Braineack

iTrader: (62)

someone just build me this manifold:

Full_Tilt_Boogie

iTrader: (1)

done.



Should be easily modified to bolt up to a 1.8

apariah

What ?

JasonC SBB

apariah,

Pls. enlighten us why exhaust scavenging is the same between an NA car and a turbo car.

bbundy

With a turbo the exhaust resonance pre turbo has pretty much the same dynamic effects happening as a non turbo car that is a fact.

It is just turbo installation usually results in a crummy header design that has too short of runners. In college I built a long 4-2-1 header for a turbo SAE car and we saw huge gains in mid range torque and improved turbo spool.

Bob

JasonC SBB

Street turbos present a much higher backpressure to the exhaust valves than NA cars, especially at the top end. In my setup, the backpressure rises dramatically from 6000~7000 RPM. As such the dynamics of the scavenging will be different.

apariah

I'm not implying its the same, I'm thinking it probably just doesn't matter that much, especially on a "Turbo" Miata forum.

bbundy

It is still not steady state flow regardless of the added back pressure. The valves are driving a resonance by turning the flow on and off the turbo dose not negate that. There are still higher and lower pressure waves being reflected to the back of the exhaust valves.

Bob

JasonC SBB

The typical turbo setup has much shorter exhaust runners and thus the resonant frequency is much higher than a long turbo NA header. Perhaps so much so that it performs no useful scavenging from 4500~6500 RPM. How this interacts with the intake manifold resonance, I'm not clear on. I know the intake valve opening timing (and thus overlap), is a part of the scavenging, but how this affects the optimal intake manifold runner resonance, I'm not sure.

My main question is, has anyone seen positive gains from an intake manifold in an NA car?


apariah your douche post #323 doesn't add to the discussion.

Full_Tilt_Boogie

iTrader: (1)

Theres a reason for doing this:

TurboTim

iTrader: (9)

Add weight? Add failure points? Add resonance/harmonics? Add bling? Add lag? Add melted underhood components? Add hp?

Full_Tilt_Boogie

iTrader: (1)

All of the above

redrider706

iTrader: (4)

Do you guys think placing the injectors in the plenum aiming at the runner opening would increase power? A lot of motorcycles have started moving the injector away from the intake port. In the Ducati superbikes they are actually placed in the airbox aimed at the runner opening. I talked about the effect of such a setup to a superbike crew chief and he said that they saw a significant increase in power the further they moved the injector from the intake ports. But, most bike do have a straight runner to the intake ports.

Savington

iTrader: (31)

Yes. Emilio saw huge gains in his '99 Frankenstein motor switching from a USDM 01+ manifold to an EUDM "Squaretop" manifold. I don't recall exactly how much, but it was a bunch, like 15whp.

And before you all go looking for one, don't bother. They are impossible to find.

JasonC SBB

Hmm why did he start with the VTCS mani instead of the VICS mani?

Savington

iTrader: (31)

It could have been a '99 manifold, I don't recall off the top of my head. Either way there were huge gains going to a EUDM/JDM squaretop.

We will do a back-to-back with my Honda manifold vs. the 01+ VCTS manifold on our '90 rental but not anytime soon.

bbundy

My Turbo manifold has equal length runners about the same length as the stock NA tubular manifold.

Go look at some WRC turbo setups, cars designed for lots of mid range torque and throttle response while running relatively large free flowing turbos. The turbo will be mounted at the end of a relatively long header.

It is not that the scavanging with a turbo dosn't work its just that it is ignored in most cases to make it easy to mount the turbo.

Bob

emilio700

iTrader: (3)

Doesn't matter, they're both turds. The square top, while still not ideal, is a vast improvement over any variation of USDM manifolds. That includes hogged out and ported USDM manifolds. The best performing 1.8 N/A manifold I've witnessed is an aftermarket Honda manifold grafted onto a BP4W manifold flange. Big gains everywhere. As my welder, who is otherwise blessed with angel like steel welding skilz, gave up on trying to successfully put together the Skunk2 B18 manifold and BP4W flange I gave him, I done gived up. For now the daily driver gets a square top until we get the 949 Racing intake manfold into production next year.

No, I won't share pics or info on ours

TurboTim

iTrader: (9)

I'll guess it's a dual plenum jobbie.

shifty35

Staged injection isn't a bad idea. The upstream injectors are way to slow for idle / low rpm, so you'd want to use the stock injectors for idle / low rpm, and switch completely to the upstream injectors at some point.

It's good for some solid gains in N/A applications, not sure it's worth the hassle in FI.

Having come from the Honda community, it's good to see people taking advantage of the retarded surplus of cheap, well designed parts.

For the 1.6L solution, someone should compare a Honda D series intake manifold. They have closer port spacing than the B series manifolds, and you can still find Blox / Skunk 2 copies easily.