No, I think Stephen is off his ******* nut. There's a difference.

The stock fuel system has been proven to be good for about 500 RWHP. Chris was running C16, though.

Hard to say, but I'd be surprised if you couldn't break 400 RWHP on pump gas with proper tuning.

And an HKS VPC, which allows primitive fuel adjustment. Actually, IIRC, Chris was pushing 24-25 psi before he went to a single turbo. I was running 1.3-1.4 Bar (19-20 psi) on the street in my Supra, on pump gas, on a daily basis.

 

It seems to me that if Jim's info is true (efficient at 18 psi and possibly higher) that a MODDED FD would take a set of Supra twins quite well. I wasn't thinking of swapping twins on a car with no ECU or fuel upgrades. If one were to have the fuel to support say 18 psi, why would you not want to keep the sequential setup, get small single power, and not have to worry about your stock twins taking a crap?

18 psi on stock FD twins vs. 18 psi on Supra twins would certainly be more than a few horsepower difference, right?

Ever learning...

Alan

 

If there were a ready-made exhaust manifold that made it possible, that would be one thing. As it is, adapting another car's sequential system to the FD is more trouble than it's worth. It would be easier to build (as someone is doing in another thread) a parallel twin setup, or just go single.

 

C16?? Ahhh...but doesn't that inflate your hp #s incredibly? Eg. the guy w/ the 3-rotor RX8 and a huge single @ Rotorfest was saying how he made 600some hp on pump gas, and 900+ hp on race gas... (I think it's AcostiaRacing or something like that on the fourm). Cuz if so, I'm thinking his 485rwhp on C16 would be something like 485 flywheel on pump?

I have heard and understand that the stock fuel system on the Supra is good for 500rwhp, but based on that, can you follow that the Supra is capable of 500rwhp on the stock twins and engine, on pump gas?

Just how much psi can these twins hold?? You're talking about 19-20psi on pump...#s we can't even touch on the stockers or even the '99s (Rich, THAT'S why I'm interested in 'em...).

Alan, I'm w/ you 100%. I'm thinking an FD w/ all the bolt-ons, PFC tuned well, WI (just in case lol), aggressively ported engine, maybe some 1600cc secondaries, supra fuel pump...ignition amp, etc...you could do some serious damage w/ those twins.

~Ramy

EDIT: Jim, I totally understand your point, but at least for me, it's not about how much trouble or how easy it is. It's about having the best of both worlds IMO. If it can be done, and the results are as promising as they seem, I think it's VERY well worth it to ME.

 

I heard that these twins were extremely heavy. I saw a pic a while ago and they were massive(end to end). Anyone think there is enough room in the engine bay to fit these?

 

I dunno...you tell me....

 

C16 doesn't make power by itself. The higher octane helps prevent detonation while you make that power. The point is that he made 485 RWHP with stock twins and has a dyno chart and time slips to prove it. The debate was about what the MKIV stock twins were capable of, and I posted numbers for both pump gas and race gas. I didn't see anyone set a limitation of pump gas only.

No, like I said, there are many BPU MKIV Supras making ~430 RWHP on pump gas. C16 isn't magic pixie dust or Rikki's secret sauce. It allowed him to safely run more boost, certainly, but it didn't create the extra 55 RWHP by itself.

No. 430-440 RWHP is about the limit on pump gas with the stock twins. Chris is the highest RWHP on stock twins that I've ever heard of, with race gas. The 500 RWHP limit was discovered by people running small single turbos with the stock fuel system.

Chris was running 24-25 psi on race gas before he went to a single turbo, and I know for a fact that they'll easily hold 20 psi to redline, because that's what I ran for the 3 years I used the Supra for my daily driver. BTW, at the end of that 3 years, my compression numbers were incredibly strong and within 2% from cylinder to cylinder.

I didn't say "it's more work than it's worth" for nothing. You'd spend less and have less headaches going with a small single turbo, and probably get about the same results.

 

What size turbo would you recommend to keep low end power. I'm not a big hp kinda guy. I like the driveability of the sequentials. But also like the idea of cleaning up all those vacume lines from the UIM, emptying the engine bay a little and maybe saving a little weight/heat too. What all would you have to get to run say ... 14psi on a smaller single turbo?

