[JV2391]

I currently have a 62-1, P-trim .68 a/r turbo (1099 + external JGS 38mm wastegate with a Dodge Stealth 3L, 6G72 engine (forged internals 9:1 CR). I would like to make this a "fun" street car. My estimate was for 500 whp, but I'm willing to sacrifice top end for a quicker boost build and response.

The turbo was part of an exhaust piping kit and I know the a/r is too big. the Turbonetics matrix suggests a .58 a/r for a 3L engine with a full T4 housing. I am keeping the T4 flange and do not plan to downsize to a T3 flange.

Questions:

1. What RPMs do you estimate for boost build and at 15psi for turbo (11000)?

2. Would Stage 5 turbo (11006) have a quicker boost buildup (slope + RPM)? by how much?

3. Do you still make turbo (11006)?


4. How much sooner would boost build with the ball bearing option turbo (11000-BB)?



I've called your help desk, but there has to be someone out there who could "estimate" RPM response times with a typical setup.

Thanks!

[Robert]

Originally Posted by JV2391

I currently have a 62-1, P-trim .68 a/r turbo (1099 + external JGS 38mm wastegate with a Dodge Stealth 3L, 6G72 engine (forged internals 9:1 CR). I would like to make this a "fun" street car. My estimate was for 500 whp, but I'm willing to sacrifice top end for a quicker boost build and response.

The turbo was part of an exhaust piping kit and I know the a/r is too big. the Turbonetics matrix suggests a .58 a/r for a 3L engine with a full T4 housing. I am keeping the T4 flange and do not plan to downsize to a T3 flange.

Questions:

1. What RPMs do you estimate for boost build and at 15psi for turbo (11000)?

2. Would Stage 5 turbo (11006) have a quicker boost buildup (slope + RPM)? by how much?

3. Do you still make turbo (11006)?


4. How much sooner would boost build with the ball bearing option turbo (11000-BB)?



I've called your help desk, but there has to be someone out there who could "estimate" RPM response times with a typical setup.

Thanks!

The problem with estimating boost threshold is that its not just displacement and compression ratio that dictate this. Theres exhaust manifold design, volumetric efficiency, cam profile (overlap and lift), the engines general exhaust flow and pulse characteristics, charge piping design, intercooler efficiency, pressure drop, wastegate respone, and about a thousand other factors that could affect boost threshold. That's likely why no one is going to guesstimate an engine speed boost threshold. All that being said yes a T3 Stage 5 turbine will spool up faster then a full T4 P trim as the turbine wheel is smaller. PErsonally I would start with a smaller P tirm turbine housing since you already have that unit and its much cheaper and quicker to expirment with different turbine A/Rs then to switch turbine wheels around.

[JV2391]

Thanks for the reply.

I had already ordered the .58 housing.

Granted there are many variables, but with a company of your experience, you should be able to ballpark for engine "x", turbo A (T4 Stage 5) will have these charateristics compared to turbo B (T4 P Trim).

I would be happy to get comparison info from any 3L V6 DOHC engine - just as long its an apples to apples comparision.


If not, how did you design these wheels and housings?

All trial and error? - I don't believe it.

As for the turbos listed in the "sticky" forum, which ones do you plan to discontinue? I'd still like to know all my options if the smaller housing does not work out.

[Robert]

Originally Posted by JV2391

Thanks for the reply.

I had already ordered the .58 housing.

Granted there are many variables, but with a company of your experience, you should be able to ballpark for engine "x", turbo A (T4 Stage 5) will have these charateristics compared to turbo B (T4 P Trim).

I would be happy to get comparison info from any 3L V6 DOHC engine - just as long its an apples to apples comparision.


If not, how did you design these wheels and housings?

All trial and error? - I don't believe it.

As for the turbos listed in the "sticky" forum, which ones do you plan to discontinue? I'd still like to know all my options if the smaller housing does not work out.

I'm not aware of any units planned for discontinuiation at this time. Ball parking is hard because motors are so different. For instance the 2AZ-FE Scion tC motor runs a T04E 50 trim compressor with a T3 Stage 2 turbine and a .48 A/R. Thats a 2.4 L motor and the turbo spools at just under 3,000 RPMs. The Nissan Sentra SE-R Spec V runs a QR25DE which is a 2.5L motor. Theortically if I wanted to ball park I could say that the same turbo would spool up about the same since there is only .1L difference in displacement. But in reality that isn't the case at all. The QR25DE motor runs a T04E 50 trim compressor as well but uses a T3 Stage 3 turbine with a .63 A/R. Thats a larger turbine wheel and a larger A/R housing for just .1 L of displacement difference. And the QR25DE makes full boost SOONER with the larger turbine and A/R. Why? The QR25DE has a much longer stroke. Its long rod length and subsequent bore/stroke ration will spool a larger turbo faster then the 2AZ-FE could ever spool a smaller turbine. Thats a perfect example of why its difficult to ball park a boost threshold number on displacement alone.