will produce less heat

With your mods I would say you're capable of maybe 13-14psi safely. But as you are already aware, theres only one way to find out.

 

[wret]

At lower boost levels the T28 will actually seem slower than the super quick spooling T25. You will not notice much difference in the high end until you get up to 15psi or higher.

If you really want to turn up the boost, make your next mod a logger.

 

[Eastwood95]

Start by getting the exhaust you already have.......INSTALLED..........and get your logger working. The exhaust alone will give you a very noticeable gain in power...even on the T-25

This debate has been discussed over and over but why would you want to go with the T-28 over a MHI (14b, 16g) turbo set-up?

 

[daren_p]

Rewire your fuel pump if you haven't already & you should be able to run around 13 psi with the T28 & it be safe. I don't have first hand experience with the T28 but I do with the evoIII & they are similar in power output with the evoIII having a slight advantage. I would think even at 10 psi vs the 15 psi on the 25 it will still feel atleast as fast since it wont fall flat on its face by abit over 5000 rpms. I know my evoIII at 13-14 psi felt like a completely different car compared to the T25 at 16 psi, even at lower boost it made a big difference.

 

[Rice Over Wheat]

This debate has been discussed over and over but why would you want to go with the T-28 over a MHI (14b, 16g) turbo set-up?

Because it's straight bolt on with stock smic, zero modification, and equal to a B16G in power. The only turbo upgrade that is true bolt on. Some people don't have plans to get a fmic or upgrade much beyond mild mods. If he was going to go through the trouble of 16g he might as well go evo3.

As for spool diff it's negligible between T25 and T28. The AGP BT28 I used to have fully spooled by 2800 rpm. And it's a big difference over a T25 especially if you get the FP 17psi actuator upgrade.

 

[endeffect0]

if you install the turbo back exhaust, maybe a intake and o2 housing. You should notice a good difference even at lower boost, the whole system will flow a lot better, might even spool as fast as you t25 with the stock exhaust and intake? You should notice an increase in top end because the t25 trails off at five. definitely do the fuel pump rewire mod too, that will help if you want to turn up the boost.
Just out of curiosity why are you planning on running lower boost on a better turbo?

 

[wret]

As for spool diff it's negligible between T25 and T28. The AGP BT28 I used to have fully spooled by 2800 rpm. And it's a big difference over a T25 especially if you get the FP 17psi actuator upgrade.

Many T25's (including mine) are able to fully spool in 2nd gear at 2500 rpm or below. Actually, with my setup it was closer to 2400. And 2800 on a T28? That's hard to believe. Most hit full boost at 3000.

Regardless, there's a difference in spool of somewhere between 300 to 600 rpms. For me this was very noticeable and not what I would call negligible. When you are too low in 2nd gear and nail the throttle on an autox course, that wait time for full power can seem like an eternity. This could seriously affect strategy.

 

[Rice Over Wheat]

Maybe on autox, but for dd 300 rpm is nothing and he gets the payoff in a better power band. I don't think he said anything about racing unless it was in another thread. Most people here seem to have FP BT28s. I had an AGP BT28. From what I've gathered over the last few years, it appears people running FP BT28s tend to dyno more power than I was ever able to squeeze out of my AGP BT28. I'm not sure what the exact differences are between their exact specs, but it's not a far stretch for me to believe that the AGP turbo may spool faster than the FP but have less potential for max power. I definately spooled 2800, quite close to stock.

In fact, I have a Bullseye 50 trim with the borg-warner core right now and see full spool at 3700, pretty much in between a journal or bb garrett. Spool starts at 3000. Lots of subtle differences in design can make for different characteristics. T28s can vary by all kinds of different trims/wheel choices.

 

[VPrime]

Thanks for the replies guys.. The exhaust will be on, and data logger will be working BEFORE I put the turbo on.
Also, Why im getting the t28? Because a deal came up and I can basically pick it up for the price of a 14B+install kit... so cant go wrong with it there
I may also have some money for a fuelpump by the time i put it on

 

[daren_p]

Its been a long time since I was completely stock but if I recall correctly spool up was around 2800. When I added ic pipes, turbo back exhaust & porting it dropped to just over 2400. I think with him going from a stock exhaust setup to an aftermarket will help making the spool time between the T25 & T28 very similar, plus you gain a turbo that doesn't fall flat on its face at 5000 rpms.

If your planning on keeping the boost low, just for the fact you don't have the supporting fuel mods, you can get away with abit more then 10 psi. 13-14 psi should be safe & yes you will defently notice a difference between the T25 & T28 at these levels. If you get that logger of your up & running you may be able to get away with 15-16 psi but you will be maxing the injectors out (& these levels are with a FP rewire)

 

[95blackGsTurbo]

You are right Daren. I was hitting full spool with my FMIC, 3" turboback and intake around 2400. I upgraded to a Big T28 Super 60 and I hit 22psi daily around 3100rpm. Turbo is awesome. With a set of 550's, 190lph and an AFPR it was very easy to tune. Car put down over 320whp and that is a good amount for me being FWD. Very streetable turbo as well. I have had 50 trims, 60-1 and whatnot and I love the quick power I can get going through AZ traffic. The wastegate should be at 11-12psi stock. You can get a new actuator but MBC is good enough. I say get a logger and maybe thing about getting a 2.5" exhaust or an o2 dump and porting the turbine housing. With a full 3" I was getting some pretty bad spike, set at 18 would spike to 23. Put on an o2 dump and ported the turbine housing and now I can hold 22psi all day long on pump with 0 knock.

 

[Dan97gst]

I just installed the T28 my self with all the fuel mods and exhaust, mine doesn't hit ful boost until alot higher in the rpm rang like 3,7k or 3,8k on 19lbs. Why is it that alot of yall are hitting full boost quicker? Could it just be my boost gauge is off or what?

 

[Rice Over Wheat]

exhaust leak / boost leak

 

[daren_p]

I just installed the T28 my self with all the fuel mods and exhaust, mine doesn't hit ful boost until alot higher in the rpm rang like 3,7k or 3,8k on 19lbs. Why is it that alot of yall are hitting full boost quicker? Could it just be my boost gauge is off or what?

Something is defently up with your setup, those spool times are way to high for that size of a turbo & looks like your still running stock cams (spool faster vs aftermarket). First things are check for intake & exhaust leaks. Next check the wastegate actuator, if its adjustable if may not have enough tension & is blowing open to early. Those would be the most common areas to start with.