Am I forgeting any mods anyone?

[jibby]

Hello people I have a built 1992 SC400 I have done the following mods and currently like the low end torque and don't want headers and lose that torque, other then that what can I do without opening the engine up and changing internal parts?

Intake- Injen tube/rod millen filter/ heat shield with larger air intake duct. Slightly larger mass air flow/ air disrupting sheet metal inserts.
Exhaust - Megan N1 mufflers on 2 1/2 piping all the way thru, magnaflow cats.
ECU - Apex piggy back switching too stand alone shortly
Dragon torque converter
Supra LSD on 3.07 gearing/lowered going with teins
Electric fan to replace oil driven fan
High volume fuel pump and 100-150hp shot nos sytem
Hyper voltage regulator/ high performance electrical wiring.

I think I covered every thing maybe I have some other small stuff, some weight loss, can anyone of you lexus heads offer me any cost effective horse power producing mods, I believed I covered most. I pushing 475hp I want to see how much hp it will take to blow this stock 4.0L V8 motor, so far it is runnign fantastic. Need more power Scotty!!!

 

[mycarhasposessedme]

currently like the low end torque and don't want headers and lose that torque,

Am I missing something, please explain the above statement.

 

[jibby]

My original post expained all the mods I have done on my stock 1992 sc400 motor, I was wondering what other upgrades or hp gaining mods that are available for this engine that I have not done yet. Again I will list-

Complete exhaust- 2 1/2 piping high flow cat, N1 mufflers, (don't want headers) worried about loosing low end torque.

Complete intake-, injen snorkel tube, Rod millen filter, direct flow air to filter, heat shield.
Nos 100-150hp shot
ECU piggy back (going to go to stand alone, for future engine swaps and airforced induction.
Dragon Torque Converter
Electric cooling fan
High volume fuel pump
Voltage regulator
Supra LSD 3.07 gearing
Teins on the way
Drag tires

On a cold night with the a new nos bottle maybe heated to 1400psi I am pushing very close to 475hp. This car hauls 0-60, traction is my biggest problem, but am getting it.under control, I hope. Back ends are very light on the sc's.

Without opening this engine up is there any other mods out there for my sc engine that I forgeting? I am going to build a 98 sc400 motor soon as a project, but don't want to open up my current running sc400 motor. Was just inquiring. Anyone?

 

[V8TOY]

Do headers lose low end torque? could of fooled me.

 

[jibby]

Yes you gain the horsepower from changing out the headers on the sc400 mostly at high rpm and will lose low end granted you have changed out your cat and mufflers to highflow. In fact I have a friend who put headers on his sc400 and lost so much low end torque he was was forced to switch the differential gearing to compensate for the loss. That is fact! Although he is running straight pipes which is a little different from my curvey 2 1/2 exhaust piping, but based on that experience I do not want change out my headers. As witnessed his car was faster at top end and on the freeway noticeably after the header change. However, I enjoy riding my sc400 cruising or practically idleing at 1500rpm's riding up hills at 40mph in a higher gear, thank you very much. That is what you call low end torque! You hit the gas and get instant power and ecelleration from a dead stop that is if you have changed out your torque converter, you know both wheels start spinning out ridiculously for about 30 yards at full trottle, you roast your rear tires and cause a smoke cloud. Your neighbors get upset, the dogs start barking and every comes out to see what is going on and by that time you are half way down the street, get the picure? Now if I were to get headers on my sc400 I may not be able to experience that sensation anymore, and that would be most upsetting to me. Are you still fooled?

 

[verylost]

How often do you race/drag at less than 3000 rpm? You have the TC. Get the headers .. hehe

 

[mycarhasposessedme]

Can you please give more details on your friends headers and exhaust system-configuration,pipe size etc, as something is wrong with his setup.
A set of properly designed headers combined with a properly sized exhaust system should not loose low down power.
The exhaust is where you will find the torque you are after.
Read some of JBrady's posts in the exhaust section!

 

[jibby]

I race often and do not lose very often, the power band in this sc is at lower rpm's the shifts are quicker and it works just fine, why mess with a good thing? I would love to get the headers and 15 extra hp if I thought it would help my 0-70 times. I bolt off the line, headers will greatly reduce that effect!!!!! Do you people have any real experience or are you all just assuming headers are better for every car? Come on people! Does the term back pressure, or vacume pressure mean anything to you?...He He

 

[jibby]

My friends sc400 had 2 1/2 inch straight exhaust pipes high flow cats and mufflers, a complete custom job. Forgot what size headers he installed, but when it was done he had a significant loss in back pressure/vacume pressure and lost his low end power but gained high end.

