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Discussion Starter #1
Gday all
I have been looking into the SC-14 supercharger to actually put on a holden 6. Its cheap reasoanbly available and i am only looking for low boost.

My big question which i have done hours of research and not found an answer to is at what rpm does the supercharger reach max boost? (not absolute max but around the 8psi mark) From what i have gathered the supercharger would be spinning at about 5000rpm

Other question is what hoses or wires run of this supercharger?

Thanks
4dice
 
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Discussion Starter #5
sc-14

Gday again
I am not doubting that it boosts all the way to redline, i am inquiring about at what rpm does it reach close to its 8psi. The rpm is usually about 70% of its max rpm.

So for example supercharger that does 8psi at 10 000rpm redline normally produces around 8psi at 7000rpm.

I am wondering what the sc-14 does it at?

Yeah i searched the 1g-gze engine got some figures about that engine but not much supercharger specific.


This is not going on a MR2 i just found some really helpfull posts about this supercharger whilst on this site and thought some one may of been able to help me

Thanks
4dice
 

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The amount of boost is dependent on the engine it is boosting. Boost is built because the supercharger is pushing in more air than the engine would normally pump, how much more will determine your boost levels. The MR2 SC12 builds 8 psi of boost at 4000 rpm engine speed (5000 rpm supercharger speed) on a 1.6L 4agze engine.

How large is the Holden 6 engine? What is it's stock horsepower? Only then can we even begin to estimate how fast you will need to spin the SC14 to achieve that boost level.
 
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Discussion Starter #7 (Edited)
boost levels

Hey

It is going onto a 3.3l (206 cu). with about 160hp at the flywheel that redlines at 50000rpm (yeah low compared to the little 4 cylinders)

Dont want any more then 6psi of boost to ever be produced, looking for about 4psi at 3000rpm

I thought the superchargers boost level would start to level of at a certain rpm, yes the boost level would be different depending on the engine size and pulley ratio being used. But always thought it would start to level off at the same supercharger rpm.

Its quite possible that i am wrong or that i just didn't ask my question clearly, shouldnt of mentioned the psi, i just thought if someone could give me an engine rpm and pulley ratio that there supercharger started to level of i could work it all out myself.

Thanks 4dice
 

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Ok since I have the sc14 I thought I'd chime in.... the big thing is going to be the size of the crank pulley in relation to the pulley on the sc14. This will determine how much boost it will do on lower rpms. For example, when I run the stock s/c pulley I reach 8-9psi at about 2200-2500 rpms, and max boost of 11-12psi by 4500-5000 ish.

Now up it to the cusco pulley, and I get 10psi under 2000 rpm... and 14psi under 3500rpm with full boost 17psi at about 4500 rpm.

Also timing will play into this, as the more retarded the motor is under boost, the more boost it will make, don't translate boost into hp though, because correct timing and less boost is more powerful than more boost with incorrect timing.

Josh
 

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Have you hit up the forums at www.toymods.net? Seeing as Holdens are only available in australia and SC14s are more common there (they got the 1g-gze soarer), they could probably warrant some more good info.
 
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Discussion Starter #10
Gday all
tarmactrr thanks for your post, When you are running the standard pulley on the SC-14 i am assuming that the 145mm pulley running at running at 1.25 crank speed?

So when your engine is revving at 4500-5000 ish the supercharger would be producing its max boost at about 6250rpm upwards

Thats pretty much what i was looking for, if you could comfirm drive ratio it would be great

I have had a really good look around the toymods site, got a lot of good information, but never got the figure i was looking for. At what supercharger speed does it produce its max boost. (around, redline normally slighlty higher)

Yes the boost level is dependant on engine size pulley ratio, camshaft, timing and probably more but it will the supercharger should always produce its max level at a certain rpm, not an exact number but close enough

Thanks
4dice
 

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A 3.3L motor can injest 1.65L of air per rotation. A SC14 turning at 1.25 times crank speed will provide 1.75L of air per crank rotation. That's only 6% more air, not taking into account VE of the engine and supercharger. Spinning a supercharger the same speed relative to the crank on a 3.3L engine on a supercharger meant for a 2L engine will not produce good results.

The 4agze 1.6L can injest 0.8L of air per rotation, and the SC12 provides 1.5L of air per crank rotation at 1.25 times crank speed, 87.5% more air. This yields 8 psi.
Given you are only shooting for 4 psi... I would shoot for the supercharger providing 40% more air as a base, giving you a rotation speed of 1.65 times the crank speed. Since your engine only spins to 5000 rpm, this shouldn't cause any problems.

edit: 4dice, let go of the supercharger making max boost at a certain rpm. That only works when you have the same engine. The second you switch to putting the same supercharger on a different engine, especially one with a very different displacement, that all goes out the window.
Oh yeah, thanks Toyota for screwing us and not giving us the 1ggze engine Soarer over here :mad:
 
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Discussion Starter #12
Thanks rallyengr
I may of got caught up on the idea, guess i was tryign to think logically but probably missing something big. I had done some calculations before and got the ratio of 1.5.

