Twins what sizes?

[02StanGT]

I was going to purchase a hpp kit with the twin 57's and was told they would spool up nicely by about 3000-3500. My buddy has a hpp kit laying around that he was going to put on his mustang gt when he finally got his built block. Other than a sullivan intake I think he has everything I would need to slap on my cobra. So I have two questions, his kit came with ball bearing 67's. Will these still spool up by 3500 rpm so I can get into full boost quickly? And do you think his kit would work on a cobra? Hpp's kits are the same for a cobra anda gt right?

 

[eebj01]

If your car is stick shift and a street car, I would not recommend the 67's. I have a THP twin 67 kit with an automatic. The transmission was the deciding factor. A good torque converter will slip and get the rpm up quicker and then stop slipping to load the engine and spool the turbos. A stick car with 67's would be pretty shitty to drive on the street everyday. I would go in the 60-61 range if you are a street strip type of guy. If you like very fast throttle response and don't plan on running over 17 psi, go with 57's.

 

[Fuerza]

Why do you say go 57's if your not going to push them past 17psi?

 

[02StanGT]

Why do you say go 57's if your not going to push them past 17psi?

+1

 

[Blown04GT]

+2, I thought the 57s were good past that boost level? I just ordered mine so I hope so......I want to make 700 on pump and I don't know if 17 will cut it.....

 

[eebj01]

Why do you say go 57's if your not going to push them past 17psi?

In my opinion, 57's past 17 psi aren't as efficient as 61's. 61's will make more power at less boost with very moderate lag. Plus, most guys over 17 psi run race fuel unless you are going to run methanol. If you are going to run over 17 psi and racefuel often enough to justify, why wouldn't you go with the bigger turbos and run 24 psi and put down 850-900 rwhp? That's how I look at it. In my opinion, 57's are great for a street car on pump gas with a stick shift. They will spool right up, make great bottom end with good top end. You will put down 700 rwhp fairly easily while keeping the bottom end. Most will be happy with 57's. You can run more than 17 psi but it will become hotter boost to flow the necessary cfm of air. I like 61's for a stick car on the street where you don't mind a bit of lag because you are going to push it up top. For an automatic car, the 61's would take the place of the 57's for a street car. I have an automatic and went 67's because I like to push things. They are laggy even with the automatic and I couldn't imagine them with a stick. With the automatic though, they stay in boost through the shifts and it pulls great. If I let out of it due to tire spin or something, it takes a bit to fully spool up again. I can't imagine them with a stick tranny. I probably could have done 61's and gone just as fast at the track. The nice thing with the 67's for me is the air inlet temps. They are down in the 80's which is unbelievably cool. The turbos are actually totally inefficient under 30 psi. I have gone from 14-24 psi with the inlet temps staying between 78-82 degrees. At 27 psi they were 88 degrees. I would figure somewhere around 130-140 would be efficient. That's probably 32-35 psi. Not going to do that on a stock motor...at least this early in the year! If it was me, with a stick car, I'd go 61's with the upgraded intercooler from THP. Put down 850 rwhp on pump gas, 900+ pump gas with methanol, 950-1000 rwhp on race fuel.

 

[eebj01]

+2, I thought the 57s were good past that boost level? I just ordered mine so I hope so......I want to make 700 on pump and I don't know if 17 will cut it.....

Also, at 15 psi, I only made 735 rwhp through the automatic. I, the tuner who has a 2000 hp turbo SSO car, and Jim at THP all agreed that the turbos were too big and weren't in their efficiency range. We all believe that the car would have made more power with 61's. If we would have gotten aggressive and upped the timing and leaned it out a bit due to the cool inlet temps, they probably would have made alot more. What happens on a brutally hot day or a bad tank of gas or something? I just don't think 67's are useful on most street cars , especially with a stick shift, that's all. I think that the power left on the table due to lag alone makes them not worth it.

 

[Blown04GT]

Also, at 15 psi, I only made 735 rwhp through the automatic. I, the tuner who has a 2000 hp turbo SSO car, and Jim at THP all agreed that the turbos were too big and weren't in their efficiency range. We all believe that the car would have made more power with 61's. If we would have gotten aggressive and upped the timing and leaned it out a bit due to the cool inlet temps, they probably would have made alot more. What happens on a brutally hot day or a bad tank of gas or something? I just don't think 67's are useful on most street cars , especially with a stick shift, that's all. I think that the power left on the table due to lag alone makes them not worth it.

so what do you think the 57's will make at 15psi through the T56?

 

[Fuerza]

In my opinion, 57's past 17 psi aren't as efficient as 61's. 61's will make more power at less boost with very moderate lag. Plus, most guys over 17 psi run race fuel unless you are going to run methanol. If you are going to run over 17 psi and racefuel often enough to justify, why wouldn't you go with the bigger turbos and run 24 psi and put down 850-900 rwhp? That's how I look at it. In my opinion, 57's are great for a street car on pump gas with a stick shift. They will spool right up, make great bottom end with good top end. You will put down 700 rwhp fairly easily while keeping the bottom end. Most will be happy with 57's. You can run more than 17 psi but it will become hotter boost to flow the necessary cfm of air. I like 61's for a stick car on the street where you don't mind a bit of lag because you are going to push it up top. For an automatic car, the 61's would take the place of the 57's for a street car. I have an automatic and went 67's because I like to push things. They are laggy even with the automatic and I couldn't imagine them with a stick. With the automatic though, they stay in boost through the shifts and it pulls great. If I let out of it due to tire spin or something, it takes a bit to fully spool up again. I can't imagine them with a stick tranny. I probably could have done 61's and gone just as fast at the track. The nice thing with the 67's for me is the air inlet temps. They are down in the 80's which is unbelievably cool. The turbos are actually totally inefficient under 30 psi. I have gone from 14-24 psi with the inlet temps staying between 78-82 degrees. At 27 psi they were 88 degrees. I would figure somewhere around 130-140 would be efficient. That's probably 32-35 psi. Not going to do that on a stock motor...at least this early in the year! If it was me, with a stick car, I'd go 61's with the upgraded intercooler from THP. Put down 850 rwhp on pump gas, 900+ pump gas with methanol, 950-1000 rwhp on race fuel.

Thanks for posting, I plan to keep the 6 speed in my car, so 57's for me. When I spoke to Turbochargedpower they recommended the 57's. People on this board have posted high 600's on 15psi with twin 57's. That seems like more than enough for me, especially with pump gas.

 

[Turbo98]

Put down 850 rwhp on pump gas, 900+ pump gas with methanol, 950-1000 rwhp on race fuel.

Wow. I didn't realize the 61's put down that kind of power. In looking at a compressor map for a 60 trim T04E compared to the one for the 57's, they don't make that much more overall power. With the 60, at 20 PSI, the map shows 500fwhp max each at 60% efficiency. With the 57, at 21 PSI, they max out at 450fwhp at the same 60% efficiency. I know you can push them out to 40% efficiency and make another 50fwhp or so but for comparison purposed, I just don't see a large difference in max power. If you push them out to 550HP and 500HP respectively, that would be 850rwhp and 935rwhp. Yeah the 60's make more but to me, it doesn't seem worth the extra spool for a stick car. I don't claim to be a turbo expert but maybe I'm missing something here.