Those are the results we're looking for! Good to see the boost creep sorted. Time to turn up the boost?

So yeah ...turned up the boost to 9psi . This will be as far as I go on pump gas/stock engine.

Spoolup ..... definitely better with this cast manifold than it was with the fabd manifold and same turbo combo.
Boost control ... good but losing around 1psi up top . I'm sure it will be better with a 5-6psi spring vs the 3psi one that's in there now.
Power ..... making over 300whp at only 8 psi .... had to back off the boost cuz it was spinning the tyres during a run at only 9psi (crap tyres).

Excellent progress / result. Looks like a compact and effective design. :icon_tup:

It w/b an exciting development for our RX8 community to have a viable mani & motor mount combo on which to base their build.

Ok , so far the manifold/wastegate combo seems to be working great, but I haven't talked about a couple of other things I'm testing :

New 8" vertical flow intercooler : This seems to be working great . Obviously I'm not running boost as high as before but so far from what I'm seeing, this setup is far and away the best I've ever tried. There appears to be no detrimental effect on engine cooling and IATs are staying within a few degrees of ambient AFTER a run! Need more testing but pretty confident this was a worthwhile upgrade.

OMP modification : Increased flow through the omp (see omp output thread for details) which I'm hoping will remove any need to premix at elevated boost on pump gas (not seeing this as a good idea with high ethanol content) . Too early to tell on this one.

Cuz we all like graphs :

Boost log .....boost cut hits at the blue line . Spooled to 8psi by 3150rpm
https://cimg1.ibsrv.net/gimg/www.rx8...57ec229d35.png


Virtual Dyno at 8.5psi
https://cimg2.ibsrv.net/gimg/www.rx8...84df366ddb.png



Inlet air temp at 15C ambient and 8.5psi 3rd gear log from 2500 to 8000
https://cimg7.ibsrv.net/gimg/www.rx8...55f435e471.png

Old IC at 14C Amb went to 26C ( @13.5psi boost)

EMAP for log a day after above same settings ambient 15C whp came in a bit higher at 320 for this log . Blue line is at boost cut (7700rpm)

https://cimg9.ibsrv.net/gimg/www.rx8...dcd1ab3b4e.png

Brettus,

This is making me so giddy ha! Are you planning on tearing down this stock block and rebuilding for more boost? Or wanting to test the limits of a stock block first?

I have a bunch of REW block parts I am getting ready to sell to rebuild a Renny and get a G30-660 for when this is released.

This really has the possibility to put the RX-8 back on the map competing with S2000, and 350z/370z as a builders car now knowing adding good power is an actual possibility. Engine swapping may soon not be such a considered option.

In for more results :bluesuit:

Glad you see it the same way I do :) .

So this current block is the one that came out of my blue N/A car. It wasn't really in the plan to fit it but I wanted to get this manifold tested and underway. I think it's not such a bad thing to try the manifold on a bone stock engine as that's what most people will do anyway. I don't plan to push it much further than this as I believe around 300whp is the safe limit for the stock block on pump gas both for detonation and longevity.

I'm currently getting another block built which is waiting on machine work being done to lower the CR of the rotors.
This new block will have :
9.4:1 rotors
RX7 apex seals
Dowel pining
Increased oil pressure
G30 - 660 with 0.83 AR housing

Currently the GTX3582 0.83 is spooling way better than I expected it to. Some of this may be due to the porting of the T04B compressor housing I did, but mostly I think it's the added heat retention and improved flow dynamics of the cast stainless manifold. .... I believe the G30-66 with the 0.83 will spool even quicker - MUCH quicker. Excited to see how that pans out.

Probably my biggest challenge will be actually doing the work ... this last install almost broke me !

Do you really need anymore? I think 300 is the sweet spot for a fun, very enjoyable experience on the street.
WIsh you all the best. Keep it rolling.

Cheers
The rx8 is a special car with this power that's for sure - pretty much puuuuuurfect . So no............... I don't 'need' anymore than that.

that 0.83 is a bit tighter than the G25 0.92, better watch emap on the top end at higher boost.

I definitely will be watching EMAP !
But as a matter of interest the GTX3582 made over 400whp on a 0.83 and the emap on that was way higher than the G30-660 1.01 at similar power. I expect the G30-660 0.83 to actually outperform the GTX3582 0.83 in every way.

That's exactly what I would look for on my 8, Stock, 300hp, Sunday driver, can care less for records.