6psi is the most i want to put the engine through, with running about 4 at the 2-3000rpm range. If i could get it to achieve that psi at 1500rpm but not go over 6psi at 5000rpm it would be great

Thanks for your help
Guess all there is left is to fit it

cya
4dice
 

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4dice - you are thinking of a ( Forgive my spelling I NEVER get this right) Centrifugal type supercharger, where it basically has to spool up. An ATI, Vortech, or Paxton is of this type. It reaches boost based on RPM.
With a roots type fixed displacement SC like the toyota blowers, and Eaton, and a few others there is no spool up.. as soon as the gas is hit, the boost is there. You should have about the same amount of boost at 1200 rpm as at 5000 RPM. The boost will not be 100% the same everywhere becasue the VE of your motor dictates that where your torque peak is right now will probably be lower boost than at redline where the VE is falling off.. IE more restriction from the head means more pressure before it trapped between it and the SC unit.
With that all said, a 3.3L motor spinning at a max of 5000 RPM does sound doable as rallyengr suggested. The max speed of the SC unit is a point of arguement with the over drive pulleys people use. I use a 180mm overdrive, common wisdom only a few years ago said 170mm was the biggest.. then 175.. then 176, then 180.. so who knows. But if you want to produce 6 psi of boost at 5000 rpm, you need to figure out teh gear ratio to get 6 psi, and then use 5000 RPM multiplied by the ratio to determine SC speed.
For the GZE motor with the SC12 it spins at 120% crank speed so ~9250 rpm max
wit the NST pulley like I have it spins at 150% crank speed so ~11,500 rpm max

So 10,000 RPM for the SC14 is probably reasonably safe for it...
that means you could get 2.8 liters of air per motor revolution max.. and ingest 1.65 meaning a max boost of about 10 psi. If you want to hit 6 max then you want about 2.33 liters per motor rev.. so to get 2.33 from 1.4 you need to spin at 165 - 170 % of crnak speed.. IE that is your pulley ratio you need.. 1.65:1 crank to SC ratio.
 
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Discussion Starter #14
Thanks

Thanks alot for clearing tat up in all of my research about superchargers i must of taken some centrifugal info as roots style. I have read into all the different types and the roots definatly seems the easiest to install and good for what i want, which is good talk low to mid.

If i will get about (i know we arent talking definate numbers) from around 1500-5000 i will only run 4psi, then engine has been rebuilt with all the performance gaskets bearings and pistons, even stronger rods,and of course a alot of head work.

I need to work out valve overlap on my camshaft so i can take that into consideration, possibly even get a forced induction cam.

If some one could tell me the amount of valve overlap i will try and work out the loss of psi because of it. I would be thinking that its just 1 degree?

part num 356661
Valve timing IN.25/65 EX.74/26
duration 270 280
.050" DuR. 204 214
valve lift .420" .442"
power range 1900 4800

What is the stock size pulleys on the sc-14? or so they vary between models?

Thanks for the help
4dice
 

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I know your not going to like this but why not get rid of the old holden donk to start off with, they are a reliable motor but they definately arent the most powerful to start off with, why not look in to a complete 1ggze conversion or something like the 1jz? I know its a bit more work but its a better base to start from. Whats this going in to? A Torana or Commodore or some other old Holden
 
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Discussion Starter #16
Hey sikmr2
I am used to getting told get rid of the 6, normally beign told to throw a 8 in. I havent done the research into it but i dunno if a 4cylinder would have the torque to make it a good conversion.
My old 6 only has a stock crankshaft so its far from stock, holds its own against the modern 4 cylinders. I am not doubting that the newer 4 cylinder engines could produce more hp and even torque but it doesnt really interest me. I am only 17 and have only just done the engine thats in the EH station wagon.]

With putting a modern engine in i would also have to change gearbox diff driveshaft and brakes and thats not mentioning gettign everythign in the engine bay going.

Thanks alot for all the help
4dice
 

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Ah ha, an EH, nice choice of a holden, thats about the only holden i would ever go for. If ya keep the Holden 6 ya can still make some decent power if built properly, a guy i used to work with had a LC Torana with a 186 heavely modified and im pretty sure a T03 turbo. That thing screamed and ran flat 11's at the drags but he poured alot of oney and time into it. Ive got nothing against the old motors dude, but with the newer technology thats around its just a better starting base and mostly cheaper with all the jap imports around
 
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Discussion Starter #19
Yeah they get some crazy power out of the old holden straight 6's, normalyl with big boost and rebuildign engine very often aswell. But no with a cleica 5 speed and a worked engine they go pretty hard.

Sorry my mistake about the modern 6, i dont know that many engine codes


cya
4dice
 

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when i had a SC14 on my GZE i was running 18-21psi with a 179mm crank pulley
 
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