New 2056 with big valve 2.0 heads in progress!, I have done various searches and have not found good info on this subj Options

[gothspeed]

Thus far I have decided on:

2056cc with around 8.5 compression

44mm intake and 38mm exhaust valves on lightly ported 2.0 heads (in progress)

44mm IDF webers or 40mm depending on more feedback (though leaning 44s).

Custom exhaust with 1.625" primary tubes.

I want to be able to rev to 6k maybe 6.5k max RPM

I have tentatively decided on the Web Cam 494 grind camshaft with specs below:

--------------------------------------------------------------------------------
Web Cam
Part #: 00-682
Grind: 494

--------------------------------------------------------------------------------


----------------------------Intake ----- Exhaust
Valve Lash (Inch):-------.006 ------ .006
Valve Lift (Inch):---------0.465 ------0.465
Valve Lift (mm): ---------11.81 ------ 11.81
Advertised Duration:-----280° --------280°
Duration @ 0.050":........244° ---------244°
Lobe Center:.................108° ---------108°

So now the question:

Using 44mm and 38mm valves, standard 1.3 ratio rockers with a 494 cam, what is the RPM limit using standard 'single' HD springs?

My only concern with Dual Springs is the added stress on the rocker shaft studs that are in 'old' aluminum heads. I would like to run Single springs unless there is no way they will hold up.

What do you guys think?

[VaccaRabite]

If it were me I'd shoot for 9:1 compression and run premium fuel. Compression is an easy way to get power, and a 2056 loves 9:1 compression with carbs and that cam. Dunno what the rev range would be with single HD springs. I assume that HD is stiffer then stock?

Zach

[blitZ]

I don't think it's going to gain anything from revving that high as horsepower drops off after 5500. I have a 2056 with 9:1 compression and dJet and heavy springs and retainers. It just beefs up the valve train a little.

[Root_Werks]

TQ magic RPM to remember is 5250 and of course it's been hashed a million times over, TQ=Acceleration, HP=Top Speed (most of the time).

Without stabbing gabs of financial resources in a T-4 engine, reving it much past 5000rpms won't do much becuase of the law of diminishing return.

Use to be higher comp|ratio was the cheap and easy way to get that TQ number up. Gas today doesn't really support it without knock sensors etc.

(IMG:style_emoticons/default/agree.gif)

People are giving you sound advice.

When I go through mine, it'll probably be 9:1, Jakes cam kit for FI and mildy cleaned up ports on the heads. I figure with my L-Jet (Gonna probably have to get those 187cc injectors), I'd be turn'in 120hp and 130tq? Something like that?

(IMG:style_emoticons/default/driving.gif)

[ChrisFoley]

Without stabbing gabs of financial resources in a T-4 engine, reving it much past 5000rpms won't do much becuase of the law of diminishing return.

(IMG:style_emoticons/default/confused24.gif)
With the right cam, etc. there is plenty of power to be had above 5000 rpm, and it doesn't necessarily require gobs of cash.
My dd currently has a 1.7L that happily revs to at least 6200rpm and makes excellent power up there.

Another engine I have for my race car revs to 6800 and uses HD single springs.
However, it has lighter than stock valves and ceramic lifters to lighten the valvetrain.

There's nothing magical about 5250. Its about a simple mathematical relationship.
An engine's torque curve and horsepower curve always cross at that rpm (when the y axis units are the same). In other words, torque in lb-ft at 5250 rpm equals HP at 5250 rpm, always.
It doesn't have anything to do with the rpm that peak torque or HP occurs at with a particular engine.

[gothspeed]

Thanks for all the responses (IMG:style_emoticons/default/smile.gif)! Though more are certainly welcome (IMG:style_emoticons/default/biggrin.gif)!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If it were me I'd shoot for 9:1 compression and run premium fuel. Compression is an easy way to get power, and a 2056 loves 9:1 compression with carbs and that cam. Dunno what the rev range would be with single HD springs. I assume that HD is stiffer then stock?

Zach

Thanks for the heads up! I will look into what I need to do to get 9:1 without custom pistons. Yeah the single HD springs are supposed to be a tad stiffer than stock. The reason I am even concerned about my valve springs is because the 44/38 valves are a little bigger than standard 2.0 and thus a little heavier.

