The 170-180rwhp doesnt surprise me at all. It may seem low, but we make plenty of torque starting at 2000rpms which is why we do good on drag races compared to the IS (which may dyno higher). This is why many people see such a large gain from a torque converter. My SC shifts so smooth I cant even feel it if Im not flooring it, as Lexus probably wanted to design it, but you have to make sacrifices, Luxury or Speed.

Question about the X-Pipe, what kind of X did you use? Did you buy a premade stamped out X they use on Mustang X-pipes, or did you have two pipes welded together where they cross?

How much less do these aftermarket mufflers weigh less than the stocks? Discount Auto has Cherry Bomb Turbo Mufflers for $17! They may not be the best quality, but they should do the job and the price doesnt hurt

 

Does DirectQL have a 5-speed or automatic?

 

I believe it is an automatic.

 

I'm still banking on more rwhp{about 193 - 205hp} based on the standard results of 20% loss with a proper running and NOT worn out engine. I have to see some hard DATA before I give up on my quest of more rwhp...

Does anyone have any dyno info on the SC4?

 

007 tell me where those smog sniffers are on the freeways and I'll go cut their cords
I might be crazy, or fooled by the noise, but my car will put you in your seat if you stomp on it. Strong, well maintained engines are key- my car has been serviced meticulously, the people at the dealer remember the previous owner and said he was an absolute perfectionist. It shows, and did in the condition of the car when I bought it, which is why I bought it. Some people might buy one of these cars, or get it as a hand-down from a relative and the car could be worn out, or be in need of a rebuild or a major tuneup.
The mufflers are probably 15 pounds lighter, at least. Cherry bombs would be hilarious on an SC :P My crossover happens in a large custom coupling before the cat.

 

Aaron's SC400 got 175 hp at the wheels - a common figure. To convert kW to hp, multiply kW by 1.34.

See his full write up and dyno graphs on my web page.

 

Ikon,

True that condition of the car does make a big difference in the engine performance. However, in the quote you mentioned, the car made 177 rwhp after the tune up. About the same as mine made. I know that the powertrain loss is too high, but seems to be what we are dealing with. Some ideas to reduce that loss would probably be a good area to look into. I have not yet heard of any SC400 dyno greater than 180 rwhp stock. In fact, except for the Mech tech twin turbo, I am not aware of any numbers for that car greater than what is reported at stock.


Matt1784,

I bought my x-pipe from magnaflow. It is stainless steel and designed for max flow. You can buy it over the net at
www.promuffler.com. They have the best prices I have seen yet. I went with the 2.25 in, but some are suggesting 2.5 in pipe all the way through. Don't go with the glasspack. They are going to sound terrible. Find some nice straight thru stainless steel mufflers and use them. if you remove the cats, you will probably have to add some sort of resonators, this is my next step.
Raj

92 SC400 111000k

 

Raj, the car I was referring to is a SC300(177 rwhp after tune up... "DirectQL's" SC3 from Chicago... If a 300 can do this a 400 should be at least better in terms of rwhp than a 300...( At leas 10rwhp or so more, I would think..)

UZZ32, I can not say enough about the quality of your home page it is a true Soarer/SC lover's site!!!

On one your links you had this way to convert RWHP the way the Gtech and other devices measures rwhp...

***http://www.smokemup.com/utilities/calc/hp_mph.cfm

* If you enter the weight of the SC4 which is 3650 lbs {SC3 is 3549 lbs}

* Add the weight of the driver (I'm around 160 lbs)

So the weight is 3810 lbs

* Add in trap speeds... I'm adding 92.9 mph (I got this speed from a Motor Trend).. The 0-60 was 6.9 and 1/4 et was 15.0...

* factor in the 20% drive train loss

* compute it and get the results

Results are *** 202.77 HP at the wheels... ***253.46 HP at the fly wheel... About what I was told before, and about what I've been saying... Plus this is the "standard" way of computing too...

Plus on Aaron's dyno article, this is a quote from the article on your page.....

***[Quote from Aaron Elliot dyno run article] - "It was not exactly cool in the dyno area. The roller door you can see in the pics is the only entry for cold air. This may have affect the result, but the Dyno is supposed to compensate for that. The fan they used moved the air, but given the relativly small amount of intake space on these cars, it probably was not quite enough... The intake would have been gulping warm air, and the temperature sensor was in the duct leading into the radiator, which I noticed when they were unloading it! You can see temperatures in the files." [Quote end]

One more from your site...

***[Quote from YOU on your website about the acceleration results] - "Then go to this site: http://www.smokemup.com/utilities/calc/hp_mph.cfm
Out pops the hp at the wheels. I got 138 km/hr going up hill, 144 km/hr back the other way - average of 141 km/hr (divide by 1.6 to get mph) = 87 mph. Mass of 1880 kg (times by 2.2) = 4145 lbs, out pops "185 hp" or 138 kW at the wheels - sounds about right. If you don't have an active then your car will be at least 100 kg (220lbs) lighter than mine." [Quote end]

You quoted 185 rwhp in a 4145 lbs Soarer with an "active suspension." Plus these are not present on the 3549 - 3650 lbs lighter weighing US spec SC300 or 400.

