Gretch

I am happy to give you my opinion, in detail, in a PM.

In summary, however, I am VERY pleased with my install, the quality of the engineering that went into system design and component building, the ease of the install, the completeness of the instruction manual, and the kit itself, the readily available customer support I received, the integrity and user friendliness of the vendor, the continuing interest of the vendor, the updates and upgrades provided by the vendor and, for the minor issues and questions I had over the last year, the prompt and courteous resolution of such. And "yes, I would hire him again".......

goliver, why not let me know specifically what your questions are. I will answer all of them, or send you to people who can. You also might ask several other customers of the various solutions here. I would do it in private as you will not get a complete, unvarnished assessment if people are required to do so in public.

Jim_H

Dave,

My GT with around 310HP dynoed at 462 (7#'s) after supercharging. Are you saying that's not possible? Why? Maybe we could start a non abrasive thread about this.

James-man

quite right.

Perhaps. Excusing behavior by labeling it as a personality trait is a slippery slope. Children with ADD still have to try to follow the rules and are still subject to consequences. There seems to have been a pretty clear charter violation with the behavior. Enough people were bothered and the rulebook was opened. On the leniency question of other guilty parties, I dunno - why do some people get speeding tickets while others are let off with a warning. We are looking at no more than a minor injustice here. I suppose that Randy can ban Andy for a day just to be fair about it.

Randy's comment was somewhat surprising, but maybe I can write that off as a personality trait.

Most people will welcome him back when he is done with his time-out. Will he come back?

goliver

Thanks Gretch.

m21sniper

GRETCH: "I have observed your reaction to a bit of tweaking here on this board, you came close to a banning yourself I believe."

I very highly doubt that.

The only one i had it out with was Normy, and well, he did go out of his way to instigate me on several threads. We seem to have since made peace.

I am not a mod here, so i can act much differently than i do on my own site where i'm the admin. Here i'm just one of the clowns.

And what's with all the free speech quotes by everyone?

There is no free speech on privately held internet forums such as rennlist.

PS: As far as lag i like him fine, and i do allow quite a lot of bickering back and forth at my site, but each mod has his own definition of acceptable behaviour, and it's up to him to enforce the rules as he sees fit.

That's all Randy did.

Tony

Im currently on vacation and unfortunately get myself near a computer now and then.
Now i see all this crap. The banning IMHO is uncalled for and a childish statement like that backs up what i feel.




Also...
Personally i like everyone involved but when the $hit hits the fan i wont let people post things like this on a pass word protected forum and out of the other cheek talk about "libel" or what ever.
Ban me here if you like Randy...Ban me there if you like Andy. I really dont give a hoot. Iv thoroughly enjoyed the last 2 weeks away from the comptuer doing 400 miles on my bicycle instead...looking forward to many more.

fromt the 928Supermodel forums.

jorj7

Dave,

I can see how a 300 rwhp car can get 450 rwhp with 7.5 psi boost.
Remember the intake manfold is replaced, the injectors are replaced,
the fuel pressure regulator is replaced, and an intercooler is added to
cool the air, so it's not just a increase in air pressure. Also, many
of these cars have exhaust mods that can support 5-600 rwhp. The
mods were put on a 260-300 rwhp engine, and probably gave some
marginal increase in hp, but no where near their potential. When the
s/c was added, the exhasut could now allow the system to breath like
it's suppose to. The net results is that the car will produce more power
then just that attributed to the boost numbers. This is a complicated
power system we are talking about and we've not changing just one
variable.

James-man

I thought all boost was magic!

I am not very knowledgable on this stuff but I recognice that a variable in the rules may actually changed for the screw set up: Intake restrictions. The entire intake plenum is absent on this installation and total length of intake tubing is reduced. How much of a difference does this make? I am sure that people can thumbnail estimates but to quantify with all of the math and equations without supporting empirical data makes this an unresolvable debate.

What else is absent from the math? Swiching to electric fans? Accidentally bumping a fuel injector and possibly loosening a clog that was present in the baseline? Or is there magic at hand?

Was the dyno reading incorrectly? Even if not, it make one wonder what must be done to ensure the dyno itself is a constant. Dyno a bunch of other unmodified cars on the before and after to prove readings?

In the end, since nobody is selling twinscrew kits anymore, I am not sure that debates are even relevant. Let a guy that has a piece of paper that has the number 450 on it say that he has 450.

