Max Boost With Stock Blower (Page 1/1)
rehoward JUN 13, 05:15 PM
I am wondering what the maximum boost is that the stock roots type blower can achieve reliably?
I have read articles where the stock diameter pulley is replaced with a smaller one to increase blower
RPM and hence boost, but I am wondering just how long a stock blower will last spinning faster than a
stock RPM? It seems like there must be a limit as to what speed and what maximum boost can be
achieved before the blower goes south.

I haven't read any discussion on this topic, all I have found so far is data on pulley diameter and the resultant
boost and engine horsepower. There must be a realistic limit on what the stock blower will survive.

Randy
rehoward JUN 13, 05:18 PM

quote
Originally posted by rehoward:

I am wondering what the maximum boost is that the stock roots type blower can achieve reliably?
I have read articles where the stock diameter pulley is replaced with a smaller one to increase blower
RPM and hence boost, but I am wondering just how long a stock blower will last spinning faster than a
stock RPM? It seems like there must be a limit as to what speed and what maximum boost can be
achieved before the blower goes south.

I haven't read any discussion on this topic, all I have found so far is data on pulley diameter and the resultant
boost and engine horsepower. There must be a realistic limit on what the stock blower will survive.

Randy



Oops, I meant to say the engine in question would be a transplanted supercharged 3800 from a Pontiac Grand Prix or similar.
Maybe this post needs to be moved to a different category?

Randy
Dennis LaGrua JUN 13, 07:03 PM
Max boost on a 3800SC will vary from the Eaton Gen III design to the Gen V design. I run the Gen V design 2003/2004- 3800SC with a 3.4" pulley and at WOT get 11 psi of boost. I would caution you about using that small a pulley without adding supporting mods like a 3" exhaust, 180* stat, Cooler Autolite 103 copper plugs and a SSIC. If you get KR's they can blow your engine. On the Gen III supercharger you will see lower boost and you might get by without the SSIC but the cooler the incoming air the higher the horsepower.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

rehoward JUN 15, 06:02 AM
Okay, I'll bite

What is SSIC and what are KR's?? Couldn't find those when I Googled.
olejoedad JUN 15, 08:52 AM
Short Stack InterCooler

Super chargers compress the incoming air. Whenever air is compressed it is heated. The SSIC is a water to air intercooler that cools the air.

Knock Retard

The Knock Sensors detect spark knock (pre spark detonation) and the PCM retards the ignition timing to prevent engine damage.
rehoward JUN 15, 01:47 PM
When you increase boost, will the factory knock sensors still be able to provide enough ignition retard to be effective
or will they need to be replaced with something else?

Is the air to water (engine coolant) heat exchanger deemed to be superior to an air to air intake cooler?

And again, does anyone know the max. RPM that a stock supercharger will withstand? There must be a physical
limit on this before the supercharger disintegrates.

As the supercharger pulley gets smaller the effective driving power it can transmit gets lower, possibly causing belt slippage.
Is there a larger crankshaft pulley available to help prevent this? That would of course mean that accessories would be driving
at a higher speed also which may not be too cool. I am not too familiar with this engine. Would it be possible to make the accessory
drive belt and the supercharger belt independent from one another using two different sized crankshaft pulleys?

Thanks,
Randy
olejoedad JUN 15, 02:44 PM
The supercharger belt is already separate from the accessory drive.
The super charger can live at very high rpm, driven by a pulley as small as 2.8 inches.
The OEM knock sensors are fine.
There is no air to air intercooler option, the water to air usually uses a methanol/water mixture and has a front mounted heat exchanger and pump setup.
If you want a lot of boost and power, ditch the supercharger and go with a turbo charger.

If you want even more power, go with an LS GM engine.
rehoward JUN 15, 04:20 PM
I see. So the water to air heat exchanger is a stand alone unit, sort of like a refrigeration unit
using water/alcohol as the wet side cooling media. Does anyone have a link to an example of this? I
assume it uses a fluid pump which is 12V driven? I honestly haven't heard of this before. What would
a good search term be for this?

[This message has been edited by rehoward (edited 06-15-2024).]

olejoedad JUN 15, 06:06 PM
ZZPerformance

Frozen Boost