Great spool and power results for < 9psi. Not sure if any of us would have thought this would be achievable 5 years ago.

Here's a thought exercise: You mentioned above that you didn't want to push over 300whp. Is there such a thing as maximum safe WHP, or is the maximum safe value a PR, IMAP, EMAP or combination of some or all of these? We've already determined that IMAP(boost) isn't the only factor, and neither is WHP, because reducing EMAP or PR has shown that higher IMAP and WHP values can be achieved before the motor fails. So which of these, or which combination of these is most critical to determining the maximum potential of the motor before it's likely to fail?

Would be good to put together a table of values (e.g. WHP, PR, IMAP, EMAP) showing some maximum values that have been run safely. Hard to do unless you're using the same type of motor build and same type of gas for all results across the table. A formula or rule of thumb could be identified if there were enough data points.

Yeah , great point James .Good to see you still taking an interest !
I tried to list how I believe they stack up in order of importance below.

1/ Fuel octane/latent heat of evaporation
2/ Load (not boost)
3/ IAT
4/ AFR
5/ EMAP
6/ Timing
7/ Engine coolant temp
8/ Engine oil temp

Something like you suggest above would be brilliant if it were practical to get the information.
As you can see .... I rate IAT as a more critical parameter than most and EMAP is lower down the list for me. I think EMAP (while important) isn't as critical as it is for other engines with overlap.
Another one we cant really measure is : Heat soak into the intake tract . I think this is something very much overlooked but also important.

Also : Just added emap to the above charts posted yesterday.

Brett, why don't you think EMAP is as important? I imagine depending on power levels it is more related to the temperature at the exhaust ports and potential side seal failure, is there a correlation between HP and EMAP where you should be looking at reducing EMAP to go higher on HP reliably?
I find this discussion super interesting as my car is mostly used on track, with fast long straights (suzuka) and reliability and HP are something i'm looking at the most.

I do think it's important. All the things on that list are important ..... but what I've noticed with EMAP is that it doesn't have as much effect on power with the Renesis as it does with other engines. I would put this down to the lack of overlap and the limited carryover of exhaust gas between cycles.
If you compare say ... a Greddy setup to my setup ..... where the Greddy could have as much as double the emap ...then yes ...big difference. But comparing different AR turbine housings on the same setup ..... barely noticeable (apart from the spoolup difference).

That I understand, I was thinking more on the lines that to a certain power level, EMAP should be kept to a certain value or lower for engine longevity. Specially for us guys that track our cars and do many laps. EMAP seems to be more critical towards reliability than in piston engines.

3150 to a 8000RPM limiter. Mighty impressive, mister, mighty!

And I do like that you check out how it work with stock OEM block, as you say, if its possible to get what you're after, less work, happy days!

which is why you should also expect that the G25-660 0.92 is the choice for absolute best spool to power ratio once the MOI and other differences are considered, including the smaller fitment size.
.

Maybe ... but moi isn't the only consideration . Turbine efficiency also comes into it and that can vary going from one turbine to another on the same compressor. Interesting to note that Garrett doesn't give a max. efficiency figure for the G25 turbine !

Prettty hard to put a number on it ... I wouldn't like to guess. But whatever it might be would vary relative to all the other possible problem parameters . The possibilities are infinite.

more so at high Pr, but it will have to be quite a bit to make up this much difference at the Pr ranges we’re discussing (difference between Blue (G30-0.83) and Black (G25-0.92) lines in middle of the overlay below)

which wrt MOI we’re talking about the mm diameter differences between 54i/49e for G25, 60i/55e for G30, 68i/62e for 3582 in heavy material down at low rpm, the difference will definitely be there coupled with the same mass flow moving through a smaller flow path (higher velocity)
https://cimg9.ibsrv.net/gimg/www.rx8...b8fb0e939.jpeg

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Nice comparison. You are probably correct with your assessment ... certainly looks that way on paper. I do like the fact that the G30 has the 1.01 option though (for those that want to track their cars) and that it's now a known quantity.

Pic showing close up of IC install ..... this seems to be working exceptionally well so far but it hasn't seen any hot (25C plus ) days yet.
IAT post IC at cruise : 1-2 deg C over ambient
IAT after 9psi log in 3rd : 6-7 degrees over ambient
Engine coolant temps at cruise (cool day 15C) : low 80s
Engine coolant temps after 3rd gear pull ...go up by 1-2 degrees C only
Note : the inlet hose does block the left hand side air to the radiator but the right hand side is unobstructed. I think this will be enough even on hot days on track but still to get that test.

https://cimg8.ibsrv.net/gimg/www.rx8...5fa7bb8601.jpg

Brett, do you find the thin wire mesh has significantly better airflow than the original plastic grill?

