Rotrex vs Turbo (AVO) for Track use (transient response, IATs, heat management, etc)

[CSG Mike]

The compressor may be more efficient, but at what point in the RPM band?

[FreshFRS]

Originally Posted by sw20kosh

So a rotrex supercharger (of some size) on this engine theoretically can produce >340 whp at 11 psi on 93 octane? I had no idea they were so efficient?

i doubt even the C38-91 spun at 11psi would make that much power. but i guess you'd have to run it and find out, from my estimation you'd only be spinning the blower around 65krpm. max is 90.

Theoretically the airflow would be similar (looking at both compressor maps) to a gt30r but i doubt it would make the same power. thats just my assumption though.

[gmsii]

Originally Posted by Sonolin

Also...

With that torque curve?

Saying superchargers are *more efficient* than turbochargers is stupid... Yes the IAT will be lower but that doesn't mean its more efficient in terms of a power adder. Its a trade off, either way.

Yet another reason *not* to buy KW.

who said superchargers are more efficient?...when we talk about efficiencies we are talking about compressor maps....comparatively speaking the rotrex and turbos (with comparably sized impellers and compressor housings) have compressor maps that are similar...differences in efficiencies would boil down to impeller wheel and compressor housing design.

if you read what i wrote, i said the rotrex is going have lower temps which will make more power, but the trade off was that it would also take a few hp to turn the supercharger.

[gmsii]

Originally Posted by glamcem

Thanks for the explanations. I guess I am leaning towards to KW kit but can you please tell me whether or not I can use the SUBARU oem oil cooler with a smaller nut (the one behind the idler pulley)? The bracket size is my only concern with your kit, other than that it looks very good. I know you guys will soon offer an oil cooler kit as well but I would like to use the OEM cooler for OEMish look, simplicity and cost.

shouldnt be a problem using that cooler

[glamcem]

Originally Posted by gmsii

shouldnt be a problem using that cooler

That's what I figured, worst case scenario I think I can use a slightly smaller nut/bolt with a lock washer.
Thanks

[kiichiro]

Originally Posted by Sportsguy83

The fitment was TIGHT, needed to hack a little here and there, but the end result is just incredible.

There is nothing I can throw at it to make it get hot... Back to back to back pulls, back to back to back 1/4 runs, I haven't tracked it in a road course, yes, but I've done about everything but... 5 back to back to back dyno pulls, 35 in 3 hours, nothing gets it uncomfortable.

Road course is the Real litmus test

[Sportsguy83]

Originally Posted by kiichiro

Road course is the Real litmus test

Agree. Already been done by others, limit has yet to be found

[philooo]

I am curious to hear more forced induction track guys.

What's the verdict on the most reliable/cool kit for road course endurance ?

I think a modest amount of additional power is ok if it can be sustained.

[glamcem]

Originally Posted by philooo

I am curious to hear more forced induction track guys.

What's the verdict on the most reliable/cool kit for road course endurance ?

I think a modest amount of additional power is ok if it can be sustained.

I have been tracking my Kraftwerks powered BRZ for a while and happy so far, I have been pushing really hard too.. I snapped my belt at the last event but since it's a separate belt design I was able to drive with no problem.. hopefully I will get my replacement belt soon and will attend a few more events before October

[philooo]

@glamcem, did you had any trouble keeping it cool ? or the combo radiator and oil cooler did the trick for you since day one ?

What's your take on the difference between the supercharger in the market: Vortech / JacksonRacing / Kraftwerks ?

[CSG David]

Originally Posted by philooo

I am curious to hear more forced induction track guys.

What's the verdict on the most reliable/cool kit for road course endurance ?

I think a modest amount of additional power is ok if it can be sustained.

I can't comment on Kraftwerks kits since there are none on track in Southern California that I know of, to test and collect data for. Jackson Racing, Vortech, and Innovate kits are abundant on track and are the only FI kits that are CARB legal right now. Vortech and Innovate had belt issues early on, but very few occurrences are found now due to proper revision of the system. JR has had no track failures thus far since its release. There was one occurrence in which the Rotrex SC blower failed, but Rotrex deemed it a manufacturing issue and has issued a warrantied blower free of charge.

