Doint it from Behind!

[69dejavue]

http://i.b5z.net/i/u/1473169/i/Magazines/stsmmff.pdf

 

Placing the weight in the rear with less front end bias, better handiling, better traction, etc. Anyone have experience with this?

[68fastback]

Have no specific insight on the STS, so just some thoughts...

 

No doubt in my mind it will make good [peak] power and IAT2s should be very good with all that intake plumbing but for a streeter it seems somewhat inappropriate. The weight adds are in good places but there would seem to be so many potential leakage/corrosion/failure locations over time that I don't find it appealing overall -- Rube Goldberg would be proud

 

Manufacturer claims it makes more power-per-#boost than any other appraoch (my paraphrase ...likely a surrogate for good IATs) but dyno support that statement only with a really 'peaky' torque curve that comes on late (looks 4250rpm or so?) ...a dubious benefit ...seems possibly better suited to a track car with a hi-stall torque converter and a built motor that can take the boost turned up -- else why carry that plumbing weigh when much smaller and more responsive turbos (or turbo) and big heat-exchanger would seem a better match for the street. Besides, it's broad area *under* the curve that matters, not 'peaky' and 'late' torque. The real beauty of turbos, imho, is *big* boost to make *big* power that effectively offsets the disadvantages of a turbo's typicaly 'late' torque curve with a high-stall auto trans.

 

Another consideration for a streeter might be that when caught in heavy rain, even with baffles (not just "mudflaps" the kit comes with), intakes that far back on a car would seem to have to be sucking in a wickedly-atomized brew of whatever water and water-soluable and suspendable road gunk the front and rear tires froth up (I envision a car driving by at freeway speeds with all that grey froth billowing out of the wheel wells and the intake sucking in the atomized brew that possibly makes it not realistic for a daily driver but no prob for a track car? Rain/puddle froth can be a real consideration for traditional fender-well CAIs used in heavy rain at freeway speeds and those typically use the factory intake location in *front* of just *one* front tire. This rear-TT solution would potentially seem to be considerably more problematic under similar conditions?

 

Dunno, it just seems like a long way to go for nice IATs on a streeter but with many potential impracticalities/drawbacks f...or modest results -- and a fairly big price too ...as well as a pricey install, I would guess, compared to other solutions.

 

For less money I'd think a fixed-displacemnt S/C with early, instant, big and broad torque, is a better street solution. Are turbos a bit more efficient? Let's assume yes (long discussion) so why not a right-sized single/dual turbo iwith large heat-exchanger then ...and without all the more vulnerable under-vehicle intake, oil-lines, exhaust plumbing/pieces, etc with seemingly more and new potential failure points? ...for just-ok results.

 

But wait, isn't Ford going to GTDI for efficient boost? Yup, but those are sophisticated communicating pieces tightly-managed via the PCM -- i.e. an integrated amd dynamic powertrain solution.

 

Just some thoughts.

[GT500-07]

too much plumbing and loss of Turbo efficency mounting them in the rear of the car like that. looks like a STS system. then again it depends on what goals are when doing a forced air induction system. my goal is to get 500+rhwp on the stock 4.6 3v. we're running a smaller Turbo that should spool up around 2500-2700rpm's. with a little luck it hits the dyno tomorrow. Dan, you going to like stage II of this project, 4.6 3v Aluminator with a possible compound boost system. what are you thoughts on the TVS vs the Ford racing Whipple? I'm running a ported TVS on a GT500 with over 700rwhp.

 

http://s221.photobucket.com/albums/dd174/a...nt=IMG_3780.jpg

[69dejavue]

Dan, actually it stated this turbo produces full boost at 3,000-3,500 rpm and makes more HP at 3,800-4,000 rpm than most SC. I am certainly no expert on turbos or SC.

 

500 RWHP to a stock 4.6 3V? For how long? Again, no expert but I would think you must have in excess of 12-15 pounds of boost and that is a lot for cast pistons and powdered rods.

 

Concur there is a lot of plumbing on the turbo and having an oil line from front to rear and back to front would concern me. But the title of the article certainly captured my attention! I am also curious how it would sound with the turbos so close to the exhaust.

[FordRocks1]

Dan, actually it stated this turbo produces full boost at 3,000-3,500 rpm and makes more HP at 3,800-4,000 rpm than most SC. I am certainly no expert on turbos or SC.

 

500 RWHP to a stock 4.6 3V? For how long? Again, no expert but I would think you must have in excess of 12-15 pounds of boost and that is a lot for cast pistons and powdered rods.

 

Concur there is a lot of plumbing on the turbo and having an oil line from front to rear and back to front would concern me. But the title of the article certainly captured my attention! I am also curious how it would sound with the turbos so close to the exhaust.

