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Lq4 compression for towing

General engine tech -- Drag Racing to Circle Track

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White Stripe
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Re: Lq4 compression for towing

Post by White Stripe »

Thank you mt-engines. I do have some tootsies
White Stripe
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Re: Lq4 compression for towing

Post by White Stripe »

Getting closer on getting the Lq4 together. Filing the Rings supplied with the wiseco pistons has taken me a while. I've read some info on break in oils. Is a break in oil necessary since the Lq4 has a roller cam? Another question as far as ring seating, should I drive it to break in the Rings before going to the dyno? The tune I have on my ecm is for a L59(flex fuel 5.3), so it would be running on that tune. I will have 42lb injectors in the Lq4. The L59 had 35ish lb stock injectors. My thought is the bigger injectors with the 5.3 tune on the Lq4 will keep it from running lean for long enough to break in the Rings before going to the dyno. But wanted to get opinions from others on this first.
rustbucket79
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Re: Lq4 compression for towing

Post by rustbucket79 »

Gibbs BR30 oil.

The dyno is great for seating in the rings, and the tune can be monitored so you don’t overfuel and wash down the bores.
White Stripe
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Re: Lq4 compression for towing

Post by White Stripe »

I was looking at that break in oil earlier. Thanks for verification that its good to use. For my top ring gap with my 4.030 bore I chose .018 on the top ring and .20 on the 2nd. Does this seem right for a truck that will be towing up mountain passes from time to time in Colorado? I noticed in the chevy book stock ring gap for the top ring gap is supposed to be between .012 and .020 for the lq4 and lq9 as a reference. I would think I would be fine since lots of people seem to add some boost with that kind of gap, although stock pistons and rings are a bit different than what I got.

This is the ring gap chart that came with my wiseco pistons.
http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

This is the rings I got:
https://www.summitracing.com/parts/wis-4035hf
rustbucket79
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Re: Lq4 compression for towing

Post by rustbucket79 »

With a proper tune you should be fine, plus the gap will increase during the break in process anyways. Good luck!
White Stripe
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Re: Lq4 compression for towing

Post by White Stripe »

I ordered up a set of comp cams trunnions. I noticed years past a lot of people complaining about them. Some say they have been redesigned since. Should I return them? Are they total junk?
rustbucket79
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Re: Lq4 compression for towing

Post by rustbucket79 »

We’ve used a few sets, I can’t recall any issues.
racin69z
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Re: Lq4 compression for towing

Post by racin69z »

I did a similar build on my 2002 2500hd 2 years ago and im very happy with it. I tuned it with HP tuners myself and I feel like I have a lot of area to improve at full throttle from a dead stop, but it runs much better than stock. I went with stock LQ4 pistons and 5.3 heads with the 6.0 valves. measures right at 10:1. 216 216 @ .050 .500 .500 cam 113 lobe sep. I read the whole thread and maybe I missed it, but I went with the NNBS intake and it seems to work well.

Pulling around 7500# coming out of Denver heading west on I-70 I had to drop over into the shame lane could only hold 35-40 mph on the steep pass. Pretty much the top of 2nd gear the whole way up. I am sure a better tune would help, but it got me there and back.
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