trbopooh

Yep, mine is a 400.

I6turbo

iTrader: (1)

Power increases look great!

How do the headers effect exhaust SOUND? One complaint with my cat-back setup (still on the stock manifolds) is that the exhaust note isn't well defined -- kind of like you can't hear the individual cylinder pulses the way you can in a beautiful-sounding exhaust like a Ferrari or some such vehicle where the engineers have paid attention to the sound quality. So, I'm wondering if the headers significantly improve the exhaust sound in that regard???

trbopooh

The headers don't really increase the noise level at all.

SCV8

Brand "F" doesn't do V8s the way that most do; they have a 180 degree, or flat crankshafts which gives the cars a raspy sound like two four cylinders coupled together.
I've heard some pretty nice sounding Mustangs that sound like our cars with modified exhausts however.
Glad the project worked out, I wasn't very impressed with the Aussie headers given the hassle for US people to get them and all.

GILLEXUS

iTrader: (14)

Trbopooh,
I forgot to ask you do you know if your installer removed the engine mounts to do your header in stall??

trbopooh

Yes, I had to unbolt the engine mounts to get to the headers more easily. Wound up finding out that engine mounts were bad and needed to be replaced. They looked very similar to lexolife's engine mounts. Now the car doesn't shake and feel jumpy while shifting.

GILLEXUS

iTrader: (14)

Thanks. That sounds like the way to go. How many miles on your motor? What did the motor mounts cost?
How many mounts are on the GS motor 4??

trbopooh

I have about 92,000 on my motor. I unsure of how many mounts there are on a gs, but I replaced the two where we had to unbolt. The mounts I think are around $90 a piece.

GILLEXUS

iTrader: (14)

Thanks I'll check mine out when I do my install.

TexasLex

Got my 1994 SC400 back from the shop last Friday after having the headers installed along with a 2.25" exhaust system. Also, had the T/C changed, LSD installed and the Apexi S-AFC tuned on their dyno. Picked up 15 hp and 2 pounds of torque and the power band is much wider and smoother now.

However, the car has a horrible exhaust resonance problem - well, I think it's horrible, everyone else thinks it sounds perfect. Anyway, the car will be going back in once the additional hangers, brackets and different mufflers come in. Also, I think there is a vacuum leak related to the EGR removal that may be holding back the motor some.

I saw the dyno sheets for the GS with N/A, but what HP and Torque improvement have N/A applications realized from the headers?

JBrady

Hmmm... this while an improvement is less that expected. Do you have any exhaust pictures? Do you have the dyno sheet in a postable form? Did you go with X or Y pipe? You say much wider and smoother can you be more specific. SRQ400 feels a DRAMATIC inprovement in power and torque on his 99. He has not dyno'd but the low speed on up is to him very different with much better throttle response through out. You also made many changes at once. I am interested in the layout of your system.

TexasLex

I will try to remember to bring the dyno sheet into the office to scan and post tomorrow. By the way, I was at 195 HP max before the new mods.

I had my digital camera with me every time I went to visit the car. When I was finally able to pick it up they had it sitting on the ground already. Then when I went back to check out the resonance I did not have it with me. However, I will certainly get pics when they lift it up to put on the new stuff. The mechanic said the high stall T/C is hiding some of the HP increase, but I had not heard of that happening before.

They did do an incredible job fabricating the exhaust system using mandrel bent 2.25" SS pipe sections and TIG welding. The system has a flex pipe between each header exit flange and Carsound cat, then the pipes go smoothly into a Magnaflow "X" pipe. When they exit the "X" pipe they go into Magnaflow resonators then branch off to each side where they finally flow through the (currently) Borla straight through mufflers. There was a twin turbo 350Z show car on a rack there that had an Invidia exhaust system and most of the welds on mine looked better than his did.

There is a strange hissing sound coming from the left side, but we cannot find any trace of a leak. So I took it to another tuner shop that does MIG welding and they first thought it was an OEM job, when they realized it wasn't they then said it was an awesome job and could not find a leak either. I think the hissing is a vacuum leak that is causing the power to not be as strong as it should be. I am going to email Lextreme for the EGR install instructions today so I can check out to make sure everything was put back right.

Also, under hard acceleration I am hitting the rev limiter before the transmission shifts to second. Any ideas here?

BA_GS400

iTrader: (1)

You or your dyno guys may know this already, but, sometimes a can of brake cleaner can help find those vacuum leaks. Just start the engine and spray it liberally around in the suspect area's. The engine rpm's should change slightly if you spray on the leaky area.

TexasLex

Thanks for the tip, I was hoping to not have to do that b/c my engine compartment is detailed perfect. Could spraying the cleaner take the paint off or mottle it? I was going to have them use an unlit propane torch - probably more dangerous for the whole vehicle I realize, but at least it will go out with a bang if something goes wrong.

Lvangundy

I beleive your rev limited problem in 1st is due to your TC and 3.76 LSD.

I think someone lowered the stall speed and resolved this. Otherwise you'll need to either get rid of the rev limit, remove the 3.76 unit and use the stock 3.23 with the TRD gears, or toss the TC or the 3.76/LSD completely.