 

 

 

Here are some sound clips.... http://www.ststurbo.com/mustang_sound___video

[GT500-07]

"500 RWHP to a stock 4.6 3V? For how long? Again, no expert but I would think you must have in excess of 12-15 pounds of boost and that is a lot for cast pistons and powdered rods"

 

9-10lbs of boost should get me to 500rwhp, you get more hp from pump gas on a Turbo then you can with a SC. all depends how one drives their car, thus the reason to upgrade to the Aluminator this winter

[68fastback]

too much plumbing and loss of Turbo efficency mounting them in the rear of the car like that. looks like a STS system. then again it depends on what goals are when doing a forced air induction system. my goal is to get 500+rhwp on the stock 4.6 3v. we're running a smaller Turbo that should spool up around 2500-2700rpm's. with a little luck it hits the dyno tomorrow. Dan, you going to like stage II of this project, 4.6 3v Aluminator with a possible compound boost system. what are you thoughts on the TVS vs the Ford racing Whipple? I'm running a ported TVS on a GT500 with over 700rwhp.

 

http://s221.photobucket.com/albums/dd174/a...nt=IMG_3780.jpg

 

Turbo driving a fixed-dsip S/C on an Aluminator build-up -- schweet!!! :happy feet: :bandance: ...damn, that should be very very cool!! Instant low-mid grunt and high-boost for a big top end!

 

The big Whipple should easily outflow the TVS but, in their respective sweet-spot range, I believe the TVS's overall efficiency is superior. Dunno comparo specifically to the Whipple but the TVS consumes considerably less HP at approx 650rwHP and same boost than the KB. That's HP that can not only go directly to the wheels but also that much less heat in the intake charge further buffer you from conditions where the tune would otherwise pull timing -- a double bene. From what I've read Whipple has traditinally been a bit more efficient than KB tho.

 

Also the 4-4 rotor design of the TVS should permit more boost/liter that asymetric (twin-screw) designs (5-3 and 6-4) that will become bearing-speed limited based on the speed of the smaller rotor before a symetric design like the TVS will. Twin screw manufacturers point out that it's not a real factor because you're way past the sweet spot at 16K rpm rotor speed (the TVS has 16K bearings) but that's sort of a self-damning logic. Possibly Whipple's new rotor design on the 2.9 will put it even further ahead of the KB but the small rotor still has to spin *much* faster. Admittedly there should be no problems and S/C bearings don't fail often. But if your're pushing things to the limit and feeding a S/C already-heated and -compressed air it might be more of a factor -- dunno.

 

I've heard a rumor that a bigger TVS may be in development but have not been able to get anything specific. 18 months ago they Eaton told me it' snot needed -- that the TVS is untouchable by any other up to 2.8L. Now they respond to the question. Maybe that means they're working one it, may be it means they don't. I think a 3.0 hi-helix TVS would kick butt up to at least 750rwHP or so (as the 2.3 does at 650-675rw), tho it could easily be spun further than that. I'm uncertain as to how pumping a S/C with a turbo affects the S/C's efficiency and the overall efficiency. I'd assume the most efficient design would remain so even when fed by a turbo but it's posible that port size becomes the dominant factor with a turbo out front -- dunno. Possibly for a 4.6 it's just not a factor flow-wise for a streetable ride.

 

We sure do live in fun times! ;-)

[68fastback]

Dan, actually it stated this turbo produces full boost at 3,000-3,500 rpm and makes more HP at 3,800-4,000 rpm than most SC. I am certainly no expert on turbos or SC.

 

500 RWHP to a stock 4.6 3V? For how long? Again, no expert but I would think you must have in excess of 12-15 pounds of boost and that is a lot for cast pistons and powdered rods.

 

Concur there is a lot of plumbing on the turbo and having an oil line from front to rear and back to front would concern me. But the title of the article certainly captured my attention! I am also curious how it would sound with the turbos so close to the exhaust.

 

Yeah, boost may be full-in by then but the dyno chart on that link shows torque peaking at 4250 or so. Boost actually reflects flow resistance not HP. For a given flow resistance more boost will make more HP, but less boost with less resistance can make the same or more HP and be faster and quicker. You want the most HP with the least boost because that is, by definition, more energy efficient. The problem with peaky torque is that it contributes for a briefer period of time as you sweep thru each gears. At lower rpm torque dominates and at higer rpm power dominates but [in ft-lbs and HP] they always cross at 5252 rpm because they are directly related. For a drag car, as long the curves produce a power band broad enough to cover the longest gear in the tranny, you can just keep it in that band through the gears. For a road course that's also true but it's nice to not have to shift at the g-limits in a curve or you'll lose it and that requires a broader power band. For a streeter it's really nice on the road to have a super-broad power so you have more energy instantly available to your right foot without downshifting and you can always grab more with a gear-change if you need it, but you'll need to grab it less often with a broad torque curve. While the dyno curve shows more of a peaky torque curve you'd expect from an NA engine that's not bad, it's just not as flexible in actual use as a fixed displacement S/C's broad torque curve. Certainly the curve they show from peak torque to peak power is plenty broad enough to cover any tranny spacing (even for a 3-speed automatic, I think) but not nearly as broad and fleible as a fixed-disp compressor can offer. That's why I was saying no doubt it will make good peak power with nice intake temps but why go thru all that plumbing when you can do a single up-front turbo or a street-friendly fie-disp S/C (or both ;-) as GT500-07 is doing)

