tom94RX-7

iTrader: (5)

I'm wondering if the car will have any noticeable power increase if I switch from a rx7store resonated midpipe to a regular midpipe?

Anybody ever switch these two midpipes and feel a difference in top end power? I'm not really concerned if there is any low end power loss since I have the seq. twins and I'm looking for maximum peak hp with the seq. twins. I understand it would not be a huge difference, but anything little would be nice, and I understand the midpipe would be louder, I read lots of topics about midpipes but I'm trying to see if anyone has any first hand experience with both midpipes.

Let me know your thoughts. thanks.

drew32

I would also like to know if there is any difference.

BTW how long have you been running 19 PSI on stock seq. turbos?? How many miles are on them?

NissanConvert

iTrader: (1)

holy crap, how's your transition at 19#s?

Madee

iTrader: (3)

Those are amazing runs. Car really pulls off the line. You are hitting better times than lots of others with 100 more hp. Congratulations!

smoke wagon

iTrader: (4)

i also have a resonated midpipe and have been thinking about switching over to a strait through midpipe. i mainly wanted to make the exhaust louder, but would be interested to see if there might be any gain.

gracer7-rx7

iTrader: (16)

I've tried both with seq twins and felt no difference at all power/acceleration wise. The mid pipe was significantly louder and had a more annoying exhaust tone.

tom94RX-7

iTrader: (5)

I've been running 17+ psi for about a year and a half now. 106K miles.

Stock transmission has been good.

How about taking off the midpipe and just running the exhaust out of the downpipe, is that a bad idea or would that make it run faster? Of course I would just try it for running it like this at the track, like the hondas do.

Thank you.

2007 ZX-10R

it's possible Jason may have measured the pressure drop through the Magnaflow, but I'd wager it's less than 0.5 psi, since it's a straight through design

where I really noticed the difference was taking off my one year old SMB high flow cat, I immediately picked up about 1.5 psi, and most high flow cats are even worse, about 3 psi

2007 ZX-10R

on 93 pump gas??

2007 ZX-10R

that is going to be absolutely DEAFENING, even at the track

tom94RX-7

iTrader: (5)

Yes. 94 a year ago until they stopped selling 94 at the local Sunocos. I just recently got a water/meth inj. kit, but still ran 19-21psi without it (it peaks at 20-21 on real cold nights without turning up the boost controller, and the boost controller setting is not maxed out either).

tom94RX-7

iTrader: (5)

Ya I know the sound would suck, but if it can help me get a 10.9 that would be cool haha. I'm in the middle of upgrading the ignition too, 2 jacobs FC1000 amps and 2 C-4 coils for the leading plugs, was running 1 FC1000 and the old FC coil.

dgeesaman

iTrader: (7)

I have seen it done, but personally, no thanks. Even though the fuel lines run under the drivers' side, the idea of throwing flames at my gas tank doesn't appeal to me.

3GRX7

iTrader: (1)

what chance is there of blowing your engine running 19psi on the stock twins? Or are you just risking kiling the turbos?

Mahjik

iTrader: (1)

The risks are:

Charge temps
Fuel support
Ignition
Tuning


If you have those down, and it sounds this guy does, all you risk is burning out the turbos that much quicker. I would be interested to see a dyno comparing 16 or 17 PSI to 19 PSI. I'd be curious to see if the turbos are effective at that level and how much (if at all).

tom94RX-7

iTrader: (5)

I'm gonna go do some datalogging with my PLX wideband and g-sensor, i will report back with the g-senser readings of 16 psi compared to 19 psi.

2007 ZX-10R

+1

I think you at least need BNRs or you're way outside the efficiency range and just spinning the little suckers into the stratosphere at 19 psi

heck I'm only running by BNR Stage 2s at 15 psi

Rixio_Scon

What power did you make at 15psi on Bnr's? Im on Stage III's and im only making mid 300's at 15psi! Have you got a dyno sheet tom? Fantastic achievement btw In answer to your question i went from a RE-A res box to a decat and apart from a huge drone now on cruise there was a minor power increase and a low torque drop HTH

tom94RX-7

iTrader: (5)

See link below for my dyno sheet and time slip:

http://www.dragtimes.com/Mazda-RX-7-Timeslip-14792.html

tom94RX-7

iTrader: (5)

Well the g-sensor gave about the same reading between 15-18 psi during 2nd gear pulls, and also the same reading when I turned off the water/meth inj., but I it feels a little faster when running the higher boost numbers and a little faster without the water/meth (I add fuel to the inj map so it doesn't run lean without the meth.) 11.1 to 11.3 AFRs

FearNoPiston

iTrader: (17)

what size injectors are you running?

tom94RX-7

iTrader: (5)

Some new 850s and 1600s

skir2222

Hey whats up Tom? I love your setup, the numbers, and the times you put down on the 1/4 are fantastic. What you could try is getting a electric exhaust cut out(or manual) So with ease you can have a wide open downpipe. Your turbo's should defiantly spool much faster with much less back pressure from the exhaust. I don't know if you'd need a tune again though, that's what I would like to know. Your only reducing back pressure but running the same boost, so would you need to tune for that?

NissanConvert

iTrader: (1)

sequential *transition*

How is your transition at 19#s?

+1 for BNR's, your car is prepped for them and you'd probably get the numbers you're looking for.

tom94RX-7

iTrader: (5)

Sorry I must have thought I read transmission. The primary turbo maxes out at 13-14 psi, then it's a nice quick transition, jumps right up to the higher psi.

Someday the BNR stage 3s sequential would be nice, I have thought I may like going with them instead of a single turbo, but I've not driven a single turbo so I don't know. I've had bad coolant seals for a while (fixed twice temporarily with some Bars Leak stuff that works well to recondition the seals and keeps the coolant from leaking into the combustion chamber after shutting off the car), so I'm gonna need a rebuild before turbo upgrades.

Thanks for all the input about the exhausts.