72 replies to this topic

[Rob Burgoon]

 

Simple rule at no cost to anyone would be limit camber.

 

 

[MPR22]

I for one think the eccentric bushings are a bad idea.
These will cause excessive wear to tires, bearings and more.
These cars don't need 3' or more camber.
Simple rule at no cost to anyone would be limit camber.
We all know what is max based on the cars adjustment limitations so pick a number and be done with it.
This is rules creep!

Your naïveté is quite charming.
Read past threads about the compliance issues and the cost in tires. 99s don't get 3 degs of camber and I promise you, set ups with more than 3 are on more top ten cars than not.

[Mike Babcock]

You really don't want these things on the LCA.  Here's why...

 

Two independent adjustment points on the lower control arm (caster/camber).  Imagine if the camber bolt was adjusted fully outward, and the caster bolt fully inwards.  Now, imagine yourself trying to peek through the bolt holes from front to back... you can't, because the natural plane is now skewed.  There would be a certain level of opposing bind present on each mounting point, and a much greater likelyhood of rotational shift with an offset bushing.  In reality, they'd be trying to shift even when the car was parked.

 

With the OEM bushing, the entire range of motion on the LCA, once torqued, is fully depend on the compliance of the bushing material.  This includes the the normal suspension travel, as well as the slight movement that results in adjusting the cam bolts.  So an LCA offset bushing, even if the bushing material were made of soft rubber, you'd have less compliance due to the bolt being closer to the outer housing.

 

Now consider the upper control arm... no adjustments, and a single bolt holding it to the subframe.  Effectively, a single mounting point.  Any forces that are working to shift an offset bushing are going to have to shift both bushings in the same direction.  Much less likely.  It would also have minimal impact on caster adjustment range... which is NOT something we're trying to fix, so let's not booger it up in the process.

 

Whiteline doesn't make an offset bushing for the LCA, and ICS (while they may fit) doesn't recommend using them in the LCA, for the reasons mentioned above.  SuperPro makes them... but that design uses an offset inner-sleeve.  Looks like maybe half a degree's worth.

 

We used the Whiteline's on an NA LeMons/Chump car.  I liked their design a bit better than ICS, as the press-in metal sleeve helps prevent rotational shift, and they don't need to be greased.  That car has over 100 hours on-track... no issues.  1.2 degrees additional negative camber.

 

And as Bench stated... this was requested as a "may do", not a "must do".

[Jim Drago]

 

 

 

We used the Whiteline's on an NA LeMons/Chump car.  I liked their design a bit better than ICS, as the press-in metal sleeve helps prevent rotational shift, and they don't need to be greased.  That car has over 100 hours on-track... no issues.  1.2 degrees additional negative camber.

 

And as Bench stated... this was requested as a "may do", not a "must do".

 

 

Whiteline no longer making the sleeved bushings. I spoke to them a few weeks ago, they have a two piece replacement coming out

[Jim Creighton]

JIm, don't have the dyno sheet but I did see that lap times for a 1.6 that I whistled this year that was 9.8.CR. It was still a second off the front pack, but well in front of the rest of the 1.6's.  Car had a good wheel man. I had also run into the same thing a few years ago at the ARRC and same figures and times. Figured it was an easy, not very costly change and if it makes it too fast, a weight adjustment is as easy as lead. Heck, with the change, the exact amount to cut off a stock 1.6 head could be provided.

 

Maybe someone out there has this info and can provide to Jim. Sure like to see more of these cars in the mix.

[Steve Scheifler]

I just noticed that Mazda has +0.5mm (0.020) Pistons for the 1.6. I thought they had only 0.25/0.010 a few years back. Probably just a bad memory. Anyway, that slightly increases the possibility of allowing more compression without too much off the head & block. Just thinking about the options.

[B(Kuch)Kucera45]

I just noticed that Mazda has +0.5mm (0.020) Pistons for the 1.6. I thought they had only 0.25/0.010 a few years back. Probably just a bad memory. Anyway, that slightly increases the possibility of allowing more compression without too much off the head & block. Just thinking about the options.

You can use the larger pistons but you have to run more weight.

[Steve Scheifler]

I think only the 0.25s so far @ +15, all years, right? But what I'm saying is that IF one approach for helping the 1.6 is adding compression, I'm concerned about limits to head and block cutting before clearance and/or can timing are an issue. Moving up to the OS 0.5mm gives a compression bump along with the small displacement increase. But, then all the old blocks are on their last life again, so not a great idea. What we need is a boat load of new, straight, $200 bare blocks

[Bench Racer]

I think only the 0.25s so far @ +15, all years, right? But what I'm saying is that IF one approach for helping the 1.6 is adding compression, I'm concerned about limits to head and block cutting before clearance and/or can timing are an issue. Moving up to the OS 0.5mm gives a compression bump along with the small displacement increase. But, then all the old blocks are on their last life again, so not a great idea. What we need is a boat load of new, straight, $200 bare blocks

Steve, with all your resources don't you have a source for a 1.6, 10:1 compression ratio dyno graph. Around the 19th of this month I may have access to one to compare to the 99 plus torque. Yes it may well help the 1.6 above 5,500 rpm, but to me the real issue is below 5,500 rpm.

[Danny Steyn]

I know my ignorance on the 1.6 engine is embarrassing, but Bench, if you are saying that 10:1 compression works on the 1.6 without piston-valve interference, isn't this the easiest way to get the 1.6 into the mix. Like Creighton, I want to see more of these cars in the hunt.

[Johnny D]

Remember guys, the CRB is meeting with the BoD. (end of the week)

The recommendation from the CRB has not been approved yet.

 

NASA/MAZDA/SCCA and "industry experts" have been reviewing the heads from the runoffs.

We haven't heard what the "industry experts" have found, or what data they have or what suggestions they will make or if any of it will get approved either.

 

Carry on,

J~

[Steve Scheifler]

I know my ignorance on the 1.6 engine is embarrassing, but Bench, if you are saying that 10:1 compression works on the 1.6 without piston-valve interference, isn't this the easiest way to get the 1.6 into the mix. Like Creighton, I want to see more of these cars in the hunt.

Danny, there are two interference issues really, at least that I've seen. If you cut more off the head (and allow overall height below factory minimum spec) then valves get close to pistons. If you cut more off the deck of the block, then the piston gets too close to the head.

Unfortunately you can't just measure one of each and publish what is "safe". The block castings also have core shift resulting in the deck not being parallel to the crank, which means that piston 2 may stick out more than piston 1, and so on, or a single piston may stick up more on the left than on the right. You can fix or reduce the end-for-end issues at the main journals but not so easy for side-to-side. That's why for many years Sunbelt decked all new crate blocks a fixed amount then installed different pistons with a lower compression height. And since they also cut custom cams there wasn't any timing issue.

And of course besides interference, cutting either impacts cam timing which may help or defeat the intended goal. I don't think we're talking enough to worry about the extra slack that has to be taken up by the tensioner but one more thing to consider.

So a cheap & safe way to get to 10:1 might be a great place to start, but it would require a good bit of R&D. (Keep in mind that rods stretch at high revs so simple measurements aren't enough.)
What we really need is a slightly stroked crank combined with a shorter rod and +0.40 pistons to increase both displacement and compression. Get that dude to 1700 @ 10:1 and you can start backing off the 1.8 restrictors and weight rather than slowing them more.

[Brian129]

I am very pleased with this movement on both proposals,  I am already getting prepped for race school in Feb.

 

when is the meeting that this gets approved?

 

working on pulling my stock motor, and cleaning up a set of upper arms to put the bushings in.