Well, I know of as many rx7's that made 400rw in the stock twins

and the engines are extremely short lived....that level of power on the stock twins is temporary at best

 

Plenty? Come on. We both know that most FDs with stock twins will never break 350 RWHP, let alone 380. With race gas and 17 psi, for SHORT PERIODS OF TIME, sure, you could make 380 RWHP with all the right parts and lots of tuning, but that doesn't make it the norm or common.

I listed ~440 RWHP as fairly common and very acheivable for a BPU Supra on pump gas. For the FD, the equivalent would be about 330 RWHP.

 

You can say that again.

 

EDIT: Darn...FD from R1 beat me to it

17psi is good for what...10 runs? lol. I thought the stock twins are already out of their efficiency range at 15psi, and so at 17, they're spinning so fast, failure is inevitable...

Don't get me wrong, the #s Rich made on the BNRs def. look VERY promising. I said that before, and I'm saying it again. And it's even more encouraging that he informed us Bryan thinks these turbos are good for 20psi...(which I assume means consistantly running 20psi....). Obviously, that would be the first, easiest and best solution to make serious power on twins...BUT, I have yet to hear of anything saying that Bryan is offering these twins in sequential as well...

Do me a favor Stephen, and find out if they're only in parallel or not...because simply said, if they're only parallel, the supra twins seem like the ONLY other option for large hp #s on sequential twins...unless someone can point me in another direction...

EDIT: While your math and logic prob holds true (I don't know enoguh to verify lol), what you're missing is that you're comparing stock to stock. The stock 2JZ to the stock 13B-REW. Yess, there's definitely less air. BUT, who's gonna be trying to make 400+ hp on a stock engine?? I wouldn't. If you get a large aggressive port, now the engine can flow much more than stock, and you can bring it to the point where it can match - or even beat - the air moved by the stock 2JZ. Then, all you gotta worry about is loss at the flywheel (which is kind of inevitable).

 

Actually, I never had a problem with intake heat from mine. The reason is I had a good IC with low pressure drop. The more pressure drop you have the harder your turbos are working. Running 17psi with a low pressure drop IC is getting close to the eff limit before they start to heat the air. If you have a lot of pressure drop you'll never make the higher power. The twins are good for a pretty reliable 380rwhp if the car is setup and running right. I'll admit however that its rare to find a FD where someone really had it running right.....but that has nothing to do with the turbos.

In addition the issues like a lot of tuning, ect being needed would be the case even if you were using Supra twins.

I'm not saying the Supra has bad twins, I'm just saying I dont see that its worth the expense to try and convert thier entire system over to a FD. But hey, if someone wants to give it a shot then stop talking and start fabbing. If you make more than 400rwhp on pump gas I'll be the first to congradulate you. Really though for it to be worth while they probably need to be capable of 425 rwhp on a rotary with pump gas considering you can break 400rw with $2000 upgraded twins on pump gas.

 

Stephen, I see your point...but re-read my previous post (I edited it).

Also, what ICs have large and small pressure drops? How would I find that out? And how's Chuck's V-Mount fare?

 

You're forgetting that the Supra twins use a slightly different method of sequential control. The easiest and only feasible way to use them would be in parallel configuration.

Actually, I think Stephen was using BSFC (brake specific fuel consumption) for his comparison, and he's right that the rotary has a lower BSFC than a piston engine, but BSFC is based on fuel consumption... not air consumption. He also failed to consider that the 2JZ-GTE is a 3.0 liter engine and the 13B-REW is only 2.6 liters when compared using the same rating method as a piston engine.

Stephen, sometimes I think you know just enough to hurt yourself. You are generally one of the more knowledgeable people on the forum when it comes to the car, but when you start quoting figures and spouting theory, I just shake my head. However, I apologize for being so condescending about your blind spot.

 

Well, at least we agree on something.

 

Your never going to get it to that point. The numbers I mentioned in reality would be with a street port. The best way to see what I'm talking about is look at dyno numbers for a certain single turbo street ported FD then find numbers on other piston engine cars with the same turbo at the same boost and you'll see what I'm talking about.

 

Either way, if you compare what a rotary makes with a given turbo at a given boost its always 10-20% less than a piston engine.....just depending on what piston engine your comparing it to

 

what's really amazing are these dyno queen Supras laying down 800+ at the wheels....just incredible

 

I think you're missing the point. You can't make a direct comparison, just like you can't simply assume that a 20B at the same boost level will automatically make 50% more power. Engines are a little more complex than 10% this and 20% that.

 

Everyone knows that the rotary makes less power than a piston engine given the same turbo and boost, even some smaller piston engines (take a Honda engine for example) with the same turbo and boost makes more power than a 13B, I'm not exactly sure why other than just poor combustion eff on the rotaries part due to the oblong chamber shape. Anyway, I never said it was exactly 10%....I said its at least 10% and that it just depends on the efficiency of the piston engine your comparing with. I've never seen a rotary come within 10% of a piston engine with the same turbo and boost. That doesnt even take into account that with every breath the 3.0L takes in more air than a 13B, just from that alone your going to need to run more boost than a Supra to get the same cfm out of the turbos.