 

I'm not arguing w/ you Jim, but I while I understand higher octane gas helps prevent detonation, I was under the distinct impression that higher octane results in higher hp??

If I understand you correctly, you're basically saying that higher octane doesn't help you make any additional hp...it just helps you make it SAFETLY? Which means that you must already be able to make that kind of power with your setup, no?

That's still pretty damn good. I'd like to see someone making anywhere close to that on ANY set of sequential twins...

So do you think the FD can generate those kind of #s as well, assuming the turbos could be retrofitted? (take into account inefficiency of the rotary)

Well the 2JZ is practically indestructible, so I'm not surprised. What I'm curious about is, how well did the TURBOS hold up? Is 20+ psi on them like running 15 psi on our stockers (prone to failure)? You said 3 years, so I'm sure it's not like running 18psi on ours (good for like 4 passes LOL)

Yea, I know, I know. So I've been told lol. But where's the fun in that??

 

Chris was running 24-25 psi on race gas before he went to a single turbo, and I know for a fact that they'll easily hold 20 psi to redline, because that's what I ran for the 3 years I used the Supra for my daily driver. BTW, at the end of that 3 years, my compression numbers were incredibly strong and within 2% from cylinder to cylinder

very impressive....and a testament to Toyota engineering

Jim, what oil were you running and how often did you change it?

 

Only by allowing you to run more compression or more boost than you could safely on pump gas.

Actually, you want to use the lowest octane you can get away with, because higher octane fuels burn more slowly, and you want to achieve peak combustion chamber pressure precisely at TDC. That's why you typically advance timing with higher octane fuels, to start the burn sooner. In fact, you can actually produce less horsepower with high octane fuel than you would with pump gas if you don't change timing to compensate. Just throwing C16 in the tank of your average car will most likely have a detrimental effect on power, not to mention shortening the life of the 02 sensor(s).

Yes. The power doesn't come from the gas. The power comes from the ability to run more boost or compression safely, as I stated above.

Less displacement, less efficient... hard to say. You'd have to calculate the flow (in cfm) produced by a pair of the MKIV twins at X boost level and then compare that to the cfm produced by a known FD combination. Since we're only concerned with how much air (fuel isn't really a concern, we know the FD is going to consume more of it) is going into the engine, if you have a known "baseline" for the FD, you could make a better comparison.

As far as efficiency, 22-23+ psi is comparable to 16-17+ psi with the FD twins. 18-20 psi is roughly equivalent to the 14-15 psi range with the FD twins. Chris eventually burned up his twins at 24-25 psi, which is what prompted the switch to a single, IIRC.

 

I dug up the bill of sale...

Cylinder 1 - 163 lbs.
Cylinder 2 - 161 lbs.
Cylinder 3 - 159 lbs.
Cylinder 4 - 160 lbs.
Cylinder 5 - 163 lbs.
Cylinder 6 - 160 lbs.

Mobil 1 10W-30 synthetic, approximately every 3,000 miles.

 

Something from the T04 family, possibly a T04B or T04E. Maybe even a T58 or T61. Ceramic ball bearings are the way to go for quicker spooling.

A bigger fuel pump and a Power FC or another aftermarket fuel management system. Keep in mind that 14 psi with a single is not the same as 14 psi with the stock twins. The efficiency gained reduces outlet air temperatures and therefore produces a denser air charge than the stock twins can. Denser air means more air molecules, so you'll need proportionately more fuel to compensate.

 

Gotcha about the higher octane part. I didn't know that...good stuff Jim. NOW I know why they increase the timing....(a lightbulb just came on somewhere LOL)

Yea....and I'm sure you know an approximate baseline for the FD, no? What I'm trying to get at is to see just how much power seems realistic w/ this setup. Nothing I'mma hold you to. You scoffed at Stephen's #s, so you obviously have diff #s in your head hehe. Share 'em If I knew how to do it, I would...

