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NA engines, who's in the know ???


Suprash

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I thought the water feed to the throttle body was to stop it icing up in real cold weather. You think about how cold the air must be when rushing past at x metres per second if it's -5degC ambient - add some moisture and it could freeze the throttle open. Which would be bad.

 

Helps cold start, that's funny that is :) How exactly does it do that eh? By supplying heat? Er, the coolant is cold, that's why it's a cold start :D

 

-Ian

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Ian why do you say the conrod, I have just this dicussion with someone and they say the internals are exactly the same as the TT lump, only difference being the oil squirters ??

 

High RPMs is the only real way of getting big power out of an NA engine, and high RPMs put a massive load on the conrod at TDC on the exhaust stroke, and it's a tensile force, i.e. it's pulling the big end apart.

 

A TT would fall apart the same way, only they don't have to be revved to buggery to get power :)

 

-Ian

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I thought the water feed to the throttle body was to stop it icing up in real cold weather. You think about how cold the air must be when rushing past at x metres per second if it's -5degC ambient - add some moisture and it could freeze the throttle open. Which would be bad.

 

Helps cold start, that's funny that is :) How exactly does it do that eh? By supplying heat? Er, the coolant is cold, that's why it's a cold start :D

 

-Ian

 

Thank you Ian, a voice of sanity speaks out from the melee.

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Us vultures demand photos of nasty broken bits! What happened? Which bit let go? My money is conrod at high rpms :)

 

-Ian

 

Not far off Ian, No 1 big end Bearing, we used Toyota bearings, its now being rebuilt with Clevite 77.

 

I usually use Clevite, but this was our first Na so it was a bit of a test of the OE parts too really.

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Not far off Ian, No 1 big end Bearing, we used Toyota bearings, its now being rebuilt with Clevite 77.

 

I usually use Clevite, but this was our first Na so it was a bit of a test of the OE parts too really.

 

Now I'm not *that* up on engine internals so I'm interested in this - I thought that the bearing surfaces weren't supposed to touch metal-to-metal at all, and there is a oil bearing surface between them. The phrase "spun up a bearing" or "picked up a bearing" means, as far as I know, that the conrod has touched the crank while under load and speed, due to low oil pressure or oil starvation or something (overrevving!), and the bearing surface gets mashed up. So if that's correct - how does changing the bearing type make a difference when it comes to high rpms? If they touch it's lunched no matter what it is, it's just supposed to be smooth and nicely within tolerance to provide the perfect surface for the oil...?

 

I'm gonna poach this thread for tech :)

 

-Ian

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Guest supracar1995na

Good luck on getting permission to post on that site.I signed up days ago,and have since sent them e-mails and still NOTHING,not even a reply.I figure ....They wanna be that way,guess I don't need em.I go to all the other forums and have gotten advice from some great ,friendly people without having to WAIT to be included.Though my post on here hasn't gotten ANY replies,and I have a mystifying problem,so far it sounds like I'm gonna have to start cuttin wires in the dash.

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Now I'm not *that* up on engine internals so I'm interested in this - I thought that the bearing surfaces weren't supposed to touch metal-to-metal at all, and there is a oil bearing surface between them. The phrase "spun up a bearing" or "picked up a bearing" means, as far as I know, that the conrod has touched the crank while under load and speed, due to low oil pressure or oil starvation or something (overrevving!), and the bearing surface gets mashed up. So if that's correct - how does changing the bearing type make a difference when it comes to high rpms? If they touch it's lunched no matter what it is, it's just supposed to be smooth and nicely within tolerance to provide the perfect surface for the oil...?

 

I'm gonna poach this thread for tech :)

 

-Ian

 

Possibly a larger bearing standout? So that the clamp load on the bearing is much higher, and would presumably keep the bearing from spinning if the big end started to separate slightly.

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Thank you Ian, a voice of sanity speaks out from the melee.

 

I thought the water feed to the throttle body was to stop it icing up in real cold weather. You think about how cold the air must be when rushing past at x metres per second if it's -5degC ambient - add some moisture and it could freeze the throttle open. Which would be bad.

 

Helps cold start, that's funny that is :) How exactly does it do that eh? By supplying heat? Er, the coolant is cold, that's why it's a cold start :D

 

-Ian

 

 

So, is there a general consensus about this mod? It sounds like it could be worthwhile for summer to autumn times.

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Now I'm not *that* up on engine internals so I'm interested in this - I thought that the bearing surfaces weren't supposed to touch metal-to-metal at all, and there is a oil bearing surface between them. The phrase "spun up a bearing" or "picked up a bearing" means, as far as I know, that the conrod has touched the crank while under load and speed, due to low oil pressure or oil starvation or something (overrevving!), and the bearing surface gets mashed up. So if that's correct - how does changing the bearing type make a difference when it comes to high rpms? If they touch it's lunched no matter what it is, it's just supposed to be smooth and nicely within tolerance to provide the perfect surface for the oil...?

 

I'm gonna poach this thread for tech :)

 

-Ian

 

 

Right just spoke to Jason and he said the reason was due to the Rod oil exit clearences. He is re machining an NA crank for more clearence this week.

 

Basiacally the bearing could stand up to the heat which is why we are going clevite and widning the oil ways.

 

Widning the oilways is what we do to the big single engines too as a matter of course.

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Well like Ian or someone rightly pointed out :blink: whats the point in having the hose feed through your throttle body for cold winter starts when the water would be cold in the first place from you only just starting it, so what is the point of that design.....

 

I have had inlet icing in Spring too. I woudl never remove that system on teh stock system. Bad idea.

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