Question about Greddy SP exhaust as part of BPU

883 Views 29 Replies 5 Participants Last post by Joose, Nov 29, 2001

supra_10

Discussion Starter · Nov 14, 2001

I’m contemplating a gradual BPU to achieve 400-420 HP at crank.
Considering Greddy SP, RMM DP, possibly a Hi Flow cat and a Profec B boost controller.
Will the Greddy SP let me reach this HP goal or do I need to go the PE route?

Any and all feedback would be appreciated.

Thx,

Jay :beer:

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WayneCar

· #2 · Nov 14, 2001

Not sure about the cat but I have the Greddy SP,
Bleeder,K+N, dp, and BCC and have gone [email protected]
I think the SP is a great choice if you want a quiet exhaust.
The car weighs 3640 with me in it. That trap would put
rear wheel hp at about 430 and crank around 500.
Wayne

supra_10

Discussion Starter · #3 · Nov 14, 2001

Thx Wayne.

R these HP figures verified?
I talked to several guys that deal with BPUs and they thought that 430 @ crank is barely achievable w/o going to a higher level.
I'm gladly surprised, again, IF these figures r verified on dyno.

Thx again,

Jay

WayneCar

· #4 · Nov 14, 2001

I have never dyno'd but those numbers are in
line with many BPU cars that have dyno'd. I think
I have a slightly stronger than average car based
on trap speeds but very close to average.
Wayne

supra_10

Discussion Starter · #5 · Nov 14, 2001

Thx, Wayne!

Jay

NowWhat?

· #6 · Nov 14, 2001

It also depends on your area, and the weather at the time.

Usually here in SoCal (where we both are), when we dyno, we actually get more HP via a correction factor that standardizes the #s so they are comparable regardless of where you're located. In the midwest and other colder areas with ideal conditions, when the correction factor is used, it usually takes away HP, rather than give it.

This doesn't mean anything on the track as they will still run a great time, but basically the correction says they wouldn't run the same in other areas, such as sunny SoCal...

supra_10

Discussion Starter · #7 · Nov 14, 2001

Jonathan,

If my 'baby' dynos 420-450hp here in SoCal, corrected or not, I'll be a very happy dude, well, at least for a while.
I'm not into racing nor big peformance #s.

If your HP goal were to be as I stated in my initial post, would u have installed a Greddy SP, performance-wise?
I happen to like its looks and the fact that it's quiet and made of stainless.

As always, like your postings. Keep'em coming. I learn a great deal...

Thx,

Jay

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$upraMan

· #8 · Nov 14, 2001

supra_10 said:
Jonathan,

If my 'baby' dynos 420-450hp here in SoCal, corrected or not, I'll be a very happy dude, well, at least for a while.
I'm not into racing nor big peformance #s.

If your HP goal were to be as I stated in my initial post, would u have installed a Greddy SP, performance-wise?
I happen to like its looks and the fact that it's quiet and made of stainless.

As always, like your postings. Keep'em coming. I learn a great deal...

Thx,

Jay

I don't think SP is made from stainless steel. At least not all of it. Also if all you want to get is 420 crank, you should just raise the boost (get a BCC too) and keep everything else stock. You don't even need a downpipe for these type of numbers!

supra_10

Discussion Starter · #9 · Nov 14, 2001 (Edited)

$upraMan,

Assuming u r right, as far as pure HP is concerned, I have the following concerns:
1. I plan on raising boost to about 17psi. Is that sufficient to
achieve 420 crank?
2. If the increased pressure is too hi for the exhaust sys, it may
cause back pressure which might put extra stress on the
engine & screw up mileage. In other words, if the SP or stock
unit can handle desired HP, at what COST?

Brings me to the next question, does anybody know the diameter of stock exhaust?

BTW, I talked to Greddy, and the guy told me that the muffler & tip of the SP are made of SS while the piping is made of aluminized steel. He claims that it won’t rust. Hope he’s right.

Keep’em coming, plz..

Thx,

Jay

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SUPRAT

· #10 · Nov 14, 2001

I think the stock exhaust is 2.5" but it isn't exactly a "pipe", it's stamped steel I think and barely resembles a pipe. I can see why after DP the car "wakes up." Increased exhaust pressure would only be a restriction(issue) with the stock exhaust not the GReddy SP. As long as the exhaust has mandrel bends, it should not be a problem at that HP level. SP is a free flowing exhaust-more so than stock.

$upraMan

· #11 · Nov 14, 2001

supra_10 said:
$upraMan,

Assuming u r right, as far as pure HP is concerned, I have the following concerns:
1. I plan on raising boost to about 17psi. Is that sufficient to
achieve 420 crank?
2. If the increased pressure is too hi for the exhaust sys, it may
cause back pressure which might put extra stress on the
engine & screw up mileage. In other words, if the SP or stock
unit can handle desired HP, at what COST?

Brings me to the next question, does anybody know the diameter of stock exhaust?

BTW, I talked to Greddy, and the guy told me that the muffler & tip of the SP are made of SS while the piping is made of aluminized steel. He claims that it won’t rust. Hope he’s right.

Keep’em coming, plz..

Thx,

Jay

Stock DP limits boost on most cars to somewhere around 15-17 psi. I know a few cars that were able to boost 20+ psi with stock DP in place. Stock boost is 11.2 psi, from what I remember. That's about 300 at the wheels. If you run 15-17 psi you should be right around 350-360 rwhp.

DP will free up the exhaust alot. The turbos will spool faster, boost higher, make lots of power

. If you get a DP, I'd consider a boost controller so you won't have to run 20+ psi whenever you punch it. Stock exhaust is not a major restriction, only the DP is.

