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NA supercharger build


barneybrendan

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Not sure what the boost gauge is reading as Ian said the datalogging showd no boost at all,even up to 3000rpm.

 

It recorded -9psi at 1000rpm idle, which is what I'd expect - the engine will be breathing through the idle air control valve and the throttle butterfly will be pretty much sealed shut.

 

I did see a brief moment of positive pressure (1 to 3 psi) when the car first fired into life as you opened the throttle about 33% to get it going (no surprise considering how rich it is at the moment). So what you say about it constantly running boost is probably true. However the TB after the 'charger will still act as a big restriction at narrow throttle openings - the engine will still draw a vacuum as it's trying to metaphorically suck air through a small straw. I think it'll be quite sensitive to throttle inputs when tootling around, though - good luck reverse parking it :D

 

However at the moment I reckon you've still got electrical gremlins or fouled plugs. I'm hoping the latter, I'm thinking about the former. What could make the fuel pump and injectors suddenly work with a thump on the dashboard I do not know :blink: But it's having problems restarting now :(

 

-Ian

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Begining to think that the original idea of putting the throttle body first might actualy of been a better idea and a bit more tuner friendly.Instead of actualy mounting it directly on the charger like i was thinking i might try it half way up the intake pipe.I have another complete na intake system here to take parts off and flanges.Problem is this would set me back a couple of weeks but as i now have to wait for my bypass valve to come that might just be the time i need.

 

At the moment my plugs are black and soaking with fuel,so going to take them all out and give them a damn good clean.

I have got a delimiter,not sure where as it was already fitted when i got the car.

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There is an often-overlooked advantage which supercharging can provide - preheating of the air charge in off-boost conditions to obtain significant emission and economy benefits during warm up and cruise. It is fortuitous that this takes place automatically because the losses from pumping against a vacuum appear as heat in a smaller volume of air which therefore becomes much hotter. Even a screw compressor can deliver air at around 150 C when off-boost.

 

However, the effect does need to be controlled by some sort of by-pass or the pumping losses within the supercharger can outweigh the gains. Another drawback is that when the throttle is suddenly opened after a short period at light throttle the boosted charge is initially heated up as it extracts the latent heat that has built up in the system. This can give rise to a brief period of detonation - usually harmless but still undesirable. The same effect explains why supercharged engines often require minimal temporary fuel enrichment as the throttle is opened.

 

 

 

For highly boosted engines it can be better, not only to employ a bypass system, but also to place the throttle after the supercharger so there is no heat build up off-boost. A throttled supercharger on a racing engine, in the light load, high revving, condition during the seconds before the start of a race, can heat up nearly to the point of seizure, so as the car gets off the line both the blower and the engine (as the excess heat dissipates into the system) are under extreme stresses that do not apply at other times. Reliability is much improved with a bypass and throttling after the supercharger.

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There is an often-overlooked advantage which supercharging can provide - preheating of the air charge in off-boost conditions to obtain significant emission and economy benefits during warm up and cruise. It is fortuitous that this takes place automatically because the losses from pumping against a vacuum appear as heat in a smaller volume of air which therefore becomes much hotter. Even a screw compressor can deliver air at around 150 C when off-boost.

 

However, the effect does need to be controlled by some sort of by-pass or the pumping losses within the supercharger can outweigh the gains. Another drawback is that when the throttle is suddenly opened after a short period at light throttle the boosted charge is initially heated up as it extracts the latent heat that has built up in the system. This can give rise to a brief period of detonation - usually harmless but still undesirable. The same effect explains why supercharged engines often require minimal temporary fuel enrichment as the throttle is opened.

 

 

 

For highly boosted engines it can be better, not only to employ a bypass system, but also to place the throttle after the supercharger so there is no heat build up off-boost. A throttled supercharger on a racing engine, in the light load, high revving, condition during the seconds before the start of a race, can heat up nearly to the point of seizure, so as the car gets off the line both the blower and the engine (as the excess heat dissipates into the system) are under extreme stresses that do not apply at other times. Reliability is much improved with a bypass and throttling after the supercharger.

 

so am i just getting myself confused then,and leaving the throttle body where it is will be fine aslong as the bypass valve is doing its job properly.This was sort of my thinking earlier which is why i have now orderd a remote bypass off magnusun products.According to them this valve will be perfect for my setup.Iam going to plumb it in directly after the supercharger so it goes directly back into the intake pipe,less distance to travel.

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don't know exactly the problem you have, but on my Integra i had a supercharger and on the intake manifold it had a valve connected to the charger.

can't remember very well what was the purpose, but i believe it had to do something with keeping the engine running with the throttle closed.

this pics may help you with something.

 

http://img59.imageshack.us/img59/4724/cimg0702f.jpg

 

http://img811.imageshack.us/img811/4785/cimg0692.jpg

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the laminova cores did help to keep the air temp acceptable at higher boost,

as you may know centrifugal chargers generates lots of heat.

 

That is the long term aim if it all works as those laminova cores seem to be pretty damn good.got loads of write ups and peoples build pictures saved for future reference.

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Still waiting for this damn bypass valve,so descided to fit the inline sender for the electric fans and get rid of the crappy cappilary switch.Also sorted the wires out and got the relays out the way.The car is running again now ,was just down to dirty plugs,but like a numpty i connected all the pipes up and forgot i had removed the bov.Now the charger had no way of releasing pressure ,you can guese what happend.One almighty bang and a jubilee clip flying across the road,OOPS.I have the pipe going to the throttle body disconected now and the cone air filter hasnt been put back on yet.With the filter off and the intake pipe open the noise is a lot less,i can hear the exhaust over the noise of the charger.Armed with this information i think i am going to get rid of the power enterprise cone filter and look around the scrap yards for an airbox that will fit in the space i have.I was surprised how much of a difference it actualy made with the filter removed,you can actually change the note by placing open fingers over the intake pipe ,this makes it louder.

 

Just a thought would it be ok to plumb the bypass valve back into the airbox,instaed of going back into the pipe.Its part of the intake so hopefully it wouldnt make any difference.

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Edited by barneybrendan (see edit history)
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Been around the scrapyard and picked up 3 air boxes one from a mondeo,the other from a rover,but i cant remember what the third one is from for the life of me.As it works out the third one will fit best with a bit of cutting and glueing.S o if any body can tell me what its from that would be nice.The air filter is from halfords HAF402 ,but i still cant seem to find a link to what vehicle its from.

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Its been taht thick heavy drizzle all day here,but i couldnt let that put me off.The airbox is now fitted securely in place and plumbed in.The fuse box had to be moved up slightly,may need to have a little tweek as i think it might be catching the bonnet.As for the airbox itself that will be fed cold air from the bottom through a pipe.the housing came with a tight 90 degree rubber elbow which was perfect.The original intake pipe that i made was removed completely and i found some flexy intake pipe in the shed,this was the perfect length with just a 3" piece of stainless either end to join the couplings.What i am going to do when the bypass valve turns up today is plumb that directly feeding back into the airbox.

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