Porting and dimpling

[Bluezone]

I don't either overall. But I am really curious as to what the modelling will do with the advanced exhaust cam. I have suspicions, simply because the rear-wheel-drive platforms with the 3.5 EcoBoost, advance the exhaust cams. I'd be very interested see if this is one of the things that should be addressed with our cams.
I loving the 2JZ stuff that you're playing with right now. Makes me miss my Supra.

 

[802SHO]

You’re not going to be anywhere near my new time. I’ll continue to actually do things and make progress and you can continue to speculate and not contribute anything. It’s just really strange how forcing more air into my engine with turbos and nitrous how that poor stock cam does just fine. Equally strange how almost everyone expects to make more power with the same stock cams. I mean, if airflow up until the cam is for naught why do any of us bother? I’m being sarcastic.

My record was set with a stock motor so not sure what you mean, 15-20k to
be within a stock car? 15-20 to take it beyond that yes. 1 second is bus lengths though and it is what it is. You can get the gap lol!

 

[luigisho]

It is too heavy and the powertrain is completely ass backwards. I enjoy the banter of the forum, and enjoy gapping unsuspecting people at stop lights in a high 11 to low 12 second Taurus.

It has always been this from the beginning. Just tweak it how you like it, and enjoy it for what it is. Unless you have the urge to push it and deal with the carnage and put it back together again. Respect to those folks.

 

[Bluezone]

Sometimes applications of old practices can alleviate new problems. If turbine side and turbine are considered such a constriction to the exhaust flow. The use of old school adapters to allow the use of say gt25 turbos would probably alleviate the restrictions. Buying and installing said turbos it's left up to those who want to do it. Designing the adapter and having it made, I will leave up to the experts who foresee problems. When this is done I will worry about it.

 

[stripSHO]

You’re not going to be anywhere near my new time. I’ll continue to actually do things and make progress and you can continue to speculate and not contribute anything. It’s just really strange how forcing more air into my engine with turbos and nitrous how that poor stock cam does just fine. Equally strange how almost everyone expects to make more power with the same stock cams. I mean, if airflow up until the cam is for naught why do any of us bother? I’m being sarcastic.

My record was set with a stock motor so not sure what you mean, 15-20k to
be within a stock car? 15-20 to take it beyond that yes. 1 second is bus lengths though and it is what it is. You can get the gap lol!

Ok bro. I contribute more in a single insightful information post than you ever have or ever will. What's your great contribution? Blasting nitrous into your engine bay to make power??? HAHAHAHAHAHAHAHA sure. You have no clue what you're doing and don't have an iota of understanding about engine performance. You blindly spray and pray every single bolt on and ricer mod you've ever heard of and hope for the best. If anything, its guys like you gobbling up and promoting trash products that set the platform back by closing out market space for better offerings. RIP ATP turbos...

'Power adders work with stock cams, therefore big flowing heads must work too' is probably one of the most clueless statements I've ever heard. By all means, show me which part of the cylinder head "forces" more air into your engine! SMH stop, dude. You're cracking me up but you're making a fool of yourself. Your incessant ignorance is not justification for trying to prevent me or any other member from adding some much needed sound, DATA-DRIVEN reasoning to this forum.

This is my last time addressing your vapid arguments since you can't muster a legitimate case or
for your die-grinder-as-a-universal-and-omnipotent-magic-horsepower-wand theory like you so paradoxically pleaded for from everyone else. For that matter you can't seem identify or comprehend what you're really arguing against. There's nothing more annoying than having to listen to an absolute dumba.ss trying so hard to be a smartas.s. I have a record of stating that cams aren't the problem. I've argued it on this site, with people vastly more qualified than you, that the stock cams have much untapped potential. I've said many times that the turbos, specifically THE FACTORY TURBINE HOUSINGS are the problem. You, in this very thread, said the same thing! I'm showing you the cams and heads flow pretty damn good up to 7000 rpm. I'm showing you the 70 psi exhaust pressure you're up against. Yet for some unintelligible reason all you want to do is shout CAMS! CAMS! CAMS! at me like a kid on a short bus smacking his helmet against the window.

