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-   -   TeamRX8 4-Port Renesis Street Turbo Concept Thread (https://www.rx8club.com/series-i-major-horsepower-upgrades-93/teamrx8-4-port-renesis-street-turbo-concept-thread-266951/)

TeamRX8 01-06-2018 12:43 AM

TeamRX8 4-Port Renesis Street Turbo Concept Thread
 
So I've been bouncing this idea around for a while about building a turbo RX8 with a single turbo sized to produce a power range skewed mostly for maximum response and torque in the low-med rpm range rather than moderate - big power increase to a 9k redline. Which, this is the opposite of what most people do or want in general with an RX8. Understandable, since it will cost the same either way, so why not go for teh powaaaa ----? I had proposed on the forum here maybe two years ago, and of course all the chicken-little’s screamed the sky was a fallin’… :)

Well, all I'd want to achieve out of this is a super zippy street car that can slice and dice traffic by just stepping on the throttle without having to drop 3 or 4 gears with a high revving scream. Kind of the opposite of what an RX8 is, as supplied from Mazda, but the chassis itself is great for the goal if it just had the oomph. I’m fairly certain that this idea has the potential to offer an engine similar to the 13B-REW that came from Mazda in the 1993 Mazda RX-7 Twin Turbo (FD3), except with faster response, huge increase in low-end torque; both in magnitude and how soon it builds at low rpm, maybe 100 rwhp more (~330 - 350 rwhp is an estimate- only on E85 street fuel, "not a goal"), but limited to a max 7000 -7500 red-line limit. Other advantages are that a single turbo setup eliminates all the complication, transitional issues, and excessive weight associated with the FD3 twin turbo configuration. To me, an RX8 as such a well handling and reasonably accommodating 4-seater chassis, and fitted with such an engine, would have been the car that many people wished Mazda had offered back in 2003/2004.

After crunching a few common numbers, 350 rwhp on a 2-rotor engine works out to an approx. 47 lb/hr mass flow rate. Again, this power point isn’t the real goal, but we have to determine what the max range of the turbo needs to be for sizing it within the necessary power range. Of course the newer Borg Warner EFR series turbos seem to be the rage recently for providing great response and power, especially on rotary engines. To date for a 2-rotor engine most are going with the EFR 7670 or larger frame sizes, which everyone keeps telling me to use instead. Except they recommend this because they never bothered to compare in detail how the two mass flow maps for those turbos compare to each other as indicated below.

https://cimg3.ibsrv.net/gimg/www.rx8...e16cc8be65.jpg

Just the standard 7163 compressor flow map in lb/min mass flow rate

https://cimg3.ibsrv.net/gimg/www.rx8...9a06d9ebfc.jpg


Which when done as above, it becomes obvious that they’re fairly identical across a large part of the mass flow range. However, the EFR 7670 does have a larger turbine which provides the basis for it to also offer much higher boost range exceeding 25 psig or so over the EFR 7163, as indicated the upper LH area of map overlays. The thing is, that’s not where this engine is targeted to perform. So the larger physical size, high boost range, etc. of the EFR 7670 is not necessary because they basically correspond very closely where the actual operating range will be. For a low-mount position the larger size of the EFR 7670 is a big negative (next larger frame size in the EFR lineup), if it even can fit. Also, the smaller sizing of the EFR 7163 is known to have a corresponding increase in response over the EFR 7670, which is one of the primary goals for this concept. Some people said the EFR 7163 is a lot less efficient out on the far RH maximum flow range, which it is, but only by 2% - 4%. Again, we aren't intending to run at redline continuously i.e., not a track car. So this is a moot point to me.

On to the engine choice. While a few people have boosted the lower power 4-port Renesis, most choose the higher power 6-port. One of the primary issues with the 4-port engine is that here in North America it was only available with a junky 4-spd automatic transmission. However, the rest of the world could get it with a 5-spd manual transmission, which is also the same guts as the 5-spd transmission that came in the 1993+ RX7-TT FD3 chassis, but they just swapped out the bellhousing and tailshaft ends for RX8 specific replacements. This transmission is actually considered stronger than either of the 6-spd manual transmissions in the RX-8, and also a much better choice for a turbo engine that can spit out low-end torque to pull the car out of the hole rather than downshift a gear or two.

