Does any one make tubular turbo manifolds for the VQ engines?? All the ones I have seen have been cast logs. I didn't know if this was because the lack of space, or if it can even be done custom.

 

Speed force racing does and I think JTran studios might. Some opinions are the tubular manis will sag under high heat if you track the car but I haven't seen proof of this theory.

 

Thanks for the info. Yeah that theory about them sagging seems a little far fetched to me. I have a full-race turbo manifold on my Acura and dailyed and tracked. I saw better gains in upper hp when i just switched out the cast log to to tubular mani. I just wondered if this held true on the VQ platform.

 

The guy I have seen use them the most are the BIG horse power guys that are running twin GT35s.

 

Yeah I ran about 492whp and didn't have a problem, this was on a fully built and sleeved block. I was also thinking about the JWT set up and going for bigger turbos, maybe along the lines of a pair of GTX3071R's or GTX3072R's if JWT could get them and swap them on since they are in the same GT30 frames. I go big so I don't have to go home on my builds and I pretty much do all my work myself( except machine) hell that is was I went to school for.

 

Speed Force Racing and Sound Performance Racing both make tubular manifolds. I also have heard about tubular manifolds sagging.

Also, with log style manifolds, the turbines are closer to the exhaust ports. I have heard it said that this helps spoolup because the exhaust gases are a little hotter, though there will be more backpressure. Nonetheless, unless you are going for over 1000 whp, I am not sure the backpressure is a big concern for log style manifolds. XKR made 1000 whp on a dynojet (north of 800 on a DD) with log style manifolds, and his torque curve looked really good. Below is his DD dyno plot. This was on a 4.0L stroker motor with GT 3582R turbos.



Perhaps ceramic coating the tubular manifolds will help. Anyway, take a look at dyno plots for the various turbo kits before deciding.

 

Well I don't think that it being close to the exhaust ports helps. I know they the log styles are cheaper and more durable. The tubular manifold even out the exhaust pulses so they are fighting each other and building up. This causes a steady pulse of gas spinning the turbine in a timed order much like the engine firing order, and the longer runners allow for more thermal expansion of the gases therefore increasing the velocity at which it strikes the wheel. Both I believe make the system more thermal efficient in using a higher percent of the exhaust energy. Now this is j

 

Now this is just my opinion and experience.

 

Some type-o..."arent fighting"

 

A turbo operates based on the pressure differential across the turbine. As the exhaust gases expand in the exhaust manifolds, there is less pressure on the turbine inducer, and thus less pressure differential across the turbine. Accordingly, less energy is driving the turbine. Remember, the Ideal Gas Law states:

pV=nRT

where p is the absolute pressure of the gas, V is the volume, n is the number of molecules, R is the universal gas constant, and T is temperature.

 

your 4cyl built sleeved block @ 492hp, most VQ's will run 450hp all day long on a stock block with a basic cast manifold (like me) Greddy 4 Life

 

I knew Terry would be in with formulas another thing inline engines you can pair your cylinders via the tubular manifolds to decrease spool time but V engines with twins it is not possible so the benefits may not be as substantial as an inline with tubular manifolds.

 

Ok The Ideal gas law is when you add Avogadro's law to the combined gas law, your equation is only good if you have an ideal gas, meaning like a pure noble gas, and not a mixture of gases (real gas) and use van der Waals equation. The Ideal gas law also states that there other consequences to take into consideration, such as if the temperature changes and the number of gas molecules are kept at a constant, then either pressure and/or volume will change in direct proportion to the temperature. So if the temp goes up then the pressure and volume will increase too. You also have to take into consideration that the exhaust system is some what of a contanier and that gases act under pressure and heat a certain way.

PV= kNT

And yes I know that there is a pressure diffierentail
And to Mr. 4 cylinder hater, I took an engine that made 180 hp @ the crank and made it turn over 400 hp to the wheels on medium-high boost, so if you take into effect what was lost in the drivetrain. and you are saying that a VQ will do 450 all day like what the 4 did is nothing then you need a reality check. Im not knocking my VQ I love it I just hate when ppl talk to about every other thing there is other than their car. I built that engine with my own two hands and plan on doing the same to my VQ.

 

Charles mentioned that full race was working on a set for his 370, so they should be able to swap to the 350... Like others said SFR and Sound Performance make tubular manifold, but they place the turbo down low near the transmission.

 

Still, using pV = kNT,

p = kNT/V;

Hence, as the volume increases, the pressure decreases. Moreover, the more surface area there is on the exhaust manifolds, the more energy is being dissipated before the exhaust gases reach the turbos. In other words, the termperature of the exhaust gases will drop a little, which also will drop the pressure differential accross the turbine.

From what I have seen on our platform, the log style manifolds seem to provide faster spoolup than tubular manifolds. The tubular manifolds should provide a bit better high rpm performance because there will be less back pressure, hence the engine will breath better.

If you search the my350Z site, str8dum1 plotted his dyno chart and and others for comparison purposes. str8dum1 has tubular manifolds. He has very high top end power, but does not fully spool up until beyond the 5k rpm range.

Edit: here is Str8dum1's dyno plot:



Str8dum1 is using 6262 turbos, which I think are similar in size to the Garret GT3582R turbos. In comparison to XKR's build, Str8dum1 used a 3.5L motor. So the displacement is about 12.5% less. This also will affect spoolup.

If I were to use tubular manifolds, I would definitely ceramic coat them to minimize the loss of thermal energy.