What do you think of this manifold?
 

I pulled this off my 94' from Puerto Rico.
What do you think of the layout?

https://www.rx7club.com/forum/attach...postid=2155944

I am not crazy about the dump of the Wastegate into the open.

The wastegate runner is going the wrong direction, you can always plumb the WG back into the DP farther down. It is undivided(not optimum) and the runners are shorter than optimal, all in all about what many run, but far from optimum.

Thanks. Anyone else have comments?

That looks like a SFP manifold!

What is "SFP"?

South Florida Performance.

Typical... but far from optimal as Carl said.

-Chris

Is the exhuast side diveded on the turbo?,if not, that may be why it's not a divided manifold though it could still benifit from it to some degree, I don't see how the wastgate runner is going in the wrong direction though, you would need to see in the manifold to see how it mates up with the runners, ie. if it is angled slightly downward it wouldn't be bad, you could also cut the wastegate flange off turn it clockwise 90' and you would be good to go for rerouting it back in the DP.

What about this one on EBAY?
 

Funny, a few years ago I ragged on the A-Spec Tuning FD kit and it had a worse design that the SFP unit, and I got jumped on for bagging on their stuff.&nbsp Now, it looks like consumers are getting a lot more knowledgable about turbo exhaust manifold design. :)

The SFP one is not that bad, IMO.&nbsp We're going to try and run a similar design for a Zenki 13BT soon with a Garrett GT-35xx.&nbsp The reason for running the wastegate discharge from the base of the turbine inlet flange is due to a high pressure area for the exhaust gases right before going into the turbine - see Corky Bell "Maximum Boost" for pics on this set-up.&nbsp Sure, it's not optimal in exhaust gas vector direction, but running an HKS GT wastegate should more than handle any exhaust exiting responsibilities. :) The one bad design flaw of the SFP unit is the fact it's using unbalanced runners to the turbo.

That other eBay SS shiny unit I don't like at all.&nbsp Unbalanced runners with non-optimum placement of wastegate discharge makes for an inefficient design.

True, but you sometimes you don't come off right either, and I think most people on here only know just enough to think they know ehough wouldn't you agree.:)

-Sean

Sure, but when Corky Bell supports it in his book, I would think that's pretty good evidence that you're on the right track. :)

Most of this turbo exhaust manifold design stuff is common sense - think like a gas molecule.&nbsp Corky Bell does a good job in "Maximum Boost" to go into depth on what is good and what is bad in terms of turbo exhaust manifolds...


-Ted

I would agree,and that's why when I got the time to redesign the manifold I did, keep in mind the first time I asked someone else to handle it for me and that mistake wont happen again,but I do get so tired of hearing "Corkey Bell says" don't you?

The SFP might look un-balance from the outside but from the inside both sides are very closely collected.

Your right. I took a line and measured the runners on my manifold (from the pic above). They are pretty damn close in length. Visually, it is deceiving.

I dunno...
Not many times I've heard people say they get tired of the Bible or the dictionary...


-Ted

Corky bell , I might add , has had plenty of fuckups of his own, and is not the be all and end all of trubo installation, while I do like his book, and some of the theory in it, its not possible sometimes to incorporate all of it perfectly into a design.. When he shows a "bad" or "poor" installation, he does not show the same car with his alternative installed, its ok to posture from the sidelines, its a whole different story to be the one holding the tig torch...
Ask corky about turbocharging NSX's...He just about lost is ass over that kit, maybe he forgot to read his own book...Max

Sure, I understand where you're coming from, but his manifold design section is pretty damn good.&nbsp I don't see anyone offering alternatives out there?&nbsp You can criticize Corky Bell and his book all you want, but I haven't come across anything better that's in print...

I don't see anything wrong with what he talks about when building a turbo exhaust manifold.&nbsp Might I ask where you have a beef with Corky Bell on this particular subject?


-Ted

i don't think that is a sfp manifold, of all the ones i have seen none have the waste gate dump there......mine also says sfp and so do all my friends that have the sfp manifold...

