Hemi Build #3 -Boogie Woogie Woogie

[ezcome-ezgo]

This is all I can see...

Keep up the good work though.

 

[bob58o]

I ordered the 1.2 ratio roller tip rocker arms.
http://www.nrracing.com/product-p/nrrock-hemi.htm

These Rocker Arms require shorter Pushrods, typically 5.260 or 5.340 depending on cam and head milling.

212 Predators (Hemi Head)
5.540 Stock Length, most applications
5.440 (-.100) use with extensive milling
5.260 use with NR Racing Hemi Rollers
5.160 use with NR Racing Hemi Rollers and heads milled .065 or more, also with large base circle cams.

Kentucky Boy is kind enough to send me some 5.26" Pushrods and is saving me about $25.
Thank You so Much!!!

Lets learn about putting ratio rockers in a Hemi Head.
These videos have so much good info.
https://www.youtube.com/watch?v=QuKsRRrDeXk

 

[bob58o]

Ratio Rockers will usually hit the valve cover.

Always wanted one of these...
http://www.trjkarting.com/ambush-racing-billet-hemi-valve-cover/

Or NR sells a spacer...
http://www.nrracing.com/product-p/200vcspacer-hemi.htm

Or you can grind away inside the stock valve cover as described in Jody's video.

 

[bob58o]

I suppose the smart/safe thing to do is wait for the rockers and recheck P2V clearance before sending the head off for milling and a valve job.

https://www.youtube.com/watch?v=dVSjCvGFMnM

 

[bob58o]

I replaced the the crank bearing (I did the one on the side cover earlier).

When I installed the stator coils, I used red loctite and and phillip head screws.
I regretted that choice while I was tightening the screws. I should have used a hex head.

I decided I was going to try to heat the block to remove the bearing without first removing the stator. Didn't work as planned. I heated the aluminum around the bearing to almost 300 degrees and the bearing wouldn't fall out. Guessing that the installed stator held the the aluminum tight. With the heat, I could have probably removed the screws and stator, but I'm not that smart. I hope the heat didn't damage the stator. The whole block got pretty warm.

Anyway, I pulled the oil seal and tapped the bearing out.
I installed the new bearing and attempted to install a new seal.
I knocked the seal in too far. So I pulled it out and tried again with another new seal.
Had to use both new seals I ordered even though I didn't replace the one in the side cover.

I think this is about right. Maybe the seal could go in a bit further?

 

[ezcome-ezgo]

https://www.youtube.com/watch?v=gLo-ylNPXyE

 

[bob58o]

Nothing is over, but getting close.
Once I install the ratio rockers and recheck P2V clearance, I will decide If I have room to install a 28.5mm Valve.

The math shows going from a 27mm to a 28.5mm Valve (if canted at a 12 degree angle) will only decrease P2V clearance by about 0.006".

 

[Kentucky Boy]

Pushrods are going out today after work.
Edit: Post office said you should have it Sat.

 

[bob58o]

Pushrods are going out today after work.

 

[bob58o]

1.2 Ratio Rockers with 27mm Intake Valve

VS

1.2 Ratio Rockers with 28.5mm Intake Valve

 

[bob58o]

And lastly...

Even though it is telling me my DCR is 8.5 :1, it is telling me my Theoretical Cranking Compression is 223 PSI and it is retarding the timing until about 5500 RPM due to me selecting 93 Octane (which I think I can use with 8.5 :1 DCR).

If I up the octane to 110, it doesn't retard the timing (which I cannot select manually) and this is what I get.
24 degrees at 3000 RPM.
25 degrees at 4125 RPM
26 degrees at 5250 RPM.
27 degrees at 6375 RPM

 

[bob58o]

Or since the finish line is for quitters....

2.815" Wiseco Piston and 3.595" Rod????
This is supposed to be a drop in combo.
Hemi Piston Compression Height is like 0.900"
Wiseco Piston Compression Height is 0.640"

Piston top 0.260" lower than the stock piston.

Rod would have to be the Predator Crank, with .490" wrist pin and 3.595" Long.

My current set up has a 3.328" Rod and puts me about flush.
This rod is 0.0267" longer.

The piston would be about 0.007" higher than it is currently.
I would probably use the 72mm x 0.045" gasket and have to rework compression ratio and stuff because now I'd be rolling with a Hemi Predator 220cc.

2.815" is the biggest THEY say you can go without sleeving the block.
I'm not sure the gain is worth the money. New Piston, New Rod, Boring the cylinder, new wrist pin......

 

[bob58o]

3.00" Bore is interesting.
250cc?

