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Old 06-22-2020, 02:57 PM   #176
junebugfareast
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Quote:
Originally Posted by rtv900 View Post

Wrong.
It's impossible unless you have a physical compressor, which a turbo is not but a PD roots type is. Nobody is pretending you can maintain pressure in an open pipe, obviously that is ridiculous, but it would discharge at pressure no different than a piston compressor pushing up into it's chamber and then the valve opens and blows out physically compressed air.
A turbo will never do that, it is just a fan, it only moves air, it doesn't compress it.
A centrifugal compressor simply won't work unless it is compressing the air moving through it. The flow will surge and destroy the machine.





A roots blower can go all day long into an open discharge. As you note, the size of the downstream system is what determines the boost pressure (355 SBC might get 15 psi of boost at 1/1 drive with a 6-71 and a 572 BBC might not even get into positive pressure).
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Old 06-22-2020, 05:12 PM   #177
rtv900
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Quote:
Originally Posted by junebugfareast View Post
A centrifugal compressor simply won't work unless it is compressing the air moving through it. The flow will surge and destroy the machine.

A roots blower can go all day long into an open discharge. As you note, the size of the downstream system is what determines the boost pressure (355 SBC might get 15 psi of boost at 1/1 drive with a 6-71 and a 572 BBC might not even get into positive pressure).
No clue what you mean by that first statement, what won't work? It is a fan, that's it.
You are using the term surge totally out of context.

Agreed on the 2nd statement but that isn't the point. The downstream portion always controls total pressure no matter what you have. If you are drawing more from the same compressor of course it won't get up to the same amount no different than using a garage piston compressor that is too small to run a DA sander. It piddles along at 50 psi but if you get a bigger compressor it runs at 100 psi continuous.
Completely different issue.
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Old 07-18-2020, 07:58 AM   #178
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Default Vortech supercharger for ~500whp? Si Too big?

Question: if I go for inconel exhaust valves, super tech OE size are $45/valve and plus 1.5mm are $25/valve. The reason is that the +1.5mm are off the shelf. Stock size is custom.

Will it do any harm to go with the larger valves with a radius valve job? Ie will I loose power? Obviously Iíll pay a little more for machining on the larger valve.

I know there are some rules of thumb about valve lift to valve diameter but not sure if those apply to forced induction motors.
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Old 07-18-2020, 08:01 AM   #179
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I'd always prefer Ferrea.

Are you just changing valves, or actually getting proper headwork done too ?

If just valves, no reason at all to go larger.
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Old 07-18-2020, 03:31 PM   #180
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Default Vortech supercharger for ~500whp? Si Too big?

I donít know if Fererra makes sohc valves, maybe just a custom order thing? I was just planning on having a radius valve job done. No port and polish.

Last edited by pcampbell; 07-18-2020 at 03:37 PM.
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Old 07-18-2020, 05:11 PM   #181
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I'd just leave the Subaru valves in then. In terms of quality, they're hard to beat.
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Old 07-19-2020, 07:59 AM   #182
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Default Vortech supercharger for ~500whp? Si Too big?

Do you think stock Subaru NA exhaust valves can take the heat?

Not sure if Na construction is much different than the turbo valves.
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Old 07-19-2020, 09:49 AM   #183
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you aren't turbocharged, there wont be the same heat to deal with.

And aftermarket valves are not sodium filled either.

Has there been some sort of issue with the current valves ?
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Old 07-19-2020, 07:21 PM   #184
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Default Vortech supercharger for ~500whp? Si Too big?

Only that they are 207k miles old. Leakdown test shows a little exhaust valve leakage. I donít know how much of that is related to age versus heat from boost. Probably a combination. Definitely using stock valves is the cheapest option. I have a spare set which are newer and look to be in good shape.
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Old 07-29-2020, 04:36 PM   #185
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This is pretty cool - bone stock EJ251 heads , 400whp on a 20g on E85 and 22psi. This is an open deck EJ251 too, although the rods and pistons are not stock.

https://www.facebook.com/groups/4912...1619073532641/

I suspect very close power should be possible with similar boost on the supercharger and Delta 1500s, if I ever get my new crank pulley!

