N/A Build! Need Assistance

[AE Harold.]

Ive been told that in order to make great power with 4age and itbs you'll need to run a high compression.

That's like saying to be a really fast running you need good shoes. It's part of the equation but without the rest done properly it's useless. People who say things like that likely don't know what they are talking about. How much compression you can run is completely dependent on the cams. How much power they make depends on many other things. If it's not all addressed together you will have a much lower chance of being happy with the build.

I differ slightly... it isn't necessarily part of the equation! ITBs don't automatically mean more power. They are a type of induction system, that is all... my 145whp engine, and yoshi's client both use single throttle bodies, and both of us are making 40%+ more power then stock!!!

The rest of what yoshi's says is pretty accurate.

One word of warning about ITBs... they are notorious for being improperly set up (synchronized - both mechanically, as well as vacuum) causing many people who have them, SERIOUS drive-ability issues.

I know ITBS don't automatically mean more power. I personally love the use of itbs. My 20v itbs have already been rebuilt, synchronized, and tested to make sure all four throttle bodies are set correctly.
The kelford cams 193b cams are what I'm leaning towards too since I'm planning on running an after engine management system.

[oldeskewltoy]

My 20v itbs have already been rebuilt, synchronized, and tested to make sure all four throttle bodies are set correctly.

Do tell? ITB's are set while on a running engine, they may have been rebuilt... the other stuff... needs to be completely re-checked, re-set once you install these on your engine.

[yoshimitsuspeed]

I differ slightly... it isn't necessarily part of the equation! ITBs don't automatically mean more power.

I guess I wasn't clear.
I meant that compression is part of the equation but needs to be factored along with a number of other things.
I agree for the most part that ITBs aren't a vital part of a build until you get to very high power levels and even then you are talking about very small improvements over a properly sized single TB.

[burdickjp]

Let's talk about trapped volume. Trapped volume is the volume in the cylinder when the intake valve closes. It is much of the reason why you need to increase static compression when going for larger cams, and why small cams and high static compression can be problematic.

On an AE92 (smallport, high comp) engine the intake valve closes 44 degrees after bottom dead center. With a stock compression ratio of 10.3:1 the cylinder volume at that angular position is approximately 393cc.
The ratio of the trapped volume to the compressed volume is 10.8:1.

With Kelford's 193-B camshafts the intake valve closes 46 degrees after bottom dead center. With a stock compression ratio the cylinder has a volume of 389cc.
The ratio of the trapped volume to the compressed volume is 10.7:1.

What would the static compression ratio need to be for the trapped volume compression ratio at 46 degrees to be 10.8:1? It's not much, only 10.4:1.

But wait. There's more.

The highest performance naturally aspirated 4A-G is the AE111 (blacktop 20v). Let's look at that.

The static compression ratio is a happy 11:1. The intake valve closes 40 degrees after bottom dead center. At that angular position the trapped volume is 397cc and the compression ratio is 11.77:1.

To achieve that with the 193-B camshafts, on the 16v, of course, you'd need a static compression ratio of about 11.3:1. To get that, you'd need a compressed volume of about 32.77cc. There's a goal for your chamber and piston work.

Someone else check my math, please.

[oldeskewltoy]

Let's talk about trapped volume. Trapped volume is the volume in the cylinder when the intake valve closes. It is much of the reason why you need to increase static compression when going for larger cams, and why small cams and high static compression can be problematic.

On an AE92 (smallport, high comp) engine the intake valve closes 44 degrees after bottom dead center. With a stock compression ratio of 10.3:1 the cylinder volume at that angular position is approximately 393cc.
The ratio of the trapped volume to the compressed volume is 10.8:1.

With Kelford's 193-B camshafts the intake valve closes 46 degrees after bottom dead center. With a stock compression ratio the cylinder has a volume of 389cc.
The ratio of the trapped volume to the compressed volume is 10.7:1.

What would the static compression ratio need to be for the trapped volume compression ratio at 46 degrees to be 10.8:1? It's not much, only 10.4:1.

But wait. There's more.

The highest performance naturally aspirated 4A-G is the AE111 (blacktop 20v). Let's look at that.

The static compression ratio is a happy 11:1. The intake valve closes 40 degrees after bottom dead center. At that angular position the trapped volume is 397cc and the compression ratio is 11.77:1.

To achieve that with the 193-B camshafts, on the 16v, of course, you'd need a static compression ratio of about 11.3:1. To get that, you'd need a compressed volume of about 32.77cc. There's a goal for your chamber and piston work.

