engineering squish heads

[srech77]

In regards to the squish heads on a t500 ... I've seen a few people throw around the name RK Engineering, saying they can machine squish inserts for existing heads.

Does someone have a website for these guys ... there are about a thousand different companies that come up if you type RK Engineering into Google.

thanks - sr

[Blokhead]

http://www.2strokeheads.com/" onclick="window.open(this.href);return false;

[srech77]

http://www.2strokeheads.com/" onclick="window.open(this.href);return false;

Thanks, I actually found them earlier after doing some mad searching. I talked to one of their guys, and they can definitely do the work, but his only concern was whether or not the metal on the heads was weld-worthy or not ... I guess some of the older RM heads had an alloy metal in them that makes them unweldable ... so unless someone on here can tell me for sure that they are good to weld, I will have to take the heads to a machine shop and see if they can get it to weld or not before moving forward with the squish thing ...

I thought they were just aluminum, and I'm pretty sure I've seen a thread or two with pics of someone that filled the combustion chamber with weld, then machined it out, but I could be wrong, and maybe some of them do have a mix alloy in the heads ..

[old racer]

I have welded T500 heads and machined squish bands (for racing),
Were every single modification counts,
For road use i would not wast my time and money,I would just skim them,
But it's not my motor, and it's not my money.

[Vintageman]

You can get a lot more power from T500 without need to have squish head. Seethe factory performance bulletin

oldjapensebikes

I forget where you put this bulletin ala this old post -> viewtopic.php?f=5&t=9566" onclick="window.open(this.href);return false;

I may do half this much porting on my spare T500 engine as a next winter project.

[tz375]

And let us all keep in mind that the HP numbers quoted back in the day were corrected Crank HP (Gross) and with modern gas, a squish head is even more of a necessity to prevent a mini Chernobyl effect unless you run 116 octane oxygenated race gas and even then it would be a good idea.

[srech77]

[quote="tz375"]And let us all keep in mind that the HP numbers quoted back in the day were corrected Crank HP (Gross) and with modern gas, a squish head is even more of a necessity to prevent a mini Chernobyl effect unless you run 116 octane oxygenated race gas and even then it would be a good idea.[/quoteS

So tz ... are you saying for a street application, that it's not worth the effort, or that it's absolutely worth the effort? Or were you saying that for racing, you basically have to ...

[srech77]

You can get a lot more power from T500 without need to have squish head. Seethe factory performance bulletin

oldjapensebikes

I forget where you put this bulletin ala this old post -> viewtopic.php?f=5&t=9566" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

I may do half this much porting on my spare T500 engine as a next winter project.

Ya, I'm with you guys at this point ... I just dropped the heads off to get .020 taken off ... and with the copper gasket, I think that will be a great street combo without getting into the risk zone of 1mm+. Plus, with the chambers, porting and carb changes, it should make for a fun street bike nonetheless.

thanks for all your input. I'll post a few pics once it's wrapped up.

[tz375]

I was responding to the post about that race tuning article/Bulletin. If one were to tune an engine to that extent, then squish heads would be extremely desirable. When we push the limits of design on an old bike we taking what we like to think is a calculated risk. In reality, it's closer to a gamble, but let's not go there. Squish heads are a really good idea on a race motor for power and safety reasons.

For a mild street motor they offer a wider margin of safety but are arguably not required. They do ensure a more complete burn and lower emissions and probably slightly lower fuel consumption and marginally better power, but how much does that weigh in the cost-benefit balance?

Chat to RK-Tek and see what they have to say.

[Vintageman]

It depends how much power gain you want and how you plan to use it
.
For example I am thinking 1/3 to half the power gain shown in that bulletin and then only use it short duty cycles is my MO: aggressive street use. fast 0 - 60 mph stop light stuff or drop down a couple gears and do a quick 40 - 70 mph then back off. The fact I fear the pistons will shatter may keep me from doing more foolish stuff and with a stock old bike design. Also my experience air cooled engines just can sustain high duty cycle runs for they can't shed the heat and will fail regardless. (Not only a squish head, but one that had more efficient cooling design too).

srech77 what is your objective

The squish heads has come up many times for bikes like the T500 and I (part time hobby) see no ready commercial solution? I find there is more risk being the guy who works with some fabrication house to develop a first prototype head that can be used first cut.... usually some iterations is required when i lead the way based of a "chat" versus the exact design dimensions needed... maybe just too lazy I suppose
Is there is a potential commercial squish head out there that works for T500? Or is there a company that has taken a T500 head (saved the procedure) to fill and then machine out and existing T500 head into a squish (still street gas compression 7.0 : 1 for example) that wasn't done as a one up or IP for a specific racer?

I would be interested for sure. Maybe we have someone better than I lead and we all pich in $.

else I have no worries detuning that suz bulletin a bit for the use I defined above.

fun stuff

[tz375]

We should probably back up a bit. Squish heads are not new. The technology has been around for a long time. The first thing to get right is the squish angle which has to work with the pistons and those are curved, so there's the first challenge. Next thing to get right is the depth aka thickness of the squish band. Thinner creates a higher gas velocity which is expressed as MSV Mean Squish Velocity. High MSV good but too high is not. The data is out there on target MSV for different applications. And then there's the width of the squish band. Usually expressed as percentage of the bore area. Wide is typically better for MX type motors and narrow is more suited to high revving race motors. Wide band creates higher MSV.