I don't think it's going to gain anything from revving that high as horsepower drops off after 5500. I have a 2056 with 9:1 compression and dJet and heavy springs and retainers. It just beefs up the valve train a little.

Thanks! Though the 494 cam has a little more duration and lift than a stock D-jet cam and should extend the RPM TQ range a little further. Also when running dual carbs the intake runners are a little shorter, which is also conducive to raising the TQ to a slightly higher RPM.

TQ magic RPM to remember is 5250 and of course it's been hashed a million times over, TQ=Acceleration, HP=Top Speed (most of the time).

Without stabbing gabs of financial resources in a T-4 engine, reving it much past 5000rpms won't do much because of the law of diminishing return.

Use to be higher comp|ratio was the cheap and easy way to get that TQ number up. Gas today doesn't really support it without knock sensors etc.

(IMG:style_emoticons/default/agree.gif)

People are giving you sound advice.

When I go through mine, it'll probably be 9:1, Jakes cam kit for FI and mildy cleaned up ports on the heads. I figure with my L-Jet (Gonna probably have to get those 187cc injectors), I'd be turn'in 120hp and 130tq? Something like that?

(IMG:style_emoticons/default/driving.gif)

I do like the 9:1 compression idea and will try to get there without spending too much (IMG:style_emoticons/default/smile.gif). Jake's cam kits look great, though I could not find any info on the lift/duration/overlap specs of his cam kits.

Without stabbing gabs of financial resources in a T-4 engine, reving it much past 5000rpms won't do much becuase of the law of diminishing return.

(IMG:style_emoticons/default/confused24.gif)
With the right cam, etc. there is plenty of power to be had above 5000 rpm, and it doesn't necessarily require gobs of cash.
My dd currently has a 1.7L that happily revs to at least 6200rpm and makes excellent power up there.

Another engine I have for my race car revs to 6800 and uses HD single springs.
However, it has lighter than stock valves and ceramic lifters to lighten the valvetrain.

There's nothing magical about 5250. Its about a simple mathematical relationship.
An engine's torque curve and horsepower curve always cross at that rpm (when the y axis units are the same). In other words, torque in lb-ft at 5250 rpm equals HP at 5250 rpm, always.
It doesn't have anything to do with the rpm that peak torque or HP occurs at with a particular engine.

Absolutely correct! That 5252 number is how HP is determined from torque (IMG:style_emoticons/default/smile.gif)

TQ x RPM / 5252 = HP

I want to stay under 6.5k RPM most likely will stay just under 6k RPM, which is why I chose a semi modest overlap cam (280°) ....... I know the 86a web cam (290°) will keep pulling beyond what single HD springs could handle and actually further than I care to take my little motor (IMG:style_emoticons/default/ohmy.gif)

According to your race motor (6800RPM) it looks like 6k RPM should be do-able with single HD springs on my motor (IMG:style_emoticons/default/smile.gif)!! I will also try to lighten the valve-train where possible without weakening it . Thank you for sharing your 'first hand' experience on the RPM ranges of your motors (IMG:style_emoticons/default/biggrin.gif)!!!

[Jake Raby]

The web 494 is 288*@ .020, the numbers on that cam have been incorrect from Web for YEARS.

The 494 straight pattern cam with 8.8:1 and 44X36 valves is done making power at 6K unless the heads have decent sized ports.

Also th standard 44mm intake valve is fairly heavy, single springs probably aren't going to control it past 6500 RPM without lofting..

The ramp rate of the 494 is greater than that of an 86A and thats hardder on springs, valve springs and etc.. If my memory serves me correct Chric used the 86A with his single springs.

Do more homework, the 494 is a good cam, but the desires that you have aren't exactly what the characteristics of this cam generally fill. I probably have 200 engines running the Web 494 and probably 200 more with a hybrid dervative of that profile. I drove my car 160,000 miles with one of those installed and it had 44X36 valves..

[gothspeed]

Thanks for chimming in Snake Oil! More than likely I will stay just under 6k RPM. I just want to know that my larger/heavier valves are not gonna kiss my pistons and or slam on the seats with single HD springs. I have no other issue with dual valve springs other than the increased tension being put onto the factory rockershaft studs.