 

[bob58o]

I decided against the 2.815 Bore.
If I hadn't already purchased the 3.328" Rod, I probably would have a 220cc in the making.
But since I don't want to pay for another rod or cut the piston, I will stick with the 2.756" stock bore.

I am planning on the bigger intake valve if P2V clearance allows, which I think it will.

While I'm waiting on the NR 1.2 roller tip rockers,.... here is the valve lift with the stock rockers vs the 1.2's. I used 1.05 :1 Ratio for stock. I've heard anywhere form 1.0:1 to 1.1:1 for stock ratio.

I'm not sure that 0.050" lift overlap is important, but the ratio rockers add a few degrees of 0.050" overlap. from about -1 degree overlap to about 4 degrees of 0.050" overlap. Increase of about 5 degrees.

 

[bob58o]

One of the rocker arms doesn't fit.

The dimensions on the two I received are off from each other.
One is about 0.010" wider than the other. The thinner one won't fit over the mounting things in the head.

Uggghh..

The CrMo pushrods showed up at the same time!
Thanks again Kentucky Boy!

 

[bob58o]

Starting to think about TC tuning.
When to engage?
When to shift?

For offroad, Engage around pk TQ? 3300 - 4000 RPM?
Higher engagement might mean I can ward off low RPM knock (in case the internet was wrong about being able to run 93 octane with 8.5 DCR).

Begin to Up-Shift around pk HP? ~5200 RPM?

50T:8T = 6.25 : 1
7" Driven Unit is 3.13 :1 in Low and 1.12 :1 in High

6.25 :1 x 3.13 = 19.56 :1
@ 5200 RPM, w/19" Tires... 15 mph.

6.25 x 1.12 = 7.00 :1
@ 5200 RPM w/19" Tires... 42 mph.

If the upshift and downshift happened in an ideal fashion (where the RPMs remained constant at pk HP during the entire up- and/or down- shift) then I would be at pk HP from 15 to 42 mph and if the powerband extends ... 52mph at 6500 RPM.

This pic shows me attempting to tune out the flat spot with the simulator. I guess I need to keep the exhaust pipe ID 0.87".
Not sure how a multistage pipe changes stuff. I was just using an average diameter to approximate.
22" @ 0.87" ID
22" @ 0.93" ID

Gains at
4800 RPM with the smaller pipe.

Pic is also what I was using to figure out TC tuning.

 

[bob58o]

^^^^
That is how you tune a CVT on paper.
Basically I would always be at peak HP, which sounds good to me!!!
3300 RPM engagement is easy.
4000 RPM would be just as easy.

How to get the upshift to occur at around 5300 RPM???
Once I get the driver springs I want, I will play with driven preload and/or the 30 series yellow spring.

Some Baja SAE Briggs CVT tuning stuff...
https://www.cogentoa.com/article/10.1080/23311916.2017.1398299.pdf

As the intended use is in off-road racing, the aim of CVT tuning is to get the higher initial torque inorder to provide it a strong push during launch, slopes or muddy patches. So the engagement RPM is needed to be at peak of the engine torque curve. On another hand, shift start RPM is needed to be at the peak of the power curve of the engine so that the entire shift range can be placed in peak power of the engine (constant RPM) (Aaen, 2007).

This is due to higher power requirement in CVT shifting phase to help vehicle in gaining top speed more quickly while coming out of a corner. Because shifting range is the most prevalent case in real driving conditions, if higher load condition (turns or obstacles) occur in this range and higher torque from the transmission is needed. The engine rpm falls during this (if CVT is not properly tuned) and it takes time for the engine to regain its RPM. Thus reducing vehicle acceleration.

So, CVT needs to be tuned such that in shifting phase higher torque demand can be just met by downshifting CVT while keeping engine speed constant (Aaen, 2007). Keeping these points in consideration engagement and shifting rpm were decided as 2900 rpm and 3600 rpm respectively as they are the peak torque and power rpm of the engine (Figure 3).

 

[bob58o]

Comparing P2V clearance before and after the 1.2 rockers helped me determine the stock rockers were 1.1 :1 Ratio. Was just about 0.130” and now about 0.100”.
0.280 lift cam with 1.1 rockers is 0.308”
0.280 lift cam with 1.2 rockers is 0.336”

A difference of 0.028”.

More importantly, I should be fine installing a 28.5mm intake valve.

 

[bob58o]

or Maybe clearance with the stock rocker was closer to 0.140” and stock ratio was ~1.06:1?

 

[bob58o]

After hitting both sides the mounting post thing in the head AND both sides of the inner rocker arm with a file....

I have both installed.
NR offered to allow me to return it for another, but I opted for a file.