Someone else check my math, please.

Not your math... but your variables... from memory the stock cams cam timing is seat to seat, while almost all the others show cam timing to be at either .040, or .050 of lift... NOT seat to seat. I believe you can get seat to seat measurements on the HKS cams....

For your purposes... the earlier cams have a .040 duration of 204, while the later cams have a .040" duration of 198. Also... the later cams have slightly offset timing, as compared to the earlier cams....

[burdickjp]

Not your math... but your variables... from memory the stock cams cam timing is seat to seat, while almost all the others show cam timing to be at either .040, or .050 of lift... NOT seat to seat.

I did, in fact, grab the wrong number for the 193-Bs. Tomei cam cards include seat-to-seat numbers, Kelford advertises those numbers as 1mm of lift. I confused the two. My mistake.
I thought Kelfords closing number looked a little strange, but didn't catch the "@ 1mm lift" on the card. This is why we have peer review

I, unfortunately, do not have seat-to-seat numbers for Kelfords 193 range, only their 194 range (because 20v). I'll email Kelford and get the seat-to-seat specs for their 193 line.

[yoshimitsuspeed]

Let's talk about trapped volume. Trapped volume is the volume in the cylinder when the intake valve closes. It is much of the reason why you need to increase static compression when going for larger cams, and why small cams and high static compression can be problematic.

On an AE92 (smallport, high comp) engine the intake valve closes 44 degrees after bottom dead center. With a stock compression ratio of 10.3:1 the cylinder volume at that angular position is approximately 393cc.
The ratio of the trapped volume to the compressed volume is 10.8:1.

With Kelford's 193-B camshafts the intake valve closes 46 degrees after bottom dead center. With a stock compression ratio the cylinder has a volume of 389cc.
The ratio of the trapped volume to the compressed volume is 10.7:1.

What would the static compression ratio need to be for the trapped volume compression ratio at 46 degrees to be 10.8:1? It's not much, only 10.4:1.

But wait. There's more.

The highest performance naturally aspirated 4A-G is the AE111 (blacktop 20v). Let's look at that.

The static compression ratio is a happy 11:1. The intake valve closes 40 degrees after bottom dead center. At that angular position the trapped volume is 397cc and the compression ratio is 11.77:1.

To achieve that with the 193-B camshafts, on the 16v, of course, you'd need a static compression ratio of about 11.3:1. To get that, you'd need a compressed volume of about 32.77cc. There's a goal for your chamber and piston work.

Someone else check my math, please.

How are you coming to a higher compression ratio with a lower trapped volume?
The BT would have to have 4.5CCs dome to hit 11:1 compression. That would give it a compressed volume of 33.3 cc plus the volume of the HG. That should total about 40 cc.
440 cc / 40 cc is 11:1.
I'm not sure if your calculation factored for the additional compressed volume in the head or not so I'll do both.

397 / 40 would be 9.925
397+40 = 437 / 40 = 10.925.

DCR will always be lower than SCR.

The problem is that this calculation only applies to a motor at a theoretical 0 RPM.
As the motor starts spinning cylinder filling will be directly related to VE and the VE can be vastly different than that. People call it dynamic compression ratio which really pisses me off because there is nothing dynamic abut it. It tells you nothing about how the motor will behave at RPM.
It kind of gives you a redneck way of kind of guessing what it might behave like because a bigger cam will tend to have a lower DCR and will tend to have lower compression at lower RPM where detonation is more likely but it is no more than that.
You could have two motors with two different cams and or intake, exhaust etc that both have a 10:1 DCR but at 3000 RPM one might have a VE of 60% and one could have a VE of 90%.
This is why I think DCR should be banned from automotive technical vocabulary.

[burdickjp]

How are you coming to a higher compression ratio with a lower trapped volume?
The BT would have to have 4.5CCs dome to hit 11:1 compression. That would give it a compressed volume of 33.3 cc plus the volume of the HG. That should total about 40 cc.
440 cc / 40 cc is 11:1.
I'm not sure if your calculation factored for the additional compressed volume in the head or not so I'll do both.

397 / 40 would be 9.925
397+40 = 437 / 40 = 10.925.

DCR will always be lower than SCR.

