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Thread: Supercharger throttle body placement question

  1. #1
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    Supercharger throttle body placement question

    Ok I've read best way to install SC is between TB and engine. My question is how far from engine is to far for the TB. My SC is going to b bolted to exhaust side of engine. I will run SC output tube under engine with about 3 ft till intercooler then 1.5-2.5 ft maybe of tubing ran to intake. I can find somewhere before SC to put TB but it just seems like a lot of air between TB and intake. Wondering if that will kill throttle response or no boost power/low end low speed torque?
    Thanks everyone!! :-) ......code 59, 749, 2.3l quad-4, m56 SC (I think it's a m56) eaton 18??? I'll look and if anyone would like pictures of the set up to tell let me know :-) thanks again!!

  2. #2
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    This is not a good plan. How do I know? I drive one at least three times a week. You're spot on with the observation that there will be a lot of air between the throttle body and the intake!

    The remote mount supercharger is cool, but the issue is the throttled volume, which is VERY large in this kind of setup. You won't loose much response, you won't loose any boost, but you WILL loose the ability to control the idle speed with anything other than a vague guess, and it will be very hard to get it to return to idle from any kind of RPM's. You can either run a dual-throttle setup, requiring syncronized throttles on the OE intake manifold and on the inlet of the supercharger, or you need to reduce the throttled volume to the minimum possible. Often times a single-throttle setup will stall at stoplights or when pushing the clutch in, or even coasting down the road.

    You can determine for yourself how bad the idle will be, by unbolting the throttle body and adding in the length of pipe and the intercooler needed, and then attaching the throttle body to the inlet of the intercooler-rev it and see what happens. If you run a very small intercooler and very short pipes, you can make it work better, but it'll never really be "good" this way.

    Also, Eaton blowers are M24, M45, M62, M90, M112, M122. I've never found an M24 for sale anywhere, but M45's can be had off Mercedes smaller Kompressor cars, as can M62's. These are both remote mount setups, but Mercedes took great pains to minimize all the throttled volume and even then they are marginally stable.

    Other M62's can be found on first-gen 3800SC's, and on Nissan VG33ER-powered Xterras and Frontiers. M90's can be hand from Supercoupes (another marginally stable remote mount setup) and second-gen 3800SC's. M112s and M122s are from the bigger Ford V8s, and there are "H122" variants out there from the Ford GT.

    Given that your engine is a small displacement volume, you will have a much harder time getting it to be stable. The Supercoup's 3.8L engine is really the best example of this kind of setup and you can see how they went to great pains to keep the volume low-you need to keep the total throttled volume equal to or less than the displacement volume of your engine. I would try to find a Mercedes CLK230 Kompressor and make sure my pipe lengths and intercooler are as small or smaller than that car-it's the only production car I know of that has successfully used a remote-mounted, air-to-air intercooled supercharger with the displacement in the same range as yours.

    Best method for this (voice of experience here) is to mount the supercharger directly to the intake manifold, and use an air-to-water intercooler if you plan to run more than 8PSI of boost with an Eaton blower. It's just that much easier to make it run the way you want it to run. The only reason not to do it this way is if you just don't have the ability to cut and weld the intake manifold. If you can't do the intake fab, you're better off to try and mount a turbo to a short header, and go that way-it will be much easier to tune and easier to fabricate due to the all steel construction not requiring expensive welding gear-a cheap flux-core welder *can* do the job if you take your time and don't try to weld things that are too thick for it. Turbo headers don't *need* to be made from 1/4" thick pipe...even 14 gauge tubing is fine if you support the turbo properly with a brace to the block.

    BTW, did you ever get the engine running properly before? I recall you had some fueling issues with this setup.

