300hp from "stock 250hp"

[do92sc400]

How is it going. Wondering what it would take to raise my horsepower from the supposed lexus rating of 250-to a more pleasing 300 flywheel horse rating. Problem is that My sc400 is also my daily driver outhere in California, so I need to keep my street legal. Any help please?

I am planning on adding a supercharger in the future. But for now would like to make enough power to smoke or atleast go head to head with a new 350z or a new g35. A while back, I was beat by a new 5spd Maxima (granted I made the mistake of running low ocatne gas as well as hade a psssenger) and it has been bothering me ever since. Lexus (Toyota) is the best car maker ever and would like to prove that a 92 sc400 can kick the crap out of anything new short of a Corvette.

:feedback:

 

[JBrady]

Actually, the horsepower is more like 230. The factory overrated the early engines. They corrected the problem in 95-96 but you need about 70hp to reach your goal.

BFI, headers, quality 2.25" exhaust and proper tuning should get you close. The previous with camshafts and MILD porting should surpass your goals.

 

[Peewee]

As above, you'll need a decent exhaust, and piggy back ecu tune to reach the goal.

 

[Anaema]

weight will be a big concern four you. im pretty sure a SC 400 is a couple hundred pounds heavier than a 350Z or a G35. you can make the car street legal and powerful with some highflow cats and a custom catback exhaust system. along with the ECU tuning and a better intake.

 

[jibby]

Dude you sound like me one year. I have a 1992 sc400 and just look at my setup and you will be as good as it gets with the basics. I live in Ca. so I know all about smog. This is what I would suggest and in this order for performance-

1) Dragon torque Converter, or send in your stock TC to Lextreme, I went with the dragon and still smilling today. Dragon T.C. $1300 installed, go lextreme to save $.

2) Go with a highflow cat, (magnaflow) and get high flow mufflers (I went with megan R1 racing straight thru mufflers). Noisy at high rpms quiet and deep sounding at low rpms no tickets so far for exhaust noise. If you hate noise look into a quietflow mufflers it is truely quiet and flows well, have one on my LandCruiser. That should take care of your exhaust and not break the bank. $600 tops

3)Go onto intellexual.net and check out the intake they describe for 1992 sc400 it flows the best and it is cheap. $50

4) You can open up your air/fuel ecu flow with a good piggy-back ECU, you need to get that installed at a high performance repair shop. I had mine done at Tm Engineering and it fouled and that one was an Apexi piggy back ECU. Greddy-E-manage and others I would try instead. Warning you will notice a hit at the pumps after install. Should give you around 15-20hp. $400


That is the norm for upgrades- if you want to keep going which I assume you will these are a few other tips.


5) There are other smaller mods electric fan (frees up room for air forced induction), and other small electric upgrades to free little hp, air intake inserts, etc....

6) If you want to really step it up go for a set of Kelford cams 40-45hp but not cheap after install I would guess $1500.

7) I have a 100hp dry shot nos system that isn't too pricy either and gets the car really moving. $1000

Anyway good luck!!!! Shop ebay to save on some of the stuff?

 

[JBrady]

Go with a highflow cat, (magnaflow) then 2 1/2 piping from the cat to the mufflers (from the stock 2" piping).

Jibby, if the stock cats are in good shape you will not gain by going to a single. I have seen you recommend 2.5" pipe here and elsewhere... honestly that is TOO large. The smallest pipe that will support the power is best. Bigger pipe slows velocity at the expense of low and mid power. I know of a turbo SC300 running 10.40s at apx 140mph that actually has dual 2.00" pipes!!! I was shocked. Turbo cars are one of the exceptions to the large pipe rule as it is hard to overpipe a turbo. Still, this is interesting to say the least. Actually, consider how many HUGE power Supras have a single 3" system. Dual 2.25 actually has more flow area than a single 3.00. Dual 2.5s is heavier, costs more, harder to route and hurts low and mid power.

 

[SCV8]

Yup, also muffler design is more crucial than the pipe size, to an extent of course.
All of the stock U.S. spec SC mufflers are straight thru, no baffles, so that's a bonus, but the stock system has a bottleneck where the down pipes come together; they pinched the tubes at the "Y".
I am making well over 300hp w/the stock pipes, but using a pair of straight 2" pipes patched in between the down pipes, and the resonators that are just in front of the rear axles. The cost was $60 to get the job done, with a short crossover where the "Y" used to be, and unless I made the step up to some nice headers, the system flows great.
The piggyback ECU with timing control is a help too, along with a huge air filter, ported MAF, some headwork.

 

[jibby]

JBrady, I know you are the exhaust pro and design the awesome S&S headers, y and x pipes, etc. I will just say this is what happen I when I tried a few things with my 1992 sc400 exhaust-

First off I went with the two straight thru Megan mufflers on the stock exhaust, the change out of the mufflers really made a difference, and I felt a decent and suprising hp gain. Secondly I then went with the bigger exhaust pipes from the Y cat to the mufflers to match the same size as the pipes from the headers to the Cat, felt little more hp at top end mostly, but not much but noticeable. Thirdly I then I went to the magnaflow Y high flow cat that resembled the stock Y design catalytic converter and felt another kick at highend. I Looked at the 1992 Sc400 original cat and noticed it was clogged and very restrictive in comparision to the new magnaflow cat. This change again was very noticeable at top end hp gains, and actually suprised me. I did not expect to even feel a gain but I did. I started then experimented with different mufflers and exhaust sizes once or twice and after wasting money and time I determined the best exhaust flow for my 1992 sc400 while keeping the stock design X in place was what I idid and explained in the above post.

