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Just dropped off my hot side to get ceramic coated and next thing I'll be pulling the trigger on is the turbo. I was about 90% set on a CEA 7675 .96AR but lately I've been talking to some guys who rave about BW turbos. My goal is 750-800rwhp through a 2v auto. Does anybody have any thoughts or opinions? I have a CF Fab hotside with single WG provision for a PTE 46mm. The flange on my hotside is a T4 open flange. It looks like the BW turbos are twin scroll...is it even possible to run a twin scroll turbo on a single scroll flange and 1 WG?
 

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Yeah you can run a twin scroll exhaust housing on an open flange with only one gate. The downfall is that you won't be taking advantage of the twin scroll feature is all. What's your displacement? If it's a dedicated street car with less than 350ci then I'd say stay with the CEA as that turbo lights off really quick.
 

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I run a BW S400SX3 82 with FMW and race cover now and had a PT7675CEA before. I only picked up some with the BW even though it is much bigger and has good parts.

I notice the spool is slower and the air is hotter.

I'm swapping to a gen2 pro mod 85 Precision when the local tracks go cold for the winter. I hope it is better.
 
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Yeah you can run a twin scroll exhaust housing on an open flange with only one gate. The downfall is that you won't be taking advantage of the twin scroll feature is all. What's your displacement? If it's a dedicated street car with less than 350ci then I'd say stay with the CEA as that turbo lights off really quick.
It's just a 2v Romeo iron block bored .030. Good info on the flange setup, and I agree I think I've about 99% decided to go with the 7675 with .96 AR
 
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I run a BW S400SX3 82 with FMW and race cover now and had a PT7675CEA before. I only picked up some with the BW even though it is much bigger and has good parts.

I notice the spool is slower and the air is hotter.

I'm swapping to a gen2 pro mod 85 Precision when the local tracks go cold for the winter. I hope it is better.
Good info man. How did you like the 7675 CEA? I'm about 99% set on that
 
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Good info man. How did you like the 7675 CEA? I'm about 99% set on that
The PT7675CEA spooled almost instantly on my car with a 363 or a 347 engine. It would make 20 psi boost in about 1 second off a fast idle. I didn't even have to use a bump box. I would just stage and put it on the floor. It would make target boost before I let go no matter how fast the tree activated.

That gave much more control of the important first few feet. I could dial the boost and shape the ramp to whatever the track and tires would hold. It also ran the same ET over and over, almost like a bracket car.

The BW takes a couple seconds to spool, even on the trans brake, and the air is a lot hotter at the same boost. It makes 3 MPH more, but isn't as consistent at getting to targeted boost until high gear.

That's why even though my MPH came up a few MPH the BW turbo is less consistent. Both turbos, however, have a lot of back pressure. The larger BW is over 50 psi hot side pressure for 25 psi boost. I couldn't measure when I was running the 7675CEA, but it had to have been much worse.

These were big solid roller cam 7500 RPM engines with fairly good heads. In the low 1000 HP range. Frankly, I wouldn't run another S400 series. I'd get another Precision, mostly because of boosted air temperature.
 

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I run a BW S400SX3 82 with FMW and race cover now and had a PT7675CEA before. I only picked up some with the BW even though it is much bigger and has good parts.

I notice the spool is slower and the air is hotter.

I'm swapping to a gen2 pro mod 85 Precision when the local tracks go cold for the winter. I hope it is better.
Nice! That's a serious turbo for sure. Now if we can just get this weather to cool off, it's still mid 80s here in AL. I saw you posted on the Phenix City dragstrip FB page awhile back, how often do you make it there? That track is 18 miles from me.
 

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The PT7675CEA spooled almost instantly on my car with a 363 or a 347 engine. It would make 20 psi boost in about 1 second off a fast idle. I didn't even have to use a bump box. I would just stage and put it on the floor. It would make target boost before I let go no matter how fast the tree activated.

That gave much more control of the important first few feet. I could dial the boost and shape the ramp to whatever the track and tires would hold. It also ran the same ET over and over, almost like a bracket car.

The BW takes a couple seconds to spool, even on the trans brake, and the air is a lot hotter at the same boost. It makes 3 MPH more, but isn't as consistent at getting to targeted boost until high gear.

That's why even though my MPH came up a few MPH the BW turbo is less consistent. Both turbos, however, have a lot of back pressure. The larger BW is over 50 psi hot side pressure for 25 psi boost. I couldn't measure when I was running the 7675CEA, but it had to have been much worse.

