wastegate + centri =

Discussion in 'Forced Induction & Tuning' started by tooslow, Jul 30, 2007.

  1. tooslow

    tooslow Active Member

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    Ok guys, i have something i need to ask about or just discuss with who ever is interested.

    i've recently seen a set-up done that i don't see often and i'm wondering why not. Its a simple concept. the set-up was just like any other centri blower set-up, only just before the FMIC was a massize Tial waste-gate that regulated boost. The centri unit was equipped with a much smaller pully than normal. If i'm rememberring correctly, it was a F1 blower with a pully that normally would produce around 30psi at redline. Only the engine never seen anywhere neer 30psi, the wastegate would cut it off at 15psi. or what ever boost level he would set the waste gate too. The extra air was plummed back into the intake pipe for the S/C as to not screw up the draw through MAF set-up.

    why doesn't every one do this?

    with the extremely small pully and wastegate, the supercharger builds more boost in the lower rpm's than it would at the same psi on the larger pully. 15psi was reached on that F1 blower set-up somewhere around 3k rpm, if not just before.

    i'm still looking for other cars with the same idea, so i can learn if there are any drawbacks or anything to be overly worried about by doing this. so far, i don't see any. as long as the wastegate is properly sized to handle the extra airflow, there shouldn't be much other worries.

    if i'm thinking this out thoroughly enough, it seems that a set-up like this could actually be more benificial than a twin screw or even turbo. By sizing the pully to get the most effective spool time for your set-up you can use a much lower gearing much like on T/S and turbo aplications. only this way, you are in control of the powerband. too much low end? go with a larger pully. less spull, no tire spin. too laggy, smaller pully. boost is being regulated by the wastegate, not the pully. that would also make upping the boost work just like on a turbo. you could have multiple tunes. for example, 10 psi to cruise around with and 15psi for some fun. maybe even 20+ with race fuel. without ever changing the pully. (as long as the wastegate is up to par with the boost levels)

    i'm thinking about maybe doing this once i start building for power. i like to researcg any and everything i can to make cars faster, so since i've bought this car (and even before) all i do is research and read. everything from 5.4l swaps, to fully built blown set-ups.

    I really like this idea, and its something i can do within a timely manner because it isn't as far stretched as my normal "ideas"

    I think if I do the usual bolt-ons and supporting mods that our cars need before being boosted i can do a donsized version of that set-up. I still have a stock nPI, so maybe some steen heads or just the stockers and blower cams with a procharger d-1sc. It would be a 350-400rwhp car much like the many on this site, but i think i can do this and have a car that is much faster than normal for its power. extra small pully and a wastegate set for 9-10ish psi with just small enough pully to spool just fast enough not to kill the rear tires. maybe even stay on the 3.28:1 or 3.55:1 gears. gearing is a way to take advantage of a given powerband, but if you can control the powerband the gears themselves shouldn't pose that big of an issue.

    what do you guys think? do i need to be slapped?
     
  2. tooslow

    tooslow Active Member

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    sorry, my "w" key is a bit screwed up, so if i don't jam it down it doesn't work.
     
  3. quickstang_1994

    quickstang_1994 Well-Known Member

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    the small pulley equals belt slippage. I read the article in MM&FF and it calls for a seperate fuel source(computer) or I may have been reading it wrong. First put on the blower then modify were you wont do it twice. I thought of doing this but when I start hitting good boost the car is hard to handle.
     
  4. tooslow

    tooslow Active Member

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    thats why i'm think of not going super small on the pully, and of causre i'd have the most ribbed pully i can get with the kit. procharger has a 10 or 12 ribbed pully right? also, having trouble keeping the car under control would be why sticking to a conservitive gear would be huge.
     
  5. Paul

    Paul Legend

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    I had thought about doing this before that article came out in MM&FF, but decided not to since I don't have an intercooler yet, and the incoming air charge would be a bit much.

    If you have a good progressive boost controller, and a way to electronically change the wastegate settings, it wouldn't be that hard at all. I was going to set it up through my AEM. The AEM has a progressive boost controller built into it, so you can simply wire it up to a GM boost solenoid attached to the wastegate, and regulate how much boost you want at a given RPM, and ultimately what your maximum boost would be.

    Only considerations would be:
    1. Ensure you have a good wastegate suited for the air volume you are pushing
    2. Ensure you can regulate air charge temps (via intercooler) to an appropriate temperature
    3. Ensure you have a decent belt tensioner to help reduce belt slippage (or use 10-rib, for example)
    4. Ensure you have a GOOD standalone setup that can do what you need it to do (like a FAST XFI, or maybe an AEM) in order to control your boost settings, fuel requirements, and so on...

    Oh, and screw MAF. Any good standalone has speed density with MAP instead of MAF. I hate those goddamn things.

    Paul.
     
  6. tooslow

    tooslow Active Member

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    a SD stand alone would be ideal, but by recirculating it and staying MAF would have been a simpler yet not as effective way to control the engine.

    i believe MM&FF used a FAST XFI system.

    no chance of upgrading the stock MAF system and tuning with SCT software?

    i think i'f i have to go stand alone i'll be like you guys and seek out something else.
     
  7. Paul

    Paul Legend

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    You would still need to buy a boost controller so you could manage the wastegate.

    Just FYI - all of this would NOT be an inexpensive proposition.

    Paul.
     
  8. tooslow

    tooslow Active Member

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    I know a boost controller would be required, and it is not a "cheap" idea. but it would be cheaper than a turbo or twin screw. i'm not out for the baddest car out there, just something fun that gets the job done. I would like only to get what the stock block is capible of safely. around 350- just under 400rwhp. this seems like a very good way to make the most out of that limitation. Peak hp is only one aspect of an engine or car. I want to stretch that as far down the powerband as i can.

    i really wouldn't be using more than one boost level, so multiple tunes and complex settings shouldn't be a requirement.
     
  9. Paul

    Paul Legend

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    I doubt it would be cheaper than a turbo or a twin screw. If what you're wanting is 350-400 rwhp, just do a normal HCI non-intercooled blower setup and you'll be there with no problems. The standalone alone will cost you $2K, or the price of the standalone boost controller, wastegate, piping, FMIC, and everything else will be thousands more.

    A setup like you're describing is for people that want MONSTER power on demand (I mean in excess of 700+ rwhp) but want to keep it down on the street. It is way overkill for what you want to do.

    Paul.
     
  10. tooslow

    tooslow Active Member

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    theres no such thing as overkill. haha

    yeah, i hear what your saying.

    if i go s/c, it WILL be intercooled. most likey a d-1sc. i know a p-1sc or vortech s-trim will suffice, but i'm more interested in a broad boost curve and a wide powerband.

    i doupt you could ever convince me to go steeper than 3.90:1 gears on my "daily driven" car. if i'd ever put those.

    intercooled twinscrews aren't cheap now a days either. "you have to pay to play." my ideal 2.1l KB would cost me just over $6k installed. if not slighty higher.

    about the 700+ hp street cars, my real "want" is a torque monster 5.4l with an F1. sadly, that isn't going happen anytime soon.