High boost SC14 supercharger

[DR Frankenstine]

Finaly got the hilux up and running after a 4Y efi swap from carby. While I was at it i fitted a SC14 supercharger. Anyway everythings running great and the plumb back BOV works a treat with no preasure build up while idleing. when I button off the throttle at revs there is no preasure spike. However once the revs hit 3000 the boost preasure is at 1.25 BAR which by my calculations is about 17lb boost. It holds this boost all the way to the limiter. This seems a bit high what do you all think.

[MART]

Pics please , Cheers Paul.

[mnemonix]

Don't the sc14's have issues with heat generated from higher levels of boost?
I was warned that 10-12psi was "a happy place" for mine, but they usually die at 14psi and above.

[DR Frankenstine]

Don't the sc14's have issues with heat generated from higher levels of boost?
I was warned that 10-12psi was "a happy place" for mine, but they usually die at 14psi and above.

I believe they die and blow seals etc because people dont plumb them in properly. They require a plumb back valve to stop preasure build up at idle and spiking on throttle release. What you are saying though makes sense with the higher boost and heat though. I might try a weaker spring in the BOV and get the boost levels down to about 10. should make the motor happier to.
Anyone want to vollunteer an email addy to me who, knows how to put up pics, and post a couple for me

[MightyMouse]

They die at high boost because the heat of compression has to go somewhere.

Even though the charge air carries a significant portion of the heat the case just can't help but get hot - and its got limited ability to dissiapate heat, as it has no specific cooling mechanism.

Run at more "normal" boost its desn't overheat.

P.S. - make certain you use VERY HIGH QAULITY lube in the blower drive gearbox. The toyota stuff costs a fortune but castrol make a high quality synthetic gear lube thats perfect. Its still dear but......

[berad]

Obviously it is belt driven, if you put a larger pulley on the blower it will Produce less boost, a bov type setup is just bleeding the boost from the motor, but the blower is still boosting/spinning at higher rpm's causing heat.

The 1ggze which is where the sc14 came from must have a larger diamater crank pulley than the 4y, so adding a larger diamater pulley to the sc14 will slow the rpm down.

[mnemonix]

A couple of related issues off the top of my head.
- The sc14 has a physical limit of around 10-12k rpm.
- The rotors are teflon coated, and tend to delaminate/deteriorate higher temps. I'm sure that is what I was warned about.

Do the maths to work out the pulley ratios that should produce the pressure you want.

[DR Frankenstine]

Obviously it is belt driven, if you put a larger pulley on the blower it will Produce less boost, a bov type setup is just bleeding the boost from the motor, but the blower is still boosting/spinning at higher rpm's causing heat.

The 1ggze which is where the sc14 came from must have a larger diamater crank pulley than the 4y, so adding a larger diamater pulley to the sc14 will slow the rpm down.

Can I have a bigger pully and still run the a/c type clutch

[berad]

use other pulleys with the same clutch, i remember the boys who ran them on other motors used a el falcon a/c pulley, but that used to turn the boost up so you need to find the diameter you need, then find something that suits.

Castlemaine rod shop sell a few different pulleys for them.

[DR Frankenstine]

Thanks

The pully on the crank is 450mm round the pully on the s/c is 400mm round, can someone with a brain work out what the s/c is doing when the motor is doing 5000revs. I work it out at 5625 is this right and if so why such a high boost.

[mnemonix]

I can't see why you're getting such a high pressure, but below are the calcs I use to determine pulley size. Might be useful.

To convert perimeter to diameter use P / PI (3.14159)
Crank pulley 450mm perimeter = 143mm diameter
SC pulley 400mm perimeter = 127mm diameter
Which equates to a 1.125 pulley drive ratio.

Then you can work out all you need to know with 3 calculations:
The figures below assume a 1.6litre engine running 12psi and reving to 6500rpm.

First calc (engine air requirement in litres per minute)

multiply the engine size in litres x max rpm
1.6 x 6500rpm = 10400
divide by 2 because engine only breathes every second revolution
10400 / 2 = 5200

this is the engines air requirement in litres/minute at zero psi.



Second calc (boost ratio)
Add the desired boost pressure (10psi) to 14.7 (atmospheric pressure)
= 24.7

divide this by 14.7 to calculate the boost pressure ratio (24.7 / 14.7 = 1.6802


Third calc (Actual air requirements at desired boost)
multiple the boost ratio by the litres/minute obtained for zero psi to calculate the air required by this engine at the desired boost.

1.6802 x 5200 = 8737 litres/minute @ 10psi boost.



SC14 has a 10,000 - 12,000 rpm safe maximum operating limit.
It has a swept volume of ~1.5litres per revolution.