You know you have no idea what you're talking about. I know you have no idea what you're talking about. Anybody who picked up on your admission that you waited until after digging yourself into a hole of baseless opinion to start googling for anecdotal evidence knows you have no idea what you're talking about. So, if all you're here to do is mock me because you're butt-hurt that I'm not towing the line and feeding your confirmation bias, then please do us all a favor and find your way out of this discussion you Miley'd your way into so the grown-ups can go back to talking in peace.

 

[stripSHO]

Okay I will politely ask again. What would happen to your modelling if you advanced (set) the exhaust cam +2° to 5°?

Sorry brother it's been a busy couple days. None of that is modeled. That's actual performance. So I can't readily speak on theoretical exhaust timing. Though I do know that exhaust cam angles generally don't have a great impact on power. I believe Ford's decision to fit exhaust phasers on other models relates mostly to EGR requirements. Not necessary on the SHO with so much backpressure.

I only showed up to 14 psi since that's all my compressors are capable of maintaining out to redline. The graphs clearly show that when you keep the wastegate open, the engine breathes pretty dang good all the way to redline. This should surprise no one; the power curve of the NA 3.5L is much the same and NA models make peak HP at 6500 rpm and shift at like 6850 rpm. To the best of my knowledge they are the same cams.

Start commanding boost, and the exhaust pressure increases exponentially. Obviously an engine isn't going to breath very well if it has 70 psi exhaust pressure and only 14 psi at the intake. We're talking about a 4:1 back pressure ratio! It's hard for me to imagine there being much you can do to improve VE under those conditions. And the mechanical pumping losses during the exhaust stroke must get pretty severe. The dyno charts I've seen with one particular brand of aftermarket turbos suggest they might even be producing enough backpressure to float the exhaust valves near 6000 rpm. I don't know this for sure though.

So as more boost is commanded and the turbines choke off more and more, the power peak moves lower and lower, which means it takes more and more torque to a produce a given horsepower, which is just undue stress on the rotating assembly. Guys are out there bending rods needlessly. It only takes 450 ft-lbs to produce 550 horsepower at the engine's natural power peak of 6500 rpm. These things seem reliable at 500 ft-lbs and can obviously handle 7000 rpm, so > 600 whp out of the stock long block safely isn't a stretch of the imagination. The F150's do it all day, with at least one running 11.0's... in a 5000 lb truck.

It just takes someone with the ambition to fab custom headers and fit a turbo with a good aspect ratio. Or skip all that, run the stock turbos on wastegate and get a large (300-400hp) wet direct port nitrous kit with progressive control.

 

[802SHO]

Ok bro. I contribute more in a single insightful information post than you ever have or ever will. What's your great contribution? Blasting nitrous into your engine bay to make power??? HAHAHAHAHAHAHAHA sure. You have no clue what you're doing and don't have an iota of understanding about engine performance. You blindly spray and pray every single bolt on and ricer mod you've ever heard of and hope for the best. If anything, its guys like you gobbling up and promoting trash products that set the platform back by closing out market space for better offerings. RIP ATP turbos...

'Power adders work with stock cams, therefore big flowing heads must work too' is probably one of the most clueless statements I've ever heard. By all means, show me which part of the cylinder head "forces" more air into your engine! SMH stop, dude. You're cracking me up but you're making a fool of yourself. Your incessant ignorance is not justification for trying to prevent me or any other member from adding some much needed sound, DATA-DRIVEN reasoning to this forum.

This is my last time addressing your vapid arguments since you can't muster a legitimate case or View attachment 83189
for your die-grinder-as-a-universal-and-omnipotent-magic-horsepower-wand theory like you so paradoxically pleaded for from everyone else. For that matter you can't seem identify or comprehend what you're really arguing against. There's nothing more annoying than having to listen to an absolute dumba.ss trying so hard to be a smartas.s. I have a record of stating that cams aren't the problem. I've argued it on this site, with people vastly more qualified than you, that the stock cams have much untapped potential. I've said many times that the turbos, specifically THE FACTORY TURBINE HOUSINGS are the problem. You, in this very thread, said the same thing! I'm showing you the cams and heads flow pretty damn good up to 7000 rpm. I'm showing you the 70 psi exhaust pressure you're up against. Yet for some unintelligible reason all you want to do is shout CAMS! CAMS! CAMS! at me like a kid on a short bus smacking his helmet against the window.

