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93 maybe 94 coupe
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289 Posts
Discussion Starter #1
Given that the flow velocity requirement of a swirl port head generally dictates a smaller, longer im runner for a given power level, is it safe to assume that a tumble style design would be better suited to high rpm use? I notice a massive plenum volume on a y8 im but ppl say it's chamber is similar to the y7. Is this ABSOLUTELY correct?

Ppl also say any im is better than a y7, but in its application isn't it ideal? I think putting a fat im on that motor may be mismatching parts and I've already done that to the extent I was disappointed so I'm tryna fully understand what's up.

Right now I'm half looking for a vtec head to drop the y7 gear into but I am unsure which head will suit my plan the best. (A slightly tweaked beast7 built to run towards the upper end of the head/cam combo's rpm range)

What do u guys think?
 

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Brokedick Millionaire
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40,267 Posts
Y7 has a Z6 size chamber.

Think about valve size, valve location, HG thickness, etc.

Y8 IM kills a little midrange TQ for top end gains, I'll take the midrange please, why I went back to Z6 and ported Z6 IM on my Beast7.
 

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94 Integra
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Adding plenum size quickly shows diminishing results. However some plenum space is better than almost none, and the y7 IM has almost none. The z6 is easy to find & quite cheap. It will accept an OBD1 iacv & iat readily, and is easy to connect to any fuel system. The y7 and y8 IM's are a pain to adapt to an ODB1 iacv & iat. The y8 is much more expensive than the z6 because people think it dumps unicorn piss into your engine.

Regardless of how the z6 & y8 compare, both are FAR better than the y7. Same goes for most aftermarket IM's, they are MUCH better than both z6 & y8. One guy on the DSO FB tested ~410whp with a z6 IM then ~440whp after ONLY swapping to a Skunk2. 30whp is great, but look closer: 400+ from a z6...
 

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93 maybe 94 coupe
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289 Posts
Discussion Starter #4 (Edited)
I was really looking forward to flat tops and the y7 chamber, my old camaro was fun to tune when I went from standard to fast burn heads so I'm assuming the deviations from a p06 stock tune will be similar.

It looks like it may be raining unicorn piss though, I'm pulling a running y8 Sunday for a dude going b series, and getting the complete engine for 80$.

It's an automatic car, but I can at least use the head and sell off what isn't good to keep around. And soon enough I'll be able to actually check out the chamber design physically in person. I've never had so many random Honda parts around so this is pretty cool.
 

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D-series Janitor
Front Engine Dragste
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1,220 Posts
Ppl also say any im is better than a y7, but in its application isn't it ideal? I think putting a fat im on that motor may be mismatching parts and I've already done that to the extent I was disappointed so I'm tryna fully understand what's up.
I think in the specific application of a grocery getter 4cyl with an automatic, the y7 intake is fine. The velocity through each runner i'm sure is higher than a z6 or y8 up to a point, at which the turn and small size obviously choke it off.

I would imagine a y7 intake would make more torque under a given RPM, 2500? 3000?
 

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5,879 Posts
y7 manifold is porbably the best under 2500rpm

but a d15b7 intake manifold would maintain a strong lower midrange, and not completely eat shit if revved up to 5-6k

a ported z6 intake manifold where it was cut open and bell mouthed would be one of the best all around performers
 

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93 maybe 94 coupe
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289 Posts
Discussion Starter #8
Well a z6 manifold is designed for a tumble port style head. Where all this is going (once I check out the parts in detail) is a discussion on quench, and the merits of swirl vs tumble.

As for "specific application" I was referring to the head design rather than intended use of the vehicle.

I figured a b7 intake would be a decent all arounder on a y7, but I'm not sure if losing velocity is in the best interests of the head.

On a z6 head it seems that bigger is more or less better, and this might help explain why ppl don't dig the peakiness of a y8 manifold on the z6 and a6 heads... Does anyone have experience running z6 vs y8 im on a y7 head? Maybe the peakiness is in the design.
 

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the d16y7 would benefit from a b7 or z6 manifold far more than you believe

its the d16y8 intake manifold you want to avoid putting onto the d16y7. its reduced my gas mileage and killed off all my power until high rpms, which I cannot use anyways since the transmission shifts under 5k rpms
 

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93 maybe 94 coupe
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Discussion Starter #10
Is that how a stock y8 feels? If not I'm guessing I'm going to find some significant differences between the chamber designs, which will give me more ammo for questions regarding the matter.

In the end I hope to better understand the quench characteristics of the various piston/chamber combos one would generally piece together for a beast7 inspired build.

My initial y7 head plan still seems to have its advantages over milling + cam and pulley
 

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\/Your Mom Was Here\/
Vibe GT
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You can take any head you want to use, even an old A6 head with the nice valve spacing that these engines should have and then have the quench pads welded up by a really good aluminum welder and get it milled by a machine shop.
 

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93 maybe 94 coupe
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Discussion Starter #13
That's beyond me but I'm starting welding at a tech school soon, looking forward to the opportunities knowing that trade inside and out will bring. Sorry for so many posts I had a lot of spare time to think about stuff today
 

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93 maybe 94 coupe
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Discussion Starter #14
Ok so for 80 bucks I pulled the y8, so I now have a spare y7 and y8. (And two unwanted auto trannys taking up space) If I plan on going forced induction beyond my current beast7 aspirations, how would I go about dealing with the oil jet swapping other parts around?

If if I put the head off the d15 on one of the 1.6l motors to lower CR for boost, is the oil jet that must be pulled from my d15 an issue?
 
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