Belt arrangement unsupported length

[striker]

Hey all.

Have a few quiky's

I'm currently trying to decide whether I'll have the superchargers mounted low down on the sides of the engine or high up next to the cam covers.

High Pro's
no interference with the engine mounts
short intake length aids throttle response
looks nice

High con's
Longer belt runs unsupported
lot's of heat from exhaust system put in the chargers
Higher point of gravity (8.8kilogram each for the M45's)

Low Pro's
virtually No heat from exhaust into chargers
keeps engine smaller on top
shoter belt runs and doable with stock pully/belt route

Low con's
interfere with engine mounts unless I place them further outside the center line of the engine or incoorporate the engine mounts in the sc mounts
little more volume in intake system so less throttle response
Lower center of gravity.
Oil filter needs relocating

The thing is how long can a correctly adjusted (tension) belt run, unsuported by aditional tension pully's, Would 35cm be to long?

ofcourse any comments on the set-up much appriciated.

Grtz Thomas

 

[rms]

Thomas,
Move the lower CG to pro heading!
Another pro for low mount is provision for intercooler.

Recently finished plumbing a stock 4AGZE with SC12 charger, one of my intake manifolds and intercooler.
Layout was Air cleaner - charger - intercooler - throttle body - manifold, all plumbing and intercooler was 3" tube, vacuum bypass valve from before t/body to charger intake. 140rwkw at 9psi.

Really crisp throttle response, ECU fuel mapped from throttle position, ignition from manifold pressure.

I dont like driving superchargers with a pk belt, have seen many destroy belts once boost/rpm increase including OEM setups.
I prefer toothed belt drive. You dont have to apply tension to the belt and get positive drive.

 

[striker]

Hey Errol,

I Must say I very baised in making the low set-up work instead of the high mount system,

sorry bout the confusion I can't edit the message anymore.

Intercoolers will not be a problem at all, because I have a set of 4 laminova IC corse tucked away inside a new intake manifold.

I'm planning on making it work with the original 6 rib belt slippage will be devided by factor 2 compared to a single m90, and with the amount of wrap you have on the crankpully on the 1uz I would be surprized to that being a problem. If it need replacing every 5000km that's fine with me because it won't be a dialy driver. if it breakes 2 times I'll probably take a set of timing pulleys and make up a new system.
I'm not going to rune high boost at all, at leats not higher than BMW intended to and they get away with this type of belt with room for more, so I think I'll be OK.

A friend in the sylva corner has just finnished a 4age 20v silvertop (stock engine) running a Rotrex C30 charger and he's doing 266hp at the wheels at the moment limmited to 7krpm, mapping wil carry on up to 8k once the slightly bigger pulley is in he was at 1bar over @7000 without knock but he darren't push it further in boost. still very happy with my 161hp though

Question of How long a belt may stay unsupported remains, 35cm is the longest run on both applications, Will the belt start jumping or not in this length?

grtz Thomas

 

[Lextreme II]

Hey Thomas,

Another issue of top con would be hood clearance. Your project sounds very interesting.

 

[striker]

No problem david, not going in a lexus and hood clearance is just the reason for small twin side mounted chargers instead of one big on top. only got 60cm from bottom chassis to hood.

anyone on the path of the belt? would I need support pully's?

I tried to look some pictures up in google but those are all NA which doesn't put half the strain on the belt, so I'm not sure about them either.

found a way around the engine mount problem, the sc's will be part of the mounts, there's one nice option to do this on the mini items, must take piccie to let you see what I mean.

grtz Thomas
​

 

[Lextreme II]

Thomas,

If you have room you can place them in the AC and Alternator position. From there you can easily interooled the system.

 

[striker]

I have picked up a much smaller 4age alternator yesterday the center axle is the same as the 1uz altenator so I can exchange the 5rib for the 6 rib pully, the 4age can be placed higher up on the engine without interferring with the tubular exhaust manifold, then the supercharger pully will take place in the spot where the stock alternator normaly sits, it then hugs the block quite close which is indeed nice. (might be tempted to try a daihatsu one aswell which is even smaller)

The other side interferes with the oil filter location, I would like to keep that in the stock position because it's easily serviceble in the GD chassis in that place, so the second charger will be placed a little higher up to clear the oilfilter and cooler
(additional cooling will be dealt with when the chassis is in because I have quite a lot of rads to put in at this point I migh5 be tempted to go with a Laminova/Mocal oil-water cooler anyway)
I can't get the pully in the same place where the power steeringpump normaly sits, it's not far of (7 to 9 cm) I just wish there was a mirrored image of the m45 for this application..... helas.

anyway the chargers will be an integral part of the engine mount or the engine mount will be an integral part of the sc mount. I hope I can get away with the last option. which makes it far easier to pull the engine out of the chassis when needed (let's hope not hahaha)

discovered that SKF make a nice bearing with an 8mm centerhole 50mm diameter and same width as a 6rib belt, so if there needs to be a additional support for the belt on the oilfilter side of the engine that easy done, M8 holes enough scattered in the front of the engine to place it.

Grtz Thomas

 

[striker]

Thomas,

If you have room you can place them in the AC and Alternator position. From there you can easily interooled the system.

Thanx problem solved, only need one aditional extra support pulley.

grtz Thomas