https://cimg4.ibsrv.net/gimg/www.rx8...4221192a0f.jpg

https://cimg7.ibsrv.net/gimg/www.rx8...5e0e1d3389.jpg


When Mazda designed the 4-port motor they altered the both the intake and exhaust ports location/port timing some to enhance the low end torque for it. The 4-port motor came with a 7500 rpm redline, while the 6-port motor with the two additional APV ports as designed for high rpm power with more aggressive port location/timing for that purpose to achieve a 9000 rpm redline. The 4-port motor actually produced a higher peak torque rating and more low-end torque in general as indicated in the Mazda information below.

https://cimg5.ibsrv.net/gimg/www.rx8...003935c738.jpg


https://cimg9.ibsrv.net/gimg/www.rx8...362a27bb59.jpg


So given the target goals of this concept, I decided that the 4-port motor is the better choice for that purpose. However, the lower-power 4-port motor also requires some part changes if it now needs to handle much higher power levels than it was designed for. As supplied by Mazda, some of the internal parts on the 4-port had their performance design level reduced to lower costs. The stationary gears, the e-shaft, and a few other parts will need to be upgraded to 6-port or higher level aftermarket parts for their higher strength properties. Also, we already had mentioned that the NA 4-port motor was auto-trans only in North America. The rear iron plate where the transmission mounts will also need to be replaced with the manual transmission iron plate, which you’d have to import from overseas. The simple solution to this is to instead buy a imported JDM 4-port engine, which typically can also be purchased intact with the 5-speed transmission; two birds, one purchasing stone. Currently I see them being offered on Fleabay for around $1400 for the combined pair, which isn’t a bad price really, but they also don’t sell very quickly so my suggestion is to instead make a lower offer to try to strike a better deal.

So I’m going to leave this off here for the moment and block a few pages for later revisions, but stay tuned because this might possibly develop beyond the concept stage if the moon and the stars align just right …


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TeamRX8 01-06-2018 12:44 AM

So if this was my personal car, this is how I envision implementing this concept in the engine bay. I'd want a V-mount setup with the radiator on the bottom V- and the intercooler on the top V- and venting out through a hole in the hood. Most pipe the the turbo to intercooler and then around to the throttle body on the UIM. You can see in the photo below, which is an FD3 RX7 of a racing friend of mine that has the usual V-mount/UIM setup.

https://cimg6.ibsrv.net/gimg/www.rx8...bfdd108c2e.jpg

https://cimg2.ibsrv.net/gimg/www.rx8...ad595b1e07.jpg


However, my approach is to eliminate the UIM, put a plenum & throttle body assembly directly on the LIM where the UIM had previously bolted to it. I'd also reconfigure the IC with the plenum tanks on the top and bottom, plumb from the compressor discharge to one IC intake plenum, then plumb the other IC discharge plenum to the throttle body on the LIM. This shortens up the piping quite a bit, especially when compared to front mount ICs that might be 3x - 4x more if not longer. This supports quick response from the time the compressor starts spinning up to to the to when it reaches the intake ports. There is much less volume to compress between the two end points that count. Some would argue that eliminating the UIM is going to kill low-end TQ. That would be true on an NA engine, but torque from this engine will come from the turbo being responsive and kicking in earlier than some people might suppose possible. That's how I see it anyway. It could prove otherwise, but until the photo below is a rough approximation of how I see the engine bay laying out with this concept.

https://cimg8.ibsrv.net/gimg/www.rx8...77e84ca5d9.jpg


My intention would also be to eliminate the thermostat housing assembly and convert to an electric water pump setup. What this does is to clear away the radiator hoses and T-stat body in that critical space area on the RH side of the engine and provides a freer path for the turbo inlet piping to pass through there. It would also incorporate a custom engine mount/bracket setup to on the RH side eliminate that turbo inlet piping limitation as well. The inlet pipe can more or less run straight up into the bumper opening area for fresh air.


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TeamRX8 01-06-2018 12:44 AM

Regardless of the negative comments from certain people, the general results have already been proven for a higher level of performance using the EFR 7670 turbo, which we already determined is pretty much the same flow map performance as the EFR 7163 in post#1 above. The difference is the EFR 7670 is the next frame size up for the BW EFR turbo lineup. It has a larger more free flowing turbine than the EFR 7163, which again we see that in the turbo flow map comparison where the EFR 7670 can run much higher boost levels than the EFR 7163, but that range/area of the map isn’t used or needed for what’s being proposed here.

The EFR 7670 results are also made using the earlier 13B with peripheral exhaust ports, which that engine generates much higher exhaust gas energy and can use that to spin up the larger turbine assembly well. The counter to this is the EFR 7163 being a smaller frame size and turbine assembly is going to help make up for the Renesis engines lower exhaust energy to provide, in my estimation, an equivalent response. The EFR 7163 turbine assembly is not only tighter and lighter, it’s a slightly different design than all the other EFR turbos due to it originally being designed and used in the Indy car race series.

