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]

So the engine theme is settled (IMG:style_emoticons/default/smile.gif)!

Looks like I will be going with bigger cam, dual springs, higher compression and higher revs (IMG:style_emoticons/default/smile.gif)!!! I may have to make custom pistons to go above 9:1. But if it will give me a little fire breathing monster at higher revs, it will be worth it!! (IMG:style_emoticons/default/biggrin.gif)

I was looking at the 163/86B split lift/duration recommended by Brett and the shorter intake duration should improve the bottom end over the straight 86b. I will take more measurements and see if I can hit a solid 'static' 9.5:1 compression with my exisitng pistons.

[VaccaRabite]

KB 96mm flat topped pistons. You do not need to move the cylinders much at all to jump the compression.

Zach

[Brett W]

Yeah flat top KB 96mm pistons with a .040 piston to deck clearance will work well. Cut the heads down to shrink the combustion chambers down. The bigger the cam the more compression you can run (within reason). Shoot for 9.5 or higher to make the cam really work right. It will give good bottom end if done right. Since it is a street car go with the smaller venturies on the carb to help keep the velocity up. What you gain in the midrange will greatly offset the minuscule loss on the top end. The system has to be carefully considered.

[gothspeed]

KB 96mm flat topped pistons. You do not need to move the cylinders much at all to jump the compression.

Zach

Yeah flat top KB 96mm pistons with a .040 piston to deck clearance will work well. Cut the heads down to shrink the combustion chambers down. The bigger the cam the more compression you can run (within reason). Shoot for 9.5 or higher to make the cam really work right. It will give good bottom end if done right. Since it is a street car go with the smaller venturies on the carb to help keep the velocity up. What you gain in the midrange will greatly offset the minuscule loss on the top end. The system has to be carefully considered.

Makes sense (IMG:style_emoticons/default/smile.gif)!! I have a a nice flat top set with very shallow valve reliefs. I will measure them to see how manys CCs the valve pockets are. I will probably not use a head gasket and slightly cut the heads to reduce chamber volume. Of course keeping a nominal deck height to prevent any interference.

I believe the 2.0 combustion chamber is about 60cc. Using that as a reference and using rudimentary math, if I get it down to 55cc with fly-cutting, I will get a tad bit higher than 9:1. Higher compression calculations and CC measurements will be worked out more accurately after I install the valves. However I am getting a set of 44mm IDF webers ASAP (IMG:style_emoticons/default/biggrin.gif)!!!!

Using dual valve springs, 44mm intake/38mm exhaust valves, higher RPM power 'target' and much discussion on this thread (thanks guys!!!) ....... thus far my cam choices are now as follows:

web

86b ---------- .500" lift and 300° duration

163/86b ----- .500" lift and 284°/300° duration (split cam)

163 ---------- .500" lift and 284° duration

EMW

T-4H --------- .488" lift and 286° duration

T-4II --------- .475" lift and 281° duration

T-4J ---------- .500" lift and 307° duration

[0396]

mmm great info

[VaccaRabite]

Please, don't just set deck height at .040 and call it a day.

measure the CC of your heads and calculate what you WANT your height to be based on the target compression ratio.

My heads were 55 CC. If I had assumed 60CC my compression would have gone very much off from my desired 9:1.

Find a web based CR calc, and plug in your metrics (I actually have a sweet little app on my iPhone for it). Don't guess on your deck height and CR, KNOW it.

Zach

[ChrisFoley]

EMW

T-4H --------- .488" lift and 286° duration

T-4II --------- .475" lift and 281° duration

T-4J ---------- .500" lift and 307° duration

The J grind cam makes for an engine that isn't very streetable in my opinion.
I had a 2.2L short stroke engine with one that made awesome power to over 7K rpm but had trouble leaving a stop light unless I revved it to 4500 and dumped the clutch. (The 48mm intake valves had something to do with that I suppose. (IMG:style_emoticons/default/rolleyes.gif) )

[HAM Inc]

Most un-cut 2.0 914 heads fall in the 58-60cc range.

