why does my charger rattle at idle?? coupler fine, bearings fine....?

checked with stethoscope and it defo is the charger, loosened belt too still there..?

http://www.locostbuilders.co.uk/viewthread.php?tid=164583

Worth a read, follow the links to youtube...

If its an eaton then coupler is suspect, easy job to do and not expensive.

Regards Mark

I changed the coupler and oil before installing.. m45

has anyone ever had charger rattle because of slightly lumpy idle? the crank can transmit a small pull on the belt having a stop go effect on the coupling making a rattle..? even a new item will have a certain amount of lash?

my idler pulley is solid would a spring loaded one help in this case?

Is your vacuum operated bypass working OK? if not the charger is generating high vacuum at the closed throttle, this can make it run noisy at idle.

the valve is completely open at idle and excess air is venting. . .

I.m convinced its torsional vibration coming from the crank.. a lot of custom supercharger installs with this prob online, most off the shelf SC kits contain a crank pulley with torsional damper.. I'm kinda fooked!!

I'm going to try an automatic spring loaded idler in place of the solid one i have on to see if it absorbs the problem. . .

straw clutching now

You said the valve is open and excess air is venting? the vac operated bypass normally connects the inlet of the blower to the output of the blower. Is your throttle is on the inlet of the blower?
Did you mean the blow off valve? (like turbo dump valve)

I fitted a M112 to a rover V8, throttle on inlet, vac operated bypass, quite as a mouse.

Mapped a MX5 for a customer that was fitted with a M45, throttle in normal place (on engine inlet manifold). Rattled at idle!

I'm blowing through carbs so throttle plates are up stream from blower on inlet mani, no valves or bypass befoe blower and using a 50mm tial type BOV after blower before throttle plates

As soon as the throttle opens the valve shuts,,, its gonna be fun fine tuning that, cruising is difficult as the valve cant make up its mind!! It takes off like a rocket too!!

any advice most welcome!

If your running a "blow thru" system then as you say it will be a pain to tune, but not impossible, all depends on what carbs your are using.....what carbs have you got?

Are you using an intercooler?

Are you aware you will need a boost ref fuel regulator to keep the fuel pressure to the carb(s) above boost by a constant 5PSI?

Boost retarded ignition system is also very important.

If you give me a run down (and maybe pic's) of what engine spec you have i maybe able to save you some hassle!

I'm 95% sure your blower noise is caused by the way you are running it, most OE blowers are designed to have the throttle on the inlet, with a vac operated bypass.

With your system as it is now you have the blower pumping air at idle, with the throttle on the inlet the blower is pumping virtually no air at idle. Because you are pumping air at idle you maybe hearing "chatter" from the SC gears and coupler. You could prove this by covering (throttle) the SC inlet at idle, not completely, just enough to allow the engine to keep idling. If the noise stops then you will know.

Hi.. I'm most gracious for the help as this is my first attempt at something like this..

I will make up a bit of a project so far.. . . . . i built the engine too so i know whats in there

Engine spec-

Cosworth YB with ported head
10.5:1 CR
fast road NA newman cams 288 dur (the standard turbo cam might go back in to reduce overlap)
Accralite pistons
ZX9R C1 bike carbs
Innovate wideband
Megajolt TPS Ignition

here is the engine



starting from the air inlet





Out through to intercooler



come back into bay where the BOV is



just before it was installed. . . . went for the biggest valve I could get as I heard putting any back pressure on the charger shutting the throtttle at red line is very sore on belts and having a cogged belt means no give.. and the pulleys are quite small so that dont help much either.



Up next is the pilot tube, its to pressurize the carb float bowls and equalises the pressure. apparently this give an unfluctuated reference. or so I have read HERE




Then into airbox which has all been sealed up to the carbs, beyond throttle plates there are hosetails into each runner for the MAP.



Regulator is a mallory 4309 which will bring the 3 bar pump right down to 2psi and it does! a bit of overkill but a carb pump wont suffice, most put out 4-6 psi, I need 3psi+ what ever boost I'm running (+ extra for future upgrades), a 25 psi pump is £120+ mine was £32, the reg has a boost reference from the carb airbox and rising rate is 1:1.







Heres a vid of the engine running, apologies for the really bad quality!! you can see the BOV opening on closing throttle, just about.




I have test driven it and it bloody goes like a rocket, wheel spin in 4th, it drives well when your foot is planted with AFRs in the 12 region from 2500 upwards.. below there its very lean.. idle is at 14, changing needle heights helps but leaves the top end rich, need a different needle profile..

Driving on part throttle has the bov fluttering and the boost gauge all over the show, going from +/- very annoying, near takes off it self when the BOV shuts! Spring tension is key here?? Or do I need a completely different valve like a butterfly setup??

