4age Crank Info for 4agte usage

[oldeskewltoy]

this doesn't make sense to me, how would a harder surface tension stop distortion?

I did not get those specific details I did say I wasn't sure

[Sam_Q]

oh fair enough.

[oldcorollas]

it doesn't make sense.
shot peening puts a thin layer of compressive stress at the surface, which helps to stop fatigue cracks initiating.
it actually weakens the overall strength of a part (by a very very small amount), or can assist in distortion.

shotpeening, like cryogenic treatment, is often used a "fixall" by people who don't understand what they are doing, or by people who just hope there is some good effect.
many many "speed shops" and high profile engine builders do this too, figuring that if their competition does it, then they don't want to miss out, and better to do it and have no effect, than to not do it, and miss out.

so unless the caps have a possibility of forming a crack on their outer surface, there is no point to shotpeen.

however, it can be a good sign when you want to know what shops to avoid

[Sam_Q]

that's exactly what I was thinking but didn't know how to phrase it.

[oldeskewltoy]

fair enough... let me repharse..... knowing what I've learned over @ Loynings... it is far more likely they mentioned something that would harden the main caps and I mis-translated it and let it settle in my brain as shotpeening.

Their work is almost beyond reproach.......... almost

[dangdang]

What could be agreed is that shotpeening whilst not making the caps inherently stronger could stop cracks developing and thus failures occurring.

The main caps in these are already a chunky item, looks like billet caps and line boring as Bazda said could well be the ultimate for big boost & revs and be better than any fancy girdle or even straps.

[dangdang]

An update, just to bury anyone's doubts about the cranks being forged it is stated here in...

Translated mid 80's Toyota Twin Cam Press Guide, http://www.toymods.org.au/forums/sho...89#post1272189

On page 17, http://www.3sgte.com/page_17.htm, it states,

"After deciding on the four valve design for the 4AGEU, three sets of prototypes were produced. Additionally among other modifications, the crankshaft was changed from a cast to a forged item, and the number of flywheel instillation bolts was changed from six to eight to improve durability and reliability, and to prepare the engine for production."

This from Toyota's own mouth.

[RT40Corona4AGTE]

cool!..........

[Dongaz]

Dongaz: why not just go for the 1.5mm pitchnuts?

I think we found out that even with the 1.25mm on one end and 1.5mm on the other it ended up that the end with the allen key would be on the 1.25mm end and therefore would mean that you would never get the studs out.

do the caps actually crack? is there any real need for shotpeening?

This is Formula Atlantic 4age with TRD parts in it. It is from one of the rear mounted sportscars from the UK I think. Here are a few pics on the main cap that split.

The main issue that is faced with a high revving motor is that the main caps shift. Having them tied into the block with the full main cap cradle helps prevent this. This is also why alot of big V8's not only have the two bolts that go into the main caps vertically but also the two crossbolts.

With that being said I don't think the Tomei main cap braces that go on top of the caps would do as much as a full cradle. The only thing where it would help is being a different material type..I'm presuming billet it has a different ductility and strength and will prevent the bolts from pulling apart. Not sure if this would also stop the cap from shifting.

Anyway here are the pics. I also put up a pic of the sump to show that it is the dry sump system and the alloy sump on these also provide alot of strength compared to a normal (wet) sump.

I need to find the link to where I got the pics from again but I know he was turbocharging the motor. These pics were before the turbo.

[RT40Corona4AGTE]

yeeeooooucccchhh!

[Dongaz]

http://www.toymods.org.au/forums/showthread.php?t=50867

http://www.gtr.co.uk/forum/111976-to...ing-turbo.html This one has the most pages on it.

http://forums.club4ag.com/zerothread?id=33808
This one shows a pic of a build that someone else(Davegt27) posted up showing a main cap cradle.

[dangdang]

Interestingly the TRD/Atlantic bottom end doesn't run a stud bottom end then? As per the pics.

Bolt vs stud, stud wins every time from my speedway engine experience.

[Casey-G]

I wonder if thats a TRD or similar block, it looks a lot neater/different in the crank casing compared to the 4ag's ive seen

[dangdang]

I was neg repped for my above post.

I was simply pointing out that when my father ran his 265 Hemi in his clay track speedway car (an Australian built engine, before you neg rep me because you've never heard of one in Ameewica) He ran a studded bottom end, some of the others running the same engine experienced failures from using the factory style bolts.

I was just pointing out my surprise that the above engine didn't have a studded bottom, that if it had of perhaps the cap would have faired better, and wondered if this is how the Atlantics ran?

How about adding something to the thread instead of superfluously neg repping.

[dangdang]

I wonder if thats a TRD or similar block, it looks a lot neater/different in the crank casing compared to the 4ag's ive seen

It looks like the inside of the block has had all the casting dags ground and polished off.