There isnt much use in debating about it, I'm not that worried about it. The ONLY way to TRUELY know what will happen is for someone to do it and I suspect thats not going to happen so all this debate is worthless anyway. If anyone wants to try it then my position/opinion is there is no way in hell your going to make the same power with those twins as a Supra does and boost for boost I dont even think you'll make more than the upgraded BNR twins. But if anyone wants to try it be my guest, I'd be very interested in the outcome

Jim - it seems like we always agree with half and disagree with the other half....maybe one of these days we'll land on the same page hahaha. At least it keeps things interesting and fun

Later guys,
STEPHEN

 

Well, I'm just going to have to revise my conversion list...

1 centimeter = 0.0328084 feet
1 cubic centimeter = 0.001 liter
1 kilogram = 2.2046226 pound
1 horsepower = 0.7456999 kilowatt
1 foot pound = 1.36 Newton Meters
1 20B = 1.5 13B-REW
1 13B-REW = 0.8 2JZ-GTE
...

 

No I had that in mind. But I'm wondering if it's possible to run the supra twins, using the RX7 equipment (actuators, etc), thereby making them run sequentially just like ours...

OR

From what I understand the Supra's sequential control is a bit simpler than ours, in which case, with a lot of time, I think it's very possible (just incredibly time-consuming) to correctly program an ECU to control them in such a manner... no?

I know it seems like I'm beating my head against a brick wall, but I'm just not willing to accept that you HAVE to ditch the sequentials...

I was reading a while back about the Porsche 959...which also used sequential twins. Get this: "The stock 959 made 450 hp at 6500 rpm and 380 lb-ft at 5500 rpm. Full boost of 1.4 bar occurs at just 1500 rpm."

Keep in mind the 959 was 2.85 liter flat six. The turbos weren't in line like ours or the Supras - they were far from each other, with a long line that took air from one side to the other when only one turbo was working. Then, when rpm threshold was hit (at 1500rpm!!), the engine ran the two turbos in parallel, each one feeding off one side of the engine.

Now c'mon...you're telling me w/ 1980s technology like THAT, we can't run 450hp on sequential twins on an RX7 in 2004???

 

I admire your tenacity, but the irrationality evident in your single-minded focus on reinventing the stock sequential turbo system is starting to become extremely annoying.

 

Sorry Jim, but something upstairs is bothing me, considering the car's been out for more than a decade, and nothing better than the 99 twins & BNRs was ever developed...it's like there's a loose end/unfinished work IMO.

Lemme ask you this then...(not giving in, just keeping an open mind LOL), what would be the pros of going parallel? (over sequential, performance-wise...)

Oh and I know there are parallel twins that can definitely handle 500hp (like the Apexi/Border twins), but from what I understand, the lag on them is HUGE... when do the new BNRs develop full boost by?

 

Why does it matter if the FD receives the same exact HP #'s as the Supra? Did we not forget the weight advantage that becomes a bigger margin as you ad to it? Am I right?

 

There's a packaging issue. When's the last time you took a look under the hood of an FD?

 

Are you referring to lack of space, or was that your way of taking a low blow at the rotary (again)? LOL

 

Lack of space. Do you even own an FD?

 

No of course I don't. I'm just speaking all on hypotheticals, so that I'm ready that one day when I DO buy an FD...

Ok, space is tight, but aren't the Supra twins SMALLER than ours? Plus, the Apexi/Border twins run parallel fit in the FD, and are capable of flowing 500hp, but they're in parallel. So from MY understanding (as limited as it is), it seems that space isn't the real issue, because there are turbos that are the same size (and even slightly smaller) that can flow that well.

Apparently, I'm wrong, because that's where you seem to be leading me lol. But again, some ppl are fitting T-25s and T-28s under there, which are *considerably* larger than stock, aren't they? (Aren't stock T-12s??)

 

You're wasting everyone's time with hypothetical conversations about modifications for a car you may eventually buy and you're rolling your eyes??

 

LOL Jim, I was being SARCASTIC. Hence the rolling of the eyes... OMG lol

EDIT: JUST IN CASE it wasn't clear, I own a 1994 R2, black on black, 83K, w/ all the bolt-ons. I've had her for 2 years now...

 

"nothing better than the 99 twins & BNRs was ever developed"

really? might want to take a look at the japanese aftermarket - several companies offering twin set-ups (essentially rebuilds) over 400hp (conservatively dynoed). Info and images re: the knight sports 420 (hp) set were recently posted on here (garage alex have a similarly-powered set out as well - and they're significantly cheaper)