You know you have no idea what you're talking about. I know you have no idea what you're talking about. Anybody who picked up on your admission that you waited until after digging yourself into a hole of baseless opinion to start googling for anecdotal evidence knows you have no idea what you're talking about. So, if all you're here to do is mock me because you're butt-hurt that I'm not towing the line and feeding your confirmation bias, then please do us all a favor and find your way out of this discussion you Miley'd your way into so the grown-ups can go back to talking in peace.

This isn’t a feud lol! You’re putting in way more thought and turning this into something it never was in your brain. You don’t have me cornered and I’m not even trying to (fight back)? Or whatever you think is going on. I could care less what you think your education is and what you think of mine. I didn’t (Miley) my way into anything. Talking about cams being the bread and butter of this engine is so far from true, while dismissing other avenues of power. Cute that you put in here you think the cams have a lot of untapped potential. I think the absolute best part about this whole back and forth is that even if you truly are smarter than me……I can’t tell! What good is knowledge when it’s not practiced? I don’t need to fully understand something to catch on to the main ingredients. I don’t need to be fully educated to be successful. And from the outside looking in it appears you have done less with more your whole life…..while I blissfully continue to do more with less and not lose any sleep over it. So now I’m going to have to ignore you, bc I know you will want to keep going back and forth for your amusement. If you want you can be called the Master of the back and forth. But after your snack and nap ok?

Nice chatting, be good, be safe and maybe spend more time off this site with real people in your life. Just a suggestion. Insert hug here.

 

[802SHO]

Well here is the Flow Data from the CNC port job. As Matt Pohnan stated stock and CNC ported heads flow passed camshaft max lift, so bigger camshafts would help but unfortunately there’s no aftermarket cam options as they are multi piece hollow camshafts.

 

[Bluezone]

Sorry brother it's been a busy couple days. None of that is modeled. That's actual performance. So I can't readily speak on theoretical exhaust timing. Though I do know that exhaust cam angles generally don't have a great impact on power. I believe Ford's decision to fit exhaust phasers on other models relates mostly to EGR requirements. Not necessary on the SHO with so much backpressure.

I only showed up to 14 psi since that's all my compressors are capable of maintaining out to redline. The graphs clearly show that when you keep the wastegate open, the engine breathes pretty dang good all the way to redline. This should surprise no one; the power curve of the NA 3.5L is much the same and NA models make peak HP at 6500 rpm and shift at like 6850 rpm. To the best of my knowledge they are the same cams.

Start commanding boost, and the exhaust pressure increases exponentially. Obviously an engine isn't going to breath very well if it has 70 psi exhaust pressure and only 14 psi at the intake. We're talking about a 4:1 back pressure ratio! It's hard for me to imagine there being much you can do to improve VE under those conditions. And the mechanical pumping losses during the exhaust stroke must get pretty severe. The dyno charts I've seen with one particular brand of aftermarket turbos suggest they might even be producing enough backpressure to float the exhaust valves near 6000 rpm. I don't know this for sure though.

So as more boost is commanded and the turbines choke off more and more, the power peak moves lower and lower, which means it takes more and more torque to a produce a given horsepower, which is just undue stress on the rotating assembly. Guys are out there bending rods needlessly. It only takes 450 ft-lbs to produce 550 horsepower at the engine's natural power peak of 6500 rpm. These things seem reliable at 500 ft-lbs and can obviously handle 7000 rpm, so > 600 whp out of the stock long block safely isn't a stretch of the imagination. The F150's do it all day, with at least one running 11.0's... in a 5000 lb truck.

It just takes someone with the ambition to fab custom headers and fit a turbo with a good aspect ratio. Or skip all that, run the stock turbos on wastegate and get a large (300-400hp) wet direct port nitrous kit with progressive control.

