theory

iTrader: (5)

Just like the title says, has anyone lost power/tq by doing the S5 intake swap with functioning vdi?

I went to the dyno the other day and made 155rwhp and 131 rwtq with my S4 manifold. I have an S5 intake here I'm building up, but I just want to check if anyone has lost power with this swap?

I'm also trying to figure out how the S5 will affect my TQ curve.

RotaryRocket88

iTrader: (7)

Slight increase in torque from around 4k-5k, but most of the power gain is from 6k-7k, since the VDI is only activated above 5.2k. This is all according to silver88gxl's posted dyno comparison. I'll post the dyno pic later; it's on my other comp.

I swapped manifolds on my NA motor, and it was a noticeable gain with the butt dyno. You have to redline a lot to feel it, since there's little change under 6k.

RotaryRocket88

iTrader: (7)

Swap writeup & dyno:
http://howto.globalvicinity.com/gv_w...i=63&co=1&vi=1

theory

iTrader: (5)

Well I guess that answers my question.

Thank you for posting that.

Rx7TyreBurna

iTrader: (1)

I noticed a bit more pull after about 5.5k-6k.

If you are staying N/A and you have an S4, it is really worth it IMO. I kept the S4 LIM though. So, that made it slightly more difficult. But, some say, it flows better or something. LoL. For me, it was just cheaper.

RotaryRocket88

iTrader: (7)

Keeping the S4 LIM also lets you pass smog. The exhaust passages won't line up if you use a S5 LIM on a S4 block.

Templeton

iTrader: (10)

i knoticed a decrease but that was without functioning vdi, if i wired it shut i didnt really gain low end and i lost top end, and when open i lost low end but gained top. i wouldnt suggest it unless you plan on setting up an rpm switched actuator for the vdi. that said im back to my s4 manifold.

Rx7TyreBurna

iTrader: (1)

OP posted with functioning VDI.

So, switch. you get the good part of each. You won't gain low end, but you will gain high end.

Wiring it open does kill low end, same with wiring it shut, you don't gain anything. But with it functioning, you just get an extra kick at 5.5.

Summit RPM switch is a good deal. Used with an F150 Lumbar pump.

theory

iTrader: (5)

Update:

Dyno results before swap:

155 rwhp
130 rwtq

Dyno results after swap:

158 rwhp
126 rwtq

Fully functional 6pi (opens at 4000) and fully functional VDI (opens at 5000)

Only thing I can think of which would explain the lack of higher numbers is tuning.

Not really what I wanted for all the work, but I think after some tuning I can get the numbers up to what I want ( 160-170 rwhp, 135-140 rwtq)

Black91n/a

If the runs were done on different days, and especially if different dynos were used, you can't do a direct comparison, the variables can easily make the difference and make it seem worse, when it's actually better.

theory

iTrader: (5)

Although done on different days, it was done on the same dyno by the same person in the same shop.

I'm not super upset, it's the name of the game. I'll do some tuning, and get more results from the same dyno to compare.

I will say that it was 10 degrees F cooler this run with the S5 swap, and there was 16% less humidity (27% humidity last time vs 11% this time, just reading from my dyno sheets)

Icemark

3800-3850 is better for opening the aux ports (since 2ndary injectors open at 3800) and VDI should be fully open at 5200.

Been my experience that unless you use the S4 LIM on the S5 VDI swap, the S5/VDI swap does loose a little torque across the board starting at around 3600.

theory

iTrader: (5)

I'll try opening them a bit sooner and see what that does.

details of swap:

S5 Dynamic chamber and UIM, S4 LIM, gasket matched all the manifolds, RTek controls 6pi and RPM switch controls VDI. All emissions kept except EGR.

Rx7TyreBurna

iTrader: (1)

Hmmm, this ever get better?

I was thinking, for VDI to be effective, you would need good compression right? Higher compression would cause stronger pressure waves right?

walken

iTrader: (6)

still amazing numbers for a n/a. your dyno in my mind proves the biggest increase was the compression ratio on the rotors.

theory

iTrader: (5)

I did open the aux. ports earlier, but I haven't back to the dyno yet. Once my job gets back to 5 days a week I'll head back and see what I can hit.

Those results were on 2 completely different days in the season which could make a big difference on the numbers. We'll see what it pulls this year.