Now if you have better exhaust flow setup in mind then what I did and have seen them work better, then I am all ears and eager to learn. Now I am not an exhaust expert but I know you can also go with Headers and straight 3" exhaust pipes all the way back and go all out, aswell. Keep in mind these sc's have to get thru smog as well in California. So John tell me from experience and in detail if you have the time once more what is the best exhaust flow setup for the 1992 SC400 which resembles the stock X setup. What sizes piping and wear, cats, mufflers etc, flows the best..? Because I really think I have a good thing going on my car, and if there is something alot better I would like to know.

 

[jibby]

These are not the greatest pics but this is what my exhaust looks like today. Straight thru mufflers, 2 1/2 piping from manflow highflow cat to the mufflers. It all flows fantastic! Headers are next!!!

 

[jibby]

Wider rims and tires are on the way, pay those skinny's no attention please!!!

 

[Anaema]

skinnies :O!! NO!!!!

 

[340i]

a mandrel bent exhaust will flow a bit better too, so should make better power for not too much more dollars.

 

[do92sc400]

THanks for the advice. Jibby, what are you running 0-60 mph wih that set up (n/a). Also,will the kelford cams comply with California smog. My ultimate goal is to run sub 6 sec 0-60 or mid to low 14 sec quarter mile (although thirteens would be nice) before I decide to run nitrous or go with a super/turbo charder. Need to heve permission from my accountant/warden (wife) to go that route. Lucky for me she loves the sc400.

 

[jibby]

No problem do92sc400....

I have never actually timed my cars speed, because I keep adding something here or there to change it. I can tell you with nos at full blast my car runs a little faster then a new stock BMW M3 0-60mph, and just a bit slower then a new corvette. Traction was my main problem when I raced the new vette, however once we were both got going I stayed with it. Those vettes really grip off the line in comparison to my sc400.

Without the use of nos my car is exactly as fast as a stock new Nissan 330zx 0-80mph. As I raced one about three months ago no nos. I expect my car to run faster with my new 10.5 rims and tires, and once my headers are in, I can't wait....

In regards to my skinny's, those rear tires are from a stock sc430, so they are not exactly skinny's but not fat either. Most upsetting.......

340i- I do not know what the mandrel bent exhaust is, please explain.....

See ya-

 

[SCV8]

Jibby, are you running a "wet" N2o setup?
Stock injectors?
A mandrel bent tube has a constant cross-sectional dimension, no crushing from the bending process, what is likely is that even though your system is 2-1/2", the muffler shop bender has closed it down just a bit, which probably helps you to gain some torque, being closer to 2-1/4" in spots, and limiting the flow to a pipe with that smaller,constant size(but costing WAY more); working for you, in other words.

 

[jibby]

SCV8- I am running a dry nos system, with stock injectors, high volume electric walbro fuel pump, autolite nos plugs. Also piggy-back ecu to help tune air/fuel ratio for nos.

Yes I had the muffler shop bend the piping for fitment and your statement makes complete sense, the bends would be smaller then the 2 1/2 piping, wow, never thought of that....Thanks.....

Since you sound like you know what you are talking about can you offer me any better ideas for my exhaust setup? Headers are coming very soon and on order.....

This is my nos pictures-

 

[Anaema]

No problem do92sc400....

I have never actually timed my cars speed, because I keep adding something here or there to change it. I can tell you with nos at full blast my car runs a little faster then a new stock BMW M3 0-60mph, and just a bit slower then a new corvette. Traction was my main problem when I raced the new vette, however once we were both got going I stayed with it. Those vettes really grip off the line in comparison to my sc400.

Without the use of nos my car is exactly as fast as a stock new Nissan 330zx 0-80mph. As I raced one about three months ago no nos. I expect my car to run faster with my new 10.5 rims and tires, and once my headers are in, I can't wait....

In regards to my skinny's, those rear tires are from a stock sc430, so they are not exactly skinny's but not fat either. Most upsetting.......

340i- I do not know what the mandrel bent exhaust is, please explain.....

See ya-

'Vettes have some crazy fatass rear tires.

 

[do92sc400]

Jibby, what nos system are you using?Also, were are you injecting the nitrous into. Before or after the maf sensor?

 

[jibby]

I am using a 100hp+ dry system, the nos bottle mounts in the trunk (10lb and 15lb bottles), the arming switch is mounted in the center consel inside the car. If you look at my engine picture closely the nos cylinoids can be seen at the upper left side of the engine they are blue in color. A steel braided line then travels from the nos cylinoids to a drilled hole in the front of the throttle body. If you look closely at the throttle body above the intake snorkel tube you can see it, it is a small steel braided hose and then a blue nut can be seen that bolts it into the front of the trottle body... This really is not a complicated setup at all. However, in addition to the nos system you will also need to install a high volume electric fuel pump (like a walbro) and cool running temp nos spark plugs.

In conclusion, Nos is nice and gets the job done however if I could start over I would have preferred to supercharge or turbo as you would not have to hit a button every time to launch, you would also have controlled accelleration, and not have to recharge the nos bottles at $40 a pop maybe ($120 a month for me, but I ride the nos all the time). I can say Air Forced Induction is not cheap either- $$$$$$, and maintenance and tweaking is to be expected more frequently then nos. If you have deep pockets, time and some smarts, I would definetely supercharge or turbo up to 400-450hp....With maybe an Eaton S.C.......

 

[Red Supra]

Nitrous would be the sure way to get your goal without modifying anything. A 100hp single nozzle wet kit would be the way to go.