Boost at the min is low, about 4psi. cams are the devil here, i havent dialled any overlap out yet, but an NA 200ish bhp lump with 4psi goes quite well from a standstill. might put a standard exhaust cam in again. stop mix going out exhaust.

As boost is low and linear the 3D tps megajolt will work for now?, no pinking anywhere so far and if it does its easily reduced. might get a MAP megajolt later down the line.

Sorry bout the massive post! And no "just put a turbo on ya gack" comms, hehe

Big novice thanks

ETA- Ill take the filter cone off and cover inlet to see if the rattle stops next time i get to the garage. the BOV will still be open tho- that ok? or is this a bov closed test??

[Edited on 1/1/12 by Craigorypeck]

Hi,

first off i've got to say you have made a great job of the installation, very nice.

Couple of comments i've got to get off my chest first!!

It will be 1000 times easier to convert to fuel injection, your prob spend more time trying to get carbs setup than you would with mapping megasquirt, but if you want to stick with carbs then it can be done.

The blower is too small for a tuned YB, you need at least a M90. But that said if you only run very low boost it will be OK.

You are going the right way with high CR and NA cams, this way a very small amount of boost will make a big difference, we have done high CR turbo motors before with good results - throttle response is fantastic.

Ignition timing is critical with this setup, high CR means you will be running close to detonation with little margin for error, you can run a basic timing curve in the megajolt (no MAP) as long as you keep the total timing low. For example..

YB turbo stock, 1 bar boost = 10-16deg TOTAL timing

YB turbo high CR, big turbo (rally spec) 8deg TOTAL timing

YB Race 500BHP+ 4-6deg TOTAL timing. (30PSI boost)

I would expect you engine to require around 28deg WITHOUT the SC, 16deg with the SC at 8PSI. Your timing settings in the megasjold will look abit odd, you need around 16deg at idle, same at full throttle, more at cruse.

To start with i would set the timing at 16deg everywhere (fixed at 16deg) then add some more at light throttle when you have sorted AFR.

You will struggle with the carbs to get the AFR right off boost as well as on boost, this is because a carb cannot measure density, only flow. The metro turbo used an SU carb with a slight restriction in the carb inlet (funny looking black manifold bolted to the carb inlet) the had the effect for causing a bigger pressure drop across the the carb (and so the jet and needle) making the carb more sensitive to boost and easier to calibrate.

You are OK at 12 AFR at 8PSI max

Cruse 13-14 will do,

Idle 13.5 ish.

Ditto the bits of the above that I know owt about! I am putting together a supercharged vauxhall xe and it needs an m90 to make good power really. I know a chap making 250hp using an m62, but I am aiming for around the 350 mark. There is a guy in holland with an m90 on an xe making 340 ish. Also I would not evenconsider blowing through carbs, go for injection, bear in mind on the costs that your carbs are worth 400 ish, which is half a very good ecu. I am using a dta s60, which will also control water injection via stainless multi hole injectors ( from a vw 20v turbo of some sort ), this bit is a bit suck it and see but I think it ought to work, and all the commercially available water injection systems at reasonable money use very crude control andcomponents!

I bought the charger to sell on as it was so cheap but it found its way under the bonnet. space is very limited and theres only 10-20mm clearance at servo and bonnet. I know carbs are going to be less efficient and harder to tune but its on a budget so trying to get a decent result with what I got, the current CR and a few psi will make a good difference. im on pinto clutch and T9 so theres my limit too.
If I can get the BOV to behave on cruise it will be under boost at all times apart from closed throttle so in theory shouldn't be that hard to tune? the most important bit is top end fuelling as that where it can go drastically wrong and its in the right area straight outta the box.. good guess with my main jets.
Heres the 3D megajolt map I have now..


IF I were to go fuel injection I'd try and get a complete YB inlet manifold/TB/injectors and megasquirt it..

Hi,

Your ignition map didn't appear on your post?

The idle problem can be solved by adding an extra throttle body just after the air filter, this needs to be attached to the carbs / throttle peddle with a separate cable to it opens slightly before the carbs.

The extra throttle will shut off air into the blower at idle and very light throttle, but will have no effect at wider throttle (as it will be open further than the carbs at any given point).

If you get it set up right you dont need the blowoff valve, but wouldn't hurt to leave it on.

You need a reasonable size throttle body, a 2.0L silvertop zetec body would prob do.

I had thought of that too! Was looking at something like this maybe, i have 2.5" pipe.