For any FI system, you will need an engine oil cooler. Jackson Racing provides the one of the largest (if not largest), by volume, plug-and-play oil cooler kit on the market which has shown to maintain oil temperatures to a good level. Radiators are not absolutely necessary with SC, but fans are recommended with SC. With the Jackson Racing SC kit + Oil Cooler kit, we have found that the system maintains power even with 16 consecutive pulls on the dyno with the dyno fans on, hood closed, zero cooldown, zero ramping, etc. The back-to-back pulls without the oil cooler kit showed massive drops in power with each pull. The turbo setup showed significant power loss after 3 pulls (% same as 11 pulls on the SC w/o oil cooler) with good cooling setup.

The Vortech guys are using oil cooler kits + aftermarket radiators + our recommended fan setup to keep things cool. It also helps to have a good vented hood to help draw out the heat.

With any FI kit, the proper preventative measures should be taken. @King Tut has been able to provide information on how to develop a very reliable and powerful turbo setup. We have also made the Greddy Turbo Kit a success without overheating issues after some extensive cooling modifications. It's all in how much prep you put into the car as opposed to the absolute power gain you're looking for.

Hope all this information helps you out!

[philooo]

I wish all kit manufacturer would offer a road and a track version of their kits as obviously the road version really doesn't require that much cooling.

I am glad to see people here having good experience, so it seems to be doable at least

Does anybody knows here why nobody followed the TRD twin scroll supercharger design ? too expensive to build ? Because it seems that the solution all manufacturer are using, from GM in the z28, to Chrysler in their latest Hellcat engine.

[glamcem]

Originally Posted by philooo

@glamcem, did you had any trouble keeping it cool ? or the combo radiator and oil cooler did the trick for you since day one ?

What's your take on the difference between the supercharger in the market: Vortech / JacksonRacing / Kraftwerks ?

Since I live in NW I didn't really have heat issues with the OEM Forester oil cooler and KoyoRadiator combo except this one time when the ambient temps passed 95F degrees (that day I saw 270-280F few times ) other than that it typically stays between 250-260F on hot laps (which is pretty normal if you ask me, some may say the otherwise though) .. If I still lived in Florida I would definitely get the Kraftwerks' Oil cooler and still upgrade my radiator with a Koyo unit.. the main reason I wanted to get the OEM oil cooler instead of a stacked oil cooler(air to oil) is because the OEM unit can also be utilized the stabilize the oil temps for winter so it also works as an oil warmer.. and with the upgraded capacity of the radiator helps for recovery between cool down sessions..

After I read the horror stories of the Vortech units I would stay away from it ..maybe @Wonderbar can chime in and share his own experience with them..

It seems like for the extreme heat conditions JR and KW kits are better since they both utilize the same Rotrex unit ( there are some differences in detail and some prefer the other ) I would definitely read both of the threads of the owner experiences.. in my case being able to drive when a belt snaps is a big plus since I want to be able to drive home especially when I drive down to Oregon Raceway Park, also bigger IC on the KW might help for recovery too but by how much I don't know.. my experience with KW customer service is also great..good luck finding the kit that suits you the best..I think you can't go wrong with either Rotrex kit

[King Tut]

Originally Posted by philooo

Does anybody knows here why nobody followed the TRD twin scroll supercharger design ? too expensive to build ? Because it seems that the solution all manufacturer are using, from GM in the z28, to Chrysler in their latest Hellcat engine.

If you want a positive displacement blower, then go with the Innovate kit. What you will find though is that the blower is very small and will heat soak very quickly. The intercooler solution is too restrictive to make big power on 93 octane as well. The reason nobody followed the TRD supercharger was because it was expensive and only designed for racing teams, and they had no real success with it.