High boost 5.3 Headed to the Dyno, What Will it Make?
Thread Starter
Teching In
Joined: May 2019
Posts: 34
Likes: 5
I talked to some tuning friends of mine and they thought the dyno chart looked like valve float. I’m going to re-measure for pushrods. I wonder if my pushrods are too long and hanging the valves open under power.
That would makes sense as to why the power falls off so early. I’m not sure if that explains why it makes torque so far out though.
That would makes sense as to why the power falls off so early. I’m not sure if that explains why it makes torque so far out though.
Thread Starter
Teching In
Joined: May 2019
Posts: 34
Likes: 5
I was able to get in the garage for an hour tonight and I measured the pushrods. They are the proper length. With a pushrod length checker, I get around .035" of lifter preload. I checked both valves on a couple cylinders.
The hotside is air tight. I just fabbed up the hotside and checked it on install, but you might be on the right track. Next on my list of things to check is to see if my flex pipes have blown out in the inside. Maybe the exhaust is so restricted the engine just can't breathe. I also checked to make sure the cam is installed dot to dot, it is. I did not degree the cam when I installed it though, just dot to dot.
I'm going to be in the garage working on it tomorrow evening. Look forward to more updates.
I'm going to be in the garage working on it tomorrow evening. Look forward to more updates.
Thread Starter
Teching In
Joined: May 2019
Posts: 34
Likes: 5
I’d say we found what the engine was fighting. The hotside is 2.25” pipe so with the flexpipes blown out like this, this makes them what, 1.5” pipe? I’m going to get these cut out and fix it with something better. Hopefully that’s the entire issue.
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Last edited by SLOW SEDAN; Aug 20, 2020 at 08:17 AM.
Thread Starter
Teching In
Joined: May 2019
Posts: 34
Likes: 5
I’ve never had issues with the braided flexpipes on my other hot sides I’ve made. However, those were pump gas T4 turbo setups that don’t make a bunch of power. Lesson learned.
I’m going to a no prep race at an airstrip this weekend so hopefully I can borrow someone’s draggy and get some data.
I just fixed the hotside last night and the car would barely idle in open loop because the fueling changed so much. I can’t wait to drive it.
I’m going to a no prep race at an airstrip this weekend so hopefully I can borrow someone’s draggy and get some data.
I just fixed the hotside last night and the car would barely idle in open loop because the fueling changed so much. I can’t wait to drive it.
Thread Starter
Teching In
Joined: May 2019
Posts: 34
Likes: 5
Just to follow up. I went to the track last weekend and all I can say is wow. It definitely woke the car up. When the exhaust was plugged, I could run 28lbs of boost without running out of fuel pump. Now, it’s out of fuel pump at 21-22 lbs of boost. So it’s safe to say it’s making a lot more power on a lot lower boost levels. I don’t think I’m going to take it back to the dyno anytime soon, but I’m really happy I figured out the issue! Thanks guys!