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Discussion Starter · #1 ·
Anyone have first hand and/or constructive information with regard to high boost limitation proportional to a 'potential' catastrophic failure rate on a TVS-1900 PN: 12670278 supercharger setup. I have done a few 15-17 lb short pulls in a verified optimum condition non-ported, upper/lower pulleyed, ZL1 lid setup.
Thank you ;)
 

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Anyone have first hand and/or constructive information with regard to high boost limitation proportional to a 'potential' catastrophic failure rate on a TVS-1900 PN: 12670278 supercharger setup. I have done a few 15-17 lb short pulls in a verified optimum condition non-ported, upper/lower pulleyed, ZL1 lid setup.
Thank you ;)
Can you explain “verified optimum condition non-ported…”

If you do your due diligence, have adequate cooling and octane, and a good tuner, you can be confident of it living.

Actually, I take that back, too many variables like driver, owner, maintenance, oil, parts selection, etc.


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Anyone have first hand and/or constructive information with regard to high boost limitation proportional to a 'potential' catastrophic failure rate on a TVS-1900 PN: 12670278 supercharger setup. I have done a few 15-17 lb short pulls in a verified optimum condition non-ported, upper/lower pulleyed, ZL1 lid setup.
Thank you ;)
How fast is the blower spinning?
 

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Discussion Starter · #4 ·
at about engine 5600rpm 110mph

How fast is the blower spinning?
5600rpm 110mph

Can you explain “verified optimum condition non-ported…”

If you do your due diligence, have adequate cooling and octane, and a good tuner, you can be confident of it living.

Actually, I take that back, too many variables like driver, owner, maintenance, oil, parts selection, etc.


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I built and am tuning it myself. I sent the supercharger out and had it professionally certified 'excellent' prior to install, had 10k miles on it prior to inspection and service. Excellent cooling system, charger oil new and level.
 

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check how many times the blower pulley turns per crank revolution, then multiply your peak engine rpm by that ratio gives u blower speed
 

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Try this:


Enter your pulley sizes and RPM it will give you the blower RPM.
 
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Discussion Starter · #8 · (Edited)
Try this:


Enter your pulley sizes and RPM it will give you the blower RPM.
Engine @ 6500rpm is 23400 SC speed with my current pulley combo, stock is 16900 at the same rpm. My question is, what limitation can I realistically expect before potential issue? Basically I have already increased the stock setup 40%, boost cut and solenoid disabled, so there are no limits, just want to know if there is a threshold based on others experience?
 

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I'm sure others will chime in but I personally wouldn't feel comfortable pushing the needle to the red too much. It also depends on how much you beat on it and what cooling mods you've made to keep IAT2 (MAT) temps in check. I am not as well off as most on this forum and couldn't afford a catastrophic failure.
 

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Calculating blower speed is super easy, you don’t need a chart nor a calculator.

Lower pulley diameter divided by upper pulley diameter, that gives you the ratio, multiplied by engine rpm.

It even works for metric dimensions, just for our Canadian members.


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23K isn't pushing it that hard if the rebuild was done properly
And how many times a day the blower sees that rpm. . . .

Cheers
 
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23K isn't pushing it that hard if the rebuild was done properly
Matt,
This post is not aimed at you, I am simply tying into your 23K rpm value.

While we both know some are spinning their blowers higher than that for a 'Race Prepped' application, maybe the OP should consider the following. . . .

---------------------------------------------------------------------

A 1.9L blower has an internal volume of 115.9 CID.

What would be the cfm output of said blower at stated rpm. . .
=> (23000 * 115.9 / 1728)= 1,543 cfm.

If the 1543 cfm was as about 70°F, the engine would be capable of producing. . .
=> (1543 / 1.5)- 1,028 fwHP. But the temperature exiting the blower is much hotter than 70°F.

With a good 'Mass Flow' recovery system, these engines will typically produce fwHP proportional to about 70% to 75% of of the cfm output from the blower. So then; that would amount to about 724 fwHP to 775 fwHP.
***Is the OP understanding that he is attempting to produce those HP numbers, using that pulley ratio?

That HP number represents about 100% cylinder fill.
That is a good number for such a small roots style blower using gasoline(JMHO)!

-when using the 1.9L Roots Blower-
At or around 100% cylinder fill, most 'Must' move on to an oxygenated fuel, such as E85, which is worth about 75 rwHP to about 100 rwHP, now moving one into the +800 rwHP range.

It is my opinion that a daily driver will require more blower maintenance when spun to ~23k to 24k rpm's, because one is attempting to produce an engine that can fill the cylinders to ~100%, then one that is spun to a lesser rpm.

Possibly the OP should consider a pulley ratio that would yield ~660 rwHP and then consider moving over to using E85 for fuel in an attempt to find that ~750 rwHP number.

