insenothepunk

Yes I have searched. I'm just investigateing because I'm soon to start a rotary project in an FC. I like the twin seq setup but am wondering what is the max hp. I was thinking of upgrading to the BNR stage3's, and doing some searious work to the motor(cryo treatment, LARGE port, and all the other goodies). So if anyone could help me.

Mahjik

iTrader: (1)

Stock FD twins usually max out around 370-380rwhp (there are a few who have gone higher, but that's more in the minority than the majority).

BNR's haven't really been pushed yet, but they are seeing low 400's rwhp at the moment.

insenothepunk

Thanks, that's pretty much what I found. Little bit of details: I have a Ford Lightning to beat, and a buddy to prove wrong. The Lightning has about 60k invested in it and runs 12.6, and my buddy seems to think that I can't even break into the 12's with a rotory. So I'm gonna start my rotory project soon enough.

rynberg

Heh, you can run low 12s with full exhaust, intake, IC, PFC and drag radials at 13-14 psi or so.

NuTbAgSaN

well if his friend bought a ford he cant be too bright ahhh i gotta stop doing that im a former ford owner...u could spend maybe an 1/8 of what he did and beat his ***

fdeeznutz

60k invested and he only runs 12.6. I have seen a Lightning with a smaller pulley and slicks run 12.1. Thats with about $500.00 invested. I think your buddy is making **** up.

turbojeff

iTrader: (30)

I agree.

I've seen a Lightning running 12s/13s with just a pulley and K+N on street tires. I'm sure with slicks he could have cut off .2-.5 sec.

Snook

iTrader: (12)

yeah or you could run low 12s with intake, full exhaust, pettit ecu and 12psi with street tires : )

it doesn't take much...once you get the intake on there and the full free flowing exhaust the car goes wild....then turn up the boost some and you'll really feel the difference. The biggest mod for me was going to a midpipe from the stock cat and upping the boost 2psi. That day I must have picked up 35+rwhp or at least it felt like it. Trap changed from 106 to 112 after just that

I highly doubt you'll get 370rwhp out of the stock twins in any form. 340 is a tough but attainable number to aim for with higher boost. Sure people have gotten 370-380 or more but it doesn't work out for most people.

rajeevx7

iTrader: (11)

The question is a very good question and I have been inquiring about it since my first sequential problem back in 1999.

How much HP can sequential reliably hold? IE; not popping off a vac line every other boost!

SexyRx7 (?) Ashley has "365 WHP @ 17psi fully Sequential" but I am not sure how many vac lines she pops.
Who are the other big power brokers with full sequential? Remember....very reliable as in you beat on it at 14+ psi and nothing pops off!

Raj

z-beater

I agree with everyone else. Is he including the initial purchase of the car?

Turborx7s

Yes, it certainly is possible to get that much horsepower out of the stock twins, however, my bet is the twins don't last longer than 3000 miles. (If that)

In my experience, (and by this, I mean I did it) the stock twins are running dangerously too hard at 16+ PSI. The shafts are just too small, and long story short, they snap. Turbonetics used to do an upgrade where they would put larger wheels in, along with 4-6mm thicker shafts. Apparently, that didn't help because they also stopped doing it.

Bottom line, from my experience, if you want safe hp over the 350 line, go sinlge.
A t78 kit will make 350 at 8 psi with the base FD base PFC maps.

Of course, then you deal with some lag.

FLA94FD

I don't get how that could be possible. 8 psi is 8 psi right? I could see how the charge temp might be a little lower but from my experience that wouldn't account for that much. I dropped my charge temps 50-100C and while it allows for more aggresive tuning it isn't make that much more power by itself. I'm not saying your wrong just don't see how it could be possible.

Please help me understand.

wheezle

iTrader: (2)

You should pm rotarded. He was putting low 400's on twins (ported and polished) with stage three motor. His best 1/4 mile was 11.83 with drag radials. His boost was set at 15.4 lbs.

XxMerlinxX

iTrader: (2)

What about the BNR stage 3's or the Knightsport twins? They wouldn't be able to put out over 350rwhp safely?