The plastic grill is more restrictive than it looks .... I'd say the mesh is better but not sure that it makes much difference TBH.

I like it. If nothing else ...as you say it's less restrictive than the plastic OEM jobbie, and still provides some protection for the IC and rad. That's actually my next minor upgrade. I already have the sheet mesh I'm going to use.

another sneaky dyno .... Feels great at only 9psi I have to say.

https://cimg2.ibsrv.net/gimg/www.rx8...2beec8c8c7.png

Brett

In an earlier comment you mentioned that 9 psi of boost was as about as high as you would go on pump gas, is that on 91 or 94? (some stations here have a 94 option)

This is on 98 octane (equivalent to 93-94 in US) . The particular gas (Gull) is actually 95 octane with 10% ethanol added to get it to 98 vs say BP98 which has no ethanol . Have talked to several tuners here and they agree it's the best pump gas we have here in NZ.
We actually have one station selling 100 octane here which gets that rating through the use of olefins . It's utter crap for high performance use ....don't ask how I know !

300 wHP w/ a 4k torque band is very nice for a DD. :yesnod:

Daym ..... this IC setup is awesome ! This is some hard driving on and off the throttle for 25 mins .

IAT doesn't go more than 4 degrees above ambient and engine temp is stable . Previous IC would gain 13-14C on a similar run.

https://cimg7.ibsrv.net/gimg/www.rx8...b85aaf3e03.png


Same piece of road with the old IC (slightly warmer day)
https://cimg1.ibsrv.net/gimg/www.rx8...b9bf223e66.png

Sorry catching up on the thread this morning, MOI, what does this stand for? Trying to follow the g25 vs g30 debate but not understanding.

Moment Of Inertia.
Which spools faster, as I understand.

G30 AR 0.83 vs G25 AR 0.92
Spoolup
MOI - G25 wins due to smaller turbine
Turbine efficiency - G30 wins........... probably , although no figure given for G25 .... generally turbines get more efficient as they get bigger
Turbine flow - G30 wins being slightly tighter in PR range we will operate in
End result ... bugger all difference but probably slightly favoring the G25

EMAP
Turbine efficiency - G30 wins
Turbine flow- G25 wins
End result ... bugger all difference but probably slightly favoring the G25

That's how I see it ... but with the G30 we will also have the AR1.01 option that blows the 25 out of the water for EMAP. Plus ...I've already tried the G30 and daym that G25 turbine looks soooooo small it scares me ! lol

not quite, what will ultimately matter wrt efficiency is corrected mass flow rate

so the G30 may have more efficiency as it approaches the peak flow rate at higher Pr values, but it's flow rate with the 0.83 housing is lower than the 0.92 G25 housing as demonstrated in the graph above. At question is what the efficiency difference is and where and how close do they become to each other once mass flow is corrected.

That’s what my post is referring to, because there’s an 8 - 10% flow difference in favor of the G25, so the efficiency difference of the G30 housing has to be quite large to overcome that. Which it can’t do at the very low end and will be slower to hit peak boost as the G25, but likely will at the high rpm with less emap and/or more peak rpm range, etc..

Because that efficiency difference is greater and more in the G30 housings favor at high Pr than low, but we’re likely only going to see around 2.3 Pr peak or so on a Renesis unless you intend to really cram it in early with high boost at low rpm and then taper that off at high rpm. That seems unlikely since nobody here is that sophisticated and/or willing to spend the money to bring it into play with the means to have full-on boost x rpm x gear strategy, electronic wastegate, etc. … or at least not yet.

So imo this shows itself on a reciprocating piston engine application, because if you’ve been following the G25-660 results it comes up a bit shorter than expected because they’re up in the 3.0+ Pr range. So the turbine not only becomes less efficient there, the peak compressor flow is also lowering due to how the map tapers back. Whereas peak -660 compressor flow is at approx 2.55 Pr. So imo this plays out more in favor to a 2-rotor. More so with an earlier 13B with the divided 0.92 T4 housing piped in from each exhaust port separately.

Not everyone will agree, but I think that T4 housing also has an advantage on a Renesis too, but am willing to let it play out rather than banter on for or against it.
.

