hybridmoments

am planning to run a powerdyne BD11-AA headunit on a honda civic. (custom setup, intercooled)

i was wondering if it is possible when using an extra small pulley (i.e. 2.25") can you plumb in an external wastegate directly after the supercharger outlet to control max boost. and what would be the best way to set it up?

with the small pulley boost the supercharger would make higher boost earlier in the RPM range, but then i'd want to bleed off the excess boost and stabilize at like 8-10psi with the wastegate? so instead of making like 8 psi at 7000k rpm, i'd make for instance, 8psi from 4k rpm up.
i've been looking around for articles in supercharger forums and have seen some discussion about using blow off valves and external wastegates for this. but nothing concrete on the proper way to set it up

thanks

Schister66

it sounds like it would work, but if i think it would work, it probably won't.......lol

Tatakai

just get a turbo.. supercharges are for a steady powerband, while turbo's will give you that same amount of boost from X rpm till Y rpm. and from what i've seen, turbo setups are a hell of a lot cheaper than s/c

if you got a smaller turbo with a good wastegate, you could build 8psi by 4k

hybridmoments

already have all the components i need.
this is an autocross car. so i'm more interested in response then high rpm output

my goal with the S/c that would be much harder, maybe impossible to to with a turbo, is to make major boost very early in the rpm (like a roots or twin screw supercharger) and with a budget.

let me state my goal. make max boost as early as possible. and control the excess boost the S/c would make at higher rpm.
i'm not sure how easy it would be to make say, 8psi at 3 or 4k rpm with a turbo.
especially on a d16z6 engine. the turbo is dependant on exhaust flow
while S/C is multiplying the engine speed with pulley configuration.

lalspeed

i thought sc's hold boost through a pulley......meaning they wont boost past the set limit by the pulley... on top of that you state that you want fast response for an autox car and you go with a centrifugal supercharger? with a properly sized turbo the same goal you have set is achievable. then again you already have parts

tokesGTR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridmoments &raquo;</TD></TR><TR><TD CLASS="quote">already have all the components i need.
this is an autocross car. so i'm more interested in response then high rpm output

my goal with the S/c that would be much harder, maybe impossible to to with a turbo, is to make major boost very early in the rpm (like a roots or twin screw supercharger) and with a budget.

let me state my goal. make max boost as early as possible. and control the excess boost the S/c would make at higher rpm.
i'm not sure how easy it would be to make say, 8psi at 3 or 4k rpm with a turbo.
especially on a d16z6 engine. the turbo is dependant on exhaust flow
while S/C is multiplying the engine speed with pulley configuration.


</TD></TR></TABLE>

To pulley the blower hard enough to make 8 psi at 3000 RPM's you're going to be overspinning it so hard that not only would the shitty internal belts on the powerdyne blowers break, but if they wouldn't break the head unit would be pushing out air at 400+ degrees and detonate your motor into oblivion.

It's a bad idea. If you want autocross power swap in a bigger motor, use a JRSC, or both. Even a small turbo like a .48 A/R T3 setup is a better idea than this.

hybridmoments

thanks for the input

bigger motor, no. trying to get as light as possible. already have a good start with an 88 hatch.

yes blowers are limited by the pulley size. if i put a pulley on that will make 14psi at 8k rpm, then it might be close to 7psi at 4000 rpm
however i don't want to run 14psi. i'd like to have the ability to adjust boost pressure lower then that, without changing pulleys out. yes more boost = more heat. i'll be running a top mount intercooler and fan. i will have to see what the intake temps are though, cause i'm not sure. roots blowers heat the air up more then centrifugals from the info i've found. and can't you run some roots blowers at like 8 or 9 psi? that is going directly into the engine. no intercooler!

i'm definitely not going to spin it to more then 45k or 50k internal RPM at redline. and this isn't going to be a daily driver. so if the S/C only sees that at the track or autox, then i'll be fine. i think i'm capable of shifting at 6k rpm getting to the autox course,which would keep the S/C spinning within acceptable limits.

i'm not trying to go super crazy overspinning. somewhere between 39k and 45k internal rpm are said to be the safest with the powerdyne. with ceramic bearings and kevlar belts i've heard 60,000 internal rpm is possible. can also get it converted to internal Gears instead of belt driven. but i'm trying to stay on somewhat of a budget for now.



Modified by hybridmoments at 1:41 PM 3/17/2006

hybridmoments

LALSPEED

this is a totally custom setup. S/C is going to be mounted behind engine. outlet of s/c thru intercooler to throttle body is going to be probably less then 3 feet total.
yes you are limited by pulley size. what if i have a pulley that will make 15 psi at 8k rpm? wuold that equal 7 psi at 3-4k rpm? not sure but would be close

i'm trying to see if i can limit boost with a wastegate or some device, getting the widest power band possible. if i can make constant 8psi from 3k rpm up then it would be very interesting.
i'm trying to do something that maybe not many people have done, or no one even. and on a d16z6 honda.
it's an experiment. i like to build ****, fabricate, think outside the box. it might not work, but if no one tried anything we'd still be cruising around on horses.

lalspeed

as for the ability to hold boost off an sc, im not sure about that. how about some some sort of pop off valve. im not sure as to their internal working but the concept of it is what your looking for. i believe it will limit the boost after the blower though. but in any case goodluck with the project

hybridmoments

i've seen a few things about using blow off valves right before the throttle body. i guess i will experiment with that.

not sure how closely it would match how they work with a turbo system. they reference vacuum off of the turbo compressor side.
wonder if referencing vacuum from the S/C (only has a compressor side) would work similar