I wanted to get some inputs from engine builders on what steps you guys take to ensure engine reliability and power.

How do you choose MAX operating rpm?

Choice of material for rods? Aluminum/steel??

How you choose what Bearing, PTW, ring clearances to run?

Is R/S ratio a big factor when building a road race engine?

How do you feel about cutting a portion of valve guide to increase CFM in cylinder head?

opinions on whether to get head ported or not??

Any secrets for improving reliability??

Others feel free to ask questions as well.

 

I wanted to get some inputs from engine builders on what steps you guys take to ensure engine reliability and power.

How do you choose MAX operating rpm?

-This is up to the valve train. The valve springs/and lift of the cam are things you look into here. Piston speed is another factor.

Choice of material for rods? Aluminum/steel??

-Aluminum is light and can help make hp and get rid of rotational mass. They are $$$. Steel is great with upgraded hardware.

How you choose what Bearing, PTW, ring clearances to run?

-ACL and King are great. You need to look into the metal content. Coatings will help with less friction. Stick to the factory clearances on the bottom end unless you are going through it often. Oil weight plays a factor on bearing clearances. Ring gap will help with compression. If you change from cast to forged this will change. The metal grows.

Is R/S ratio a big factor when building a road race engine?

-idk enough to comment on this. Your r/s plays a role in torque and how the motor revs. If you are looking into changing this contact a machinist/parts maker (Eagle, BC, JE, etc) about options.

How do you feel about cutting a portion of valve guide to increase CFM in cylinder head?

-Look into rules of your class and see this applies. Sometimes a trip to RLZ and the 5 axis will help with this question.

opinions on whether to get head ported or not??

-Free HP. Look into rules of class to see how much you can/cannot take away.

Any secrets for improving reliability?? Use accurate measuring tools and do math.

-Make sure the engine is tuned by someone who knows what they are doing (RLZ, Bisi, Churchs, etc.)

These are my options and I know I don't know everything so I ask a professional or friends in this market. I know I can learn something new everytime I talk to my machinist.

Good Luck

 

I'm not an engine builder by trade, but I'll offer a little input based on my experience.

First and foremost, what specific engine are we building and for what purpose? What's your budget? Do you want as much power as possible at the cost of longevity?

1. Typically it's a few hundred rpm beyond where the engine makes peak power. If you know what cam you're going to run and you build the engine around it you'll know about where it makes peak power before you even get it on a dyno and you'll know where you need to beef up parts to keep up with the heightened power band that results from most aftermarket cams.

2. I've never used alum. rods before.

3. Based on intended power output and application. Typically a naturally aspirated 1.8 dedicated road race engine will be happy near and sometimes beyond factory service limits for bearing clearances. P2W depends on the pistons being used; same goes for the rings.

4. I don't have a problem with notching valve guides to increase air flow, but I would strongly recommend not shaving them off completely. The valve stems and guides wear much more quickly from what I've seen. So yes you'll get 20-30 more cfm on a flow bench if you shave the guides off but at the cost of longevity.

5. Is there room in your budget for head porting?

6. As far as reliability goes, proper procedure and cleanliness during engine assembly goes a long way. Also keep in mind the non-literal meaning of RPM.

Missed this initially. R/S ratio is a factor, but plays more to the safe rpm limit for reliability's sake more than anything.

 

This is just topic/question that 's been on my mind. Just wanting to learn more..
So these questions dont apply for rules/restriction ect..