Honestly, custom rods and pistons are "easy". Once you are in the realm of custom rods and pistons (let alone cranks) it is almost always the case that the valvetrain is more of the problem than the rod ratio. If noone has gone far enough to break the valvetrain, then noone knows where it breaks. Eventually someone will find out.
The rods are the only thing that would need to be custom.... i can get F2 rods, don't think i can get G6 rods.
I can get F2 pistons, which is all this motor would use. My THOUGHT is that with the decreased piston speed, the rods might be good for more power than before. Just a guess with no sort of factual background
Other than that it took 547wtq to break an F2 rod, and i'm still not 100% convinced that the rod went out by itself. I can always cryo-treat and/or shot-peen them to help myself sleep at night if it comes down to it.
Super Stock:
http://www.youtube.com/watch?v=f4IxzhtjcjA
But as modified as this is, it may get you to stop thinking about stroke being a bad thing:
http://www.youtube.com/watch?v=otv7P9wZsjY&list=PL2DC1E59773C5B898
Ford Pinto engines get the wee revved out of them in Merry Olde.
On this side of the pond, its big brother the Lima engine regularly sees 9700rpm in midget racing because the rules would limit them to that. You can buy an off the shelf 3.2l tall deck Lima that will turn over 10k and make over 400hp on pump gas. Still with 2v/cylinder.
Swank wants a high rev engine because he's jelly that my E36 M3ty Honda spins to 9k.
Spoolpigeon wrote: Swank wants a high rev engine because he's jelly that my E36 M3ty Honda spins to 9k.
Really i'm just curious as to how terrible it's going to sound. 
What does a cow in heat sound like if you play it in fast forward?
It can't sound any worse than a KLZE
I wouldn't be surprised if an 8 valve SAAB c900 engine could do 8k rpm with the right valve springs.
What I'm wondering about is the turbo and asking it to operate efficiently from 2,000 to 8,000 RPM or even higher. Or is this mostly a non-issue?
pres589 wrote: What I'm wondering about is the turbo and asking it to operate efficiently from 2,000 to 8,000 RPM or even higher. Or is this mostly a non-issue?
That's not entirely realistic. The more attainable and realistic goal would be 5,000 and higher. The achievable stretch would be 4,000 and higher, probably tapering off a bit up top. Maybe. Considering i just saw a DSM trap 158mph in the quarter mile running a Holset HX40, and knowing that the F2 already spools that turbo faster than the 4g63, who knows.
In reply to Swank Force One:
Yeah but will a de-stroked F2T, down to the same size as the 4G63, still spool that same turbo as well as a real F2T? This seems doubtful.
It also sounds like the build may result in a motor that hits boost like a hammer. The stock F2T doesn't do that and I always thought that was a bonus on the street vs, say, and early Audi turbo-five.
In conclusion, I think you've lost your mind again, but I am still enjoying the discussion.
pres589 wrote: In reply to Swank Force One: Yeah but will a de-stroked F2T, down to the same size as the 4G63, still spool that same turbo as well as a real F2T? This seems doubtful. It also sounds like the build may result in a motor that hits boost like a hammer. The stock F2T doesn't do that and I always thought that was a bonus on the street vs, say, and early Audi turbo-five. In conclusion, I think you've lost your mind again, but I am still enjoying the discussion.
I bet with the additional work "needed" to let it breathe enough to bother revving it, it'll spool ALMOST as quick as a normal F2T.
The stock F2T doesn't hit boost like a hammer? Well... maybe not with a stock turbo. Mine does. Always has. It's actually smoother now with the head work i did this time around in terms of building in a linear fashion rather than nothing nothing nothing.... ALL OF IT. However, it's also building much earlier, which isn't terribly useful in a FWD application.
Example of previously 100% stock F2T wearing a CT26 on (very) low boost previously doing an entirely legal pull in another country that doesn't have speed limits.
http://youtu.be/i8Pgea50SsE
The crazy "slam" effect is more apparent when starting from a lower RPM rather than right in the meat as it is from 30mph in 2nd gear.
And it was significantly worse on 24psi.
On a motor theoretically seeing say... 9000rpms, i'd be perfectly happy not achieving full boost until 5000rpms.
Some of the speedfactory d16 drag motors were doing 9100-9600 RPM. I think those were all 500+ hp motors too.
I suppose my next question is: How do i accurately figure rocker ratio?
The Yugo/Fiat SOHC came stock with dual valve springs, and at least in 1300cc X1/9 trim, is said to be best driven in the red zone on the tach between 7 and 8k.
The F2T came with valve springs so weak that i can compress them about a half inch between my thumb and forefinger.
I put duals in it. It doesn't feel anywhere close to the same motor anymore.
I may have an "extra" FET crank if you were thinking of going that way. It's in a motor right now and I don't know the condition.
Spoolpigeon wrote: Swank wants a high rev engine because he's jelly that my E36 M3ty Honda spins to 9k.
Pffff do you even rotary, bro?
Honda EW3/EW4. 10k all day. .040 over, integra pistons, ITBs, Titanium valve springs & retainers.
DaveEstey wrote:Spoolpigeon wrote: Swank wants a high rev engine because he's jelly that my E36 M3ty Honda spins to 9k.Pffff do you even rotary, bro?
Not personally, but I remember an old friend pegging a 10k aftermarket tach in an FB lol
Mexico doesn't have speed limits!?!?
The rods are the only thing that would need to be custom.... i can get F2 rods, don't think i can get G6 rods. I can get F2 pistons, which is all this motor would use. My THOUGHT is that with the decreased piston speed, the rods might be good for more power than before. Just a guess with no sort of factual background
Well..
The thing about custom pistons is that you can move the pin location up in the piston which improves the rod ratio without changing the crank, CAN make the piston shorter which means less weight per given material, and allows you to use a lighter material than stock which makes your rods 'stronger' (able to handle more rpm).
So custom pistons and rods definitely reduce the need for custom cranks in the sense that you can get a lighter piston that allows for a longer rod (better rod ratio), and a longer rod that is stronger and probably lighter than stock, and all of this reduces the forces trying to tear the rod apart during the intake stroke at high rpm.
Piston speed is not really a rod durability issue so much as piston acceleration. Higher rod ratios slow down the acceleration somewhat.
I say if you are going to mess with custom crank work, do the whole shebang and get custom rods and pistons too.
http://www.youtube.com/watch?v=YI8G0a2eWKo
I haven't been able to find a video of the engine in a race car yet, but I'm quite sure they could got to 9K.
poopshovel wrote: Honda EW3/EW4. 10k all day. .040 over, integra pistons, ITBs, Titanium valve springs & retainers.
So, just to be clear, you'd stick it on a dyno and run it at 10k for, oh, an hour at full bellow?
Knurled wrote:poopshovel wrote: Honda EW3/EW4. 10k all day. .040 over, integra pistons, ITBs, Titanium valve springs & retainers.So, just to be clear, you'd stick it on a dyno and run it at 10k for, oh, an hour at full bellow?
Yes. That's EXACTLY what I said. It'll do it just long enough for a couple-9 solo II national championships and podium spots anyway (shrug.)
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