The rotating assy was balanced for 10,250 but,I'm thinking of 9k for redline for durability and also it's a street car so I'd like it to have a usable wider power band, not just all up top. In the end the redline will be set depending on how my setup works.

 

what turbo you thinking of using on your setup?

 

I have a GTW3884R at hand with the 67/84mm (950hp rated) compressor but it might be a tad small on the turbine side 74/65mm although I have a few housings to try, 1.00, 1.15 and 1.32 a/r.
If it doesn't work to my liking I'm thinking of the G40-1150.

 

I think the GTW3884R 67/65 was one of the predecessors to the current gen G35-1050 68/62. Best of luck with your turbo choice. Excited to see how the 67/65 performs!

I spoke to Mark last year about his semi-PP setup. He’s running a custom turbo with a 75mm compressor, 76mm turbine, and a 1.25 A/R, paired with a full 4" downpipe and exhaust. At 14.5 psi boost and 10.8 psi EMAP, he hit 100-200 km/h in 5.95s at 10k RPM on a completely stock FD gearbox, holding 3rd gear to redline! I have the Dragy report but not the video overlay, so once he turns up the boost this year, I'll update the thread with his results. If a manual gear change was involved at 9krpm the 100-200 km/h time would have dropped by 0.3-0.5s to an approx time of 6.25s - 6.45. Quite impressive for street use imo with hardly any boost.

 

Wow that's awesome. A friend was able to tune a large street port with pump and 50/50 pre-turbo water meth to over 600whp on a Precision 6766 1.0a/r at 30+ psi. Don't know emap unfortunately.

This gave me hopes I could achieve similar at lower psi on the 6765 because of the semi-p. But who knows, maybe the semi-p doesn't like the 65mm exhaust 😅.

How are you guys running the 100-200? Start in 2nd and go through 2 shifts or start in 3rd at lower rpm?

 

That sounds very promising. Same I haven't got any emap data for my G35 but so far so good.

Think 15-20psi and your turbo will be maxxed out but i think it will do well. As you suggested, if it doesn't work out, just a case of swapping the turbo out.

Everyone running the stock FD gearbox streetport/bridgeport is starting their runs in 3rd gear around 3krpm - WOT to redline and shifting to 4th gear WOT to 8krpm to get both the 100/200 km/h and 60-130mph where possible.

If your're doing a full send like Mark with a semi pp then 3rd gear to 10k rpm

 

In a few weeks, I'll be getting my FD back after upgrading the fuel system. The setup includes:

• Twin Walbro 450 high-pressure fuel pumps
• E85 AN8 lines
• 2x 1500cc injectors and 4x 2200cc injectors

This setup will allow me to safely push the boost to 30 psi. While waiting for the upgrades, I was reviewing real world data from previous Draggy runs, and I came across something that might interest 13B Streetport/Bridgeport owners looking for real-world performance insights.

Before Omar's sub-4 second 100-200 km/h runs, he posted a draggy time of 5.18 seconds at approximately 28 psi.
Precision 6885, Bridgeport, DCT


Nath's recent run at 29psi was strangely also completed also in 5.18s.
G42 1200
Dog Box
Bridgeport



The key takeaway being two impressive setups running a 13B bridgeport with a properly sized turbo, both pushing similar boost levels and achieving 100-200 km/h times in the low 5-second range.

Omar kindly shared a setup from one of his customers featuring a G40-1150 T4 with a 1.19 AR on a 13b bridgeport, running 25 psi. The car uses the stock FD gearbox, so there are two granny shifts involved. Despite that, the time is still incredibly impressive. If the owner were to re-run the test with dragy overlay, I’m confident they could hit mid-5s for the 100-200 km/h range, 5.5-5.6s is potentially possible. However, because 2 manual shifts were involved the time was 5.94s



The fact that a G35-1050 is already managing high 5s is pretty impressive, but I’m starting to think there might not be much more to gain with it—maybe a 0.1s-0.2s improvement, potentially with very high emap or serious consideration given to control boost beyond 7krpm.

The trend suggests larger turbos like 6885 or a G42 1200c 73/75 on bridgeport engine with dct or dog box running 27-30 psi boost to be able to run low 5s 100-200km/h in the real world.

I’m considering swapping to the G40-900 and turblown uim sooner and calling it a day with the G35.

 

"swapping to the G40-900"

a really nice turbo for 560. efficiency falls off a bunch as you head to 600. 600 isn't a great place to be w a stock trans.

the new ACT organic/sprung double disc would be a help

 

It's purely speculative, but I'm hopeful that the G40-900 at 26-27psi can reach mid 600hp figures, especially with the Turblown UIM. The 100-200 test will give us a clearer picture of its real-world performance and whether the small compressor/large turbine setup translates into faster times. For context, the 1150 at around 25-26psi ran a 5.94s and could likely hit the mid-5s range. Hopefully, the G40-900 can perform similarly, time will tell.

