IcemanG17

There are several boost options out there...... two supercharger types (twin screw or vortech).....then the single mid mount turbo (robinson) and the upcoming twin turbo (kuhn).....currently the system with the highest dyno #'s is the twin turbo...with 565whp 548 torque on a stock internal engine...... a similar boost vortech kit put down 511whp....... the twin screw is set at lower boost so its dyno #'s are slightly lower than the higher boosts kits......

it all depends on what you want to do......500+ whp should get you above 200mph with the 2.20 rear end pretty easy...... in theory the 565whp turbo could do 215+mph..... but the 603hp custom vortech in green bay could do even more.....220+??

But 500whp will be VERY hard to control with street tires or near stock width.......race 928's with slicks can spin tires with ease with this kind of power....... Louies monster puts down 584whp & is a wheelspin machine with the 2.72 gears.......

Jim R.

Definitely do a search, there is much out there.

I've had my Murf setup for a few years now and love it. As far as power, I will re-dyno mine in the spring, but I put down 540 SAE corrected (not standard dynojet corrected!) RWHP on a superflow (reads 10% lower than dynojet) shutting down at 5800 RPM's due to quickly decreasing fuel pressure at 11 psi of boost. New fuel pumps have fixed that. It is easy to drive around around town with my wife and kids in the car, and just plain wicked when you hit the loud pedal.

On a road trip, I still got 20 MPG at a 75-85 mph clip with a few trips well into the mid triple digits. Still passes NY emissions even with aftermarket cats. And fast enough to scare the crap out of anyone who has asked "how fast is it ?".

There are options for stage 1, 2, 3 setups, and you can upgrade at any time.

There are other options for boost. There is only one that is proven on dozens of cars, is available right now, proven, documented, and guaranteed performance gains, and has second to none support by Tim and crew.

And yes 500+rwhp is fun to manage on 295/30/18 street tires!


Jim

Courtshark

I'm sure I'd eat up tires on an annual, if not faster, basis with boost. I'm running Goodyear's off-brand, Fierce, in a 285-35-18 right now and they're holding up great. Not bad for $270 for the pair. But with boost...

Another problem for me... no LSD... yet! Anyone here boosted a non-LSD car?

RyanPerrella

I thought the Murf was stuck at 400-450 max RWHP. Now his setups are topping 500? I need to do some research, I guess you guys have made some serious improvements in the past year.

Keep it up!

RyanPerrella

I just looked at the Murf site but its just one page. Can someone point me to where i can get numbers, HP and cost and take a look at the different options for the kit.

Where can i see this information?

IcemanG17

Ryan
Most of the gains came from sharktuning to get optimum performance..... Tim posted a thread about his stage 3 kit...its all in there....

He did say that there is room for more.....11-12 psi on street gas with virtually no knocks.....so he could bump the boost a touch or tweak igniton for a touch more power...maybe 550whp with ease......Jims supershark has to be close to 600whp now..... thats over 700 crank hp.....plenty in anyones book!

largecar379

Matt--

I would advise skipping the water/intercooler idea.....air to air is more efficient and will keep the air charge cooler.

Diesel trucks went that way (air to air) years ago......

--Russ

ShawnSmith

murphs kits are listed at 928motorsports, showing stage 1, 2, and 3 along with details, prices and dyno charts.

Z

The official Murf test vehicle is "the wife's car", which is a stock '87 S4 with an automatic transmission.

With the stage-1 kit it made 407rwhp SAE corrected.
With the stage-2 kit it made 442rwhp SAE corrected.
With the stage-3 kit it made 510rwhp SAE corrected.

Boost was increased over what it was for the stage-3 kit results above, but winter arrived before there was a chance to get it to the dyno for new numbers.

I'm not sure if Tim is really offering the stage-2 at this point anymore. The stage-3 is only a little more money than the stage-2, and is well worth going to instead. Not only does the stage-3 provide more horsepower, but it's also just a better way to do things as far as the tuning goes. The stage-2 method definitely works, but the stage-3 is the way that the factory would do it.