The EGR explanation makes sense. Yeah, if 70 PSI is in the exhaust it's going to cause a lot of problems.
From what you're saying I kind of wonder if the stock Springs can keep the intake valve closed at higher levels of boost and RPM as well. Though from what you're saying the F-150 seems to manage.
Another potential problem with advancing the exhaust cam is there's the potential of bending a exhaust valve against all that cylinder pressure. I just don't know.
From what I do understand, increasing the LSA can spool the turbos faster. Is that going to create more back pressure though? Again I don't know.
Thanks for the reply.

 

[802SHO]

Valve float is definitely going to happen pushing the stock motor hard. I’ve experienced on numerous occasion when I’m in 3 or 4th gear pulling hard, intermittent loss of power/compression. I’m assuming valve float and also strange exhaust pops. Matt Pohnan said the stock valve springs can be compressed with your fingers easily. One upgrade I’m excited about is the supertech valve springs I have now. Looking forward to not feeling a loss of power all the while hearing my engine roaring and giving it everything it’s got. I have some Dragy videos where you can see the loss of g force during the pull after the 1/8 that I can certainly feel and I can hear the engine seemingly going in and out of compression as it goes in and out of pulling/accelerating. Would that be a valve float symptom?

 

[stripSHO]

Well here is the Flow Data from the CNC port job. As Matt Pohnan stated stock and CNC ported heads flow passed camshaft max lift, so bigger camshafts would help but unfortunately there’s no aftermarket cam options as they are multi piece hollow camshafts. View attachment 83191

I'm very familiar. I saved it to my laptop when @bpd1151 posted it eons ago. I remember being puzzled why a guy would go chasing so much flow at .500" lift when there's only like .330" available. We don't race flow benches, and just about any well known expert will tell you that cfm numbers are the last thing they look at when evaluating a port design. The bench only shows theoretical maximums and is not at all an indicator of realized gains.

If you would, take a look at this video. Skip to the 16:00 mark if you're short on time.

They strapped the biggest, "best" flowing head on the engine and lost power. The big bad papa bear head performed identical to the little baby bear head. Momma bear head was just right for that combination. Why is this? Well, camshaft mainly. Heads that are designed to go beast mode at 8000 rpm aren't of any use on an engine that is timed to tap out at only 5400 rpm. Kinda like having a factory 3.5L head and cam combo that's optimized for 6500 rpm but has to tap out at 5400 rpm due to turbo choke.

On a basic porting where you don't mess with the valve size, I don't imagine it being likely to lose power unless it's a real butcher job. But realized gains aren't a given either. For better or worse, I'm a seeing is believing kind of guy. So until there's real world validation I'll maintain my stance while still being open to getting proven wrong.

 

[stripSHO]

Valve float is definitely going to happen pushing the stock motor hard. I’ve experienced on numerous occasion when I’m in 3 or 4th gear pulling hard, intermittent loss of power/compression. I’m assuming valve float and also strange exhaust pops. Matt Pohnan said the stock valve springs can be compressed with your fingers easily. One upgrade I’m excited about is the supertech valve springs I have now. Looking forward to not feeling a loss of power all the while hearing my engine roaring and giving it everything it’s got. I have some Dragy videos where you can see the loss of g force during the pull after the 1/8 that I can certainly feel and I can hear the engine seemingly going in and out of compression as it goes in and out of pulling/accelerating. Would that be a valve float symptom?

If it's happening at peak rpm, then definitely maybe. I tried once to press GH Matt why his turbos cause a swan dive in torque past 5500 rpm, and he blamed the cams. I asked what kind of exhaust manifold pressure his turbos operate at, and he never responded. Given how badly that guy loves to try and put me in my place, I found it telling that he didn't snap back with a response. I have to assume he either doesn't know, or doesn't want the answer getting out. Guys with ATP turbos didn't have that problem as far as I can tell.

BTW stumbling will greatly affect the output of virtual dyno. It's no different than any inertia dyno in that it's just reading revolutions per time squared against a known inertial load. On a dyno the roller is the load, on virtual dyno the vehicle mass is the load. Rollers dampen those types of fluctuations, but a tach signal straight from a data log does not.

 

[Bluezone]

It might be. Read this.