It’s not just lighter than the EFR 7670 turbine, but when you compare the BW EFR turbos to an equivalent Garrett turbo, the EFR turbine wheel is generally about 50% lighter than the Garrett turbine wheel. This is one of the main reasons that the EFR turbos pretty much trounce a Garrett turbo in both response and how soon boost builds at lower rpm. The turbine needs to get up to around 120,000 rpm, so it only makes sense that if the weight is cut in half that it can get moving and up to that rotational speed a lot sooner.

If you want to compare the EFR 7163 to a Garrett turbo, it’d be equivalent to a GTX3076. Except they’re not really equivalent as the EFR 7163 will outperform the GTX3076 in just about every regard, including max power potential. You can see that here in his linked webpage where the EFR 7163 was dyno tested against a number of other Garrett turbos on a Subaru piston engine. The EFR 7163 proves to pretty much dominate in every test:

https://www.perrin.com/blog/post/bor...-test-and-tune


And then of course is this well know result of the peri exhaust port 13B using the EFR 7670 on TX7Club by member BLUE TII. Which again, this was using a higher power level target than I’d be going after, but generally speaking the low-mid range torque and power levels indicated here should all be within reach of the EFR 7163 as I’ve proposed. The low rpm response and TQ output is what we’d be looking for with the EFR 7163:

https://www.rx7club.com/single-turbo...esults-1070794


https://cimg3.ibsrv.net/gimg/www.rx8...9d27475ce8.jpg

TeamRX8 01-06-2018 12:45 AM

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TeamRX8 01-06-2018 12:45 AM

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TeamRX8 01-06-2018 12:46 AM

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TeamRX8 01-06-2018 03:13 AM

Which there's a guy that has an EFR 7163 on an RX8 6-port and goes by the name "Punchy Lightbeer", which kind of matches up I think :lol:. He's blown maybe 4 or 5 Renesis engines because he guesses mostly. Before the EFR 7163 he had a EFR 6758 with 0.64 AR, which of course blew the engine. Guy seems to have the money and parts, but maybe not much technical knowledge about what he's doing. Sometimes his car goes full boost at 3400 rpm, other times at 4500 rpm, so something isn't setup properly. I don't like how he piped the turbo manifold either, plus he has a smallish cat converter, probably too restrictive exhaust overall, and lots of messed up stuff like that in general.

Some of his parts are shown in the vid below, but you can see more and some dyno runs with the inconsistent boost up etc. on his youtube home page. He did get about 290 rwhp on 9 - 11 psig boost range. IMO he's doing it all wrong so I personally wouldn't use any of this to judge what this turbo is really capable of or as anything substantial either for or against the proposed concept of this thread.

Here's what he wrote on the vid below, kind of tells the tale if you get the idea:


So I took out my Renesis and found a hairline crack in the front iron. Also the rotor side seals were not gaped properly and have dug gouges in the center iron. So I've remortgaged my unit again to buy a new motor and new gearbox because my syncros were too far gone to change gear quickly. I took out my engine because water was getting in the oil plus I destroyed my previous EFR turbo by letting the waste-gate open too far hitting the turbine. So I had to get my 4th turbo and thought I should go back to a rear housing A/R of .85 (The .64 EFR6758 was too restrictive anyway) My Garret GT3582 made 245kW atw before so I'm hoping this EFR7168 .85 will make similar power.



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NotAPreppie 01-06-2018 09:42 PM

https://cimg4.ibsrv.net/gimg/www.rx8...be0e68cc21.gif

Mazda Sports Corner 01-07-2018 12:27 AM

Here's a 4 port that made some power

AAaF 01-07-2018 01:00 AM

This can become interesting.

Regarding intercooler, how come you dont look for a liquid intercooler? I'd expect it to be better on a "not race car", due to stored cooling for standstills and less volume between compressor and rotor to improve response. I guess you have considered it, and found it not to be the best option...?

TeamRX8 01-07-2018 01:02 AM

I had forgotten about that one; still had the auto trans. A big Garrett turbo too; boost comes on way late then rockets up all at the end. I seem to recall they cut out the frame/subframe to fit it, but the manifold was decent except I also seem to recall they blocked the center siamese exhaust port and only fed it from the two end exhaust ports only. Makes it a lot easier to pipe that way, but I'm strongly opposed to doing that for a variety of reasons. Interesting, but sort of the opposite of what the concept of this thread is.