The stock gearbox is a weak point, and if it fails, I think it’ll be time for a DCT. That being said, the replacement gearbox is low mileage that has seen stock power for its life cycle. Where as my box which failed...had close to 320ish 100-200s with the vast majority starting in 3rd gear....which eventually let go. Hopefully, the replacement box lasts for a little while.

 

"hopeful that the G40-900 at 26-27psi can reach mid 600hp"

while i might be getting a bit too **** here, mid 600s means 650 and 650 takes about 87 pounds. i don't see that w the 900. max delivery is at 22 psi is 81. that is at choke and 58% efficiency so you don't want to be there. bad for the turbo, bad for the motor... high IATs.

a really appropriate option for mid 600s is the G40-1150. (you know i am going there)

87 pounds is now in friendlier territory. 75/76% around 22 psi. that's what the map says. i can tell you i was there... 22 psi 628 hp. the efficiency is real, the air coming out of my turbo at 8100 rpm/600+ hp was at 242 F! IAT into the motor was 71! measured by a thermocouple so accurate. my EFR 9180 did not spool as fast, had higher EMAP as well as 75 F hotter coming out of the turbo.

the G40-1150 has always been ahead of my pedal. it is a 790 rw rotary hp turbo but you don't have to go there.

try it, you'll like it.

 

At the very least install a shaft speed sensor and make sure your wastegate strategy has a backstop to protect from overspeed if you want to push the limits on the 900.

 

I might get booed here but consider pre-turbo injection setup to spray at the higher boost levels to help max out the 900. It's not as discussed as it once was but it's a proven method when properly done.

also, this may not be the thread for this question but since we're talking flow and whp, when we say 650whp = 87lbs is this with which fuel, gasoline, e85?

 

"flow and whp,.. with which fuel"

the relationship between flow (pounds air per minute) and turbo rotary power has been established on the dyno during the last 25+ years.

the number that works pretty well is 7.5. if you run a turbo to 60 pounds of air you would multiply 60 times 7.5 and would find 450 rwhp.

no matter what fuel you use, as long as it doesn't contain oxygen, available oxygen within the charge air sets the power limit. while the 7.5 relationship was established w gasoline, since it relates to the oxygen it is not fuel related.

you can make 450 on gasoline, ethanol or methanol. each will require a different amount as each have differing BTU content per gallon.

the relationships between the fuels are as follows:

gasoline 116,090 BTUs per gallon
ethanol 76,330 BTUs per gallon
methanol 56,800 BTUs per gallon

fuel is just a catalyst to burn the oxygen.

non mechanical challenges as to power production are primarily burning all the available oxygen molecules. of course there are lots of other factors but burning oxygen is job one.

 

There will be marginal pumping efficiency gains from the evaporative cooling gains of more oxygenated fuels requiring slightly less intake pressure (and hence exhaust pumping losses) to achieve the same mass flow but until you go to to nitromethane or hydrazine available combustion energy is effectively limited by choke flow at the compressor.

I'd agree aero forced cold air intake and some some AI/fuel evaporative cooling pre-compressor will get the most from a particular turbo. It has the potential to stretch the effective power range of a fuel system too by allowing a higher diffenertial/requiring less differential to get a given fuel quantity into the engine if running some tertiary injectors pre-turbo as well.

 

A Tilton flow control valve would definitely help your stock trans. Certainly not going to make it 100% reliable at 600whp but it is a no brainer give the price.

https://tiltonracing.com/product/flo...BoCfD4QAvD_BwE

 

"A Tilton flow control valve would definitely help your stock trans. Certainly not going to make it 100% reliable at 600whp but it is a no brainer give the price."

agree.

here's the other item... IMO the Exedy double disc is now a no go as it uses cerametallic frictional surfaces which are pretty close to on/off.

ACT is organic and beautifully sprung sprung so as to be easy on take up. being a double disc it holds all the power.



you'll probably still lose the teeth in 3rd gear though.

 

I have a direct clutch services cushioned, sprung ceramic, my 4.77 diff with the OSG gearset makes first a fair bit higher than standard (same first as one of the T56 magnum sets) and it drives fine in traffic.

If people want a softer twin plate they should probably look at the HKS LA organic or ATS carbon too.