What is valve float?

help.summitracing.com

 

[802SHO]

If it's happening at peak rpm, then definitely maybe. I tried once to press GH Matt why his turbos cause a swan dive in torque past 5500 rpm, and he blamed the cams. I asked what kind of exhaust manifold pressure his turbos operate at, and he never responded. Given how badly that guy loves to try and put me in my place, I found it telling that he didn't snap back with a response. I have to assume he either doesn't know, or doesn't want the answer getting out. Guys with ATP turbos didn't have that problem as far as I can tell.

For me I believe it’s only when I’m spraying nitrous that that event occurs. It was great if it pulled all the way through which it did most of the time. I want to say it never happened without nitrous. As far as the porting there isn’t much else to talk about really until perhaps I or Mike can show (which I’m not sure how to present given all the other changes) how it works in unison with everything else. The data I was thinking would be for someone with CNC ported heads to go….you know I don’t think it helped or say..wow I think it does. Until it can be proven or not we’re just shooting the breeze and there’s plenty of experts talking it up and down. Essentially the debate could never stop.

I’m really really wanting to sell my Gen3R turbos and try something else. For the sake of just getting back on the road I could install them and bide my time until I get something else but part of me feels like that is just a waste of time to wait until then also. I’ve got plenty of room for a front turbo. The rear turbo is the question and how far off would it throw things if per say, an adapter was used and added some length and put a larger rear turbo in an better spot? I’m not sure but something like 58 mm precision turbo with .64 A/R, not sure if .82 A/R would be better. I was dreaming of just getting them attached to my current exhaust manifolds through either an existing or custom adapter to Vband, then to simplify things as much as possible even further than reusing the current exhaust manifolds to dump the exhaust out of the hood. Front turbo area im getting rid of the OEM fan, and my IC is up front so plenty of room there, it’s just how to maneuver the rear turbo and I was thinking why not relocate it with a longer adapter? Front turbo could hood exit the rear turbo could dump downward? I’d be happy if I didn’t have anything GearHead on my car for my own personal reasons.

Edit: I have their TC so never mind lol.

 

[Bluezone]

If it's happening at peak rpm, then definitely maybe. I tried once to press GH Matt why his turbos cause a swan dive in torque past 5500 rpm, and he blamed the cams. I asked what kind of exhaust manifold pressure his turbos operate at, and he never responded. Given how badly that guy loves to try and put me in my place, I found it telling that he didn't snap back with a response. I have to assume he either doesn't know, or doesn't want the answer getting out. Guys with ATP turbos didn't have that problem as far as I can tell.

BTW stumbling will greatly affect the output of virtual dyno. It's no different than any inertia dyno in that it's just reading revolutions per time squared against a known inertial load. On a dyno the roller is the load, on virtual dyno the vehicle mass is the load. Rollers dampen those types of fluctuations, but a tach signal straight from a data log does not.

I got thinking about how difficult it is to adjust the exhaust cam. So I looked up variable Cam timing and turbocharging. First hit was this article. It seems the tuner involved was retarding the intake Cam and advancing the exhaust cam at 4500 RPM.
Is it possible to make an adjustment in the intake cam timing tables so that the intake cam starts retarding say at 4500 RPM by 5-10°?

Spooling Up - Tuning DOHC Variable Valve Timing For Boost

Variable valve timing and its relationship to turbo performance is generally misunderstood. We cover the key effects of VVT and its benefits on a turbo engine.

www.enginelabs.com

EDIT: never mind, I checked, no power to be gained by retarding the intake cam at high RPM.

 

[802SHO]

If it's happening at peak rpm, then definitely maybe. I tried once to press GH Matt why his turbos cause a swan dive in torque past 5500 rpm, and he blamed the cams. I asked what kind of exhaust manifold pressure his turbos operate at, and he never responded. Given how badly that guy loves to try and put me in my place, I found it telling that he didn't snap back with a response. I have to assume he either doesn't know, or doesn't want the answer getting out. Guys with ATP turbos didn't have that problem as far as I can tell.

BTW stumbling will greatly affect the output of virtual dyno. It's no different than any inertia dyno in that it's just reading revolutions per time squared against a known inertial load. On a dyno the roller is the load, on virtual dyno the vehicle mass is the load. Rollers dampen those types of fluctuations, but a tach signal straight from a data log does not.