With that said, I and the other SC4 owners should still expect to see at least 195 - 205 rwhp in a lighter weighing(by almost 500 lb without driver), strong running stock 92' - 97' US spec. SC4... If not, I'll still love it any way...


The Ikon

 

Ikon,

I can't argue with your math. I guess I am only reporting what I have noticed. I recently used the Gtech with my new setup and got 0-60 6.5 secs, 1/4 in 14.7 @99. Maybe the G tech was inaccurate because using the "smokeemup formula", i get 256 rwhp with 321 at the the crank. I think it is clearly overestimating trap speeds, because that seems unreasonable. I guess you have to take these measurments with a grain of salt. I also think the site is overestimating power. I tried it using numbers for a 97 gs400, ie wt of 3900, et 14.5, per car and driver and got 250 rwhp. Seems like swift racing tested one of those at 225rwhp.

Raj

 

Even with an X-pipe, no cats and just stock mufflers you think it will be too loud? From what you put about rwhp, the amount of power from just the mufflers seems quite small for the price.

 

Also what size cat back piping and X-Pipe should I use? Many of the V8 Mustangs are using 2.5" X-pipes and was thinking of going with that.

 

Matt,

Using the x-pipe, (I used 2.25 inch) with the stock mufflers and rear resonators will not be too loud. I had a set up similar to this just before going to the cat back. I don't think that changing the rear mufflers seems to be making much of a difference despite the expectation that it should.


Raj

 

I'll have to agree with you 100%... Your times are getting quite impressive..

Do you have any pics of your set up? I'm still unsure about the exact way I want to do my exhaust piping or I may leave them stock minus the resonators and add dynomax ultra flows and a high flow cat set up like MadMax...

That X pipe set up seems to work on 300ZX(I had the TriFlo X pipe set up on my 300ZXs)... I've seen the H pipe work on Stangs and such for years...

I wonder which would be better on the SC a "H" or "X" pipe set up?

 

Ikon you raise some valid points.

The terminal speed estimates are good for seeing if your mods are heading in the right direction and are noticeable.

Sometimes quoting peak power only is misleading - it is the area under the power graph that gives the biggest on road feel - the larger the area the better. Two cars having the same peak power can be totally different on road, not just the torque but where the power is made. V8's are great for having useable power across a spread - most of my driving is done below 3000 rpm - I just ride the torque curve, there is enough power down there to cruise around.

The easiest test I prefer to see if anything I do makes a difference is roll-on times in 2nd gear. I use 30-110 km/hr in 2nd gear (ECT switch to power).

The difference between a 13 degree Celcius (55 F) and a 20 degree day (68 F) doing this run was about 0.2 seconds. There may be other factors but I tried to keep the conditions constant.

Disconnecting the battery for 5 minutes (or removing the ECU fuse) saw the times increase by 0.3 sec and then improve by 0.2 secs (a spread of 0.7 secs) over 5 runs - is this an example of the ECU learning?

Doing the terminal speed calculation on the road takes into account any improvements made to a cold air intake- a dyno run doesn't have enough air flow to mimic on road conditions. I haven't done a dyno run on my car - it would be interesting to compare the dyno to the terminal speed estimate calculation method.

When you get your dyno run Ikon can you ask for the data files on disk as well as the graph? Then we can start plotting the runs of different cars with different mods on the same graph and see if any patterns emerge.

Other things to note when doing your dyno run are:
1. Type of dyno.
2. Engine temp - is car fully warmed up before run
3. Temp sensor probe position (in airbox or hanging on wall)
4. Ramp Speed - affects how quickly a dyno run can be made and shape of power curve. Note only the speed but whether it was a one-way ramp only, just ramp up is quicker. Usually best to ramp up and down and take an average.
6. There is an extra correction function on some dynos that move whole graph up and down
7. Bonnet up and bonnet down make a difference as well.

Same car, same dyno, same time, an operator can give you different dyno graphs. Sometimes a person gets a before and after dyno graph by the same place that performs a performance modification to their car - the less honest are able to tweak the dyno to give a bigger improvement on the dyno graph and say "there you are mate - I told you it would work!"

You would hope this wouldn't happen but the seven things listed should be kept in mind.

 

Oh no not an X versus H debate :eek:

From what I understand the H is designed to equalize pressure in each bank, while the X also helps with the exhaust pulses and backpressure to get more intake charge.

Over on Mustang Boards, the Guys like to run 2.5" H or X-pipes. It seems according to trial and error, the X pipes tend to have good performance with straight through mufflers (like our stock ones), while H pipes tend to do good with baffled mufflers.

Many mustang guys are running offroad X-pipes (no cats on offroad pipes) with just dual aftermarket mufflers and they dont say it is too loud. I dont care too much about my car being loud, as long as it is legally in the limit (although cops around here dont bother you too much if you have a nice sounding V8, just the little riceburners with their beercan exhausts get bothered a lot).