The problem is that this calculation only applies to a motor at a theoretical 0 RPM.
As the motor starts spinning cylinder filling will be directly related to VE and the VE can be vastly different than that. People call it dynamic compression ratio which really pisses me off because there is nothing dynamic abut it. It tells you nothing about how the motor will behave at RPM.
It kind of gives you a redneck way of kind of guessing what it might behave like because a bigger cam will tend to have a lower DCR and will tend to have lower compression at lower RPM where detonation is more likely but it is no more than that.
You could have two motors with two different cams and or intake, exhaust etc that both have a 10:1 DCR but at 3000 RPM one might have a VE of 60% and one could have a VE of 90%.
This is why I think DCR should be banned from automotive technical vocabulary.

Yeah. Lesson in process: Vette your tools before posting. I'm trying a new method of working with tabulated data (pyspread), and paying more attention to it than the numbers it's spitting out. It wasn't working correctly when I put in numbers for 194-C cams, so something is up. I'll tak. a look when I get back from breakfast. We'll come to a good conclusion eventually.

The process, though, is not just some hick way of doing things. If you don't like people calling it dynamic compression (which makes no sense) then don't call it that. Blair calls it trapped volume, and that makes sense.

I'll post up the formulas and cite their sources when I get back.

[oldeskewltoy]

where detonation is more likely

first... it doesn't matter who said it.... (in other words...not attacking yoshi )

This is where theory hits reality...

until you put gas in it... and run it... you really won't know


now as to DCR or trapped volume... what it is called really doesn't matter...


oh and yoshi... can you be a bit less condescending?? (redneck... REALLY???) IF you have something to say... stop being "FOX NEWS" about it, and just report information...

[AE Harold.]

So is it best to build with seat to seat cams such as the poncams rather than the kelford 193-B cams?

[yoshimitsuspeed]

The process, though, is not just some hick way of doing things. If you don't like people calling it dynamic compression (which makes no sense) then don't call it that. Blair calls it trapped volume, and that makes sense.

I'll post up the formulas and cite their sources when I get back.

It doesn't change the fact that it is useless when it comes to calculating trapped volume in a motor that is actually spinning.
If you are trying to calculate at a theoretical zero RPM then it could be useful information.

[burdickjp]

It doesn't change the fact that it is useless when it comes to calculating trapped volume in a motor that is actually spinning.
If you are trying to calculate at a theoretical zero RPM then it could be useful information.

Volume is determined by the geometry of the engine and nothing else. The engine could be spinning at 100 RPM, 1 000 RPM or 10 000 RPM and the trapped volume would not change.

Mass, on the other hand, is harder to nail down. Even so, the mass you have at combustion is just the density of the trapped volume.

Kevin @ Kelford says IVC at 0.001" (he must think I work in inches because I'm a yank) is 61 degrees after bottom dead center. With smallport compression that's a trapped volume of 319 cm^3 and a trapped compression ratio of 8.47:1.

To get that back up to the original trapped compression of 9.35:1 you can opt for an 11.4:1 swept compression ratio, requiring a 38.15 cm^3 compressed volume.

To achieve the AE111 trapped compression ratio of 10.15:1 would require a swept compression of 12.4:1 and a 34.8 cm^3 compressed volume.

[yoshimitsuspeed]

Volume is determined by the geometry of the engine and nothing else. The engine could be spinning at 100 RPM, 1 000 RPM or 10 000 RPM and the trapped volume would not change.

I phrased that wrong. You are right, the trapped volume doesn't change but it is completely useless information unless all of the other variables are filled in. Even then the other variables would make it easier to solve without taking the extra steps trying to solve for density when the valve closes.
After all like you said what's really important is density right?
Even static compression ratio doesn't mean anything in a moving motor except that it's a great way to set your baseline that everything else is based off of. From it we know total cyl volume, stroke displacement and compressed volume.
SCR doesn't tell us anything about how the motor will perform. After all it's pressure and density that is important.
Let's say that all other variables like fuel, timing, etc are fixed. 4AGE engine with 400cc cyl. Let's say that a motor makes peak power at 150 PSIA compression and gets detonation at 151 PSIA. Let's say the motor has a 10:1 SCR. And Lets say you have a cam that closes at BDC.
This also reminds me that all pressure values need to be calculated based off absolute which I did not do in my calculations above.
Now let's say you have a really bad cam/mani combo that leaves 5 PSIA in the cylinder when the valve closes. Now at 10:1 compression at TDC you will have 50 PSIA. This is a long way from where you want to be. The motor has a really crappy VE and really bad compression pressure even though it has the biggest trapped volume it can.

