Loss of low end torque: FP T-28/FP manifold +3" exhaust

[travs_dsm]

So I'm building out my 1997 GSX Auto for a mild build with a 300WHP goal as a start. I'm wondering if I went overboard starting out. Here is what I have thus far:

New Forced Performance T-28 Turbo
Forced Performance Racing Exhaust Manifold
Forge Recirculated BOV
3" inlet Downpipe
3" Thermal Cat back exhaust
3" High Flow Catalytic Convertor
Walbro 255
Fuellab AFPR
Innovate LC-1 Wideband (not really doing anything right now, but installed)
Running Stock Boost until injectors and tuning are done

(I have some 780CC Injectors, DSM Link V3 and other stuff as well, but not installed yet)

The problem I have right now is that I lost power before going into boost. It makes driving it no fun due to all of the lag. I'm wondering if I'd be better off with the stock Exhaust Manifold or changing out the downpipe to a 2.5" version?

I have verified there are no exhaust leaks or boost leaks at least up to 20psi, so I'm at a loss.

Everything I read about turbos stated that less backpressure would make more power and the car definitely feels punchier once it goes into boost, but it is a real slug right now off the line. Should I wait until the build is complete before giving up on the FP racing manifold? Is the T-28 too small for it? Any advice would be appreciated! Thank you.

 

[JusMX141]

Larger turbo = trading low-end response for more airflow. It's the name of the game, unfortunately.

If you think a T28 is laggy...wonder how a GT35R would feel?

 

[donniekak]

What rpm do you see full boost?

 

[travs_dsm]

I'd say around 3000 rpm? I'll need to go check to be sure.

 

[dexterholland04]

Try making full boost at 5100 rpm on a big turbo...3000 rpm is nothing! I would double check to see if you have any pre-turbo exhaust leaks; but 3000 rpm sounds just about right for a Big T-28.

 

[travs_dsm]

Haha, man that would be crazy! I guess I shouldn't be complaining eh?

 

[pboglio]

1) Compared to a T25, a T28 is laggy.
2) The FP race exhaust manifold is more for high rpm kick.
3) The FP race exhaust manifold should be properly heat shielded, or just reuse your stock heat shield. All the heat loss and underhood heat will hurt low/midrange and just make the car feel gutless, ask me how I know this.
4) Install DSMLink with the injectors, add some ignition timing, pull some fuel, dial in the injector deadtime. My car likes 390 microsec deadtime, right up to the point where the 02 sensor barely cycles. This helps the throttle response tremendously, anything near the suggested 180 microsec deadtime and throttle response is lethargic, YMMV.
5) I like a 2.5" downpipe, 3" not so much.
6) I don't like cats, but it shouldn't affect low end response and in fact tends to help the very bottom end at the expense of some slight turbo response and a bit of high rpm power.

 

[Kalub]

3) The FP race exhaust manifold should be properly heat shielded, or just reuse your stock heat shield. All the heat loss and underhood heat will hurt low/midrange and just make the car feel gutless, ask me how I know this.

I'll bite. How?

 

[travs_dsm]

1) Compared to a T25, a T28 is laggy.
2) The FP race exhaust manifold is more for high rpm kick.
3) The FP race exhaust manifold should be properly heat shielded, or just reuse your stock heat shield. All the heat loss and underhood heat will hurt low/midrange and just make the car feel gutless, ask me how I know this.
4) Install DSMLink with the injectors, add some ignition timing, pull some fuel, dial in the injector deadtime. My car likes 390 microsec deadtime, right up to the point where the 02 sensor barely cycles. This helps the throttle response tremendously, anything near the suggested 180 microsec deadtime and throttle response is lethargic, YMMV.
5) I like a 2.5" downpipe, 3" not so much.
6) I don't like cats, but it shouldn't affect low end response and in fact tends to help the very bottom end at the expense of some slight turbo response and a bit of high rpm power.

I think you are definitely onto something about the heat. I went and stuck the stock upper heat shield on the FP manifold the best I could and it DID make a noticeable difference! I already had the lower heat shield on so I'm good there. There still seems to be a lot of heat escaping out of the huge gap created by FP manifold with the stock heat shield wedged on top of it. Apparently no one makes a heat shield for it either.

I will say this about the T28, even at stock boost it is a noticeable difference in power once it spools. I'd almost equate it to a wall of torque kicking in and it seems like it would go all the way to redline, but I'm not going there until the bigger injectors are in and I'm tuned. I'm almost afraid to crank it up once the rest of the supporting mods are in!

 

[pats16valve]

How do you reattach the stock heat shield to the FP manifold?

 

[travs_dsm]

How do you reattach the stock heat shield to the FP manifold?

Well I just kind of wedged it on top of it. The right side of the heat shield kind of wraps around the side of the FP manifold to hold it on. It is ghetto as heck, but it is better than nothing. I'm thinking some metal straps may help to hold it better. I need to come up with a better solution though...

 

[liquidsilver]

Well I just kind of wedged it on top of it. The right side of the heat shield kind of wraps around the side of the FP manifold to hold it on. It is ghetto as heck, but it is better than nothing. I'm thinking some metal straps may help to hold it better. I need to come up with a better solution though...

