supercharger manidolds

[FCRB26]

Done and dusted moded pipe again

and hpc coated

[Old_Mt_Isa_Boy]

That's a work of art Pete not a supercharger manifold.


Regards

Wayne b

[FCRB26]

Were running a S/S turnbuckle off the bottom of the manifold down to the engine mount for extra strength.
catch can to do next then 1 piece his bumpers and im done.
Back onto my own stuff

[FCV08]

Pete

I agree with Wayne. 

That is a fine piece of workmanship.

Regards

Craig D

[FCRB26]

Hopefully this god damm eh is done bye this week.
 my mate dan is taking her to summernats just needs gas mixer fitted.

[Ol_Girl_58]

That's a tidy wagon. Neat fab job too.

I gotta say though - these Showwheels are like ROH Reflexes of the 90's/Hotwires of the (late)70's/(early)80's. No disrespect intended - more of a personal observation.

Cheers,

Josh

[FCRB26]

None taken \
I prefer them over 5 spoke dragways but maybe a bit small rolling diameter tho.



Pete

[FCRB26]

Learnt some valuable lessons about supercharging now pumping 6psi
Had been running sweet for months summernats had tons of enquiries but hadnt had enough of a run for me to be confident with it.

Well it backfired the other day with a very very loud bang blew the manifold to pieces.
Blew the teflon off the rotors.
3 explosions in 3 weeks

So im fitting a 8psi blow off valve to the bottom to vent it any ideas fellas ?

[Glenn 'Stinky' Stankevicius]

No BoV? 

[collecta]

 Pete it looks like a typical lpg backfire. I've seen plenty of air boxes blown to pieces just from a lpg backfire that have not been fitted with some type of blow out device whether it be a kitchen sink plug with a spring or trapdoor spring loaded. As you said had been running fine up until then.

Scott

[FCRB26]

Im mounting a BOV under the manifold tommorow as per my mates request but i said to him your venting LPG onto the exhaust side you sure you want to do that.

I reckon a plumb back BOV into the intake maybe?

[Harv]

She's a blow-through set up (like the Normans), so you end up with a lot of volume full of air/fuel mix... add a burp through a passing valve (or high valve overlap) and you bang the blower. The bigger the plenum (... or add an intercooler) and they get worse (Eldred used the word "nuclear"  ).

I would not recommend a "blow off valve" for this. The are generally made to stop surge in centrifugal turbos when the throttle plate shuts... and not for relieving the sudden, hot and heavy pressure from detonating air/fuel. Not likely the BOV would last long. It would then start to pass - letting loose an air/fuel mix into the engine bay on the sly. Whilst you can plumb a BOV back into the inlet manifold, it is useless in this case... it just transfers that explosive pressure back into the carb/mixer, blowing of the air filters. Many BOV's are also set up to sense vacuum before they open (throttle plate shut, engine sucking madly on it, tapping downstream, high vacuum, open BOV, vent that compressor that is spinning madly up against the shut throttle plate). What you would be looking for is a BOV that opens under high (...explosive) pressure rather than vacuum - finding one could be hard.

You could use an industrial relief valve ... but they don't look right. I've also seen aircraft cabin pressure control valves used, though finding one is like rocking-horse poo.

A better (and dead simple) option is a relief valve plate - either make your own, or buy one to weld/bolt on from Weiand (part number 7155 for the smaller one or a larger size available as part number 7158),  The Blower Shop (part number 2589) or Aussie Speed ("universal back fire valve"). I've got dimensions for the typical home made triangular Norman one if you want to make one.

I've got a fairly good write up on this with photos, dimensions, spring settings etc. I'm aiming to post it around next weekend in Harv's Norman Supercharger Thread... if you need the info earlier, PM me an email address and I'll PDF it up and mail it back.

Cheers,
Harv (deputy apprentice Norman supercharger fiddler).

[FCRB26]

I was hoping you jumped in thanks for the info.

I spoke to tony webster from webbys speed shop he said they use to use a valve and a valve spring mounted into a alloy block and weld that onto the blower but like he said your venting pure gas into the engine bay ?

.


Pete

[Harv]

Yep, the older type set ups were a flat plate and valve spring. The newer ones are no different... just fancier plates. On the big-boy setups (GM blowers) they often use a burst panel instead. Pain in the arse changing a burst panel in a Woolies car park on a street car though, hence the plate/spring setup.

The pop-off valve should only lift when there is a detonation in the inlet manifold. It lets out a half burnt sneeze of ignited fuel/air. Not the best of things under a bonnet, but not the end of the world. Little worse than a carb backfiring (my daughter still laughs about the last time I lost my eyebrows to a sneezing Holley). Remember that this should happen only every now and then, not every time you back off the throttle (this is not a ppsssshhhhht blowoff valve). If the motor has horrific valve overlap and is banging the blower constantly, then consider an industrial relief valve (eg Crosley) plumbed down like a grey motor walking stick.

I'll pdf the info I have and email it through shortly.

Cheers,
Harv

[FCRB26]

Thanks very much harv.

I spoke to webby about it for 2hrs and he said he had seen a lot of set ups over the years ect gas is the worst alchahol is the best.

How does a stock supercharged commodore get rid of the gas if this happens ? also i noticed on a friends pure gas falcon it has a relief built into the air box..

pete

[Harv]

No drama - you got email  . If you want some photos of the triangular Norman setup, give me a yell (I'm on the road for work shortly though).

Late model vehicles like the blown V6 Conformadores are a different set-up. The are generally run "blow through", where the fuel is added downstream of the blower (way, way downstream... almost at the cylinder head). This means that you don't have the big volume of air/fuel mix that is seen in suck-through superchargers like yours and the Normans. As there is not much there to explode, they often don't run a pop-off valve or burst plate.

Late model blown vehicles are also more likely to be centrifugally supercharged. Because they are not positive displacement blowers, they don't get upset (as much) if the inlet manifold farts (they just slip a bit internally)... whereas a positive displacement blower (like the Norman or a 6/71) will stall the blower, snapping seals and potentially bending the rotors. A positive displacement blower hooked up via a toothed gilmer drive can even transfer that stall all the way to the crank... ouch  . This is the reason that (unless you are chasing every ounce of grunt) it is not a bad idea to run vee-belts rather than gilmer drives on positive displacement huffers.

Cheers,
Harv

[FCRB26]

Photo shoot last night EH ran awesome


Then KABLAMMO massive bang with a nice blow off flutter absaloutley smashed it to pieces this time its buggered now.

so i got some valves out of a cat dump truck engine and am making a blast vent just need to get spring pressures right..

[NES304]

Cool pic!