So we sit down with a Head design program, or APP as it would now be called, and work through the variables and try a few scenarios to get the right squish band and then we have to consider the part inside the squish band. The combustion chamber. Are we looking for a traditional shape or small diameter and tall or flat roof with sharp corers to provide cool spots or straight sides semi conical. Owe can try to put the plug as low in the chamber as possible and that yields a torroidal shape.

That software is available and it's fun to work through different designs, but it's probably cheaper to buy a set of squish heads from someone that already tried them and knows that they work. Or get a company like RK-Tek to do it because they have made thousands of squish heads and conversions and replacement domes for Cool-Heads.

The theory is simple. The area just above the piston is the last to burn and in a quiescent (open) chamber that is more likely to detonate. Even if it doesn't detonate, the fuel there is really not burned until after the exhaust port opens so it does not useful work. A squish head firstly contains less unburned gas so it wastes less air/fuel and it is also less prone to detonation. In addition, the rapid squishing of that gas into the center of the chamber breaks up the fuel droplets and agitates the mixture. That high turbulence generates a faster flame front which makes more power and uses more of the fuel.

How much more? That's one thing that no one seems to have an answer to. It's not a lot but it helps and the motor lasts longer. To find out, buy the heads off the guy that posted that he had a pair for sale and do a back to back comparison. Or get RK Tek to weld up your heads or machine in a thick insert

[srech77]

All very good info, thanks all for chiming in. From reading about squish heads, it seems like there is the potential to extend the life of the heads, and perhaps the motor by using squish heads - I guess that's the part that intrigues me. Sort of like taking the original suzuki design and making it better ... and any performance gain is simply a bonus. After researching about the science behind squish bands, I understand they are definitely complex, and must be done correctly, and the lack of resources available out there - both for science and practice - makes me a little reticent to jump on it.

I think RK can probably do something for me, although I know they deal primarily in snowmobiles/MX, so I don't know their experience with vintage bike motors. And I e-mailed argo about the squish heads he said he has ... and maybe he can speak to what type of setup he was using them on, and whether or not it was successful/worthwhile.

If nothing else, the squish heads pique my interest ... and if we could get someone to do something on a more commercial scale, I'd be happy to pitch in. I guess part of the beauty (and problem) with restoring these old bikes, and modifying them, is once you go an inch, you might as well go a mile with them. But maybe that's just me. I'm kind of the "well since I've gone this far, I might as well do that now ..." kind of guy. And knowing there's so much potential in a t500 motor makes it hard to leave alone ...

[jeff kushner]

A
I think RK can probably do something for me, although I know they deal primarily in snowmobiles/MX, so I don't know their experience with vintage bike motors. ...

This would be wrong....RK is the company that built the inserts for the GT750 and will be building mine when I'm ready to get them done after present projects are completed. There is a picture around here somewhere showing the inserted GT750 heads and the work looks to be spot-on! It's up to you but you just might want to rethink that thought about them not knowing vintage bikes. I called Kelsey after tracing back to find who built the head in the picture. He was quite familiar with the GT engines. We talked about him building them now but he noted that it would be next to impossible for me to tell him what volume I needed at this stage. I will need to get the block decked to compensate for my lift kit before I can measure and calculate the required volume for the head. He came across as someone who had more than a clue as to what he was doing. The proof will be in the pudding so to speak but that won't come until I actually begin the build but I would not be sending him the work if I didn't have at least some faith that he would do a good job...but in all honesty, it's happened before when I thought someone knew what they were doing but got back junky, miss-matched heads and was forced to hire someone else to fix their work on one of my H2 engines...hopefully it won't happen with Kelsey.

jeff

[ja-moo]

Squish heads are science, but not rocket science. There are only a few parameters (as listed before) to look out for. Squish angle, squish width, squish clearance, correct CC's for the porting, and chamber diameter.

With today's "gas" and a static psi around 140 and above, detonation is a big problem. So depending on what your final compression turns out to be, it would be a good mod.

As long as the tuners have the parameters to work with, the work is not that hard. The main thing is to give them accurate measurements/volumes. As they say junk in, junk out.

[srech77]

Squish heads are science, but not rocket science. There are only a few parameters (as listed before) to look out for. Squish angle, squish width, squish clearance, correct CC's for the porting, and chamber diameter.

With today's "gas" and a static psi around 140 and above, detonation is a big problem. So depending on what your final compression turns out to be, it would be a good mod.

As long as the tuners have the parameters to work with, the work is not that hard. The main thing is to give them accurate measurements/volumes. As they say junk in, junk out.

Very true ... RK e-mailed me back today, and I'm thinking I might send them the heads. He said he would need the heads, a piston to measure the crown dimensions, and the piston deck height to properly measure the squish clearance.

So let's say I have them do the work for me ... are there any issues in regards to porting, chambers, etc. that I would need to think about that could get screwed up? As I said before, I'm waiting on the ported cylinders from Eric at Sundial, and I have the Jemco pipes on there now, so other than a carb rejet, that's what I will plan on starting with...

Any thoughts?