if you moved your coolant pipes, you could have the header pipes orientated up towards the hood instead of down towards the steering rack.

then maybe you could mount the turbos above the motor mounts.

or if your rebuilt your frame rails you could mount the turbos higher.

Hopefully there will be a decent HI boost 3.5L VQ with tube manifolds to compare with XKRs cast soon.

 

A manifold with short tubular runners would be bad ***!

 

Lots of information in this thread, some good and some bad. Rather than picking it all apart, I'll just add in my .02.

To keep things short, there is a reason we chose to run our hand made tubular manifolds. We wanted to maximize power and used what we learned in the Supra world to create our TT kit.

For optimal efficiency and power potential, tubular is the only way to go. Cast manifolds are fine for someone who wants a "kit" and a low price but for the true perfectionist, they will never be happy. My brother has cast Mike Smith manifolds on his 300ZX and absolutely hates them. He will be having custom tubulars made soon now as a result.

The easiest way to think about why a cast manifold isn't optimal is by simply imagining the exhaust pulses leaving the combustion chamber and instantly running into a wall and having to change direction. Then also imagine the large abrupt differences in the runner length. This all contrbutes to an inefficient setup.

As for the twin scroll question, it has pretty much been answered. Unless running a single setup, it wouldn't work since you cannot divide 3 runners (on one bank) into the two divided portions of a twin scroll turbo.

OP- Why did you tag the thread with 6765? The Precision 6765 only comes as an open scroll. We have recently sourced divided turbine housings for these particular turbo.s

Reid

 

^^^^^ If I remember correctly... I don't remember anyone saying that Tube manifold was not the best. Placement is what the discussion turned to.

So I guess I am not considered a "True Perfectionest" because I chose to use Cast because it allowed the best way to position my turbos to limit lag.

Like I said before... There are many of us on here that put performance before money. Meaning... We want the best no matter what it cost.

I have also said that if the Tube setup that SP or SFR has could position the turbos closer to limit lag...thats the route I would have taken.. The Madscientist installed one of your kits... Sharif has also.... So I am well aware of what's involved.

What would a custom Tube Manifold cost... $5000...$10000???? I assure you that when I did this last build I was not looking to do just any build or install the cheapest turbo kit..I would have paid anything if there was a better manifold to have the turbos sit on the position they are now.

I now know first hand how important turbo placement is... Veryyy costly lesson. Once again... If I was just looking for a highway beast or drag car... Placement would not matter to me.

So in closing... EVERYONE that has posted here is well aware that Tubular flows better than Log manifold...but the best does not always offer everything a customer is looking for.

 

i think you are overworrying about the lag...probably needs to rev more, BUT in any case the lag part, wouldn't it be more a function of the size of turbo and the displacement of your engine?

there is still some other stuff that i disagree...again... you compensate with boost and size up the turbo depending on your displacement for kind of lag you want.... it seems like your statement doesnt fully match your orginal goal or reaching 1000+whp on a DJ...
I do agree with your IN close statement...fair enough... you use whatever parts suit what you are looking from your build.... but when i started arguing here was to directly address the issue that people looking to maximize power they should NOT be pussified(no pun) with statements that" it cant fit", "not needed for our cars"...etc....

 

Thats what I am wondering as well. Lag has more to due with the size and a/r of the wheel than the mani....

A log vs an "equivalent" tube header will change lag what......10%, but an a/r change or a bigger/smaller wheel can change it what 50%.

I have a tubular setup with journal bearing turbos (everyone tells me they are large but they are only 54mm) and there is little lag (of course its impossible to eliminate it all unless we run teeny weeny turbos).

What is the advantage to instantly spooling turbos that make 100000ft-lbs of tq at 2000rpm anyway when the traction control setup is going to have to cut back all that to maintain grip?

I just think the concesus for all this is.....
If you want to make XXXXhp go with the shops that have done it.
If you want bling under the hood, get a PL single or a powder-coated Vortec.

Mike you don't have to defend your choice (beleive me, I got flogged on PM's once my car was done with the questions like: "why did you do this when shop2 does this which must be better?" etc)
Just get out there and start enjoyin it!!!!