Thanks for posting it up.

edit, actually I went back and reviewed the dynos graphs in more detail. It does rocket up from around 3000 rpm, but it seems to be starting from a really low power point there; 35 - 50 rwhp. I can't seem to find any info on what the turbo specifications are?


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Mazda Sports Corner 01-07-2018 01:17 AM

After seeing your plan to use the 4 port the Pac car came to mind.I like your design for the placement of IC and short piping to and from IC. It good to see a new take on turboing the 8.Good luck with the project if you do it.

TeamRX8 01-07-2018 02:14 AM


Originally Posted by AAaF (Post 4848214)
This can become interesting.

Regarding intercooler, how come you dont look for a liquid intercooler? I'd expect it to be better on a "not race car", due to stored cooling for standstills and less volume between compressor and rotor to improve response. I guess you have considered it, and found it not to be the best option...?

No, I hadn't considered that option at all. Generally speaking water to air means more weight, plumbing, another heat exchanger & accessories to cool the water down, more complications in general. On the surface it doesn't seem like a good idea to me, but I suppose I can look into it more

AAaF 01-07-2018 03:44 AM

Yes, definitively some negative sides. For racing, Id say they weight to much on the negative side, and you usually don't stop a lot for traffic lights:) But for a DD, the energy density in your water gives you slower increase of temp, and the mentioned reduced volume between comp and intake port.

On the plumbing side, there are more components, but it gives advantages like considerably smaller and flexible hoses, so you don't have large pipes stuffing up your space, this mean its easier to give the radiator the best possible placement(V-mount..?), since you only are going to run relatively small hoses between locations. Together, this could more than equalize the extra plumbing.

That was my thoughts, at least:)

TeamRX8 01-07-2018 05:23 AM

Well I didn't detail that there would be dedicated ducting on both the IC inlet and discharge. It's not shown in any of the photos, but essentially it'll be sealed off from the actual engine bay. Otherwise yes, there won't be any air flow through it when the car is stationary. I want to simplify things, not make them more complicated. I don't see myself using a water-air IC. Sorry.

Looks like there was a big thread here on the forum for the Pac Performance 4-port turbo mentioned above:

https://www.rx8club.com/series-i-maj...ackage-246821/


After reviewing the Mazda factory engine dyno graphs that I had previously posted above in the OP, which are flywheel hp, it looks like around 40 - 50 hp at the rear wheels around 3000 rpm is about right for the 4-port engine.





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rotarenvy 01-07-2018 03:30 PM


Originally Posted by AAaF (Post 4848221)
On the plumbing side, there are more components, but it gives advantages like considerably smaller and flexible hoses, so you don't have large pipes stuffing up your space, this mean its easier to give the radiator the best possible placement(V-mount..?), since you only are going to run relatively small hoses between locations. Together, this could more than equalize the extra plumbing.

That was my thoughts, at least:)

most of these are only valid if you have a difficult engine bay. The rx8 has such easy front mount or v-mount piping there is no need for complex piping. The length of piping on a front mount on the rx8 is probably half what you find on most factory turbo cars and has less bends.

Brettus 01-07-2018 03:51 PM


Originally Posted by Mazda Sports Corner (Post 4848210)
Here's a 4 port that made some power
https://www.youtube.com/watch?v=u9jmmCLJ5Wo

Looks ok when compared to some renesis turbo setups but terrible when compared to an rew. Very narrow power band .They say in the thread 19psi to achieve those numbers .... I'm surprised they didn't need more boost than that . Must have been a fairly big turbo.
Was there ever any news after this dyno or did it fade away after an engine or trans failure ?

rotarenvy 01-07-2018 04:38 PM

what makes the 4port a good choice for turbo?

is it more room from the simple inlet manifold or is it the port timing amd more scope to port the motor?

now with the new adaptronic the ease of swapping to a 4 port is now much more viable.

Brettus 01-07-2018 05:16 PM


Originally Posted by rotarenvy (Post 4848256)
what makes the 4port a good choice for turbo?

is it more room from the simple inlet manifold or is it the port timing amd more scope to port the motor?

now with the new adaptronic the ease of swapping to a 4 port is now much more viable.