Anyone seen a supercharged Subaru more than 500whp?
https://www.lasleeve.com/tech/laslee...0whp-brz-build

Last edited by pcampbell; 07-29-2020 at 04:55 PM.
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Old 07-29-2020, 06:46 PM   #186
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Certainly a money no object build there, very nice.
Although odd they say they cant find a transmission to use, Samsonas have done their sequential for the BRZ for several years which would easily handle what they have and a lot more, or they also offer an H pattern dog box.

And surprising how far they pushed boost on the high compression engine on just 91 octane, not often people in the US try much with pump fuel.
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Old 09-07-2020, 08:26 PM   #187
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Default Vortech supercharger for ~500whp? Si Too big?

Been waiting a while for my custom 8 rib Off the front SC pulley which is now in transit.

So here is a question , being that my SC setup doesnít make that much torque will 251 (basically ej205 rods) rods hold up to say 300 plus ft lb ? The only reason I ask is that JE forged pistons for 251 rods are quite reasonable. I can get a set of pistons for just over $500.

A 251 SHortblock with the JE forged 8.5:1 pistons, stock rods and ARP rod studs fully balanced just over $2000. Just an option.

Looks like k1 makes 131.5mm rods too, which can be had for under $300.

Last edited by pcampbell; 09-07-2020 at 09:42 PM.
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Old 10-29-2020, 08:48 PM   #188
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Still waiting for my custom 8" 8 rib pulley--5 months now, it is apparently "lost" or misplaced in shipping. I got impatient and ordered a 10 rib 7" vortech universal pulley, which seems to bolt up to an 917991 ATI Damper, nearly perfectly. It was a little tight,but once mounted it is fine, smooth, no wobble. I don't know if the B.C. is officially the same.





My goal will be to try to get it running on 8 ribs (10 ribs I am sure will run into my fans...) with a 3.12 supercharger pulley it'll run about 20psi at 6800rpm if the belt doesn't slip. This is about 2 psi more than I've ever seen at the same rpm, but what I had wasn't really able to be reproduced due to belt slip.
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Old 11-04-2020, 07:24 AM   #189
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Does anyone know if mishimoto or something other low profile fan and shroud kit will fit an 2005 Outback? Iíve heard the mishi one for sti may fit ? I might need some room for my belt.


https://www.mishimoto.com/subaru-wrx...kit-08-14.html
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Old 11-04-2020, 03:07 PM   #190
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Spal make a wide range of sizes of fans, pick one ( or two ) that suits. A good shroud is certainly a benefit, although not always essential.
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Old 11-11-2020, 08:39 AM   #191
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Thanks.

Not making much progress lately. My experience with this pulley maker has sucked my enthusiasm away. Paid a lot of money for a custom 8Ē 8 rib pulley 6 months ago and have nothing to show for it still.
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Old 11-20-2020, 07:31 AM   #192
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Default Vortech supercharger for ~500whp? Si Too big?



Pretty ghetto looking right now but I think itíll do the job (obviously it is not fully bolted up yet here ). It is an ICT billet LS tensioner mounted upside down and backwards too.

New Vortech supercharger side pulley arrives today. I opted for sizing it to hit 55k impeller Rpm at 6450 rpm which is roughly 20psi if not slipping.

Then I just need a new idler the correct width on the tensioner and a correct belt size to run the 8 rib setup.

Random thought : Iíve been driving around without the SC hooked up (plumbed but no belt) for a few miles and the engjne drone is significantly LESS bad than WITH the SC even under vacuum/cruise. Any sense to be made there? Just less airflow? Could it have anything to do with BPV size ?

Last edited by pcampbell; 11-20-2020 at 07:38 AM.
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Old 11-20-2020, 03:27 PM   #193
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Quote:
Originally Posted by pcampbell View Post
Thanks.