Even when I'm agreeing ...we disagree. LOL

I hear you ... I just think the differences will be smaller than you do.

just like when somebody was trying to put a G30 0.83 housing in your lap. :)

but I also agree that peak power is in the G30’s favor. With a 7000-7500 rpm limit in the sub-400 whp range on a street car I’m not so afraid of the little guy … but then I’m also thinking E85 fuel etc as well. Otherwise I see it being what everyone had wished the Greddy to be if shooting for the 300-350 whp range. The smaller packaging always helps on a Renesis too.
.

Never disagreed with you on that one. Still haven't tried it though -and things never seem to go quite as we expect so the jury is still out.

there’s always that, lol

Found this in a convo Team was having over on the 7 forum . Don't know who the guy is but he seemed quite experienced .

Link to the thread :https://www.rx7club.com/single-turbo.../#post12478153

except you didn’t include my counter reply, which the debate ended at. It being also what was discussed here in the more recent comments above when we were having more or less the same conversation.

I strongly disagree with some of that, but the one good point he made was that we don’t have turbine efficiency maps. So in the end all that matters is the corrected turbine flow once efficiency is factored in. Which again was already discussed further above here as well as on that thread. The G25 0.92 turbine has more flow to counter against the efficiency difference, but I already conceded that the G30 0.83 is closing in and going to have less emap the far right extreme of the compressor map. It’s never been my assertion to operate the G25 there, but more in the 300 - 400 whp range.

I’m not discounting his experience as was stated in that other thread as well, but by his own admission it was based on earlier Garrett turbos and not the G series. Below a graphic demonstration of why I disagree with him with the following illustrations below. As I stated somewhere on the forum not too long ago, imo the G30-900 makes more sense to me than either the G30-660/770. The 900 will spool a bit slower and the turbine is going to start choking up some to the far right of the map on a rotary engine, at which point the G35-900 makes more sense, but it’s going to be very strong in the 400ish - 525ish rotary whp range rather than running either the 660 or 770 out to the far right of their maps.

I didn’t bother doing this with the G30-600 because it doesn’t interest me over the G25-660; which is a comparison of efficiency island width/range between the 70% efficient points:


https://cimg4.ibsrv.net/gimg/www.rx8...4e49bfe77.jpeg
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https://cimg6.ibsrv.net/gimg/www.rx8...f4200c814.jpeg
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https://cimg7.ibsrv.net/gimg/www.rx8...63e62a4a9.jpeg
.

No need to include your answers as it's just the same argument we were having. His point about blade speed ratios and the effect that has on turbine efficiency ,on the other hand, was something I had neglected to mention. You seem to think it doesn't matter, whereas I've actually seen that effect in some of my experimentation and do think it matters.
Also : you seem to have this notion that the efficiency of the turbine is somehow accounted for in the flow rate. It isn't ......... and that's why it's listed separately on turbine maps. Just play with flow and efficiency on the matchbot software and you will see what effect both have on the outcome.

no, it matters, but again all that ultimately matters is the corrected flow where all that comes together. Which also again, the 0.92 has the indicated map flow advantage that will serve to offset that. And it will mostly come into play on the top end as the 0.83 starts to close the gap.

Not sure why it needs to keep being repeated? When the turbo is running out to the far right of the map that’s generally going to be where that always happens. G25 vs G30 with the 660 compressor or G30 vs G35 with the 900 compressor.
.

Ok ...it's just some of your comments led me to believe you thought that corrected flow was the end all parameter for the turbine side.
The thing is we actually don't know what the efficiency number is for any of these combinations. That's because they only ever give a maximum number . To try and give the numbers for all combinations of exhaust housing, Pr and flow rate would be a ridiculously complex exercise and 99% of those looking at that info wouldn't have any idea how to interpret it anyway.
That's where spdracers comments are valuable as it sounds like he has seen and understood the nuances that exist in this area.

Edit : for interest , I had a play in matchbot to try and get a sense of how turbine efficiency vs turbine flow affected emap.

So (and this is just approximate) the g25 0.92 outflows the g30 0.83 by 1 lb/min in the range I'm operating the turbo. To get the same difference in EMAP via turbine efficiency would take a 4-5% difference in efficiency.

G30-900 1.06 a/r ?
 