To me it seems a good choice for what Team is trying to achieve . The peak power potential is limited but using that turbo it would be anyway - especially on a 6 port.

rotarenvy 01-07-2018 05:54 PM


Originally Posted by Brettus (Post 4848264)
To me it seems a good choice for what Team is trying to achieve . The peak power potential is limited but using that turbo it would be anyway - especially on a 6 port.

dunno they are still making 400hp. from the pac web site "The Pac Performance Stage 4 upgrade is the same package as used on the Mazda Australia Targa Tasmania cars ...". You don't start with the low power engine in racing unless there is some benefit.

Im guessing it is the porting potential. The 6port has never been the choice for turbos for that reason.

the higher torque of the 4port would be in the port timing and the longer runners which will move (disappear?) with turbo porting.

This is going to be an interesting build if it eventuates.

Brettus 01-07-2018 06:16 PM


Originally Posted by rotarenvy (Post 4848270)
dunno they are still making 400hp. from the pac web site "The Pac Performance Stage 4 upgrade is the same package as used on the Mazda Australia Targa Tasmania cars ...". You don't start with the low power engine in racing unless there is some benefit.

Im guessing it is the porting potential. The 6port has never been the choice for turbos for that reason.

the higher torque of the 4port would be in the port timing and the longer runners which will move (disappear?) with turbo porting.

This is going to be an interesting build if it eventuates.

Did they actually say they used a 4 port on the Targa cars ? Info is limited on their site . I get the impression they made that 'project 500' car , realised it was a lemon , and moved on.
If you have a look at a 4 port iron ............ the potential is minimal .

Edit : looks like they used a 6 port for the targa car.


Mazda RX-8 SP

Engine: Rotary Turbo
Transmission: six-speed manual, RWD
Power: 205kW
Torque: 300Nm
Fuel tank: 65 litres
Kerb weight: 1280kg
Wheels: 18-inch MAZDASPEED alloy

TeamRX8 01-07-2018 07:30 PM

Well again they used (or so it seems to me) a larger Garrett turbo, though I still haven't found the specs for yet either. So I don't think it correlates to this concept much. Other than they made some decent power numbers for some period of time to show my approximation of 350 rwhp is achievable if the rest of the system can support what it takes to get there.

Not sure I agree with the irons comment, but we'll leave that for another day ... just the same, I'm neither looking for 6-port power potential nor want port timing that supports higher rpm power range. I'm fairly set on this and believe it will prove out well if pursued ... we'll see ...

TeamRX8 01-07-2018 08:04 PM

what you think has no relevance for me, but thanks for sharing just the same

TeamRX8 01-08-2018 03:26 AM

Added more info in Post #3 above that was reserved blank previously

swoope 01-08-2018 03:46 AM

love this.

had a long talk with scott, in the early days.. i said if you make a low mount turbo that makes just 300 whp. and semi reliable i would buy one.

and here we are.

the rx8 platform is about as good as it gets for a hpde track car..

really dont think you need 300 whp if you could just make some tq.

have tracked a gti with a diff and 300 whp and tq. it was faster, but the rx8 is still more fun to drive/control..

hey, but what do i know..

beers :beer:

wankinit 01-08-2018 06:50 AM

Sub’d (For laughter)

AAaF 01-08-2018 06:55 AM

Brett/Team, I was hoping we could be a bit more educative, it started off very well!

1:
To start with, I'd like to be educated regarding the x.xx housings you are vigorously discussing. I think I got how to estimate compressor requirements, but I do not understand this discussion. Could it be possible to explain with some numbers/pictures please? That would be much appreciated!

2:
To stick my neck out regarding compressor map interpretation:
I made a Excel sheet where I estimate requirements for my 6 port. Ve is just visually found in below picture from the curve with S-DAIS(6-port):
https://cimg5.ibsrv.net/gimg/www.rx8...56813108a0.png

If these calculations are remotely correct, it seems to me like 7061 compressor is not suited(pressure is absolute, so 2bar is what we normally would call 1 bar or 14.7PSI charge pressure). And by the same logic, 7670 is equally unsuited, since it only have higher capacity at higher pressure, as Team mention:

https://cimg9.ibsrv.net/gimg/www.rx8...874e4a7f0c.png

It could be that I have overlooked something in my numbers, like decreasing Ve when pressure is above atmosphere(..?), but if I put in the numbers for Ve in the same stupid way for 13B-SI in the same table, this changes the picture drastically, and makes 7163 a good match:

https://cimg3.ibsrv.net/gimg/www.rx8...c1c62c04ef.png

Since Team have 4 port, it will be slightly better than for the estimated 6 port, since 4 port have a bit lower Ve, but only marginally.