I put some logs into virtual dyno but the one I mentioned wasn’t with nitrous. I tried putting in a log from a nitrous drag strip run but the data was crazy like there was no way I made that much power, not even close. Although I didn’t believe the phenolic spacer killed that much power it made me wonder, and since I’ve removed it and sold it.

 

[stripSHO]

For me I believe it’s only when I’m spraying nitrous that that event occurs. It was great if it pulled all the way through which it did most of the time. I want to say it never happened without nitrous. As far as the porting there isn’t much else to talk about really until perhaps I or Mike can show (which I’m not sure how to present given all the other changes) how it works in unison with everything else. The data I was thinking would be for someone with CNC ported heads to go….you know I don’t think it helped or say..wow I think it does. Until it can be proven or not we’re just shooting the breeze and there’s plenty of experts talking it up and down. Essentially the debate could never stop.

I’m really really wanting to sell my Gen3R turbos and try something else. For the sake of just getting back on the road I could install them and bide my time until I get something else but part of me feels like that is just a waste of time to wait until then also. I’ve got plenty of room for a front turbo. The rear turbo is the question and how far off would it throw things if per say, an adapter was used and added some length and put a larger rear turbo in an better spot? I’m not sure but something like 58 mm precision turbo with .64 A/R, not sure if .82 A/R would be better. I was dreaming of just getting them attached to my current exhaust manifolds through either an existing or custom adapter to Vband, then to simplify things as much as possible even further than reusing the current exhaust manifolds to dump the exhaust out of the hood. Front turbo area im getting rid of the OEM fan, and my IC is up front so plenty of room there, it’s just how to maneuver the rear turbo and I was thinking why not relocate it with a longer adapter? Front turbo could hood exit the rear turbo could dump downward? I’d be happy if I didn’t have anything GearHead on my car for my own personal reasons.

Edit: I have their TC so never mind lol.

YESSS!!! YESSS!!! Now we're talkin'!

I know Precision is popular, but I personally would never buy a turbo from a manufacturer that can't supply a map for it. Especially at that price. It's just the meticulous planner in me. And if Precision's flow anything like a Garrett 58mm does, I think they'd do nothing but surge below 5500 rpm on this engine. On the other hand Borg Warners have a much wider operating range and a pair of S257SX-E would have better manners down to 4000 rpm and still be able to push up to 50 psi.

If you're not looking to be that ambitious, a pair of BW 52mm's (S252SX-E) would be incredibly happy at 30 psi and should still have enough umph to carry 45 psi out to 7000 rpm when you need them to. That's still gotta be at least 900 crank HP... . They'd also still be streetable and might stand a chance of still providing a decent 60' on foot braking. Not that you're worried about streetability anymore with a welded dif.

Then depending some things like converter slip, a single 76mm or 80mm could be a good fit too and meet your goals. Would definitely cost less in parts and fab. Just relocate the battery etc. and mount it over the transmission. Problem is you'd have to stay around 5000+ RPM after a shift or you risk surging the shit out of it. I know there's a guy out there running a single turbo on his SHO; I recall reading he was having a really hard time with it. Wonder if this is the reason why...

Keeping twin turbos would definitely be the superior way to go I think. Though good heads AND custom cams [don't hurt me! sorry!] could make it a different story as you wouldn't need as much boost to move the same air.

edit: DISCLAIMER: This not advice or a recommendation. I'm just a clown who spends too much time fiddling with MatchBot and nobody should listen to me.

 

[stripSHO]

I got thinking about how difficult it is to adjust the exhaust cam. So I looked up variable Cam timing and turbocharging. First hit was this article. It seems the tuner involved was retarding the intake Cam and advancing the exhaust cam at 4500 RPM.
Is it possible to make an adjustment in the intake cam timing tables so that the intake cam starts retarding say at 4500 RPM by 5-10°?

Spooling Up - Tuning DOHC Variable Valve Timing For Boost

Variable valve timing and its relationship to turbo performance is generally misunderstood. We cover the key effects of VVT and its benefits on a turbo engine.

www.enginelabs.com

EDIT: never mind, I checked, no power to be gained by retarding the intake cam at high RPM.