Tom

 

Exactly...... Meaning on a road course I would have to shift to second gear where third gear would be the norm to prevent bogging....

As far as displacement and turbo size.... I thought the same... But on my other build turbo/manifold could not over come placement.... That's why I had to test drive that TT Lambo. Same company did his build... And he had the same spool up as a 700bb with way bigger turbos. Has turbos sit right up on the motor where mine sits out to the side and to the rear.

I was told it had to be place there or up high where it would be the first thing you see when the hatch is opened.... That way I would get the same spool up as the lambo.... It should be completed in 3 weeks so I will see.

 

Tom.... Don't get me wrong... I am not defending my setup or knocking others... I thought the same about A/F or turbo size..... But it seems that distance and placement plays a part in all this.... The way it was explained to me is when the turbo is repositioned with a shorter setup it will have a better spool.... It's not costing me so I will go with it.


Edit**** Jorge and Tom.... Remember now ... I am talking about a balance of big power and streetable.... Not just any power level. Remember what I am looking for... Over 800 whp DD that could be driven on the street with ease and on any track/ Event....

 

I understand completely. I went with a "smaller" setup. But due to the ability of Precision Turbos to flow at high rates and high boost numbers, it made sense to have tubular headers due to exhaust pressure vs intake pressure due to high boost numbers.

I do wonder where mine would run outta steam as is (maybe 850rwhp on SP's Mustang dyno). With few changes we are doing it will easily do 850rwhp (and probably on less boost than I need now)....don't know if I'll ever run it up quite that high, streets around here SuCK so lots of hop/bounce due to poor asphalt/concrete.ugh....

But mine is very streetable. As a matter of fact, anyone that can drive a stick shift car can drive mine without issue. The acceleration just get crazy especially when boost is above 20psi.

Tom

 

I see...

 

asa quicksilver mentioned, the "lag" is really a function of the rpm capabilities and power band of the engine at hand.

Switching to a properly designed tubular design would allow you drastically extend the powerband and useful rpms range of the motor (with the proper valvetrain, cams, intake manifold, etc). By extending the useful range, you'd eliminate the "sense" of lag.

For example going with a big, efficient tubular setup on a motor that is out of power by 7000 rpm is a waste of time! doing it on a motor that is capable of sustained 8000-9000 rpms would be beneficial. on a motor such as the latter, having a turbo setup that achieves full spool by 4500-5000 rpm is fine and not laggy is you have upwards of 9000 rpms to work with! as such, there aren't many VQs living up in those high rpms. they are out there, though.

the best example of what I am saying can be seen in the mid 80s formula one motors. these were smaller displacement, turbocharged V6 and V8s. this is a 2.6L Alfa V8, most likely spinning over 10,000 and boost limited by rules of the sanctioning body. Notice the roughly equal length exhaust runners, the double slip fit merge collectors, etc.



In such a situation where there are rules governing turbo sizing or boost pressure, you have to make a more efficient engine.....you can't just turn up more boost!!!

the ability to "add more boost" is why many people don't understand the advantages of a tubular design. if you can just "add more boost" to your current setup, why ditch the cast log?

well....more boost doesn't mean more power. you start reaching a point of diminishing returns, too much exhaust manifold pressure which, in turn causes an increase in pressure in the intake manifold (due to cam timing valve overlap!) so, the boost pressure you see in your gauge.......may also include exhaust gases that can't escape into the exhaust manifold due to too much exhaust manifold pressure. all that presure is also limiting your rpm range, too.

I hope this makes sense. I am trying to make this simple. there are many factors involved and it would take quite a while to fully go into it.

 

Great info.... That helps

 

So are you gonna talk to Sharif about getting some shorty tubes fabbed up Mike?

 

I will speak to him and see if he is willing to take that on after ZdayZ

 

I remember a few years back one of the shops on here made a twin turbo kit which placed the turbos up top towards the hood. I'll see if I can find that thread. They had some really nice pics, but the kit never went into production.

 

Thats the spirit!

 

+1

 

that was Mazoo from Intense Performance with twin GT37s

 

I happened upon this article the other day, and I think the way they are making these short cast tubular manifolds for this GT-R is awesome.

http://speedhunters.com/archive/2010...ification.aspx

 

wow that is sick.