6870 precision turbo on a stage 2 any one?

[sackracing]

http://www.tciauto.com/tc/racing-calculators/

 

[ttypewhite]

It is a 4.0 bore long rod stroker motor with TA production style heads.
Q16 and 16 degrees of timing. And it is a three bolt 68.
He took it to 36 pounds of boost on the street and a cylinder sleeve let go.

I would be discouraged about only gaining 100 hp going from 18 to 31 psi. I think it's too small a turbo for a big cubic inch motor.

I make comparable power at 28 lbs with a 245 ci stock block. If you run the numbers, it should take 863 hp to run 148.9 at 3350 pounds.

I've always thought that the 76 was the optimum turbo for a stage motor.

But that's just an opinion.

I would be curious to know more. ie: what tranny and converter he is running, what ignition system (stock coil pack, distributor, or coil on plug), compression and who tuned it just to name a few. There are a lot more variables that can effect the overall outcome of the results. Half the time guys get on the dyno, they are there with problems, and trying to sort through it. If everything was perfect then I would say the turbo ran out of snort for a bigger motor then what the TSM guys are doing. But without knowing everything it's hard to say.

 

[sackracing]

It's a 9.0-1 compression motor, tr6 ignition with truck style coilpack, 230/230 roller cam.
Tuner and driver is a mod motor mustang builder/tuner/racer.

It's a 200 trans and ptc converter.

 

[sackracing]

A stock stroke TSM motor with the 68 makes way less backpressure then my stroker.

 

[nat86]

Any idea what blade ptc?

Sent from my SM-N910T using Tapatalk

 

[sackracing]

I'll find out

 

[ttypewhite]

Have they tried another turbo on this combination with everything remaining the same, if so what was the hp from the session.

 

[sackracing]

No. It was just completed last week. And the block was hurt Saturday nite. He's gonna build a new motor with a ta block and try it again.

 

[ttypewhite]

Sorry to hear!!

 

[BEATAV8]

Ouch!

 

[nat86]

That sucks poor guy

Sent from my SM-N910T using Tapatalk

 

[forcefed3.8's]

On a Mustang dyno with a 3 bolt 76hpq on my 274" stage 2, I broke 600rwhp at 18 or 19 psi, and made 767 at 25psi. It was picking up over 30hp per lbs of boost going from the low 20s to 25, but was boost limited due to running an internal gate. The 767rwhp was enough to run 8.94@151 at 3470lbs.

 

[nat86]

What hp is the 76hpq rated at? Precision has the 6870 rated for 1100 not sure if that's for the four bolt or 3 bolt

Sent from my SM-N910T using Tapatalk

 

[sackracing]

The 1100 number is with the four bolt housing

 

[forcefed3.8's]

It is rated at 945. The cast 76 compressor far outflows the 68 turbine and 3 bolt housing. It would be interesting to see how the new 70 wheel flows in the 3 bolt. I think anything over the 66 turbine is a waste.
Now to be fair, my engine was purpose built to deal with high backpressure. I would have liked to test the 6766, 6768, 7168, and 6870 all kind of back to back to see how each acted, i would even like to see an old school 70gtq.

 

[sackracing]

I've heard several people say that anything over a 66 turbine in a three bolt housing is a waste

My car was faster with a 67/68

 

[GNBRETT]

I personally don't plan on running mine past 25 lbs on pump gas and alky. the alky will be a little different then the norm. Bison is working on somethn different for me but nonetheless I'm gonna beat the balls off it like he does his blue car every summer and see long long it lasts.

I am considering the 6870 in a 4 bolt so I can have somthn to grow into. I will be running a similar setup to Bisons blue car. Bison will be building and tuning it and will likely provide the intercooler for it as well. him and Alan are working on somthn a little different.

its a Don Cruz build stock stroke with good pistons and a girdle. Champion irons matched intake, rods/crank stock all ARP etc.... but I know the breaking point is around 600 hp so wen and if it breaks ill have Bison build me a stroker.

I'm ready to buy this 6870 but then I'm thinking will there be somthn else out between now and spring time? I was also looking at the Comp stuff and BW as well but I really like the Comp stuff and its really light. wat do u guys think? I'm not class racing so it will def be a 4 bolt setup.

 

[sackracing]

If I wasn't running TSM I would have the four bolt 68.

 

[forcefed3.8's]

I would like to do a 6766 .81 4 bolt on a street car. I think it would be a killer 8 sec capable turbo with little lag. Not sure about comp or bw as far as power vs lag. I know they both make some nice stuff.

 

[forcefed3.8's]

I wonder how the 6870 4 bolt would spool vs my 7675 now.