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Discussion Starter #1
so yeah, thinking of ditching the vf35 in my 1.6l dohc lc2 accent for an eaton type s/c, now i know to expect a loss at top end, but just how much?

i have ~240whp now and i want to run the same sort of boost ~15psi @ 8.5:1 c/r with microtech ems. ill keep the air/air intercooler and add water injection as well, but will i losse a heap of power?

im prepared to sacrafice a little top end coz the draw of instant boost is just too much! i heard 2/10ths of a second is not an unrealistic spool time!

with extractors and a 2.5in zorst what sort of 1/4mile times would one expect from a good setup???
 

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I would stick with the system you have now. If you plan on mounting the eaton where I have seen some pictures of it (over the exhaust manifold mounted to the power steering pump mounts) your going to have to deal with a ton of heat. If your going to make a custom IM manifold and install it where a roots type system is suppose to go you will not be able to keep the air/air intercooler. Again with the heat. That and the piping to the intercooler and back will take that instant boost you are looking for away. Not to mention if you are trying to get better 1/4 mile times a turbo would do better anyway, if you are driving it right. The s/c would be easier to make better time in an autoX like event. I find the power output you have with your current setup is a little on the amazing side as it is.. get a little more greedy and you might find yourself without a motor to boost or no transmission to put the power to the ground.
 

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Could we get images of your engine bay and the Eaton unit you are thinking of mounting?
 

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Its more than a little top end. Taking an example from Miatas, as doug did above: the Jackson Racing supercharger kit at 6psi makes 130-140whp on the 1.6L miata. On the same vintage miata, the GReddy turbo kit at 6psi makes an easy 160-180whp. The power disparity only grows as you up the boost, as its going to take more and more hp to turn the blower. A 12-15psi turbo miata car makes 240-280hp, while the supercharged cars are barely huffing out 180whp and SCORCHING intake temps.

If you want better response, redo the downpipe, go with a smaller and more efficient turbo (Garret GT series for example), and spend more time tuning the ecm.
 

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Discussion Starter #5
yes i was thinking of mounting the eaton where the a/c is bove the turbo manifold and keeping the intercooler.

as for instant power... i kind of meant at any revs. as it stands if i put my foot flat to the floor at 2 or 3k revs nothing happens... hen after a few seconds (which feels like forever) the car just snaps and claws its way out from under you! yes i can change down gears, but if im in 5th at 100km/h i have to go all the way back to 3rd and then wait a couple of seconds for the revs to get high enough. in trafic this is unacceptable as the oppertunity to pass is gone by the time i have done this.

what are your thoughts on a twin charged system then? the eaton to blow thrugh the turbo, and when the turbo starts to outflow the s/c have a bypass valve. i can see this would not only produce more power at low revs, but also spool the turbo quicker.

i wouldnt have to worry about the intake temps from the s/c at high power coz the turbo should be sucking the air out of the s/c faster than it could blow it so it wont be compressed except when the turbo is not spooled yet [at low revs] and then the intercooler and water injection can take the heat. also because its pushing more air in and thus more exhaust out, the turbo would spool a lot quicker, allowing the turbo to take most of the load quickly and minimise the time the s/c is doing the work.

of course the s/c and bypass valve (a simple check valve would work i think) would cause some restriction at high end, so i would loose some top end, but a lot less than a straight supercharger, and i would lose a little bottom end because of all the charge piping and intercooler and turbo itself being a restriction. but i would still have MUCH more bottom end than a straight turbo.

if i mount the eaton as discribed all i would need to do is take the piping down to the intake of the turbo(easy) and biuld another intake (again easy). and retune the ecu.

hmn... you can get a nice eaton for a 3.8 v6 for like $200, i could get some brackets made and piping... sounds like an idea....
 