Turborx7s

Yes, you are correct, 8psi is 8psi. However, really psi is just a measure of resistance, not actual airflow. (Pressure is a direct relation to resistance against an object) I don't know the "actual" numbers, (so nobody reply telling me im an idiot ) but I believe the stock twins max flow is something like 300 cfm. That, versus the T78 which flows something more like 750-800 cfm...(maybe?) Anyway, sorry I don't have the time this second to research exact numbers. The point is, that at pretty much any amount of pressure, the T78 just flows more air through the motor. Which, we all know equals more power. Also, at 8psi, the T78 hasn't even come close to reaching volumetirc efficiency. The turbo just isn't spinning nearly fast enough. So, while making that kind of power, your turbo is being kind of lazy. You are also correct in saying that the the charge temp is lower, do to this fact. Does this help?

CheesePowder

I'm not sure why but this doesn't make sense to me. If volume is the same (cuz the UIM+LIM and all the pipes aren't changing in volume). 8 psi is 8psi because it takes the same amount of air to create that much pressure as the engine is injesting it. So assuming both turbos can hold 8psi at any given rpm range, they will be compressing the same amount of air...and flowing the same amount (but they MUST hold the same pressure)

The point, I think (and tell me if i'm blowing steam) is that the flow rate of the turbos restricts them from being used at higher boost levels because they are no longer able to keep a consistent pressure level at higher rpms...because the engine is eating up the air too fast for them to be pumping it...This is seen in the boost pressures diminishing (trailing off when you go really high boost pressure and try to redline). A bigger turbo, which can flow more, will not have such a problem. However, I do believe that the stockers will do just the same in their intended boost range (10psi). As you start to push the turbos to a higher boost level (thus requiring them to flow more air) you reach that max line where they are no longer able to easily do it because of their size, and trim, etc. And that's when you go bigger or go single.

But if it's just 8psi, the air flow through the engine is the same...because the volume doesn't change. So having said all that, I think you are totally correct about why single turbos would be better but explained it all weird and confused the heck out of me...

Turborx7s

LOL...

FDreaming

You own a Ford... That's a Ford rear-end it came out of a ford plant, same with the tranny and alot of other parts. Why do you think FDs are so damn unreliable unless you do some anti-ford(the reliability) mods?

Snook

iTrader: (12)

I guess he read right over your post huh

8psi is not 8psi
well it is...all turbos wont make the same power at the same boost level

you think a T-88 and a 60-1 make the same at 18psi?

coblepots

8 psi isn't 8 psi in this case. the pressure measured here is gauge pressure which is minus atmospheric pressure AND any other pressures created in the system which would include the ability for the turbos to flow air. A more efficient turbo puts up less resistance and therefore reduces final pressure on the system. In other words, your engine doesn't see the same amount of boost say because 6 psi is lost by the turbo's inability to flow at that rate. Remember pressure is a measured difference when it's being read on your gauge, hence gauge pressure. Correct me if i'm wrong here.

Mr rx-7 tt

iTrader: (5)

#362 rwhp gets you into the 11's...

http://www.bridow.com/rx7/dragquick.html

11.42 @120.6

CheesePowder

Haha, thanks guys. I really was writing out of my ***. I get it now. I have to say that when you get laughed at by smarter people, it makes you a little bit smarter too.



Thanks for not flaming me too much. Hehe.

Turborx7s

Not at all...I think you pretty much just re-interated what I had said, but in a much more (and better) breakdown.

CheesePowder

oh okay. I forgot to mention the role of better turbo efficiency on charged air temperature. I think that's why SurgeMonster was ripping on me about the difference between those two turbos at 18 PSI.

Yeah, 18 PSI at 550 Rankine is MUUUCH different than 18 PSI at 700 Rankine!!

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Oh yeah, I guess 8PSI isn't 8PSI. Sorry about that.

Marshall

He's actually on the right track, but, in essence, you're both right. Most of the gains come from freeing up the exhaust path and lowering the IAT. Now you get the "dynamic" volume changes that make 8psi with one setup not 8 psi with another.