7AFE Conrods, When Do They Bend or Break?

[MRMOPARMAN]

Spool rods are meant to be very close in their tolerances. I think that if a new part doesn't fit right up then it should be sent back

I hate the spool rods.
When they size them they don't use the bolts they supply with the rods - take em out the packaging & torque up the bolts properly & the big ends are out of round 8/10 times - I've sen them as bad as .0005" out of round brand new.
The small ends are also often undersize - pins won't fit.

So they cost what the rods cost + cost of sizing the big & small ends - which brings them to the cost of a decent set of rods that'll be good to go out the box.

Scat shits on spool, but I'd take spool over eagle.

I don't see the need for a built bottom end with only 160rwkw. If the rods stay straight and properly attached to the crank, there is no need.

If the power bug does start to nibble, I'll go a built engine with new rods and forged pistons.
I'll be pushing the little R34 GTR turbo pretty hard to get what I'm after and they use a really small turbine inlet (I'm aiming for the smallest, but still well flowing exhaust system volume from exhaust valve to turbine wheel) which is in line with my intended 'big fat torque curve (for a 1.8)' requirements for this engine. So if I do start chasing big HP, I'd need to at least modify my exhaust manifold so the collector's outlet is bigger to match the usual T25 turbine housing inlet size.

fair enough. ive never seen 7A pistons, but going off some other N/A Toyota pistons, I wouldn't expect the ring lands to last forever, especially if you are potentially overspeeding an overly small turbo. doing that can make a motor more prone to detonation. do R34 turbo's have ceramic wheels like the older Nissan turbo's? id be treading carefully there. I think a GTiR T28 would be a much better sized turbo (they have a smaller turbine than the silvia T28's.

[oldeskewltoy]

I don't like to quote unconfirmed information but apparently........

thanks Sam...



7A-G, bigport pistons, stock deck height, 7A-FE head gasket = 10.3:1
7A-G, bigport pistons, block decked .024" (0.6mm), 4A-GE HG = 10.3:1
7A-G, bigport pistons, stock deck height, 4A-GE head gasket = 9.7:1

7A-G, smallport pistons, stock deck height, 7A-FE head gasket = 11.3:1
7A-G, smallport pistons, block decked .024" (0.6mm), 4A-GE HG = 11.3:1
7A-G, smallport pistons, stock deck height, 4A-GE head gasket = 10.6:1

7A-G, 8.0:1 early GZE pistons, stock deck height, 7A-FE head gasket = 8.8:1
7A-G, 8.9:1 late GZE pistons, stock deck height, 7A-FE head gasket = 9.8:1

7A-GE with stock 7A block, silvertop pistons and head, 7A 0.6mm HG = 11.55:1
7A-GE with stock 7A block, silvertop pistons and head, TRD 0.8mm HG = 11.48:1
7A-GE with stock 7A block, silvertop pistons and head, 4A 1.2mm HG = 11.35:1

[Sam_Q]

In this case I said that because I remember reading it but couldn't remember where and who posted it. I as a habit avoid giving out information that I have not personally verified or know the guy who has. In this case it was one of those things I heard but didn't know who it actually happened to.

With this chart above it's important to note that you can't use a 7afe head gasket with a 16V head. The water flow of a 7afe is near identical to a 20v and if used with a 16V the front cylinders will run colder than the back. Also why does the compression ratio go up when the gasket get thicker?

The info on the Spool rods sure is disappointing, I was under the impression they where decent. I do hope the Brain Crower rods I have here are in spec.

[MRMOPARMAN]

heres the thread if your interested.. also goes into CP piston failures. do a search on threads started by TK while your there for sexy headwork.

spool rods and cp pistons.

[Hiro]

7A-GE with stock 7A block, silvertop pistons and head, 7A 0.6mm HG = 11.55:1
7A-GE with stock 7A block, silvertop pistons and head, TRD 0.8mm HG = 11.48:1
7A-GE with stock 7A block, silvertop pistons and head, 4A 1.2mm HG = 11.35:1

Also why does the compression ratio go up when the gasket get thicker?

Unless I'm blind, comp. ratio is going down with thicker headgaskets according to that table...

[BLK_20v]

This thread makes me laugh... ae112 sportivo is a stock 7afe engine with a turbo slapped onto the side.

I'm running a 7age silvertop with stock 7a rods and bolts, 4age blacktop engine management and can swing it to 8k, I don't all the time, but i've just put 20,000kms on it without issues. I do hit the limiter but i'm not an idiot who holds it there mid drift.

[Hiro]

This thread makes me laugh... ae112 sportivo is a stock 7afe engine with a turbo slapped onto the side.

With 8psi, 9.5:1 compression and only 115kw at the fly...

That and they only made 110 of them, so not a very big sample size for collecting failure statistics (that and other stuff tends to stuff up on them first, like turbo manifolds cracking and the $10k TOMs ECU blowing up)

[Duk]

fair enough. ive never seen 7A pistons, but going off some other N/A Toyota pistons, I wouldn't expect the ring lands to last forever, especially if you are potentially overspeeding an overly small turbo. doing that can make a motor more prone to detonation. do R34 turbo's have ceramic wheels like the older Nissan turbo's? id be treading carefully there. I think a GTiR T28 would be a much better sized turbo (they have a smaller turbine than the silvia T28's.

Not sure about the ceramic turbine wheels in R34 turbo's.
Careful treading will come in the form of variable flow water injection and knock sensing for the Adaptronic. Obviously good tuning, too.
A low water level switch will also switch off power to the boost control solenoid valve and change to the other, more conservative (so a combination of less boost, richer on boost mixtures and suitably safe on boost ignition timing) maps in the Adaptronic.

[PrettyCoolWagon]

...

btw.. the spools will probably need machining and prepping off the shelf anyways.

Yep. That's correct, I bought spool rods and had to get big and small ends machined..
IIRC some of the big ends were slightly over bored requiring surface grind on the bolting face followed by re-bore, ...but that engine builder over quoted me on a lot of things and spun some B.S. ...In the end I took my parts elsewhere and got better service + price.
...but yes definitely any aftermarket rods are going to need some degree of machining $$ to mach your crank and bearings.