Nice...(the 20psi)

 

Huh??? I understand the chemistry behind it very well....but where'd you gain efficiency from, just by virtue of going w/ a single?? What's reducing the outlet air temps? Is it just because twins have two turbos, so they generate much more heat than just one turbo?

 

"Small" street turbo was the way I was going with my Supra. In fact, I bought the RPS T64 kit below just before I changed my mind and bought a Z06 instead.

 

No, in fact two turbos are almost always more efficient than a big single producing equivalent output. The compressor itself is responsible for the gain in efficiency. The larger turbo doesn't have to "work as hard" to produce the same air flow.

Think of it this way... the stock twins can only move so much air. In order to produce 15 psi, they have to spin at extremely high speed. Surpassing the efficiency range produces an incredible amount of heat, which is why forcing the stock twins to work too hard produces superheated air, necessitating the use of high octane fuel to help prevent detonation. In contrast, a bigger single can turn at lower rpm and produce the same output while heating the air less. The downside, obviously, is that it can take longer to get it up to speed because of the increase in mass of the cartridge.

 

Jim, you're gonna have to start charging Newb for this spoon-feeding of Internal Combustion Engine/Turbocharger Theory 101....

 

So what is the final conclusion? Supra turbos "could" work? Had anyone ever done this?

Jerry

 

"There isn't one", "could work, but likely not worth the effort and expense", and "no, not to my knowledge".

 

Kento, I know you're just kidding, but FYI, I'm not asking because I'm too lazy to do the research myself. I'm asking because I simply don't have the time to do it myself, by any means.

As much as I'd like to dedicate some time just for reading up on mechanics, esp. as related to the FD, I can't. I'm pushing 100-120 hour weeks, trying to make it through med school. So time is a luxury I simply don't have...I'm struggling to finish reading all what I HAVE to read (and trust me, it's a LOT), and when time allows, catch up on some much needed sleep. Picking up a book for leisure simply isn't an option at this point in my life. But I pick up what I can from the forum...and ppl like Jim, Mahjik, and Rynberg have been VERY patient and helpful w/ me and my newb questions . And believe me, I very much appreciate their efforts in schooling a newb like me.

So for now, getting what I can from the forum is as good as it gets, and even that is limited to when I'm taking a break here and there...

~Ramy

PS...hey, I have no problem answering newb questions about disease and medicine...hehe

 

Hey Jim...I know you said Chris Bergemann at 484.9 rwhp, 483.1 ft-lbs, stock twins, no NOS. Someone else beat him...

Tony (TT_6SPD_95 on Supraforums) claims, "My best corrected was 485rwhp/517rwtq. The actual numbers of that same run were 496rwhp/527rwtq. That was obtained on stock twins with no nitrous using 22lbs of boost. 11.22@126 Stock Twins, No Nitrous, 3,680lbs race weight...50 degrees and no humidity"

I don't understand how he made that much more torque tho...

And the Dyno Sheet...

 

Keep in mind that Chris' numbers were obtained on a Mustang dyno. On a Dynojet, they would almost certainly have been even higher.

Furthermore, I haven't owned a Supra since September of 2001. You'll have to forgive me for not keeping up to date on their exploits since that time.

 

Good point.

Obviously...just thought you'd be interested

 

Well, I know of as many rx7's that made 400rw in the stock twins as you do Supras that made 485rw on thier stock twins. There have been pleanty get into the 380'srw. All you need is all the bolt on's with a good set of twins that have no turbine wheel damage and 17psi with a good flowing (low pressure drop) IC.

Its generally accepted that the rotary makes anywhere from 10-20% less hp than a good efficient piston engine with the same amount of air. If you take the 500 engine hp that (from what I've found and heard) seems to be the generally accepted safe limit for thier twins before they grenade and subtract 10% (which is conservative) then you come up with 450hp for the rotary. Then go to the rear wheels (15% loss) and you get 382rwhp. Even if they could made a reliable 485rwhp that wouldnt be enough to justify it in my opinion. Once its on a rotary that 485 is going to be down in the low 400's and in my eyes its just not enough to justify all the expense of a conversion.

I'm sure me being able to put on my own pants without help is a big suprise to someone like you that cant.

Stephen