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hey
if you do a search for this you will find it has been done before. Using a eaton positive displacement supercharger....sounds like the one you have lined up....simply leave ur current turbo setup as is...custom fab a nerw intake manifold to accept the superchardger and plumb the end of ur turbo setup (from IC) to the s/c.
search man! :)
 

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Discussion Starter #7
no. as we saw in accent1's case. that design is not the best.

i will simply fabricate a bracket where the a/c above the turbo manifold is and run charge piping from there to the intake side of the turbo. i will also fabricate a check valve so when the turbo starts to outflow the s/c the s/c dosnt restrict power.

just think of it as a very very effective anti lag device. it spools the turbo much, much quicker by forcing more air into the engine producing much more exhaust to spin the turbine. also forcing air thrugh the comressor side makes it act like a turbine too.

the more work the turbo does, the less the s/c does. this is because as the turbo spools it sucks air out of the s/c, meaning the s/c isnt compressing the air, only moving it, thus not heating it. so as the turbo spools the charge temps will come down coz we all know turbo's **** all over s/c's in efficiency.

end result should hopefully be REALLY BIG turbo power, with REALLY, REALLY SMALL turbo spool time. the best of both worlds.
 

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ur gonna blow the damn thing up before you reach full boost with either man. just make ur turbo spool lower like omgbossis did
 

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Yeah I would rather than go through all the crap and still have some of the same problems (and likely more) your running into now get yourself a more well suited turbo for your application. A smaller turbo would be a much better option, spool earlier and pump plenty of boost. Your not running a supra with 30psi....
 

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Discussion Starter #10
no im running a 1.6l accent with 15psi. to get the ultra fast spooling i want with the power i 'need' i would have to spend $10k on a state of the art variable vane, variable nozel turbo and build the engine around it.

that aint gona happen. BUT s/c's are about $150 on ebay. making some brackets wont be too hard and my engine is already suited to 15psi boost, so 10psi intercooled from a s/c shouldnt hurt. and the more the turbo boosts, the less the s/c boosts, so boost will be the same, just a little more restricted and a whole lot faster to come on.

the s/c is just a positive displacememnt pump. its NOT compressing the air then compressing it again.

its compressing the air, then as the turbo compresses more [or any] of the air from the s/c, the s/c will compress it that much less [because the turbo is sucking it out of the s/c thus reducing the pressure (i.e. boost) from the s/c] untill the turbo is just draging the air thrugh the s/c.

so as the turbo boosts more the s/c boosts less. so total boost in the plenum is limited by the s/c initialy (10psi), then by the turbo's waste gate(14psi). which is exactly what it was before i s/c it.
 

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Have you thought about a good electronic boost controller or do you have one? If you go with the super and turbocharger good luck.... If you wanted instant power you should of went with a s/c in the first place. Everyone knows of the big turbo - big lag little turbo little lag ordeal. If you have the means for the dual f/i setup go for it, other wise get a slightly smaller turbo and cope with it ....
 

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Discussion Starter #12
a s/c could never get me 240hp @ the wheels. i knew about the lag, and iv put up with it, but it has come to my attention i may be able to have the best of both worlds. and if i can, that is what i want.
 

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Good luck with the project man. I understand wanting quick spool .... Mine is spooled before Im off the clutch ;):
 

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Discussion Starter #14
thankyou, and well done! still, do you have 240hp @ the wheels? if so i take my hat off to you! and if you do, then you know why im not prepared to sacrifice much of it.

boost is addictive it tell you!

[Edited by T-WING on Oct 23, 2005 9:01 PM]
 

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Discussion Starter #16
yes the td04l was a lot quicker to spool, but how could it produce [email protected] on a 1.6l??? cirtainly not at 15psi??? id be pretty impressed if it did!

[Edited by T-WING on Oct 23, 2005 9:11 PM]
 

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But your motor is still receiving an extra 16psi of boost/air which in theory should make the same amount of power, unless of course the boost of the TD04L was dropping off top end.
 

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Discussion Starter #18
the TD04l is MUCH less eficient at higher boost. that means the air it compresses is hotter, so for the boost, less chemical energy is available per unit of volume [when mixed with fuel]

so no, at the same boost two different sized turbos on the same engine and same revs will not nessasaraly make the same power.

generally the bigger the turbo, the more efficient at making more boost.
 

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At 16psi the TD04 is still within its "acceptable" efficiency range. Go run a turbo thats under its efficiency range and then you'll also have lag issues like you have now.
 

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Discussion Starter #20
the vf35 is in its peak efficiency between 4 and 6k rpm. that is 78%. hence 172kw @ 14psi. the tdo4l is outside its normal oppreating range at peak revs at 16psi, i.e. below 60%, so top end power would be drematically less.

atm top end is all i have, but OH WHAT A TOP END!
 
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