first off this is not my design i got it off one of the other srt websites. i've been looking around the web site and havent seen this on here yet and ive seen a few people on here have problems with ptb (part throttle boost) issues. trust me i did this and it works. basically what the deal is, when u put a mbc on your 4 you get ptb of like 10-12 psi (NOT GOOD !!!) REASON the computer is designed to only have 5-7 psi. and if you stay stock you lose the true potential of the car. well this set up will give you both you get the continous boost build of stock in first gear and in second thru fifth you run on the boost controller. TOOLS REQUIRED WIRE CUTTERS ZIP TIES 10 FT 7/32 VACCUM HOSE 1/4 IN DR SOCKET SET OPP. MANUAL BOOST CONTROLLER NAPA #701-1575 Hobbs adjustable pressure swicth $27.49 Chevy #1997152 Boost selenoid $21.86 IN LINE BLADE FUSE HOLDER W 3AMP FUSE MISC AMOUNTS OF 16 GAGE POWER AND GROUND WIRE (DEPENDS ON INSTALL) MISC RING TERMINALS But before you say "I can buy one just like it with a button to control high and low boost". Well, no you can't buy one like this. This design lets the factory computer control boost to an adjustable level(say 11 psi). Then, above that set boost level, the boost controller takes over. Everything happens automaticly with NO input needed from the driver. Why is this soo much better than a typical boost controller? Well, as we have all seen, our computers are VERY sensitive to too much part throttle boost. Just look at ANY dyno out there. The ones letting the computer control boost are getting torque REALLY coming on hard at only 2500 rpms while the ones with any kind of boost controller don't get good torque going till 3,000 rpms. Why is this? I'm going to go out on a limb here and say because of retarded timing even though I have no iron clad proof of it. This type of boost controller with also prevent compressor surge when using a boost controller. So, how does it work? Well, scottmech made a nice schematic of how everything is plumbed in and wired up so I'll post it. Now Scottmech used junk yard parts to build his. I used parts from NAPA and a Chevy dealership. Here are those 2 part numbers; I also used a 16 gauge piece of wire about 1 foot long that is fused with a 3 amp blade type fuse. The wire runs from the + side of the fuse box to the fuse holder to the boost selinoid + wire. Then the ground wire goes from the boost selinoid to the hobb switch and from the hobb switch to the ground i used the frame beam under front head light. the trick is you would have contious power because there is no on/off switch but there is no power because until the hobb switch activates it doesn't complete the circuit. Now here is how everything works. While cruising if you start to get on the gas just a bit the car responds just like it does when it is bone stock. The boost comes up to 5 psi and stays there! No 10-12 psi of boost at part throttle!! Amazingly, and I've talked to some other people that say the same thing, the car accelerates as quick, if not quicker at factory boost levels at part throttle then it does with 15 psi of boost when you have a boost controller connected!! Now, once you stab the gas, the boost rises like normal. However, once boost hits the boost level that the Hobbs switch is adjusted to, the boost controller takes over and your boost then raises to the level you have set it to. Now here are some cool advatages to this design. You can now have traction in 1st gear like stock(9-10 psi) and then when you shift to 2nd gear, your boost goes up to your level that the boost controller is set to!! Instant traction control! Not only that, but let's say that you got a bad tank of gas and your computer decides to retard timing and boost down to 5 psi. No problem. Since the computer has 100% control over the boost below the set level of the Hobbs switch(11 psi) then your boost controller will NEVER control the boost so you no longer have to worry about blowing your motor from a bad tank of gas!! the only trick is i did this to my car when it was bone stock except for a k&n cai and it worked great and if you happen to be going on a road trip you can pull the fuse and it will run at stock levels untill you put the fuse back in and it wont turn on the boost controller. when i went from the stock waste gate to the agp i pulled the fuse and then set the waste gate then i turned the mbc all the way down put the fuse back in and re-tune the boost controller and now i spike 20 psi and hold 15 psi to red line on the stock ecu and the reason i dont get overboost codes is because i pulled the red line off the intercooler and selinoid and capped both and remember to zip tie everything even were the boost gage attaches to break booster and under the dash cusion that way u get absolutely no boost leaks. THE BEST THING IS I DID IT FOR UNDER A HUNDRED BUCKS BEST BANG FOR BUCK INSTALL EVER well there it is hope this helps someone like it did me e-mail me replies to [email protected] I WILL ADD PICS OF MY INSTALL ASAP CAUSE I HIDE EVERY THING
Looks like something to try. Do you have any pictures of the install? Also, Will running a factory pcm with this set up still cause a "Check Engine Light" over 16 psi? It seems that a stage 1 pcm will be a good choice if you want to get the best performance. Just a thought. Let me know what you think. Thanks!
when i deleted the red line i never got another boost code on mine and my wifes car when we had stock PCMs. not sure if that would be the same for others.
