Forced Induction Dilema

[BAC5.2]

Supercharge or Turbocharge?

Supercharging obviously requires less piping, though it requries a bit more fabrication.

Turbocharging is more efficient.

Which option is the right option when the output goals are relatively mild?

I'd like to make 350whp and 400+lb-ft at the wheels with daily driving (25,000 miles annually) and low-end torque being the two major concerns. Reliability is EVERYTHING.

I'm leaning towards a whipple-charged setup, but I'm on the fence. Supercharging leaves little room for intercooling so that limits the amount of boost and thus power output. I could meth inject, but that's an additional cost (as well as a nusance down the road having to fit a tank and remember to fill it).

I'd think a whipple charged setup, 9.5:1 compression (forged pistons, forged rods, stock head), ARP head studs, and 12psi or so would do quite nicely.

With reliability, noise, and smoothness being extremely key, I'd like some help evaluating my options.

Transmission worries are easily cured. PPG 1-4 helical syncro set, PPG helical front and center diffs, with billet shift forks would handle that quite well.

I don't want a drag-racing queen, and I don't really care about embarassing Supra's on the highway. I just want enough power to keep it interesting, and I want to be able to pull like the dickens at low-ish RPM. Plus, I want the amount of weight in the car to not effect driving as much as it does now. I do occasionally like to get-down from a stop, but not that often. I just want a fun car, and truthfully the power goals listed above might even be overkill. I'd probably be happy with 300whp and 300ft-lbs.

What do you all think?

I also would like to avoid having to have a hood scoop or cutting for a front mount.

How much can I expect out of a blown H6 with forged pistons?

Thanks!

[SVXRide]

Given the nature of the SVX, I think that s/c should meet all your requirements with less "fuss" - 12-13 psi boost with stock internals and no body mods necessary. It will be interesting to see exactly what the upper limit is on the stock internals:eek: LAN has started cranking out his Stage 3 s/c kit and Phil and Chuck have turbos installed. I believe Phil has seen 8 psi with his turbo, while Young Tom has seen 12.6 psi with his Stage 3 s/c.
-Bill

p.s. I think 500 hp at the crank isn't out of the question....

[Beav]

No matter what you want now eventually you'll want more later - that's the beast within all of us. Better to start moderately and have somewhere to go when the 'more is better' bug bites.

[It's Just Eric]

Might wanna see what svxfiles has set up. He is running a centrifugal supercharger and has tested the gains and losses of numerous factors, including an intercooler, diffrent timing, injectors, ect. He is always willing to offer his hard earned advice

[Phast SVX]

Might wanna see what svxfiles has set up. He is running a centrifugal supercharger and has tested the gains and losses of numerous factors, including an intercooler, diffrent timing, injectors, ect. He is always willing to offer his hard earned advice

In all fairness the intercooler "loss" wasnt that. The whole idea behind an intercooler is to increase density, on a turbocharged setup and a manual boost controller you will have a pressure drop with almost any intercooler, and will be forced to turn up the boost to compensate. On a turbo system running off the gate(Weather it be internal or external) the pressure is what defines the boost directly.

Even with less boost you are running a drastically higher density ratio at the same or lowe pressure ratio. In that case less boost will mean more power. The blower being a static boost pressure will see a slightly lower boost pressure since its driven off the motor and not a gate.

[svxfiles]

In all fairness the intercooler "loss" wasnt that. The whole idea behind an intercooler is to increase density, on a turbocharged setup and a manual boost controller you will have a pressure drop with almost any intercooler, and will be forced to turn up the boost to compensate.
Even with less boost you are running a drastically higher density ratio at the same or lowe pressure ratio. In that case less boost will mean more power.
Thanks Eric.:)
Phast, what you say is true, in reguard to hot air turbochargers.
But on my setup, he intercooler was just a restriction, causing a loss of power.
Since I have never seen my intake manifold over 140f, even on a 100f day, it was not necessary for me.:)
If you flow enough air, boost pressure is only an indication of restriction.;)











Flame suit on.:rolleyes:

[TomsSVX]

Tom not necessarily. You may be seeing manifold temps at 140* but that not saying the air commin from your relatively warm blower is at that same temp... an intercooler will do nothing but help. Believe me, if your intercooler was on and you could run 8psi, you would be making a TON of power.