Absolutely, we should let a person complain when they paid money to get X additional HP and only got Y.

Good lord. I talk too much about nothing. Sorry.

James-man

--- Accidentally bumping a fuel injector and possibly loosening a clog that was present in the baseline? ---- Er, Um, Replacing

George's list is better than mine.

m21sniper

In a perfect system with no compressor induced intake air heating, no inlet system pressure drop, and no compressor induced drag, one bar of actual boost(14.7psi) is the equivelant to doubling effective displacement, which in turn doubles horsepower.

Example: A 300hp engine that operates at 100% volumetric efficiency, and that's producing a true 14.7 psi of boost with an electric supercharger(which produces no drag on the engine at all vs the massive power consumption of a belt driven SC at high rpms) and that maintains ambient air temp straight into the cylinders will produce exactly 600 horsepower.

At .5 bar(7.35psi) the same engine with the same 'perfect' inlet and SC system will produce 450hp.

Of course no engine is perfect wrt VE, no belt driven SC operates without drag on the engine(nor even comes remotely close, hence the inherent superiority of turbochargers), and short of nitrous, there is no way to maintain ambient air temp of the AF mixture all the way into the cylinders regardless of how big your Intercooler is.

All of that comes right out of the Corky Bell book "Theories of Turbocharging".

Hence the skepticism by so many people about the seemingly impossible power increases.

Ketchmi

It's simple math, the amount of air/fuel to produce 300rwhp multiplied by 1.5 (a perfect world) will give you 450rwhp. It's not a perfect world. If you aftercool the supercharger, you may not have the loss due to temperature but you will have to produce more boost, there is a loss of boost through the intercooler core that must be made up by driving the supercharger faster which requires more hp to drive (loss). I have seen about 1.5 psi loss through the intercooler. So at this point, you are making 9psi boost to get 7.5 psi of cool air to the manifold, can you really claim that you made that power on 7.5psi?

All the required mods, ie injectors, regulator, etc are necessary to maintain the proper air/fuel ratio and do not increase the power themselves. They are a requirement for the increased level of proper air/fuel mixture needed by the supercharger.

m21sniper

"I can see how a 300 rwhp car can get 450 rwhp with 7.5 psi boost.
Remember the intake manfold is replaced, the injectors are replaced, the fuel pressure regulator is replaced, and an intercooler is added to cool the air, so it's not just a increase in air pressure."

On that list the only thing that's really an additional power builder beyond what the system actually needs to maintain a proper AFR is the intake manifold and the intercooler. But the intercooler is only attempting to recoup power that's lost via charge air heating, and no intercooler is 100% efficient(or at least not for very long once the engine compartment reaches operating temp). Changing the intake manifold can cause a pretty significant power gain in and of itself, and is really the one thing one could point to as why the system seems to make 'impossible' gains.
I have little doubt the power numbers listed are accurate though, a lot of people have backed the claims up with actual dyno runs. Even if they're off by +/- 5% it's obvious the roots style blower makes more than power one would expect.

IOW, it appears to work better than one should reasonably expect from any SC system.

That's a real tribute to Andy's system IMO.

Another possibility is that the Porsche V-8 does not possesss particuarly good Volumetric Efficiency, and therefore there is a very significant power gain before one even begins to make positive boost.

An 85% VE would equate to a 15% power gain even if the blower system only drove the system to a true 0 boost(100%VE) condition without adding any charge air heating.
IOW, a 300hp engine operating at 85% VE would produce 345 hp at a true 0 boost reading if all other conditions remained constant. That's the whole rationale behind Tunnel Ram intake manifolds.

I doubt the 928 engines VE is that low though. It's probably about 90%(and probably even more for the 4v motors), but that would still result in a 10% power increase at a true zero boost rating minus air inlet heating.

Randy V

Much easier to launch against the guy who's here every day, isn't it lads.

Yes, I am partial - partial to civil and intelligent discourse. Paul possesed the latter, but not the former.

It seems a bit naive to think that Tim was unaware of Paul's missives here. Tim could have asked Paul at any time to cool it.

When Paul returns, I hope he will contribute within a spirit of sharing and cooperation.

I hope Tim can do the same. It would be nice to see him drop by here other than during instances of high drama.

James-man

Dave & Sniper, the 300 HP baseline is from an imperfect world. If it had perfect world conditions, the baseline HP would be higher, wouldn't it?

Gretch

Must be good to be king..........