A lot of the early ones did not have the SFP badge on it and also had the pipe for the wastegate in that position.

Find a good technical library in a trade school, there are more books out there than Corky's , I have a whole range of books written on the subject of manifold building and tuning, Hugh Macinnes, smokey Yunik, Mickey Thompson, Dave Vizard, have all touched on the subject of manifold design, especially tuned length runners for both n/a and forced induction, they actually give you the calculations, and the workable physics behind it, not just,"it works better" or " we saw a measurable difference", gee thanks corky, I feel so enlightened...
His theory though sound, oops or his assumption, shows up in his book, but doesn't seem to follow what he sells in real life, I bought his book, and was actually a little dissapointed in the fact that it was more shear opinion on most of the subjects, while he fails to show the theory in depth behind it, and thats what makes Hugh Macinnes's book especially so much better, even though its quite dated, its far better book for actual turbo application.. Bell is the Martha Stewart of the turbo world, he just regurgitates what everyone already knows, but was just selling no more than common sense in the book.. Can you size a turbo from Maximum boost, not really, from Hugh Maciness, yeah probably...
Corky bell needs to write a postscript in Maximum boost, that reads. "all the project cars used for examples in this book were finished by someone else that actually knew what they were doing, or sold and parted out because they never worked right, I think that Jag is still for sale, it was in Hemmings for years...
There are lots of people out there in this world like Corky that talk a good game, but can't play it in real life, most of them crown themselves as experts and then write books unfortunatly...Max

I have an early one that looks exactly like that. A friend of mine got a later one and the wastegate pipe was on the outside(does not work on a right hand drive car) and had to be changed. The pic is very misleading. As far as runner length goes they are very close to the same. I swear by this manifold, very stout.

I have the Hugh MacInnes book, and it's really outdated.&nbsp I haven't seen any of the other authors' writings, but I have a feeling they are all NA applications mostly?&nbsp If so, it's almost not applicable.&nbsp I do not recognize David Vizard's name though - I did a quick search on his name on Amazon, and it looked mostly like NA applications.

Have you seen the SAE papers on the (turbo) rotary engine?&nbsp I'll take this reference over any published media list, including Corky Bell's.

I think Corky Bell's "Maximum Boost" is a bit too simplified for your mind.&nbsp I think it's a great book for the beginner, and I think it was written at that level.&nbsp Hell, even the Hugh MacInnes "Turbocharging" was written at a much higher level.&nbsp I'd like to hear any options for the newbie who'd like to read up on turbocharging?




I agree the publication was too biased towards his company, BEGI.


I learned how to size turbos from "Turbocharging", although it uses the old standards of airflow for computations.&nbsp Other than that, the only other thing that was interesting was the water injection chart.


See above - I agree that it's titled towards his products; I never bought the book to read up on his VNT crap.&nbsp I did buy it because it was a publication on modern turbocharging theory.&nbsp There are very few publications available in the local bookstore on such subjects.&nbsp I had no problem following Corky Bell's explanation on turbo sizing...


I think it's a waste of time trying to argue the merits of Corky Bell's "Maximum Boost".&nbsp I still find it interesting, although the $30+ cost is rather high.&nbsp I still recommend this a read for most people trying to read up on turbocharging.&nbsp Very few of them can access special trade publications and materials that are limited.&nbsp I'm still looking for alternatives to "Maximum Boost", but I haven't found any suitable suggestions...I don't think applications on NA header an and exhuast tuning is especially useful in this case.
If nothing exiciting comes out of this thread, my additions end here.


-Ted

Ted, you mentioned some SAE papers on turboed rotaries. Do you have their numbers? Thanks.