Finally to the OP: might you consider putting your engine build / modifications into your signature line so that when you pose a question, all of the pertinent info is readily available..:)

Cheers
 
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Discussion Starter · #14 ·
Matt,
This post is not aimed at you, I am simply tying into your 23K rpm value.

While we both know some are spinning their blowers higher than that for a 'Race Prepped' application, maybe the OP should consider the following. . . .

---------------------------------------------------------------------

A 1.9L blower has an internal volume of 115.9 CID.

What would be the cfm output of said blower at stated rpm. . .
=> (23000 * 115.9 / 1728)= 1,543 cfm.

If the 1543 cfm was as about 70°F, the engine would be capable of producing. . .
=> (1543 / 1.5)- 1,028 fwHP. But the temperature exiting the blower is much hotter than 70°F.

With a good 'Mass Flow' recovery system, these engines will typically produce fwHP proportional to about 70% to 75% of of the cfm output from the blower. So then; that would amount to about 724 fwHP to 775 fwHP.
***Is the OP understanding that he is attempting to produce those HP numbers, using that pulley ratio?

That HP number represents about 100% cylinder fill.
That is a good number for such a small roots style blower using gasoline(JMHO)!

-when using the 1.9L Roots Blower-
At or around 100% cylinder fill, most 'Must' move on to an oxygenated fuel, such as E85, which is worth about 75 rwHP to about 100 rwHP, now moving one into the +800 rwHP range.

It is my opinion that a daily driver will require more blower maintenance when spun to ~23k to 24k rpm's, because one is attempting to produce an engine that can fill the cylinders to ~100%, then one that is spun to a lesser rpm.

Possibly the OP should consider a pulley ratio that would yield ~660 rwHP and then consider moving over to using E85 for fuel in an attempt to find that ~750 rwHP number.

Finally to the OP: might you consider putting your engine build / modifications into your signature line so that when you pose a question, all of the pertinent info is readily available..:)

Cheers
Thank you for all the info, good advise to post some basic info about my build, I'll take care of that. I'm not concerned at all with the engine side of my build with regard to stress, I just don't have much in the way of feed back based on others experience with overdrive on the supercharger. Thanks again...
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Engine @ 6500rpm is 23400 SC speed with my current pulley combo, stock is 16900 at the same rpm. My question is, what limitation can I realistically expect before potential issue? Basically I have already increased the stock setup 40%, boost cut and solenoid disabled, so there are no limits, just want to know if there is a threshold based on others experience?

As others have said. It's not about boost numbers for a blower issue. It's the RPM too much boost and you will have bigger issue than a bower rebuild. The rule has been try not to go over 23k for it to live, but this is open ended. How often will the blower see that max RPM. Also you shouldn't disable boost protection completely on a street car. There are reasons you do want it to dump boost for engine safety.
 

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a 2.5 / 9.1 lower ratio seems pretty common, with plenty of "daily driver" types going to a 2.5 / 9.5, and I believe I ran a 3.0 / 10.5 ratio for many years on my daily, which saw 15+ psi and 6800 RPM on mostly a daily basis. That's 24k RPM, and my blower of course was ported and rebuilt by Jokerz.

I think a general rule based on our years of modding here on the forum, is to keep a "3.5x blower ratio" as a good overall combination for longevity and maximizing power with the 1.9L on a street car. Of course a daily driver won't get wound up quite as often relative to the overall life of the blower, nor will it generate as much sustained heat from a single pull relative to a racing car that sees sustained heat - and those are important considerations. Certainly, for sustained, high RPM use of the blower I would want to be substantially LOWER in ratio specifically due to heat generation in the bearings and IAT2s.
 

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Discussion Starter · #18 · (Edited)
Sounds like some reasonable experienced feedback. I do realize the difficulty providing a definitive answer on a subject question such as this, especially when there are so many other variables to consider. I suppose in the absence of catastrophic failure experiences shared on this site, it is a rarity that this model charger has a know history to be overly concerned about.

In addition to my original question, I would also like to ask, since it was brought up, how common is it for members on this site to tune-out boost modulation and cut? My usage will be occasional street WOT mode, not planning to track too often any longer in the future.

One last question, any charger oil servicing schedule you guys follow as a general rule? ty
 

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You nailed it. The sustained boost puts a lot of heat into the blower, and aluminum expands quite a bit when heated, and faster than ferrous metals.


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Sustained heat is also what causes the aluminum block to stop supporting the cast cylinder liners, as the two expand at different / varying rates versus time.
 
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My blower bearings went very bad within 3k miles after pulley change from stock and drag racing 10 times. I was hard on the car under normal driving also...can't seem to keep from WOT. I was spinning 23400 on 16lbs boost. My tuner has done lots of GM super charger builds and was surprised. Said it was a rare occurrence.
 
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