  3. #3
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    Yes after I switched to code59 and a 749 ecm it has ran consistently across outside temps hot to freezing. I'm wondering if the fuel pump I am using is over running stock fuel pressure regulator making fuel pressure a tad to high. I used a stock fuel pump from a 94 Buick roadmaster station wagon with a 5.7 lt1. If not my fpr is not working right. Identifix info says 43-50 fuel psi is the spec but that's an awful wide range it seemed to me but mine is 48-50 and jumps to53-55. I have an adjustable reg sittin here but gotta find time to thread fuel rail to install. I'm having much better luck with this ecm and code59. I can watch for spark knock now, got timing table goin in the right direction. 8B I got 1 knock signal and it would retard the timing in every cell, so much so that I could barely drive it before I found it was doing that. I'm still workin out some bugs like PW is bouncing off of .57-.63 with afr at 13.1-14.2 at idle so gonna try playing more with injector offset vs bat volt or lowering FP. Gonna do a lil reading on PW and that offset table on the 59 forum before I do either. But it does run much better and consistent as one can with the tune it's running on. With 8B I blew the doors off a BMW Z4 for the first 2 gears, stuck my head to the seat. But it was cold outside and the next morning it was warmer and ran like crap!! Now I hit a sweet spot in the tune and it's there no matter the outside temp. But yes it's running much better!!! :-)

    I'm not 100% sure but but what I found on the web is it's a m62. I had a 1999 c230 sport, that's where I got SC, intercooler and recirculating valve, it had a valve to switch to NA intake tubing and a blow thru TB. I should have kept the damn valve!!!!! I knew I would need the thing. My original plan was to blow thru TB but forgot about brakes so that's y I ask. I can weld SS, aluminum whatever but I can't drive SC on the intake side of engine without some kind of remote drive. I also have a series 2 or 3 SC from a early 2000's Buick. And a turbo, turbo numbers say it's from a 340hp flat 6 cyl Cessna airplane, haven't learned how to read turbo map yet. The Buick may be long enough to drive from intake side. I'm pretty sure I can make it a blow thru and still have vacuum but making my throttle plate a taco shell scares me, then it'd be open throttle panic!!!!! I looked at vacuum pump for brakes so I'm concidering everything at this point

  4. #4
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    Benz had two ducts coming out of air box, one had an electric valve that looked like it would open and bypass SC completly or cutting off NA duct for boost. Anyway I'm really just trying to keep it simple with easy maintenance in mind, didn't want to add cool dual TB setup or those electric TB's from Benz if I didn't absolutlly have to but gotta do what u gotta do. I cuss vehicle engineers all day long I don't want to b cussing myself anymore than I already do :-) so how's the dual sync TB work? All air come through SC TB and then TB on intake is blow through?
    Last edited by BigBanks78; 2 Weeks Ago at 12:03 AM.

  5. #5
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    I've taco'ed a throttle plate with the M62 on mine, it was not fun.

    Suck through throttles or dual throttles-blow through throttle with a PD supercharger with no bypass valve is dangers. Regardless, you MUST MUST MUST use a compressor bypass valve with any Eaton blower! Not bypassing the blower at idle and low load will result in the blower overheating and seizing solid. Leave the blower unbypassed at idle for five minutes-it'll lock up solid from the heat. Never mind the stop-and-go of traffic...that'll lock it up even faster!

    I have two seperate throttle cables operating two throttle bodies-a 60mm on the intake plenum, and an 88mm on the inlet of the supercharger. I modified the inlet of the M90 case to allow the full 88mm throttle. The quadrant arms are different sizes on the two throttle bodies, so I had to make matching quadrant arms to make sure the two throttles opened at the same rate as I pushed the throttle pedal.

    You should be able to mount the blower anywhere you want-but the merc blowers are not what you want to base your design on. That clutched pulley wears out and won't engage, and if you're like 99% of all the people who want to use it specifically for that, I've got news for ya-no mad max style blower engagements. It'll immediately burn up the clutch and will never work properly again after that. The blower is normally held engaged by the computer, and the computer DISENGAGES it over a few thousand RPM-it's only working for idle-3000-3500RPM and then the computer drops it out and bypasses it. Also, it's very expensive to get an interchangable or any other size pulley for the blower...500$ plus last I checked into it. No other systems will fit it directly.

