*cracking knuckles* Ok, I know I am going to get a LOT of replies to this one about how to do it, diagrams, etc... I'll have all of the info up on my website when I get time. Right now, I got a few deadlines to meet at work and Cobra work this weekend. I might get back to this post until next week. Just FYI...
Over a year ago, I attempted something never thought of on a blower setup on my Cobra. And the results were outstanding! Now I have a lot more detail on my website about this, but in short: I had a theroy that if you use a large blower (i.e. my D1SC) with a very small pulley that makes, say, 25psi at 7000psi, that's around 10 to 13psi at 3500rpms. And I was right.
Researching by-pass valves to finally finding two large units can control large amounts of boost, I went with the TurboNetics GodZilla valve. And vented it to atmosphere (there's a reason for that I'll get to later). Basically, I now had a blow-off valve like the turbos. :lol: But that wasn't my goal.
My goal: If I can build boost up fast (i.e. 12psi at 3500rpms), I should be able to bleed off the rest of the boost and substain 12psi from 3500rpms to redline.
After playing with a few different boost controllers, I found I had to go with an Electronic setup (EBC, Electronic Boost Controller). I went with the Blitz SBC-iD and got the matching Power Meter (BIG reason for that I'll get into in a minute).
I could not use a manual boost controller as it did it's job by bleeding off the boost. But it was proportional to the boost curve. So if I was bleeding off 50%, that was only 13psi at 7000rpms, but that also resulted in only 6psi at 3500rpms (remember, 50% of ANY boost level). That sucked.
I had to use the EBC to "use full boost" until a level/psi was reached. At that point, the EBC would bleed off the rest. The results turned out to be JUST LIKE A TURBO car. Good, full boost down low and held through redline.
Now the 2nd part is the Power Meter add-on. On high-HP turbo cars (Supras, Lexas, etc), there is a concept (most of us don't know this) called Stepping. Stepping means the 'cut off' or bleed off of boost happens at different boost levels, depending on speed. To accomplish this with the Blitz SBC-iD, I needed the power meter addon. The power meter add on did some other cool stuff, 1/8, 1/4, 5/8th times; HP rating, recording, etc.
In short, I configured the EBC to step in MAX psi levels as follows:
0-40: 8psi
41-70: 12psi
71-100: 16psi
101+: Max PSI (which hit 22psi a few times, in 95 degree weather)
Why did I do such a thing? Cause I had a front-mounted, LARGE, intercooler (see link in signature. :lol: ). And I ran about 18 degrees of timing. With 18 degrees of timing and 22psi, KNOCK/RATTLE at low speeds. But not with 8psi.
Hell, 8psi blew the tires off through 2nd anyhow, didn't need more.
But the cool thing was, the faster I went the more boost I could apply without knocking. This concept does NOT work with non-intercooled or air-to-water intercoolers (03 cobra, Vortech's aftercooler) for those that are thinking. Why? Well, you have the same amoutn of intercooling effect no matter what speed you go. So the Steeping method isn't an option. Humm, unless you use a boost-actived switch set at say 20psi and kick on the water flow at that level. 1) I have no idea who makes such a boost switch and 2) I can't say the cooling effect is immediate to match your boost step-up. Sawwy guys.
Btw, this was on the STOCK engine. Stock from the TB to the manifolds, to the cats (yes, OEM cats), to the stock 2.25" exhaust. Got 11,000 miles outta the combo until #7 ringland let loose. Planned on building the bottomend anyhow. Tune was good.
The coolest thing about the car, you know how your car feels in a 2nd gear sprint? How goooood anyone's car feels with power in 2nd? But once you shift to 3rd or 4th and still WOT, it's not there anymore (cause of gearing/speed)? heheh, I had the same pull in 2nd and 4th. People riding in my car quoted, "Your car pulls the same no matter if you are in 2nd, 3rd, or 4th!" Man, felt good too.
Now before you go off and by the Blitz to do the same thing, there's a special componant that is needed to accomplish this feat: a dual-port by-pass valve. From Vortech to ProCharger to Paxton, no one gives you a dual port, only a single port. Most high-boost by-pass valves for turbos (Blitz, TurboNetics, HKS, etc) are dual port.
You have a normal vacumm port that opens when the throttle plate is closed. But under boost, boost pressure appiled to this port keeps the valve closed with the spring pressure (my Godzilla had a 7psi spring preload, so it would stay closed up to 7psi no matter what). The "second port" is not used and is usually vented to atmosphere on turbo cars. Unless you are using a stepping system or have high boost (boost helps open the valve quicker). If you are using a stepping system, then you apply boost to BOTH sides of the diaphram and the 7psi spring pre-load keeps the valve closed, even though boost is pressent on the non-spring side
trying to open it. The spring's 7psi preload + full boost on the spring side of the diaphram keeps it closed.. The stepping system controls the boost level by opening the by-pass valve, bleeding off the boost, by restricting the boost amount being applied to the spring side port. So if you have full boost pressure being applied to the non-spring side of the diaphram, once the amount of boost exceeds the spring pre-load + restricted boost (say 5psi, that's 12psi total), it opens cause 12psi is present on the non-spring side. Simple theroy. Results are awesome.
Fyi, this is NOT a cheap endevor. The Blitz SBC-iD is in Summit for $670. The Blitz Power Meter is another $400 on top of that!
www.blitz-na.com But if you are serious, goto the Supraforums.com site and ask for a few vendors to quote them. I got both units for $700 from someone on there but instructions were in Japanese. Hehehe. Then there's the $350 for the dual-port by-pass valves. Ouch... Then the headache of figuring out how to fit something 10" long, 7" tall, and 4" wide in front of the engine before the intercooler on the tubing. *shakes head* I got pics of it if anyone wants.
Car overhaul almost done (suspension, tranny, engine). I'll let you know how the combo works out with a vehicle that can handle the power.
Eric
Ps, oh and the Blow Off scared off 100% of all ricers FYI.
Never got one rev, nor one race. Chickens.