Misc Calculation - Supercharger RPM
Divide the desired air flow (8737 litres/minute) by the swept volume of the supercharger (1.5).
This will tell you the maximum speed the supercharger rotors must be run at to produce the volume required.

8737 / 1.5 = 5824rpm at the supercharger.



Misc Calculation - Pulley size ratio
Divide the supercharger rotor RPM by maximum desired engine RPM to get the pulley drive ratio.
5824 / 6500 = 0.896

[love ke70]

as mnemonix said, its the teflon coating that delaminates off the blades at higher pressures due to excess heat and what not and then the whole thing just lunches itself.

definately wont last at those pressures.
for more info, have a look on toymods.net.
mnemonix seems to be on the right track though, im quite impressed your getting those pressures out of the SC14, especially with the ratio you mentioned, doesnt seem that crazy.

[DR Frankenstine]

Im gonna put a brand new boost guage on it to see if it reads different. I hope so

[DR Frankenstine]

Just put the Brand new boost guage on.It's sitting on less than 1/2 lb boost at idle, If I open the throttle slowly the boost creeps up slowly ie 1500 revs has about 3 lb boost 2000 has about 5, 3000 about 10, 4500 has 15lbs boost. However if I stab the throttle it instantly jumps to about 6 lbs off idle and by 2000 has about 10, by 3000 its at 15-16 lbs and holds that to the limiter. Hopefully it will be ok.

[11_evl]

Maybe your colder conditions have helped you so far.

[DR Frankenstine]

Maybe your colder conditions have helped you so far.

Yea but planning a cape york trip next year.. Maybe ill just keep it turned off.

[MART]

Where is your boost gauge located , it will give false readings in the wrong spot and have you equalised the blower by adding boost pressure to the small pipes arround the blower to stop the seals blowing out , Cheers Paul.

[cplux]

what efi setup are you using I have had an sc14 in my hilux for a few years now. I am overdriving it with a custom crank pulley and by my pressure gauge boosted to around 12psi max with my old efi setup which was TBI and not entirely sure what it boosts to now as I have not really tuned it to suit my new efi setup (factory 4y-e modified significantly)
Are you measuring your intake temp or have an intercooler mine intake temp used to get extremely hot without one (talking 100 plus degrees after prolonged boost) it now sits between 30 and 50 degrees.

Good to see someone else trying this on a 4y, the sc14 on mine has made a monumental difference to power.

[DR Frankenstine]

Where is your boost gauge located , it will give false readings in the wrong spot and have you equalised the blower by adding boost pressure to the small pipes arround the blower to stop the seals blowing out , Cheers Paul.

No I havn't added boost to those pipes, I was told to just link em all up. Thanks for that info I will now. The Boost guage is in the pipe between the S/C and throttle body.

[DR Frankenstine]

what efi setup are you using I have had an sc14 in my hilux for a few years now. I am overdriving it with a custom crank pulley and by my pressure gauge boosted to around 12psi max with my old efi setup which was TBI and not entirely sure what it boosts to now as I have not really tuned it to suit my new efi setup (factory 4y-e modified significantly)
Are you measuring your intake temp or have an intercooler mine intake temp used to get extremely hot without one (talking 100 plus degrees after prolonged boost) it now sits between 30 and 50 degrees.

Good to see someone else trying this on a 4y, the sc14 on mine has made a monumental difference to power.

I bought a Tarago with a 4y-ec in it, I rebuilt it and fitted that on board. Next job is to have it dynoed to see what the temps and fuel mixtures are doing.
most likely have to get a tunable computer and new injectors and a fuel preasure regulator, Will see

[cplux]

do you have the throttle body after the supercharger?? I found when mine was originally that way that you can get massive pressure spikes/high readings. I now have a modified commodore v6 throttle body before the supercharger.
would be interesting to see how the factory injectors do infact hold up, I upgraded mine to quite a bit bigger ones (cant remember what flow, will have notes somewhere) as I had found with the TBI setup that I had to have the injectors going flat out and they were struggling. I think they were two 400-440cc injectors.
If you drive it hard your economy will suck.

[-Nemesis-]

Where is your boost gauge located , it will give false readings in the wrong spot and have you equalised the blower by adding boost pressure to the small pipes arround the blower to stop the seals blowing out , Cheers Paul.

No I havn't added boost to those pipes, I was told to just link em all up. Thanks for that info I will now. The Boost guage is in the pipe between the S/C and throttle body.

You need to mount the gauge line to the intake manifold, to see what sort of psi you are getting in the actual engine.

You shouldn't really see boost in the manifold untill the engine is under load. My blower would be capable of multitudes more air flow than yours, but I can't get any positive pressure in neutral no matter how hard I rev it.