New Alloy Universal Throttle Body 65mm 2-9/16' Intake | eBay
SEARCH EBAY STORE

I can easily get another cable on as i used to run a twin cable to a pair of dellortos

if i could find a TB with smaller radius cable wheel it would open sooner which would help.
would it need an idle screw adjustment too?

the normally functioning bov would then be a bad idea as it would be allowing unfiltered air into the system on closed throttle, could be left in place with no ref connected, a light spring to keep shut but blow off incase of back fire through carbs??

ill try my map again..

difficult to find a TB thats got a pipe connection on both sides all im seeing are single pipe to flange types.. any ideas?

thanks

quote:

---

Originally posted by Craigorypeck
difficult to find a TB thats got a pipe connection on both sides all im seeing are single pipe to flange types.. any ideas?

thanks

---

quote:

---

Originally posted by BaileyPerformance
You will struggle with the carbs to get the AFR right off boost as well as on boost, this is because a carb cannot measure density, only flow. The metro turbo used an SU carb with a slight restriction in the carb inlet (funny looking black manifold bolted to the carb inlet) the had the effect for causing a bigger pressure drop across the the carb (and so the jet and needle) making the carb more sensitive to boost and easier to calibrate.

---

quote:

---

Originally posted by MikeRJ

quote:

---

Originally posted by BaileyPerformance
You will struggle with the carbs to get the AFR right off boost as well as on boost, this is because a carb cannot measure density, only flow. The metro turbo used an SU carb with a slight restriction in the carb inlet (funny looking black manifold bolted to the carb inlet) the had the effect for causing a bigger pressure drop across the the carb (and so the jet and needle) making the carb more sensitive to boost and easier to calibrate.

---

This is what the Pitot tube does. The pressure in the pitot tube will depend on the density and velocity of the air at the point where the tube is mounted (on top of the local pressure).

---

I would pull the discharge cover off and see If the Teflon has been ripped off the rotor tips as that's what I found after running the throttle after the blower on my m45 . The vac bypass and blow off don't work well together with partial vacuum and the column of compressed air bounces between the throttle and supercharger putting pressure on the rear of the rotor case where the needle bearings are .

Mine caused more damage because I have a turbo as well but as said before virtually all o/e superchargers have the throttle at the charger inlet . I tested my m45 by pinning the turbo wastegate open and it's just too small for a 2.0 so Ive gone for an m62 this time

So I managed to get to the garage again for a bit of a fettle..

I removed the ref from the bov, it shuts and with my hand 99% covering the inlet pipe I can manage a stable enough idle. a lot of suction at the inlet tho, charger seems under quite a bit of strain, belt too.. Is this normal enough behaviour if I go with the TB at SC inlet?


Edited to add- I'm getting this pretty wrong aren't I?? Do I need a recirc valve instead of a BOV now? plumbed back in to the inlet after TB to equalise on idle??



Back to the reason for the first post... the rattle... I got myself a decent work shop light and got under for a look see when the car is idling and it actually seems to be the alternator?? Every time theres a rattle or vibration the belt can be seen visibly bouncing around on the alt pulley.. turned all lights on and it got worse.
Any ideas on this?

Many thanks for all the help so far!





[Edited on 4/1/12 by Craigorypeck]

[Edited on 4/1/12 by Craigorypeck]

Yep, you now need a re-circulating dump valve, piped from the outlet to the inlet of the blower, these cab be found on ebay- standard cosworth or saab Bosch (plastic) dump valve.

As for the noise alternator, could be loose fan? knakered bearing? As it changes when you load it maybe the field windings have become loose? hard to say really. I dont use the old type alternators, i find the bosch type (90A) used on the focus 1998-2002 zetec is a better unit. Internal fan, more stable output better suited to the EFI conversions i do.

Ok. Many Thanks again!!

Its making a bit more sense.. Ha!

I have a forge copy recirc valve that I was going to use vented to air way back when I first thought of this so that can go back into the plan! Pipe routing would be easier if the recirc valve was before the intercooler but where's best for it pre or post intercooler??

As for the alternator, (which is a new item) It may not have enough belt contact, not much more than 1/4 the pulley is getting belt... you can see in the 3rd pic of my install above.
I might need another deflector pulley in there.

Cheers
Craig

[Edited on 5/1/12 by Craigorypeck]

No problem ;-) happy to help.

Just had another look at your pictures, your prob right about the alternator pulley, it also looks abit small? i would aim for twice engine speed.

Your ignition map looks OK, but i would maybe take abit of timing out after 50% throttle as it will be under boost then, but overall i think you are close.

The best place for the dump valve piping is as close to the SC as possible.

Did you understand my post about adding a restriction to the mouth of each carb?

quote:

---

Originally posted by BaileyPerformance
No problem ;-) happy to help.

Just had another look at your pictures, your prob right about the alternator pulley, it also looks abit small? i would aim for twice engine speed.

Your ignition map looks OK, but i would maybe take abit of timing out after 50% throttle as it will be under boost then, but overall i think you are close.

The best place for the dump valve piping is as close to the SC as possible.

Did you understand my post about adding a restriction to the mouth of each carb?

