blown 87

All i want to add is that i have a centrifugal on one of my cars (Corvette)now with a air to air intercooler, my next boost project will be a intercooled twin screw.

The centrifugals make great power up high, but after driving some of the twin screw cars (Mustangs and Corvettes) that made my mind up .

There is just more power when you want it for the kind of driving i do.

Cameron

Yeah, the gap is not as great if you adjust 50-75 hp for runner length. Still a gap in the low-mid rpm range of about 75hp in this study after adjustment, if I read it right.

Larry928GTS

There are three cars just on this board running over 6psi without an intercooler that I can think of just off the top of my head right now. You could probably start by asking Tim Murphy how many stage one kits he's sold if you really feel the need to get a complete count of all of the people who are sucessfully running more than 6psi non-intercooled. How many of the FAST kits were sold and installed without intercoolers? Call Vortech and ask them how many non-intercooled kits they've sold. Bill Ball has what's regarded by every source I've seen as the least efficient type of the three main kinds of supercharger on his car, and he's running 5psi without an intercooler with that. He's been doing it for some time now, and has even done offroad racing with it in warm weather.

pmotts

Least efficient? By what source?
These cars don't do well in off road racing...

Larry928GTS

Every single magazine, web page, book, and individual that I've seen comment on it in the last 30+ years. Do you have even one single source that claims the roots type supercharger, which is what Bill Ball has on his car, is not the least efficient of the main types of forced induction?

Why did they limit the boost in that magazine article? Why didn't they allow each system to run as much boost as it could without detonation? I guess they must have just forgotten or not thought about measuring the engine air intake temperatures and comparing those too.

You mean where Vortech, who sells intercoolers for some of their systems, tells you that you generally don't need one for street purposes and 8-9psi of boost?

hacker-pschorr

Wouldn't it be more fun if all the SC guys gang up on the Turbo guys?

Bottom line is - I love my setup, I love how it looks, how simple it is and how clean the package ended up. I also like the security of a system that can go back to stock in less than 10 minutes (well, close enough to drive) in case anything goes wrong, or if you need to remove the boost for any diagnostic work. Same might be true for the other setups, I'm not sure what would happen if you tried to run a twin screw or eaton car with the belt off.

pmotts

I forgot Bill was running the roots, my bad.

pmotts

The TS is kind of doggy with no belt and yes, I know this from experience.
(edit) I should say real doggy.

hacker-pschorr

Cook, I always wondered that.

I had an issue non-boost related after installing my system. I had to pull the hose between the blower / intake a few times to test the system without any pressure. So I was still turning the blower, without generating any boost there isn't much resistance there.

Abby Normal

All 3 or 4 of us? Bring it ..

Bill Ball

Yes, my modest 5 PSI Eaton (roots) has presented no driveability problems since installed in March 2005, 17k miles ago, after I got some initial manifold leaks sealed (and that only affected idle smoothness). It's OPEN road racing - high speed stuff on the pavement in the desert heat. No problems at all with the SC crusing at 150-170 in 90-95F heat at 5-6000 feet.

Certainly roots is regarded as inefficient, but Seth got over 400HP with an IC and 6 lbs on his 89 GT, so they can produce. For me it was a cost thing. Andy announced a kit available with a mildly used Eaton for $3200 and I hit the Buy button. And to your point, I did want to establish whether a modest 5 PSI Eaton kit was safe in desert driving running pump gas and stock fuel control, and I think it is. However, I do plan to install an IC this fall.

hacker-pschorr

Just an FYI - friend of mine has spent the better part of 7 years building a business where 75% of what he does is re-tuning cars on the dyno. He specializes in Corvette's. Last dyno tune day (averaging 20rwhp just by computer tweaking on ZO6’s) he commented on superchargers. He said he would never buy a twin screw or Eaton blower for a C4 or C5 Corvette. He said all things considered – reliability, tuning, overall power etc… he has yet to find or has been able to get a twin screw or Eaton setup to work as well as a Vortech supercharged system.

He also mentioned his last visit to a very well known Corvette tuner’s factory how many engines were on the scrap heap during testing of these setups.

Don’t shoot the messenger here, just relaying since his knowledge of Corvette’s far exceeds anyone I know, and I’ve been heavily involved with Corvette’s long before I even knew what 928’s were. Seeing what he can do to a stock Corvette with a laptop makes me very jealous.


EDIT - this is not to be taken in any way shape or form as a rip on any eaton or roots setup on a 928. They are different cars - just relaying what a known Corvette expert had to say about the subject on Corvette's. If I said his name, I'm sure a few here would know who he is.

Bill Ball

No problem, Hacker. I do think Vortech is simpler to implement since there are no manifold development issues. No MAF and throttle relocation as well.

hacker-pschorr

Lets just say I took along some dyno sheets that day as evidence of what 928's could do. I was the only Porsche guy in this group – at least 20 people there.

The discussion started when I was talking about the Vortech setup going on my car – and a few guys started snickering, saying I didn’t know what I was talking about since the only way to go boosted was a twin screw. This guy jumped in and shared why they were incorrect – in relation to their cars. Needless to say, when I was done explaining some of the motors in design / testing around the 928 world, it was obvious which motor had the better overall design. The bottom end / valve train of a Corvette (pre C6, this was 2 years ago) has nothing on the 928 engine in terms of strength based on this conversation. He was telling stories of motors on the dyno grenadeing the bottom end in testing on the engine dyno under boost. I have yet to hear about any 928 – even Todd’s 25psi monster - having lower end issues.

I really had fun showing them the web site of a big block Chevy Bonneville car with a S4 32 head installed. That was a fun day – I did not make many new friends.

There is no question the Vortech is the easiest, simplistic setup out there for any car. I think the early twin screw guys are lucky these engines are as strong as they are. DR is / has gotten the bugs worked out, it takes time. Tim didn’t shoot out of the hole on day one with a 100% perfect kit. This is 4+ years in the making he’s poured into this project. 32+ kits later – the results are obvious.

We worry about timing belts, my friends modified C4 lost a timing chain last year – not many miles on it either. Well, not the entire chain, teeth off his timing gears were found in the oil. Thank goodness he caught it early – day before a DE weekend.

blown 87

A lot of guys just LOVE there Vortech with no IC on meth, i almost went that way and in retrospect i wish i had of run a meth system instead of a IC.

Something like the blowerworks setup from Greg Carroll.

One thing that i do really like about the fixed displacment superchargers is the low RPM boost.

One other thing is that you had almost better be prepaired to lose a engine if you run close to the edge of detonation, all it takes is a little bad gas or just a little lean to make a lot of junk parts

Thanks for the heads up, we are thinking of doing a blower on a C5 and he wanted a twin screw, i will show him this.