Tom

[svxfiles]

Tom, when I measured my charge tube, after the SC and before the maf and manifold, it was much cooler than 140f.:)
I'll check it out again when the new SC gets here.
Aint science FUN!:D


And yes Tom, ice cold air would be a hoot!
At 8, 10, or 12!!!:) :)

[TomsSVX]

good luck buddy!!!:D Hey, when I see you next I can show you clean hands:D :D :D :D

Tom

[cdigerlando]

Boost and intercoolling are a little tricky. The more backpressure you have, the more boost that is needed to overcome the additional backpressure making the air to the intercooler hotter. I have heard figures of about 8 psi being the break even point, but I'm sure it depends greatly on the efficiency of the turbo, the backpressure and efficiency of the intercooler etc.

S/C or Turbo? Good question. I don't think its been answered yet on the turbo end. On the S/C end, you might consider LANs kit. Unless you want to DIY. Personally I wouldn't go through modifying another SVX. Too time consuming. I do love the car though.

[mikecg]

What ever you do, enginemanagement is an much need thing to look at. That is were LANs system is so good. It provides not only everything to install the S/C, but also larger fuel injectors, a better MAF for metering the air and the fuel and timing maps to run it all.

As for S/C verses turbo, what your asking for with the lowend torque and power, a roots or twinscrew S/C system is your best bet. In order to get the lowend your looking at you would need to run a small turbo, which would not do much in the upper reaches. LANs system uses a whipple twinscrew supercharger which makes boost off the line with no lag and simply pumps more are to hold the boost pressure as RPMs increase. Even a Vortec style supercharger doesnt do alot for you at lower RPMs, because the compress has to be turning at a certain RPM before it can start to build pressure.

I've always looked at it this way. If you want big numbers at the peak, use a big turbo or Vortec S/C. If you want a nice wide powerband with a smooth delievery you want a roots or twinscrew. The Roots are cheaper, but less effiecent and cant boost as high as a twinscrew. Much of what I'm saying can be found in the ECUTune Stage III development thread. I have a stage III on my SVX. I've also owned a 91 Eclipes turbo and currently am playing with a Conquest TSi. My SVX with the StageIII twinscrew system is much tammer than my stock Eclipse was. And the SVX has nearly twice the power.

[cdigerlando]

[QUOTE=mikecg]What ever you do, enginemanagement is an much need thing to look at. That is were LANs system is so good. It provides not only everything to install the S/C, but also larger fuel injectors, a better MAF for metering the air and the fuel and timing maps to run it all.QUOTE]

I will second all of this. This is all very important.

[BAC5.2]

I'm not necessarily going to use the engine in an SVX, I'm just throwing around ideas at this point.

I know the mod-bug and I know the desire for more-more-more. My other car is a 94 Legacy Turbo (with a front mount, big turbo, suspension mods, and a dogbox). It gets down enough that I don't need another ridiculous car. I'm selling the Legacy, but I have no lack of opportunity to drive cars faster than I'll ever be. Plus, this is my daily driver, so reliability is #1 priority.

Engine management is important, and I'm toying with how to approach it. It's one of my least concerns about the project. Being emissions compliant is important, and I want the ability to tune the car myself.

Sounds like a supercharger is going to be the winner for my application.

I'm concerned about intake temperatures though, and I would feel much more comfortable if LAN's stage 3 setup had some form of charge cooler (Eaton's sandwich AWIC seems like a really good idea for example).

I'll have to give LAN a call and see what they think...

[SVXRide]

Phil,
not to highjack this thread too much, but I'm going to be up at Altered Atm. this coming Monday afternoon. Are you going to be at your shop (Andrewtech, right?)
-Bill

[BAC5.2]

Monday the 2nd?

I might be at Altered watching a car we built get tuned by Phil from Element Tuning (2.8L, GT35R STI)

Either way, I'll be at the shop or at the dyno watching. I won't be around from 10:30 until 1:00pm.