My Precision 6870 turbo...

[harris48cars]

my 6870 doesn't seem to be spooling like it should or maybe the ball bearing turbos aren't all I've heard they were. My combo is a 249 stroker with race ported GN1 heads, 220/220 roller cam and a 9/11 3200 stall converter. Turbo has an .85 exhaust housing. It takes all of 1st gear and most all of 2nd to get to the 20psi I have it set at. Make no mistake, when the car hits 3rd everything becomes a blur. My previous set up was a 231 with ported irons 214/214 roller and a TE45. Ran the same converter. That set up spooled almost instantly. I've checked everything and I do mean everything. All exhaust components are tight and working properly. Could the .85 housing be the problem? I'm not willing to loosen my converter anymore. It's exactly where I like it. XFI fast on both setups and tuned by the same person.
I did read a post were someone using this turbo with a 2800 stall convertor said it spooled just like stock. Seems hard to believe. Opinions before I call Precision?
Gary torque

 

[Phoneguy]

What wastegate are you using ?
CO2 ?

Bryan

 

[Nick Micale]

............ a 9/11 3200 stall converter. Turbo has an .85 exhaust housing. It takes all of 1st gear and most all of 2nd to get to the 20psi I have it set at. Make no mistake, when the car hits 3rd everything becomes a blur. My previous set up was a 231 with ported irons 214/214 roller and a TE45. Ran the same converter. That set up spooled almost instantly. I've checked everything and I do mean everything. All exhaust components are tight and working properly. Could the .85 housing be the problem? I'm not willing to loosen my converter anymore. It's exactly where I like it. ........
Gary torque

You may like your converter where it is, but your Precision turbo does not like it, especially with the .85 housing.

No matter if the turbo is a ball bearing or not, the converter MUST be matched with the turbo if you want fast spooling and response.

I run a 3600-3800 NLU stall on one of my street cars with a TE-45A, and it will throw you in the back seat on a hard street launch.

Unfortunately you fell for someone's comment that 67/70 BB turbo responds good with a 2800 stall converter and a Precision exhaust housing, but I would call that statement pure B.S. We installed a 62mm BB turbo with stock converter, and it responded much worse than with the stock turbo.

I just pulled a tranny this AM from a car with a 67 turbo that had no response at all leaving with the modified 12" LU 2800-3000 stall. This was from a reputable tranny shop that should have known better to think it would perform properly?

When I build a turbo car or just do performance mods, which I have done over 1000 times, I select the converter, not the customer, as they ALWAYS would have in mind a converter that is too tight for their new application.

 

[Mr.Spool]

My combo is a 249 stroker with race ported GN1 heads, 220/220 roller cam and a 9/11 3200 stall converter. Turbo has an .85 exhaust housing.

very similar combo on one of the cars up here but the car has 71 billet bb.car spools very good and clears 700rwhp ptc 18 blade gets it done.i believe the 68/70 is the replacement turbo but can support more power.

 

[Mr.Spool]

It takes all of 1st gear and most all of 2nd to get to the 20psi I have it set at.

I see this all the time.sometimes bigger is not better.its going to take more ex gas volume to fill that .85 ex housing and big turbine wheel.you will need to either loosen your converter, switch converters, but you will need to raise the flash stall.other option is to run a small nitrous shot 35/50 shot will do the trick.i am assuming everything on the car is in working order.

 

[Mr.Spool]

I did read a post were someone using this turbo with a 2800 stall convertor said it spooled just like stock. Seems hard to believe

spooling can be confusing to a lot of guys.2800 on a 68/70 109 is going to have no real turbo response.

 

[Ttype6]

Could the .85 housing be the problem?

Yes. Do you still have the 45a?

 

[Mike Licht]

What is the lobe separation on the cam and where is it installed? You need a modern converter

 

[BEATAV8]

What will it do when you stall it with the car stationary?

 

[20psiofevil]

It sounds like you have an issue somewhere. That turbo should be lit and full boost by mid 4500rpm in first gear. I would double check the wastegate or check for a boost leak somewhere.

 

[bison]

A 2800rpm converter will spool a low 9 sec turbo like stock? I have a bridge for sale real cheap. It's in Brooklyn NY. Sending PayPal info in a PM. I wouldn't expect it to spool properly till engine rpm is over 4400. From there it should be all in in less than half a second. You might be able to squeak 4200 if the CR is high enough and the air is good. That turbo won't work anywhere near its potential at 20psi on an engine that small. You have a 12 sec converter with a low 9 sec turbo


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[jasjamz]

Something is not sealed properly. Want a cheap, quick test? Buy the RJC Stainless Downpipe block off plate.
That will seal the waste gate hole on the turbo housing completely. It will show you how the car will spool BUT WILL MAKE AS MUCH BOOST AS POSSIBLE WITH OUT BEING ABLE TO BLEED OFF AT 20, 30, or 40 psi.
Test it on the foot brake, trans brake or a area and release the throttle when you see 15-20 psi.

 

[TurboTnZ06]

The wastegate setup has a lot to do with spooling. The stock style actuators start opening early. If you have one of those, wire it shut so it can't open, if in fact it is sealing at all when closed. For an external gate, I run a 15# spring to keep it closed during spoolup and around town. Boost response is near instant, 0-20 psi boost in under half a second. Then it only bleeds off boost when under boost with a simple ATR bleeder on one side of the diaphram and the other side is open to the atmosphere (where the spring is working to keep it closed).

 

[harris48cars]

Pretty sure the problem is the .85 housing. I sold the TE45. I should have kept it. Anyway everything has been checked out. All is tight and working correctly. Once this car it's 20 psi the acceleration is unreal. Ive owned a half dozen stage engines a few 274s. This is the baddest of all. Of course the technology has changed dramatically since back when.
Gary

 

[rag231]

Your 249 is badder than any of your 274 stage motors?

 

[GNBRETT]

check ur waste gate and make sure there isn't a tear in the baffle. it happened to me just recently with my turbo bike and there was a tear in the baffle.

I'm not sure why u think at 20 psi its gonna do much. thats a pretty big turbo. replaced the 71 I believe. get a PTC converter. like Bison stated at 20 psi its still sleeping....

 

[king kong]

check ur waste gate and make sure there isn't a tear in the baffle. it happened to me just recently with my turbo bike and there was a tear in the baffle.

I'm not sure why u think at 20 psi its gonna do much. thats a pretty big turbo. replaced the 71 I believe. get a PTC converter. like Bison stated at 20 psi its still sleeping....

 

[TT/Ameasap]

Nothing wrong with running low boost. Bet it's a 9sec car with traction and a ptc

 

[johnplogii]

If it won't make 20 psi till 3rd gear, you have an issue besides too tight of a converter. Likely an exhaust leak somewhere between the heads and the turbo, or a problem with the wastegate setup.

 

[jasjamz]

Pretty sure the problem is the .85 housing. I sold the TE45. I should have kept it. Anyway everything has been checked out. All is tight and working correctly. Once this car it's 20 psi the acceleration is unreal. Ive owned a half dozen stage engines a few 274s. This is the baddest of all. Of course the technology has changed dramatically since back when.
Gary

Can you post a video of it spooling?