ae92 engine build?

[freakinbox]

Say I was to build an engine for my sr5 w/e it may be. How would I know the rpm limit after I was done?

I have a feeling this should be in the tech forum?

[toyotaspeed90]

depends on the motor & what goes in

really, since these are non interference motors you can kinda guess & check the limit via valve floatage. if you have valve springs that can handle it, (say in a 4age) you can probably go to 9,000 on an otherwise stock motor

[REN69]

I always wondered the same myself.. how would you tell the redline after modding a motor? My guess it's that most likely you would be able to tell where the motor would redline by dynoing it.

[Flashmn]

Redline is also the limit where engine harmonics start to tear things up. Overrevving can snap a crankshaft too, oftentimes its the valvetrain that limits, but bore/stroke is also a limiting factor as pistons speeds go too high.

[toyotaspeed90]

for the most part, stock 4age's are VERY well balanced. Most shops that you take bottom end 4age parts to have balanced usually say they practically didn't need it. & make sure the flywheel is balanced correctly as well.

and this is part of the reason why 4age's don't have harmonic balancers

[Flashmn]

Toyota in general has close tolerances, but 4cyl engines arent that great in harmonics, they are inherently unbalanced, thats why alot of manufacteurers put balancing shafts in their car. Mitsu has them in the 4G63 for example.

and this is part of the reason why 4age's don't have harmonic balancers

I could of swore I saw such on a 4A-GE, btw FYI, the narrow crank should have it, because they have a tendency to snap in two if they dont. the wider one sustains more punishment.

[punter]

Originally Posted by Flashmn

4cyl engines arent that great in harmonics, they are inherently unbalanced

Please explain why you think this.

The very nature of an inline 4 ensures they are well balanced, ie. 2 pistons going up balanced by 2 going down, its a hell of a lot better than a v6 or v8 configuation.

All that is needed for balancing is to ensure that all the rods+pistons are of the same weight and that the flywheel+crank are balanced togeather.

As for the original question, the rev limit of an engine is dependent on the components used. So a vauge question like that has no answer.

[Flashmn]

The very nature of an inline 4 ensures they are well balanced, ie. 2 pistons going up balanced by 2 going down, its a hell of a lot better than a v6 or v8 configuation.

Dead wrong. Engines divided by 6 are ALWAYS balanced (except for V6, as thats not really a 6 cyl, but 2 3 cyl blocks.) V8's are two inline 4's put together.
I'm not gonna go further into explaining this, just use google or something and you'll figure it out.
I'll be friendly enough to provide you with a link. Just read the first paragraph.
http://en.wikipedia.org/wiki/I4

[punter]

Originally Posted by Flashmn

Dead wrong. Engines divided by 6 are ALWAYS balanced

I never said they weren't, infact they're the best. But the fact remains that inline 4's aren't badly balanced especially small displacement ones.

Originally Posted by Flashmn

4cyl engines arent that great in harmonics, they are inherently unbalanced

The toyota A series motor don't use balance shafts, and are capable in factory form of reving past 8,000rpm due to being accuratly balanced. Inline 4 race motors do not run balance shafts, many of which run well over 10,000rpm.

Doesn't sounds "inherently unbalanced" to me.

Basically all balance shafts do is make an engine run smoother, they don't aid performace.

[freakinbox]

so the parts I buy will have a max rpm rating?

[punter]

Originally Posted by freakinbox

so the parts I buy will have a max rpm rating?

In a sense, they won't have it printed on the box or anything. As said above the valvetrain is was normally defines the rev limit. And after you have fixed that with A/M valve springs your rods would probably be the weak spot.

Anyway why would you care how many revs the motor you may or may not built will pull.

If your looking to build a performance motor, you need to decide a budget and a realistic performance target, then you can decide what parts you can use.

[freakinbox]

I care because I don't want to go over it and blow the motor? because I would if I didn't know.
I was thinking of using a 4age 16v. Probably the big port. getting it bored out, larger valves. buy stronger internals. Port and polish. better cams. new pistons and connecting rods, bearings and so on. then other things like the ecu would have to be changed or modded (not sure how I go about that but when the time comes I will read up on it), fuel injectors would have to be changed ummmm...

I am thinking a 4age with a stronger crank, better valve springs and piston rings should be able to go over the 8500 rpm limit but when I am done like I said I want to know how high it can go.

[Flashmn]

But the fact remains that inline 4's aren't badly balanced especially small displacement ones.

Are you hard headed or something? even the website says they're one of the worst engines there is regards to balancing.

The toyota A series motor don't use balance shafts, and are capable in factory form of reving past 8,000rpm due to being accuratly balanced. Inline 4 race motors do not run balance shafts, many of which run well over 10,000rpm.

Yeah... I realize that, but with what kind of durability? Race engines and street engines have quite alot of difference, one of them is that they only have to last that particular race, you can use parts that wear out every race, hardly something you want in a street engine.

[toyotaspeed90]

i can tell you from expereince, from friends experiences, and from experienced people that the 4age's are nearly perfectly balanced from factory.

the 4age i pulled apart down to the block (which is still sitting in my garage) had no balancer. The pulley is just a crank pulley and the flywheel obviously isn't a balancer. However, 4af's and 4afe's DO have harmonic balancers....

and the 4g63 isn't a well balanced motor from stock. In fact, most chrysler motors are absolutely terribly balanced.... and i've heard of some of their v8's not being measured in amounts of grams not milligrams being taken off to balance them.

[Flashmn]

Oh I know 4A-FE's and F's have harmonic balancers.
Does your 4A-GE have the thicker or thinner crank. Thinner ones should have the harmonic balancer, the thicker ones dont have to. Thinner ones snap in two if they dont have such. just FYI.