SC400's Cold air, Ignition, and Exhaust

[stevechumo]

I'm just thinking about how much horsepower I will gain for doing these upgrades on a 1995 SC400.
1) A cold air system that I plan to cut a hole under the stock air box position and run a full custom intake pipe and its filter down underneat. I might use the Bypass valve by AEM, which eliminate the water sucked in the engine. I believe it'll make more hp than the short ram or stock air box. How much hp will I gain?

2) 2 MSD 6AL ignition boxes that gives more sparks. How much hp will I gain?

3) A full exhaust system including the hi-flow cat-converters in the upper part, with no big cat in the middle like stock, and 2 resonators near the rear mufflers. I will still use the stock headers since I don't want to haul the engine out. How much hp will I gain?

Any info. is greatly appreciated.

 

[Peewee]

1) 5hp maybe
2) Probably 0hp
3) 10hp maybe

 

[stevechumo]

1) 5hp maybe
2) Probably 0hp
3) 10hp maybe

Why would you think no. 2 (MSD boxes) wouldn't make any hp? I heard it would help gain from 3-5 hp depending on cars. I've used a single MSD 6AL with external coil on my Honda and I felt it gained more hp due to the fact that it spinned and screeched the tires on the street. However, it didn't do this with stock ignition. I might be wrong but I tested again and again, and it happened as what I stated.

 

[Peewee]

If all the MSD boxes do is replace the stock coils, then there will be no benefits.
I doubt the stock coils are lacking in spark.

If with the MSD boxes you can increase the timing by a few degrees, then you will probably find a good 10-15hp in there.


Tuning is what makes power on this motor. Toyota have tuned it VERY conservatively.
I put down 200rwhp on the crown log headers (very restrictive) and a restrictive exhaust. It was a manual tranny though. But the ecu was untuned.
I probably would have gotten over 210, maybe 215 hp had I tuned it then (I was getting a new exhaust, so no point in tuning it at the time)

I know another guy who put down about 205hp through an autobox and better headers (similar to SC400), all because he has aftermarket ecu.

This is all up on the 170ish hp these motors normally put down.

 

[stevechumo]

Tuning is what makes power on this motor. Toyota have tuned it VERY conservatively.

I know another guy who put down about 205hp through an autobox and better headers (similar to SC400), all because he has aftermarket ecu.

But tuning the ECU would cost from $850 to $1500 with minimal result in hp gained, which I think it isn't worth tuning the ECU alone, including the MSDs, cold air, and exhaust. So the cost would be more than $2,000 for the gain, let's say around 30 hp. I think the idea could be from my bad previous experience with a tuned ECU, cold air, and exhaust on my previous Honda. What's your opinion? Unless with a turbo or a supercharger set up, then I think it would be worth the hard-earned dollars. However, if for spending around $2 k, I think I could get away with a mild turbo or supercharger setup by doing it myself, which gives me a faster head-to-head race.

 

[Peewee]

You pretty much summed it up there.

Power will not be cheap on this motor.
Its not like a Chev where they have a tuned 450hp version, a happy 380hp version, and a detuned 320hp version. And all you have to do to the detuned one is a set of extractors and a chip and you almost have the happy 380hp version.

Unfortunately this is not the case with Toyota.
A full tune, full extractors/exhaust, CAI/BFI/etc, will net about 70hp gain. Maybe a tad more (80hp) as you have the 2nd gen 1uz (as opposed to my 1st gen)

BUT! the step after this is a set of cams (about $2000AUD), and you should gain another 80hp (after a couple more hours on the dyno tuning).


You have to decide whether that is the path you take, or if a homebuilt turbo/supercharger setup is more to your liking.


Basically either leave it stock, and do things for asthetics (ie, exhaust for sound, intake for looks), or take the plunge, spend a heap of money (how much depends on you, but it won't be a little bit), a take either an FI or NA route.