A .010" flycut removes ~ 1.4cc's.

[Brett W]

What ever you do keep the piston to deck height to .040 or slightly less. .040 is a safe number that I would go no higher than. You can run lower but I don't advise that unless you have very tight control over you piston to wall clearance. The KB 96mm pistons can run pretty tight clearances because they don't tend to grow like the Forged pistons. Great for ring life and noise. The higher the deck height you run the less efficient the chamber will be.You should also check the combustion chamber fit to the cylinders and make sure you have no sharp edges overlapping into the cylinders. Don't use headgaskets, throw them away now.

I would cut the heads down to 55 or less. That will help the compression. You need as much compression as you can get. You can't get too much with the flat top pistons. True the tops and bottoms of the cylinders on a lathe and set your deck heights with the small shims under the bottom of the cylinder. Also true the block deck as well. You want the cylinder as straight as possible.

Are you doing port work?

[gothspeed]

Check on the deck height, cylinder true check and no head gaskets (IMG:style_emoticons/default/smile.gif). I have already marked the mating interface of the cylinder to head and have removed the offending material. The flow path to the valves is smooth and obstruction free. I have even lightly 'unshrouded' the valves to improve flow on the valve/head area near the cylinder walls. I did not remove too much, as I need some of that for compression purposes (IMG:style_emoticons/default/wink.gif). I will also radius the bottom edge of the exhaust valves to minimise any potential 'hot spots' and to improve flow around the valve bottom and into the exhaust port.


I am doing very modest port work because I like to keep port velocities on the higher side. This being a smaller 2056 motor, it shouldn't need huge ports. Mostly getting rid of casting imperfections and leaving a nice 'sanded' finish to create tiny surface vortices to improve fuel atomisation. Also the intake manifolds inherent 'funnel like' taper should accelerate the A/F mixture nicely into the port. The manifolds will get the same surface treatment and port matching when I get them.


The stock 2.0 intake port diameters are around 35mm and after the current work should measure just under 36mm. Which is roughly a 5-6% increase in cross-sectional flow area. I may go bigger but this is where I am at thus far, more number crunching regarding port size will be done taking various cam profiles and RPM ranges into account. Removing material is easier than putting it back on (IMG:style_emoticons/default/wink.gif)

[brer]

true the cylinders on a lathe? I won't say don't do it, but I wouldn't.

[gothspeed]

true the cylinders on a lathe? I won't say don't do it, but I wouldn't.

I don't really do not want to discuss 'methods' on this thread, as everyone has their own way of doing things and it drives many threads 'off topic'. A lathe is more than likely an extreme case and I have never done it. However there are numerous ways to remove imperfections. The cylinders are probably not too bad and may only need lapping at worst (IMG:style_emoticons/default/wink.gif).

[brer]

some people have access to really expensive tools too! I know this well, particularly after reading this forum for a few years.

I'm constantly amazed at the stuff that is created and posted here. Bookmarked and looking forward to hearing how your build goes

[gothspeed]

some people have access to really expensive tools too! I know this well, particularly after reading this forum for a few years.

I'm constantly amazed at the stuff that is created and posted here. Bookmarked and looking forward to hearing how your build goes

Thanks for your input, I agree, there is indeed a wide spectrum of experience, knowledge, abilities and machine capabilities on this forum (IMG:style_emoticons/default/smile.gif)! That is why I queried for some first hand experience on here. (IMG:style_emoticons/default/smile.gif)

I will measure everything I can, to avoid common pitfalls. I wish I had a bigger budget for this build, but the dough designated for this project has to be spread across the GT flare install, body work, paint, brakes, suspension, gearbox, electrical, wheels/tires, interior and finally this little engine. With the current budget, there is no way this project is even gonna come close to what I would like to do on this little car, but that is not gonna stop me from trying to get a decent result!!! (IMG:style_emoticons/default/smile.gif)

Since I am going with dual springs, the 86a is still in the running as a possible cam, depending on how it would fit into this configuration and its RPM/torque limits.