Not trying to remotely give an impression that I have any expertise(and zero experience!), but as mentioned earlier at this forum, I like to understand thing to a basic level, therefore I would really appreciate someone explaining me what's wrong. Mistakes is what you learn from:)

This also makes me think that reduced Ve as RPM increase is actually a benefit when turbocharging, if you want a broad power band. And this again makes me thing that Renesis is really not playing along with a turbo, not only do we cover a broader RPM range, rising Ve is also making it more difficult to find a suited compressor.

Bugger. Please prove me wrong:cussing:

TeamRX8 01-08-2018 08:16 AM

First, you’re only looking at peak choke values on the compressor map. As I stated, this is not intended as a track car. As a street car it may possibly see those peak numbers for the occasional run out to redline, but otherwise it would normally be operating at much lower values in the more efficent flow map area

Second, the fuel of choice for this is E85. It allows much higher boost levels than premium gasoline, even if those higher boost levels are programmed in to only be used at low - mid rpm levels and then possibly tapering down from mid-redline rpm range. In theory it should easily support mid-20 psig boost, but initially I figure to limit boost to 20 psig. EDIT: That's also NA VE, which is not the same as turbo VE

The engine will be built for this and in general, if all the other parameters are setup properly, the only thing that’s in question is how long the Renesis side seals will last due to the expansion and exposure in the exhaust port area. I do want to stress that this is a known issue for FI Renesis in general, and the plan is to do everything possible to address it and several other key points in the build process. If this happens, ithe engine won’t be some cobbled together garage build reusing old parts. This will be a full pro engine builder job with all the internal features and components required for the application duty.

Otherwise in general, your overall assessment is correct. The preferred turbo for the job, especially a 6-port engine, would be the BW EFR 8374. However, for low mount in an RX8 I doubt you could ever get that to fit in the low-mount position regardless of how much subframe and chassis structure customizing you do down there. In an RX8 chassis it pretty much has to be forward/top mount only. The best RX8 example I know of this would be Firecran’s car with an REW 13B engine. He sold it early last year. I wasn’t around on the forum much at that time and when I finally saw it was for sale and contacted him somebody in AZ had already beat me to the punch by several weeks.

So again, for this particular idea I only want to use a BW EFR turbo and only in the low mount position for a specific purpose; low-mid rpm power and torque on a street car. The EFR 7163 is the turbo that meets these requirements and for that purpose is the best fit. Now you might get the EFR 7670 to fit with reworking the structure to provide more space, but as was already discussed it becomes a moot point unless you intend to run 3 bar boost or higher because the EFR 7163 can otherwise provide the same flow coverage within 2 - 4 percent less efficiency at the choke line.

The forum used to fawn vigorously over the idea of fitting a Garrett GTX3076 back in the day. Now everybody thinks it’s too small. Well yeah, it always was too small and not a good choice in general, but it could fit in the low-mount position. Kind of amusing in general now.

Also, I don’t care to see any more childish commentary regarding me and anyone else and it won’t be tolerated. They can do their thing in their thread and I’m going to do my thing here. Please can that BS asap or I’ll be asking a Moderator to come assist you with it if you can’t handle it on your own. To address a particular point though, I don’t agree with Brettus on a number of technical issues, but otherwise have only respect and admiration for his efforts as well as forum contributions. My reply to his “it’ll never do that” comment several posts earlier shouldn’t be taken to mean anything other than we disagree on that assessment.

This concept is intended to only prove out my own ideas and objectives for a Renesis FI application. This thread doesn’t involve him otherwise. So if you feel like he needs your attention then please take it over to his thread.



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0-TO-100_Real_Quick 01-08-2018 09:35 AM


Originally Posted by TeamRX8 (Post 4848323)
Second, the fuel of choice for this is E85. It allows much higher boost levels than premium gasoline, even if those higher boost levels are programmed in to only be used at low - mid rpm levels and then possibly tapering down from mid-redline rpm range. In theory it should easily support mid-20 psig boost, but initially I figure to limit boost to 20 psig.

The engine will be built for this and in general, if all the other parameters are setup properly, the only thing that’s in question is how long the Renesis side seals will last due to the expansion and exposure in the exhaust port area. I do want to stress that this is a known issue for FI Renesis in general, and the plan is to do everything possible to address it and several other key points in the build process. If this happens, ithe engine won’t be some cobbled together garage build reusing old parts. This will be a full pro engine builder job with all the internal features and components required for the application duty.
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Do you have a rough idea of what engine modifications you'll want to accommodate these levels of pressure, or will you leave that up to your engine builder to recommend? Since most people swap Renesis internals for RX7 internals, like springs and seals, how "stock" are you going to try and keep this Renesis? I'm honestly very curious as to what your build will yield, and I hope you'll include more than just the turbo design configuration/information. Good luck man.