These were big solid roller cam 7500 RPM engines with fairly good heads. In the low 1000 HP range. Frankly, I wouldn't run another S400 series. I'd get another Precision, mostly because of boosted air temperature.
Thanks again for all of the info. It's always nice reading first hand experiences
 

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Nice! That's a serious turbo for sure. Now if we can just get this weather to cool off, it's still mid 80s here in AL. I saw you posted on the Phenix City dragstrip PB page awhile back, how often do you make it there? That track is 18 miles from me.
I was there a month ago making the first passes on a temporary engine. I'm just now getting that tune worked out.

I've got a DOT street legal radial tire race Saturday at Twiggs. Has to be fully DOT legal. There was a nice 65 Mustang from Alabama at Twiggs last race.
 
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TOMR what size crossover are you using? Have you ever used a 2.5 or 3 inch to fix back pressure issues? Also what are you suing to measure the back pressure? Always great advice from TOMR. Thank you for the replys
 

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TOMR what size crossover are you using? Have you ever used a 2.5 or 3 inch to fix back pressure issues? Also what are you suing to measure the back pressure? Always great advice from TOMR. Thank you for the replys
I had a complex wastegate issue I just fixed. I'll get into that, but I never would have found the issue without data logging hot side pressure and looking at how that compared to dome pressure and dome pressure solenoid switching times.

I still have the back pressure issue. At 21 psi boost my data log shows my hot side was 42 psi and the dyno said about 1100 RWHP.

I run a 10 psi boost spring and apply dome pressure with CO2 to get target boost. I use the Holley HP internal controller, generally ramping dome CO2 to to get 22 psi dome CO2 which makes 26 psi boost and 55 psi hot side.

This is what I missed that might help other people. Part of the reason I missed this was I started to believe my engine load affected boost. Before I could log hot side pressure, I just believed my boost would wobble around and be a 3-4 psi lower in low because of engine load. I thought, based on what I read on forums, my 4.10 gear and 6500 stall just wasn't loading the engine, because on shift and toward the end boost would creep up to 26-27 psi when it was only 20 in all of low gear.

You know, you read that stuff a turbo needs a 3.08 gear often enough and start to believe it.

When I finally looked at my data, I saw the hot side pressure average (not pulses) was jumping all around. That made me look at dome, and the dome was jumping all around. That made me look at the solenoids, and the solenoids were charging and bleeding the dome. This was doing two things. My launch might hit at 10 psi or 18 psi, and my boost would wobble, build different in different gears, and drift a couple psi.

Turned out my exhaust pulses pushing on the gate valve rattled the diaphram, and that translated into very fast pressure pulses on the dome pressure sensor. The pulses were at the exhaust pitch, around 400 pulses per second. The Holley only randomly samples the sensor, because it is busy doing lots of tasks. If it sampled the sensor on a peak, it would think the dome was way too high. It would command a bleed and reduce CO2. Then it would read too low, and command more CO2. This would rapidly open and shut the waste gate, causing erratic hot side pressure.

Because of inertia in the turbo, the quick pulses would smooth out. Since the pulse rate changed with RPM in gears, things got more stable with the slow increase when in high. This made my gate stay closed better, although still chattering, in high.

Holley had recommended a dome sensor PID setting of 0 on D term. D is the response smoothing. I bumped it up to 30 and all of that went away. Now my boost is just within 1 psi of whatever I dial. I can dial 20 psi on the line, and it is 20. I can dial 10 psi on the line, 20 psi starting in .2 seconds, and it is right at 20 psi in .4 seconds and stable. Now I can set it for 21 psi after launch and it goes to 21 psi and sits there in low and high.

The data log shows steady average dome pressure and steady hot side average pressure now, with normal exhaust pulse peaks. I still have excessive pressure, but it is stable.

The odd thing about this is after fixing this, the car is smoother and faster. With 10 psi launch and 21 psi all down track, it ran .2 seconds and 4 MPH faster then with 26 psi down track and the low gear variation. The average power must be way up.

None of this speaks well for me. I should have done this a year ago, when I first switched to the turbo. It took me exactly one year to get off my chair. :)
 

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So what crossover size do you use? LOL... Glad you discovered what the issue was.
 

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So what crossover size do you use? LOL... Glad you discovered what the issue was.
2.5 now. My choke point is the turbo.
 

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2.5 now. My choke point is the turbo.
Oh I agree, I was just wondering. I am using a 2.5 also. Sounds like you did your homework for sure. So TomR I started a thread about my combo, if you get time please chime in. I would love to hear your thoughts or suggestions.

Doug
 
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