If he would have been on a DynoJet instead of the DynoCom dyno that was used, the results should be around that 600rwhp mark, according to the dyno conversion factors that the dyno manufacturers use. Using the STD correction factor that some people use, instead of the SAE correction that was used, would make it higher too.

FlyingDog

John and I have discussed the various reasons for each. Air/air is the better solution for most systems. As I said, my ideas on turbocharging a 928 are more extreme. Running air/air on my ideas would just be too much piping and not enough cooling.

Bill51sdr

Ever heard of Ball Ball?

shaaark89

ok,
so i have a murph stage 3+ s4, 928 specialists twin screw gt, 6.0 liter supercharged stroker, and 6.4 liter stroker with louie's 8 throttle body intake.
i wish i knew which one was best.....
if i had to philosophise, i would say put a twin screw on the 2.2 rear end auto, a stage 3+ on the s4 5 speed, a stroker on the gt, and a supercharged stroker just for fun.
haven't played with the turbos yet (unless you count the audi)
happy new year!!!!

FlyingDog

Now you're just rubbing it in...

hacker-pschorr

Do a quick test, heat up a piece of metal to 300 degrees. Dip one in 50 degree water, spray the other with 50 degree air.

Guess which one will cool down quicker?

How about another test that is a lot more fun. Wearing only a pair of shorts, walk into a freezer that is set to 32 degrees. Now jump into a lake with a water temp of 32 degrees. I've done both and I can tell you which one cools you down the fastest.

The fastest, most powerful car ever produced (Bugatti Veyron) uses air / water intercoolers. I would rather lean towards the technology used in a supercar versus a Kenworth. Also worth mentioning is the new 600+hp Corvette ZR1 uses an air / water intercooler......and the McLaren SLR.



Each system has it’s own advantages and disadvantages, just like turbo’s vs. superchargers vs. strokers etc…. There is no “best” solution, there never will be.

Most of us choose air / water for many reasons. The #1 in my book is simplicity. Running a water line is a hell of a lot easier than trying to route the necessary plumbing for an air / air setup. Not to mention I have yet to see an air / air on a 928 that does not require cutting holes into the car. To some this is not a big deal, it is to me (at least on my street car).

People talk about heat soaking as a negative to air / water. I have been monitoring the water temp in my setup for a while now.
Has never been an issue, even on the dyno when we held the car under load / boost for a longer period of time than you could ever reach on the street – water temp was still fine (close to ambient).
Cruising around town in traffic I have constant, ambient temperature flowing through my intercooler.

For the track I’m looking into an air / air setup for my 79. Why? One less fluid to keep an eye on.
This does open up another problem – overheating. Too large of an IC in front of the radiator can / might block enough air going to the radiator to cause an overheating issue. A fellow 928 owner with a track car has this problem with only 6psi of boost.
Smaller IC’s on the side might get in the way with the brake cooing ducts. So like everything there is a compromise.

To say pick one over the other due to efficiency is not 100% accurate. Install too small of an intercooler on any car the effect will not be much different than not having an IC at all. However, it is much easier to install a larger air to water setup than it is to install a larger air to air system.

James-man

Not to nit-pick but this is wrong. You must first wrap yourself in aluminum or tin foil, plus you can't jump into an entire lake - that is way out of proportion, you only have about a couple buckets of water to jump into.

You are justified in desiring the mystique of a supercar, but doesn't a supercharged 928 qualify as a supercar regardless of whether it is air or water intercooled?


Tinfoil wrapped in the freezer will stay warmer longer than in a bucket of freezing water. Either way, Brrrr.

Point of all this being there is no direct air to air or direct air to water transfer. There is metal somewhere between. Heat transfer properties of the metal come to play and ultimately you are looking at metal to air. So in general, does the metal really get cooler with water that warms above ambient temperatures versus ambient airflow?

Not a scientist here, but it would seem the analogies/examples are not 100% transferrable.