[Brett W]

If you do an 86A do an 86A/86A+5 or +10 on the exhaust side.

If you have a mandrel that can locate off the center bore of the cylinder and are using a the chinese cylinders, you most definitely need to verify the cylinder tops and bottoms are square.

I did my cylinders and was impressed with how crooked they were and how far off each cylinder was compared to the rest for deck height. I used some custom shims on the bottom of the cylinders to set the deck height to the proper clearance for my specifications. Are you having RIMCO bore your cylinders? They can perform this operation for only a few bucks more.

[gothspeed]

If you do an 86A do an 86A/86A+5 or +10 on the exhaust side.

If you have a mandrel that can locate off the center bore of the cylinder and are using a the chinese cylinders, you most definitely need to verify the cylinder tops and bottoms are square.

I did my cylinders and was impressed with how crooked they were and how far off each cylinder was compared to the rest for deck height. I used some custom shims on the bottom of the cylinders to set the deck height to the proper clearance for my specifications. Are you having RIMCO bore your cylinders? They can perform this operation for only a few bucks more.

How is the +5 or +10 done? Do they just grind .005" or .010" material off the 'base circle' opposite the lobe?

I will check the cylinders on a 96mm rotary mandrel with some dial indicators before I start cutting material off the heads, as this will affect my deck height should the cylinders need serious truing.

[Jake Raby]

Don't judge those cams simply by their .020 and .050 numbers.. To really understand the numbers you need to see what the duration is at .200-.350" lift.

If you consider those numbers some cams magically appear much larger than they used to when you just looked at the advertised numbers. Choosing a cam from just those numbers isn't illustrating the big picture.

FYI- The cam in Len's FP engine that spins 8,500 RPM is actually smaller than all but one of the cams you mentioned if one looks at onl the advertised numbers, thats in a full race engine with 13:1 CR.

The difference is that cam is HUGE between .175-.410" lift. Lots goes into camshaft selection, you can't really make the best choice until you have actual flow numbers from the heads.

[HAM Inc]

Don't judge those cams simply by their .020 and .050 numbers.. To really understand the numbers you need to see what the duration is at .200-.350" lift.

Amen! I've been trying to help folks understand that for years, but sometimes (not always) it's like talking to Nigel from Spinal Tap. "but this one goes up to 11!"

Lots goes into camshaft selection, you can't really make the best choice until you have actual flow numbers from the heads.

Yep. That's why I have spent countless hours on the flow bench and Jake has spent countless hours pouring over the flow data and testing cams on the dyno and the street and the track.

And I'll take Jakes statement one step further. You can't accurately port a head until you have base-line data. Years of experience make it possible to sight out obvious problem areas for improvement, but until you know the ex/in flow ratio an educated approach is not possible. And screwing-up the flow ratio bad enough may dictate the need for a special cam grind. Getting off just a few % can lead to an engine with performance characteristics different from that desired.
The intended use for the vehicle the engine is going in is the single biggest factor I consider when choosing a flow ratio. It is very important!

No shameless plug for our businesses intended there, just some info.

[Kansas 914]

it's like talking to Nigel from Spinal Tap. "but this one goes up to 11!"

(IMG:style_emoticons/default/av-943.gif)

Great analogy!

[Brett W]

I was trying not to confuse the OP with ramp rates, and flank characteristics, it is sometimes hard enough to explain to the average person duration and lobe separation. Jake and Len are spot on with the characteristics of camshafts.

Head work will radically affect camshaft requirements. Not really sure what your plans and experience with the T4 head is but be careful just hogging out the ports.

It might pay to offer Len a little something to pick his brain. Could be money well spent.