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LQ4 swapped with LQ9 pistons

I have an 03 LQ4 with pressed pins. I'm wondering if LQ9 bushed Pistons would work with my rods, using them as pressed..

I had one company selling Pistons say it would, but since the piston pin is different diameters, Im not sure if it would.

Would bushed pins just slide in and work using the clips, or would the pressed pins work on the bushed Pistons..

Anyone know.

Thanks

5 answers2 replies

7 Comments

Crazed Performance Repair

Feb 05, 2022

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Looks like the press fit is based solely off the wrist pin based off that information. With that in mind I would say the pistons of the LQ9 are likely a tighter wrist pin hole. So worst case scenario, you may need to hone the LQ9 pin hole out slightly to allow it to fit. You will have to base that off how the pressed pin fits. You want a tight but free sliding pin in the piston.

jameswis01

Feb 08, 2022

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Replying to

@Crazed Performance Repair

I just thought I'd let you know. I watched one of your videos about cam bearings and how the cam catches when you remove it..

Then you talked about race bearings and how the one set was narrow compared to the other.

I'm going to attach an image of bearing info from King Bearings and they actually make "wide" and "narrow" sets.

Also some food for thought about bearing materials.

I always use Aluminum Bi-Metal bearings as that's what has been stock in A LOT (not all) new cars since the mid 90s and the "modern" Tri-Metal babbitt/Lead bearings were used starting back in the 40s. Keep this in mind. Engines back then all the way up to the 90s... 100k miles was considered "High Mileage".. 90s and newer, 100k is considered "Low mileage" now as most new motors will run 200k plus..

Some of that is due to better machining but I think some of it has to do with better bearing material. In particular the aluminum bearing.

I've put aluminum bearings in all the old small blocks I've rebuilt and some of those now have 350,000 plus miles..

A lot of companies will say the Babbitt lead bearing is better for racing because it has a more giving structure for debris. And that's true. Ideally your oil should be clean, but in a race engine the possibility of small particles breaking off of something and making their way into a bearing is much higher than a standard use motor.

The aluminum bearings have a much better wear property than the babbitt/lead.

Also underneath that Babbitt lead bearing one of the layers is copper.

Copper is a soft metal except for when it gets bent very quickly and then it anneals which in my experience that copper annealing is hard enough to damage the crank surface.

When an aluminum bearing fails it usually knocks before it ever gets to the steel backing plate leaving the crank in good condition.

And there are a lot of companies now that are making aluminum race bearings just because overall tests are starting to show the aluminum bearings are just performing all out better.

That was just some food for thought I'm going to post a picture now and if you read the small lines it will even say narrow or wide so on and so forth..

Anyway thank you for getting back to me and I really appreciate your help and your thoughts and your time.

One other thing I would like to know your opinion on..

I'm going to be building an lq4 to replace a 5-3 in my 2000 Silverado.

Definitely not using the 317 heads. Im probably going to use a set of 799 heads and I'm waiting to find out if a friend of mine has a set of flat top pistons and a set of Gen 4 rods which would solve my problem anyway.

The question I had was what cam would you choose for an lq9?

Walking to make as much power possible down low and never plan on going over say 5,000 RPM..

Looking to do some burnouts once in awhile and mainly daily driving and towing..

Was thinking about a BTR stage 2 cam.

Thoughts?

Or what cam would you use to get extra grunt?