The only difference between a boosted engine and non boosted engine is the charge density, by all means n/a tuning applies, if it were not so, would the equal length turbo header not be so important? Remember the advantages of equal length were first found on n/a engines, and that tuning the exhaust pulses had merit.
I have a series of books called Super power, that are better than bells book for introduction to forced induction, as a plus they cover supercharging, intake design, efi theory, and nitrous application, its an older set, but you still see them around, far better read than Maximum boost..
I think what sets Macinnes apart from bell is the definite anwers, when you read macinnes, he starts sentences with "here is", "this is how"," THis is why", where as bell writes "Generally" "sometimes","it maybe"..etc etc...
When I put my system together, I can truthfully say, when I was stuck or unsure of something, I picked up maximum boost, but more often than not, I found for definitive answer, I ended up looking and finding it in"turbochargers", being that I have been through the turbocharger from scratch mill, I can say that for those interested in doing their own system , turbochargers is far better book...Max

regardless of the debate over how good 'Maximum Boost' is for the advanced in here, it's been an interesting read sofar for me and i consider myself a beginner with my FC TII being my first turbocharged car ever owned

reted, I had a thread in the 2nd gen forum that was moved before anyone saw it to the lounge, but what i was hoping to find out was if there was an easy way to convert some of bell's formulas he's using to calculate engine cfm for a piston to a 13bt? i'm typically very bad at mathamatics so my head already spins when reading half of this book, but i'd like to get it right because i'm hoping to do a t04 upgrade this winter on my TII and i want to figure out what power curves i'd see from the different sizes out there.

<punt>

To make it easy, we usually use 30 lbs/min as a general rule of thumb for a 13B.&nbsp Pressure ratio just minus 1.00 and multiply by ~14 to get psi equivalent.&nbsp It's easy to stare at the compressor maps using this shortcut...


-Ted

The common cfm formulas are intended for 4-stroke piston engines which only fire half of their displacement for each revolution of the output shaft. A rotary engine, much like a 2-stroke piston engine, fires all of its rated displacement for each revolution of the output shaft. Therefore, just remove this function from the formula, which will either be a 2 in the denominator, or a 0.5 in the numerator.

The Supercharged book is better than the Maximum Boost book, and shows compressor charts in the more modern lbs/min format as opposed to the older cfm format. Corky Bell has a lot of experience with rotary engines, but for some reason he has left them out of his books. Shame on him! :spank:

Other Corky Bell corrections or explanations that I can think of off the top of my head:

1 bar = 14.5 PSI, not 14.7 PSI. This is not to be confused with his Pressure Ratio formula of PR = (14.7+boost)/14.7, which is correct.

Rotary engines tend to prefer very thick, solid header flanges as opposed to those individual runner flanges shown in the book.

His comments on water injection are from a road racing and street car standpoint.

If you can get his intercooler sizing formula to work in real life, please let me know. Otherwise, I'm sticking to the Spearco charts. :)

Check out...

http://www.thecarricos.com/ACRE/

The "New-tech..." and "Recent-tech..." .PDF files should be SAE papers someone converted.

If not, the titles are:
S. Tashima et al, "Sequential Twin Turbocharged Rotary Engine
of the Latest RX-7", SAE paper 941030

Takumi Muroki
Recent Technology Development of High-Powered Rotary Engine at Mazda
SAE paper 841017
(This one is one of the .pdf files mentioned above.)



-Ted

Ted, you mention 30lbs/min for a rotary...standard port? What would I be looking at ballpark for Cosmo ports, very large secondaries and moderate primaries? Trying to decide which GT40 compressor and turbine would be best for a very nice street setup. Seems like the GT40 82mm, 50 trim, .58 a/r would be better around 1.1kg (16psi "ish") than the 88mm 54 trim, .72a/r. The 88mm looks as if you could "grow" into it for racing purposes and it seems to flow very well at lower boost levels in it's highest efficiency range. Which turbine would match up well, the 84 trim 1.19a/r divided? The 73 trim looks too small at 30lbs/min? Am I reading this right?
http://www.turbobygarrett.com/turbob...%2017%2013.pdf

Must add, what I have now, GReddy T78, uses what I believe to be a GT40 compressor wheel with the stock T78 exhaust housing/turbine. I'm sure the Garrett GT turbine/housing is a bit more modern and efficient. I'm not sure, given my current setup, that the GT40 compressor wheel and the Mitsu turbine are a perfect match.