[DR Frankenstine]

Where is your boost gauge located , it will give false readings in the wrong spot and have you equalised the blower by adding boost pressure to the small pipes arround the blower to stop the seals blowing out , Cheers Paul.

No I havn't added boost to those pipes, I was told to just link em all up. Thanks for that info I will now. The Boost guage is in the pipe between the S/C and throttle body.

You need to mount the gauge line to the intake manifold, to see what sort of psi you are getting in the actual engine.

You shouldn't really see boost in the manifold untill the engine is under load. My blower would be capable of multitudes more air flow than yours, but I can't get any positive pressure in neutral no matter how hard I rev it.

Interesting!! I was told to run the boost guage after the S/C but before the T/B. Apparently this way you can see exactly what the S/C is doing and you can make sure there are no preasure spikes etc when you close the throttle. If you have the guage in the intake manifold you wont see the preasure spike but that doesn't mean its not there. These high spikes are what kill S/C's and make them stall and belt squeel etc. you can also see if the S/C is keeping up with the engine's need's. When you rev out the engine and see preasure drop you know the S/C is not keeping up, Indicating a problem.. This advise was given by a high performance engine tuner....

[mnemonix]

I've never run a gauge anywhere but in the inlet manifold.
The reasons you mention for having it immediately after the supercharger are valid. However we're talking about a $400 used supercharger here, not a big dollar 8/71. This offsets a lot of the reasons you mention.
You can avoid pressure spikes with a properly configured bypass valve + recirculating blowoff valve.
Much better to measure pressure in the inlet manifold to see what boost your engine is recieving, after losses from intercooler/pipework etc.
If you observe a pressure decrease under rev's with the gauge at the SC, you'll still witness it when measuring pressure at the manifold.

[-Nemesis-]

Yeah that advice is a bit odd, you're engine is more important than knowing what pressure is in the intake pipe!


Just add one of these to the intake pipe and you don't have to worry about spikes or whatever

http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0460423454

Vent to atmo and it will pshhhh like a BOV (same thing) or vent back to intake before charger for silence. For a few more $ you can buy an adjustable one (better quality), I use it with no dramas on my blown 8

[Spike_Sierra]

Vent to atmo and it will pshhhh like a BOV (same thing) or vent back to intake before charger for silence. For a few more $ you can buy an adjustable one (better quality), I use it with no dramas on my blown 8

these superchargers have gotta be plumbed back. when i first hooked up my supercharger i didnt have it plumbed up, and at idle its constantly pshhting.. After i plumbed it up, its much better and makes things a lot more quieter. Would like to have a look at this lux Dr. You still working on mobile moonah?

[DR Frankenstine]

Yeah that advice is a bit odd, you're engine is more important than knowing what pressure is in the intake pipe!


Just add one of these to the intake pipe and you don't have to worry about spikes or whatever

http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0460423454

Vent to atmo and it will pshhhh like a BOV (same thing) or vent back to intake before charger for silence. For a few more $ you can buy an adjustable one (better quality), I use it with no dramas on my blown 8

I have a plumb back BOV in line already and works perfectly. I will use the port for the boost guage to run into the 3x S/C equalization pipes and T into the manifold for the boost guage. How's that sound.

[DR Frankenstine]

Vent to atmo and it will pshhhh like a BOV (same thing) or vent back to intake before charger for silence. For a few more $ you can buy an adjustable one (better quality), I use it with no dramas on my blown 8

these superchargers have gotta be plumbed back. when i first hooked up my supercharger i didnt have it plumbed up, and at idle its constantly pshhting.. After i plumbed it up, its much better and makes things a lot more quieter. Would like to have a look at this lux Dr. You still working on mobile moonah?

No mate left there ages ago. I run my own business now. (Tas Mobile Caravan Service.) spread the word. The lux is off the road again now doing the suspension and steering before it goes to the Dyno. Can't wait to see the final figures, S/C off then on especially after they have done all the neccesary final tuning and adjustments. If you want to catch up email me mknissan@bigpond.com and ill send you my Address and phone number

[-Nemesis-]

Vent to atmo and it will pshhhh like a BOV (same thing) or vent back to intake before charger for silence. For a few more $ you can buy an adjustable one (better quality), I use it with no dramas on my blown 8

these superchargers have gotta be plumbed back. when i first hooked up my supercharger i didnt have it plumbed up, and at idle its constantly pshhting.. After i plumbed it up, its much better and makes things a lot more quieter. Would like to have a look at this lux Dr. You still working on mobile moonah?

Yeah, technically they don't have to plumb back (unless you have an air flow meter before it), but they don't sound too great when you're decellerating and they're shhhhhhhhhh-ing the whole time

[barbz]

Photo for dr frank