I will break it down for you, my 1992 sc400 has the stock exhaust design, I went with the megan N1 mufflers and a magnaflow cat. I installed 2 1/2 piping from the cat to the mufflers, that is my current exhaust setup on my sc400. I recently went to the magnaflow cat and noticed I lost low end and gained a good amount of top end. I dyno'd and tuned no change. I assume the same or worse would happen if I went with headers. I am affraid to change, I really love my low end I am not interested in racing on the freeway. I am a 0-70mph racer. Now maybe I am wrong do you think any type of header would increase my 0-70mph time? I don't think so. Maybe the same, such as slower starts and faster finishes, but not a faster time. I don't know but what I do know si what happen to my friends sc400 as stated above. Please enlighten me on the perfect exhaust setup for my sc400. I do have the complete intake, ECU piggy, DTC, NOS. I would love to have the extra 10-15hp headers bring.

 

[V8TOY]

yes i am fooled cause i got headers done on my sc and i didnt loose any low end torque, i have taken the cats out and got a 3" pipe straight out the back.
Thats my experience anyway...
i can still huss the tires in the dry, when i want to.
And knowing the sc is a big heavy car i rarely dry and race from the mark.

 

[mycarhasposessedme]

Does the term back pressure, or vacume pressure mean anything to you?...He He

Please jibby enlighten us poor simple people with your obvious vast knowledge, I would love to hear your explanations.
Do you race at the track, or on the street against grannys.
Post up some quarter mile times inc your 60ft.

 

[V8TOY]

i would like to hear this...
all ears open

 

[jibby]

Well then there must have been a tuning issue on my freinds car or your making up the story. How do you explain me losing low end torque just by changing out the cat on my sc400 with 2 1/2 piping? Why did Todd at Tm Engineering claim I would definetely need to change the gearing on my differential to get back the low end I would lose from installing headers? Is Todd the engineer mistaken? Did you gain low end by changing the headers on your sc? Or where all the gains at top end and no change at low end? Be specific. Don't you need some back pressure or vacume pressure for these engines? I am more formiliar with small and big block Chevy's then these 4.0 liter V8's. With your set up it sounds like you can roll a tennis ball down your header pipe and it will roll out the tail pipe. He He. Enlight me please, maybe I am being fooled here.

 

[jibby]

I am trying to enlighten myself by posting these threads, and yes I do race and beat the street grannies, Mr. Mario Andretti. I will post my time when I get my drag tires with fatter rims and teins installed probably before the end of this month.

 

[jibby]

Man I created on monster on this thread. Please anyone think myself and Todd at Tm Engineering are incorrect on this header issue.

 

[jibby]

V8TOY I hope you can still huss the tires in the dry or else you should not even be replying to these threads. I can roast my tires (both rears) through the first two transmittion gears. Maybe half a block. I am running on 9.5 rims.

 

[V8TOY]

i have got 285-35-19's and they huss something wicked, im not tryen to start a argument here but i just beleive that headers dont make you loose your low end torque, i have personally done it and it feels better... maybe your mates car was mud.

 

[jibby]

I agree I would love to learn that I am wrong about headers on the sc400, what size headers are in your sc and how loud are they?

It's all good, we can all get excited and testy writing on these threads, that is why there are forums.

 

[V8TOY]

the headers are rowdy as, the pipes is 2" to 2 2bolt flanges and into my 3" mandrel bent pipe wich goes striaght thru to a 4" muffler so its straight thru and real rowdy.
but also have a good intake system i have got a massive pipe from the throttle down to my air filter all custom made.

 

[mycarhasposessedme]

Yes Jibby, I for one am impressed with your big single spinner burnouts on the street, you must be very popular in your area, but you still didn't give us all a lesson on back pressure and vacum pressure, anyway, please go to the exhaust section and read, read, read, then post any of your exhaust related questions there.
You will find a lot of experienced people willing to answer your questions there.

P.S. Do you really own a car, sorry but I had to ask.