Now let's say you throw in a really big cam that closes 90 deg ABDC. Now your trapped volume is 200cc.
But now let's say that at the same RPM the motor has 100% VE. VE is calculated off the total volume of the cylinder so now we have what would be 400cc of air at atmospheric pressure in the cylinder. This is enough to make our calculations off of but if you wanted to take the extra step of calculating trapped volume you would have to calculate what that pressure would be if stuffed into 200cc. Fortunately right now that is an easy calculation. So now we have 29.2 PSI at 200CC.

Using VE and SCR it's easy to calculate that your final pressure will be 147 PSI.
Using trapped volume you have to double the pressure then half the trapped volume to come to the same result.
In the end trapped volume just adds steps to the process and doesn't tell you anything you couldn't have figured out without it. Without knowing VE or knowing temp and pressure at IVC trapped volume doesn't give you any useful information.

[burdickjp]

Even static compression ratio doesn't mean anything in a moving motor except that it's a great way to set your baseline that everything else is based off of. From it we know total cyl volume, stroke displacement and compressed volume.

I'm not sure how you are getting any of that information from the static compression ratio.

Static compression ratio is but one number among many to describe what's going on with an engine. There's also delivery ratio, trapping efficiency, delivery efficiency, and a whole cornucopia of other ways to look at it. It's not special, and doesn't really tell you much.
Most of the generalities associated with the static compression ratio are the product of static compression with the respectively appropriate valve timing.

After all it's pressure and density that is important.

Everything is secondary to the mass in the cylinder when the intake valve closes. Since that's a volume, you can calculate density or specific volume if you'd like.

VE is calculated off the total volume of the cylinder

VE is actually calculated as the mass of air delivered through the intake valve with respect to a mass of air equivalent to the swept volume (not total volume) at ideal density (SAE J604). While called volumetric efficiency, it is not a ratio of any volume, but of mass.

I think trapped compression ratio is useful in this specific conversation in illustrating in some respect the relationship between valve timing and compression ratio.

ANY calculation done considering the swept volume, or full volume, can also be considered with the trapped volume, reaching similar conclusions.

I have absolutely no idea where you were trying to go with your example. I'm just going to say you aren't close enough to even be wrong here.

[yoshimitsuspeed]

I'm not sure how you are getting any of that information from the static compression ratio.

You don't get it from the SCR you have it if you have the information required to calculate the SCR. With that information combined with the SCR you can accomplish a lot and have a baseline reference for most everything else.

Everything is secondary to the mass in the cylinder when the intake valve closes.

This is true but if you are going to reference anything based off volume you need to know pressure and temp to calculate mass.

VE is actually calculated as the mass of air delivered through the intake valve with respect to a mass of air equivalent to the swept volume (not total volume) at ideal density (SAE J604). While called volumetric efficiency, it is not a ratio of any volume, but of mass.

I should have used swept volume instead of total volume but VE is 100 a ratio of volume. That ratio of volume can be used to calculate mass airflow but that would require another step.

If a car has 100% VE at sea level it will have 100% VE where I live at 6000 feet. The mas airflow will be much different though.

VE is a ratio of the volume of atmospheric air that the motor takes in per revolution compared to it's displacement.
A 100 CC motor at 100% VE will take in 100 CC of air measured at atmospheric pressure. Doesn't matter where the intake valve closes.
A 100 CC motor at 50% VE will take in 50 CC of air measured at atmospheric pressure. Doesn't matter where the intake valve closes.
If you know the pressure and temp you can convert that into a measurement of mas airflow.
If you know the mass you could also calculate the pressure and temp of the air at IVC but that information is useless to almost everything.

How is trapped volume useful here? It tells you nothing useful. The trapped volume tells you nothing about what final compression pressure will be and that is all that is important. This has nothing to do with compression ratio unless you know the mass of air in the cyl when the intake valve closes. You do not need to know when this is if you know VE.
If you do not know VE then you would need to know some other way how much mass was in the cyl when the valve closed. Without knowing VE how do you come to determine this?
It's the long road to nowhere.

I feel like my example was pretty clear and relatively well thought out. I'm not sure why you sound confused.

[burdickjp]

So is it best to build with seat to seat cams such as the poncams rather than the kelford 193-B cams?

I'm sorry I missed this. It's just a different way of measuring the same thing. There's no inherent difference in cams between the two methods of measuring lift and durations.