    Also, the blower doesn't have to align with the intake. You can cut and fab a new plenum to mount the blower, and put it anywhere you please to get the belt lined up, from what I remember the intake side of a quad-4 has lots of room under the intake manifold.
    Last edited by Xnke; 2 Weeks Ago at 12:17 AM.

  6. #6
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    I read most of ur reply but not much time at moment but wanted to show u drawing and see if u thought it would work. I just changed starter and there isn't room under intake without moving alternated or a/c. In a Fiero there's even less room there plus stock belt is to narrow and not enough room to push beyond the harmonic balencer. I have a 2 to 1 pulley drive. Not going to use clutch, gonna lock it. I have a 13 inch lathe but haven't tried to make a pulley yet.
    I'll reply after a bit with more.

    Ok can I sync 2 TB's in this way and it work, sync one to the mainTB to close NA filter as main TB opens. #1 on drawing closes as #2 opens. And what about running air from after the inter cooler back thru SC when not in use?? Yes I'm gonna use all the safety stuff/valvesimage.jpg

  7. #7
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    Ok is the throttle body on SC to slow down the air when you let off throttle? Where did route your bypass valve to/from? I readthat if you recirculate the air back thru SC that it would help keep it cool when not in use. This is my first boosted build so I'm sure I'm not familiar with all my options for boost control and configurations. I tried to google for diagrams but didn't find much variety. But I'll look up the setup you are talkin about.

  8. #8
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    The supercharger inlet needs to be throttled for both noise (Don't even argue this, it's so loud you won't want to drive the car...130dB+!) and to remove the 45 horsepower load on the engine from running the supercharger at full VE. The bypass is not needed to prevent throttle plate damage-it's to prevent the blower overheating when you have the inlet throttle closed. A positive displacement blower with a closed throttle will try to pump that 20kpA vacuum behind the throttle down to -60kpA, and it will fail to do so! But, that won't stop it from trying and it will get VERY hot as it attempts to do this. Hot enough to cause the rotors to rub and sieze in the case-so you need to have the bypass valve unload the compressor.

  9. #9
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    I will b using a bypass valve, when I say recirc valve or BOV I mean bypass valve but I was thinking the bypass valve would do double duty, release pressure when over boosting and bypass SC when not using. I can get an external valve like that right? If so can do you mind giving me some good terminology to search and some specs to go by? I see BOV's on web, some look like they have a 1/8" vac hose nipple on both sides of the diaphram but they don't have image.jpgmuch of an explanation to wether they can b controlled both ways. I already have a bypass valve control solenoid off a Buick 3800. I get it about noise. I watched youtube video of a vw with this SC, bov vented to atmosphere and I can't do that loud PPSSSSSSTT every time I shift so was going to vent mine back to inlet. I will put TB on inlet no argument :-).....do I route bypass behind sc tb? What would be a minimum tube ID for bypass tubing? Will the engine pull a vacuum if through SC TB when SC is bypassed, I mean using the SC TB as only air inlet in the system? I should be able to control the bypass valve in all ways with the 749 right? With the wastegate control pids....

  10. #10
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    You need the one sold specifically for supercharger use-the poppet type do not flow enough to be useful in a compressor bypass valve.

    The one from the Mini Cooper S would work just fine:

    http://www.ebay.com/itm/Mini-Cooper-...-/191986610258
    http://www.ebay.com/itm/2002-2006-Mi...-/262896611747

    You might look at the stock eaton blowers on Ford and GM stuff for your ideas on where and how to plumb it.

  11. #11
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    Ok GREAT :-) Thank you!! I'll head out to a pull your own part yard and c what I can find. Looks like may be able to fit a vacuum diaphragm to a TB and use.....maybe.....anyway thanks, oh I will b able to get vacuum when supercharger is bypassed right? Want to make sure I have brakes!! :-0!!

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