Ruuning Without a Balance Belt...

sawood12 · Oct 29, 2008

On the contrary - Torque is the only thing that matters - bhp is largely irrelevant. You stick a hyabusa in a 944 and it will go like a milk-float unless you have a 20 speed gearbox. Torque is the 'twisting power' that actually turns shafts - not power.

Anyway, back onto topic - the experiences i've read about from people running their cars without balance shafts is that the stock engine mounts are pretty effective at dampening out the vibration so you might not notice a vast deterioration, however don't expect the engine mounts to last long.

Fen · Oct 29, 2008

I concur - and I think said so (in different words perhaps) on page 1. Well engine mounts and oil pickup (after Pauly reminded me).

944 man · Oct 30, 2008

The mounts aren't that much of a concern... They're weak on early cars anyway: the later parts are far stronger but they all suffer on the off (exhaust) side. The oil pickup pipe I didn't know about though and that is more of a concern, obviously. How common a problem was it?

Simon

Fen · Oct 30, 2008

My research suggested it was more when it breaks than if it breaks if you don't run the balance shaft.

Having said that bracing it works - you're only trying to stop the thing vibrating due to the weight of the head and gauze on the end of the pipe causing a stress fracture. If you can stabilise the head then it won't vibrate and hence won't break.

Thinking laterally I wonder if you could cut the pipe near the block and insert a flexible section to simply allow for the vibration, possibly with some wire to help keep the pickup in pretty much the same place if it might swing around too much. A couple of hose clamps and some pipe of a suitable diameter and temperature / oil resistance would suffice, though I'd probably want to flare the pipe either side of the cut to make sure it doesn't slip off.

Personally if I had a dedicated track 944 I'd probably remove the balance belt and take the shafts out and address the oil pickup issue. I almost did it anyway.

Neil Haughey · Oct 30, 2008

OT but as Fen likes turbo's V6's and Audi's the engine out of a old crashed S4 is the way to go then. I don't know why I didn't think of it earlier.

TTM · Oct 30, 2008

ORIGINAL: Mike_Dawson
Chevy V8 is more compact than a Duratec or a Hayabusa? Really?

Obviously not - I was comparing it with the 944 turbo engine which is incredibly uncompact for a 4 banger.

Fen · Oct 30, 2008

ORIGINAL: Neil Haughey

OT but as Fen likes turbo's V6's and Audi's the engine out of a old crashed S4 is the way to go then. I don't know why I didn't think of it earlier.

On the face of it that might not be a bad suggestion. Much easier to find a crashed Commodore HSV with the LS1 in it though...

Mike_Dawson · Oct 30, 2008

"Forget engine torque..."? Mike, with the greatest of respect, this thread was started because I wanted to hear about peoples experiences (or knowledgeable opinions) about running a 2.5l car without a balance belt: not to listen to foolish prattle about bike engined 944s with sequential gearboxes.

Merely responding to previous postings by others, or is that not permitted on "your" threads? [

]

On the contrary - Torque is the only thing that matters - bhp is largely irrelevant. You stick a hyabusa in a 944 and it will go like a milk-float unless you have a 20 speed gearbox.

Odd that, because it's power to weight that defines performance, not torque to weight. If performance is key, then engine torque is irrelevant, Current F1 engines do not produce much more engine torque than a family saloon, probably less than a 3.0 944. With regards to gears, 6 or 7 would be sufficient, if changing gear is a problem then I suggest an auto [

]

And back on topic.

944 man · Oct 30, 2008

'Power' is just a way of describing torque in relation to speed.

MIB 959 · Oct 30, 2008

I have run with the balancer shaft 180 degrees out. The vibration was intolerable. It appeared after new belts were fitted by an independent
" specialist" who prepared 968s for racing, so I thought they were dependable. They would not admit liability, & the fault was diagnosed by a local OPC, who even guessed ( correctly) the identity of the incompetent outfit !

MIB 959 1990 S2 Black 66K miles, owned from 6 months
old, from an East Anglian OPC, said to have been the
M.D.'s car. I once had a 1980 911 SC from new, also
the ' M.D.'s car '. I suspect this is code for
" Demonstrator " !

Neil Haughey · Oct 31, 2008

ORIGINAL: Mike_Dawson

On the contrary - Torque is the only thing that matters - bhp is largely irrelevant. You stick a hyabusa in a 944 and it will go like a milk-float unless you have a 20 speed gearbox.

Click to expand...

Odd that, because it's power to weight that defines performance, not torque to weight. If performance is key, then engine torque is irrelevant, Current F1 engines do not produce much more engine torque than a family saloon, probably less than a 3.0 944. With regards to gears, 6 or 7 would be sufficient, if changing gear is a problem then I suggest an auto []

And back on topic.

Sorry for more OT, but one doesn't even require gear changing just a different final drive ratio (the transmission is a torque multiplier remember). The NSX was a good example, road testers said the latter versions had the most aggresive 2nd gear acceleration of any car this side of the 911 turbo, the NSX never had a lot of torque.

Back on topic, I don't think a 944 will be a very pleasant place to be without the balancer shafts working correctly. I remember when I had a duff engine mount fitted, the garage said it felt like the balancer shaft was out of allignment (but turned out to be a engine mount that was bad from the factory as it failed within days of being fitted). The vibrations especially at low rpms where so bad I didn't want to drive the car, it was like an old tractor.

sawood12 · Oct 31, 2008

Power seems to have been the currency people use to compare different cars, however it is not necessarily the case that the a car with less power is the slower car. There is so much more to it than that. If your engine develops more torque then it can push higher gear ratio's therefore more wheel RPM for every engine RPM and more speed and acceleration. Motorbike engines don't develop enough torque to power a car. That is just a simple fact of life - if not then why aren't all cars powered by motorbike engines?

Though it's true that power is a function of torque there is more to it than that as 944's developing the same bhp can have completely differet torque values and torque curve shapes.

The Hodna vTech engines develop good power due to the high RPM but not very good torque. The higher rev limit means that although you are pushing a lower gear (due to less torque) you have more RPM so you have better accelaration and are able to hold it in gear longer. But i've driven a Civic Type R and to be honest it was rubbish in terms of power delivery. It made alot of noise, didn't really feel like it was going as quickly as it sounded, and the engine just felt a bit guttless. To get any meaningul accellaration out of it you have to thrash the living daylights out of it. It got very tiresome very quickly. Not my cup of tea - I prefer torquey blown engines.

F1 engines don't make much torque - but they don't need to as the cars themselves don't weigh alot. They have more in common with motorbike engines than car engines.

I guess you really need to be comparing the size of a 944 4cyl engine with a 6 cylinder engine as most engines of 2.5ltrs or more tend to be 6 cylinder engines. Therefore I guess given it's capacity the 944 engine is not much larger than a 2.5ltr 6 pot engine.