 

I ran a Tilton flow valve on the stock gearbox, completing 320+ 100-200 km/h runs, but the gearbox failed on track at just 15 psi of boost—third gear gave out. They will all die eventually. You can find more details about the flow valve and third-gear failure in earlier posts. The clutch used was a Comp Stage 4. If you're concerned about the torque capacity, you might consider switching to an Exedy Stage 1 clutch paired with the Tilton flow valve. This setup will help preserve the gearbox and diff, although 100-200 times may be quite a bit slower due to potential clutch slip in 3rd and 4th gears. It depends on the owners preference for gearbox/diff reliability over peak performance.

Personally my preference is to get rid of the flow valve and go dct or zf8 this year.

 

I agree, on paper the G40-900 seems to struggle compared to the G40-1150 for hitting mid-600s, but the plan is to push it close to its 125k RPM limit, using speed sensors to ensure it doesn’t exceed that. I'll also use 1000c WMI to help manage IATs and should have a clear idea of its performance after a few draggy runs. Worst case, if the G40-900 doesn’t meet expectations, it’s not a big deal—at least I'll gather some real-world testing data.

It will be interesting to see how the G40-900 performs in real-world conditions. If it gets close to the 1150’s potential, the lower EMAP could reduce back pressure, allowing the engine to breathe more freely. This would improve efficiency, response, and provide a wider power band, ultimately making the car faster and more efficient without sacrificing peak number.

 

It's not quite that black and white, it will definitely come on faster but there are balancing acts on compressor efficiency/shaft speed and turbine flow past peak efficiency. I'm not sure you will retain an IMP:EMP advantage over the 1150 approaching 600rwhp.

At least it's literally a CHRA swap into your existing setup and if you buy a complete replacement 1150 if you do want more power you can sell or use the 900 and appropriate housing elsewhere.

 

You're right, it’s a balancing act with the G40-900. I’m not only looking at Garrett’s theoretical maps but also real-world performance. For example, many would think the baby 68mm compressor on the 6885 turbo couldn’t achieve 3.7s to 3.9s 100-200km/h times, yet it does. I believe the 85mm turbine plays a big role in allowing a rotary engine to breathe efficiently, which is why I think the G40-900 could offer similar benefits on a street port engine. Of course, this is speculative, but the 6885 is my inspiration.

The 1.19 A/R T4 turbine housing on the 900 flows 43 lbs of air, giving it a theoretical advantage over the 1150 in terms of EMAP for a street port application. The 900 is more efficient at lower pressure ratios, and while it may lose efficiency as you push it further, finding that sweet spot will depend on real-world tuning and testing. It’ll be interesting to see if the 900 can keep up with its bigger sibling. I dont think it will make the peak numbers of the 1150 but it may come very close to the peak numbers while printing more area under the curve...the 100-200 will confirm the real world result. I already have 100-200 data for a G42 and 1150, so it's reasonable to expect the 900 will likely have a slightly slower time. The real question is - how much slower will it be, or could it be the same? or perhaps create a major upset and be a touch faster?

 

There are a few things that could be done. The one i'm thinking of is that maybe the small turbo gets rid of a shift. i got shown a really old video (this was on tape!) of an Rx3 vs a 5.0 Fox body mustang going around Sears Point, and the Rx3 was in 3rd the whole time, while the mustang which makes way more power, had to shift a lot. Rx3 was faster!

Second, and what you should do with the data, since you have it, is that for 100-200kph you know the RPM band you're using, your advantage would be to make as much power as possible in that band.
in the old Japanese Rx7 Magazine there are a couple of interviews with the guy from Revolution Revolution Online Catalog / TOP??? and in their drag car they were trying to optimize the ~5500 rpm area, basically the RPM the engine hits after you shift.
these new turbos are probably way better for this, but the Revolution car was a T88, with a smaller turbine housing and 50mm manifold. off the top i'm not sire if it was a semi PP or a bridge, but they were in the ~600hp area

it'll be fun to see either way!

 

IDK about smaller turbo.

If you do like the RX-3 and use RPM you might want the larger turbo.

Example-
In an FD with the 5.86 rear gear I have a 100-200kmph run is a 4th gear rip from 5,000rpm to 10,000rpm.

That is exactly where a semi-port with appropriate intake manifol and large turbo makes power.

Ernie T dyno from 14 years ago

 

So 4.3:1 rear and 3rd gear would also be 5,000-10,000rpm.

But its 3rd gear so T______T

 

Unless you can get ~40psi and taper back running close to choke the whole time I think even most manuals with a quick shift will probably have more effective average power with a shift than starting from 400hp? Not many people will actually run to 10,5000rpm either. I'd want a 2 piece shaft with centre roller bearing to be doing that.