---

quote:

---

Originally posted by BaileyPerformance
Agreed, the boost pressure is referenced to the carb(s) float chambers to the carb is effectively operating as normal (equalized pressure) if this tube was not fitted the boost would push fuel back into the tank, but this does not help in any way to the air density issue..

---

quote:

---

Originally posted by MikeRJ

quote:

---

Originally posted by BaileyPerformance
Agreed, the boost pressure is referenced to the carb(s) float chambers to the carb is effectively operating as normal (equalized pressure) if this tube was not fitted the boost would push fuel back into the tank, but this does not help in any way to the air density issue..

---

A simple tapping from the inlet plenum would not provide any density compensation, but a Pitot tube does.

If you check out the Wikipedia link, you will notice that the stagnation pressure of a Pitot tube is proportional to both the fluid density and to the square of the fluid velocity. This implementation is widely used on blow through turbo installations on bikes for boost compensation.

The restriction used in the Metro Turbo was simply another way of achieving the same goal. The terms work out to be the same, so the pressure drop is still proportional to density and the square of the flow rate.

---

The diaphragms are pressurized with equal boost above and below, with this not trick the carb into working as it normally would in NA operation??

ETA i was considering a perspex lid for the airbox so I could see in when I get it on the rollers, be interesting to see what the sliders are doing and how far they are moving.

[Edited on 6/1/12 by Craigorypeck]

Very interesting project, I like :-) would be even more interesting as you say if you could monitor how the carbs are behaving under boost.

quote:

---

Originally posted by Craigorypeck
The diaphragms are pressurized with equal boost above and below, with this not trick the carb into working as it normally would in NA operation??

ETA i was considering a perspex lid for the airbox so I could see in when I get it on the rollers, be interesting to see what the sliders are doing and how far they are moving.

[Edited on 6/1/12 by Craigorypeck]

---

yes, makes sense, fine tuning will see if I need such an adaption, what sort of restriction you talking?

quote:

---

Originally posted by Craigorypeck
yes, makes sense, fine tuning will see if I need such an adaption, what sort of restriction you talking?

---

Yes, small trumpets, they are playing a part holding the carb/backing plate/airbox together..

theres some twin side draught trumpet meshes in the garage would they do the job if needed?

quote:

---

Originally posted by Craigorypeck
Yes, small trumpets, they are playing a part holding the carb/backing plate/airbox together..

theres some twin side draught trumpet meshes in the garage would they do the job if needed?

---

Hi Dale.. i'll try getting it right this way first!!

went a visit to the auto electrical shop today with the alternator to get a new rear bearing.. they had the same alternator on the shelf, brand new items and guess what they have the same play in the rear needle bearing... so mine is ok, it must be completely down to the angle of the belt on the pulley. most alts will have 180ish degrees of belt contact pulling the spindle tight within the bearing. mine has way less contact allowing it to shake about causing my horrid vibrating sound.. ebay has a bearing set for £7 so I will change them anyways.
need to anchor another pulley in there now..

quote:

---

Originally posted by Craigorypeck
Hi Dale.. i'll try getting it right this way first!!

went a visit to the auto electrical shop today with the alternator to get a new rear bearing.. they had the same alternator on the shelf, brand new items and guess what they have the same play in the rear needle bearing... so mine is ok, it must be completely down to the angle of the belt on the pulley. most alts will have 180ish degrees of belt contact pulling the spindle tight within the bearing. mine has way less contact allowing it to shake about causing my horrid vibrating sound.. ebay has a bearing set for £7 so I will change them anyways.
need to anchor another pulley in there now..

---

gonna attach an other deflection pulley to a new laser cut alternator top strap and run the belt up and over to get more contact to the alt.

Just a random thought- Electronic BOVs? as my main problem with the crude setup i had was getting the boost to behave on cruise would a leccy BOV controlled by a TPS output from my megajolt work? Basically any throttle movement however slight would have the bov shut and the engine under boost with no fluttering and kangerooing that the reference vac/boost/bov spring were giving?

quote:

---

Originally posted by Craigorypeck
Just a random thought- Electronic BOVs? as my main problem with the crude setup i had was getting the boost to behave on cruise would a leccy BOV controlled by a TPS output from my megajolt work? Basically any throttle movement however slight would have the bov shut and the engine under boost with no fluttering and kangerooing that the reference vac/boost/bov spring were giving?

---

I have one of these, 25mm/1" bypass



and 4 different strength springs should do the trick?

also one of these on the way from china too- nice and cheap!

Perfect!! Should do the job!

solved the rattle with an extra pulley in the system, runs nice and quiet now.



BTW this guy- martinptownsend@aol.com laser cuts stuff from a cardboard templates at very reasonable prices, custom 15mm thick alt strap to mount pulley on, £7.50 delivered.