Would port matching my Skunk2 to FlatTop lose power?
#22
We're all talking about theory. No one has yet to post up A/B testing showing said dramatic power losses. I'm guessing 1-2hp, but if I'm wrong then we'll port that sucker asap
*edit: I'm also pretty sure there's a step from the IM to the head, those are not perfectly port matched either.
We can re-dyno tonight if you want and see if it really did lose power
*edit: I'm also pretty sure there's a step from the IM to the head, those are not perfectly port matched either.
We can re-dyno tonight if you want and see if it really did lose power
#23
The step is not helping flow. Perhaps on a NA miata, the air speed through that spot is low enough that the actual reduction in flow is small (trivial, 1hp, whatever) but it's there. As mentioned a 30* change in temps is probably the main difference in your dyno numbers, but I'd still port match it.
#26
The step is not helping flow. Perhaps on a NA miata, the air speed through that spot is low enough that the actual reduction in flow is small (trivial, 1hp, whatever) but it's there. As mentioned a 30* change in temps is probably the main difference in your dyno numbers, but I'd still port match it.
but I'm completely open to being proven wrong. I'll admit I don't know much about porting/polishing and intake resonance and all that voodoo
LET'S DO IT
#28
Are you trying to imply it is still a guesstimate vs you showing us dynojet plots which are usually within a couple hp?
Please
*edit: No one is arguing that this is better than a real dyno. But to call it a guesstimate is dumb in this case cause of the way we're doing this. One could even make the argument that the VD output is more realistic than a dynojet because the car is actually loaded up on the street like it is naturally, vs just spinning a drum. No offense.
#30
The point of a dyno is consistency, not realism. Nobody is going to argue your point because it's not relevant to the discussion. If you're not taking VD pulls in a controlled space, then no, it isn't consistent. As to how much variation in wind/temperature/etc is OK before it starts affecting results in a noticeable way is not something I can comment on.
#31
The last part was just an observation, not an argument, hence my comment as well as disclaimer.
I'm not getting into a peeing contest over dyno's, It's pointless. OP can throw the car on any dyno he wants, I can even arrange a trip to the local mustang dyno if he wants.
I just don't appreciate the guesstimate comment is all.
#32
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A dyno is a friggen tool. It shows you gains. Just like virtual dyno shows you gains. When you do a baseline pull, and then repeat it minutes later on the same road in exactly the same circumstances (we literally used a marker to start/stop pulls, doing them in the identical fashion every single time).
Are you trying to imply it is still a guesstimate vs you showing us dynojet plots which are usually within a couple hp?
Are you trying to imply it is still a guesstimate vs you showing us dynojet plots which are usually within a couple hp?
*edit: No one is arguing that this is better than a real dyno. But to call it a guesstimate is dumb in this case cause of the way we're doing this. One could even make the argument that the VD output is more realistic than a dynojet because the car is actually loaded up on the street like it is naturally, vs just spinning a drum. No offense.
#34
Until it's capable of compensating for simple things like ambient temperature changes, in my opinion, it's a guesstimate. If you want to use it for direct A-B changes within minutes with calm winds on the same road on the same day, that's fine, but that's clearly not how it's being used.
And that's exactly how it's being used, I keep saying that and people keep ignoring the posts that clearly say that.
Anyways, I'll just post up a proper comparison with all the data and we can all see if power was lost or gained and go from there.
I'm just as curious as everyone else regarding what power is gained or lost here.
#35
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I'm sure VD can be used to obtain solid A-B data, but this entire thread is predicated on 100% bullshit data. That's where my "guesstimate" comment comes in, because if you're taking datalogs from different days and expecting it to be considered as "A-B testing", then "guesstimate" is about as nice a word as I can come up with to describe it.
#36
We never performed controlled A/B test with matched vs unmatched squaretops & Skunk2 TB. I feel pretty confident that the step that exists hurts power though. Our standard recommendation for adding a Skunk2 to eliminate shaft breakage without gaining significant power is based on A/B from OEM to Skunk2 on an unmatched VICS manifold.
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#38
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I also port-matched my Squaretop to the Skunk TB...
https://www.miataturbo.net/build-thr...-62620/page24/
I recommend replacing the idle set screw and the screw that it stops against. They break and come loose.
https://www.miataturbo.net/build-thr...-62620/page24/
I recommend replacing the idle set screw and the screw that it stops against. They break and come loose.
Last edited by 99mx5; 02-18-2016 at 02:59 AM.