There is also this place - Imports

Here is an old thread on it - http://www.dsmtuners.com/forums/custom-fabrication/366717-fp-manifold-heat-shield.html#post152284061

I'm considering this route but I may just try to modify the stock heat shield and see how it goes

 

[pats16valve]

Gotcha, that makes scents. I knew there wasn't a way to put it on there directly.

 

[Oldsid]

There is a very simple way to make a decent heat shield for an FP manifold for almost nothing but a little time and patience. This method works on stock turbo or 16G but I think it may be adapted to other turbo's.
Take the stock heat shield of a non turbo DSM and shape it around the edges of the FP manifold. Once it looks right to you, drill a hole on the heat shield to match the bottom stock heat shield and then just bolt it to the turbo. The stock heat shield can be found in any junkyard for a couple of bucks.
Here is a picture of mine on the FP manifold.

 

[nickk90]

Do you have to WG actuator that came with the turbo or the adjustable version? Do you have a boost controller installed?

On my car with out the boost controller hooked up on the actuator that came with the turbo my car felt laggy. I bet the adjustable actuator would fix that problem. But with a boost controller installed and backed off to 14-15 psi its not laggy at all

 

[Pipnorcali]

It should be slamming you back in your seat around 3500

 

[GDNF2ET]

Get a test pipe to replace that cat and post back...

 

[97gsxIA]

Get DSMlink installed, I was worried about lag too until I got my launch perfected (Well I don't know about perfect... but I like to think so ) You shouldn't be worried about getting off the line with AWD and link.

Nostalgia: That first moment when you launched so hard your windshield whipers flipped on.

 

[gprix1]

New Forced Performance T-28 Turbo - Good choice for 300hp. Fastest spooling turbo you'll find for that hp goal.
Forced Performance Racing Exhaust Manifold - Not needed. Stock 2g manifolds have pleny of flow for 300hp+. The bigger manifold will give you nothing on top-end with a T-28 and the larger runners will only serve to slow your spool time with their lower velocity.
Forge Recirculated BOV - Stock 1g BOV would have been my recommendation here for your setup. cheap, no adjusting, and oem reliability
3" inlet Downpipe - Good choice
3" Thermal Cat back exhaust - Also good
3" High Flow Catalytic Convertor - Adds a bit of restriction but with 3" everywhere else it may actually help keep boost spikes in check - I would also get a test pipe and see how you like it.
Walbro 255 - With a T-28, a rewired 190 is plenty of fuel, quiet, and doesn't require an ajustable AFPR
Fuellab AFPR - Not needed with a Walbro 190
Innovate LC-1 Wideband - Definately want this. This and a boost gauge are pretty much mandatory once you start upgrading.

Your setup would be more suitable for something like an FP68HTA or 20G in fact it is almost exactly the same as my 20G GSX. My girfriends 95 GSX however is being build with an FP Big T-28 and the parts I recommended for you are how I've done T-28's in the past and how we're setting her car up now. With my previous T-28 setups the spool was almost instant and made for a great street and Auto-X setup. Our goal with her car is to have it be a simple, reliable, and fast daily driver. I would also suggest some 264 cams but that would honestly be the 'last' thing I would spend my money on.

 

[Archer Fabrications]

Get DSMlink installed, I was worried about lag too until I got my launch perfected (Well I don't know about perfect... but I like to think so ) You shouldn't be worried about getting off the line with AWD and link.

Nostalgia: That first moment when you launched so hard your windshield whipers flipped on.

Hahah wow that happened to me on a 3rd gear pull on the highway, not quite on a launch though haha still haven't replaced it!

If you think a t-28 is laggy try a 57 trim

 

[gofer]

As far as a heatshield goes, there is an aftermarket blanket that a company manufacturers for the FP manifold and costs just over $100. Here are a few shots, these were pulled from a thread on ECMLink forums and if you'd like the contact info for it PM me.

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After 3k miles...

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Seems like it works!

 

[91-gsx]

You can get the stock heat shield to work well with the FP manifold. Also, here are a few pictures of a stock 1G intake that was made to work with a 2G MAS. It was also converted into a cold air intake by turning the intake air box. I capped it off with a 3" BLOX velocity stack. You can take the top of the box off and change the filter, just like the factory unit. Here is everything painted and done.

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Tony

 

[travs_dsm]

Wow, just got home from work and there are all great responses in this thread! Thank you very much for the help!

I'd love to run with no Catalytic Converter, but they smog here in Northern Virginia and I will fail the visual inspection without one.

Yeah I'm thinking I probably went overboard with the FP Manifold, but since it on there now, I may leave it and check out that blanket gofer showed on here!

 

[GDNF2ET]

Get a test pipe made so it bolts up exactly the same as the cat...So you can easily switch them back and forth for inspections..This is not expensive and the 1st mod I would do...JMHO

 

[Pipnorcali]

Wow, just got home from work and there are all great responses in this thread! Thank you very much for the help!

I'd love to run with no Catalytic Converter, but they smog here in Northern Virginia and I will fail the visual inspection without one.

Yeah I'm thinking I probably went overboard with the FP Manifold, but since it on there now, I may leave it and check out that blanket gofer showed on here!

I run stock downpipe n cat and it ran 106mph in the 1/4 mile