TeamRX8 01-08-2018 10:56 AM

Assuming it happens, the engine will have new rotor housings and new rotors/corner seals/etc. that are EDM cut for the deeper 2mm RX7 apex seals. I had intended to use Iannetti “Gold” seals and springs, which are their premium turbo application offering, but there’s a new steel seal coming that if it’s everything certain Pro builders are claiming (meaning they are) is pretty much going to blow everything else out of the water wrt quality at an extremely reasonable price. Not sure if I’m at liberty to talk about it publicly yet though, so that’s all I can say for now except they’re rated for 20 psig boost snd E85 compatible. Also, over the years builders have shared their secrets with me on a number of things and I show my respect by not throwing them under the bus by blabbing about it on forums. So sorry, I won’t/can’t tell you everything in full detail.

Brettus 01-08-2018 12:52 PM


Originally Posted by TeamRX8 (Post 4848323)
My reply to his “it’”ll never work” comment several post earlier shouldn’t be taken to mean anything other than that.


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What I actually said was "it is a good choice" and "it wont make 360" .
I actually think it will work fairly well , just below your expectations and not even remotely close to what the same turbo would do in an REW.

TeamRX8 01-08-2018 02:36 PM

Well it equated that in my mind, but just the same; my apology for not representing your comment properly, which I'll go back and adjust it to state that instead.

Otherwise I and others disagree. Maybe we'll find out sooner or later ...

AAaF 01-08-2018 11:37 PM

20psig definitively changes the picture to the better. But still, it looks like the different Ve makes significant difference with the same turbo on the two engines. For a 13B-SI it looks perfect, but from below picture, I would guess that we should not expect the same HP from Renesis as on the 13B-SI? Did a slightly better job than last time:
https://cimg0.ibsrv.net/gimg/www.rx8...dafac6c8e9.png

But the low and midrange looks to be quite equal, and thats the goal.

One thing, when I was guesstimating on the different numbers, I was really out of my depth, does these look remotely correct? If not, which and what should they be changed to?

https://cimg0.ibsrv.net/gimg/www.rx8...f6bb16b71a.png

TeamRX8 01-09-2018 12:55 AM

what's going to be harder to plot on MatchBot is the lighter and tighter turbine on the EFR 7163 13B-MSP side-exhaust port engine as compared to the EFR 7670 13B peri-exhaust port engine.

I'm expecting that to offset at least some of the exhaust pulse energy difference, but then until it's actually done that's just an opinion based on theoretical logic rather than actual results. SOme people disagre with that premise. I think they're discounting it too easily.

Also,the 350 rwhp estimate for this concept is based on 47 lb/min @ 7500 rpm redline on the compressor map and you have it plotted out to 60 lb/min @ 8000. I have zero intention to run that much power or rpm level with this turbo build concept.

If you go look at Punchy Lightbeers ( :lol: that name still cracks me up) boobtube video he's at almost 290 rwhp @ 11 psig with the not so well thought out EFR 7163 on a 6-port Renesis.. In the 7670 dyno run thread link I posted earlier, Howard Coleman cranked out some rwhp estimate @ certain boost levels for the 7670 turbo. Which his number for 10 psig is pretty much on target with Punchy's result. That's no guarantee that it will still match at higher boost pressures, but it's one of several indicators which has been overlooked by some people. You can 't just look at the results and go blah-blah-blah. Well I suppose you can do that, which is most of disagreement issue imo. You have to look at what they may be doing right or wrong in the overall sense to make a proper assessment.



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Brettus 01-09-2018 01:53 AM


Originally Posted by TeamRX8 (Post 4848406)

That's no guarantee that it will still match at higher boost pressures,.

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Bingo ! The one parameter you don't know and will never know unless you actually go there ........... Is BSFC.

TeamRX8 01-09-2018 02:00 AM

I probably know those figures better than you do. I didn't have to go there because other people did and shared their detailed info with me. Again, I disagree with your position.

Brettus 01-09-2018 02:31 AM


Originally Posted by TeamRX8 (Post 4848408)
I probably know those figures better than you do. I didn't have to go there because other people did and shared their detailed info with me. Again, I disagree with your position.

would you mind sharing ? I've been using 0.6 which seems to line up pretty well with my setup ............. up to the point that it doesn't .

