Anyone know how much pressure the Toda Valve springs are? (at stock installed height) My 'head guy' says stocks are at 70 lbs...

Sorry I suck with the head terms..

Chris

 

WOOOOOOOOOOOOOO YEAH!!! ... uhh.. yeah, ok .. thanks

 

You'll probably have to go to Toda to get an answer for this. I doubt many people that have installed the Toda valve springs actually measured their stiffness before installing them.
When my installer put them in, he said they felt like they could be almost twice as stiff as stock. Not very scientific, I know... but that's the best I can do.

 

Thanks for the info! What do you think about the Toda cams? I remember there were about 5 billion posts in a couple threads about them, but what was the end result?

Thanks

Chris

 

Ouch... that's a sensitive subject.
If you read the huge Toda cams thread (I think it's up to 20 pages now), you'll find my latest results. The cams were actually losing power vs. the stock cams. I haven't been able to explain why, yet. This is actually my second set of Toda cams, since the first set had the nose of several of the lobes shear off. Before they started to disintegrate though, the original cams made 5-8hp from 4500 RPM to redline on an otherwise stock motor.
The current cams are supposed to have the same profile, but used a different manufacturing process to make them stronger and less likely to fail. However, even though they're supposed to be the same profile, I can't get these cams to make power. I suspect they're just not timed properly, but I don't have adjustable cam gears (and the original cams didn't require them), so I can't understand why these would have a problem.

Anyway... the cams are currently out of the car, and I'm making just as much power with the stock cams. I've sent a couple of e-mails to Toda over the last week or so, but haven't received a response yet.

Click the link in my sig called "Dynos" and you can see the progress of my troubleshooting efforts. It's quite frustrating.

 

Chris

what are you planing to do?

 

I have ordered a set of dual valve springs. I am ordering new spring seats today, and I should have everything to put my head together with Black Nitrided valves... I wanted to be able to rev out to 10,000 rpm, and I told the shop that did another head of mine that, and they just did whatever they felt like it... now I have one head by alaniz with 1.5 over intake, and stock sized exhaust, and one head by another company with 1mm over on intake and exhaust. Want to buy the latter?

Chris

 

I am saving money. if the new business goes well next year will have $$$ for a Engine built, I will contact you.



Juan

 

To set up the correct spring "seat" force (not pressure) depends on many things, such as valve weight, spring weight, inertia of the rocker arm(s), acceleration of the valve (a function of the cam lobe design), etc.

To little spring force will cause valve "float" at a given rpm and too much force MAY cause the retainer to crack or the valve tip to break at the keeper groove (a high stress concentration point).

I have a single spring installed in my engine w/ titanium valves, retainers, and the center rocker arm removed. I turn ~ 11,600 rpm and have 135 lbs. seat force and 420 open force. I have valve spring design software that I used to get it right.

I don't want to scare you, but if you intend to turn ~ 10-10.5k you had better get it right the first time, because if you don't it won't be pretty. If you truely trust your engine guy, based on his/her experience or the cam manufacturers recommendations, you don't have to worry.

By the way, could you share the cylinder head flow figures on the head with the 1.5 mm larger intake valve?

Thanks,
Greenlight