I do much the same- advance the intake for fast spooling off idle, then quickly snap back to zero overlap between 3000 and 3500 rpm. Can't say it's perfectly optimized, or that zero overlap is the absolute best operating point, but it works well enough for me so I've left it there. "zero overlap" is 10 degrees advanced from base according to my math and the information I have, but that might not be right either.

If you're interested in knowing, here's the factory "Optimum Power" cam phasing from my wife's NA Flex. Negative is advancing, Positive is retarding.


Oh and I just noticed your comment about intake valves holding against higher boost. Cylinder pressure never really goes lower than intake pressure, so I don't see how that could be a problem. I've read a million forum arguments about turbos causing valve float and they mostly end at this conclusion. But they're always focused on the intake and NEVER talk about the exhaust.

 

[stripSHO]

I put some logs into virtual dyno but the one I mentioned wasn’t with nitrous. I tried putting in a log from a nitrous drag strip run but the data was crazy like there was no way I made that much power, not even close. Although I didn’t believe the phenolic spacer killed that much power it made me wonder, and since I’ve removed it and sold it.

Ok so here's the thing with VD (ewww). The only thing it cares about in your data log is RPM. It looks at throttle position and when it sees WOT it starts calculating the rate of change in RPM. When WOT stops, it stops. Literally every other piece of information is disregarded. So you can't just feed it any file. You really need to give it a fixed gear pull just like you would on a real dyno. Feed it a big log full of stuff like a full 1/4 mile pass and it will go *******. I always clip just the timeframe I want to analyze and feed it that and it never does anything suspicious for me.

And of course make sure you select the correct gear, tire size, weight etc. in the software as those are all critical. The one other thing I will say is important is turn on the smoothing. If the chart looks like Six Flags then it's not any use. I leave my smoothing set at 6 all the time. It reports the lowest numbers that way, but I also feel like it makes any differences I observe more reliable.

As with any dyno, it is just a tuning tool. The absolute numbers don't matter, its the run to run variation that is of value. It doesn't matter to me how close its numbers match the dyno down the street, because the dyno down the street isn't going to match the one across town, or across the country.

 

[802SHO]

YESSS!!! YESSS!!! Now we're talkin'!

I know Precision is popular, but I personally would never buy a turbo from a manufacturer that can't supply a map for it. Especially at that price. It's just the meticulous planner in me. And if Precision's flow anything like a Garrett 58mm does, I think they'd do nothing but surge below 5500 rpm on this engine. On the other hand Borg Warners have a much wider operating range and a pair of S257SX-E would have better manners down to 4000 rpm and still be able to push up to 50 psi.

If you're not looking to be that ambitious, a pair of BW 52mm's (S252SX-E) would be incredibly happy at 30 psi and should still have enough umph to carry 45 psi out to 7000 rpm when you need them to. That's still gotta be at least 900 crank HP... . They'd also still be streetable and might stand a chance of still providing a decent 60' on foot braking. Not that you're worried about streetability anymore with a welded dif.

Then depending some things like converter slip, a single 76mm or 80mm could be a good fit too and meet your goals. Would definitely cost less in parts and fab. Just relocate the battery etc. and mount it over the transmission. Problem is you'd have to stay around 5000+ RPM after a shift or you risk surging the shit out of it. I know there's a guy out there running a single turbo on his SHO; I recall reading he was having a really hard time with it. Wonder if this is the reason why...

Keeping twin turbos would definitely be the superior way to go I think. Though good heads AND custom cams [don't hurt me! sorry!] could make it a different story as you wouldn't need as much boost to move the same air.

edit: DISCLAIMER: This not advice or a recommendation. I'm just a clown who spends too much time fiddling with MatchBot and nobody should listen to me.

Stay twin turbo. Those borg Warner’s aren’t too big for two? What would you do for wastegate? I was looking at Precision 11910 wondering how I would mount it and 3 boost references on it have me wondering what for. I don’t know Jack about reading turbo maps but definitely don’t want to something out of efficiency or surging.