Team, The map you’re showing for G30-900 has 1.06 A/R were you referring to that A/R for 525’ish range hp turbine efficiency/flow?

feel like I’m talking to the wall

it’s bad enough I have to keep repeating my words, but now Brettus repeats my words like he’s making a point against me.

You don’t have a race car where you’re hammering it at max rpm for 20 or 30 minutes continuously. Running out there for a bit is what a street car typically does. That’s not what would generally be called “where it operates”. Where most street cars operate is in the range of where the G25 has an 8-10% flow advantage that’s being glossed over. I’d argue that the G30-770 is the better choice for 400+ over the 660, because then both compressor and turbine efficiency are coming into play. That’s why I see the G30-660 as sort of the most odd man out of the three G30 compressors.

Yet if you actually compare the maps above you can see the 900 is almost right on top of the 770 on the right, but has a 10+% compressor efficiency advantage on the right. Seems like you’re kind of mixed up or confused B, which is why I don’t think you’re seeing the overall points where that guy is off. Because I’m not discounting his experience, but his experience wrt the 900 compressor is not correct imo due to be based on the previous less efficient versions. It’s just what the marked up map above indicates and I already conceded the G30 is closing in and passing the G25 at the very top end as Pr increases, at least 4 or 5 times now.

The thing is you haven’t been operating much over 2.1 Pr or so. When you go higher you’ll be ramming it over all the way to the far right which I wouldn’t want to do with either the G25 0.92 or G30 0.83 and a 660 compressor. The bottom line is the 660 with either the G25 0.92 or G30 0.83 is too small for 400+ on a 2 rotor imo. Not saying you won’t get there, and I agree the G30 is better for that, but the G30 having 3 different compressor options allows for a pretty good analysis that to me indicates the 660 and 770 could just be eliminated. The only reason to have them is for tight fitment applications where the 900 compressor won’t fit. The compressor efficiency suffers on both compared to the 900, but for a competition car and/or 550+ whp then I’d move to the G35-900 instead.

So on those maps above, the 1.06 housing is just my preference that was listed in the text description, having formulated those for an REW application. The lines only indicate where 70% starts on the left and then ends on the right for the two boost pressures and what the lbs/min width or range is between those two points. Which helps define how efficient overall a compressor is. Which again at 20 psig, the the efficiency/flow is really close between the 770 and 900 on the left, but on the right the 900 compressor leaves it in the dust @ 70 lbs/min as the 770 is on it’s last dying breath. Since the turbine is the same, then that compressor efficiency difference is what separates them and is why I’m saying the 660 and 770 aren’t that interesting to me.

So now Brettus, rather than a 660 with 0.83, think about a 900 with the 0.83 instead. It will spool a bit slower due to the larger 900 compressor and a bit less compressor efficiency initially, then the compressor will be coming on hard pumping more corrected airflow for the same turbine load. So if that’s where you “operate”, then you really need the 900 and the much higher compressor efficiency from 50 - 60 lbs/min. Which illustrates my point. Both compressor and turbine efficiency matter. So then if you’re experience is from a generation or two prior, and that’s the basis for trying to make assessment on the new G-series using those old efficiency references, then you might possibly be missing why they moved to a new generation turbo design in the first place. .

Again, study the 900 compressor map compared to the other two.
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Interesting discussion, I've been trying to figure out where all this fits for a Renesis with under 400whp and track use, looking for reliability and low EMAP, which means keeping it below 14 psi.
Sounds like there would be different turbo options depending on what application you have, street car with a G25 for quick spool, G30 for a track car for more reliability under continuous high loads.
Reason for asking this is that i'm using the MM GT3071R kit which currently has been pretty reliable albeit at a somewhat reasonably low boost of 10 to 12 psi. Looking to optimise my setup for track use while keeping it a low mount.

Because you aren't getting it .................... that's why!
That 8% you talk about as the difference in flow is not going to matter ... the G30 0.83 will perform just as well as the G25 0.92 because better turbine efficiency of the 30 will largely make up for more turbine flow of the 25 and EMAP will be so close it wont matter. It pains me to even discuss this because we are just nit picking about a tiny differences.

Also , I have no interest in the 770 or the 900 because...........................not only will they not fit in my configuration, but they will have slower spoolup and the added flow they provide isn't necessary on a Renesis. Your analysis would be useful over on the rx7 forum but here ...not so much.

That's why the 30 is the much better choice. The 0.83 can be for street cars wanting quickest spool and the 1.01 for track cars wanting lower emap. You don't have to change out the whole turbo to achieve either.