I am just about to start building my motor and I'm shooting for 700-800 hp and I'm using Acl race bearings and I'm wondering what you guys are running for clearances.? I have been lurking around and seen a few ideas but would like it from someone running this much power. Thanks for your time.

 

I use the Standard size ACL Race "X" bearings (more oil clearance)

OEM GSR Crank
Manley TT I-Beam rods

Mains are .002
Rods are .0018

I also run Brad Penn 20w50 and the car makes just over 730whp/530wtq

 

Depends on oil viscocity you want to run. I would go 18-20 on the rods and 20-22 on the mains with a high zinc motor oil. Depending on your location and climate would be determining factor of running a straight weight of a multi weight oil. Being in south Texas I run straight 40 weight valvoline VR-1 racing oil. Will be switching to the synthetic version of the VR-1 with my new motor.

 

 

This. This is exactly what I do, and ill tune to the 750whp range.

 

I am in the process of putting a new motor together and my clearances came out
Rods .0018"
Mains .002"

This was with HX ACL race rod bearings and Clevite HX mains. ACL Race HX main bearings are on backorder right now so I went with Clevites since they were available.

I am planning on running a 20-50 oil with these clearances same power goals as you.

 

At least 2 1/2 on the mains and at least 2 on the rods..... if you don't get at least that use an X bearing which is 1th more clearence

 

Thanks for the replies guys I'm located in mass and its summer right now. I will be running brad penn oil just deciding between 20w50 or 5w30. I really appreciate the advice. If you guys have suggestions on oil I'm all for your suggestions,,

 

Talked with a couple experienced engine builders. Told them what I came up with on paper for rods and bearings using factory bearings. Rods were all between .0018' - .0020" using factory reds and pinks and mains were all .0020" using pinks, yellows, greens, and browns.

I was told this was fine and my car should be making in the 500whp range on pump gas and then whatever the fuel system and engine can hold on race gas. Was also told that 10w-40 would be fine for the oil since this was just on the loose end of factory specs.

 

don't forget if you increase the oil weight you need to increase pressure....imagine a long pipe with holes along it and pumping water through it....all the holes should have a good amount coming out since the liquid is thin enough to pressurize through the whole pipe....once you put a thicker liquid into the pipe you start dealing with surface tension of the liquid coming into play a lot more and no longer will you have equal pressure through the pipe and less liquid coming out of each hole as you get further away from the source of the pressure. (or if you open up only certain holes along the pipe it changes everything after along the pipe)

also increasing the oil weight doesnt do exactly what you think it does...

most oils will be about the same weight at normal engine temps regardless of the weight of an oil you run. If you run the engine hot then a heavier oil weight may be needed but if you keep the oil inside of normal operating temps then heavier oil will do nothing. The weight of the oil should be determined by the operating temps of the oil.

i may not be explaining this all correctly as its rather confusing... http://www.carbibles.com/viscosity.html

 

All good info in here. I will add that if you're stuck between either being a bit tight, or a bit loose... ALWAYS go toward the looser combo (within reason).

A motor is much less likely to frag from being too loose as opposed to being too tight.

Lou

 

*Rule of thumb*

If its loose, you will know it.

If its tight, everyone will know it.

 

LOOSEY GOOSEY!!

 

Appreciate all the info. Thanks everyone..

 

Loose is fast, but don't expect to put 90,000 miles on the thing street driving it either.

Pick your poison.