O-Ring Question
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O-Ring Question At what point would you consider o-ringing the block important? 14 psi 18 psi or 20+
As this project has taken shape, I have dicarded the single turbo idea (lots of reasons why) and am now using twins. The motor is a forged aluminum 391, ARP studs top and bottom, 8.1:1 compression with twin T74 GTS turbos.
I am likely to run around at 14 psi on the street but will likely try to push 20-22 psi at the track. I was wondering if it was better to ring the heads or the block and how this would affect normal day to day operation?
As this project has taken shape, I have dicarded the single turbo idea (lots of reasons why) and am now using twins. The motor is a forged aluminum 391, ARP studs top and bottom, 8.1:1 compression with twin T74 GTS turbos.
I am likely to run around at 14 psi on the street but will likely try to push 20-22 psi at the track. I was wondering if it was better to ring the heads or the block and how this would affect normal day to day operation?
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From: Toronto, Canada
Until it's dynoed I'm not sure what it will make, however conservative goals are 650-700 in street trim and 850+ at the track.
The math says the car will make signifigantly more power however these days I err way low on the side of caution.
If it's any help the block is a resleeved 4.010 bore with a Callies 3.875 crank, Eagle rods, Ross pistons etc. It was built with high boost in mind.
The math says the car will make signifigantly more power however these days I err way low on the side of caution.
If it's any help the block is a resleeved 4.010 bore with a Callies 3.875 crank, Eagle rods, Ross pistons etc. It was built with high boost in mind.
With that level of HP, why do you want to run twin 74GTS. That sucker will be a lag monster. I would go with a set of lightweight shaft Master power T70's or even a pair of PT61's. A pair of T66's on a 383 LT1 doesn't hit full boost till about 5000rpms...hehe.
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Based on PTE and Garrett conversations, they both feel there will be virtually no lag because of the motor displacement. I already have the T74's but am using a smaller .85 housing to reduce lag even more. The car is not designed to see big RPM and I'm looking to peak in the area of 6400 rpm.
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Eh??...PTE is way off....lol. A pair of 74GTS's won't see full boost (peak torque) till 6000rpms or later. Here is a dyno sheet of a 383 LT1 with much smaller GT40's...hehe. Full boost wasn't till ~5600 rpms.
Jose
Jose
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Originally Posted by ls1290
Anything over 12 to 13 pounds, I would have the block or heads O-ringed.
my car sees 20psi on pump gas/meth on stock mls gaskets.. but never mind me just pay attention to the black firehawk with the scratched up bumper.
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Damn, this turbo stuff still gives me headaches. I tried the single T74, way too small and stalled at 5000 rpm big problems, The GT42R physically too big and barely enough as a single. JZ, not arguing just telling you what I have been told.
My motor has a requirement of 110 ft/min of airflow to support it. The GT42R was rated at 100 ft/min and it was recommended at minimum I should probably consider a GT60R to support the flow requirement, once again even bigger physically so, a no go.
Speaking with PTE I sent back the 42R and they replaced them (No Charge) with their recommended turbo for a twin set up. The T74 GTS will support up to around 800 HP alone and no, 2 doesn't guarantee up to 1600 HP. Based on the math my motor should reach full boost at about 3000 rpm and carry it well into the maximum RPM range. Theoretically the car should be capable of about 1100 RWHP at 6400 rpm ( not to say it will, too many other factors)
In my case PTE suggested these turbo's and offered to replace them if they don't work. From my understanding, excessive lag is part of that deal. The result should be very apparent even after a couple of dyno pulls. As far as PTE was concerned, and they stand by the 74 choice it is better and easier to downsize if needed than fight the car the other way. It will certainly be interesting to see what actually happens when all is said and done.
These turbo's are mounted ala Incon style so the exhaust to turbo is fairly short.
My motor has a requirement of 110 ft/min of airflow to support it. The GT42R was rated at 100 ft/min and it was recommended at minimum I should probably consider a GT60R to support the flow requirement, once again even bigger physically so, a no go.
Speaking with PTE I sent back the 42R and they replaced them (No Charge) with their recommended turbo for a twin set up. The T74 GTS will support up to around 800 HP alone and no, 2 doesn't guarantee up to 1600 HP. Based on the math my motor should reach full boost at about 3000 rpm and carry it well into the maximum RPM range. Theoretically the car should be capable of about 1100 RWHP at 6400 rpm ( not to say it will, too many other factors)
In my case PTE suggested these turbo's and offered to replace them if they don't work. From my understanding, excessive lag is part of that deal. The result should be very apparent even after a couple of dyno pulls. As far as PTE was concerned, and they stand by the 74 choice it is better and easier to downsize if needed than fight the car the other way. It will certainly be interesting to see what actually happens when all is said and done.
These turbo's are mounted ala Incon style so the exhaust to turbo is fairly short.
That black Firehawk runs 6.0 MLS head gaskets and has no o-rings unless Matt has changed stuff.
For 850rwhp you need a ton of other stuff I would not worry about that power level right this second.
For 850rwhp you need a ton of other stuff I would not worry about that power level right this second.
Originally Posted by Warbird
These turbo's are mounted ala Incon style so the exhaust to turbo is fairly short.
FWIW, from a roll (say 3k punch) my 66's (ball bearing) take a solid 1.5 to 2 seconds to spool. .69 A/R hot side, verter stalls about 3100 without any boost.
Of the T-brake, who cares. It's at 5800 once the button releases
Originally Posted by Pro Stock John
That black Firehawk runs 6.0 MLS head gaskets and has no o-rings unless Matt has changed stuff.
For 850rwhp you need a ton of other stuff I would not worry about that power level right this second.
For 850rwhp you need a ton of other stuff I would not worry about that power level right this second.
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Yeah,
PSJ
I'm not completely sold on o-ringing. If that black Firehawk can run MLS gaskets, I really can't see why I would have a problem.
Everything under the car around the car and mechanically is already built. Steel driveshaft, blueprinted tranny, 12 bolt, k-frame etc etc.
y2khawk
Yes the T74 fits under there and is not the lowest part of the car.
The place I see the biggest potential problem is the twin intercoolers, I have heard they can be a bottleneck. However, I do have a front mount single left over.
As to spool, we shall see, you guys know better than I. I would hope the six speed would reduce lag over an auto, who knows.
PSJ
I'm not completely sold on o-ringing. If that black Firehawk can run MLS gaskets, I really can't see why I would have a problem.
Everything under the car around the car and mechanically is already built. Steel driveshaft, blueprinted tranny, 12 bolt, k-frame etc etc.
y2khawk
Yes the T74 fits under there and is not the lowest part of the car.
The place I see the biggest potential problem is the twin intercoolers, I have heard they can be a bottleneck. However, I do have a front mount single left over.
As to spool, we shall see, you guys know better than I. I would hope the six speed would reduce lag over an auto, who knows.
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I'm still unsure about the o-ringing and now I'm a little concerned about how this thing is going to spool. It's kind of hard to argue with Harlan when he's out there doing it and showing how one of these systems can work.
I'm going to stick with the T74 for now and see what happens. On the bright side I at least know I won't have clearance issues if I have to downsize turbos at the end of the day
I'm going to stick with the T74 for now and see what happens. On the bright side I at least know I won't have clearance issues if I have to downsize turbos at the end of the day
