Suggestions to complement my Supercharger upgrade

[Blown3000]

Looking for suggestions to take my supercharged 3000GT up a step or two. Currently running a Thomas Knight supercharger system using an FMU for fuel control running about 6 psi of boost. Like to focus mainly on simple motor or motor accessories. Nothing that will have any major impacts on fuel mileage, maintenance, or reliability.

[Dbeltran24]

Pulley?

[Blown3000]

Pulley?

Supercharger or Crank? Supercharger is 2.5 Crank is stock.

[ibsorgn]

Looking for suggestions to take my supercharged 3000GT up a step or two. Currently running a Thomas Knight supercharger system using an FMU for fuel control running about 6 psi of boost. Like to focus mainly on simple motor or motor accessories. Nothing that will have any major impacts on fuel mileage, maintenance, or reliability.

I would suggest that the next logical upgrade would be to replace the exhaust system with a less restrictive one. I installed long tube headers first, then replaced my OEM exhaust system but I believe the greater improvement was seen with the larger tubes and smoother flow through muffler and resonators. Warning, Because of the exhaust mods, you are most likely going to see the engine run leaner, and at your boost level using the FMU, you will likely be at the end of what your NA fuel system can handle.

[Blown3000]

I would suggest that the next logical upgrade would be to replace the exhaust system with a less restrictive one. I installed long tube headers first, then replaced my OEM exhaust system but I believe the greater improvement was seen with the larger tubes and smoother flow through muffler and resonators. Warning, Because of the exhaust mods, you are most likely going to see the engine run leaner, and at your boost level using the FMU, you will likely be at the end of what your NA fuel system can handle.

Wrote to you a while back but your email address got kicked back. Glad your back. Car is running very well and I thought I might take another performance step. Anything special concerning the exhaust system, building, parts, size etc?

[ibsorgn]

Wrote to you a while back but your email address got kicked back. Glad your back. Car is running very well and I thought I might take another performance step. Anything special concerning the exhaust system, building, parts, size etc?

My Internet carrier changed and I've been having some trouble for the past few weeks with receiving mail addressed to my old provider. To your question of an exhaust system, I pulled my entire system out and replaced it. I based my exhaust plumbing off a Flowmaster 40 with a single inlet dual outlet muffler. I believe the inlet was 2 3/4 or 3" and the outlets were 2". I mounted the flowmaster around the same location as the old OEM resonator. The system was way too loud, In fact it sounded louder than running straight out the headers. Resonance was so bad that it felt like I was driving inside a 50 gallon drum. I then decided to add a pair of short glass packs (12" long), just before the exhaust tips. Must have killed the resonance by 75 - 80 percent. Really nice throaty tone but, for me it was still too loud. My final mod was to add another 20" glass pack before the flowmaster and that did the trick. Maybe I should have tried that first but I didn't think about it. On the down side I lost a stainless steel system which are quite expensive however my flow through system cost me less than $325. Sure it won't last as long as those $1000+ borla systems but it sounds nice and performs very well.

BTW, one fellow mentioned "Pulley?" I don't know if that was a question or he was suggestion a change to increase boost. Don't increase boost without preparing for fuel upgrades as your FMU is nearing your NA's fuel capabilities. More on that later if you wish to discuss.

[Blown3000]

Would you recommend headers or a better downpipe. Also what type of headers did you use.

[ibsorgn]

Would you recommend headers or a better downpipe. Also what type of headers did you use.

They make some pretty nice downpipes, and that is a bottle neck area for these cars. I don't have any experience with down pipes so I can't really talk intelligently about them but maybe one of the forum members will reply. I think, if you have the money and time, a good set of stainless steel long tube headers would be a wise choice. I put on a set of OBX racing headers and am quite happy, however I wished that I had installed fore and aft O2 bungs before I hung the steel. The OBXs ran me less than $400 and they use 3/8" flanges, 16 gauge mandrel bent 304 stainless steel which is about as good as it gets. Workmenship looked well. Don't think that paying any more for big name tubes are going to buy anymore quality. A good flow through exhaust system is worth 6-8% increase in torque and hp so it is money well spent IMHO.
p.s. expect your motor to run a little leaner

[3000gttom]

assuming the manifolds flow ok you will possibly make more power across the rpm range with a downpipe because the headers will flow backwards at times and you dont really need to take advantage of scavenging when your boosted

the next thing to do would be to upgrade your fuel system and get a good tuning setup with fuel and timing control

adjustable cam gears would also be smart (or maybe switch to vr4 exhaust cams which may be cheaper), you could take away overlap and keep from blowing air and fuel out the other side of the engine which would make more power and better fuel mileage(and better emissions if you have to test for emissions)

idk what kinda intake your running but the n/a runners probably are less than ideal for a supercharged setup....maybe run a big plenum going all the way to the lower intake manifold so the harmonic oscilation doesnt really hurt you too much

[Blown3000]

Thx 3000GTTOM, Interesting point concerning the downpipe and I will keep that in mind when I make my final decision on the exhaust system. I know that upgrading my fuel system will need to be address but after thinking about things I will leave that area for a future upgrade. However I'm all ears for ideas. I should state that my objective for performance is to create a reliable, maintenance free DD which will still offer high 20s mpg. I have no intention to race the car but want to create enough power to make it stand out from its peers. Also I want to stay away from internal modifications.

Oh, the intake I'm running consist of a large plenum attached to the lower intake manifold. The supercharger is mounted on its side with the blower exiting directly into the plenum.