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Old 03-20-2019, 02:55 PM   #1
pcampbell
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Default Vortech supercharger for ~400whp? Si Too big?

I know nobody has ever done this but I plan on fitting a V3 Si to EJ253 SOHC heads and running it to impeller redline (50k rpm), thinking somewhere around 22psi at 6800rpm. I think 500whp is possible but not set on it.

Does anyone have any thoughts as to whether this supercharger will be too large for (most likely ported to some degree and/or running larger valves) EJ253 heads with Delta 1500 cams?

Here is the compressor map:
https://cdn.shopify.com/s/files/1/07...87759233695377

I'm thinking ~12psi (~1.8 pressure ratio) it'll flow about 40 #/minute @ 6400rpm. (note - I currently run a smaller SC at 12psi and its around this much...) that'd be well to the right of the surge line.

At impeller redline , perhaps 22psi , somewhere between 60 and 70#/minute seems realistic?

It compressor surge something I should be concerned about? i.e. motor can't flow enough for the SC...
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Last edited by pcampbell; 03-13-2020 at 04:30 PM.
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Old 04-04-2019, 02:36 PM   #2
Adel747
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Default Turbo upgrade is more safe and easy

Better to go for turbo upgrade/ supercharger have so many problems and always get heat or belt get cut , i see turbo a better and safer choice ( my opinion) cause i saw boys getting problem with supercharger alot , so i hate it ***128517;
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Old 04-06-2019, 07:39 AM   #3
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I already have the supercharger here to do it. A huge turbo would have been cool too though.
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Old 04-06-2019, 12:26 PM   #4
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I don't know if anyone will be able to answer the question about the SC not much has been done here about them mostly due to cost. Your best bet is to ask vortech, but I don't really know if they have the knowledge to answer that question. the knowledge base just isn't there if you know what i mean
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Old 04-06-2019, 06:30 PM   #5
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Default Vortech supercharger for ~500whp? Si Too big?

I will ask vortech. Dunno if anyone has ever put a v3 Si on a 4 cylinder. I donít really know why not though as long as it flows decently.
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Old 04-07-2019, 08:20 AM   #6
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Quote:
Originally Posted by pcampbell View Post
I will ask vortech. Dunno if anyone has ever put a v3 Si on a 4 cylinder. I don't really know why not though as long as it flows decently.
yeah totally, it might have more lag just because of the nature of things, but like a big turbo, once you're in boost its all go!!
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Old 04-07-2019, 09:13 AM   #7
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Quote:
Originally Posted by pcampbell View Post
I will ask vortech. Dunno if anyone has ever put a v3 Si on a 4 cylinder. I donít really know why not though as long as it flows decently.
I highly doubt anyone has with much success, its large and not as efficient as a turbo.

My friend I race with runs one on his 5.0 V8 and my turbo 4 cylender makes more whp/wtq across the board
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Old 04-30-2019, 06:45 AM   #8
pcampbell
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Default Vortech supercharger for ~500whp? Si Too big?

I donít think anyone has ever tried!

A V8 with low boost could certainly have less HP than a high boost H4. But thatís a very general comparison.
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Old 04-30-2019, 07:45 AM   #9
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Quote:
Originally Posted by Adel747 View Post
Better to go for turbo upgrade/ supercharger have so many problems and always get heat or belt get cut , i see turbo a better and safer choice ( my opinion) cause i saw boys getting problem with supercharger alot , so i hate it ***128517;
^Bizarro superman like words here
make sense a lot. . . .me like grammer two
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Old 05-11-2019, 09:23 AM   #10
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Some progress...
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Old 05-12-2019, 07:15 AM   #11
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A member named Red Devil had success (kinda) supercharging his Subie a generation ago. That guy had a ton of energy and just plan when for it.
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Old 05-12-2019, 05:47 PM   #12
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If I'm reading that compressor map right, you're going to be close to compressor surge. I'm not saying it won't work, but I think it would be a good idea to plot the actual pressure ratio and mass flow as soon as you start data logging, just to be sure you're on the right side of that line.

With a pressure ratio of 2.5:1 my stock EJ25 only flowed about 40-45 lb/min with a Garrett GT3076. That's not an apples-to-apples comparison but it's something to think about.

And I have to confess I'm not clear about what "corrected" mass flow means on that map. Maybe the underlying actual mass flow is different enough to make this concern go away.
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Old 05-13-2019, 06:36 AM   #13
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Default Vortech supercharger for ~500whp? Si Too big?

Guessing corrected it is just corrected for standard atmospheric conditions but I donít know for sure. Iím starting with a 3.125Ē pulley and I think itíll be about 1.8 PR and flow 40 lb a minute @6400 rpm. We will see how it goes from there, itíd be just barely not surging but should be good enough.

One thing I failed to consider is that belt slip may be an issue that canít be overcome realistically (without a custom cogged crank pulley ) at some point. I donít really want to deal with that, at least not now, so I will stop whenever it canít hold the power with good pulley wrap and grip treated pulleys.

