Recommendation on a Precision Turbo?
Feb 19, 2014 | 12:48 PM
#12
So I'm pretty sure I'm going to go with the PT7675. It is capable of 1,200 horse at the crank which will be plenty for me. Since this is also a street truck, I would rather have a turbo on the smaller side of the scale for the responsiveness, and it should also make my power goal. I've been doing a little more looking around and it makes sense. Two unrelated companies told me the same one, and they know way more than I do. I am also waiting on a reply from one more.
This page on turbonetics' site also backs up my thinking and on the turbo matrix.pdf linked at the bottom, a 76mm is what they say will make my goal also.
This page on turbonetics' site also backs up my thinking and on the turbo matrix.pdf linked at the bottom, a 76mm is what they say will make my goal also.
Feb 19, 2014 | 01:47 PM
#13
Good thread. I would be in the same position. Spend 1500 on a turbo and find out its not the ideal turbo for your goals and setup.
trick puts an 80mm with his 6.2 stage 5 kit. which is 378 litres. Your 402ci is 6.6 litres are I would say with it being a built motor with a goal of 700+, an 80 would be a good choice. Find guys that have over 400 inch cubes and what turbo they use, im sure they have vids of pulls and dynos. see which ones fit your rpm sweep.
Its def worth the investment of researching before the purchase. Do it for yourself and all of us reading. Good luck cause I would be pissed if i bought a turbo and it didnt make boost till its reved to the moon, or it makes boost off idle and chokes out at 5K rpm.
trick puts an 80mm with his 6.2 stage 5 kit. which is 378 litres. Your 402ci is 6.6 litres are I would say with it being a built motor with a goal of 700+, an 80 would be a good choice. Find guys that have over 400 inch cubes and what turbo they use, im sure they have vids of pulls and dynos. see which ones fit your rpm sweep.
Its def worth the investment of researching before the purchase. Do it for yourself and all of us reading. Good luck cause I would be pissed if i bought a turbo and it didnt make boost till its reved to the moon, or it makes boost off idle and chokes out at 5K rpm.
Feb 20, 2014 | 09:23 AM
#18
I don't mean to be stubborn about this, I just want to understand the "why". The 7675 is rated to 1,200 hp, why should I go bigger? Can you guys explain a little further? What I am I missing? I like this excerpt from turbonetics.
POWER:
• Think in horsepower not boost.
• Boost is just a number that you will have to run on your engine to make a certain horsepower.
• How much power do you want to make? Be realistic, the more accurate that you are, the better tuned your forced induction system will be.
• Can your vehicle (not just the engine, but the entire setup) handle such power?
• Remember the turbocharger is generally not the weakest link.
•Forged pistons, connecting rods, head studs, etc.
• “As much as possible” is not a goal.
INTENDED USAGE:
• What are you using the vehicle for?
• Race or street use?
• The way that you will be using the vehicle dramatically changes the sizing of the turbocharger and intercooler needs.
• Your choice of transmission type and gearing will greatly affect the performance and characteristics of the turbocharger, keep this in mind.
REMEMBER TO CHOOSE WISELY:
Most street/autocross/drift enthusiasts will prefer a smaller turbocharger due to its fast response. A turbo system equipped with a smaller turbocharger is generally considered more fun to drive. The tradeoff is the final power output of the setup. On another note, dedicated track cars are aimed for peak power over boost response. There’s no doubt track cars spend more time in the upper RPM than average street cars. So, a small sacrifice in boost response is offset by the huge power potential. Larger frame turbochargers are preferred by track car owners due to their maximum power capacity. For most street applications the best solution for selecting turbine wheels and turbine housings, is to choose the smallest wheel diameter available that meets the horsepower level wanted.
• Think in horsepower not boost.
• Boost is just a number that you will have to run on your engine to make a certain horsepower.
• How much power do you want to make? Be realistic, the more accurate that you are, the better tuned your forced induction system will be.
• Can your vehicle (not just the engine, but the entire setup) handle such power?
• Remember the turbocharger is generally not the weakest link.
•Forged pistons, connecting rods, head studs, etc.
• “As much as possible” is not a goal.
INTENDED USAGE:
• What are you using the vehicle for?
• Race or street use?
• The way that you will be using the vehicle dramatically changes the sizing of the turbocharger and intercooler needs.
• Your choice of transmission type and gearing will greatly affect the performance and characteristics of the turbocharger, keep this in mind.
REMEMBER TO CHOOSE WISELY:
Most street/autocross/drift enthusiasts will prefer a smaller turbocharger due to its fast response. A turbo system equipped with a smaller turbocharger is generally considered more fun to drive. The tradeoff is the final power output of the setup. On another note, dedicated track cars are aimed for peak power over boost response. There’s no doubt track cars spend more time in the upper RPM than average street cars. So, a small sacrifice in boost response is offset by the huge power potential. Larger frame turbochargers are preferred by track car owners due to their maximum power capacity. For most street applications the best solution for selecting turbine wheels and turbine housings, is to choose the smallest wheel diameter available that meets the horsepower level wanted.
Thanks Atomic, I will check more into the S480. I've seen that's a popular one between here and ls1tech.
Feb 20, 2014 | 10:39 AM
#19
Retail in a 76/75 is 1599.99
In pt88 is 1699.99
The 1200 hp is just a rating.
You would need to push around 25 psi to get to that point.
The only reason to go larger has nothing to do with the compressor side.
The exhaust side is more important in my opinion in bigger engines.
In pt88 is 1699.99
The 1200 hp is just a rating.
You would need to push around 25 psi to get to that point.
The only reason to go larger has nothing to do with the compressor side.
The exhaust side is more important in my opinion in bigger engines.
Feb 26, 2014 | 08:51 AM
#20
Ok, I'm 95% sure I'm going with the PT88 now. I pestered the shop a little more about how you guys are all saying the 7675 isn't large enoug on exhaust. After hearing the exact details on my engine (again), they now agree. They've got a freshly rebuilt turbo that came off one of their shop cars that I'll most likely be grabbing. They're asking $1,000 and we'll see if I can get it for less.