True, the shorter duration and higher lift of the 494 vs the 86a shoots the valve up/down quicker. But the improved bottom end of the 494 sounds kinda nice.

I would love to use the 86a but I am not certain how much bottom end/response it will lose. The increased top end power however, will of course be very welcome (IMG:style_emoticons/default/smile.gif).

The car will NOT be used for autocross or short courses but rather on freeway ramps/off ramps, long winding mountain roads and open highways ..... and if the 86a suits that better, I am not against it!!! (IMG:style_emoticons/default/sunglasses.gif)

[Jake Raby]

Dual springs increase oil temperatures a notable amount and thats due to the friction from the inner and outer springs rubbing together.

Remember, the 494 is really 288@20 not 280 as advertised, so the 86A is very similar. I have master information for each and have also ran them all in the cam doctor.

I have swapped between an 86A and 494 in the same engine, as a straight pattern cam off the shelf the 86A was a better cam all around to include cabin noise and MPG.

The descriptions from the cam grinder mean very little, the cam may or may not respond to the rest of the engine's combination as described.

Cam grinders are not engine builders. Its all in the combo.

[gothspeed]

I have done more research and still think the Web Cam 494 (288° duration and .465" lift is the way I will be going. If that is too big, then the European Motorworks 'E' cam is just a tad milder (280° duration and .430" lift).

The only reason to go milder is to reduce stress on the valvetrain and I am thinking my larger valves would make up for the flow loss of not using the 494. With either cam scenario, I was encouraged to go with dual valve springs by the machine shop. Not what I wanted to hear but they build and repair a lot more of these little motors than I do.

Tentative math shows I can get pretty close to the target 9:1 compression by playing with cylinder shims/head gaskets thickness or lack thereof and still clear the valve pockets at TDC/overlap by a reasonable margin. Of course the rocker geometry will have to be redone with proper length chromoly push rods.

[Jake Raby]

The biggest gripe I'd have with the 494 is the very loud intake note that you'll end up with when coupled to carbs..

The cam also has a very fast ramp, so ensure you get it ground on the largest base circle possible, else you'll have lifter bore wear and you'll end up with more valvetrain clatter.

Don't spring it to kill it.

[Brett W]

You want the 163/86B. Take my word for it, you will love that cam. Run 44s with 32-34mm vents and you will have good bottom end. Make sure the heads can support the valve sizes. You will want 9.5+ on the compression. Have the cam cut on a 104 centerline. Might also look at a +5. You will have to run a dual spring to get the proper revs, but the engine will spin to 7200+ with no problems and good reliability. You might want to look at getting the springs coated, but I don't know if it will help that much. Get a Mallory Dizzy. The header will also help you. Remember the bigger intake will not help you keep the velocity up in the lower revs but it will come on like a raped ape up high. I would leave the 42 in there and put a good valve job on it and use nicely contoured valves. Also look at using TI retainers it will help keep the valvetrain safer for the extra rpm. The solid spacer kit is nice but it will need to be tailored to your application otherwise it will make noise at idle. Also Custom pushrods are in your future, as are swivel foot adjusters. This will also call for custom pistons and cylinders. Order Pistons and have RIMCO bore your cylinders to each piston. Also the deck height will probably need to be adjusted. The case could stand a few oiling system mods and those should all be done to help support the rest of the system.

You are probably better off buying a kit from Jake. AS you can see the one little change you propose has affected the whole engine. Everything associated with that system will have to be re-engineered to make that one change work properly. Otherwise you will have a poor running engine. To do it right won't be a cheap affair, but to do it right will pay off in the long run with a strong and durable engine that last for years.



Ok, now that I have created the world's longest sentence...............

[ChrisFoley]

... a strong and durable engine that you only use once.

(IMG:style_emoticons/default/blink.gif)

[ChrisFoley]

My vote is for the 86A. 9.5+ comp.
Shimmed single HD springs with Ti retainers and 6200 redline. Should be safe to 6500 rpm.

[Brett W]

OH brain fade there. Must have been distracted when I was writing that.

