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SVO Blower Belt Size ?, JLT CAI, Meth?

4K views 9 replies 3 participants last post by  MikeBrally 
#1 ·
Just bought a 98 GT with an SVO Supercharger, SVO Heads, PI Cams, FMS Shorty Headers, Bassani Catted X Pipe, and Roush Side Exhaust setup.

It doesnt make full boost as soon as you hit it, and has a momentary lag, so Im not sure if the belt is slipping off the hit or not (although my experience with blowers has been the belt usually slips in the upper rpms, this is my first roots style though), it's hard to tell too, because it has a digital boost gauge. Could it be the bypass valve is setup to do this stock with this kit? Even with a bit of throttle, it really doesnt make boost, until you are pretty close to WOT.

What size belt does it take with the stock pulley? Also, I know people were getting pulleys for them years ago through ASP, is there a wait for that, or do they have them ready to go? Any chance of say, a Lightning pulley fitting the blower? I know the rib size isnt right, but the belt should work, if the pulley actually fits.

Anybody ever tried meth/water injection with these? I know the 03-04 Cobra and Lightning guys dont have alot of luck with methanol on them, but they have an intercooler stock, this setup does not, and it REALLY hates the heat. Would injecting before the blower be worthwhile?

It still has the stock air tube, a smallish K&N, and stock maf, I wonder if a JLT RAI, 70mm TB, and bigger filter would wake it up? If I did a 90mm LMaf or SCT, I would need to get it retuned. Im debating on what to do.

Whats the max rwhp out of this setup with a pulley, bigger cai, tb, maf, meth, ported by Steggy, etc? 400-425 possible?
 
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#2 ·
Also, trying to figure out what plugs I should be running in this setup. Probably going to do autolite racing plugs, but dont know what heat range for these heads (slow burn chamber style) and the blower.
 
#5 ·
The only thing is, the SVO heads are "slow burn" so Im not sure if people ran different plugs in them or not. The plugs in it are supposed to be pretty cold. I wonder if they are hurting power any.
 
#6 ·
Speeds8erM-1,

I'm running one of the old SVO non-intercooled superchargers on a 5.0L (big bore) modular with P&P NPI heads, Comp Cams, Kooks headers and a dual 2.5" exhaust system in my '97 Thunderbird. I have instantaneous boost at large throttle openings with this setup, so it may be you've got belt slip or some other issue. The belt length with the kit pulley is 113". Make sure you run a high grip belt like a Goodyear Gatorback, and make sure your tensioner is good and tight. If it isn't, try a 1/2" shorter belt.

Keep in mind that the SVO kit was designed to make 6 psi of boost on a completely stock 4.6L setup (factory exhaust system, etc). I was only making about 4 psi with my larger displacement, free-flowing intake and exhaust, etc. I initially changed to a 3.3" diameter pulley (with a 112" belt), then later to a 2.9" pulley (with a 111.5" belt) to get to 9psi of boost. A company named Pulley Boys sells pulleys for the SVO blower in a wide variety of sizes.

There are a number of Thunderbirds with SVO blowers running around, and most are using water/meth injection. I have the Alcohol Injection Systems trunk-mount kit with dual nozzles. It dropped intake air temperature about 60 F and allowed more timing. If you haven't already done so, move your air temp sensor to the intake runner portion of the SVO blower (the "outlet" side), rather than near the MAF like on the factory setup. The EEC needs to know the air temp entering the engine.

I've been running a 3" MAC CAI with a shorty filter, 90mm LMAF, and 75mm TB (which required minor porting of the SVO's inlet). I believe this setup is restricitve and am currently building a 4" diameter CAI setup with a much bigger K&N filter. Unfortunately, going any bigger than 75mm on the TB would be impossible without reconstructing the inlet of the SVO housing.

My setup is making 350 RWHP through a 4R70W, with 375 lb-ft. The tune is pretty conservative, and I believe there is more power to be had. There is a stock displacement T-Bird with the same heads I have making 380 HP with an SVO blower.

A long post, but I hope some of this helps you!
 
#7 ·
Thanks for the info! Have you done anything with the bypass valve? I cant figure out why the car hits some boost right off the bat at WOT, then starts to climb like a centrifugal. I also noticed it making a little less boost the other night, maybe the belt needs to be swapped?

Where did you put the nozzles on yours? My friend is running that same setup on his Vortech GT. How much timing is in yours? The IAT is still near the maf, can I move this to the intake without changing the tune?

Did you make 350 rwhp through a locked or unlocked converter?
 
#8 ·
Speeds8erM-1,

No, I have not modified my bypass valve. Your boost should be nearly constant across the RPM range - that is the nature of Roots type blowers! Mine puts out slightly higher PSI at low-mid RPM than it does at the top end.

My water/meth nozzles are in the intake air duct just ahead of the throttle body. My tune only has 22 degrees of timing, which is why I believe it is overly conservative. The T-Bird guy making 380 RWHP is running 24-25 degrees, I believe.

Not sure about whether moving the IAT requires a retune - I moved mine to the intake runner before the car was tuned the first time. If your GT has the EEC that came preloaded with a tune in the SVO kit, it should be OK as-is. But, I was told by a knowledgeable tuner that it is better to have the IAT downstream of the rotors.

I'm pretty sure the TC was locked for the dyno pulls, given the shape of the curves.
 
#9 ·
I have the computer that came with the blower kit......on a shelf lol. It actually has a MAFterburner and was tuned with an old school Autologic Chip like 7 years ago or so.

22 degrees sounds like alot of timing from what I have seen on blower 2v's, but I guess it depends on alot of things. My friend's Vortech 02 GT with AIS Dual Nozzle Kit is running 19 degrees, 20 degrees only added 4 rwhp, so they put it back to 19.

What are your IAT's like? I would hate to see mine right now, eeek.
 
#10 ·
Speeds8erM-1,

I don't actually have a number for my IAT. The tuner was vague about that when the car was retuned after adding the water/meth system, saying only that it "helped". I'm hoping to add an Aeroforce scan gauge sometime later this year so I can read it for myself.
 
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