Greddy SP will show signs of weather. I have a used one for sale if you want to save money (1/2 price of new). Email me if you're interested.

supra_10

Discussion Starter · #12 · Nov 15, 2001 (Edited)

$upraMan,

"DP will free up the exhaust alot".
I would have expected the opposite--the smaller the DP dia (stock) the less the load/pressure on the exhaust, as less air is going thru.
So what gives? What's the physics behind the above statement?

The weather signs on your SP, are they limited to the pipes or do you see'em also on the muffler/tip? I would expect that it's likely to happen on the pipes as they're aluminized and it could oxidize especially in snow/salt environment. I'm in SoCal...for a reason...

Is that the case?
Which other exhausts withstand the elements better (well, without going into exotic stuff like Titanium, etc.)? How is the GReddy PE in comparison?

Jonathan,

How do the #s translate for an auto tranny?
Also, I understand that u have a GReddy PE installed. Sound-wise do u get every cop's attention from some miles away or is it reasonably quiet (launch & cruise)? Any idea how it compares to an SP?
Have to admit that it may make sense for me to "force" myself to get used to the PE looks...

Suprat,

Do u happen to have an SP? If u do, do u like it? If u don't, what do u have?

Thx everybody. Your input is invaluable to me.

Jay

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$upraMan

· #13 · Nov 15, 2001

Free up exhaust alot as in the whole exhaust system including DP and cat-back. Stock cats are the biggest restriction by far, so by removing them your complete exhaust system would have a lot less back pressure allowing your turbos to spool quicker and build more boost.

SP showed signes of age on the pipes, much like stock exhaust after say 10-15K miles of good weather driving.

SP is very quiet.

SUPRAT

· #14 · Nov 19, 2001

$upraMan, Do you have Dynojet documented proof that the stock cat's are restricted? I have hard evidence otherwise. I know the DP is restricted.

Supra10, The SP is probably the quietest aftermarket exhaust I have heard. In some cases at certain rpm's without DP, it is quieter than stock.

I don't have a GReddy, I have an HKS.

supra_10

Discussion Starter · #15 · Nov 20, 2001

Supra10, The SP is probably the quietest aftermarket exhaust I have heard. In some cases at certain rpm's without DP, it is quieter than stock. I don't have a GReddy, I have an HKS.

SUPRAT,

Any reason to go HKS (model?) vs GReddy PE?

Jay

SUPRAT

· #16 · Nov 20, 2001

Personally I like the deep throaty roar from my car with HKS, but that's me. I don't mind extra loudness. If you want stealthiness, go with PE or TRD Sport if you want slight power advantage and a awesome intimidating deep roar go with Tanabe, Apexi, or HKS. There is an exhaust I have heard personally at Vegas that sounds like a small block V8 with flowmaster on the supra. I am thinking of changing my HKS to this one. It's called ATR. It rumbles at idle like a V8 and roars like a NASCAR at full throttle. It doesn't even sound like a supra. Like you swapped out the I6 for the Lex V8. I practically ran down the guy with it to ask him what made his car sound like that. He grinned and said "ATR Performance" so I looked them up.

http://www.atrperformance.com/index.html

-SUPRAT

supra_10

Discussion Starter · #17 · Nov 21, 2001 (Edited)

SUPRAT,

I looked at ATR's site. Unfortunately, they don't have any info (online) on any Supra stuff. At a minimum I'd like to see a pic.
I ordered a catalog. Will likely take few weeks till I get it.

I attended the last Vegas meet and if there's one thing that I REALLY regret, is that I didn't pay any attention to the variety of exhausts there. Damn!!!! During that meet I still didn't own my Supra and I was totaly unaware of this whole exhaust stuff.

I think that someone should come up with a good exhaust site that would have audio sample sound of various exhaust/DP/cat/HP combinations so we could "sample" before buying one.
Looks-wise I like the new TRD one. Haven't seen it in person, just the pic at: http://www.suprastore.com/newtrdex1003.html
It's 100% SS and looks great (to my taste). Don't know dia/performane, etc.

Thx much for your input.

Jay

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supra_10

Discussion Starter · #18 · Nov 21, 2001 (Edited)

Does anybody know a Supra with ATR exhaust in SoCalif?

Also, anybody with first hand knowledge of the new TRD exhaust? What kind of sound & performance. Is it single or dual pipe? Diameter?
Some details at: http://www.suprastore.com/newtrdex1003.html

and a pic at: http://store5.yimg.com/I/supra_1660_7209955

It's 100% SS and I like the looks.

If you guys know of a link to details page ...

Thx,

Jay :blue:

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supra_10

Discussion Starter · #19 · Nov 21, 2001 (Edited)

SUPRAT,

"I practically ran down the guy ..."

Is this guy from SoCalif by any chance???

Thx,

Jay :blue:

supra_10

Discussion Starter · #20 · Nov 23, 2001 (Edited)

Jonathan,

Here's the situation:
I'm still unsure about the SP.
I had an opportunity to buy a brand new ("spanky new" to quote the seller) PE for dirt cheap so I grabbed it, even though I'm still undecided about actually installing this one. It looks BIIIIIIIIG almost like a rocket launcher...and it sits LOW.
Looks-wise I really want to get the new TRD, however, I still don't have any tech details.
Read a 2 liner about the ATR, but again, haven't seen any pics nor any techs.
Bottom line-- I'm undecided and searching...
Looking 4 a quiet and good-looking, not-in-your-face, hanging-high exhaust with performance equivalent to the PE.

BTW, where in SoCal are you? I share my time between W. Hwd & Agoura Hills.

Thx,

Jay

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