[gothspeed]

Thank you for the info Racer Chris!!! I do like the 86a character and since I will NOT be doing auto-cross, I would much prefer to have top end power in exchange for bottom end grunt.

From what I understand the 86a will do that. The larger valve seats (44 & 38) have already been installed and I have done most of the 'port to seat' matching last night. If you think I can stay with Single HD springs with the heavier valves to 6k without floating, I am all for it (IMG:style_emoticons/default/smile.gif)!

I am working on getting the most compression as possible with the pistons I have and am fairly confident of about 9:1 ish. Though I will keep working to eek it higher.

If I have to go dual springs than I might as well go to an 86b cam (.500 lift and .300° duration) ... lol (IMG:style_emoticons/default/biggrin.gif)

[Brett W]

Don't expect the single spring to control the heavy steel intake valve. Made that mistake. It floats the valves at 5800 rpm. I would look hard at the cam I listed, if nothing else, advance the cam to move the power band down to where you want to use it. You would however be surprised how quickly 6K will come up. Its nice to have that extra power band. Go with the 163 86B, it is the best of both worlds.

[HAM Inc]

For the revs you outlined the 42's would have been the better choice. For the limited revs that single springs will control the 44's are to much valve. You will have much fuel seperation in the area beneath the valve at anything but high revs. At cruising speed the fall out will be severe. Meaning the engine will be harder to tune. The 38mm exhaust are bigger than is required until large displacements and/or high revs are the order.

As Jake stated in an earlier post the 494 has a fast ramp. I have a pair of heads in the shop right now that have 44's and dual springs that were installed on a 494 cam. The cam shows evidence of valve loft, despite the owners insistence that he didn't turn it more than 6500.

Hope it works out for you, but your combo is already compromised by your valve choice. You could always up the compression, install dual springs and keep it turning. That would better suit the valve choice you have made.

[gothspeed]

Thanks for the note Brett. I think you convinced me into going with dual springs, it will indeed give me more cam profile options. I will also make sure the valve component travel is configured to accommodate a higher lift, just in case (IMG:style_emoticons/default/wink.gif)

As I have mentioned before, I would much prefer to gain higher RPM power over lower RPM grunt. So dual springs falls in line with that direction (IMG:style_emoticons/default/smile.gif)

Ham thanks for the info. Though with all due respect, fuel separation 'at cruise' is caused by more than just large valves or slow port velocities. Another big contributor is a long overlap cam, which does not create a good intake manifold vacuum 'at cruise speeds'. Higher vacuum vaporizes fuel or any liquid for that matter. That is why boiling points of liquids are progressively lower at higher altitudes.

Another issue that high overlap cams have at 'part throttle', is the exhaust gasses are slowed a bit. This is due to the higher pressure exhaust making its way towards the intake during an extended overlap period.

Thanks for posting guys (IMG:style_emoticons/default/pray.gif) !!!! Please continue to post any experience with the 2056 in various carb/high performance configurations (IMG:style_emoticons/default/smile.gif)

[HAM Inc]

Ham thanks for the info. Though with all due respect, fuel separation 'at cruise' is caused by more than just large valves or slow port velocities. Another big contributor is a long overlap cam, which does not create a good intake manifold vacuum 'at cruise speeds'. Higher vacuum vaporizes fuel or any liquid for that matter. That is why boiling points of liquids are progressively lower at higher altitudes.

Yep. That is correct. And that is why a cam that reads like a big cam on a 2056 will read like a small cam on a 2550.

The cam options that have been bandied about on this thread are long enough and have enough overlap for a 2056 to have sluggish port velocity in the vicinity of the intake valves at part throttle. That's why I mentioned bumping the compression and turning it up. And since it sounds like you want this baby to run at higher revs that should work for you. Those valve sizes will really breath a 2056 and support some serious revs! But you will need springs for it.

Looking at the other extreme, a 2056 with 1.7 heads prepped with 40mm intakes and 34mm ex would make a great bottom-end engine and cruise great with good mileage. Would get by with single springs as it wouldn't have enough top-end power to need duals.

That's one of the things I love about the T4 there are many options available to ensure that everyone gets what they want. (IMG:style_emoticons/default/beerchug.gif)