[burdickjp]

I should have used swept volume instead of total volume but VE is 100 a ratio of volume.
If a car has 100% VE at sea level it will have 100% VE where I live at 6000 feet. The mas airflow will be much different though.

VE is a ratio of the volume of atmospheric air that the motor takes in per revolution compared to it's displacement.
A 100 CC motor at 100% VE will take in 100 CC of air measured at atmospheric pressure. Doesn't matter where the intake valve closes.
A 100 CC motor at 50% VE will take in 50 CC of air measured at atmospheric pressure. Doesn't matter where the intake valve closes.

None of that is true. I was quoting the definition of volumetric efficiency according to the SAE. You quoted me about it:

VE is actually calculated as the mass of air delivered through the intake valve with respect to a mass of air equivalent to the swept volume (not total volume) at ideal density (SAE J604). While called volumetric efficiency, it is not a ratio of any volume, but of mass.

How is trapped volume useful here? It tells you nothing useful. The trapped volume tells you nothing about what final compression pressure will be and that is all that is important. This has nothing to do with compression ratio unless you know the mass of air in the cyl when the intake valve closes. You do not need to know when this is if you know VE.

VE can be deceiving for a number of reasons, most of which are involved in how it is defined; not all of the air which passes through the intake valve is involved in combustion, some of it may go out the exhaust during overlap, some may revert and go back out the intake while the intake valve is open between bottom dead center and valve closing.

If you do not know VE then you would need to know some other way how much mass was in the cyl when the valve closed. Without knowing VE how do you come to determine this?

You are at least asking the right questions. There are entire books devoted to this and people getting post doctoral educations in the subject.

The important thing is that the composition of the cylinder when the intake valve closes.

I feel like my example was pretty clear and relatively well thought out. I'm not sure why you sound confused.

Your example was akin to someone asking the time and you answering "purple". The big, glaring clue to me was the assumption that half the volume means twice the pressure. Look at a pressure/volume diagram of an ideal otto cycle. Compression and expansion are not linear, they're adiabatic (and isentropic).

What I'm getting at is that you're being rather hostile about this while not displaying an understanding of the subject which would substantiate your hostility. It doesn't seem to be constructive here.

I think trapped compression ratio is useful in this specific conversation in illustrating in some respect the relationship between valve timing and compression ratio. I wasn't trying to reveal anything profound about internal combustion. I'm sorry it derailed this conversation, but feel it was still contributory to the conversation.

[yoshimitsuspeed]

None of that is true. I was quoting the definition of volumetric efficiency according to the SAE.

Do you have a link or source? I have never heard this definition of VE.
I am not trying to be hostile. I am just trying to discuss this but what you are saying goes against much of what I have researched on this topic.

[burdickjp]

SAE J604 1.23 defines the term "volumetric efficiency. I cited it earlier.

Prof. Blair in "Design and Simulation of four Stroke Engines" section 1.6.2 references the SAE's definition of volumetric efficiency. To be fair, he says he prefers calling it the "delivery ratio", and has a definition of his own for volumetric efficiency, which compares to the swept volume and ambient density.

Heywood in "Internal Combustion Engine Fundamentals" section 2.10 discusses volumetric efficiency as "the volume flow rate of air into the intake system divided by the rate at which volume is displaced by the piston". Both of the equations he cites are ratios of masses (2.27a and 2.27b), similar to Blair's equations, so I'm not sure why he chose to describe it that way.

I don't have my print copy of Taylor's "Internal Combustion Engine in Theory and Practice" in front of me, so I can't cite it, but that'd be the other place I'd look. It's likely his definition predates the SAE specification; and likely they used his definition. He's, BTW, the coolest guy EVER: http://web.mit.edu/hmtl/www/taylor.pdf

The important thing here is that the SAE is the authority for defining VE.

[yoshimitsuspeed]

It looks like I would need to spend a lot more time than I have right now to research and continue this discussion. I have too much going on to give it the time it deserves.
I don't have access to most of this literature at the moment and the only place I can find SAE info is on their website and it looks like they want a lot of money for it.

The vast majority of info out there says it's volume taken in vs the swept volume of the cyl but in a very quick search I can't find anything more credible than Wikipedia.
Eng-tips has some discussions on it with some mention to mass airflow but to me it seems as though it still uses volumetric airflow just as I said then uses the scientific standard of using a standardized pressure and temp to calculate mass if pressure and temp aren't available.