TeamRX8 01-09-2018 03:42 AM

it's not necessarily the engine, otherwise I have nothing else to say.

acroy 01-09-2018 09:03 AM

^^ I really like the idea. Good luck! keep us updated.

Brettus 01-09-2018 11:54 AM


Originally Posted by TeamRX8 (Post 4848412)
it's not necessarily the engine, otherwise I have nothing else to say.

This is where you are (largely) mistaken ...

NotAPreppie 01-09-2018 12:00 PM

I feel like Brettus is goading Team just to see if Team will actually do it.

Brettus 01-09-2018 12:22 PM

Well ....if he doesn't do it ...this thread is nothing but fluff !

TeamRX8 01-09-2018 04:56 PM


Originally Posted by Brettus (Post 4848484)
This is where you are (largely) mistaken ...


You’d be better served to focus on figuring out your own mistakes that are being overlooked.

Otherwise anything Brettus has say doesn’t have any influence on my decision to spend the necessary finances or not to do this. I really don’t understand how people come to such ridiculous conclusions. :squint:


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TeamRX8 01-09-2018 05:12 PM


Originally Posted by Brettus (Post 4848494)
Well ....if he doesn't do it ...this thread is nothing but fluff !

Look, I’ve made it clear that there’s no rivalry between us and I’ve also done everything I can to put a stop on that. I’ve also gone out of my way to speak favorably about you with as much respect as possible. Otherwise you seem to have treated me rather unfairly in your thread and then a hate filled vulture or two swooped in to sh-t bomb me knowing full well I couldn’t respond without breaking my word that it was my last post there.

Now I’m not a grudge person and could really care less about being petty because in the end none of that bs really matters in life. However, I’m not going there again with you. As far as I’m concerned you can go back to your own thread and park your “I’m the turbo Renesis God” ego there. I’ll still continue to pray for God to enlighten you and save your soul, but otherwise likely won’t be responding back directly to anything you ask or say here. It’s not personal, I just don’t care any more as far as your RX8 ideas and opinions are concerned. That’s all I have to say about it. Again, best wishes at reaching your target goal with your own turbo project. I do look forward to seeing the end result.


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NotAPreppie 01-09-2018 08:42 PM

If you're so unconcerned by his opinion, why not just ignore him?

TeamRX8 01-09-2018 09:24 PM

What part about “from now on” implied in the last reply don’t you understand? I also don’t appreciate you bringing your personal beef with me here trying to egg him on and getting involved between me and him when it’s none of your business.

The earlier reply about getting a moderator involved if you can’t handle it yourself applies as much to you as anyone else. If you’re only interest is engaging in petty bs that doesn’t involve you rather the topic then I don’t have any issue dusting the dirt from your town off my shoes to also ignore you or anyone else who wants to sail that tack either.





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RIWWP 01-09-2018 10:14 PM

I very much want to see where the technical discussion goes. Something outside the box is refreshing, and with the amount of experience here something could actually be made of it.

TeamRX8 01-10-2018 12:24 AM

thanks RIWWP, and good to see you back on the forum recently!

I'm more open to the idea that it might fall flat on it's face or come up way short as Brettus suggested more than it may come across by my replies, but I've shared the idea with people who imo have the experience to trump any one of us on this forum and they think the idea is thought out and sound in general. There is a chance that eliminating the UIM might have more impact than I think, but honestly what it takes to put it back; move the discharge outlet to the other side on the IC discharge header, install UIM & T-Body, pipe between those two points, is easy enough to just go ahead and try it without first.

TeamRX8 01-10-2018 12:49 AM


Originally Posted by AAaF (Post 4848405)
it looks like the different Ve makes significant difference with the same turbo on the two engines.

I'm not sure how you're deriving Ve values?. I did see where you were referring to some Mazda Ve values in an earlier post. Which I edited my reply to that post after going back and catching it.

That graph is indicating NA Ve values on unmodified ports as supplied by Mazda. Once you port and/or use a turbo they can be vastly different from the Mazda graph and not necessarily in a linear or easily estimated way either.

TeamRX8 01-10-2018 01:54 AM

1 Attachment(s)
I also want to include the attached pdf document, which shows some of the early issues Pettit Racing experienced on the Garrett GT35 turbo’d Renesis they supplied for the Diasio 962RT race car company. They were finally able to sucessfully run 3:1 PR and higher after making the necessary improvements to allow doing so ...

Note that this is counter to some of the opinions and comments by some of the nay-sayers.


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