30 lbs/min as a rule, but if we're talking ported motor, I look at the 30lbs/min to 40 lbs/min "range".


It's dependent on how your turbo exhaust manifold is built.&nbsp For a totally divided turbo exhaust manifold (the GT40's all some with divided turbine housings), the 0.94 A/R turbine would make for super quick spool-up.&nbsp With a collected manifold, it should still be quick spooling, but tame on boost onset.&nbsp The 1.19 A/R turbine would make for a nice powerband all the way to redline (i.e. 7kRPM) with a collected turbo exhaust manifold - too bad you can't gank the 1.34 A/R turbine from the 54 trim and stuff that on a divided turbo exhaust manifold! :D

I would recommend going with the 54 trim comp and the 84 trim turbine with the 1.34 A/R turbine housing and stuff everything on a divided turbo exhaust manifold.&nbsp Boost should easily come up in the 3,500RPM range and pull all the way to redline.&nbsp Even at low boost levels like 7psi (~1.5 pressure ratios), the efficiency plateau is still in the mid 70% - the top plateau is 78% max, so it's not a big drop.&nbsp The turbo should work very well with a nice, ported 13BT, Cosmo 13B-RE or FD 13B-REW...


-Ted

Excellent! Thanks for the info! I currently have a non-divided GReddy T78/88 manifold (first design, the present day designs are fully divided) and thus I'm not completely happy w/boost response on my current setup. The primary runners are also larger than on the newest design

You lost me on the last sentence, first paragraph "The 1.19 A/R turbine would make for a nice powerband all the way to redline (i.e. 7kRPM) with a collected turbo exhaust manifold - too bad you can't gank the 1.34 A/R turbine from the 54 trim and stuff that on a divided turbo exhaust manifold!"

Why can't you run the 1.34 turbine housing on a divided manifold with a 54 trim? Isn't that what you're saying to do in the first sentence, last paragraph? Am I just confused? :-)

Yeah, you got it - I wrote that late at night, and I think I confused myself. :)

Good luck!



-Ted

Do you think the 1.19 A/R turbine would be a good compromise between spool and power?

My thoughts on GT40R sizing;
The more research I do the more I think I'd like to put a T66 in my car.(The car is a fully built 13brew rotary road race car with a goal of 550rwhp) At the same time I'd like to take advantage of the relatively low cost, and great performance of the Garrett GTBB series Turbos. With this in mind I've been comparing the specs on various GT turbos to the Turbonetics Q trim T66. I am basing this on a 1.00 ar T66 since I know of a couple of guys who are using it on a T66 with good results. A GT40 comes the closest, although the compressor turbine pairing in the Garrett catalog seems to use a larger turbine than the T66 with a comparable compressor.
Turbonetics T66 specs(assuming I am reading their catalog correctly)
compressor;
90mm wheel,2.58minor,3.584 major=52 trim
turbine;
78mm, 2.693 minor, 3.111 major=75 trim, 1.00ar

Garrett GT40 Ball bearing standard specs;

(1.) 82mm 50 trim compressor, 77mm 73 trim .94 ar turbine
or
(2.) 88mm 54 trim compressor 77mm 84 trim 1.34ar turbine
QUESTIONS;
How will the first Garrett option(your initial suggestion) spool compared to the T66, and how will the ultimate HP compare? or should I(can I) try to get the larger Garrett compressor with the smaller Garrett turbine (almost the same as a T66 Qtrim) ie
T66-- 90mm 52 trim compressor, 78mm 75 trim 1.00ar turbine
GT40-88mm 54 trim compressor, 77mm 73 trim .94ar turbine
Do you know if the dispacement recomendations in the Garrett catalog are based more heavily on compressor or turbine sizing?
Garrett lists the suggested displacement for a GT35 @ 2.5L-3.2L, and a GT40 @ 3.5L-5.0L, and since a GT35/40 uses a GT40 compressor(?), I am guessing the displacement recommendation relates more to turbine size(yes?)
I'm convinced the 35/40 is a bit small for 550rwhp. Carl

Hey Ted. You don't know how pleased I was to find all that information. Thanks.