This is in the same way that if I'm throwing rough numbers around for turbo sizing I will use 14.7 PSI and 80f for my calculations because that is about the standard.
However if I am calculating for a known condition (Say PPIHC) then I will change those numbers to reflect that environment. This is because mass to volume ratios and pressure ratios all change and so calculations for a turbo at sea level are of zero use to seeing how it will do on Pikes Peak.

It seems to me VE is the same but like I said I would need to spend a lot more time researching to feel like I could pose a proper counterpoint beyond what I have already.

[burdickjp]

I think I'm honestly in the same boat; as I said, there are post docs about this stuff. It's not easy to wrap one's head around. I've had Blair's book for 6 years and there's a lot of it that still doesn't seem intuitive to me.

Back to topic; I think an 11.4:1 static compression ratio, as calculated earlier, should be obtainable without crazy piston domes and should perform well with the 193-Bs. Pair that to a decently massaged head and you'll have a lot of it sorted.

[AE Harold.]

Back to topic; I think an 11.4:1 static compression ratio, as calculated earlier, should be obtainable without crazy piston domes and should perform well with the 193-Bs. Pair that to a decently massaged head and you'll have a lot of it sorted.

Alright that sounds good. Now my question is would the 193-b kelford cams be able to run with the stock shims or will I need to purchase or fabricate a under bucket shim kit? And where would a buy a under bucket kit? I know the 193-b cams contain a 8.50mm and 9.40mm lift which is well above the stock lift of the regular 4age cams. Also since you guys stated that you don't need dome height to bump up compression, oldeskewitoy pistons would be a great for achieving a 11.4:1 compression ratio.

[yoshimitsuspeed]

Back to topic; I think an 11.4:1 static compression ratio, as calculated earlier, should be obtainable without crazy piston domes and should perform well with the 193-Bs. Pair that to a decently massaged head and you'll have a lot of it sorted.

Alright that sounds good. Now my question is would the 193-b kelford cams be able to run with the stock shims or will I need to purchase or fabricate a under bucket shim kit? And where would a buy a under bucket kit? I know the 193-b cams contain a 8.50mm and 9.40mm lift which is well above the stock lift of the regular 4age cams. Also since you guys stated that you don't need dome height to bump up compression, oldeskewitoy pistons would be a great for achieving a 11.4:1 compression ratio.

The standard 193 series are all designed to be run with stock buckets. 193HV all require shim under. You will need upgraded springs.
With the 193b I would aim much higher than 11:1.
To increase compression you can either increase dome volume or decrease combustion chamber volume.

[burdickjp]

Here's a write up on shimless buckets for the 4A 16v
http://austarletclub.com/index.php?/top ... ion-guide/

[oldeskewltoy]

Running shimless buckets in the USA can be a royal P.I.T.A.

I managed to purchase a set of 8 of the smallest set (13751-23030) - to use as a measuring guide, and then once I tried to order the individual shimless buckets, Toyota USA didn't deliver - assumption - what happened is I ordered the 16 sizes I needed, and a month later I was told Toyota wouldn't fill the order. My client ordered them direct from Japan, and it took 10 weeks total to get it all finalized

Ted's/Kamikaze cams claim (on some of their big lift cams) that their cams run perfectly fine on stock over bucket shims... something to think about.

[oldeskewltoy]

How long will it take to have your pistons shipped to me. I reach the 12.1 compression that I'm looking for with your designed pistons correct?

Sorry I missed this.... 2 to 3 weeks from payment to delivery Yes, my pistons and a bit of headwork can meet 12 - 1

[AE Harold.]

The standard 193 series are all designed to be run with stock buckets. 193HV all require shim under. You will need upgraded springs.
With the 193b I would aim much higher than 11:1.
To increase compression you can either increase dome volume or decrease combustion chamber volume.

So all that I need to change to upgrade the valve springs. Are there certain valve springs that I will need to use or will valve springs such as HKS valve be suitable with the duration and lift of the 193b cams.

[AE Harold.]

Sorry I missed this.... 2 to 3 weeks from payment to delivery Yes, my pistons and a bit of headwork can meet 12 - 1

Thats sounds great. Do you have a website that I can purchase your piston set or you have another way such as a paypal?
Also. Just to gain some knowledge. Why would a shimless kit be a P.I.T.A.?

[burdickjp]

It's difficult to order them in small numbers.

[burdickjp]

John at WC engineering has a stock of shimless buckets in stock in the US.
jwelch@wcengineering.com