 

(If I miss this thread a bit it's cause I'll be travelling, but I'll try to check it later this week at the latest -- I live vicariously thru you guys 'cause I don't have a stang right now <sigh> maybe eventually ;-)

[69dejavue]

Yeah, boost may be full-in by then but the dyno chart on that link shows torque peaking at 4250 or so. Boost actually reflects flow resistance not HP. For a given flow resistance more boost will make more HP, but less boost with less resistance can make the same or more HP and be faster and quicker. You want the most HP with the least boost because that is, by definition, more energy efficient. The problem with peaky torque is that it contributes for a briefer period of time as you sweep thru each gears. At lower rpm torque dominates and at higer rpm power dominates but [in ft-lbs and HP] they always cross at 5252 rpm because they are directly related. For a drag car, as long the curves produce a power band broad enough to cover the longest gear in the tranny, you can just keep it in that band through the gears. For a road course that's also true but it's nice to not have to shift at the g-limits in a curve or you'll lose it and that requires a broader power band. For a streeter it's really nice on the road to have a super-broad power so you have more energy instantly available to your right foot without downshifting and you can always grab more with a gear-change if you need it, but you'll need to grab it less often with a broad torque curve. While the dyno curve shows more of a peaky torque curve you'd expect from an NA engine that's not bad, it's just not as flexible in actual use as a fixed displacement S/C's broad torque curve. Certainly the curve they show from peak torque to peak power is plenty broad enough to cover any tranny spacing (even for a 3-speed automatic, I think) but not nearly as broad and fleible as a fixed-disp compressor can offer. That's why I was saying no doubt it will make good peak power with nice intake temps but why go thru all that plumbing when you can do a single up-front turbo or a street-friendly fie-disp S/C (or both ;-) as GT500-07 is doing)

 

(If I miss this thread a bit it's cause I'll be travelling, but I'll try to check it later this week at the latest -- I live vicariously thru you guys 'cause I don't have a stang right now <sigh> maybe eventually ;-)

 

Dan, your thougts on the centrifugal Paxton form SAI? As opposed to whipple and KB? Thank you 69

[68fastback]

Dan, your thougts on the centrifugal Paxton form SAI? As opposed to whipple and KB? Thank you 69

 

The Paxton is essentially a crank-driven turbo, but simpler install than a turbo -- depending on boost, it should have similar characteristics/curves but no exhaust turbine sizing/volume-matching issues and less plumbing since it's a crank-driven device independent of exhaust flow. I think the Paxton uses the Vortech V2 compressor now -- good product from what I've heard. It's a centrifugal (not a fixed displacement) S/C so will not have the low-mid punch of the Whipple, KB, TVS's broad and flat torque curve but is a nice simple way to get solid progressive power and prolly gentler on a non-forged motor since less low grunt. Curves should be similar to the STS turbo at similar boost levels but might come on a little earlier (3500 or so). Other similar choices are Vortech and Procharger. Rufdraft has the Vortech kit on his 4.6 (I recommended based on his goals and since the 4.6 isnot a forged engine) and makes 469rwHP with comp-3 cams (he already had them) and he loves it. Without the cams you should see 440-450, imo. He has a custom tune too. It's esentially the same as the SAI Paxton. SonOfGT has the SAI Paxton on his GT-SC and with a custom tune makes 480ish, if I recall. The older Vortechs required tapping the pan for lubrication but the procharger and current Vortech have built-in reservoirs, I believe, so no pan-tapping but maybe a bit more bearing heat and another fluid to change occasionally. Not sure if SAI's Paxton requires tapping -- likely they have switched to the new V2, but dunno. They're all very reliable and relatively straight-forward installs from what I understand, but don't 'light-up' on the 3V until 3500 or so whereas the fixed-disp S/Cs are already kicking you in the butt at least 1000 rpm earlier. The centrifugals and turbo will want gears to get boost up quicker after launch. The fixed-disps broad torque is more forgiving but will also benefit from gears. All depends on what you're looking for.