Last edited by pcampbell; 05-14-2019 at 06:41 AM.
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Old 05-17-2019, 08:48 PM   #14
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some more progress. Very close to a first drive.
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Old 05-23-2019, 06:38 AM   #15
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Itís running now. However itís only at 8psi lol. Just ordered a new pulley.

For 2 days I thought it was belt slipping then finally realized the pulley is just what it is. Itís gripping and is good for 8psi. The MAf reading around 200-210 so it All makes sense. I got a little ambitious and the next pulley might be too wild.

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Old 05-23-2019, 06:39 AM   #16
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One more pic. Lots of clean up to do but itís solid.
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Old 05-23-2019, 06:42 AM   #17
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Default Vortech supercharger for ~500whp? Si Too big?

I donít see this putting out 500 anything though. Which is fine. I had a 3.125 pulley on there and am going to 2.62Ē and will likely not venture smaller than that.

Last edited by pcampbell; 05-23-2019 at 09:11 AM.
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Old 05-23-2019, 09:39 AM   #18
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Looks good.

Hood closes fine? How's it sound? Keep the updates coming.
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Old 05-23-2019, 12:56 PM   #19
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Yeah hood closes fine, the only funny thing is the hood prop comes within like 1/4" of the SC pulley when the hood prop is in the resting position haha. I may have to raise that up another 1/4" for sanity. I am working on cleaning it up a bit.. the BPV setup in particular is awfully ugly.
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Old 05-24-2019, 10:10 AM   #20
pcampbell
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Default Vortech supercharger for ~500whp? Si Too big?

Quote:
Originally Posted by TDagen View Post
Looks good.

Hood closes fine? Howís it sound? Keep the updates coming.


It sounds pretty mean, with very unequal length headers and a 2.5Ē mandrel catback. It has 2 (in a row) magnaflow mufflers and is still pretty rowdy.


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Old 05-24-2019, 01:42 PM   #21
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That does sound mean, prob sounds meaner cruising around too.
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Old 05-24-2019, 07:14 PM   #22
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Only real issue with a blower....is I'd have concerns about the longevity of the crank snout.

It's pretty small on a Subaru, and the nature of the crank design with the thin webs between journals really wouldnt lend itself well to a lot of load, or worse, side loading on the snout.
Plus the pulley really has very little engagement onto the nose.

If staying small, and a setup that doesnt need a lot of belt tension it might be ok though. But it'd worry me.
Make sure you use a good spring tensioner setup for the drive pulley, so you can avoid having to heavily tension a manual tensioner.
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Old 05-25-2019, 06:44 AM   #23
pcampbell
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That is a good point. I hadnít thought that much about pressure on the crank. I will settle in something that doesnít require too much belt tension. If you have to crank it down too much the it just stretches the belt and you keep tightening it and repeating and it is very annoying haha.
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Old 05-25-2019, 06:58 AM   #24
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Quote:
Originally Posted by pcampbell View Post
That is a good point. I hadnít thought that much about pressure on the crank. I will settle in something that doesnít require too much belt tension. If you have to crank it down too much the it just stretches the belt and you keep tightening it and repeating and it is very annoying haha.

The problem with a manual tensioner...is you pre-tension the belt to grip...but also to combat belt stretch under load. So it's a double fail really....you're overloading to start with, but once the belt has stretched beyond the point where it can grip....that fixed tensioner can never apply more tension to help it grip.

Whereas with a good spring tensioner, it can apply a good constant tension when not under load...but also allow for some belt stretch whilst still maintaining some tension. But hopefully you would never need...or be able to over tension it.

Again, on lower power setups maybe less of an issue, or with large pulleys etc where they will have more wrap to help grip....or with wider belts etc.
But the underlying problems are there, as are the fact they still require a fair load from the crank to drive them

The Sub front pulley is pretty small diameter, so no huge wrap or grip there ( but should be adequate ok ) It also only engages on the snout a pretty small amount...so no huge drive strength there either.

But compared to a typical V8 or most engines...the crank webs on a Subaru would be very thin and not ideal for a big side loading out front.

But 4-500hp if you can get it, with instant throttle response and all the extra torque even a smallish centri will offer....is bound to feel fantastic in the car compared to any turbo.

Ideal candidate for a big turbo....blow it directly into the mouth of the Vortech. No lag, lots of power.
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Old 05-25-2019, 12:59 PM   #25
pcampbell
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Default Vortech supercharger for ~500whp? Si Too big?

Thanks for your feedback. Yeah the crank is very small. 5.25Ē roughly. I have a carbinited (grip treatment) crank pulley sitting here not installed yet.

Also have drilled holes in the SC bracket to add more idlers for the crank pulley wrap but not currently using them.

I will have to see if thereís some way to get a spring tensioner into this setup. Iíve looked at the dayco ďno slackĒ ones. May be able to sneak this in to the top/right of the supercharger in place of the fixed idler. I need to figure out which way they tension.

https://shop.advanceautoparts.com/p/...iABEgLMp_D_BwE


Last edited by pcampbell; 05-25-2019 at 01:04 PM.
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