I think I finally figured out why I cant build more than 5-6 lbs with the 10 lbs spring in my waste gate. My converter doesn't seem to be holding on past about 6 1/2 lbs. My son videoed a run for me from the pass seat a while back and I slowed it to frame by frame so I could see the relationship between my tach, boost, and speedo. I launched on 0 boost at a part throttle 2800 rpms. As soon as my foot met floor the boost controller goes straight to 6.7 psi. the tach climbs rapidly to 4500, but the speedo doesn't move higher. The boost drops to 5 psi and the speedo climbs rapidly to 45 mph, tach hits red line at 6500 and 45 mph (should be 58 mph without converter slip). I shift to second and boost jumps back into the mid 6s, tach drops back to 5500, boost drops back to high 4s low 5s till red line top of second (speedo shows about 85 mph).
Anyone ever seen their converter give out at a certain boost, like it wont hold anymore than xxx hp ? The converter was speced by my trans builder for NA and was pretty much maxed out at the 525-550 hp my engine made before boost. At the time I bought the trans and converter, my budget was tight and I couldn't afford a billet converter. My trans builder warned that the converter would be "OK" as long as I didn't pound it at the track too much ( that was before boost !).

 

Another interesting point.......I started with a 7 lbs spring initially and made the same boost levels the 10 lbs spring makes now.

 

I'm no expert but I've read that when evaluating whether you're blowing thru the converter is when at WOT and you shift, if the RPM doesn't drop significantly as your transmission engages the next gear. From what you've said above, you dropped a 1,000 rpm. Maybe your converter is just too loose?

 

Yea, that could be, I guess. I'm throwing a lot more power at it than when it was NA. It use to drop from 7k to 4800ish on the 1-2 shift before the turbo install, which is close to manual trans territory. Today I checked the hot side again, but with a rubber hose as a stethoscope and I found 3 small leaks, so I just pulled the headers to turbo piping and will fix those and see where the boost goes.
I have a converter coming anyway, but it will be 3 weeks before I see it. Oh well

 

what converter did you order?

 

Revmax stage 5 billet 3200

 

Continue with this and you may end up destroying your bottom end with that converter. You really need to put a turbo ready converter behind your motor. PTC is a good choice. And yes, I understand that turbo converters are really expensive.... but what's worse, killing your motor and in the end STILL having to buy the converter...or getting it now and hopefully saving your motor?

 

Like I said in post 6, I have my converter ordered. The Revmax should be just fine with my setup. There are several guys on here that use their converters on their turbo builds and have stellar results with them. I gave Revmax all my specs and they are building the converter to suit my build.

 

What does the RPM drop to on the shifts?

 

from 6400 to 5500 on the 1-2 shift I recorded.

 

That's not too bad to me. I'm assuming its not a close ratio gearset in in the trans so it could be a little on the loose side.

I'd call up whomever made the converter and talk to them. They may want to tighten it up a little and try it again. But keep in mind, its going to act different each time you add more power to it. If its not a street car, I'd look into a dump valve setup. (talk to the trans builder) That allows you to run a very tight converter, and still lets it come up on the brake pretty quick.

without driveshaft data to over lay and calculate slip.. makes it difficult to tell.

 

2.74-1.72-1-.067 . Its just a little street car/toy. I'm gonna go ahead and go with the billet front cover/rear anti balloon plate converter and "S"can the 9.5" factory cased converter that's in it now. It was never built to hold 700 rwhp and even if its "OK" now, its not worth taking the chance of wiping out a 2500.00 trans if it comes apart down the road. Thanks for the input , a05c.

 

Spend the money on a good converter, with a company that will stand behind their product.
We've had extremely good luck with PTC and would recommend them to anyone. (Granted race car vs street car/toy)

 

Yea , ive heard really good things about PTC. I went with revmax, just based on customer feedback . Not so well known here on LS1tech (even banned now , I think), but I'm convinced they know their stuff and they have done a good bit of work with turbo stuff too. Price for what Is offered is what made the choice for me and the fact that they are made to order in North Carolina. Cant let PTC make all the money ! LOL

 

Measure your exhaust back pressure.

A slipping converter isn't going to limit boost in my experience. Even if the converter is slipping the engine will still make boost. Possibly more boost due to the higher RPM.

Unless you are running 1:1 back pressure ratios (doubtful) the rated spring pressure will not correspond with the pressure you see at the manifold. Even then things like valve diameter and WG chamber size come into effect. If you want more boost, install a heavier spring and/or a boost controller of some sort.