Wow! thanks for all the responses. I've figured out a few things so far:
1. I missed the fire ring when assembling the wastegate
i've since fixed this. It has definitely helped with spooling the turbo. I start building boost around 3500rpm now and I can hit 5psi between 3800 and 4200 on the street now.
2. I figured out a manual boost control setup and i'm running ~12psi now. This will do nothing for my launch, but it should help on the top end.
3. I switched to a real cam that is known to work well with turbo applications.
Sloppy Stage 2. This gave me even more midrange, but I think i my converter may still be too small for the best dragstrip performance. There is still a turbo-less spot for the first 500rpm out of the hole.
4. I've learned a lot about turbos and found out that most single turbo LS guys are using a turbo based on a T4 exhaust housing. My turbo is only 69mm, but it uses the larger T6 housing and fairly heavy internals. This has a lot to do with how slow mine spools up. For around $400 and some exhaust work, I can upgrade to
this which should help my spool a lot.
5. I've talked with some guys running T6 turbos and I'm going to add some timing in the <5psi zone to try to get it to spool faster.
Quote:
Originally Posted by Super73
Bigger converter and a stickier tire. Perhaps a 2 step to help build boost.
That's where I would start.
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Quote:
Originally Posted by Dynospeed
Which ecu are you running? How are you building boost on the line and holding a certain boost level? Do you have a trans brake? That little turbo should come on lightning quick but there is a lot better turbo options depending on your end goal.
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I currently have no boost until i'm out of my 60ft. That's why it sucks so bad
No transbrake. I built the Th400 myself so I could probably figure out how to add one.
The ECM is a Megasqirt MS2 which will do 2-step, but not while controlling a v8. I'd have to step up to a MS3 which is another grand.
Quote:
Originally Posted by rpmerf
This 100% is what you need to be concerned with. The turbo should be spooled when you leave the line. It sounds like you are leaving the line, experiencing turbo lag, then the boost hits.
Wondering, depending how you stage if the turbo just doesn't have enough time to spool before launching. I've seen people sit at the line riding the converter for 10+ seconds to build boost for the launch. If your there on a test and tune night, you might want to give it an extra second or 2 to see if you can get that turbo spooled.
Some things that help with lag:
Make sure your waste gate it 100% closed when spooling.
Exhaust is a huge deal. You may benefit from some cutouts as early as possible so the exhaust doesn't have to go through the mufflers.
You can retard the timing while staging to help build boost.
Heat helps your turbo spool. Wrap or coat the exhaust manifolds.
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currently i haven't seen any boost below 3500. My converter won't budge past 3000. On the street I'll start spinning the rear if I try to hold it with the brakes.
Wrapping the crossover pipe is in the plans for this week. my dipstick tube was leaking and i wanted to fix that first. I don't want oil on my wrap. The manifolds are very thick (cast iron and schedule 40). They should retain heat well.
Out of the turbo I'm 3.5" exhaust dumping just after the cab. The only muffler I have is a 8" glasspack that's 3.5" all the way through.