Not making much progress lately. My experience with this pulley maker has sucked my enthusiasm away. Paid a lot of money for a custom 8Ē 8 rib pulley 6 months ago and have nothing to show for it still.
what did this pulley cost?
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Old 11-20-2020, 04:49 PM   #194
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Default Vortech supercharger for ~500whp? Si Too big?

The custom pulley was $465. As of right now , itís supposedly getting reshipped after being lost for 3 months with fedex.

The pulley I ended up putting on was $168 with tax. It is an off the shelf Vortech part 4ma018-51.

The custom one is probably better because itís 1Ē bigger which means in turn using a bigger supercharger pulley which altogether means less belt slip but obviously there is a big difference in price.

I had no idea these off the shelf pulleys would bolt up when I ordered the custom one because it is really hard to get info on the bolt hole spacing on pulleys from ATI and Vortech. Fluidamper sent me whatever technical diagrams I asked for very quickly.
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Old 11-20-2020, 05:01 PM   #195
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sheesh $465 for a pulley, that sounds pretty steep even for something custom

For one, doesn't it just bolt through the center hole? What hole spacing are you talking about?
Also, in that pic just above the pulley on the drive of your supercharger doesn't look anywhere near 8"
And, doesn't the change in 1" of diameter totally change your rotating speed on the supercharger and completely change how it will work?
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Old 11-20-2020, 05:34 PM   #196
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Default Vortech supercharger for ~500whp? Si Too big?

Quote:
Originally Posted by rtv900 View Post
sheesh $465 for a pulley, that sounds pretty steep even for something custom

For one, doesn't it just bolt through the center hole? What hole spacing are you talking about?
Also, in that pic just above the pulley on the drive of your supercharger doesn't look anywhere near 8"
And, doesn't the change in 1" of diameter totally change your rotating speed on the supercharger and completely change how it will work?
This one is 7" which is this:
https://vortechsuperchargers.com/pro...ant=7811169985



The bolt spacing in question is the bolt spacing of the threaded holes on the face of either an ATI super dapmer or Fluidamper. I am pretty sure both ATI and Fluidamper are 2.8" B.C. now. The stock crankshaft pulley is not really compatible with a bolt on supercharger pulley, but aftermarket ones have threaded bolt holes on the face.

Yeah you would change the supercharger side pulley to match the crank pulley to get the boost or impeller speed you want at the RPM you want .

So if I ran a 8" crank pulley, I'd run a 3.12" or 3.33" Supercharger pulley.
With the 7" crank pulley I'm running a 2.95" to get hopefully somewhere like 20psi around 6450 or so rpm. You have to change belt sizes too. The tensioner will only take up so much slack.

In general I think bigger is better as long as it fits.

Last edited by pcampbell; 11-21-2020 at 06:34 AM.
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Old 11-21-2020, 12:54 AM   #197
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Looking really cool dude. Keep up the good work. Sorry about the pully issues
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Old 11-27-2020, 04:31 PM   #198
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Here it is running with the 8 rib setup.

It needs a bigger idler on the tensioner, which I have on hand (barely clearing the radiator hose and not quite enough tension) but it does run and belt seems to line up well. Needs a lot of tuning and a little tinkering.

I figured that I need to move the tensioner over like 1/4" or so to fit the larger tensioner idler pulley correctly. The tensioner pulley needs to be able to swing all the way up and clear the SC pulley to work well.

I did a quick test in the rain here, hit 18.5 psi @ 6250rpm , 393g/s (probably not quite true g/s because AFR is a bit rich compared to target AFR) with what I think now is the belt spinning (as opposed to tires or clutch). Fixing the idler will give me better belt tension so I think there is quite a bit more, not to mention I can rev it out a little more.


Last edited by pcampbell; 11-27-2020 at 06:14 PM.
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Old 11-27-2020, 08:07 PM   #199
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Default Vortech supercharger for ~500whp? Si Too big?



Tensioner Idler to SC pulley. They must clear each other for the tensioner to really work right. Here they do but bigger one doesnít yet.
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Old 11-28-2020, 07:13 AM   #200
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Re-drill a new hole and move it a little.
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